1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2
3 /*
4 * Common eBPF ELF object loading operations.
5 *
6 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
7 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
8 * Copyright (C) 2015 Huawei Inc.
9 * Copyright (C) 2017 Nicira, Inc.
10 * Copyright (C) 2019 Isovalent, Inc.
11 */
12
13 #ifndef _GNU_SOURCE
14 #define _GNU_SOURCE
15 #endif
16 #include <stdlib.h>
17 #include <stdio.h>
18 #include <stdarg.h>
19 #include <libgen.h>
20 #include <inttypes.h>
21 #include <limits.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <endian.h>
25 #include <fcntl.h>
26 #include <errno.h>
27 #include <ctype.h>
28 #include <asm/unistd.h>
29 #include <linux/err.h>
30 #include <linux/kernel.h>
31 #include <linux/bpf.h>
32 #include <linux/btf.h>
33 #include <linux/filter.h>
34 #include <linux/list.h>
35 #include <linux/limits.h>
36 #include <linux/perf_event.h>
37 #include <linux/ring_buffer.h>
38 #include <linux/version.h>
39 #include <sys/epoll.h>
40 #include <sys/ioctl.h>
41 #include <sys/mman.h>
42 #include <sys/stat.h>
43 #include <sys/types.h>
44 #include <sys/vfs.h>
45 #include <sys/utsname.h>
46 #include <sys/resource.h>
47 #include <libelf.h>
48 #include <gelf.h>
49 #include <zlib.h>
50
51 #include "libbpf.h"
52 #include "bpf.h"
53 #include "btf.h"
54 #include "str_error.h"
55 #include "libbpf_internal.h"
56 #include "hashmap.h"
57
58 #ifndef BPF_FS_MAGIC
59 #define BPF_FS_MAGIC 0xcafe4a11
60 #endif
61
62 #define BPF_INSN_SZ (sizeof(struct bpf_insn))
63
64 /* vsprintf() in __base_pr() uses nonliteral format string. It may break
65 * compilation if user enables corresponding warning. Disable it explicitly.
66 */
67 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
68
69 #define __printf(a, b) __attribute__((format(printf, a, b)))
70
71 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj);
72 static bool prog_is_subprog(const struct bpf_object *obj, const struct bpf_program *prog);
73
__base_pr(enum libbpf_print_level level,const char * format,va_list args)74 static int __base_pr(enum libbpf_print_level level, const char *format,
75 va_list args)
76 {
77 if (level == LIBBPF_DEBUG)
78 return 0;
79
80 return vfprintf(stderr, format, args);
81 }
82
83 static libbpf_print_fn_t __libbpf_pr = __base_pr;
84
libbpf_set_print(libbpf_print_fn_t fn)85 libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
86 {
87 libbpf_print_fn_t old_print_fn = __libbpf_pr;
88
89 __libbpf_pr = fn;
90 return old_print_fn;
91 }
92
93 __printf(2, 3)
libbpf_print(enum libbpf_print_level level,const char * format,...)94 void libbpf_print(enum libbpf_print_level level, const char *format, ...)
95 {
96 va_list args;
97
98 if (!__libbpf_pr)
99 return;
100
101 va_start(args, format);
102 __libbpf_pr(level, format, args);
103 va_end(args);
104 }
105
pr_perm_msg(int err)106 static void pr_perm_msg(int err)
107 {
108 struct rlimit limit;
109 char buf[100];
110
111 if (err != -EPERM || geteuid() != 0)
112 return;
113
114 err = getrlimit(RLIMIT_MEMLOCK, &limit);
115 if (err)
116 return;
117
118 if (limit.rlim_cur == RLIM_INFINITY)
119 return;
120
121 if (limit.rlim_cur < 1024)
122 snprintf(buf, sizeof(buf), "%zu bytes", (size_t)limit.rlim_cur);
123 else if (limit.rlim_cur < 1024*1024)
124 snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024);
125 else
126 snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024));
127
128 pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n",
129 buf);
130 }
131
132 #define STRERR_BUFSIZE 128
133
134 /* Copied from tools/perf/util/util.h */
135 #ifndef zfree
136 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
137 #endif
138
139 #ifndef zclose
140 # define zclose(fd) ({ \
141 int ___err = 0; \
142 if ((fd) >= 0) \
143 ___err = close((fd)); \
144 fd = -1; \
145 ___err; })
146 #endif
147
ptr_to_u64(const void * ptr)148 static inline __u64 ptr_to_u64(const void *ptr)
149 {
150 return (__u64) (unsigned long) ptr;
151 }
152
153 enum kern_feature_id {
154 /* v4.14: kernel support for program & map names. */
155 FEAT_PROG_NAME,
156 /* v5.2: kernel support for global data sections. */
157 FEAT_GLOBAL_DATA,
158 /* BTF support */
159 FEAT_BTF,
160 /* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
161 FEAT_BTF_FUNC,
162 /* BTF_KIND_VAR and BTF_KIND_DATASEC support */
163 FEAT_BTF_DATASEC,
164 /* BTF_FUNC_GLOBAL is supported */
165 FEAT_BTF_GLOBAL_FUNC,
166 /* BPF_F_MMAPABLE is supported for arrays */
167 FEAT_ARRAY_MMAP,
168 /* kernel support for expected_attach_type in BPF_PROG_LOAD */
169 FEAT_EXP_ATTACH_TYPE,
170 /* bpf_probe_read_{kernel,user}[_str] helpers */
171 FEAT_PROBE_READ_KERN,
172 /* BPF_PROG_BIND_MAP is supported */
173 FEAT_PROG_BIND_MAP,
174 /* Kernel support for module BTFs */
175 FEAT_MODULE_BTF,
176 /* BTF_KIND_FLOAT support */
177 FEAT_BTF_FLOAT,
178 __FEAT_CNT,
179 };
180
181 static bool kernel_supports(enum kern_feature_id feat_id);
182
183 enum reloc_type {
184 RELO_LD64,
185 RELO_CALL,
186 RELO_DATA,
187 RELO_EXTERN_VAR,
188 RELO_EXTERN_FUNC,
189 RELO_SUBPROG_ADDR,
190 };
191
192 struct reloc_desc {
193 enum reloc_type type;
194 int insn_idx;
195 int map_idx;
196 int sym_off;
197 };
198
199 struct bpf_sec_def;
200
201 typedef struct bpf_link *(*attach_fn_t)(const struct bpf_sec_def *sec,
202 struct bpf_program *prog);
203
204 struct bpf_sec_def {
205 const char *sec;
206 size_t len;
207 enum bpf_prog_type prog_type;
208 enum bpf_attach_type expected_attach_type;
209 bool is_exp_attach_type_optional;
210 bool is_attachable;
211 bool is_attach_btf;
212 bool is_sleepable;
213 attach_fn_t attach_fn;
214 };
215
216 /*
217 * bpf_prog should be a better name but it has been used in
218 * linux/filter.h.
219 */
220 struct bpf_program {
221 const struct bpf_sec_def *sec_def;
222 char *sec_name;
223 size_t sec_idx;
224 /* this program's instruction offset (in number of instructions)
225 * within its containing ELF section
226 */
227 size_t sec_insn_off;
228 /* number of original instructions in ELF section belonging to this
229 * program, not taking into account subprogram instructions possible
230 * appended later during relocation
231 */
232 size_t sec_insn_cnt;
233 /* Offset (in number of instructions) of the start of instruction
234 * belonging to this BPF program within its containing main BPF
235 * program. For the entry-point (main) BPF program, this is always
236 * zero. For a sub-program, this gets reset before each of main BPF
237 * programs are processed and relocated and is used to determined
238 * whether sub-program was already appended to the main program, and
239 * if yes, at which instruction offset.
240 */
241 size_t sub_insn_off;
242
243 char *name;
244 /* sec_name with / replaced by _; makes recursive pinning
245 * in bpf_object__pin_programs easier
246 */
247 char *pin_name;
248
249 /* instructions that belong to BPF program; insns[0] is located at
250 * sec_insn_off instruction within its ELF section in ELF file, so
251 * when mapping ELF file instruction index to the local instruction,
252 * one needs to subtract sec_insn_off; and vice versa.
253 */
254 struct bpf_insn *insns;
255 /* actual number of instruction in this BPF program's image; for
256 * entry-point BPF programs this includes the size of main program
257 * itself plus all the used sub-programs, appended at the end
258 */
259 size_t insns_cnt;
260
261 struct reloc_desc *reloc_desc;
262 int nr_reloc;
263 int log_level;
264
265 struct {
266 int nr;
267 int *fds;
268 } instances;
269 bpf_program_prep_t preprocessor;
270
271 struct bpf_object *obj;
272 void *priv;
273 bpf_program_clear_priv_t clear_priv;
274
275 bool load;
276 bool mark_btf_static;
277 enum bpf_prog_type type;
278 enum bpf_attach_type expected_attach_type;
279 int prog_ifindex;
280 __u32 attach_btf_obj_fd;
281 __u32 attach_btf_id;
282 __u32 attach_prog_fd;
283 void *func_info;
284 __u32 func_info_rec_size;
285 __u32 func_info_cnt;
286
287 void *line_info;
288 __u32 line_info_rec_size;
289 __u32 line_info_cnt;
290 __u32 prog_flags;
291 };
292
293 struct bpf_struct_ops {
294 const char *tname;
295 const struct btf_type *type;
296 struct bpf_program **progs;
297 __u32 *kern_func_off;
298 /* e.g. struct tcp_congestion_ops in bpf_prog's btf format */
299 void *data;
300 /* e.g. struct bpf_struct_ops_tcp_congestion_ops in
301 * btf_vmlinux's format.
302 * struct bpf_struct_ops_tcp_congestion_ops {
303 * [... some other kernel fields ...]
304 * struct tcp_congestion_ops data;
305 * }
306 * kern_vdata-size == sizeof(struct bpf_struct_ops_tcp_congestion_ops)
307 * bpf_map__init_kern_struct_ops() will populate the "kern_vdata"
308 * from "data".
309 */
310 void *kern_vdata;
311 __u32 type_id;
312 };
313
314 #define DATA_SEC ".data"
315 #define BSS_SEC ".bss"
316 #define RODATA_SEC ".rodata"
317 #define KCONFIG_SEC ".kconfig"
318 #define KSYMS_SEC ".ksyms"
319 #define STRUCT_OPS_SEC ".struct_ops"
320
321 enum libbpf_map_type {
322 LIBBPF_MAP_UNSPEC,
323 LIBBPF_MAP_DATA,
324 LIBBPF_MAP_BSS,
325 LIBBPF_MAP_RODATA,
326 LIBBPF_MAP_KCONFIG,
327 };
328
329 static const char * const libbpf_type_to_btf_name[] = {
330 [LIBBPF_MAP_DATA] = DATA_SEC,
331 [LIBBPF_MAP_BSS] = BSS_SEC,
332 [LIBBPF_MAP_RODATA] = RODATA_SEC,
333 [LIBBPF_MAP_KCONFIG] = KCONFIG_SEC,
334 };
335
336 struct bpf_map {
337 char *name;
338 int fd;
339 int sec_idx;
340 size_t sec_offset;
341 int map_ifindex;
342 int inner_map_fd;
343 struct bpf_map_def def;
344 __u32 numa_node;
345 __u32 btf_var_idx;
346 __u32 btf_key_type_id;
347 __u32 btf_value_type_id;
348 __u32 btf_vmlinux_value_type_id;
349 void *priv;
350 bpf_map_clear_priv_t clear_priv;
351 enum libbpf_map_type libbpf_type;
352 void *mmaped;
353 struct bpf_struct_ops *st_ops;
354 struct bpf_map *inner_map;
355 void **init_slots;
356 int init_slots_sz;
357 char *pin_path;
358 bool pinned;
359 bool reused;
360 };
361
362 enum extern_type {
363 EXT_UNKNOWN,
364 EXT_KCFG,
365 EXT_KSYM,
366 };
367
368 enum kcfg_type {
369 KCFG_UNKNOWN,
370 KCFG_CHAR,
371 KCFG_BOOL,
372 KCFG_INT,
373 KCFG_TRISTATE,
374 KCFG_CHAR_ARR,
375 };
376
377 struct extern_desc {
378 enum extern_type type;
379 int sym_idx;
380 int btf_id;
381 int sec_btf_id;
382 const char *name;
383 bool is_set;
384 bool is_weak;
385 union {
386 struct {
387 enum kcfg_type type;
388 int sz;
389 int align;
390 int data_off;
391 bool is_signed;
392 } kcfg;
393 struct {
394 unsigned long long addr;
395
396 /* target btf_id of the corresponding kernel var. */
397 int kernel_btf_obj_fd;
398 int kernel_btf_id;
399
400 /* local btf_id of the ksym extern's type. */
401 __u32 type_id;
402 } ksym;
403 };
404 };
405
406 static LIST_HEAD(bpf_objects_list);
407
408 struct module_btf {
409 struct btf *btf;
410 char *name;
411 __u32 id;
412 int fd;
413 };
414
415 struct bpf_object {
416 char name[BPF_OBJ_NAME_LEN];
417 char license[64];
418 __u32 kern_version;
419
420 struct bpf_program *programs;
421 size_t nr_programs;
422 struct bpf_map *maps;
423 size_t nr_maps;
424 size_t maps_cap;
425
426 char *kconfig;
427 struct extern_desc *externs;
428 int nr_extern;
429 int kconfig_map_idx;
430 int rodata_map_idx;
431
432 bool loaded;
433 bool has_subcalls;
434
435 /*
436 * Information when doing elf related work. Only valid if fd
437 * is valid.
438 */
439 struct {
440 int fd;
441 const void *obj_buf;
442 size_t obj_buf_sz;
443 Elf *elf;
444 GElf_Ehdr ehdr;
445 Elf_Data *symbols;
446 Elf_Data *data;
447 Elf_Data *rodata;
448 Elf_Data *bss;
449 Elf_Data *st_ops_data;
450 size_t shstrndx; /* section index for section name strings */
451 size_t strtabidx;
452 struct {
453 GElf_Shdr shdr;
454 Elf_Data *data;
455 } *reloc_sects;
456 int nr_reloc_sects;
457 int maps_shndx;
458 int btf_maps_shndx;
459 __u32 btf_maps_sec_btf_id;
460 int text_shndx;
461 int symbols_shndx;
462 int data_shndx;
463 int rodata_shndx;
464 int bss_shndx;
465 int st_ops_shndx;
466 } efile;
467 /*
468 * All loaded bpf_object is linked in a list, which is
469 * hidden to caller. bpf_objects__<func> handlers deal with
470 * all objects.
471 */
472 struct list_head list;
473
474 struct btf *btf;
475 struct btf_ext *btf_ext;
476
477 /* Parse and load BTF vmlinux if any of the programs in the object need
478 * it at load time.
479 */
480 struct btf *btf_vmlinux;
481 /* vmlinux BTF override for CO-RE relocations */
482 struct btf *btf_vmlinux_override;
483 /* Lazily initialized kernel module BTFs */
484 struct module_btf *btf_modules;
485 bool btf_modules_loaded;
486 size_t btf_module_cnt;
487 size_t btf_module_cap;
488
489 void *priv;
490 bpf_object_clear_priv_t clear_priv;
491
492 char path[];
493 };
494 #define obj_elf_valid(o) ((o)->efile.elf)
495
496 static const char *elf_sym_str(const struct bpf_object *obj, size_t off);
497 static const char *elf_sec_str(const struct bpf_object *obj, size_t off);
498 static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx);
499 static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name);
500 static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr);
501 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn);
502 static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn);
503
bpf_program__unload(struct bpf_program * prog)504 void bpf_program__unload(struct bpf_program *prog)
505 {
506 int i;
507
508 if (!prog)
509 return;
510
511 /*
512 * If the object is opened but the program was never loaded,
513 * it is possible that prog->instances.nr == -1.
514 */
515 if (prog->instances.nr > 0) {
516 for (i = 0; i < prog->instances.nr; i++)
517 zclose(prog->instances.fds[i]);
518 } else if (prog->instances.nr != -1) {
519 pr_warn("Internal error: instances.nr is %d\n",
520 prog->instances.nr);
521 }
522
523 prog->instances.nr = -1;
524 zfree(&prog->instances.fds);
525
526 zfree(&prog->func_info);
527 zfree(&prog->line_info);
528 }
529
bpf_program__exit(struct bpf_program * prog)530 static void bpf_program__exit(struct bpf_program *prog)
531 {
532 if (!prog)
533 return;
534
535 if (prog->clear_priv)
536 prog->clear_priv(prog, prog->priv);
537
538 prog->priv = NULL;
539 prog->clear_priv = NULL;
540
541 bpf_program__unload(prog);
542 zfree(&prog->name);
543 zfree(&prog->sec_name);
544 zfree(&prog->pin_name);
545 zfree(&prog->insns);
546 zfree(&prog->reloc_desc);
547
548 prog->nr_reloc = 0;
549 prog->insns_cnt = 0;
550 prog->sec_idx = -1;
551 }
552
__bpf_program__pin_name(struct bpf_program * prog)553 static char *__bpf_program__pin_name(struct bpf_program *prog)
554 {
555 char *name, *p;
556
557 name = p = strdup(prog->sec_name);
558 while ((p = strchr(p, '/')))
559 *p = '_';
560
561 return name;
562 }
563
insn_is_subprog_call(const struct bpf_insn * insn)564 static bool insn_is_subprog_call(const struct bpf_insn *insn)
565 {
566 return BPF_CLASS(insn->code) == BPF_JMP &&
567 BPF_OP(insn->code) == BPF_CALL &&
568 BPF_SRC(insn->code) == BPF_K &&
569 insn->src_reg == BPF_PSEUDO_CALL &&
570 insn->dst_reg == 0 &&
571 insn->off == 0;
572 }
573
is_ldimm64_insn(struct bpf_insn * insn)574 static bool is_ldimm64_insn(struct bpf_insn *insn)
575 {
576 return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
577 }
578
is_call_insn(const struct bpf_insn * insn)579 static bool is_call_insn(const struct bpf_insn *insn)
580 {
581 return insn->code == (BPF_JMP | BPF_CALL);
582 }
583
insn_is_pseudo_func(struct bpf_insn * insn)584 static bool insn_is_pseudo_func(struct bpf_insn *insn)
585 {
586 return is_ldimm64_insn(insn) && insn->src_reg == BPF_PSEUDO_FUNC;
587 }
588
589 static int
bpf_object__init_prog(struct bpf_object * obj,struct bpf_program * prog,const char * name,size_t sec_idx,const char * sec_name,size_t sec_off,void * insn_data,size_t insn_data_sz)590 bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
591 const char *name, size_t sec_idx, const char *sec_name,
592 size_t sec_off, void *insn_data, size_t insn_data_sz)
593 {
594 if (insn_data_sz == 0 || insn_data_sz % BPF_INSN_SZ || sec_off % BPF_INSN_SZ) {
595 pr_warn("sec '%s': corrupted program '%s', offset %zu, size %zu\n",
596 sec_name, name, sec_off, insn_data_sz);
597 return -EINVAL;
598 }
599
600 memset(prog, 0, sizeof(*prog));
601 prog->obj = obj;
602
603 prog->sec_idx = sec_idx;
604 prog->sec_insn_off = sec_off / BPF_INSN_SZ;
605 prog->sec_insn_cnt = insn_data_sz / BPF_INSN_SZ;
606 /* insns_cnt can later be increased by appending used subprograms */
607 prog->insns_cnt = prog->sec_insn_cnt;
608
609 prog->type = BPF_PROG_TYPE_UNSPEC;
610 prog->load = true;
611
612 prog->instances.fds = NULL;
613 prog->instances.nr = -1;
614
615 prog->sec_name = strdup(sec_name);
616 if (!prog->sec_name)
617 goto errout;
618
619 prog->name = strdup(name);
620 if (!prog->name)
621 goto errout;
622
623 prog->pin_name = __bpf_program__pin_name(prog);
624 if (!prog->pin_name)
625 goto errout;
626
627 prog->insns = malloc(insn_data_sz);
628 if (!prog->insns)
629 goto errout;
630 memcpy(prog->insns, insn_data, insn_data_sz);
631
632 return 0;
633 errout:
634 pr_warn("sec '%s': failed to allocate memory for prog '%s'\n", sec_name, name);
635 bpf_program__exit(prog);
636 return -ENOMEM;
637 }
638
639 static int
bpf_object__add_programs(struct bpf_object * obj,Elf_Data * sec_data,const char * sec_name,int sec_idx)640 bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
641 const char *sec_name, int sec_idx)
642 {
643 Elf_Data *symbols = obj->efile.symbols;
644 struct bpf_program *prog, *progs;
645 void *data = sec_data->d_buf;
646 size_t sec_sz = sec_data->d_size, sec_off, prog_sz, nr_syms;
647 int nr_progs, err, i;
648 const char *name;
649 GElf_Sym sym;
650
651 progs = obj->programs;
652 nr_progs = obj->nr_programs;
653 nr_syms = symbols->d_size / sizeof(GElf_Sym);
654 sec_off = 0;
655
656 for (i = 0; i < nr_syms; i++) {
657 if (!gelf_getsym(symbols, i, &sym))
658 continue;
659 if (sym.st_shndx != sec_idx)
660 continue;
661 if (GELF_ST_TYPE(sym.st_info) != STT_FUNC)
662 continue;
663
664 prog_sz = sym.st_size;
665 sec_off = sym.st_value;
666
667 name = elf_sym_str(obj, sym.st_name);
668 if (!name) {
669 pr_warn("sec '%s': failed to get symbol name for offset %zu\n",
670 sec_name, sec_off);
671 return -LIBBPF_ERRNO__FORMAT;
672 }
673
674 if (sec_off + prog_sz > sec_sz) {
675 pr_warn("sec '%s': program at offset %zu crosses section boundary\n",
676 sec_name, sec_off);
677 return -LIBBPF_ERRNO__FORMAT;
678 }
679
680 pr_debug("sec '%s': found program '%s' at insn offset %zu (%zu bytes), code size %zu insns (%zu bytes)\n",
681 sec_name, name, sec_off / BPF_INSN_SZ, sec_off, prog_sz / BPF_INSN_SZ, prog_sz);
682
683 progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(*progs));
684 if (!progs) {
685 /*
686 * In this case the original obj->programs
687 * is still valid, so don't need special treat for
688 * bpf_close_object().
689 */
690 pr_warn("sec '%s': failed to alloc memory for new program '%s'\n",
691 sec_name, name);
692 return -ENOMEM;
693 }
694 obj->programs = progs;
695
696 prog = &progs[nr_progs];
697
698 err = bpf_object__init_prog(obj, prog, name, sec_idx, sec_name,
699 sec_off, data + sec_off, prog_sz);
700 if (err)
701 return err;
702
703 /* if function is a global/weak symbol, but has hidden
704 * visibility (STV_HIDDEN), mark its BTF FUNC as static to
705 * enable more permissive BPF verification mode with more
706 * outside context available to BPF verifier
707 */
708 if (GELF_ST_BIND(sym.st_info) != STB_LOCAL
709 && GELF_ST_VISIBILITY(sym.st_other) == STV_HIDDEN)
710 prog->mark_btf_static = true;
711
712 nr_progs++;
713 obj->nr_programs = nr_progs;
714 }
715
716 return 0;
717 }
718
get_kernel_version(void)719 static __u32 get_kernel_version(void)
720 {
721 __u32 major, minor, patch;
722 struct utsname info;
723
724 uname(&info);
725 if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
726 return 0;
727 return KERNEL_VERSION(major, minor, patch);
728 }
729
730 static const struct btf_member *
find_member_by_offset(const struct btf_type * t,__u32 bit_offset)731 find_member_by_offset(const struct btf_type *t, __u32 bit_offset)
732 {
733 struct btf_member *m;
734 int i;
735
736 for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
737 if (btf_member_bit_offset(t, i) == bit_offset)
738 return m;
739 }
740
741 return NULL;
742 }
743
744 static const struct btf_member *
find_member_by_name(const struct btf * btf,const struct btf_type * t,const char * name)745 find_member_by_name(const struct btf *btf, const struct btf_type *t,
746 const char *name)
747 {
748 struct btf_member *m;
749 int i;
750
751 for (i = 0, m = btf_members(t); i < btf_vlen(t); i++, m++) {
752 if (!strcmp(btf__name_by_offset(btf, m->name_off), name))
753 return m;
754 }
755
756 return NULL;
757 }
758
759 #define STRUCT_OPS_VALUE_PREFIX "bpf_struct_ops_"
760 static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
761 const char *name, __u32 kind);
762
763 static int
find_struct_ops_kern_types(const struct btf * btf,const char * tname,const struct btf_type ** type,__u32 * type_id,const struct btf_type ** vtype,__u32 * vtype_id,const struct btf_member ** data_member)764 find_struct_ops_kern_types(const struct btf *btf, const char *tname,
765 const struct btf_type **type, __u32 *type_id,
766 const struct btf_type **vtype, __u32 *vtype_id,
767 const struct btf_member **data_member)
768 {
769 const struct btf_type *kern_type, *kern_vtype;
770 const struct btf_member *kern_data_member;
771 __s32 kern_vtype_id, kern_type_id;
772 __u32 i;
773
774 kern_type_id = btf__find_by_name_kind(btf, tname, BTF_KIND_STRUCT);
775 if (kern_type_id < 0) {
776 pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
777 tname);
778 return kern_type_id;
779 }
780 kern_type = btf__type_by_id(btf, kern_type_id);
781
782 /* Find the corresponding "map_value" type that will be used
783 * in map_update(BPF_MAP_TYPE_STRUCT_OPS). For example,
784 * find "struct bpf_struct_ops_tcp_congestion_ops" from the
785 * btf_vmlinux.
786 */
787 kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
788 tname, BTF_KIND_STRUCT);
789 if (kern_vtype_id < 0) {
790 pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
791 STRUCT_OPS_VALUE_PREFIX, tname);
792 return kern_vtype_id;
793 }
794 kern_vtype = btf__type_by_id(btf, kern_vtype_id);
795
796 /* Find "struct tcp_congestion_ops" from
797 * struct bpf_struct_ops_tcp_congestion_ops {
798 * [ ... ]
799 * struct tcp_congestion_ops data;
800 * }
801 */
802 kern_data_member = btf_members(kern_vtype);
803 for (i = 0; i < btf_vlen(kern_vtype); i++, kern_data_member++) {
804 if (kern_data_member->type == kern_type_id)
805 break;
806 }
807 if (i == btf_vlen(kern_vtype)) {
808 pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
809 tname, STRUCT_OPS_VALUE_PREFIX, tname);
810 return -EINVAL;
811 }
812
813 *type = kern_type;
814 *type_id = kern_type_id;
815 *vtype = kern_vtype;
816 *vtype_id = kern_vtype_id;
817 *data_member = kern_data_member;
818
819 return 0;
820 }
821
bpf_map__is_struct_ops(const struct bpf_map * map)822 static bool bpf_map__is_struct_ops(const struct bpf_map *map)
823 {
824 return map->def.type == BPF_MAP_TYPE_STRUCT_OPS;
825 }
826
827 /* Init the map's fields that depend on kern_btf */
bpf_map__init_kern_struct_ops(struct bpf_map * map,const struct btf * btf,const struct btf * kern_btf)828 static int bpf_map__init_kern_struct_ops(struct bpf_map *map,
829 const struct btf *btf,
830 const struct btf *kern_btf)
831 {
832 const struct btf_member *member, *kern_member, *kern_data_member;
833 const struct btf_type *type, *kern_type, *kern_vtype;
834 __u32 i, kern_type_id, kern_vtype_id, kern_data_off;
835 struct bpf_struct_ops *st_ops;
836 void *data, *kern_data;
837 const char *tname;
838 int err;
839
840 st_ops = map->st_ops;
841 type = st_ops->type;
842 tname = st_ops->tname;
843 err = find_struct_ops_kern_types(kern_btf, tname,
844 &kern_type, &kern_type_id,
845 &kern_vtype, &kern_vtype_id,
846 &kern_data_member);
847 if (err)
848 return err;
849
850 pr_debug("struct_ops init_kern %s: type_id:%u kern_type_id:%u kern_vtype_id:%u\n",
851 map->name, st_ops->type_id, kern_type_id, kern_vtype_id);
852
853 map->def.value_size = kern_vtype->size;
854 map->btf_vmlinux_value_type_id = kern_vtype_id;
855
856 st_ops->kern_vdata = calloc(1, kern_vtype->size);
857 if (!st_ops->kern_vdata)
858 return -ENOMEM;
859
860 data = st_ops->data;
861 kern_data_off = kern_data_member->offset / 8;
862 kern_data = st_ops->kern_vdata + kern_data_off;
863
864 member = btf_members(type);
865 for (i = 0; i < btf_vlen(type); i++, member++) {
866 const struct btf_type *mtype, *kern_mtype;
867 __u32 mtype_id, kern_mtype_id;
868 void *mdata, *kern_mdata;
869 __s64 msize, kern_msize;
870 __u32 moff, kern_moff;
871 __u32 kern_member_idx;
872 const char *mname;
873
874 mname = btf__name_by_offset(btf, member->name_off);
875 kern_member = find_member_by_name(kern_btf, kern_type, mname);
876 if (!kern_member) {
877 pr_warn("struct_ops init_kern %s: Cannot find member %s in kernel BTF\n",
878 map->name, mname);
879 return -ENOTSUP;
880 }
881
882 kern_member_idx = kern_member - btf_members(kern_type);
883 if (btf_member_bitfield_size(type, i) ||
884 btf_member_bitfield_size(kern_type, kern_member_idx)) {
885 pr_warn("struct_ops init_kern %s: bitfield %s is not supported\n",
886 map->name, mname);
887 return -ENOTSUP;
888 }
889
890 moff = member->offset / 8;
891 kern_moff = kern_member->offset / 8;
892
893 mdata = data + moff;
894 kern_mdata = kern_data + kern_moff;
895
896 mtype = skip_mods_and_typedefs(btf, member->type, &mtype_id);
897 kern_mtype = skip_mods_and_typedefs(kern_btf, kern_member->type,
898 &kern_mtype_id);
899 if (BTF_INFO_KIND(mtype->info) !=
900 BTF_INFO_KIND(kern_mtype->info)) {
901 pr_warn("struct_ops init_kern %s: Unmatched member type %s %u != %u(kernel)\n",
902 map->name, mname, BTF_INFO_KIND(mtype->info),
903 BTF_INFO_KIND(kern_mtype->info));
904 return -ENOTSUP;
905 }
906
907 if (btf_is_ptr(mtype)) {
908 struct bpf_program *prog;
909
910 prog = st_ops->progs[i];
911 if (!prog)
912 continue;
913
914 kern_mtype = skip_mods_and_typedefs(kern_btf,
915 kern_mtype->type,
916 &kern_mtype_id);
917
918 /* mtype->type must be a func_proto which was
919 * guaranteed in bpf_object__collect_st_ops_relos(),
920 * so only check kern_mtype for func_proto here.
921 */
922 if (!btf_is_func_proto(kern_mtype)) {
923 pr_warn("struct_ops init_kern %s: kernel member %s is not a func ptr\n",
924 map->name, mname);
925 return -ENOTSUP;
926 }
927
928 prog->attach_btf_id = kern_type_id;
929 prog->expected_attach_type = kern_member_idx;
930
931 st_ops->kern_func_off[i] = kern_data_off + kern_moff;
932
933 pr_debug("struct_ops init_kern %s: func ptr %s is set to prog %s from data(+%u) to kern_data(+%u)\n",
934 map->name, mname, prog->name, moff,
935 kern_moff);
936
937 continue;
938 }
939
940 msize = btf__resolve_size(btf, mtype_id);
941 kern_msize = btf__resolve_size(kern_btf, kern_mtype_id);
942 if (msize < 0 || kern_msize < 0 || msize != kern_msize) {
943 pr_warn("struct_ops init_kern %s: Error in size of member %s: %zd != %zd(kernel)\n",
944 map->name, mname, (ssize_t)msize,
945 (ssize_t)kern_msize);
946 return -ENOTSUP;
947 }
948
949 pr_debug("struct_ops init_kern %s: copy %s %u bytes from data(+%u) to kern_data(+%u)\n",
950 map->name, mname, (unsigned int)msize,
951 moff, kern_moff);
952 memcpy(kern_mdata, mdata, msize);
953 }
954
955 return 0;
956 }
957
bpf_object__init_kern_struct_ops_maps(struct bpf_object * obj)958 static int bpf_object__init_kern_struct_ops_maps(struct bpf_object *obj)
959 {
960 struct bpf_map *map;
961 size_t i;
962 int err;
963
964 for (i = 0; i < obj->nr_maps; i++) {
965 map = &obj->maps[i];
966
967 if (!bpf_map__is_struct_ops(map))
968 continue;
969
970 err = bpf_map__init_kern_struct_ops(map, obj->btf,
971 obj->btf_vmlinux);
972 if (err)
973 return err;
974 }
975
976 return 0;
977 }
978
bpf_object__init_struct_ops_maps(struct bpf_object * obj)979 static int bpf_object__init_struct_ops_maps(struct bpf_object *obj)
980 {
981 const struct btf_type *type, *datasec;
982 const struct btf_var_secinfo *vsi;
983 struct bpf_struct_ops *st_ops;
984 const char *tname, *var_name;
985 __s32 type_id, datasec_id;
986 const struct btf *btf;
987 struct bpf_map *map;
988 __u32 i;
989
990 if (obj->efile.st_ops_shndx == -1)
991 return 0;
992
993 btf = obj->btf;
994 datasec_id = btf__find_by_name_kind(btf, STRUCT_OPS_SEC,
995 BTF_KIND_DATASEC);
996 if (datasec_id < 0) {
997 pr_warn("struct_ops init: DATASEC %s not found\n",
998 STRUCT_OPS_SEC);
999 return -EINVAL;
1000 }
1001
1002 datasec = btf__type_by_id(btf, datasec_id);
1003 vsi = btf_var_secinfos(datasec);
1004 for (i = 0; i < btf_vlen(datasec); i++, vsi++) {
1005 type = btf__type_by_id(obj->btf, vsi->type);
1006 var_name = btf__name_by_offset(obj->btf, type->name_off);
1007
1008 type_id = btf__resolve_type(obj->btf, vsi->type);
1009 if (type_id < 0) {
1010 pr_warn("struct_ops init: Cannot resolve var type_id %u in DATASEC %s\n",
1011 vsi->type, STRUCT_OPS_SEC);
1012 return -EINVAL;
1013 }
1014
1015 type = btf__type_by_id(obj->btf, type_id);
1016 tname = btf__name_by_offset(obj->btf, type->name_off);
1017 if (!tname[0]) {
1018 pr_warn("struct_ops init: anonymous type is not supported\n");
1019 return -ENOTSUP;
1020 }
1021 if (!btf_is_struct(type)) {
1022 pr_warn("struct_ops init: %s is not a struct\n", tname);
1023 return -EINVAL;
1024 }
1025
1026 map = bpf_object__add_map(obj);
1027 if (IS_ERR(map))
1028 return PTR_ERR(map);
1029
1030 map->sec_idx = obj->efile.st_ops_shndx;
1031 map->sec_offset = vsi->offset;
1032 map->name = strdup(var_name);
1033 if (!map->name)
1034 return -ENOMEM;
1035
1036 map->def.type = BPF_MAP_TYPE_STRUCT_OPS;
1037 map->def.key_size = sizeof(int);
1038 map->def.value_size = type->size;
1039 map->def.max_entries = 1;
1040
1041 map->st_ops = calloc(1, sizeof(*map->st_ops));
1042 if (!map->st_ops)
1043 return -ENOMEM;
1044 st_ops = map->st_ops;
1045 st_ops->data = malloc(type->size);
1046 st_ops->progs = calloc(btf_vlen(type), sizeof(*st_ops->progs));
1047 st_ops->kern_func_off = malloc(btf_vlen(type) *
1048 sizeof(*st_ops->kern_func_off));
1049 if (!st_ops->data || !st_ops->progs || !st_ops->kern_func_off)
1050 return -ENOMEM;
1051
1052 if (vsi->offset + type->size > obj->efile.st_ops_data->d_size) {
1053 pr_warn("struct_ops init: var %s is beyond the end of DATASEC %s\n",
1054 var_name, STRUCT_OPS_SEC);
1055 return -EINVAL;
1056 }
1057
1058 memcpy(st_ops->data,
1059 obj->efile.st_ops_data->d_buf + vsi->offset,
1060 type->size);
1061 st_ops->tname = tname;
1062 st_ops->type = type;
1063 st_ops->type_id = type_id;
1064
1065 pr_debug("struct_ops init: struct %s(type_id=%u) %s found at offset %u\n",
1066 tname, type_id, var_name, vsi->offset);
1067 }
1068
1069 return 0;
1070 }
1071
bpf_object__new(const char * path,const void * obj_buf,size_t obj_buf_sz,const char * obj_name)1072 static struct bpf_object *bpf_object__new(const char *path,
1073 const void *obj_buf,
1074 size_t obj_buf_sz,
1075 const char *obj_name)
1076 {
1077 struct bpf_object *obj;
1078 char *end;
1079
1080 obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
1081 if (!obj) {
1082 pr_warn("alloc memory failed for %s\n", path);
1083 return ERR_PTR(-ENOMEM);
1084 }
1085
1086 strcpy(obj->path, path);
1087 if (obj_name) {
1088 strncpy(obj->name, obj_name, sizeof(obj->name) - 1);
1089 obj->name[sizeof(obj->name) - 1] = 0;
1090 } else {
1091 /* Using basename() GNU version which doesn't modify arg. */
1092 strncpy(obj->name, basename((void *)path),
1093 sizeof(obj->name) - 1);
1094 end = strchr(obj->name, '.');
1095 if (end)
1096 *end = 0;
1097 }
1098
1099 obj->efile.fd = -1;
1100 /*
1101 * Caller of this function should also call
1102 * bpf_object__elf_finish() after data collection to return
1103 * obj_buf to user. If not, we should duplicate the buffer to
1104 * avoid user freeing them before elf finish.
1105 */
1106 obj->efile.obj_buf = obj_buf;
1107 obj->efile.obj_buf_sz = obj_buf_sz;
1108 obj->efile.maps_shndx = -1;
1109 obj->efile.btf_maps_shndx = -1;
1110 obj->efile.data_shndx = -1;
1111 obj->efile.rodata_shndx = -1;
1112 obj->efile.bss_shndx = -1;
1113 obj->efile.st_ops_shndx = -1;
1114 obj->kconfig_map_idx = -1;
1115 obj->rodata_map_idx = -1;
1116
1117 obj->kern_version = get_kernel_version();
1118 obj->loaded = false;
1119
1120 INIT_LIST_HEAD(&obj->list);
1121 list_add(&obj->list, &bpf_objects_list);
1122 return obj;
1123 }
1124
bpf_object__elf_finish(struct bpf_object * obj)1125 static void bpf_object__elf_finish(struct bpf_object *obj)
1126 {
1127 if (!obj_elf_valid(obj))
1128 return;
1129
1130 if (obj->efile.elf) {
1131 elf_end(obj->efile.elf);
1132 obj->efile.elf = NULL;
1133 }
1134 obj->efile.symbols = NULL;
1135 obj->efile.data = NULL;
1136 obj->efile.rodata = NULL;
1137 obj->efile.bss = NULL;
1138 obj->efile.st_ops_data = NULL;
1139
1140 zfree(&obj->efile.reloc_sects);
1141 obj->efile.nr_reloc_sects = 0;
1142 zclose(obj->efile.fd);
1143 obj->efile.obj_buf = NULL;
1144 obj->efile.obj_buf_sz = 0;
1145 }
1146
bpf_object__elf_init(struct bpf_object * obj)1147 static int bpf_object__elf_init(struct bpf_object *obj)
1148 {
1149 int err = 0;
1150 GElf_Ehdr *ep;
1151
1152 if (obj_elf_valid(obj)) {
1153 pr_warn("elf: init internal error\n");
1154 return -LIBBPF_ERRNO__LIBELF;
1155 }
1156
1157 if (obj->efile.obj_buf_sz > 0) {
1158 /*
1159 * obj_buf should have been validated by
1160 * bpf_object__open_buffer().
1161 */
1162 obj->efile.elf = elf_memory((char *)obj->efile.obj_buf,
1163 obj->efile.obj_buf_sz);
1164 } else {
1165 obj->efile.fd = open(obj->path, O_RDONLY);
1166 if (obj->efile.fd < 0) {
1167 char errmsg[STRERR_BUFSIZE], *cp;
1168
1169 err = -errno;
1170 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
1171 pr_warn("elf: failed to open %s: %s\n", obj->path, cp);
1172 return err;
1173 }
1174
1175 obj->efile.elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
1176 }
1177
1178 if (!obj->efile.elf) {
1179 pr_warn("elf: failed to open %s as ELF file: %s\n", obj->path, elf_errmsg(-1));
1180 err = -LIBBPF_ERRNO__LIBELF;
1181 goto errout;
1182 }
1183
1184 if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
1185 pr_warn("elf: failed to get ELF header from %s: %s\n", obj->path, elf_errmsg(-1));
1186 err = -LIBBPF_ERRNO__FORMAT;
1187 goto errout;
1188 }
1189 ep = &obj->efile.ehdr;
1190
1191 if (elf_getshdrstrndx(obj->efile.elf, &obj->efile.shstrndx)) {
1192 pr_warn("elf: failed to get section names section index for %s: %s\n",
1193 obj->path, elf_errmsg(-1));
1194 err = -LIBBPF_ERRNO__FORMAT;
1195 goto errout;
1196 }
1197
1198 /* Elf is corrupted/truncated, avoid calling elf_strptr. */
1199 if (!elf_rawdata(elf_getscn(obj->efile.elf, obj->efile.shstrndx), NULL)) {
1200 pr_warn("elf: failed to get section names strings from %s: %s\n",
1201 obj->path, elf_errmsg(-1));
1202 err = -LIBBPF_ERRNO__FORMAT;
1203 goto errout;
1204 }
1205
1206 /* Old LLVM set e_machine to EM_NONE */
1207 if (ep->e_type != ET_REL ||
1208 (ep->e_machine && ep->e_machine != EM_BPF)) {
1209 pr_warn("elf: %s is not a valid eBPF object file\n", obj->path);
1210 err = -LIBBPF_ERRNO__FORMAT;
1211 goto errout;
1212 }
1213
1214 return 0;
1215 errout:
1216 bpf_object__elf_finish(obj);
1217 return err;
1218 }
1219
bpf_object__check_endianness(struct bpf_object * obj)1220 static int bpf_object__check_endianness(struct bpf_object *obj)
1221 {
1222 #if __BYTE_ORDER == __LITTLE_ENDIAN
1223 if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
1224 return 0;
1225 #elif __BYTE_ORDER == __BIG_ENDIAN
1226 if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
1227 return 0;
1228 #else
1229 # error "Unrecognized __BYTE_ORDER__"
1230 #endif
1231 pr_warn("elf: endianness mismatch in %s.\n", obj->path);
1232 return -LIBBPF_ERRNO__ENDIAN;
1233 }
1234
1235 static int
bpf_object__init_license(struct bpf_object * obj,void * data,size_t size)1236 bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
1237 {
1238 memcpy(obj->license, data, min(size, sizeof(obj->license) - 1));
1239 pr_debug("license of %s is %s\n", obj->path, obj->license);
1240 return 0;
1241 }
1242
1243 static int
bpf_object__init_kversion(struct bpf_object * obj,void * data,size_t size)1244 bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
1245 {
1246 __u32 kver;
1247
1248 if (size != sizeof(kver)) {
1249 pr_warn("invalid kver section in %s\n", obj->path);
1250 return -LIBBPF_ERRNO__FORMAT;
1251 }
1252 memcpy(&kver, data, sizeof(kver));
1253 obj->kern_version = kver;
1254 pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
1255 return 0;
1256 }
1257
bpf_map_type__is_map_in_map(enum bpf_map_type type)1258 static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
1259 {
1260 if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
1261 type == BPF_MAP_TYPE_HASH_OF_MAPS)
1262 return true;
1263 return false;
1264 }
1265
bpf_object__section_size(const struct bpf_object * obj,const char * name,__u32 * size)1266 int bpf_object__section_size(const struct bpf_object *obj, const char *name,
1267 __u32 *size)
1268 {
1269 int ret = -ENOENT;
1270
1271 *size = 0;
1272 if (!name) {
1273 return -EINVAL;
1274 } else if (!strcmp(name, DATA_SEC)) {
1275 if (obj->efile.data)
1276 *size = obj->efile.data->d_size;
1277 } else if (!strcmp(name, BSS_SEC)) {
1278 if (obj->efile.bss)
1279 *size = obj->efile.bss->d_size;
1280 } else if (!strcmp(name, RODATA_SEC)) {
1281 if (obj->efile.rodata)
1282 *size = obj->efile.rodata->d_size;
1283 } else if (!strcmp(name, STRUCT_OPS_SEC)) {
1284 if (obj->efile.st_ops_data)
1285 *size = obj->efile.st_ops_data->d_size;
1286 } else {
1287 Elf_Scn *scn = elf_sec_by_name(obj, name);
1288 Elf_Data *data = elf_sec_data(obj, scn);
1289
1290 if (data) {
1291 ret = 0; /* found it */
1292 *size = data->d_size;
1293 }
1294 }
1295
1296 return *size ? 0 : ret;
1297 }
1298
bpf_object__variable_offset(const struct bpf_object * obj,const char * name,__u32 * off)1299 int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
1300 __u32 *off)
1301 {
1302 Elf_Data *symbols = obj->efile.symbols;
1303 const char *sname;
1304 size_t si;
1305
1306 if (!name || !off)
1307 return -EINVAL;
1308
1309 for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) {
1310 GElf_Sym sym;
1311
1312 if (!gelf_getsym(symbols, si, &sym))
1313 continue;
1314 if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL ||
1315 GELF_ST_TYPE(sym.st_info) != STT_OBJECT)
1316 continue;
1317
1318 sname = elf_sym_str(obj, sym.st_name);
1319 if (!sname) {
1320 pr_warn("failed to get sym name string for var %s\n",
1321 name);
1322 return -EIO;
1323 }
1324 if (strcmp(name, sname) == 0) {
1325 *off = sym.st_value;
1326 return 0;
1327 }
1328 }
1329
1330 return -ENOENT;
1331 }
1332
bpf_object__add_map(struct bpf_object * obj)1333 static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
1334 {
1335 struct bpf_map *new_maps;
1336 size_t new_cap;
1337 int i;
1338
1339 if (obj->nr_maps < obj->maps_cap)
1340 return &obj->maps[obj->nr_maps++];
1341
1342 new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
1343 new_maps = libbpf_reallocarray(obj->maps, new_cap, sizeof(*obj->maps));
1344 if (!new_maps) {
1345 pr_warn("alloc maps for object failed\n");
1346 return ERR_PTR(-ENOMEM);
1347 }
1348
1349 obj->maps_cap = new_cap;
1350 obj->maps = new_maps;
1351
1352 /* zero out new maps */
1353 memset(obj->maps + obj->nr_maps, 0,
1354 (obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps));
1355 /*
1356 * fill all fd with -1 so won't close incorrect fd (fd=0 is stdin)
1357 * when failure (zclose won't close negative fd)).
1358 */
1359 for (i = obj->nr_maps; i < obj->maps_cap; i++) {
1360 obj->maps[i].fd = -1;
1361 obj->maps[i].inner_map_fd = -1;
1362 }
1363
1364 return &obj->maps[obj->nr_maps++];
1365 }
1366
bpf_map_mmap_sz(const struct bpf_map * map)1367 static size_t bpf_map_mmap_sz(const struct bpf_map *map)
1368 {
1369 long page_sz = sysconf(_SC_PAGE_SIZE);
1370 size_t map_sz;
1371
1372 map_sz = (size_t)roundup(map->def.value_size, 8) * map->def.max_entries;
1373 map_sz = roundup(map_sz, page_sz);
1374 return map_sz;
1375 }
1376
internal_map_name(struct bpf_object * obj,enum libbpf_map_type type)1377 static char *internal_map_name(struct bpf_object *obj,
1378 enum libbpf_map_type type)
1379 {
1380 char map_name[BPF_OBJ_NAME_LEN], *p;
1381 const char *sfx = libbpf_type_to_btf_name[type];
1382 int sfx_len = max((size_t)7, strlen(sfx));
1383 int pfx_len = min((size_t)BPF_OBJ_NAME_LEN - sfx_len - 1,
1384 strlen(obj->name));
1385
1386 snprintf(map_name, sizeof(map_name), "%.*s%.*s", pfx_len, obj->name,
1387 sfx_len, libbpf_type_to_btf_name[type]);
1388
1389 /* sanitise map name to characters allowed by kernel */
1390 for (p = map_name; *p && p < map_name + sizeof(map_name); p++)
1391 if (!isalnum(*p) && *p != '_' && *p != '.')
1392 *p = '_';
1393
1394 return strdup(map_name);
1395 }
1396
1397 static int
bpf_object__init_internal_map(struct bpf_object * obj,enum libbpf_map_type type,int sec_idx,void * data,size_t data_sz)1398 bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
1399 int sec_idx, void *data, size_t data_sz)
1400 {
1401 struct bpf_map_def *def;
1402 struct bpf_map *map;
1403 int err;
1404
1405 map = bpf_object__add_map(obj);
1406 if (IS_ERR(map))
1407 return PTR_ERR(map);
1408
1409 map->libbpf_type = type;
1410 map->sec_idx = sec_idx;
1411 map->sec_offset = 0;
1412 map->name = internal_map_name(obj, type);
1413 if (!map->name) {
1414 pr_warn("failed to alloc map name\n");
1415 return -ENOMEM;
1416 }
1417
1418 def = &map->def;
1419 def->type = BPF_MAP_TYPE_ARRAY;
1420 def->key_size = sizeof(int);
1421 def->value_size = data_sz;
1422 def->max_entries = 1;
1423 def->map_flags = type == LIBBPF_MAP_RODATA || type == LIBBPF_MAP_KCONFIG
1424 ? BPF_F_RDONLY_PROG : 0;
1425 def->map_flags |= BPF_F_MMAPABLE;
1426
1427 pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
1428 map->name, map->sec_idx, map->sec_offset, def->map_flags);
1429
1430 map->mmaped = mmap(NULL, bpf_map_mmap_sz(map), PROT_READ | PROT_WRITE,
1431 MAP_SHARED | MAP_ANONYMOUS, -1, 0);
1432 if (map->mmaped == MAP_FAILED) {
1433 err = -errno;
1434 map->mmaped = NULL;
1435 pr_warn("failed to alloc map '%s' content buffer: %d\n",
1436 map->name, err);
1437 zfree(&map->name);
1438 return err;
1439 }
1440
1441 if (data)
1442 memcpy(map->mmaped, data, data_sz);
1443
1444 pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
1445 return 0;
1446 }
1447
bpf_object__init_global_data_maps(struct bpf_object * obj)1448 static int bpf_object__init_global_data_maps(struct bpf_object *obj)
1449 {
1450 int err;
1451
1452 /*
1453 * Populate obj->maps with libbpf internal maps.
1454 */
1455 if (obj->efile.data_shndx >= 0) {
1456 err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
1457 obj->efile.data_shndx,
1458 obj->efile.data->d_buf,
1459 obj->efile.data->d_size);
1460 if (err)
1461 return err;
1462 }
1463 if (obj->efile.rodata_shndx >= 0) {
1464 err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
1465 obj->efile.rodata_shndx,
1466 obj->efile.rodata->d_buf,
1467 obj->efile.rodata->d_size);
1468 if (err)
1469 return err;
1470
1471 obj->rodata_map_idx = obj->nr_maps - 1;
1472 }
1473 if (obj->efile.bss_shndx >= 0) {
1474 err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
1475 obj->efile.bss_shndx,
1476 NULL,
1477 obj->efile.bss->d_size);
1478 if (err)
1479 return err;
1480 }
1481 return 0;
1482 }
1483
1484
find_extern_by_name(const struct bpf_object * obj,const void * name)1485 static struct extern_desc *find_extern_by_name(const struct bpf_object *obj,
1486 const void *name)
1487 {
1488 int i;
1489
1490 for (i = 0; i < obj->nr_extern; i++) {
1491 if (strcmp(obj->externs[i].name, name) == 0)
1492 return &obj->externs[i];
1493 }
1494 return NULL;
1495 }
1496
set_kcfg_value_tri(struct extern_desc * ext,void * ext_val,char value)1497 static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
1498 char value)
1499 {
1500 switch (ext->kcfg.type) {
1501 case KCFG_BOOL:
1502 if (value == 'm') {
1503 pr_warn("extern (kcfg) %s=%c should be tristate or char\n",
1504 ext->name, value);
1505 return -EINVAL;
1506 }
1507 *(bool *)ext_val = value == 'y' ? true : false;
1508 break;
1509 case KCFG_TRISTATE:
1510 if (value == 'y')
1511 *(enum libbpf_tristate *)ext_val = TRI_YES;
1512 else if (value == 'm')
1513 *(enum libbpf_tristate *)ext_val = TRI_MODULE;
1514 else /* value == 'n' */
1515 *(enum libbpf_tristate *)ext_val = TRI_NO;
1516 break;
1517 case KCFG_CHAR:
1518 *(char *)ext_val = value;
1519 break;
1520 case KCFG_UNKNOWN:
1521 case KCFG_INT:
1522 case KCFG_CHAR_ARR:
1523 default:
1524 pr_warn("extern (kcfg) %s=%c should be bool, tristate, or char\n",
1525 ext->name, value);
1526 return -EINVAL;
1527 }
1528 ext->is_set = true;
1529 return 0;
1530 }
1531
set_kcfg_value_str(struct extern_desc * ext,char * ext_val,const char * value)1532 static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
1533 const char *value)
1534 {
1535 size_t len;
1536
1537 if (ext->kcfg.type != KCFG_CHAR_ARR) {
1538 pr_warn("extern (kcfg) %s=%s should be char array\n", ext->name, value);
1539 return -EINVAL;
1540 }
1541
1542 len = strlen(value);
1543 if (value[len - 1] != '"') {
1544 pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
1545 ext->name, value);
1546 return -EINVAL;
1547 }
1548
1549 /* strip quotes */
1550 len -= 2;
1551 if (len >= ext->kcfg.sz) {
1552 pr_warn("extern (kcfg) '%s': long string config %s of (%zu bytes) truncated to %d bytes\n",
1553 ext->name, value, len, ext->kcfg.sz - 1);
1554 len = ext->kcfg.sz - 1;
1555 }
1556 memcpy(ext_val, value + 1, len);
1557 ext_val[len] = '\0';
1558 ext->is_set = true;
1559 return 0;
1560 }
1561
parse_u64(const char * value,__u64 * res)1562 static int parse_u64(const char *value, __u64 *res)
1563 {
1564 char *value_end;
1565 int err;
1566
1567 errno = 0;
1568 *res = strtoull(value, &value_end, 0);
1569 if (errno) {
1570 err = -errno;
1571 pr_warn("failed to parse '%s' as integer: %d\n", value, err);
1572 return err;
1573 }
1574 if (*value_end) {
1575 pr_warn("failed to parse '%s' as integer completely\n", value);
1576 return -EINVAL;
1577 }
1578 return 0;
1579 }
1580
is_kcfg_value_in_range(const struct extern_desc * ext,__u64 v)1581 static bool is_kcfg_value_in_range(const struct extern_desc *ext, __u64 v)
1582 {
1583 int bit_sz = ext->kcfg.sz * 8;
1584
1585 if (ext->kcfg.sz == 8)
1586 return true;
1587
1588 /* Validate that value stored in u64 fits in integer of `ext->sz`
1589 * bytes size without any loss of information. If the target integer
1590 * is signed, we rely on the following limits of integer type of
1591 * Y bits and subsequent transformation:
1592 *
1593 * -2^(Y-1) <= X <= 2^(Y-1) - 1
1594 * 0 <= X + 2^(Y-1) <= 2^Y - 1
1595 * 0 <= X + 2^(Y-1) < 2^Y
1596 *
1597 * For unsigned target integer, check that all the (64 - Y) bits are
1598 * zero.
1599 */
1600 if (ext->kcfg.is_signed)
1601 return v + (1ULL << (bit_sz - 1)) < (1ULL << bit_sz);
1602 else
1603 return (v >> bit_sz) == 0;
1604 }
1605
set_kcfg_value_num(struct extern_desc * ext,void * ext_val,__u64 value)1606 static int set_kcfg_value_num(struct extern_desc *ext, void *ext_val,
1607 __u64 value)
1608 {
1609 if (ext->kcfg.type != KCFG_INT && ext->kcfg.type != KCFG_CHAR) {
1610 pr_warn("extern (kcfg) %s=%llu should be integer\n",
1611 ext->name, (unsigned long long)value);
1612 return -EINVAL;
1613 }
1614 if (!is_kcfg_value_in_range(ext, value)) {
1615 pr_warn("extern (kcfg) %s=%llu value doesn't fit in %d bytes\n",
1616 ext->name, (unsigned long long)value, ext->kcfg.sz);
1617 return -ERANGE;
1618 }
1619 switch (ext->kcfg.sz) {
1620 case 1: *(__u8 *)ext_val = value; break;
1621 case 2: *(__u16 *)ext_val = value; break;
1622 case 4: *(__u32 *)ext_val = value; break;
1623 case 8: *(__u64 *)ext_val = value; break;
1624 default:
1625 return -EINVAL;
1626 }
1627 ext->is_set = true;
1628 return 0;
1629 }
1630
bpf_object__process_kconfig_line(struct bpf_object * obj,char * buf,void * data)1631 static int bpf_object__process_kconfig_line(struct bpf_object *obj,
1632 char *buf, void *data)
1633 {
1634 struct extern_desc *ext;
1635 char *sep, *value;
1636 int len, err = 0;
1637 void *ext_val;
1638 __u64 num;
1639
1640 if (strncmp(buf, "CONFIG_", 7))
1641 return 0;
1642
1643 sep = strchr(buf, '=');
1644 if (!sep) {
1645 pr_warn("failed to parse '%s': no separator\n", buf);
1646 return -EINVAL;
1647 }
1648
1649 /* Trim ending '\n' */
1650 len = strlen(buf);
1651 if (buf[len - 1] == '\n')
1652 buf[len - 1] = '\0';
1653 /* Split on '=' and ensure that a value is present. */
1654 *sep = '\0';
1655 if (!sep[1]) {
1656 *sep = '=';
1657 pr_warn("failed to parse '%s': no value\n", buf);
1658 return -EINVAL;
1659 }
1660
1661 ext = find_extern_by_name(obj, buf);
1662 if (!ext || ext->is_set)
1663 return 0;
1664
1665 ext_val = data + ext->kcfg.data_off;
1666 value = sep + 1;
1667
1668 switch (*value) {
1669 case 'y': case 'n': case 'm':
1670 err = set_kcfg_value_tri(ext, ext_val, *value);
1671 break;
1672 case '"':
1673 err = set_kcfg_value_str(ext, ext_val, value);
1674 break;
1675 default:
1676 /* assume integer */
1677 err = parse_u64(value, &num);
1678 if (err) {
1679 pr_warn("extern (kcfg) %s=%s should be integer\n",
1680 ext->name, value);
1681 return err;
1682 }
1683 err = set_kcfg_value_num(ext, ext_val, num);
1684 break;
1685 }
1686 if (err)
1687 return err;
1688 pr_debug("extern (kcfg) %s=%s\n", ext->name, value);
1689 return 0;
1690 }
1691
bpf_object__read_kconfig_file(struct bpf_object * obj,void * data)1692 static int bpf_object__read_kconfig_file(struct bpf_object *obj, void *data)
1693 {
1694 char buf[PATH_MAX];
1695 struct utsname uts;
1696 int len, err = 0;
1697 gzFile file;
1698
1699 uname(&uts);
1700 len = snprintf(buf, PATH_MAX, "/boot/config-%s", uts.release);
1701 if (len < 0)
1702 return -EINVAL;
1703 else if (len >= PATH_MAX)
1704 return -ENAMETOOLONG;
1705
1706 /* gzopen also accepts uncompressed files. */
1707 file = gzopen(buf, "r");
1708 if (!file)
1709 file = gzopen("/proc/config.gz", "r");
1710
1711 if (!file) {
1712 pr_warn("failed to open system Kconfig\n");
1713 return -ENOENT;
1714 }
1715
1716 while (gzgets(file, buf, sizeof(buf))) {
1717 err = bpf_object__process_kconfig_line(obj, buf, data);
1718 if (err) {
1719 pr_warn("error parsing system Kconfig line '%s': %d\n",
1720 buf, err);
1721 goto out;
1722 }
1723 }
1724
1725 out:
1726 gzclose(file);
1727 return err;
1728 }
1729
bpf_object__read_kconfig_mem(struct bpf_object * obj,const char * config,void * data)1730 static int bpf_object__read_kconfig_mem(struct bpf_object *obj,
1731 const char *config, void *data)
1732 {
1733 char buf[PATH_MAX];
1734 int err = 0;
1735 FILE *file;
1736
1737 file = fmemopen((void *)config, strlen(config), "r");
1738 if (!file) {
1739 err = -errno;
1740 pr_warn("failed to open in-memory Kconfig: %d\n", err);
1741 return err;
1742 }
1743
1744 while (fgets(buf, sizeof(buf), file)) {
1745 err = bpf_object__process_kconfig_line(obj, buf, data);
1746 if (err) {
1747 pr_warn("error parsing in-memory Kconfig line '%s': %d\n",
1748 buf, err);
1749 break;
1750 }
1751 }
1752
1753 fclose(file);
1754 return err;
1755 }
1756
bpf_object__init_kconfig_map(struct bpf_object * obj)1757 static int bpf_object__init_kconfig_map(struct bpf_object *obj)
1758 {
1759 struct extern_desc *last_ext = NULL, *ext;
1760 size_t map_sz;
1761 int i, err;
1762
1763 for (i = 0; i < obj->nr_extern; i++) {
1764 ext = &obj->externs[i];
1765 if (ext->type == EXT_KCFG)
1766 last_ext = ext;
1767 }
1768
1769 if (!last_ext)
1770 return 0;
1771
1772 map_sz = last_ext->kcfg.data_off + last_ext->kcfg.sz;
1773 err = bpf_object__init_internal_map(obj, LIBBPF_MAP_KCONFIG,
1774 obj->efile.symbols_shndx,
1775 NULL, map_sz);
1776 if (err)
1777 return err;
1778
1779 obj->kconfig_map_idx = obj->nr_maps - 1;
1780
1781 return 0;
1782 }
1783
bpf_object__init_user_maps(struct bpf_object * obj,bool strict)1784 static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
1785 {
1786 Elf_Data *symbols = obj->efile.symbols;
1787 int i, map_def_sz = 0, nr_maps = 0, nr_syms;
1788 Elf_Data *data = NULL;
1789 Elf_Scn *scn;
1790
1791 if (obj->efile.maps_shndx < 0)
1792 return 0;
1793
1794 if (!symbols)
1795 return -EINVAL;
1796
1797
1798 scn = elf_sec_by_idx(obj, obj->efile.maps_shndx);
1799 data = elf_sec_data(obj, scn);
1800 if (!scn || !data) {
1801 pr_warn("elf: failed to get legacy map definitions for %s\n",
1802 obj->path);
1803 return -EINVAL;
1804 }
1805
1806 /*
1807 * Count number of maps. Each map has a name.
1808 * Array of maps is not supported: only the first element is
1809 * considered.
1810 *
1811 * TODO: Detect array of map and report error.
1812 */
1813 nr_syms = symbols->d_size / sizeof(GElf_Sym);
1814 for (i = 0; i < nr_syms; i++) {
1815 GElf_Sym sym;
1816
1817 if (!gelf_getsym(symbols, i, &sym))
1818 continue;
1819 if (sym.st_shndx != obj->efile.maps_shndx)
1820 continue;
1821 nr_maps++;
1822 }
1823 /* Assume equally sized map definitions */
1824 pr_debug("elf: found %d legacy map definitions (%zd bytes) in %s\n",
1825 nr_maps, data->d_size, obj->path);
1826
1827 if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) {
1828 pr_warn("elf: unable to determine legacy map definition size in %s\n",
1829 obj->path);
1830 return -EINVAL;
1831 }
1832 map_def_sz = data->d_size / nr_maps;
1833
1834 /* Fill obj->maps using data in "maps" section. */
1835 for (i = 0; i < nr_syms; i++) {
1836 GElf_Sym sym;
1837 const char *map_name;
1838 struct bpf_map_def *def;
1839 struct bpf_map *map;
1840
1841 if (!gelf_getsym(symbols, i, &sym))
1842 continue;
1843 if (sym.st_shndx != obj->efile.maps_shndx)
1844 continue;
1845
1846 map = bpf_object__add_map(obj);
1847 if (IS_ERR(map))
1848 return PTR_ERR(map);
1849
1850 map_name = elf_sym_str(obj, sym.st_name);
1851 if (!map_name) {
1852 pr_warn("failed to get map #%d name sym string for obj %s\n",
1853 i, obj->path);
1854 return -LIBBPF_ERRNO__FORMAT;
1855 }
1856
1857 map->libbpf_type = LIBBPF_MAP_UNSPEC;
1858 map->sec_idx = sym.st_shndx;
1859 map->sec_offset = sym.st_value;
1860 pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n",
1861 map_name, map->sec_idx, map->sec_offset);
1862 if (sym.st_value + map_def_sz > data->d_size) {
1863 pr_warn("corrupted maps section in %s: last map \"%s\" too small\n",
1864 obj->path, map_name);
1865 return -EINVAL;
1866 }
1867
1868 map->name = strdup(map_name);
1869 if (!map->name) {
1870 pr_warn("failed to alloc map name\n");
1871 return -ENOMEM;
1872 }
1873 pr_debug("map %d is \"%s\"\n", i, map->name);
1874 def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
1875 /*
1876 * If the definition of the map in the object file fits in
1877 * bpf_map_def, copy it. Any extra fields in our version
1878 * of bpf_map_def will default to zero as a result of the
1879 * calloc above.
1880 */
1881 if (map_def_sz <= sizeof(struct bpf_map_def)) {
1882 memcpy(&map->def, def, map_def_sz);
1883 } else {
1884 /*
1885 * Here the map structure being read is bigger than what
1886 * we expect, truncate if the excess bits are all zero.
1887 * If they are not zero, reject this map as
1888 * incompatible.
1889 */
1890 char *b;
1891
1892 for (b = ((char *)def) + sizeof(struct bpf_map_def);
1893 b < ((char *)def) + map_def_sz; b++) {
1894 if (*b != 0) {
1895 pr_warn("maps section in %s: \"%s\" has unrecognized, non-zero options\n",
1896 obj->path, map_name);
1897 if (strict)
1898 return -EINVAL;
1899 }
1900 }
1901 memcpy(&map->def, def, sizeof(struct bpf_map_def));
1902 }
1903 }
1904 return 0;
1905 }
1906
1907 const struct btf_type *
skip_mods_and_typedefs(const struct btf * btf,__u32 id,__u32 * res_id)1908 skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
1909 {
1910 const struct btf_type *t = btf__type_by_id(btf, id);
1911
1912 if (res_id)
1913 *res_id = id;
1914
1915 while (btf_is_mod(t) || btf_is_typedef(t)) {
1916 if (res_id)
1917 *res_id = t->type;
1918 t = btf__type_by_id(btf, t->type);
1919 }
1920
1921 return t;
1922 }
1923
1924 static const struct btf_type *
resolve_func_ptr(const struct btf * btf,__u32 id,__u32 * res_id)1925 resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
1926 {
1927 const struct btf_type *t;
1928
1929 t = skip_mods_and_typedefs(btf, id, NULL);
1930 if (!btf_is_ptr(t))
1931 return NULL;
1932
1933 t = skip_mods_and_typedefs(btf, t->type, res_id);
1934
1935 return btf_is_func_proto(t) ? t : NULL;
1936 }
1937
__btf_kind_str(__u16 kind)1938 static const char *__btf_kind_str(__u16 kind)
1939 {
1940 switch (kind) {
1941 case BTF_KIND_UNKN: return "void";
1942 case BTF_KIND_INT: return "int";
1943 case BTF_KIND_PTR: return "ptr";
1944 case BTF_KIND_ARRAY: return "array";
1945 case BTF_KIND_STRUCT: return "struct";
1946 case BTF_KIND_UNION: return "union";
1947 case BTF_KIND_ENUM: return "enum";
1948 case BTF_KIND_FWD: return "fwd";
1949 case BTF_KIND_TYPEDEF: return "typedef";
1950 case BTF_KIND_VOLATILE: return "volatile";
1951 case BTF_KIND_CONST: return "const";
1952 case BTF_KIND_RESTRICT: return "restrict";
1953 case BTF_KIND_FUNC: return "func";
1954 case BTF_KIND_FUNC_PROTO: return "func_proto";
1955 case BTF_KIND_VAR: return "var";
1956 case BTF_KIND_DATASEC: return "datasec";
1957 case BTF_KIND_FLOAT: return "float";
1958 default: return "unknown";
1959 }
1960 }
1961
btf_kind_str(const struct btf_type * t)1962 const char *btf_kind_str(const struct btf_type *t)
1963 {
1964 return __btf_kind_str(btf_kind(t));
1965 }
1966
1967 /*
1968 * Fetch integer attribute of BTF map definition. Such attributes are
1969 * represented using a pointer to an array, in which dimensionality of array
1970 * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
1971 * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
1972 * type definition, while using only sizeof(void *) space in ELF data section.
1973 */
get_map_field_int(const char * map_name,const struct btf * btf,const struct btf_member * m,__u32 * res)1974 static bool get_map_field_int(const char *map_name, const struct btf *btf,
1975 const struct btf_member *m, __u32 *res)
1976 {
1977 const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
1978 const char *name = btf__name_by_offset(btf, m->name_off);
1979 const struct btf_array *arr_info;
1980 const struct btf_type *arr_t;
1981
1982 if (!btf_is_ptr(t)) {
1983 pr_warn("map '%s': attr '%s': expected PTR, got %s.\n",
1984 map_name, name, btf_kind_str(t));
1985 return false;
1986 }
1987
1988 arr_t = btf__type_by_id(btf, t->type);
1989 if (!arr_t) {
1990 pr_warn("map '%s': attr '%s': type [%u] not found.\n",
1991 map_name, name, t->type);
1992 return false;
1993 }
1994 if (!btf_is_array(arr_t)) {
1995 pr_warn("map '%s': attr '%s': expected ARRAY, got %s.\n",
1996 map_name, name, btf_kind_str(arr_t));
1997 return false;
1998 }
1999 arr_info = btf_array(arr_t);
2000 *res = arr_info->nelems;
2001 return true;
2002 }
2003
build_map_pin_path(struct bpf_map * map,const char * path)2004 static int build_map_pin_path(struct bpf_map *map, const char *path)
2005 {
2006 char buf[PATH_MAX];
2007 int len;
2008
2009 if (!path)
2010 path = "/sys/fs/bpf";
2011
2012 len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
2013 if (len < 0)
2014 return -EINVAL;
2015 else if (len >= PATH_MAX)
2016 return -ENAMETOOLONG;
2017
2018 return bpf_map__set_pin_path(map, buf);
2019 }
2020
parse_btf_map_def(const char * map_name,struct btf * btf,const struct btf_type * def_t,bool strict,struct btf_map_def * map_def,struct btf_map_def * inner_def)2021 int parse_btf_map_def(const char *map_name, struct btf *btf,
2022 const struct btf_type *def_t, bool strict,
2023 struct btf_map_def *map_def, struct btf_map_def *inner_def)
2024 {
2025 const struct btf_type *t;
2026 const struct btf_member *m;
2027 bool is_inner = inner_def == NULL;
2028 int vlen, i;
2029
2030 vlen = btf_vlen(def_t);
2031 m = btf_members(def_t);
2032 for (i = 0; i < vlen; i++, m++) {
2033 const char *name = btf__name_by_offset(btf, m->name_off);
2034
2035 if (!name) {
2036 pr_warn("map '%s': invalid field #%d.\n", map_name, i);
2037 return -EINVAL;
2038 }
2039 if (strcmp(name, "type") == 0) {
2040 if (!get_map_field_int(map_name, btf, m, &map_def->map_type))
2041 return -EINVAL;
2042 map_def->parts |= MAP_DEF_MAP_TYPE;
2043 } else if (strcmp(name, "max_entries") == 0) {
2044 if (!get_map_field_int(map_name, btf, m, &map_def->max_entries))
2045 return -EINVAL;
2046 map_def->parts |= MAP_DEF_MAX_ENTRIES;
2047 } else if (strcmp(name, "map_flags") == 0) {
2048 if (!get_map_field_int(map_name, btf, m, &map_def->map_flags))
2049 return -EINVAL;
2050 map_def->parts |= MAP_DEF_MAP_FLAGS;
2051 } else if (strcmp(name, "numa_node") == 0) {
2052 if (!get_map_field_int(map_name, btf, m, &map_def->numa_node))
2053 return -EINVAL;
2054 map_def->parts |= MAP_DEF_NUMA_NODE;
2055 } else if (strcmp(name, "key_size") == 0) {
2056 __u32 sz;
2057
2058 if (!get_map_field_int(map_name, btf, m, &sz))
2059 return -EINVAL;
2060 if (map_def->key_size && map_def->key_size != sz) {
2061 pr_warn("map '%s': conflicting key size %u != %u.\n",
2062 map_name, map_def->key_size, sz);
2063 return -EINVAL;
2064 }
2065 map_def->key_size = sz;
2066 map_def->parts |= MAP_DEF_KEY_SIZE;
2067 } else if (strcmp(name, "key") == 0) {
2068 __s64 sz;
2069
2070 t = btf__type_by_id(btf, m->type);
2071 if (!t) {
2072 pr_warn("map '%s': key type [%d] not found.\n",
2073 map_name, m->type);
2074 return -EINVAL;
2075 }
2076 if (!btf_is_ptr(t)) {
2077 pr_warn("map '%s': key spec is not PTR: %s.\n",
2078 map_name, btf_kind_str(t));
2079 return -EINVAL;
2080 }
2081 sz = btf__resolve_size(btf, t->type);
2082 if (sz < 0) {
2083 pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
2084 map_name, t->type, (ssize_t)sz);
2085 return sz;
2086 }
2087 if (map_def->key_size && map_def->key_size != sz) {
2088 pr_warn("map '%s': conflicting key size %u != %zd.\n",
2089 map_name, map_def->key_size, (ssize_t)sz);
2090 return -EINVAL;
2091 }
2092 map_def->key_size = sz;
2093 map_def->key_type_id = t->type;
2094 map_def->parts |= MAP_DEF_KEY_SIZE | MAP_DEF_KEY_TYPE;
2095 } else if (strcmp(name, "value_size") == 0) {
2096 __u32 sz;
2097
2098 if (!get_map_field_int(map_name, btf, m, &sz))
2099 return -EINVAL;
2100 if (map_def->value_size && map_def->value_size != sz) {
2101 pr_warn("map '%s': conflicting value size %u != %u.\n",
2102 map_name, map_def->value_size, sz);
2103 return -EINVAL;
2104 }
2105 map_def->value_size = sz;
2106 map_def->parts |= MAP_DEF_VALUE_SIZE;
2107 } else if (strcmp(name, "value") == 0) {
2108 __s64 sz;
2109
2110 t = btf__type_by_id(btf, m->type);
2111 if (!t) {
2112 pr_warn("map '%s': value type [%d] not found.\n",
2113 map_name, m->type);
2114 return -EINVAL;
2115 }
2116 if (!btf_is_ptr(t)) {
2117 pr_warn("map '%s': value spec is not PTR: %s.\n",
2118 map_name, btf_kind_str(t));
2119 return -EINVAL;
2120 }
2121 sz = btf__resolve_size(btf, t->type);
2122 if (sz < 0) {
2123 pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
2124 map_name, t->type, (ssize_t)sz);
2125 return sz;
2126 }
2127 if (map_def->value_size && map_def->value_size != sz) {
2128 pr_warn("map '%s': conflicting value size %u != %zd.\n",
2129 map_name, map_def->value_size, (ssize_t)sz);
2130 return -EINVAL;
2131 }
2132 map_def->value_size = sz;
2133 map_def->value_type_id = t->type;
2134 map_def->parts |= MAP_DEF_VALUE_SIZE | MAP_DEF_VALUE_TYPE;
2135 }
2136 else if (strcmp(name, "values") == 0) {
2137 char inner_map_name[128];
2138 int err;
2139
2140 if (is_inner) {
2141 pr_warn("map '%s': multi-level inner maps not supported.\n",
2142 map_name);
2143 return -ENOTSUP;
2144 }
2145 if (i != vlen - 1) {
2146 pr_warn("map '%s': '%s' member should be last.\n",
2147 map_name, name);
2148 return -EINVAL;
2149 }
2150 if (!bpf_map_type__is_map_in_map(map_def->map_type)) {
2151 pr_warn("map '%s': should be map-in-map.\n",
2152 map_name);
2153 return -ENOTSUP;
2154 }
2155 if (map_def->value_size && map_def->value_size != 4) {
2156 pr_warn("map '%s': conflicting value size %u != 4.\n",
2157 map_name, map_def->value_size);
2158 return -EINVAL;
2159 }
2160 map_def->value_size = 4;
2161 t = btf__type_by_id(btf, m->type);
2162 if (!t) {
2163 pr_warn("map '%s': map-in-map inner type [%d] not found.\n",
2164 map_name, m->type);
2165 return -EINVAL;
2166 }
2167 if (!btf_is_array(t) || btf_array(t)->nelems) {
2168 pr_warn("map '%s': map-in-map inner spec is not a zero-sized array.\n",
2169 map_name);
2170 return -EINVAL;
2171 }
2172 t = skip_mods_and_typedefs(btf, btf_array(t)->type, NULL);
2173 if (!btf_is_ptr(t)) {
2174 pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
2175 map_name, btf_kind_str(t));
2176 return -EINVAL;
2177 }
2178 t = skip_mods_and_typedefs(btf, t->type, NULL);
2179 if (!btf_is_struct(t)) {
2180 pr_warn("map '%s': map-in-map inner def is of unexpected kind %s.\n",
2181 map_name, btf_kind_str(t));
2182 return -EINVAL;
2183 }
2184
2185 snprintf(inner_map_name, sizeof(inner_map_name), "%s.inner", map_name);
2186 err = parse_btf_map_def(inner_map_name, btf, t, strict, inner_def, NULL);
2187 if (err)
2188 return err;
2189
2190 map_def->parts |= MAP_DEF_INNER_MAP;
2191 } else if (strcmp(name, "pinning") == 0) {
2192 __u32 val;
2193
2194 if (is_inner) {
2195 pr_warn("map '%s': inner def can't be pinned.\n", map_name);
2196 return -EINVAL;
2197 }
2198 if (!get_map_field_int(map_name, btf, m, &val))
2199 return -EINVAL;
2200 if (val != LIBBPF_PIN_NONE && val != LIBBPF_PIN_BY_NAME) {
2201 pr_warn("map '%s': invalid pinning value %u.\n",
2202 map_name, val);
2203 return -EINVAL;
2204 }
2205 map_def->pinning = val;
2206 map_def->parts |= MAP_DEF_PINNING;
2207 } else {
2208 if (strict) {
2209 pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
2210 return -ENOTSUP;
2211 }
2212 pr_debug("map '%s': ignoring unknown field '%s'.\n", map_name, name);
2213 }
2214 }
2215
2216 if (map_def->map_type == BPF_MAP_TYPE_UNSPEC) {
2217 pr_warn("map '%s': map type isn't specified.\n", map_name);
2218 return -EINVAL;
2219 }
2220
2221 return 0;
2222 }
2223
fill_map_from_def(struct bpf_map * map,const struct btf_map_def * def)2224 static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def)
2225 {
2226 map->def.type = def->map_type;
2227 map->def.key_size = def->key_size;
2228 map->def.value_size = def->value_size;
2229 map->def.max_entries = def->max_entries;
2230 map->def.map_flags = def->map_flags;
2231
2232 map->numa_node = def->numa_node;
2233 map->btf_key_type_id = def->key_type_id;
2234 map->btf_value_type_id = def->value_type_id;
2235
2236 if (def->parts & MAP_DEF_MAP_TYPE)
2237 pr_debug("map '%s': found type = %u.\n", map->name, def->map_type);
2238
2239 if (def->parts & MAP_DEF_KEY_TYPE)
2240 pr_debug("map '%s': found key [%u], sz = %u.\n",
2241 map->name, def->key_type_id, def->key_size);
2242 else if (def->parts & MAP_DEF_KEY_SIZE)
2243 pr_debug("map '%s': found key_size = %u.\n", map->name, def->key_size);
2244
2245 if (def->parts & MAP_DEF_VALUE_TYPE)
2246 pr_debug("map '%s': found value [%u], sz = %u.\n",
2247 map->name, def->value_type_id, def->value_size);
2248 else if (def->parts & MAP_DEF_VALUE_SIZE)
2249 pr_debug("map '%s': found value_size = %u.\n", map->name, def->value_size);
2250
2251 if (def->parts & MAP_DEF_MAX_ENTRIES)
2252 pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
2253 if (def->parts & MAP_DEF_MAP_FLAGS)
2254 pr_debug("map '%s': found map_flags = %u.\n", map->name, def->map_flags);
2255 if (def->parts & MAP_DEF_PINNING)
2256 pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
2257 if (def->parts & MAP_DEF_NUMA_NODE)
2258 pr_debug("map '%s': found numa_node = %u.\n", map->name, def->numa_node);
2259
2260 if (def->parts & MAP_DEF_INNER_MAP)
2261 pr_debug("map '%s': found inner map definition.\n", map->name);
2262 }
2263
bpf_object__init_user_btf_map(struct bpf_object * obj,const struct btf_type * sec,int var_idx,int sec_idx,const Elf_Data * data,bool strict,const char * pin_root_path)2264 static int bpf_object__init_user_btf_map(struct bpf_object *obj,
2265 const struct btf_type *sec,
2266 int var_idx, int sec_idx,
2267 const Elf_Data *data, bool strict,
2268 const char *pin_root_path)
2269 {
2270 struct btf_map_def map_def = {}, inner_def = {};
2271 const struct btf_type *var, *def;
2272 const struct btf_var_secinfo *vi;
2273 const struct btf_var *var_extra;
2274 const char *map_name;
2275 struct bpf_map *map;
2276 int err;
2277
2278 vi = btf_var_secinfos(sec) + var_idx;
2279 var = btf__type_by_id(obj->btf, vi->type);
2280 var_extra = btf_var(var);
2281 map_name = btf__name_by_offset(obj->btf, var->name_off);
2282
2283 if (map_name == NULL || map_name[0] == '\0') {
2284 pr_warn("map #%d: empty name.\n", var_idx);
2285 return -EINVAL;
2286 }
2287 if ((__u64)vi->offset + vi->size > data->d_size) {
2288 pr_warn("map '%s' BTF data is corrupted.\n", map_name);
2289 return -EINVAL;
2290 }
2291 if (!btf_is_var(var)) {
2292 pr_warn("map '%s': unexpected var kind %s.\n",
2293 map_name, btf_kind_str(var));
2294 return -EINVAL;
2295 }
2296 if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
2297 var_extra->linkage != BTF_VAR_STATIC) {
2298 pr_warn("map '%s': unsupported var linkage %u.\n",
2299 map_name, var_extra->linkage);
2300 return -EOPNOTSUPP;
2301 }
2302
2303 def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
2304 if (!btf_is_struct(def)) {
2305 pr_warn("map '%s': unexpected def kind %s.\n",
2306 map_name, btf_kind_str(var));
2307 return -EINVAL;
2308 }
2309 if (def->size > vi->size) {
2310 pr_warn("map '%s': invalid def size.\n", map_name);
2311 return -EINVAL;
2312 }
2313
2314 map = bpf_object__add_map(obj);
2315 if (IS_ERR(map))
2316 return PTR_ERR(map);
2317 map->name = strdup(map_name);
2318 if (!map->name) {
2319 pr_warn("map '%s': failed to alloc map name.\n", map_name);
2320 return -ENOMEM;
2321 }
2322 map->libbpf_type = LIBBPF_MAP_UNSPEC;
2323 map->def.type = BPF_MAP_TYPE_UNSPEC;
2324 map->sec_idx = sec_idx;
2325 map->sec_offset = vi->offset;
2326 map->btf_var_idx = var_idx;
2327 pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
2328 map_name, map->sec_idx, map->sec_offset);
2329
2330 err = parse_btf_map_def(map->name, obj->btf, def, strict, &map_def, &inner_def);
2331 if (err)
2332 return err;
2333
2334 fill_map_from_def(map, &map_def);
2335
2336 if (map_def.pinning == LIBBPF_PIN_BY_NAME) {
2337 err = build_map_pin_path(map, pin_root_path);
2338 if (err) {
2339 pr_warn("map '%s': couldn't build pin path.\n", map->name);
2340 return err;
2341 }
2342 }
2343
2344 if (map_def.parts & MAP_DEF_INNER_MAP) {
2345 map->inner_map = calloc(1, sizeof(*map->inner_map));
2346 if (!map->inner_map)
2347 return -ENOMEM;
2348 map->inner_map->fd = -1;
2349 map->inner_map->sec_idx = sec_idx;
2350 map->inner_map->name = malloc(strlen(map_name) + sizeof(".inner") + 1);
2351 if (!map->inner_map->name)
2352 return -ENOMEM;
2353 sprintf(map->inner_map->name, "%s.inner", map_name);
2354
2355 fill_map_from_def(map->inner_map, &inner_def);
2356 }
2357
2358 return 0;
2359 }
2360
bpf_object__init_user_btf_maps(struct bpf_object * obj,bool strict,const char * pin_root_path)2361 static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
2362 const char *pin_root_path)
2363 {
2364 const struct btf_type *sec = NULL;
2365 int nr_types, i, vlen, err;
2366 const struct btf_type *t;
2367 const char *name;
2368 Elf_Data *data;
2369 Elf_Scn *scn;
2370
2371 if (obj->efile.btf_maps_shndx < 0)
2372 return 0;
2373
2374 scn = elf_sec_by_idx(obj, obj->efile.btf_maps_shndx);
2375 data = elf_sec_data(obj, scn);
2376 if (!scn || !data) {
2377 pr_warn("elf: failed to get %s map definitions for %s\n",
2378 MAPS_ELF_SEC, obj->path);
2379 return -EINVAL;
2380 }
2381
2382 nr_types = btf__get_nr_types(obj->btf);
2383 for (i = 1; i <= nr_types; i++) {
2384 t = btf__type_by_id(obj->btf, i);
2385 if (!btf_is_datasec(t))
2386 continue;
2387 name = btf__name_by_offset(obj->btf, t->name_off);
2388 if (strcmp(name, MAPS_ELF_SEC) == 0) {
2389 sec = t;
2390 obj->efile.btf_maps_sec_btf_id = i;
2391 break;
2392 }
2393 }
2394
2395 if (!sec) {
2396 pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
2397 return -ENOENT;
2398 }
2399
2400 vlen = btf_vlen(sec);
2401 for (i = 0; i < vlen; i++) {
2402 err = bpf_object__init_user_btf_map(obj, sec, i,
2403 obj->efile.btf_maps_shndx,
2404 data, strict,
2405 pin_root_path);
2406 if (err)
2407 return err;
2408 }
2409
2410 return 0;
2411 }
2412
bpf_object__init_maps(struct bpf_object * obj,const struct bpf_object_open_opts * opts)2413 static int bpf_object__init_maps(struct bpf_object *obj,
2414 const struct bpf_object_open_opts *opts)
2415 {
2416 const char *pin_root_path;
2417 bool strict;
2418 int err;
2419
2420 strict = !OPTS_GET(opts, relaxed_maps, false);
2421 pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
2422
2423 err = bpf_object__init_user_maps(obj, strict);
2424 err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
2425 err = err ?: bpf_object__init_global_data_maps(obj);
2426 err = err ?: bpf_object__init_kconfig_map(obj);
2427 err = err ?: bpf_object__init_struct_ops_maps(obj);
2428 if (err)
2429 return err;
2430
2431 return 0;
2432 }
2433
section_have_execinstr(struct bpf_object * obj,int idx)2434 static bool section_have_execinstr(struct bpf_object *obj, int idx)
2435 {
2436 GElf_Shdr sh;
2437
2438 if (elf_sec_hdr(obj, elf_sec_by_idx(obj, idx), &sh))
2439 return false;
2440
2441 return sh.sh_flags & SHF_EXECINSTR;
2442 }
2443
btf_needs_sanitization(struct bpf_object * obj)2444 static bool btf_needs_sanitization(struct bpf_object *obj)
2445 {
2446 bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
2447 bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
2448 bool has_float = kernel_supports(FEAT_BTF_FLOAT);
2449 bool has_func = kernel_supports(FEAT_BTF_FUNC);
2450
2451 return !has_func || !has_datasec || !has_func_global || !has_float;
2452 }
2453
bpf_object__sanitize_btf(struct bpf_object * obj,struct btf * btf)2454 static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
2455 {
2456 bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
2457 bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
2458 bool has_float = kernel_supports(FEAT_BTF_FLOAT);
2459 bool has_func = kernel_supports(FEAT_BTF_FUNC);
2460 struct btf_type *t;
2461 int i, j, vlen;
2462
2463 for (i = 1; i <= btf__get_nr_types(btf); i++) {
2464 t = (struct btf_type *)btf__type_by_id(btf, i);
2465
2466 if (!has_datasec && btf_is_var(t)) {
2467 /* replace VAR with INT */
2468 t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
2469 /*
2470 * using size = 1 is the safest choice, 4 will be too
2471 * big and cause kernel BTF validation failure if
2472 * original variable took less than 4 bytes
2473 */
2474 t->size = 1;
2475 *(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
2476 } else if (!has_datasec && btf_is_datasec(t)) {
2477 /* replace DATASEC with STRUCT */
2478 const struct btf_var_secinfo *v = btf_var_secinfos(t);
2479 struct btf_member *m = btf_members(t);
2480 struct btf_type *vt;
2481 char *name;
2482
2483 name = (char *)btf__name_by_offset(btf, t->name_off);
2484 while (*name) {
2485 if (*name == '.')
2486 *name = '_';
2487 name++;
2488 }
2489
2490 vlen = btf_vlen(t);
2491 t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
2492 for (j = 0; j < vlen; j++, v++, m++) {
2493 /* order of field assignments is important */
2494 m->offset = v->offset * 8;
2495 m->type = v->type;
2496 /* preserve variable name as member name */
2497 vt = (void *)btf__type_by_id(btf, v->type);
2498 m->name_off = vt->name_off;
2499 }
2500 } else if (!has_func && btf_is_func_proto(t)) {
2501 /* replace FUNC_PROTO with ENUM */
2502 vlen = btf_vlen(t);
2503 t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
2504 t->size = sizeof(__u32); /* kernel enforced */
2505 } else if (!has_func && btf_is_func(t)) {
2506 /* replace FUNC with TYPEDEF */
2507 t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
2508 } else if (!has_func_global && btf_is_func(t)) {
2509 /* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
2510 t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
2511 } else if (!has_float && btf_is_float(t)) {
2512 /* replace FLOAT with an equally-sized empty STRUCT;
2513 * since C compilers do not accept e.g. "float" as a
2514 * valid struct name, make it anonymous
2515 */
2516 t->name_off = 0;
2517 t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);
2518 }
2519 }
2520 }
2521
libbpf_needs_btf(const struct bpf_object * obj)2522 static bool libbpf_needs_btf(const struct bpf_object *obj)
2523 {
2524 return obj->efile.btf_maps_shndx >= 0 ||
2525 obj->efile.st_ops_shndx >= 0 ||
2526 obj->nr_extern > 0;
2527 }
2528
kernel_needs_btf(const struct bpf_object * obj)2529 static bool kernel_needs_btf(const struct bpf_object *obj)
2530 {
2531 return obj->efile.st_ops_shndx >= 0;
2532 }
2533
bpf_object__init_btf(struct bpf_object * obj,Elf_Data * btf_data,Elf_Data * btf_ext_data)2534 static int bpf_object__init_btf(struct bpf_object *obj,
2535 Elf_Data *btf_data,
2536 Elf_Data *btf_ext_data)
2537 {
2538 int err = -ENOENT;
2539
2540 if (btf_data) {
2541 obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
2542 if (IS_ERR(obj->btf)) {
2543 err = PTR_ERR(obj->btf);
2544 obj->btf = NULL;
2545 pr_warn("Error loading ELF section %s: %d.\n",
2546 BTF_ELF_SEC, err);
2547 goto out;
2548 }
2549 /* enforce 8-byte pointers for BPF-targeted BTFs */
2550 btf__set_pointer_size(obj->btf, 8);
2551 err = 0;
2552 }
2553 if (btf_ext_data) {
2554 if (!obj->btf) {
2555 pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
2556 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
2557 goto out;
2558 }
2559 obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
2560 btf_ext_data->d_size);
2561 if (IS_ERR(obj->btf_ext)) {
2562 pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n",
2563 BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
2564 obj->btf_ext = NULL;
2565 goto out;
2566 }
2567 }
2568 out:
2569 if (err && libbpf_needs_btf(obj)) {
2570 pr_warn("BTF is required, but is missing or corrupted.\n");
2571 return err;
2572 }
2573 return 0;
2574 }
2575
bpf_object__finalize_btf(struct bpf_object * obj)2576 static int bpf_object__finalize_btf(struct bpf_object *obj)
2577 {
2578 int err;
2579
2580 if (!obj->btf)
2581 return 0;
2582
2583 err = btf__finalize_data(obj, obj->btf);
2584 if (err) {
2585 pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
2586 return err;
2587 }
2588
2589 return 0;
2590 }
2591
prog_needs_vmlinux_btf(struct bpf_program * prog)2592 static bool prog_needs_vmlinux_btf(struct bpf_program *prog)
2593 {
2594 if (prog->type == BPF_PROG_TYPE_STRUCT_OPS ||
2595 prog->type == BPF_PROG_TYPE_LSM)
2596 return true;
2597
2598 /* BPF_PROG_TYPE_TRACING programs which do not attach to other programs
2599 * also need vmlinux BTF
2600 */
2601 if (prog->type == BPF_PROG_TYPE_TRACING && !prog->attach_prog_fd)
2602 return true;
2603
2604 return false;
2605 }
2606
obj_needs_vmlinux_btf(const struct bpf_object * obj)2607 static bool obj_needs_vmlinux_btf(const struct bpf_object *obj)
2608 {
2609 struct bpf_program *prog;
2610 int i;
2611
2612 /* CO-RE relocations need kernel BTF */
2613 if (obj->btf_ext && obj->btf_ext->core_relo_info.len)
2614 return true;
2615
2616 /* Support for typed ksyms needs kernel BTF */
2617 for (i = 0; i < obj->nr_extern; i++) {
2618 const struct extern_desc *ext;
2619
2620 ext = &obj->externs[i];
2621 if (ext->type == EXT_KSYM && ext->ksym.type_id)
2622 return true;
2623 }
2624
2625 bpf_object__for_each_program(prog, obj) {
2626 if (!prog->load)
2627 continue;
2628 if (prog_needs_vmlinux_btf(prog))
2629 return true;
2630 }
2631
2632 return false;
2633 }
2634
bpf_object__load_vmlinux_btf(struct bpf_object * obj,bool force)2635 static int bpf_object__load_vmlinux_btf(struct bpf_object *obj, bool force)
2636 {
2637 int err;
2638
2639 /* btf_vmlinux could be loaded earlier */
2640 if (obj->btf_vmlinux)
2641 return 0;
2642
2643 if (!force && !obj_needs_vmlinux_btf(obj))
2644 return 0;
2645
2646 obj->btf_vmlinux = libbpf_find_kernel_btf();
2647 if (IS_ERR(obj->btf_vmlinux)) {
2648 err = PTR_ERR(obj->btf_vmlinux);
2649 pr_warn("Error loading vmlinux BTF: %d\n", err);
2650 obj->btf_vmlinux = NULL;
2651 return err;
2652 }
2653 return 0;
2654 }
2655
bpf_object__sanitize_and_load_btf(struct bpf_object * obj)2656 static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
2657 {
2658 struct btf *kern_btf = obj->btf;
2659 bool btf_mandatory, sanitize;
2660 int i, err = 0;
2661
2662 if (!obj->btf)
2663 return 0;
2664
2665 if (!kernel_supports(FEAT_BTF)) {
2666 if (kernel_needs_btf(obj)) {
2667 err = -EOPNOTSUPP;
2668 goto report;
2669 }
2670 pr_debug("Kernel doesn't support BTF, skipping uploading it.\n");
2671 return 0;
2672 }
2673
2674 /* Even though some subprogs are global/weak, user might prefer more
2675 * permissive BPF verification process that BPF verifier performs for
2676 * static functions, taking into account more context from the caller
2677 * functions. In such case, they need to mark such subprogs with
2678 * __attribute__((visibility("hidden"))) and libbpf will adjust
2679 * corresponding FUNC BTF type to be marked as static and trigger more
2680 * involved BPF verification process.
2681 */
2682 for (i = 0; i < obj->nr_programs; i++) {
2683 struct bpf_program *prog = &obj->programs[i];
2684 struct btf_type *t;
2685 const char *name;
2686 int j, n;
2687
2688 if (!prog->mark_btf_static || !prog_is_subprog(obj, prog))
2689 continue;
2690
2691 n = btf__get_nr_types(obj->btf);
2692 for (j = 1; j <= n; j++) {
2693 t = btf_type_by_id(obj->btf, j);
2694 if (!btf_is_func(t) || btf_func_linkage(t) != BTF_FUNC_GLOBAL)
2695 continue;
2696
2697 name = btf__str_by_offset(obj->btf, t->name_off);
2698 if (strcmp(name, prog->name) != 0)
2699 continue;
2700
2701 t->info = btf_type_info(BTF_KIND_FUNC, BTF_FUNC_STATIC, 0);
2702 break;
2703 }
2704 }
2705
2706 sanitize = btf_needs_sanitization(obj);
2707 if (sanitize) {
2708 const void *raw_data;
2709 __u32 sz;
2710
2711 /* clone BTF to sanitize a copy and leave the original intact */
2712 raw_data = btf__get_raw_data(obj->btf, &sz);
2713 kern_btf = btf__new(raw_data, sz);
2714 if (IS_ERR(kern_btf))
2715 return PTR_ERR(kern_btf);
2716
2717 /* enforce 8-byte pointers for BPF-targeted BTFs */
2718 btf__set_pointer_size(obj->btf, 8);
2719 bpf_object__sanitize_btf(obj, kern_btf);
2720 }
2721
2722 err = btf__load(kern_btf);
2723 if (sanitize) {
2724 if (!err) {
2725 /* move fd to libbpf's BTF */
2726 btf__set_fd(obj->btf, btf__fd(kern_btf));
2727 btf__set_fd(kern_btf, -1);
2728 }
2729 btf__free(kern_btf);
2730 }
2731 report:
2732 if (err) {
2733 btf_mandatory = kernel_needs_btf(obj);
2734 pr_warn("Error loading .BTF into kernel: %d. %s\n", err,
2735 btf_mandatory ? "BTF is mandatory, can't proceed."
2736 : "BTF is optional, ignoring.");
2737 if (!btf_mandatory)
2738 err = 0;
2739 }
2740 return err;
2741 }
2742
elf_sym_str(const struct bpf_object * obj,size_t off)2743 static const char *elf_sym_str(const struct bpf_object *obj, size_t off)
2744 {
2745 const char *name;
2746
2747 name = elf_strptr(obj->efile.elf, obj->efile.strtabidx, off);
2748 if (!name) {
2749 pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
2750 off, obj->path, elf_errmsg(-1));
2751 return NULL;
2752 }
2753
2754 return name;
2755 }
2756
elf_sec_str(const struct bpf_object * obj,size_t off)2757 static const char *elf_sec_str(const struct bpf_object *obj, size_t off)
2758 {
2759 const char *name;
2760
2761 name = elf_strptr(obj->efile.elf, obj->efile.shstrndx, off);
2762 if (!name) {
2763 pr_warn("elf: failed to get section name string at offset %zu from %s: %s\n",
2764 off, obj->path, elf_errmsg(-1));
2765 return NULL;
2766 }
2767
2768 return name;
2769 }
2770
elf_sec_by_idx(const struct bpf_object * obj,size_t idx)2771 static Elf_Scn *elf_sec_by_idx(const struct bpf_object *obj, size_t idx)
2772 {
2773 Elf_Scn *scn;
2774
2775 scn = elf_getscn(obj->efile.elf, idx);
2776 if (!scn) {
2777 pr_warn("elf: failed to get section(%zu) from %s: %s\n",
2778 idx, obj->path, elf_errmsg(-1));
2779 return NULL;
2780 }
2781 return scn;
2782 }
2783
elf_sec_by_name(const struct bpf_object * obj,const char * name)2784 static Elf_Scn *elf_sec_by_name(const struct bpf_object *obj, const char *name)
2785 {
2786 Elf_Scn *scn = NULL;
2787 Elf *elf = obj->efile.elf;
2788 const char *sec_name;
2789
2790 while ((scn = elf_nextscn(elf, scn)) != NULL) {
2791 sec_name = elf_sec_name(obj, scn);
2792 if (!sec_name)
2793 return NULL;
2794
2795 if (strcmp(sec_name, name) != 0)
2796 continue;
2797
2798 return scn;
2799 }
2800 return NULL;
2801 }
2802
elf_sec_hdr(const struct bpf_object * obj,Elf_Scn * scn,GElf_Shdr * hdr)2803 static int elf_sec_hdr(const struct bpf_object *obj, Elf_Scn *scn, GElf_Shdr *hdr)
2804 {
2805 if (!scn)
2806 return -EINVAL;
2807
2808 if (gelf_getshdr(scn, hdr) != hdr) {
2809 pr_warn("elf: failed to get section(%zu) header from %s: %s\n",
2810 elf_ndxscn(scn), obj->path, elf_errmsg(-1));
2811 return -EINVAL;
2812 }
2813
2814 return 0;
2815 }
2816
elf_sec_name(const struct bpf_object * obj,Elf_Scn * scn)2817 static const char *elf_sec_name(const struct bpf_object *obj, Elf_Scn *scn)
2818 {
2819 const char *name;
2820 GElf_Shdr sh;
2821
2822 if (!scn)
2823 return NULL;
2824
2825 if (elf_sec_hdr(obj, scn, &sh))
2826 return NULL;
2827
2828 name = elf_sec_str(obj, sh.sh_name);
2829 if (!name) {
2830 pr_warn("elf: failed to get section(%zu) name from %s: %s\n",
2831 elf_ndxscn(scn), obj->path, elf_errmsg(-1));
2832 return NULL;
2833 }
2834
2835 return name;
2836 }
2837
elf_sec_data(const struct bpf_object * obj,Elf_Scn * scn)2838 static Elf_Data *elf_sec_data(const struct bpf_object *obj, Elf_Scn *scn)
2839 {
2840 Elf_Data *data;
2841
2842 if (!scn)
2843 return NULL;
2844
2845 data = elf_getdata(scn, 0);
2846 if (!data) {
2847 pr_warn("elf: failed to get section(%zu) %s data from %s: %s\n",
2848 elf_ndxscn(scn), elf_sec_name(obj, scn) ?: "<?>",
2849 obj->path, elf_errmsg(-1));
2850 return NULL;
2851 }
2852
2853 return data;
2854 }
2855
is_sec_name_dwarf(const char * name)2856 static bool is_sec_name_dwarf(const char *name)
2857 {
2858 /* approximation, but the actual list is too long */
2859 return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0;
2860 }
2861
ignore_elf_section(GElf_Shdr * hdr,const char * name)2862 static bool ignore_elf_section(GElf_Shdr *hdr, const char *name)
2863 {
2864 /* no special handling of .strtab */
2865 if (hdr->sh_type == SHT_STRTAB)
2866 return true;
2867
2868 /* ignore .llvm_addrsig section as well */
2869 if (hdr->sh_type == SHT_LLVM_ADDRSIG)
2870 return true;
2871
2872 /* no subprograms will lead to an empty .text section, ignore it */
2873 if (hdr->sh_type == SHT_PROGBITS && hdr->sh_size == 0 &&
2874 strcmp(name, ".text") == 0)
2875 return true;
2876
2877 /* DWARF sections */
2878 if (is_sec_name_dwarf(name))
2879 return true;
2880
2881 if (strncmp(name, ".rel", sizeof(".rel") - 1) == 0) {
2882 name += sizeof(".rel") - 1;
2883 /* DWARF section relocations */
2884 if (is_sec_name_dwarf(name))
2885 return true;
2886
2887 /* .BTF and .BTF.ext don't need relocations */
2888 if (strcmp(name, BTF_ELF_SEC) == 0 ||
2889 strcmp(name, BTF_EXT_ELF_SEC) == 0)
2890 return true;
2891 }
2892
2893 return false;
2894 }
2895
cmp_progs(const void * _a,const void * _b)2896 static int cmp_progs(const void *_a, const void *_b)
2897 {
2898 const struct bpf_program *a = _a;
2899 const struct bpf_program *b = _b;
2900
2901 if (a->sec_idx != b->sec_idx)
2902 return a->sec_idx < b->sec_idx ? -1 : 1;
2903
2904 /* sec_insn_off can't be the same within the section */
2905 return a->sec_insn_off < b->sec_insn_off ? -1 : 1;
2906 }
2907
bpf_object__elf_collect(struct bpf_object * obj)2908 static int bpf_object__elf_collect(struct bpf_object *obj)
2909 {
2910 Elf *elf = obj->efile.elf;
2911 Elf_Data *btf_ext_data = NULL;
2912 Elf_Data *btf_data = NULL;
2913 int idx = 0, err = 0;
2914 const char *name;
2915 Elf_Data *data;
2916 Elf_Scn *scn;
2917 GElf_Shdr sh;
2918
2919 /* a bunch of ELF parsing functionality depends on processing symbols,
2920 * so do the first pass and find the symbol table
2921 */
2922 scn = NULL;
2923 while ((scn = elf_nextscn(elf, scn)) != NULL) {
2924 if (elf_sec_hdr(obj, scn, &sh))
2925 return -LIBBPF_ERRNO__FORMAT;
2926
2927 if (sh.sh_type == SHT_SYMTAB) {
2928 if (obj->efile.symbols) {
2929 pr_warn("elf: multiple symbol tables in %s\n", obj->path);
2930 return -LIBBPF_ERRNO__FORMAT;
2931 }
2932
2933 data = elf_sec_data(obj, scn);
2934 if (!data)
2935 return -LIBBPF_ERRNO__FORMAT;
2936
2937 obj->efile.symbols = data;
2938 obj->efile.symbols_shndx = elf_ndxscn(scn);
2939 obj->efile.strtabidx = sh.sh_link;
2940 }
2941 }
2942
2943 scn = NULL;
2944 while ((scn = elf_nextscn(elf, scn)) != NULL) {
2945 idx++;
2946
2947 if (elf_sec_hdr(obj, scn, &sh))
2948 return -LIBBPF_ERRNO__FORMAT;
2949
2950 name = elf_sec_str(obj, sh.sh_name);
2951 if (!name)
2952 return -LIBBPF_ERRNO__FORMAT;
2953
2954 if (ignore_elf_section(&sh, name))
2955 continue;
2956
2957 data = elf_sec_data(obj, scn);
2958 if (!data)
2959 return -LIBBPF_ERRNO__FORMAT;
2960
2961 pr_debug("elf: section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
2962 idx, name, (unsigned long)data->d_size,
2963 (int)sh.sh_link, (unsigned long)sh.sh_flags,
2964 (int)sh.sh_type);
2965
2966 if (strcmp(name, "license") == 0) {
2967 err = bpf_object__init_license(obj, data->d_buf, data->d_size);
2968 if (err)
2969 return err;
2970 } else if (strcmp(name, "version") == 0) {
2971 err = bpf_object__init_kversion(obj, data->d_buf, data->d_size);
2972 if (err)
2973 return err;
2974 } else if (strcmp(name, "maps") == 0) {
2975 obj->efile.maps_shndx = idx;
2976 } else if (strcmp(name, MAPS_ELF_SEC) == 0) {
2977 obj->efile.btf_maps_shndx = idx;
2978 } else if (strcmp(name, BTF_ELF_SEC) == 0) {
2979 btf_data = data;
2980 } else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
2981 btf_ext_data = data;
2982 } else if (sh.sh_type == SHT_SYMTAB) {
2983 /* already processed during the first pass above */
2984 } else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
2985 if (sh.sh_flags & SHF_EXECINSTR) {
2986 if (strcmp(name, ".text") == 0)
2987 obj->efile.text_shndx = idx;
2988 err = bpf_object__add_programs(obj, data, name, idx);
2989 if (err)
2990 return err;
2991 } else if (strcmp(name, DATA_SEC) == 0) {
2992 obj->efile.data = data;
2993 obj->efile.data_shndx = idx;
2994 } else if (strcmp(name, RODATA_SEC) == 0) {
2995 obj->efile.rodata = data;
2996 obj->efile.rodata_shndx = idx;
2997 } else if (strcmp(name, STRUCT_OPS_SEC) == 0) {
2998 obj->efile.st_ops_data = data;
2999 obj->efile.st_ops_shndx = idx;
3000 } else {
3001 pr_info("elf: skipping unrecognized data section(%d) %s\n",
3002 idx, name);
3003 }
3004 } else if (sh.sh_type == SHT_REL) {
3005 int nr_sects = obj->efile.nr_reloc_sects;
3006 void *sects = obj->efile.reloc_sects;
3007 int sec = sh.sh_info; /* points to other section */
3008
3009 /* Only do relo for section with exec instructions */
3010 if (!section_have_execinstr(obj, sec) &&
3011 strcmp(name, ".rel" STRUCT_OPS_SEC) &&
3012 strcmp(name, ".rel" MAPS_ELF_SEC)) {
3013 pr_info("elf: skipping relo section(%d) %s for section(%d) %s\n",
3014 idx, name, sec,
3015 elf_sec_name(obj, elf_sec_by_idx(obj, sec)) ?: "<?>");
3016 continue;
3017 }
3018
3019 sects = libbpf_reallocarray(sects, nr_sects + 1,
3020 sizeof(*obj->efile.reloc_sects));
3021 if (!sects)
3022 return -ENOMEM;
3023
3024 obj->efile.reloc_sects = sects;
3025 obj->efile.nr_reloc_sects++;
3026
3027 obj->efile.reloc_sects[nr_sects].shdr = sh;
3028 obj->efile.reloc_sects[nr_sects].data = data;
3029 } else if (sh.sh_type == SHT_NOBITS && strcmp(name, BSS_SEC) == 0) {
3030 obj->efile.bss = data;
3031 obj->efile.bss_shndx = idx;
3032 } else {
3033 pr_info("elf: skipping section(%d) %s (size %zu)\n", idx, name,
3034 (size_t)sh.sh_size);
3035 }
3036 }
3037
3038 if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
3039 pr_warn("elf: symbol strings section missing or invalid in %s\n", obj->path);
3040 return -LIBBPF_ERRNO__FORMAT;
3041 }
3042
3043 /* sort BPF programs by section name and in-section instruction offset
3044 * for faster search */
3045 qsort(obj->programs, obj->nr_programs, sizeof(*obj->programs), cmp_progs);
3046
3047 return bpf_object__init_btf(obj, btf_data, btf_ext_data);
3048 }
3049
sym_is_extern(const GElf_Sym * sym)3050 static bool sym_is_extern(const GElf_Sym *sym)
3051 {
3052 int bind = GELF_ST_BIND(sym->st_info);
3053 /* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
3054 return sym->st_shndx == SHN_UNDEF &&
3055 (bind == STB_GLOBAL || bind == STB_WEAK) &&
3056 GELF_ST_TYPE(sym->st_info) == STT_NOTYPE;
3057 }
3058
sym_is_subprog(const GElf_Sym * sym,int text_shndx)3059 static bool sym_is_subprog(const GElf_Sym *sym, int text_shndx)
3060 {
3061 int bind = GELF_ST_BIND(sym->st_info);
3062 int type = GELF_ST_TYPE(sym->st_info);
3063
3064 /* in .text section */
3065 if (sym->st_shndx != text_shndx)
3066 return false;
3067
3068 /* local function */
3069 if (bind == STB_LOCAL && type == STT_SECTION)
3070 return true;
3071
3072 /* global function */
3073 return bind == STB_GLOBAL && type == STT_FUNC;
3074 }
3075
find_extern_btf_id(const struct btf * btf,const char * ext_name)3076 static int find_extern_btf_id(const struct btf *btf, const char *ext_name)
3077 {
3078 const struct btf_type *t;
3079 const char *tname;
3080 int i, n;
3081
3082 if (!btf)
3083 return -ESRCH;
3084
3085 n = btf__get_nr_types(btf);
3086 for (i = 1; i <= n; i++) {
3087 t = btf__type_by_id(btf, i);
3088
3089 if (!btf_is_var(t) && !btf_is_func(t))
3090 continue;
3091
3092 tname = btf__name_by_offset(btf, t->name_off);
3093 if (strcmp(tname, ext_name))
3094 continue;
3095
3096 if (btf_is_var(t) &&
3097 btf_var(t)->linkage != BTF_VAR_GLOBAL_EXTERN)
3098 return -EINVAL;
3099
3100 if (btf_is_func(t) && btf_func_linkage(t) != BTF_FUNC_EXTERN)
3101 return -EINVAL;
3102
3103 return i;
3104 }
3105
3106 return -ENOENT;
3107 }
3108
find_extern_sec_btf_id(struct btf * btf,int ext_btf_id)3109 static int find_extern_sec_btf_id(struct btf *btf, int ext_btf_id) {
3110 const struct btf_var_secinfo *vs;
3111 const struct btf_type *t;
3112 int i, j, n;
3113
3114 if (!btf)
3115 return -ESRCH;
3116
3117 n = btf__get_nr_types(btf);
3118 for (i = 1; i <= n; i++) {
3119 t = btf__type_by_id(btf, i);
3120
3121 if (!btf_is_datasec(t))
3122 continue;
3123
3124 vs = btf_var_secinfos(t);
3125 for (j = 0; j < btf_vlen(t); j++, vs++) {
3126 if (vs->type == ext_btf_id)
3127 return i;
3128 }
3129 }
3130
3131 return -ENOENT;
3132 }
3133
find_kcfg_type(const struct btf * btf,int id,bool * is_signed)3134 static enum kcfg_type find_kcfg_type(const struct btf *btf, int id,
3135 bool *is_signed)
3136 {
3137 const struct btf_type *t;
3138 const char *name;
3139
3140 t = skip_mods_and_typedefs(btf, id, NULL);
3141 name = btf__name_by_offset(btf, t->name_off);
3142
3143 if (is_signed)
3144 *is_signed = false;
3145 switch (btf_kind(t)) {
3146 case BTF_KIND_INT: {
3147 int enc = btf_int_encoding(t);
3148
3149 if (enc & BTF_INT_BOOL)
3150 return t->size == 1 ? KCFG_BOOL : KCFG_UNKNOWN;
3151 if (is_signed)
3152 *is_signed = enc & BTF_INT_SIGNED;
3153 if (t->size == 1)
3154 return KCFG_CHAR;
3155 if (t->size < 1 || t->size > 8 || (t->size & (t->size - 1)))
3156 return KCFG_UNKNOWN;
3157 return KCFG_INT;
3158 }
3159 case BTF_KIND_ENUM:
3160 if (t->size != 4)
3161 return KCFG_UNKNOWN;
3162 if (strcmp(name, "libbpf_tristate"))
3163 return KCFG_UNKNOWN;
3164 return KCFG_TRISTATE;
3165 case BTF_KIND_ARRAY:
3166 if (btf_array(t)->nelems == 0)
3167 return KCFG_UNKNOWN;
3168 if (find_kcfg_type(btf, btf_array(t)->type, NULL) != KCFG_CHAR)
3169 return KCFG_UNKNOWN;
3170 return KCFG_CHAR_ARR;
3171 default:
3172 return KCFG_UNKNOWN;
3173 }
3174 }
3175
cmp_externs(const void * _a,const void * _b)3176 static int cmp_externs(const void *_a, const void *_b)
3177 {
3178 const struct extern_desc *a = _a;
3179 const struct extern_desc *b = _b;
3180
3181 if (a->type != b->type)
3182 return a->type < b->type ? -1 : 1;
3183
3184 if (a->type == EXT_KCFG) {
3185 /* descending order by alignment requirements */
3186 if (a->kcfg.align != b->kcfg.align)
3187 return a->kcfg.align > b->kcfg.align ? -1 : 1;
3188 /* ascending order by size, within same alignment class */
3189 if (a->kcfg.sz != b->kcfg.sz)
3190 return a->kcfg.sz < b->kcfg.sz ? -1 : 1;
3191 }
3192
3193 /* resolve ties by name */
3194 return strcmp(a->name, b->name);
3195 }
3196
find_int_btf_id(const struct btf * btf)3197 static int find_int_btf_id(const struct btf *btf)
3198 {
3199 const struct btf_type *t;
3200 int i, n;
3201
3202 n = btf__get_nr_types(btf);
3203 for (i = 1; i <= n; i++) {
3204 t = btf__type_by_id(btf, i);
3205
3206 if (btf_is_int(t) && btf_int_bits(t) == 32)
3207 return i;
3208 }
3209
3210 return 0;
3211 }
3212
add_dummy_ksym_var(struct btf * btf)3213 static int add_dummy_ksym_var(struct btf *btf)
3214 {
3215 int i, int_btf_id, sec_btf_id, dummy_var_btf_id;
3216 const struct btf_var_secinfo *vs;
3217 const struct btf_type *sec;
3218
3219 sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
3220 BTF_KIND_DATASEC);
3221 if (sec_btf_id < 0)
3222 return 0;
3223
3224 sec = btf__type_by_id(btf, sec_btf_id);
3225 vs = btf_var_secinfos(sec);
3226 for (i = 0; i < btf_vlen(sec); i++, vs++) {
3227 const struct btf_type *vt;
3228
3229 vt = btf__type_by_id(btf, vs->type);
3230 if (btf_is_func(vt))
3231 break;
3232 }
3233
3234 /* No func in ksyms sec. No need to add dummy var. */
3235 if (i == btf_vlen(sec))
3236 return 0;
3237
3238 int_btf_id = find_int_btf_id(btf);
3239 dummy_var_btf_id = btf__add_var(btf,
3240 "dummy_ksym",
3241 BTF_VAR_GLOBAL_ALLOCATED,
3242 int_btf_id);
3243 if (dummy_var_btf_id < 0)
3244 pr_warn("cannot create a dummy_ksym var\n");
3245
3246 return dummy_var_btf_id;
3247 }
3248
bpf_object__collect_externs(struct bpf_object * obj)3249 static int bpf_object__collect_externs(struct bpf_object *obj)
3250 {
3251 struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
3252 const struct btf_type *t;
3253 struct extern_desc *ext;
3254 int i, n, off, dummy_var_btf_id;
3255 const char *ext_name, *sec_name;
3256 Elf_Scn *scn;
3257 GElf_Shdr sh;
3258
3259 if (!obj->efile.symbols)
3260 return 0;
3261
3262 scn = elf_sec_by_idx(obj, obj->efile.symbols_shndx);
3263 if (elf_sec_hdr(obj, scn, &sh))
3264 return -LIBBPF_ERRNO__FORMAT;
3265
3266 dummy_var_btf_id = add_dummy_ksym_var(obj->btf);
3267 if (dummy_var_btf_id < 0)
3268 return dummy_var_btf_id;
3269
3270 n = sh.sh_size / sh.sh_entsize;
3271 pr_debug("looking for externs among %d symbols...\n", n);
3272
3273 for (i = 0; i < n; i++) {
3274 GElf_Sym sym;
3275
3276 if (!gelf_getsym(obj->efile.symbols, i, &sym))
3277 return -LIBBPF_ERRNO__FORMAT;
3278 if (!sym_is_extern(&sym))
3279 continue;
3280 ext_name = elf_sym_str(obj, sym.st_name);
3281 if (!ext_name || !ext_name[0])
3282 continue;
3283
3284 ext = obj->externs;
3285 ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
3286 if (!ext)
3287 return -ENOMEM;
3288 obj->externs = ext;
3289 ext = &ext[obj->nr_extern];
3290 memset(ext, 0, sizeof(*ext));
3291 obj->nr_extern++;
3292
3293 ext->btf_id = find_extern_btf_id(obj->btf, ext_name);
3294 if (ext->btf_id <= 0) {
3295 pr_warn("failed to find BTF for extern '%s': %d\n",
3296 ext_name, ext->btf_id);
3297 return ext->btf_id;
3298 }
3299 t = btf__type_by_id(obj->btf, ext->btf_id);
3300 ext->name = btf__name_by_offset(obj->btf, t->name_off);
3301 ext->sym_idx = i;
3302 ext->is_weak = GELF_ST_BIND(sym.st_info) == STB_WEAK;
3303
3304 ext->sec_btf_id = find_extern_sec_btf_id(obj->btf, ext->btf_id);
3305 if (ext->sec_btf_id <= 0) {
3306 pr_warn("failed to find BTF for extern '%s' [%d] section: %d\n",
3307 ext_name, ext->btf_id, ext->sec_btf_id);
3308 return ext->sec_btf_id;
3309 }
3310 sec = (void *)btf__type_by_id(obj->btf, ext->sec_btf_id);
3311 sec_name = btf__name_by_offset(obj->btf, sec->name_off);
3312
3313 if (strcmp(sec_name, KCONFIG_SEC) == 0) {
3314 if (btf_is_func(t)) {
3315 pr_warn("extern function %s is unsupported under %s section\n",
3316 ext->name, KCONFIG_SEC);
3317 return -ENOTSUP;
3318 }
3319 kcfg_sec = sec;
3320 ext->type = EXT_KCFG;
3321 ext->kcfg.sz = btf__resolve_size(obj->btf, t->type);
3322 if (ext->kcfg.sz <= 0) {
3323 pr_warn("failed to resolve size of extern (kcfg) '%s': %d\n",
3324 ext_name, ext->kcfg.sz);
3325 return ext->kcfg.sz;
3326 }
3327 ext->kcfg.align = btf__align_of(obj->btf, t->type);
3328 if (ext->kcfg.align <= 0) {
3329 pr_warn("failed to determine alignment of extern (kcfg) '%s': %d\n",
3330 ext_name, ext->kcfg.align);
3331 return -EINVAL;
3332 }
3333 ext->kcfg.type = find_kcfg_type(obj->btf, t->type,
3334 &ext->kcfg.is_signed);
3335 if (ext->kcfg.type == KCFG_UNKNOWN) {
3336 pr_warn("extern (kcfg) '%s' type is unsupported\n", ext_name);
3337 return -ENOTSUP;
3338 }
3339 } else if (strcmp(sec_name, KSYMS_SEC) == 0) {
3340 if (btf_is_func(t) && ext->is_weak) {
3341 pr_warn("extern weak function %s is unsupported\n",
3342 ext->name);
3343 return -ENOTSUP;
3344 }
3345 ksym_sec = sec;
3346 ext->type = EXT_KSYM;
3347 skip_mods_and_typedefs(obj->btf, t->type,
3348 &ext->ksym.type_id);
3349 } else {
3350 pr_warn("unrecognized extern section '%s'\n", sec_name);
3351 return -ENOTSUP;
3352 }
3353 }
3354 pr_debug("collected %d externs total\n", obj->nr_extern);
3355
3356 if (!obj->nr_extern)
3357 return 0;
3358
3359 /* sort externs by type, for kcfg ones also by (align, size, name) */
3360 qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
3361
3362 /* for .ksyms section, we need to turn all externs into allocated
3363 * variables in BTF to pass kernel verification; we do this by
3364 * pretending that each extern is a 8-byte variable
3365 */
3366 if (ksym_sec) {
3367 /* find existing 4-byte integer type in BTF to use for fake
3368 * extern variables in DATASEC
3369 */
3370 int int_btf_id = find_int_btf_id(obj->btf);
3371 /* For extern function, a dummy_var added earlier
3372 * will be used to replace the vs->type and
3373 * its name string will be used to refill
3374 * the missing param's name.
3375 */
3376 const struct btf_type *dummy_var;
3377
3378 dummy_var = btf__type_by_id(obj->btf, dummy_var_btf_id);
3379 for (i = 0; i < obj->nr_extern; i++) {
3380 ext = &obj->externs[i];
3381 if (ext->type != EXT_KSYM)
3382 continue;
3383 pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
3384 i, ext->sym_idx, ext->name);
3385 }
3386
3387 sec = ksym_sec;
3388 n = btf_vlen(sec);
3389 for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
3390 struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
3391 struct btf_type *vt;
3392
3393 vt = (void *)btf__type_by_id(obj->btf, vs->type);
3394 ext_name = btf__name_by_offset(obj->btf, vt->name_off);
3395 ext = find_extern_by_name(obj, ext_name);
3396 if (!ext) {
3397 pr_warn("failed to find extern definition for BTF %s '%s'\n",
3398 btf_kind_str(vt), ext_name);
3399 return -ESRCH;
3400 }
3401 if (btf_is_func(vt)) {
3402 const struct btf_type *func_proto;
3403 struct btf_param *param;
3404 int j;
3405
3406 func_proto = btf__type_by_id(obj->btf,
3407 vt->type);
3408 param = btf_params(func_proto);
3409 /* Reuse the dummy_var string if the
3410 * func proto does not have param name.
3411 */
3412 for (j = 0; j < btf_vlen(func_proto); j++)
3413 if (param[j].type && !param[j].name_off)
3414 param[j].name_off =
3415 dummy_var->name_off;
3416 vs->type = dummy_var_btf_id;
3417 vt->info &= ~0xffff;
3418 vt->info |= BTF_FUNC_GLOBAL;
3419 } else {
3420 btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
3421 vt->type = int_btf_id;
3422 }
3423 vs->offset = off;
3424 vs->size = sizeof(int);
3425 }
3426 sec->size = off;
3427 }
3428
3429 if (kcfg_sec) {
3430 sec = kcfg_sec;
3431 /* for kcfg externs calculate their offsets within a .kconfig map */
3432 off = 0;
3433 for (i = 0; i < obj->nr_extern; i++) {
3434 ext = &obj->externs[i];
3435 if (ext->type != EXT_KCFG)
3436 continue;
3437
3438 ext->kcfg.data_off = roundup(off, ext->kcfg.align);
3439 off = ext->kcfg.data_off + ext->kcfg.sz;
3440 pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
3441 i, ext->sym_idx, ext->kcfg.data_off, ext->name);
3442 }
3443 sec->size = off;
3444 n = btf_vlen(sec);
3445 for (i = 0; i < n; i++) {
3446 struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
3447
3448 t = btf__type_by_id(obj->btf, vs->type);
3449 ext_name = btf__name_by_offset(obj->btf, t->name_off);
3450 ext = find_extern_by_name(obj, ext_name);
3451 if (!ext) {
3452 pr_warn("failed to find extern definition for BTF var '%s'\n",
3453 ext_name);
3454 return -ESRCH;
3455 }
3456 btf_var(t)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
3457 vs->offset = ext->kcfg.data_off;
3458 }
3459 }
3460 return 0;
3461 }
3462
3463 struct bpf_program *
bpf_object__find_program_by_title(const struct bpf_object * obj,const char * title)3464 bpf_object__find_program_by_title(const struct bpf_object *obj,
3465 const char *title)
3466 {
3467 struct bpf_program *pos;
3468
3469 bpf_object__for_each_program(pos, obj) {
3470 if (pos->sec_name && !strcmp(pos->sec_name, title))
3471 return pos;
3472 }
3473 return NULL;
3474 }
3475
prog_is_subprog(const struct bpf_object * obj,const struct bpf_program * prog)3476 static bool prog_is_subprog(const struct bpf_object *obj,
3477 const struct bpf_program *prog)
3478 {
3479 /* For legacy reasons, libbpf supports an entry-point BPF programs
3480 * without SEC() attribute, i.e., those in the .text section. But if
3481 * there are 2 or more such programs in the .text section, they all
3482 * must be subprograms called from entry-point BPF programs in
3483 * designated SEC()'tions, otherwise there is no way to distinguish
3484 * which of those programs should be loaded vs which are a subprogram.
3485 * Similarly, if there is a function/program in .text and at least one
3486 * other BPF program with custom SEC() attribute, then we just assume
3487 * .text programs are subprograms (even if they are not called from
3488 * other programs), because libbpf never explicitly supported mixing
3489 * SEC()-designated BPF programs and .text entry-point BPF programs.
3490 */
3491 return prog->sec_idx == obj->efile.text_shndx && obj->nr_programs > 1;
3492 }
3493
3494 struct bpf_program *
bpf_object__find_program_by_name(const struct bpf_object * obj,const char * name)3495 bpf_object__find_program_by_name(const struct bpf_object *obj,
3496 const char *name)
3497 {
3498 struct bpf_program *prog;
3499
3500 bpf_object__for_each_program(prog, obj) {
3501 if (prog_is_subprog(obj, prog))
3502 continue;
3503 if (!strcmp(prog->name, name))
3504 return prog;
3505 }
3506 return NULL;
3507 }
3508
bpf_object__shndx_is_data(const struct bpf_object * obj,int shndx)3509 static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
3510 int shndx)
3511 {
3512 return shndx == obj->efile.data_shndx ||
3513 shndx == obj->efile.bss_shndx ||
3514 shndx == obj->efile.rodata_shndx;
3515 }
3516
bpf_object__shndx_is_maps(const struct bpf_object * obj,int shndx)3517 static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
3518 int shndx)
3519 {
3520 return shndx == obj->efile.maps_shndx ||
3521 shndx == obj->efile.btf_maps_shndx;
3522 }
3523
3524 static enum libbpf_map_type
bpf_object__section_to_libbpf_map_type(const struct bpf_object * obj,int shndx)3525 bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
3526 {
3527 if (shndx == obj->efile.data_shndx)
3528 return LIBBPF_MAP_DATA;
3529 else if (shndx == obj->efile.bss_shndx)
3530 return LIBBPF_MAP_BSS;
3531 else if (shndx == obj->efile.rodata_shndx)
3532 return LIBBPF_MAP_RODATA;
3533 else if (shndx == obj->efile.symbols_shndx)
3534 return LIBBPF_MAP_KCONFIG;
3535 else
3536 return LIBBPF_MAP_UNSPEC;
3537 }
3538
bpf_program__record_reloc(struct bpf_program * prog,struct reloc_desc * reloc_desc,__u32 insn_idx,const char * sym_name,const GElf_Sym * sym,const GElf_Rel * rel)3539 static int bpf_program__record_reloc(struct bpf_program *prog,
3540 struct reloc_desc *reloc_desc,
3541 __u32 insn_idx, const char *sym_name,
3542 const GElf_Sym *sym, const GElf_Rel *rel)
3543 {
3544 struct bpf_insn *insn = &prog->insns[insn_idx];
3545 size_t map_idx, nr_maps = prog->obj->nr_maps;
3546 struct bpf_object *obj = prog->obj;
3547 __u32 shdr_idx = sym->st_shndx;
3548 enum libbpf_map_type type;
3549 const char *sym_sec_name;
3550 struct bpf_map *map;
3551
3552 if (!is_call_insn(insn) && !is_ldimm64_insn(insn)) {
3553 pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
3554 prog->name, sym_name, insn_idx, insn->code);
3555 return -LIBBPF_ERRNO__RELOC;
3556 }
3557
3558 if (sym_is_extern(sym)) {
3559 int sym_idx = GELF_R_SYM(rel->r_info);
3560 int i, n = obj->nr_extern;
3561 struct extern_desc *ext;
3562
3563 for (i = 0; i < n; i++) {
3564 ext = &obj->externs[i];
3565 if (ext->sym_idx == sym_idx)
3566 break;
3567 }
3568 if (i >= n) {
3569 pr_warn("prog '%s': extern relo failed to find extern for '%s' (%d)\n",
3570 prog->name, sym_name, sym_idx);
3571 return -LIBBPF_ERRNO__RELOC;
3572 }
3573 pr_debug("prog '%s': found extern #%d '%s' (sym %d) for insn #%u\n",
3574 prog->name, i, ext->name, ext->sym_idx, insn_idx);
3575 if (insn->code == (BPF_JMP | BPF_CALL))
3576 reloc_desc->type = RELO_EXTERN_FUNC;
3577 else
3578 reloc_desc->type = RELO_EXTERN_VAR;
3579 reloc_desc->insn_idx = insn_idx;
3580 reloc_desc->sym_off = i; /* sym_off stores extern index */
3581 return 0;
3582 }
3583
3584 /* sub-program call relocation */
3585 if (is_call_insn(insn)) {
3586 if (insn->src_reg != BPF_PSEUDO_CALL) {
3587 pr_warn("prog '%s': incorrect bpf_call opcode\n", prog->name);
3588 return -LIBBPF_ERRNO__RELOC;
3589 }
3590 /* text_shndx can be 0, if no default "main" program exists */
3591 if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
3592 sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
3593 pr_warn("prog '%s': bad call relo against '%s' in section '%s'\n",
3594 prog->name, sym_name, sym_sec_name);
3595 return -LIBBPF_ERRNO__RELOC;
3596 }
3597 if (sym->st_value % BPF_INSN_SZ) {
3598 pr_warn("prog '%s': bad call relo against '%s' at offset %zu\n",
3599 prog->name, sym_name, (size_t)sym->st_value);
3600 return -LIBBPF_ERRNO__RELOC;
3601 }
3602 reloc_desc->type = RELO_CALL;
3603 reloc_desc->insn_idx = insn_idx;
3604 reloc_desc->sym_off = sym->st_value;
3605 return 0;
3606 }
3607
3608 if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
3609 pr_warn("prog '%s': invalid relo against '%s' in special section 0x%x; forgot to initialize global var?..\n",
3610 prog->name, sym_name, shdr_idx);
3611 return -LIBBPF_ERRNO__RELOC;
3612 }
3613
3614 /* loading subprog addresses */
3615 if (sym_is_subprog(sym, obj->efile.text_shndx)) {
3616 /* global_func: sym->st_value = offset in the section, insn->imm = 0.
3617 * local_func: sym->st_value = 0, insn->imm = offset in the section.
3618 */
3619 if ((sym->st_value % BPF_INSN_SZ) || (insn->imm % BPF_INSN_SZ)) {
3620 pr_warn("prog '%s': bad subprog addr relo against '%s' at offset %zu+%d\n",
3621 prog->name, sym_name, (size_t)sym->st_value, insn->imm);
3622 return -LIBBPF_ERRNO__RELOC;
3623 }
3624
3625 reloc_desc->type = RELO_SUBPROG_ADDR;
3626 reloc_desc->insn_idx = insn_idx;
3627 reloc_desc->sym_off = sym->st_value;
3628 return 0;
3629 }
3630
3631 type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
3632 sym_sec_name = elf_sec_name(obj, elf_sec_by_idx(obj, shdr_idx));
3633
3634 /* generic map reference relocation */
3635 if (type == LIBBPF_MAP_UNSPEC) {
3636 if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
3637 pr_warn("prog '%s': bad map relo against '%s' in section '%s'\n",
3638 prog->name, sym_name, sym_sec_name);
3639 return -LIBBPF_ERRNO__RELOC;
3640 }
3641 for (map_idx = 0; map_idx < nr_maps; map_idx++) {
3642 map = &obj->maps[map_idx];
3643 if (map->libbpf_type != type ||
3644 map->sec_idx != sym->st_shndx ||
3645 map->sec_offset != sym->st_value)
3646 continue;
3647 pr_debug("prog '%s': found map %zd (%s, sec %d, off %zu) for insn #%u\n",
3648 prog->name, map_idx, map->name, map->sec_idx,
3649 map->sec_offset, insn_idx);
3650 break;
3651 }
3652 if (map_idx >= nr_maps) {
3653 pr_warn("prog '%s': map relo failed to find map for section '%s', off %zu\n",
3654 prog->name, sym_sec_name, (size_t)sym->st_value);
3655 return -LIBBPF_ERRNO__RELOC;
3656 }
3657 reloc_desc->type = RELO_LD64;
3658 reloc_desc->insn_idx = insn_idx;
3659 reloc_desc->map_idx = map_idx;
3660 reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
3661 return 0;
3662 }
3663
3664 /* global data map relocation */
3665 if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
3666 pr_warn("prog '%s': bad data relo against section '%s'\n",
3667 prog->name, sym_sec_name);
3668 return -LIBBPF_ERRNO__RELOC;
3669 }
3670 for (map_idx = 0; map_idx < nr_maps; map_idx++) {
3671 map = &obj->maps[map_idx];
3672 if (map->libbpf_type != type)
3673 continue;
3674 pr_debug("prog '%s': found data map %zd (%s, sec %d, off %zu) for insn %u\n",
3675 prog->name, map_idx, map->name, map->sec_idx,
3676 map->sec_offset, insn_idx);
3677 break;
3678 }
3679 if (map_idx >= nr_maps) {
3680 pr_warn("prog '%s': data relo failed to find map for section '%s'\n",
3681 prog->name, sym_sec_name);
3682 return -LIBBPF_ERRNO__RELOC;
3683 }
3684
3685 reloc_desc->type = RELO_DATA;
3686 reloc_desc->insn_idx = insn_idx;
3687 reloc_desc->map_idx = map_idx;
3688 reloc_desc->sym_off = sym->st_value;
3689 return 0;
3690 }
3691
prog_contains_insn(const struct bpf_program * prog,size_t insn_idx)3692 static bool prog_contains_insn(const struct bpf_program *prog, size_t insn_idx)
3693 {
3694 return insn_idx >= prog->sec_insn_off &&
3695 insn_idx < prog->sec_insn_off + prog->sec_insn_cnt;
3696 }
3697
find_prog_by_sec_insn(const struct bpf_object * obj,size_t sec_idx,size_t insn_idx)3698 static struct bpf_program *find_prog_by_sec_insn(const struct bpf_object *obj,
3699 size_t sec_idx, size_t insn_idx)
3700 {
3701 int l = 0, r = obj->nr_programs - 1, m;
3702 struct bpf_program *prog;
3703
3704 while (l < r) {
3705 m = l + (r - l + 1) / 2;
3706 prog = &obj->programs[m];
3707
3708 if (prog->sec_idx < sec_idx ||
3709 (prog->sec_idx == sec_idx && prog->sec_insn_off <= insn_idx))
3710 l = m;
3711 else
3712 r = m - 1;
3713 }
3714 /* matching program could be at index l, but it still might be the
3715 * wrong one, so we need to double check conditions for the last time
3716 */
3717 prog = &obj->programs[l];
3718 if (prog->sec_idx == sec_idx && prog_contains_insn(prog, insn_idx))
3719 return prog;
3720 return NULL;
3721 }
3722
3723 static int
bpf_object__collect_prog_relos(struct bpf_object * obj,GElf_Shdr * shdr,Elf_Data * data)3724 bpf_object__collect_prog_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data)
3725 {
3726 Elf_Data *symbols = obj->efile.symbols;
3727 const char *relo_sec_name, *sec_name;
3728 size_t sec_idx = shdr->sh_info;
3729 struct bpf_program *prog;
3730 struct reloc_desc *relos;
3731 int err, i, nrels;
3732 const char *sym_name;
3733 __u32 insn_idx;
3734 Elf_Scn *scn;
3735 Elf_Data *scn_data;
3736 GElf_Sym sym;
3737 GElf_Rel rel;
3738
3739 scn = elf_sec_by_idx(obj, sec_idx);
3740 scn_data = elf_sec_data(obj, scn);
3741
3742 relo_sec_name = elf_sec_str(obj, shdr->sh_name);
3743 sec_name = elf_sec_name(obj, scn);
3744 if (!relo_sec_name || !sec_name)
3745 return -EINVAL;
3746
3747 pr_debug("sec '%s': collecting relocation for section(%zu) '%s'\n",
3748 relo_sec_name, sec_idx, sec_name);
3749 nrels = shdr->sh_size / shdr->sh_entsize;
3750
3751 for (i = 0; i < nrels; i++) {
3752 if (!gelf_getrel(data, i, &rel)) {
3753 pr_warn("sec '%s': failed to get relo #%d\n", relo_sec_name, i);
3754 return -LIBBPF_ERRNO__FORMAT;
3755 }
3756 if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
3757 pr_warn("sec '%s': symbol 0x%zx not found for relo #%d\n",
3758 relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i);
3759 return -LIBBPF_ERRNO__FORMAT;
3760 }
3761
3762 if (rel.r_offset % BPF_INSN_SZ || rel.r_offset >= scn_data->d_size) {
3763 pr_warn("sec '%s': invalid offset 0x%zx for relo #%d\n",
3764 relo_sec_name, (size_t)GELF_R_SYM(rel.r_info), i);
3765 return -LIBBPF_ERRNO__FORMAT;
3766 }
3767
3768 insn_idx = rel.r_offset / BPF_INSN_SZ;
3769 /* relocations against static functions are recorded as
3770 * relocations against the section that contains a function;
3771 * in such case, symbol will be STT_SECTION and sym.st_name
3772 * will point to empty string (0), so fetch section name
3773 * instead
3774 */
3775 if (GELF_ST_TYPE(sym.st_info) == STT_SECTION && sym.st_name == 0)
3776 sym_name = elf_sec_name(obj, elf_sec_by_idx(obj, sym.st_shndx));
3777 else
3778 sym_name = elf_sym_str(obj, sym.st_name);
3779 sym_name = sym_name ?: "<?";
3780
3781 pr_debug("sec '%s': relo #%d: insn #%u against '%s'\n",
3782 relo_sec_name, i, insn_idx, sym_name);
3783
3784 prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
3785 if (!prog) {
3786 pr_debug("sec '%s': relo #%d: couldn't find program in section '%s' for insn #%u, probably overridden weak function, skipping...\n",
3787 relo_sec_name, i, sec_name, insn_idx);
3788 continue;
3789 }
3790
3791 relos = libbpf_reallocarray(prog->reloc_desc,
3792 prog->nr_reloc + 1, sizeof(*relos));
3793 if (!relos)
3794 return -ENOMEM;
3795 prog->reloc_desc = relos;
3796
3797 /* adjust insn_idx to local BPF program frame of reference */
3798 insn_idx -= prog->sec_insn_off;
3799 err = bpf_program__record_reloc(prog, &relos[prog->nr_reloc],
3800 insn_idx, sym_name, &sym, &rel);
3801 if (err)
3802 return err;
3803
3804 prog->nr_reloc++;
3805 }
3806 return 0;
3807 }
3808
bpf_map_find_btf_info(struct bpf_object * obj,struct bpf_map * map)3809 static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
3810 {
3811 struct bpf_map_def *def = &map->def;
3812 __u32 key_type_id = 0, value_type_id = 0;
3813 int ret;
3814
3815 /* if it's BTF-defined map, we don't need to search for type IDs.
3816 * For struct_ops map, it does not need btf_key_type_id and
3817 * btf_value_type_id.
3818 */
3819 if (map->sec_idx == obj->efile.btf_maps_shndx ||
3820 bpf_map__is_struct_ops(map))
3821 return 0;
3822
3823 if (!bpf_map__is_internal(map)) {
3824 ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,
3825 def->value_size, &key_type_id,
3826 &value_type_id);
3827 } else {
3828 /*
3829 * LLVM annotates global data differently in BTF, that is,
3830 * only as '.data', '.bss' or '.rodata'.
3831 */
3832 ret = btf__find_by_name(obj->btf,
3833 libbpf_type_to_btf_name[map->libbpf_type]);
3834 }
3835 if (ret < 0)
3836 return ret;
3837
3838 map->btf_key_type_id = key_type_id;
3839 map->btf_value_type_id = bpf_map__is_internal(map) ?
3840 ret : value_type_id;
3841 return 0;
3842 }
3843
bpf_map__reuse_fd(struct bpf_map * map,int fd)3844 int bpf_map__reuse_fd(struct bpf_map *map, int fd)
3845 {
3846 struct bpf_map_info info = {};
3847 __u32 len = sizeof(info);
3848 int new_fd, err;
3849 char *new_name;
3850
3851 err = bpf_obj_get_info_by_fd(fd, &info, &len);
3852 if (err)
3853 return err;
3854
3855 new_name = strdup(info.name);
3856 if (!new_name)
3857 return -errno;
3858
3859 new_fd = open("/", O_RDONLY | O_CLOEXEC);
3860 if (new_fd < 0) {
3861 err = -errno;
3862 goto err_free_new_name;
3863 }
3864
3865 new_fd = dup3(fd, new_fd, O_CLOEXEC);
3866 if (new_fd < 0) {
3867 err = -errno;
3868 goto err_close_new_fd;
3869 }
3870
3871 err = zclose(map->fd);
3872 if (err) {
3873 err = -errno;
3874 goto err_close_new_fd;
3875 }
3876 free(map->name);
3877
3878 map->fd = new_fd;
3879 map->name = new_name;
3880 map->def.type = info.type;
3881 map->def.key_size = info.key_size;
3882 map->def.value_size = info.value_size;
3883 map->def.max_entries = info.max_entries;
3884 map->def.map_flags = info.map_flags;
3885 map->btf_key_type_id = info.btf_key_type_id;
3886 map->btf_value_type_id = info.btf_value_type_id;
3887 map->reused = true;
3888
3889 return 0;
3890
3891 err_close_new_fd:
3892 close(new_fd);
3893 err_free_new_name:
3894 free(new_name);
3895 return err;
3896 }
3897
bpf_map__max_entries(const struct bpf_map * map)3898 __u32 bpf_map__max_entries(const struct bpf_map *map)
3899 {
3900 return map->def.max_entries;
3901 }
3902
bpf_map__inner_map(struct bpf_map * map)3903 struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
3904 {
3905 if (!bpf_map_type__is_map_in_map(map->def.type))
3906 return NULL;
3907
3908 return map->inner_map;
3909 }
3910
bpf_map__set_max_entries(struct bpf_map * map,__u32 max_entries)3911 int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
3912 {
3913 if (map->fd >= 0)
3914 return -EBUSY;
3915 map->def.max_entries = max_entries;
3916 return 0;
3917 }
3918
bpf_map__resize(struct bpf_map * map,__u32 max_entries)3919 int bpf_map__resize(struct bpf_map *map, __u32 max_entries)
3920 {
3921 if (!map || !max_entries)
3922 return -EINVAL;
3923
3924 return bpf_map__set_max_entries(map, max_entries);
3925 }
3926
3927 static int
bpf_object__probe_loading(struct bpf_object * obj)3928 bpf_object__probe_loading(struct bpf_object *obj)
3929 {
3930 struct bpf_load_program_attr attr;
3931 char *cp, errmsg[STRERR_BUFSIZE];
3932 struct bpf_insn insns[] = {
3933 BPF_MOV64_IMM(BPF_REG_0, 0),
3934 BPF_EXIT_INSN(),
3935 };
3936 int ret;
3937
3938 /* make sure basic loading works */
3939
3940 memset(&attr, 0, sizeof(attr));
3941 attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
3942 attr.insns = insns;
3943 attr.insns_cnt = ARRAY_SIZE(insns);
3944 attr.license = "GPL";
3945
3946 ret = bpf_load_program_xattr(&attr, NULL, 0);
3947 if (ret < 0) {
3948 ret = errno;
3949 cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
3950 pr_warn("Error in %s():%s(%d). Couldn't load trivial BPF "
3951 "program. Make sure your kernel supports BPF "
3952 "(CONFIG_BPF_SYSCALL=y) and/or that RLIMIT_MEMLOCK is "
3953 "set to big enough value.\n", __func__, cp, ret);
3954 return -ret;
3955 }
3956 close(ret);
3957
3958 return 0;
3959 }
3960
probe_fd(int fd)3961 static int probe_fd(int fd)
3962 {
3963 if (fd >= 0)
3964 close(fd);
3965 return fd >= 0;
3966 }
3967
probe_kern_prog_name(void)3968 static int probe_kern_prog_name(void)
3969 {
3970 struct bpf_load_program_attr attr;
3971 struct bpf_insn insns[] = {
3972 BPF_MOV64_IMM(BPF_REG_0, 0),
3973 BPF_EXIT_INSN(),
3974 };
3975 int ret;
3976
3977 /* make sure loading with name works */
3978
3979 memset(&attr, 0, sizeof(attr));
3980 attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
3981 attr.insns = insns;
3982 attr.insns_cnt = ARRAY_SIZE(insns);
3983 attr.license = "GPL";
3984 attr.name = "test";
3985 ret = bpf_load_program_xattr(&attr, NULL, 0);
3986 return probe_fd(ret);
3987 }
3988
probe_kern_global_data(void)3989 static int probe_kern_global_data(void)
3990 {
3991 struct bpf_load_program_attr prg_attr;
3992 struct bpf_create_map_attr map_attr;
3993 char *cp, errmsg[STRERR_BUFSIZE];
3994 struct bpf_insn insns[] = {
3995 BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
3996 BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
3997 BPF_MOV64_IMM(BPF_REG_0, 0),
3998 BPF_EXIT_INSN(),
3999 };
4000 int ret, map;
4001
4002 memset(&map_attr, 0, sizeof(map_attr));
4003 map_attr.map_type = BPF_MAP_TYPE_ARRAY;
4004 map_attr.key_size = sizeof(int);
4005 map_attr.value_size = 32;
4006 map_attr.max_entries = 1;
4007
4008 map = bpf_create_map_xattr(&map_attr);
4009 if (map < 0) {
4010 ret = -errno;
4011 cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
4012 pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
4013 __func__, cp, -ret);
4014 return ret;
4015 }
4016
4017 insns[0].imm = map;
4018
4019 memset(&prg_attr, 0, sizeof(prg_attr));
4020 prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
4021 prg_attr.insns = insns;
4022 prg_attr.insns_cnt = ARRAY_SIZE(insns);
4023 prg_attr.license = "GPL";
4024
4025 ret = bpf_load_program_xattr(&prg_attr, NULL, 0);
4026 close(map);
4027 return probe_fd(ret);
4028 }
4029
probe_kern_btf(void)4030 static int probe_kern_btf(void)
4031 {
4032 static const char strs[] = "\0int";
4033 __u32 types[] = {
4034 /* int */
4035 BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
4036 };
4037
4038 return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
4039 strs, sizeof(strs)));
4040 }
4041
probe_kern_btf_func(void)4042 static int probe_kern_btf_func(void)
4043 {
4044 static const char strs[] = "\0int\0x\0a";
4045 /* void x(int a) {} */
4046 __u32 types[] = {
4047 /* int */
4048 BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
4049 /* FUNC_PROTO */ /* [2] */
4050 BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
4051 BTF_PARAM_ENC(7, 1),
4052 /* FUNC x */ /* [3] */
4053 BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
4054 };
4055
4056 return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
4057 strs, sizeof(strs)));
4058 }
4059
probe_kern_btf_func_global(void)4060 static int probe_kern_btf_func_global(void)
4061 {
4062 static const char strs[] = "\0int\0x\0a";
4063 /* static void x(int a) {} */
4064 __u32 types[] = {
4065 /* int */
4066 BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
4067 /* FUNC_PROTO */ /* [2] */
4068 BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
4069 BTF_PARAM_ENC(7, 1),
4070 /* FUNC x BTF_FUNC_GLOBAL */ /* [3] */
4071 BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, BTF_FUNC_GLOBAL), 2),
4072 };
4073
4074 return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
4075 strs, sizeof(strs)));
4076 }
4077
probe_kern_btf_datasec(void)4078 static int probe_kern_btf_datasec(void)
4079 {
4080 static const char strs[] = "\0x\0.data";
4081 /* static int a; */
4082 __u32 types[] = {
4083 /* int */
4084 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
4085 /* VAR x */ /* [2] */
4086 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
4087 BTF_VAR_STATIC,
4088 /* DATASEC val */ /* [3] */
4089 BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
4090 BTF_VAR_SECINFO_ENC(2, 0, 4),
4091 };
4092
4093 return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
4094 strs, sizeof(strs)));
4095 }
4096
probe_kern_btf_float(void)4097 static int probe_kern_btf_float(void)
4098 {
4099 static const char strs[] = "\0float";
4100 __u32 types[] = {
4101 /* float */
4102 BTF_TYPE_FLOAT_ENC(1, 4),
4103 };
4104
4105 return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
4106 strs, sizeof(strs)));
4107 }
4108
probe_kern_array_mmap(void)4109 static int probe_kern_array_mmap(void)
4110 {
4111 struct bpf_create_map_attr attr = {
4112 .map_type = BPF_MAP_TYPE_ARRAY,
4113 .map_flags = BPF_F_MMAPABLE,
4114 .key_size = sizeof(int),
4115 .value_size = sizeof(int),
4116 .max_entries = 1,
4117 };
4118
4119 return probe_fd(bpf_create_map_xattr(&attr));
4120 }
4121
probe_kern_exp_attach_type(void)4122 static int probe_kern_exp_attach_type(void)
4123 {
4124 struct bpf_load_program_attr attr;
4125 struct bpf_insn insns[] = {
4126 BPF_MOV64_IMM(BPF_REG_0, 0),
4127 BPF_EXIT_INSN(),
4128 };
4129
4130 memset(&attr, 0, sizeof(attr));
4131 /* use any valid combination of program type and (optional)
4132 * non-zero expected attach type (i.e., not a BPF_CGROUP_INET_INGRESS)
4133 * to see if kernel supports expected_attach_type field for
4134 * BPF_PROG_LOAD command
4135 */
4136 attr.prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
4137 attr.expected_attach_type = BPF_CGROUP_INET_SOCK_CREATE;
4138 attr.insns = insns;
4139 attr.insns_cnt = ARRAY_SIZE(insns);
4140 attr.license = "GPL";
4141
4142 return probe_fd(bpf_load_program_xattr(&attr, NULL, 0));
4143 }
4144
probe_kern_probe_read_kernel(void)4145 static int probe_kern_probe_read_kernel(void)
4146 {
4147 struct bpf_load_program_attr attr;
4148 struct bpf_insn insns[] = {
4149 BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */
4150 BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */
4151 BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */
4152 BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */
4153 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
4154 BPF_EXIT_INSN(),
4155 };
4156
4157 memset(&attr, 0, sizeof(attr));
4158 attr.prog_type = BPF_PROG_TYPE_KPROBE;
4159 attr.insns = insns;
4160 attr.insns_cnt = ARRAY_SIZE(insns);
4161 attr.license = "GPL";
4162
4163 return probe_fd(bpf_load_program_xattr(&attr, NULL, 0));
4164 }
4165
probe_prog_bind_map(void)4166 static int probe_prog_bind_map(void)
4167 {
4168 struct bpf_load_program_attr prg_attr;
4169 struct bpf_create_map_attr map_attr;
4170 char *cp, errmsg[STRERR_BUFSIZE];
4171 struct bpf_insn insns[] = {
4172 BPF_MOV64_IMM(BPF_REG_0, 0),
4173 BPF_EXIT_INSN(),
4174 };
4175 int ret, map, prog;
4176
4177 memset(&map_attr, 0, sizeof(map_attr));
4178 map_attr.map_type = BPF_MAP_TYPE_ARRAY;
4179 map_attr.key_size = sizeof(int);
4180 map_attr.value_size = 32;
4181 map_attr.max_entries = 1;
4182
4183 map = bpf_create_map_xattr(&map_attr);
4184 if (map < 0) {
4185 ret = -errno;
4186 cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg));
4187 pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
4188 __func__, cp, -ret);
4189 return ret;
4190 }
4191
4192 memset(&prg_attr, 0, sizeof(prg_attr));
4193 prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
4194 prg_attr.insns = insns;
4195 prg_attr.insns_cnt = ARRAY_SIZE(insns);
4196 prg_attr.license = "GPL";
4197
4198 prog = bpf_load_program_xattr(&prg_attr, NULL, 0);
4199 if (prog < 0) {
4200 close(map);
4201 return 0;
4202 }
4203
4204 ret = bpf_prog_bind_map(prog, map, NULL);
4205
4206 close(map);
4207 close(prog);
4208
4209 return ret >= 0;
4210 }
4211
probe_module_btf(void)4212 static int probe_module_btf(void)
4213 {
4214 static const char strs[] = "\0int";
4215 __u32 types[] = {
4216 /* int */
4217 BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),
4218 };
4219 struct bpf_btf_info info;
4220 __u32 len = sizeof(info);
4221 char name[16];
4222 int fd, err;
4223
4224 fd = libbpf__load_raw_btf((char *)types, sizeof(types), strs, sizeof(strs));
4225 if (fd < 0)
4226 return 0; /* BTF not supported at all */
4227
4228 memset(&info, 0, sizeof(info));
4229 info.name = ptr_to_u64(name);
4230 info.name_len = sizeof(name);
4231
4232 /* check that BPF_OBJ_GET_INFO_BY_FD supports specifying name pointer;
4233 * kernel's module BTF support coincides with support for
4234 * name/name_len fields in struct bpf_btf_info.
4235 */
4236 err = bpf_obj_get_info_by_fd(fd, &info, &len);
4237 close(fd);
4238 return !err;
4239 }
4240
4241 enum kern_feature_result {
4242 FEAT_UNKNOWN = 0,
4243 FEAT_SUPPORTED = 1,
4244 FEAT_MISSING = 2,
4245 };
4246
4247 typedef int (*feature_probe_fn)(void);
4248
4249 static struct kern_feature_desc {
4250 const char *desc;
4251 feature_probe_fn probe;
4252 enum kern_feature_result res;
4253 } feature_probes[__FEAT_CNT] = {
4254 [FEAT_PROG_NAME] = {
4255 "BPF program name", probe_kern_prog_name,
4256 },
4257 [FEAT_GLOBAL_DATA] = {
4258 "global variables", probe_kern_global_data,
4259 },
4260 [FEAT_BTF] = {
4261 "minimal BTF", probe_kern_btf,
4262 },
4263 [FEAT_BTF_FUNC] = {
4264 "BTF functions", probe_kern_btf_func,
4265 },
4266 [FEAT_BTF_GLOBAL_FUNC] = {
4267 "BTF global function", probe_kern_btf_func_global,
4268 },
4269 [FEAT_BTF_DATASEC] = {
4270 "BTF data section and variable", probe_kern_btf_datasec,
4271 },
4272 [FEAT_ARRAY_MMAP] = {
4273 "ARRAY map mmap()", probe_kern_array_mmap,
4274 },
4275 [FEAT_EXP_ATTACH_TYPE] = {
4276 "BPF_PROG_LOAD expected_attach_type attribute",
4277 probe_kern_exp_attach_type,
4278 },
4279 [FEAT_PROBE_READ_KERN] = {
4280 "bpf_probe_read_kernel() helper", probe_kern_probe_read_kernel,
4281 },
4282 [FEAT_PROG_BIND_MAP] = {
4283 "BPF_PROG_BIND_MAP support", probe_prog_bind_map,
4284 },
4285 [FEAT_MODULE_BTF] = {
4286 "module BTF support", probe_module_btf,
4287 },
4288 [FEAT_BTF_FLOAT] = {
4289 "BTF_KIND_FLOAT support", probe_kern_btf_float,
4290 },
4291 };
4292
kernel_supports(enum kern_feature_id feat_id)4293 static bool kernel_supports(enum kern_feature_id feat_id)
4294 {
4295 struct kern_feature_desc *feat = &feature_probes[feat_id];
4296 int ret;
4297
4298 if (READ_ONCE(feat->res) == FEAT_UNKNOWN) {
4299 ret = feat->probe();
4300 if (ret > 0) {
4301 WRITE_ONCE(feat->res, FEAT_SUPPORTED);
4302 } else if (ret == 0) {
4303 WRITE_ONCE(feat->res, FEAT_MISSING);
4304 } else {
4305 pr_warn("Detection of kernel %s support failed: %d\n", feat->desc, ret);
4306 WRITE_ONCE(feat->res, FEAT_MISSING);
4307 }
4308 }
4309
4310 return READ_ONCE(feat->res) == FEAT_SUPPORTED;
4311 }
4312
map_is_reuse_compat(const struct bpf_map * map,int map_fd)4313 static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
4314 {
4315 struct bpf_map_info map_info = {};
4316 char msg[STRERR_BUFSIZE];
4317 __u32 map_info_len;
4318
4319 map_info_len = sizeof(map_info);
4320
4321 if (bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len)) {
4322 pr_warn("failed to get map info for map FD %d: %s\n",
4323 map_fd, libbpf_strerror_r(errno, msg, sizeof(msg)));
4324 return false;
4325 }
4326
4327 return (map_info.type == map->def.type &&
4328 map_info.key_size == map->def.key_size &&
4329 map_info.value_size == map->def.value_size &&
4330 map_info.max_entries == map->def.max_entries &&
4331 map_info.map_flags == map->def.map_flags);
4332 }
4333
4334 static int
bpf_object__reuse_map(struct bpf_map * map)4335 bpf_object__reuse_map(struct bpf_map *map)
4336 {
4337 char *cp, errmsg[STRERR_BUFSIZE];
4338 int err, pin_fd;
4339
4340 pin_fd = bpf_obj_get(map->pin_path);
4341 if (pin_fd < 0) {
4342 err = -errno;
4343 if (err == -ENOENT) {
4344 pr_debug("found no pinned map to reuse at '%s'\n",
4345 map->pin_path);
4346 return 0;
4347 }
4348
4349 cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
4350 pr_warn("couldn't retrieve pinned map '%s': %s\n",
4351 map->pin_path, cp);
4352 return err;
4353 }
4354
4355 if (!map_is_reuse_compat(map, pin_fd)) {
4356 pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
4357 map->pin_path);
4358 close(pin_fd);
4359 return -EINVAL;
4360 }
4361
4362 err = bpf_map__reuse_fd(map, pin_fd);
4363 if (err) {
4364 close(pin_fd);
4365 return err;
4366 }
4367 map->pinned = true;
4368 pr_debug("reused pinned map at '%s'\n", map->pin_path);
4369
4370 return 0;
4371 }
4372
4373 static int
bpf_object__populate_internal_map(struct bpf_object * obj,struct bpf_map * map)4374 bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
4375 {
4376 enum libbpf_map_type map_type = map->libbpf_type;
4377 char *cp, errmsg[STRERR_BUFSIZE];
4378 int err, zero = 0;
4379
4380 err = bpf_map_update_elem(map->fd, &zero, map->mmaped, 0);
4381 if (err) {
4382 err = -errno;
4383 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
4384 pr_warn("Error setting initial map(%s) contents: %s\n",
4385 map->name, cp);
4386 return err;
4387 }
4388
4389 /* Freeze .rodata and .kconfig map as read-only from syscall side. */
4390 if (map_type == LIBBPF_MAP_RODATA || map_type == LIBBPF_MAP_KCONFIG) {
4391 err = bpf_map_freeze(map->fd);
4392 if (err) {
4393 err = -errno;
4394 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
4395 pr_warn("Error freezing map(%s) as read-only: %s\n",
4396 map->name, cp);
4397 return err;
4398 }
4399 }
4400 return 0;
4401 }
4402
4403 static void bpf_map__destroy(struct bpf_map *map);
4404
bpf_object__create_map(struct bpf_object * obj,struct bpf_map * map)4405 static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map)
4406 {
4407 struct bpf_create_map_attr create_attr;
4408 struct bpf_map_def *def = &map->def;
4409
4410 memset(&create_attr, 0, sizeof(create_attr));
4411
4412 if (kernel_supports(FEAT_PROG_NAME))
4413 create_attr.name = map->name;
4414 create_attr.map_ifindex = map->map_ifindex;
4415 create_attr.map_type = def->type;
4416 create_attr.map_flags = def->map_flags;
4417 create_attr.key_size = def->key_size;
4418 create_attr.value_size = def->value_size;
4419 create_attr.numa_node = map->numa_node;
4420
4421 if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) {
4422 int nr_cpus;
4423
4424 nr_cpus = libbpf_num_possible_cpus();
4425 if (nr_cpus < 0) {
4426 pr_warn("map '%s': failed to determine number of system CPUs: %d\n",
4427 map->name, nr_cpus);
4428 return nr_cpus;
4429 }
4430 pr_debug("map '%s': setting size to %d\n", map->name, nr_cpus);
4431 create_attr.max_entries = nr_cpus;
4432 } else {
4433 create_attr.max_entries = def->max_entries;
4434 }
4435
4436 if (bpf_map__is_struct_ops(map))
4437 create_attr.btf_vmlinux_value_type_id =
4438 map->btf_vmlinux_value_type_id;
4439
4440 create_attr.btf_fd = 0;
4441 create_attr.btf_key_type_id = 0;
4442 create_attr.btf_value_type_id = 0;
4443 if (obj->btf && btf__fd(obj->btf) >= 0 && !bpf_map_find_btf_info(obj, map)) {
4444 create_attr.btf_fd = btf__fd(obj->btf);
4445 create_attr.btf_key_type_id = map->btf_key_type_id;
4446 create_attr.btf_value_type_id = map->btf_value_type_id;
4447 }
4448
4449 if (bpf_map_type__is_map_in_map(def->type)) {
4450 if (map->inner_map) {
4451 int err;
4452
4453 err = bpf_object__create_map(obj, map->inner_map);
4454 if (err) {
4455 pr_warn("map '%s': failed to create inner map: %d\n",
4456 map->name, err);
4457 return err;
4458 }
4459 map->inner_map_fd = bpf_map__fd(map->inner_map);
4460 }
4461 if (map->inner_map_fd >= 0)
4462 create_attr.inner_map_fd = map->inner_map_fd;
4463 }
4464
4465 map->fd = bpf_create_map_xattr(&create_attr);
4466 if (map->fd < 0 && (create_attr.btf_key_type_id ||
4467 create_attr.btf_value_type_id)) {
4468 char *cp, errmsg[STRERR_BUFSIZE];
4469 int err = -errno;
4470
4471 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
4472 pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
4473 map->name, cp, err);
4474 create_attr.btf_fd = 0;
4475 create_attr.btf_key_type_id = 0;
4476 create_attr.btf_value_type_id = 0;
4477 map->btf_key_type_id = 0;
4478 map->btf_value_type_id = 0;
4479 map->fd = bpf_create_map_xattr(&create_attr);
4480 }
4481
4482 if (map->fd < 0)
4483 return -errno;
4484
4485 if (bpf_map_type__is_map_in_map(def->type) && map->inner_map) {
4486 bpf_map__destroy(map->inner_map);
4487 zfree(&map->inner_map);
4488 }
4489
4490 return 0;
4491 }
4492
init_map_slots(struct bpf_map * map)4493 static int init_map_slots(struct bpf_map *map)
4494 {
4495 const struct bpf_map *targ_map;
4496 unsigned int i;
4497 int fd, err;
4498
4499 for (i = 0; i < map->init_slots_sz; i++) {
4500 if (!map->init_slots[i])
4501 continue;
4502
4503 targ_map = map->init_slots[i];
4504 fd = bpf_map__fd(targ_map);
4505 err = bpf_map_update_elem(map->fd, &i, &fd, 0);
4506 if (err) {
4507 err = -errno;
4508 pr_warn("map '%s': failed to initialize slot [%d] to map '%s' fd=%d: %d\n",
4509 map->name, i, targ_map->name,
4510 fd, err);
4511 return err;
4512 }
4513 pr_debug("map '%s': slot [%d] set to map '%s' fd=%d\n",
4514 map->name, i, targ_map->name, fd);
4515 }
4516
4517 zfree(&map->init_slots);
4518 map->init_slots_sz = 0;
4519
4520 return 0;
4521 }
4522
4523 static int
bpf_object__create_maps(struct bpf_object * obj)4524 bpf_object__create_maps(struct bpf_object *obj)
4525 {
4526 struct bpf_map *map;
4527 char *cp, errmsg[STRERR_BUFSIZE];
4528 unsigned int i, j;
4529 int err;
4530
4531 for (i = 0; i < obj->nr_maps; i++) {
4532 map = &obj->maps[i];
4533
4534 if (map->pin_path) {
4535 err = bpf_object__reuse_map(map);
4536 if (err) {
4537 pr_warn("map '%s': error reusing pinned map\n",
4538 map->name);
4539 goto err_out;
4540 }
4541 }
4542
4543 if (map->fd >= 0) {
4544 pr_debug("map '%s': skipping creation (preset fd=%d)\n",
4545 map->name, map->fd);
4546 } else {
4547 err = bpf_object__create_map(obj, map);
4548 if (err)
4549 goto err_out;
4550
4551 pr_debug("map '%s': created successfully, fd=%d\n",
4552 map->name, map->fd);
4553
4554 if (bpf_map__is_internal(map)) {
4555 err = bpf_object__populate_internal_map(obj, map);
4556 if (err < 0) {
4557 zclose(map->fd);
4558 goto err_out;
4559 }
4560 }
4561
4562 if (map->init_slots_sz) {
4563 err = init_map_slots(map);
4564 if (err < 0) {
4565 zclose(map->fd);
4566 goto err_out;
4567 }
4568 }
4569 }
4570
4571 if (map->pin_path && !map->pinned) {
4572 err = bpf_map__pin(map, NULL);
4573 if (err) {
4574 pr_warn("map '%s': failed to auto-pin at '%s': %d\n",
4575 map->name, map->pin_path, err);
4576 zclose(map->fd);
4577 goto err_out;
4578 }
4579 }
4580 }
4581
4582 return 0;
4583
4584 err_out:
4585 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
4586 pr_warn("map '%s': failed to create: %s(%d)\n", map->name, cp, err);
4587 pr_perm_msg(err);
4588 for (j = 0; j < i; j++)
4589 zclose(obj->maps[j].fd);
4590 return err;
4591 }
4592
4593 #define BPF_CORE_SPEC_MAX_LEN 64
4594
4595 /* represents BPF CO-RE field or array element accessor */
4596 struct bpf_core_accessor {
4597 __u32 type_id; /* struct/union type or array element type */
4598 __u32 idx; /* field index or array index */
4599 const char *name; /* field name or NULL for array accessor */
4600 };
4601
4602 struct bpf_core_spec {
4603 const struct btf *btf;
4604 /* high-level spec: named fields and array indices only */
4605 struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
4606 /* original unresolved (no skip_mods_or_typedefs) root type ID */
4607 __u32 root_type_id;
4608 /* CO-RE relocation kind */
4609 enum bpf_core_relo_kind relo_kind;
4610 /* high-level spec length */
4611 int len;
4612 /* raw, low-level spec: 1-to-1 with accessor spec string */
4613 int raw_spec[BPF_CORE_SPEC_MAX_LEN];
4614 /* raw spec length */
4615 int raw_len;
4616 /* field bit offset represented by spec */
4617 __u32 bit_offset;
4618 };
4619
str_is_empty(const char * s)4620 static bool str_is_empty(const char *s)
4621 {
4622 return !s || !s[0];
4623 }
4624
is_flex_arr(const struct btf * btf,const struct bpf_core_accessor * acc,const struct btf_array * arr)4625 static bool is_flex_arr(const struct btf *btf,
4626 const struct bpf_core_accessor *acc,
4627 const struct btf_array *arr)
4628 {
4629 const struct btf_type *t;
4630
4631 /* not a flexible array, if not inside a struct or has non-zero size */
4632 if (!acc->name || arr->nelems > 0)
4633 return false;
4634
4635 /* has to be the last member of enclosing struct */
4636 t = btf__type_by_id(btf, acc->type_id);
4637 return acc->idx == btf_vlen(t) - 1;
4638 }
4639
core_relo_kind_str(enum bpf_core_relo_kind kind)4640 static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
4641 {
4642 switch (kind) {
4643 case BPF_FIELD_BYTE_OFFSET: return "byte_off";
4644 case BPF_FIELD_BYTE_SIZE: return "byte_sz";
4645 case BPF_FIELD_EXISTS: return "field_exists";
4646 case BPF_FIELD_SIGNED: return "signed";
4647 case BPF_FIELD_LSHIFT_U64: return "lshift_u64";
4648 case BPF_FIELD_RSHIFT_U64: return "rshift_u64";
4649 case BPF_TYPE_ID_LOCAL: return "local_type_id";
4650 case BPF_TYPE_ID_TARGET: return "target_type_id";
4651 case BPF_TYPE_EXISTS: return "type_exists";
4652 case BPF_TYPE_SIZE: return "type_size";
4653 case BPF_ENUMVAL_EXISTS: return "enumval_exists";
4654 case BPF_ENUMVAL_VALUE: return "enumval_value";
4655 default: return "unknown";
4656 }
4657 }
4658
core_relo_is_field_based(enum bpf_core_relo_kind kind)4659 static bool core_relo_is_field_based(enum bpf_core_relo_kind kind)
4660 {
4661 switch (kind) {
4662 case BPF_FIELD_BYTE_OFFSET:
4663 case BPF_FIELD_BYTE_SIZE:
4664 case BPF_FIELD_EXISTS:
4665 case BPF_FIELD_SIGNED:
4666 case BPF_FIELD_LSHIFT_U64:
4667 case BPF_FIELD_RSHIFT_U64:
4668 return true;
4669 default:
4670 return false;
4671 }
4672 }
4673
core_relo_is_type_based(enum bpf_core_relo_kind kind)4674 static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
4675 {
4676 switch (kind) {
4677 case BPF_TYPE_ID_LOCAL:
4678 case BPF_TYPE_ID_TARGET:
4679 case BPF_TYPE_EXISTS:
4680 case BPF_TYPE_SIZE:
4681 return true;
4682 default:
4683 return false;
4684 }
4685 }
4686
core_relo_is_enumval_based(enum bpf_core_relo_kind kind)4687 static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind)
4688 {
4689 switch (kind) {
4690 case BPF_ENUMVAL_EXISTS:
4691 case BPF_ENUMVAL_VALUE:
4692 return true;
4693 default:
4694 return false;
4695 }
4696 }
4697
4698 /*
4699 * Turn bpf_core_relo into a low- and high-level spec representation,
4700 * validating correctness along the way, as well as calculating resulting
4701 * field bit offset, specified by accessor string. Low-level spec captures
4702 * every single level of nestedness, including traversing anonymous
4703 * struct/union members. High-level one only captures semantically meaningful
4704 * "turning points": named fields and array indicies.
4705 * E.g., for this case:
4706 *
4707 * struct sample {
4708 * int __unimportant;
4709 * struct {
4710 * int __1;
4711 * int __2;
4712 * int a[7];
4713 * };
4714 * };
4715 *
4716 * struct sample *s = ...;
4717 *
4718 * int x = &s->a[3]; // access string = '0:1:2:3'
4719 *
4720 * Low-level spec has 1:1 mapping with each element of access string (it's
4721 * just a parsed access string representation): [0, 1, 2, 3].
4722 *
4723 * High-level spec will capture only 3 points:
4724 * - intial zero-index access by pointer (&s->... is the same as &s[0]...);
4725 * - field 'a' access (corresponds to '2' in low-level spec);
4726 * - array element #3 access (corresponds to '3' in low-level spec).
4727 *
4728 * Type-based relocations (TYPE_EXISTS/TYPE_SIZE,
4729 * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
4730 * spec and raw_spec are kept empty.
4731 *
4732 * Enum value-based relocations (ENUMVAL_EXISTS/ENUMVAL_VALUE) use access
4733 * string to specify enumerator's value index that need to be relocated.
4734 */
bpf_core_parse_spec(const struct btf * btf,__u32 type_id,const char * spec_str,enum bpf_core_relo_kind relo_kind,struct bpf_core_spec * spec)4735 static int bpf_core_parse_spec(const struct btf *btf,
4736 __u32 type_id,
4737 const char *spec_str,
4738 enum bpf_core_relo_kind relo_kind,
4739 struct bpf_core_spec *spec)
4740 {
4741 int access_idx, parsed_len, i;
4742 struct bpf_core_accessor *acc;
4743 const struct btf_type *t;
4744 const char *name;
4745 __u32 id;
4746 __s64 sz;
4747
4748 if (str_is_empty(spec_str) || *spec_str == ':')
4749 return -EINVAL;
4750
4751 memset(spec, 0, sizeof(*spec));
4752 spec->btf = btf;
4753 spec->root_type_id = type_id;
4754 spec->relo_kind = relo_kind;
4755
4756 /* type-based relocations don't have a field access string */
4757 if (core_relo_is_type_based(relo_kind)) {
4758 if (strcmp(spec_str, "0"))
4759 return -EINVAL;
4760 return 0;
4761 }
4762
4763 /* parse spec_str="0:1:2:3:4" into array raw_spec=[0, 1, 2, 3, 4] */
4764 while (*spec_str) {
4765 if (*spec_str == ':')
4766 ++spec_str;
4767 if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1)
4768 return -EINVAL;
4769 if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
4770 return -E2BIG;
4771 spec_str += parsed_len;
4772 spec->raw_spec[spec->raw_len++] = access_idx;
4773 }
4774
4775 if (spec->raw_len == 0)
4776 return -EINVAL;
4777
4778 t = skip_mods_and_typedefs(btf, type_id, &id);
4779 if (!t)
4780 return -EINVAL;
4781
4782 access_idx = spec->raw_spec[0];
4783 acc = &spec->spec[0];
4784 acc->type_id = id;
4785 acc->idx = access_idx;
4786 spec->len++;
4787
4788 if (core_relo_is_enumval_based(relo_kind)) {
4789 if (!btf_is_enum(t) || spec->raw_len > 1 || access_idx >= btf_vlen(t))
4790 return -EINVAL;
4791
4792 /* record enumerator name in a first accessor */
4793 acc->name = btf__name_by_offset(btf, btf_enum(t)[access_idx].name_off);
4794 return 0;
4795 }
4796
4797 if (!core_relo_is_field_based(relo_kind))
4798 return -EINVAL;
4799
4800 sz = btf__resolve_size(btf, id);
4801 if (sz < 0)
4802 return sz;
4803 spec->bit_offset = access_idx * sz * 8;
4804
4805 for (i = 1; i < spec->raw_len; i++) {
4806 t = skip_mods_and_typedefs(btf, id, &id);
4807 if (!t)
4808 return -EINVAL;
4809
4810 access_idx = spec->raw_spec[i];
4811 acc = &spec->spec[spec->len];
4812
4813 if (btf_is_composite(t)) {
4814 const struct btf_member *m;
4815 __u32 bit_offset;
4816
4817 if (access_idx >= btf_vlen(t))
4818 return -EINVAL;
4819
4820 bit_offset = btf_member_bit_offset(t, access_idx);
4821 spec->bit_offset += bit_offset;
4822
4823 m = btf_members(t) + access_idx;
4824 if (m->name_off) {
4825 name = btf__name_by_offset(btf, m->name_off);
4826 if (str_is_empty(name))
4827 return -EINVAL;
4828
4829 acc->type_id = id;
4830 acc->idx = access_idx;
4831 acc->name = name;
4832 spec->len++;
4833 }
4834
4835 id = m->type;
4836 } else if (btf_is_array(t)) {
4837 const struct btf_array *a = btf_array(t);
4838 bool flex;
4839
4840 t = skip_mods_and_typedefs(btf, a->type, &id);
4841 if (!t)
4842 return -EINVAL;
4843
4844 flex = is_flex_arr(btf, acc - 1, a);
4845 if (!flex && access_idx >= a->nelems)
4846 return -EINVAL;
4847
4848 spec->spec[spec->len].type_id = id;
4849 spec->spec[spec->len].idx = access_idx;
4850 spec->len++;
4851
4852 sz = btf__resolve_size(btf, id);
4853 if (sz < 0)
4854 return sz;
4855 spec->bit_offset += access_idx * sz * 8;
4856 } else {
4857 pr_warn("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %s\n",
4858 type_id, spec_str, i, id, btf_kind_str(t));
4859 return -EINVAL;
4860 }
4861 }
4862
4863 return 0;
4864 }
4865
bpf_core_is_flavor_sep(const char * s)4866 static bool bpf_core_is_flavor_sep(const char *s)
4867 {
4868 /* check X___Y name pattern, where X and Y are not underscores */
4869 return s[0] != '_' && /* X */
4870 s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
4871 s[4] != '_'; /* Y */
4872 }
4873
4874 /* Given 'some_struct_name___with_flavor' return the length of a name prefix
4875 * before last triple underscore. Struct name part after last triple
4876 * underscore is ignored by BPF CO-RE relocation during relocation matching.
4877 */
bpf_core_essential_name_len(const char * name)4878 static size_t bpf_core_essential_name_len(const char *name)
4879 {
4880 size_t n = strlen(name);
4881 int i;
4882
4883 for (i = n - 5; i >= 0; i--) {
4884 if (bpf_core_is_flavor_sep(name + i))
4885 return i + 1;
4886 }
4887 return n;
4888 }
4889
4890 struct core_cand
4891 {
4892 const struct btf *btf;
4893 const struct btf_type *t;
4894 const char *name;
4895 __u32 id;
4896 };
4897
4898 /* dynamically sized list of type IDs and its associated struct btf */
4899 struct core_cand_list {
4900 struct core_cand *cands;
4901 int len;
4902 };
4903
bpf_core_free_cands(struct core_cand_list * cands)4904 static void bpf_core_free_cands(struct core_cand_list *cands)
4905 {
4906 free(cands->cands);
4907 free(cands);
4908 }
4909
bpf_core_add_cands(struct core_cand * local_cand,size_t local_essent_len,const struct btf * targ_btf,const char * targ_btf_name,int targ_start_id,struct core_cand_list * cands)4910 static int bpf_core_add_cands(struct core_cand *local_cand,
4911 size_t local_essent_len,
4912 const struct btf *targ_btf,
4913 const char *targ_btf_name,
4914 int targ_start_id,
4915 struct core_cand_list *cands)
4916 {
4917 struct core_cand *new_cands, *cand;
4918 const struct btf_type *t;
4919 const char *targ_name;
4920 size_t targ_essent_len;
4921 int n, i;
4922
4923 n = btf__get_nr_types(targ_btf);
4924 for (i = targ_start_id; i <= n; i++) {
4925 t = btf__type_by_id(targ_btf, i);
4926 if (btf_kind(t) != btf_kind(local_cand->t))
4927 continue;
4928
4929 targ_name = btf__name_by_offset(targ_btf, t->name_off);
4930 if (str_is_empty(targ_name))
4931 continue;
4932
4933 targ_essent_len = bpf_core_essential_name_len(targ_name);
4934 if (targ_essent_len != local_essent_len)
4935 continue;
4936
4937 if (strncmp(local_cand->name, targ_name, local_essent_len) != 0)
4938 continue;
4939
4940 pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s in [%s]\n",
4941 local_cand->id, btf_kind_str(local_cand->t),
4942 local_cand->name, i, btf_kind_str(t), targ_name,
4943 targ_btf_name);
4944 new_cands = libbpf_reallocarray(cands->cands, cands->len + 1,
4945 sizeof(*cands->cands));
4946 if (!new_cands)
4947 return -ENOMEM;
4948
4949 cand = &new_cands[cands->len];
4950 cand->btf = targ_btf;
4951 cand->t = t;
4952 cand->name = targ_name;
4953 cand->id = i;
4954
4955 cands->cands = new_cands;
4956 cands->len++;
4957 }
4958 return 0;
4959 }
4960
load_module_btfs(struct bpf_object * obj)4961 static int load_module_btfs(struct bpf_object *obj)
4962 {
4963 struct bpf_btf_info info;
4964 struct module_btf *mod_btf;
4965 struct btf *btf;
4966 char name[64];
4967 __u32 id = 0, len;
4968 int err, fd;
4969
4970 if (obj->btf_modules_loaded)
4971 return 0;
4972
4973 /* don't do this again, even if we find no module BTFs */
4974 obj->btf_modules_loaded = true;
4975
4976 /* kernel too old to support module BTFs */
4977 if (!kernel_supports(FEAT_MODULE_BTF))
4978 return 0;
4979
4980 while (true) {
4981 err = bpf_btf_get_next_id(id, &id);
4982 if (err && errno == ENOENT)
4983 return 0;
4984 if (err) {
4985 err = -errno;
4986 pr_warn("failed to iterate BTF objects: %d\n", err);
4987 return err;
4988 }
4989
4990 fd = bpf_btf_get_fd_by_id(id);
4991 if (fd < 0) {
4992 if (errno == ENOENT)
4993 continue; /* expected race: BTF was unloaded */
4994 err = -errno;
4995 pr_warn("failed to get BTF object #%d FD: %d\n", id, err);
4996 return err;
4997 }
4998
4999 len = sizeof(info);
5000 memset(&info, 0, sizeof(info));
5001 info.name = ptr_to_u64(name);
5002 info.name_len = sizeof(name);
5003
5004 err = bpf_obj_get_info_by_fd(fd, &info, &len);
5005 if (err) {
5006 err = -errno;
5007 pr_warn("failed to get BTF object #%d info: %d\n", id, err);
5008 goto err_out;
5009 }
5010
5011 /* ignore non-module BTFs */
5012 if (!info.kernel_btf || strcmp(name, "vmlinux") == 0) {
5013 close(fd);
5014 continue;
5015 }
5016
5017 btf = btf_get_from_fd(fd, obj->btf_vmlinux);
5018 if (IS_ERR(btf)) {
5019 pr_warn("failed to load module [%s]'s BTF object #%d: %ld\n",
5020 name, id, PTR_ERR(btf));
5021 err = PTR_ERR(btf);
5022 goto err_out;
5023 }
5024
5025 err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
5026 sizeof(*obj->btf_modules), obj->btf_module_cnt + 1);
5027 if (err)
5028 goto err_out;
5029
5030 mod_btf = &obj->btf_modules[obj->btf_module_cnt++];
5031
5032 mod_btf->btf = btf;
5033 mod_btf->id = id;
5034 mod_btf->fd = fd;
5035 mod_btf->name = strdup(name);
5036 if (!mod_btf->name) {
5037 err = -ENOMEM;
5038 goto err_out;
5039 }
5040 continue;
5041
5042 err_out:
5043 close(fd);
5044 return err;
5045 }
5046
5047 return 0;
5048 }
5049
5050 static struct core_cand_list *
bpf_core_find_cands(struct bpf_object * obj,const struct btf * local_btf,__u32 local_type_id)5051 bpf_core_find_cands(struct bpf_object *obj, const struct btf *local_btf, __u32 local_type_id)
5052 {
5053 struct core_cand local_cand = {};
5054 struct core_cand_list *cands;
5055 const struct btf *main_btf;
5056 size_t local_essent_len;
5057 int err, i;
5058
5059 local_cand.btf = local_btf;
5060 local_cand.t = btf__type_by_id(local_btf, local_type_id);
5061 if (!local_cand.t)
5062 return ERR_PTR(-EINVAL);
5063
5064 local_cand.name = btf__name_by_offset(local_btf, local_cand.t->name_off);
5065 if (str_is_empty(local_cand.name))
5066 return ERR_PTR(-EINVAL);
5067 local_essent_len = bpf_core_essential_name_len(local_cand.name);
5068
5069 cands = calloc(1, sizeof(*cands));
5070 if (!cands)
5071 return ERR_PTR(-ENOMEM);
5072
5073 /* Attempt to find target candidates in vmlinux BTF first */
5074 main_btf = obj->btf_vmlinux_override ?: obj->btf_vmlinux;
5075 err = bpf_core_add_cands(&local_cand, local_essent_len, main_btf, "vmlinux", 1, cands);
5076 if (err)
5077 goto err_out;
5078
5079 /* if vmlinux BTF has any candidate, don't got for module BTFs */
5080 if (cands->len)
5081 return cands;
5082
5083 /* if vmlinux BTF was overridden, don't attempt to load module BTFs */
5084 if (obj->btf_vmlinux_override)
5085 return cands;
5086
5087 /* now look through module BTFs, trying to still find candidates */
5088 err = load_module_btfs(obj);
5089 if (err)
5090 goto err_out;
5091
5092 for (i = 0; i < obj->btf_module_cnt; i++) {
5093 err = bpf_core_add_cands(&local_cand, local_essent_len,
5094 obj->btf_modules[i].btf,
5095 obj->btf_modules[i].name,
5096 btf__get_nr_types(obj->btf_vmlinux) + 1,
5097 cands);
5098 if (err)
5099 goto err_out;
5100 }
5101
5102 return cands;
5103 err_out:
5104 bpf_core_free_cands(cands);
5105 return ERR_PTR(err);
5106 }
5107
5108 /* Check two types for compatibility for the purpose of field access
5109 * relocation. const/volatile/restrict and typedefs are skipped to ensure we
5110 * are relocating semantically compatible entities:
5111 * - any two STRUCTs/UNIONs are compatible and can be mixed;
5112 * - any two FWDs are compatible, if their names match (modulo flavor suffix);
5113 * - any two PTRs are always compatible;
5114 * - for ENUMs, names should be the same (ignoring flavor suffix) or at
5115 * least one of enums should be anonymous;
5116 * - for ENUMs, check sizes, names are ignored;
5117 * - for INT, size and signedness are ignored;
5118 * - any two FLOATs are always compatible;
5119 * - for ARRAY, dimensionality is ignored, element types are checked for
5120 * compatibility recursively;
5121 * - everything else shouldn't be ever a target of relocation.
5122 * These rules are not set in stone and probably will be adjusted as we get
5123 * more experience with using BPF CO-RE relocations.
5124 */
bpf_core_fields_are_compat(const struct btf * local_btf,__u32 local_id,const struct btf * targ_btf,__u32 targ_id)5125 static int bpf_core_fields_are_compat(const struct btf *local_btf,
5126 __u32 local_id,
5127 const struct btf *targ_btf,
5128 __u32 targ_id)
5129 {
5130 const struct btf_type *local_type, *targ_type;
5131
5132 recur:
5133 local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
5134 targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
5135 if (!local_type || !targ_type)
5136 return -EINVAL;
5137
5138 if (btf_is_composite(local_type) && btf_is_composite(targ_type))
5139 return 1;
5140 if (btf_kind(local_type) != btf_kind(targ_type))
5141 return 0;
5142
5143 switch (btf_kind(local_type)) {
5144 case BTF_KIND_PTR:
5145 case BTF_KIND_FLOAT:
5146 return 1;
5147 case BTF_KIND_FWD:
5148 case BTF_KIND_ENUM: {
5149 const char *local_name, *targ_name;
5150 size_t local_len, targ_len;
5151
5152 local_name = btf__name_by_offset(local_btf,
5153 local_type->name_off);
5154 targ_name = btf__name_by_offset(targ_btf, targ_type->name_off);
5155 local_len = bpf_core_essential_name_len(local_name);
5156 targ_len = bpf_core_essential_name_len(targ_name);
5157 /* one of them is anonymous or both w/ same flavor-less names */
5158 return local_len == 0 || targ_len == 0 ||
5159 (local_len == targ_len &&
5160 strncmp(local_name, targ_name, local_len) == 0);
5161 }
5162 case BTF_KIND_INT:
5163 /* just reject deprecated bitfield-like integers; all other
5164 * integers are by default compatible between each other
5165 */
5166 return btf_int_offset(local_type) == 0 &&
5167 btf_int_offset(targ_type) == 0;
5168 case BTF_KIND_ARRAY:
5169 local_id = btf_array(local_type)->type;
5170 targ_id = btf_array(targ_type)->type;
5171 goto recur;
5172 default:
5173 pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
5174 btf_kind(local_type), local_id, targ_id);
5175 return 0;
5176 }
5177 }
5178
5179 /*
5180 * Given single high-level named field accessor in local type, find
5181 * corresponding high-level accessor for a target type. Along the way,
5182 * maintain low-level spec for target as well. Also keep updating target
5183 * bit offset.
5184 *
5185 * Searching is performed through recursive exhaustive enumeration of all
5186 * fields of a struct/union. If there are any anonymous (embedded)
5187 * structs/unions, they are recursively searched as well. If field with
5188 * desired name is found, check compatibility between local and target types,
5189 * before returning result.
5190 *
5191 * 1 is returned, if field is found.
5192 * 0 is returned if no compatible field is found.
5193 * <0 is returned on error.
5194 */
bpf_core_match_member(const struct btf * local_btf,const struct bpf_core_accessor * local_acc,const struct btf * targ_btf,__u32 targ_id,struct bpf_core_spec * spec,__u32 * next_targ_id)5195 static int bpf_core_match_member(const struct btf *local_btf,
5196 const struct bpf_core_accessor *local_acc,
5197 const struct btf *targ_btf,
5198 __u32 targ_id,
5199 struct bpf_core_spec *spec,
5200 __u32 *next_targ_id)
5201 {
5202 const struct btf_type *local_type, *targ_type;
5203 const struct btf_member *local_member, *m;
5204 const char *local_name, *targ_name;
5205 __u32 local_id;
5206 int i, n, found;
5207
5208 targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
5209 if (!targ_type)
5210 return -EINVAL;
5211 if (!btf_is_composite(targ_type))
5212 return 0;
5213
5214 local_id = local_acc->type_id;
5215 local_type = btf__type_by_id(local_btf, local_id);
5216 local_member = btf_members(local_type) + local_acc->idx;
5217 local_name = btf__name_by_offset(local_btf, local_member->name_off);
5218
5219 n = btf_vlen(targ_type);
5220 m = btf_members(targ_type);
5221 for (i = 0; i < n; i++, m++) {
5222 __u32 bit_offset;
5223
5224 bit_offset = btf_member_bit_offset(targ_type, i);
5225
5226 /* too deep struct/union/array nesting */
5227 if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
5228 return -E2BIG;
5229
5230 /* speculate this member will be the good one */
5231 spec->bit_offset += bit_offset;
5232 spec->raw_spec[spec->raw_len++] = i;
5233
5234 targ_name = btf__name_by_offset(targ_btf, m->name_off);
5235 if (str_is_empty(targ_name)) {
5236 /* embedded struct/union, we need to go deeper */
5237 found = bpf_core_match_member(local_btf, local_acc,
5238 targ_btf, m->type,
5239 spec, next_targ_id);
5240 if (found) /* either found or error */
5241 return found;
5242 } else if (strcmp(local_name, targ_name) == 0) {
5243 /* matching named field */
5244 struct bpf_core_accessor *targ_acc;
5245
5246 targ_acc = &spec->spec[spec->len++];
5247 targ_acc->type_id = targ_id;
5248 targ_acc->idx = i;
5249 targ_acc->name = targ_name;
5250
5251 *next_targ_id = m->type;
5252 found = bpf_core_fields_are_compat(local_btf,
5253 local_member->type,
5254 targ_btf, m->type);
5255 if (!found)
5256 spec->len--; /* pop accessor */
5257 return found;
5258 }
5259 /* member turned out not to be what we looked for */
5260 spec->bit_offset -= bit_offset;
5261 spec->raw_len--;
5262 }
5263
5264 return 0;
5265 }
5266
5267 /* Check local and target types for compatibility. This check is used for
5268 * type-based CO-RE relocations and follow slightly different rules than
5269 * field-based relocations. This function assumes that root types were already
5270 * checked for name match. Beyond that initial root-level name check, names
5271 * are completely ignored. Compatibility rules are as follows:
5272 * - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs are considered compatible, but
5273 * kind should match for local and target types (i.e., STRUCT is not
5274 * compatible with UNION);
5275 * - for ENUMs, the size is ignored;
5276 * - for INT, size and signedness are ignored;
5277 * - for ARRAY, dimensionality is ignored, element types are checked for
5278 * compatibility recursively;
5279 * - CONST/VOLATILE/RESTRICT modifiers are ignored;
5280 * - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
5281 * - FUNC_PROTOs are compatible if they have compatible signature: same
5282 * number of input args and compatible return and argument types.
5283 * These rules are not set in stone and probably will be adjusted as we get
5284 * more experience with using BPF CO-RE relocations.
5285 */
bpf_core_types_are_compat(const struct btf * local_btf,__u32 local_id,const struct btf * targ_btf,__u32 targ_id)5286 static int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
5287 const struct btf *targ_btf, __u32 targ_id)
5288 {
5289 const struct btf_type *local_type, *targ_type;
5290 int depth = 32; /* max recursion depth */
5291
5292 /* caller made sure that names match (ignoring flavor suffix) */
5293 local_type = btf__type_by_id(local_btf, local_id);
5294 targ_type = btf__type_by_id(targ_btf, targ_id);
5295 if (btf_kind(local_type) != btf_kind(targ_type))
5296 return 0;
5297
5298 recur:
5299 depth--;
5300 if (depth < 0)
5301 return -EINVAL;
5302
5303 local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
5304 targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
5305 if (!local_type || !targ_type)
5306 return -EINVAL;
5307
5308 if (btf_kind(local_type) != btf_kind(targ_type))
5309 return 0;
5310
5311 switch (btf_kind(local_type)) {
5312 case BTF_KIND_UNKN:
5313 case BTF_KIND_STRUCT:
5314 case BTF_KIND_UNION:
5315 case BTF_KIND_ENUM:
5316 case BTF_KIND_FWD:
5317 return 1;
5318 case BTF_KIND_INT:
5319 /* just reject deprecated bitfield-like integers; all other
5320 * integers are by default compatible between each other
5321 */
5322 return btf_int_offset(local_type) == 0 && btf_int_offset(targ_type) == 0;
5323 case BTF_KIND_PTR:
5324 local_id = local_type->type;
5325 targ_id = targ_type->type;
5326 goto recur;
5327 case BTF_KIND_ARRAY:
5328 local_id = btf_array(local_type)->type;
5329 targ_id = btf_array(targ_type)->type;
5330 goto recur;
5331 case BTF_KIND_FUNC_PROTO: {
5332 struct btf_param *local_p = btf_params(local_type);
5333 struct btf_param *targ_p = btf_params(targ_type);
5334 __u16 local_vlen = btf_vlen(local_type);
5335 __u16 targ_vlen = btf_vlen(targ_type);
5336 int i, err;
5337
5338 if (local_vlen != targ_vlen)
5339 return 0;
5340
5341 for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
5342 skip_mods_and_typedefs(local_btf, local_p->type, &local_id);
5343 skip_mods_and_typedefs(targ_btf, targ_p->type, &targ_id);
5344 err = bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id);
5345 if (err <= 0)
5346 return err;
5347 }
5348
5349 /* tail recurse for return type check */
5350 skip_mods_and_typedefs(local_btf, local_type->type, &local_id);
5351 skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
5352 goto recur;
5353 }
5354 default:
5355 pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
5356 btf_kind_str(local_type), local_id, targ_id);
5357 return 0;
5358 }
5359 }
5360
5361 /*
5362 * Try to match local spec to a target type and, if successful, produce full
5363 * target spec (high-level, low-level + bit offset).
5364 */
bpf_core_spec_match(struct bpf_core_spec * local_spec,const struct btf * targ_btf,__u32 targ_id,struct bpf_core_spec * targ_spec)5365 static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
5366 const struct btf *targ_btf, __u32 targ_id,
5367 struct bpf_core_spec *targ_spec)
5368 {
5369 const struct btf_type *targ_type;
5370 const struct bpf_core_accessor *local_acc;
5371 struct bpf_core_accessor *targ_acc;
5372 int i, sz, matched;
5373
5374 memset(targ_spec, 0, sizeof(*targ_spec));
5375 targ_spec->btf = targ_btf;
5376 targ_spec->root_type_id = targ_id;
5377 targ_spec->relo_kind = local_spec->relo_kind;
5378
5379 if (core_relo_is_type_based(local_spec->relo_kind)) {
5380 return bpf_core_types_are_compat(local_spec->btf,
5381 local_spec->root_type_id,
5382 targ_btf, targ_id);
5383 }
5384
5385 local_acc = &local_spec->spec[0];
5386 targ_acc = &targ_spec->spec[0];
5387
5388 if (core_relo_is_enumval_based(local_spec->relo_kind)) {
5389 size_t local_essent_len, targ_essent_len;
5390 const struct btf_enum *e;
5391 const char *targ_name;
5392
5393 /* has to resolve to an enum */
5394 targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id, &targ_id);
5395 if (!btf_is_enum(targ_type))
5396 return 0;
5397
5398 local_essent_len = bpf_core_essential_name_len(local_acc->name);
5399
5400 for (i = 0, e = btf_enum(targ_type); i < btf_vlen(targ_type); i++, e++) {
5401 targ_name = btf__name_by_offset(targ_spec->btf, e->name_off);
5402 targ_essent_len = bpf_core_essential_name_len(targ_name);
5403 if (targ_essent_len != local_essent_len)
5404 continue;
5405 if (strncmp(local_acc->name, targ_name, local_essent_len) == 0) {
5406 targ_acc->type_id = targ_id;
5407 targ_acc->idx = i;
5408 targ_acc->name = targ_name;
5409 targ_spec->len++;
5410 targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
5411 targ_spec->raw_len++;
5412 return 1;
5413 }
5414 }
5415 return 0;
5416 }
5417
5418 if (!core_relo_is_field_based(local_spec->relo_kind))
5419 return -EINVAL;
5420
5421 for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) {
5422 targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id,
5423 &targ_id);
5424 if (!targ_type)
5425 return -EINVAL;
5426
5427 if (local_acc->name) {
5428 matched = bpf_core_match_member(local_spec->btf,
5429 local_acc,
5430 targ_btf, targ_id,
5431 targ_spec, &targ_id);
5432 if (matched <= 0)
5433 return matched;
5434 } else {
5435 /* for i=0, targ_id is already treated as array element
5436 * type (because it's the original struct), for others
5437 * we should find array element type first
5438 */
5439 if (i > 0) {
5440 const struct btf_array *a;
5441 bool flex;
5442
5443 if (!btf_is_array(targ_type))
5444 return 0;
5445
5446 a = btf_array(targ_type);
5447 flex = is_flex_arr(targ_btf, targ_acc - 1, a);
5448 if (!flex && local_acc->idx >= a->nelems)
5449 return 0;
5450 if (!skip_mods_and_typedefs(targ_btf, a->type,
5451 &targ_id))
5452 return -EINVAL;
5453 }
5454
5455 /* too deep struct/union/array nesting */
5456 if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
5457 return -E2BIG;
5458
5459 targ_acc->type_id = targ_id;
5460 targ_acc->idx = local_acc->idx;
5461 targ_acc->name = NULL;
5462 targ_spec->len++;
5463 targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
5464 targ_spec->raw_len++;
5465
5466 sz = btf__resolve_size(targ_btf, targ_id);
5467 if (sz < 0)
5468 return sz;
5469 targ_spec->bit_offset += local_acc->idx * sz * 8;
5470 }
5471 }
5472
5473 return 1;
5474 }
5475
bpf_core_calc_field_relo(const struct bpf_program * prog,const struct bpf_core_relo * relo,const struct bpf_core_spec * spec,__u32 * val,__u32 * field_sz,__u32 * type_id,bool * validate)5476 static int bpf_core_calc_field_relo(const struct bpf_program *prog,
5477 const struct bpf_core_relo *relo,
5478 const struct bpf_core_spec *spec,
5479 __u32 *val, __u32 *field_sz, __u32 *type_id,
5480 bool *validate)
5481 {
5482 const struct bpf_core_accessor *acc;
5483 const struct btf_type *t;
5484 __u32 byte_off, byte_sz, bit_off, bit_sz, field_type_id;
5485 const struct btf_member *m;
5486 const struct btf_type *mt;
5487 bool bitfield;
5488 __s64 sz;
5489
5490 *field_sz = 0;
5491
5492 if (relo->kind == BPF_FIELD_EXISTS) {
5493 *val = spec ? 1 : 0;
5494 return 0;
5495 }
5496
5497 if (!spec)
5498 return -EUCLEAN; /* request instruction poisoning */
5499
5500 acc = &spec->spec[spec->len - 1];
5501 t = btf__type_by_id(spec->btf, acc->type_id);
5502
5503 /* a[n] accessor needs special handling */
5504 if (!acc->name) {
5505 if (relo->kind == BPF_FIELD_BYTE_OFFSET) {
5506 *val = spec->bit_offset / 8;
5507 /* remember field size for load/store mem size */
5508 sz = btf__resolve_size(spec->btf, acc->type_id);
5509 if (sz < 0)
5510 return -EINVAL;
5511 *field_sz = sz;
5512 *type_id = acc->type_id;
5513 } else if (relo->kind == BPF_FIELD_BYTE_SIZE) {
5514 sz = btf__resolve_size(spec->btf, acc->type_id);
5515 if (sz < 0)
5516 return -EINVAL;
5517 *val = sz;
5518 } else {
5519 pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n",
5520 prog->name, relo->kind, relo->insn_off / 8);
5521 return -EINVAL;
5522 }
5523 if (validate)
5524 *validate = true;
5525 return 0;
5526 }
5527
5528 m = btf_members(t) + acc->idx;
5529 mt = skip_mods_and_typedefs(spec->btf, m->type, &field_type_id);
5530 bit_off = spec->bit_offset;
5531 bit_sz = btf_member_bitfield_size(t, acc->idx);
5532
5533 bitfield = bit_sz > 0;
5534 if (bitfield) {
5535 byte_sz = mt->size;
5536 byte_off = bit_off / 8 / byte_sz * byte_sz;
5537 /* figure out smallest int size necessary for bitfield load */
5538 while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) {
5539 if (byte_sz >= 8) {
5540 /* bitfield can't be read with 64-bit read */
5541 pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n",
5542 prog->name, relo->kind, relo->insn_off / 8);
5543 return -E2BIG;
5544 }
5545 byte_sz *= 2;
5546 byte_off = bit_off / 8 / byte_sz * byte_sz;
5547 }
5548 } else {
5549 sz = btf__resolve_size(spec->btf, field_type_id);
5550 if (sz < 0)
5551 return -EINVAL;
5552 byte_sz = sz;
5553 byte_off = spec->bit_offset / 8;
5554 bit_sz = byte_sz * 8;
5555 }
5556
5557 /* for bitfields, all the relocatable aspects are ambiguous and we
5558 * might disagree with compiler, so turn off validation of expected
5559 * value, except for signedness
5560 */
5561 if (validate)
5562 *validate = !bitfield;
5563
5564 switch (relo->kind) {
5565 case BPF_FIELD_BYTE_OFFSET:
5566 *val = byte_off;
5567 if (!bitfield) {
5568 *field_sz = byte_sz;
5569 *type_id = field_type_id;
5570 }
5571 break;
5572 case BPF_FIELD_BYTE_SIZE:
5573 *val = byte_sz;
5574 break;
5575 case BPF_FIELD_SIGNED:
5576 /* enums will be assumed unsigned */
5577 *val = btf_is_enum(mt) ||
5578 (btf_int_encoding(mt) & BTF_INT_SIGNED);
5579 if (validate)
5580 *validate = true; /* signedness is never ambiguous */
5581 break;
5582 case BPF_FIELD_LSHIFT_U64:
5583 #if __BYTE_ORDER == __LITTLE_ENDIAN
5584 *val = 64 - (bit_off + bit_sz - byte_off * 8);
5585 #else
5586 *val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8);
5587 #endif
5588 break;
5589 case BPF_FIELD_RSHIFT_U64:
5590 *val = 64 - bit_sz;
5591 if (validate)
5592 *validate = true; /* right shift is never ambiguous */
5593 break;
5594 case BPF_FIELD_EXISTS:
5595 default:
5596 return -EOPNOTSUPP;
5597 }
5598
5599 return 0;
5600 }
5601
bpf_core_calc_type_relo(const struct bpf_core_relo * relo,const struct bpf_core_spec * spec,__u32 * val)5602 static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
5603 const struct bpf_core_spec *spec,
5604 __u32 *val)
5605 {
5606 __s64 sz;
5607
5608 /* type-based relos return zero when target type is not found */
5609 if (!spec) {
5610 *val = 0;
5611 return 0;
5612 }
5613
5614 switch (relo->kind) {
5615 case BPF_TYPE_ID_TARGET:
5616 *val = spec->root_type_id;
5617 break;
5618 case BPF_TYPE_EXISTS:
5619 *val = 1;
5620 break;
5621 case BPF_TYPE_SIZE:
5622 sz = btf__resolve_size(spec->btf, spec->root_type_id);
5623 if (sz < 0)
5624 return -EINVAL;
5625 *val = sz;
5626 break;
5627 case BPF_TYPE_ID_LOCAL:
5628 /* BPF_TYPE_ID_LOCAL is handled specially and shouldn't get here */
5629 default:
5630 return -EOPNOTSUPP;
5631 }
5632
5633 return 0;
5634 }
5635
bpf_core_calc_enumval_relo(const struct bpf_core_relo * relo,const struct bpf_core_spec * spec,__u32 * val)5636 static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo,
5637 const struct bpf_core_spec *spec,
5638 __u32 *val)
5639 {
5640 const struct btf_type *t;
5641 const struct btf_enum *e;
5642
5643 switch (relo->kind) {
5644 case BPF_ENUMVAL_EXISTS:
5645 *val = spec ? 1 : 0;
5646 break;
5647 case BPF_ENUMVAL_VALUE:
5648 if (!spec)
5649 return -EUCLEAN; /* request instruction poisoning */
5650 t = btf__type_by_id(spec->btf, spec->spec[0].type_id);
5651 e = btf_enum(t) + spec->spec[0].idx;
5652 *val = e->val;
5653 break;
5654 default:
5655 return -EOPNOTSUPP;
5656 }
5657
5658 return 0;
5659 }
5660
5661 struct bpf_core_relo_res
5662 {
5663 /* expected value in the instruction, unless validate == false */
5664 __u32 orig_val;
5665 /* new value that needs to be patched up to */
5666 __u32 new_val;
5667 /* relocation unsuccessful, poison instruction, but don't fail load */
5668 bool poison;
5669 /* some relocations can't be validated against orig_val */
5670 bool validate;
5671 /* for field byte offset relocations or the forms:
5672 * *(T *)(rX + <off>) = rY
5673 * rX = *(T *)(rY + <off>),
5674 * we remember original and resolved field size to adjust direct
5675 * memory loads of pointers and integers; this is necessary for 32-bit
5676 * host kernel architectures, but also allows to automatically
5677 * relocate fields that were resized from, e.g., u32 to u64, etc.
5678 */
5679 bool fail_memsz_adjust;
5680 __u32 orig_sz;
5681 __u32 orig_type_id;
5682 __u32 new_sz;
5683 __u32 new_type_id;
5684 };
5685
5686 /* Calculate original and target relocation values, given local and target
5687 * specs and relocation kind. These values are calculated for each candidate.
5688 * If there are multiple candidates, resulting values should all be consistent
5689 * with each other. Otherwise, libbpf will refuse to proceed due to ambiguity.
5690 * If instruction has to be poisoned, *poison will be set to true.
5691 */
bpf_core_calc_relo(const struct bpf_program * prog,const struct bpf_core_relo * relo,int relo_idx,const struct bpf_core_spec * local_spec,const struct bpf_core_spec * targ_spec,struct bpf_core_relo_res * res)5692 static int bpf_core_calc_relo(const struct bpf_program *prog,
5693 const struct bpf_core_relo *relo,
5694 int relo_idx,
5695 const struct bpf_core_spec *local_spec,
5696 const struct bpf_core_spec *targ_spec,
5697 struct bpf_core_relo_res *res)
5698 {
5699 int err = -EOPNOTSUPP;
5700
5701 res->orig_val = 0;
5702 res->new_val = 0;
5703 res->poison = false;
5704 res->validate = true;
5705 res->fail_memsz_adjust = false;
5706 res->orig_sz = res->new_sz = 0;
5707 res->orig_type_id = res->new_type_id = 0;
5708
5709 if (core_relo_is_field_based(relo->kind)) {
5710 err = bpf_core_calc_field_relo(prog, relo, local_spec,
5711 &res->orig_val, &res->orig_sz,
5712 &res->orig_type_id, &res->validate);
5713 err = err ?: bpf_core_calc_field_relo(prog, relo, targ_spec,
5714 &res->new_val, &res->new_sz,
5715 &res->new_type_id, NULL);
5716 if (err)
5717 goto done;
5718 /* Validate if it's safe to adjust load/store memory size.
5719 * Adjustments are performed only if original and new memory
5720 * sizes differ.
5721 */
5722 res->fail_memsz_adjust = false;
5723 if (res->orig_sz != res->new_sz) {
5724 const struct btf_type *orig_t, *new_t;
5725
5726 orig_t = btf__type_by_id(local_spec->btf, res->orig_type_id);
5727 new_t = btf__type_by_id(targ_spec->btf, res->new_type_id);
5728
5729 /* There are two use cases in which it's safe to
5730 * adjust load/store's mem size:
5731 * - reading a 32-bit kernel pointer, while on BPF
5732 * size pointers are always 64-bit; in this case
5733 * it's safe to "downsize" instruction size due to
5734 * pointer being treated as unsigned integer with
5735 * zero-extended upper 32-bits;
5736 * - reading unsigned integers, again due to
5737 * zero-extension is preserving the value correctly.
5738 *
5739 * In all other cases it's incorrect to attempt to
5740 * load/store field because read value will be
5741 * incorrect, so we poison relocated instruction.
5742 */
5743 if (btf_is_ptr(orig_t) && btf_is_ptr(new_t))
5744 goto done;
5745 if (btf_is_int(orig_t) && btf_is_int(new_t) &&
5746 btf_int_encoding(orig_t) != BTF_INT_SIGNED &&
5747 btf_int_encoding(new_t) != BTF_INT_SIGNED)
5748 goto done;
5749
5750 /* mark as invalid mem size adjustment, but this will
5751 * only be checked for LDX/STX/ST insns
5752 */
5753 res->fail_memsz_adjust = true;
5754 }
5755 } else if (core_relo_is_type_based(relo->kind)) {
5756 err = bpf_core_calc_type_relo(relo, local_spec, &res->orig_val);
5757 err = err ?: bpf_core_calc_type_relo(relo, targ_spec, &res->new_val);
5758 } else if (core_relo_is_enumval_based(relo->kind)) {
5759 err = bpf_core_calc_enumval_relo(relo, local_spec, &res->orig_val);
5760 err = err ?: bpf_core_calc_enumval_relo(relo, targ_spec, &res->new_val);
5761 }
5762
5763 done:
5764 if (err == -EUCLEAN) {
5765 /* EUCLEAN is used to signal instruction poisoning request */
5766 res->poison = true;
5767 err = 0;
5768 } else if (err == -EOPNOTSUPP) {
5769 /* EOPNOTSUPP means unknown/unsupported relocation */
5770 pr_warn("prog '%s': relo #%d: unrecognized CO-RE relocation %s (%d) at insn #%d\n",
5771 prog->name, relo_idx, core_relo_kind_str(relo->kind),
5772 relo->kind, relo->insn_off / 8);
5773 }
5774
5775 return err;
5776 }
5777
5778 /*
5779 * Turn instruction for which CO_RE relocation failed into invalid one with
5780 * distinct signature.
5781 */
bpf_core_poison_insn(struct bpf_program * prog,int relo_idx,int insn_idx,struct bpf_insn * insn)5782 static void bpf_core_poison_insn(struct bpf_program *prog, int relo_idx,
5783 int insn_idx, struct bpf_insn *insn)
5784 {
5785 pr_debug("prog '%s': relo #%d: substituting insn #%d w/ invalid insn\n",
5786 prog->name, relo_idx, insn_idx);
5787 insn->code = BPF_JMP | BPF_CALL;
5788 insn->dst_reg = 0;
5789 insn->src_reg = 0;
5790 insn->off = 0;
5791 /* if this instruction is reachable (not a dead code),
5792 * verifier will complain with the following message:
5793 * invalid func unknown#195896080
5794 */
5795 insn->imm = 195896080; /* => 0xbad2310 => "bad relo" */
5796 }
5797
insn_bpf_size_to_bytes(struct bpf_insn * insn)5798 static int insn_bpf_size_to_bytes(struct bpf_insn *insn)
5799 {
5800 switch (BPF_SIZE(insn->code)) {
5801 case BPF_DW: return 8;
5802 case BPF_W: return 4;
5803 case BPF_H: return 2;
5804 case BPF_B: return 1;
5805 default: return -1;
5806 }
5807 }
5808
insn_bytes_to_bpf_size(__u32 sz)5809 static int insn_bytes_to_bpf_size(__u32 sz)
5810 {
5811 switch (sz) {
5812 case 8: return BPF_DW;
5813 case 4: return BPF_W;
5814 case 2: return BPF_H;
5815 case 1: return BPF_B;
5816 default: return -1;
5817 }
5818 }
5819
5820 /*
5821 * Patch relocatable BPF instruction.
5822 *
5823 * Patched value is determined by relocation kind and target specification.
5824 * For existence relocations target spec will be NULL if field/type is not found.
5825 * Expected insn->imm value is determined using relocation kind and local
5826 * spec, and is checked before patching instruction. If actual insn->imm value
5827 * is wrong, bail out with error.
5828 *
5829 * Currently supported classes of BPF instruction are:
5830 * 1. rX = <imm> (assignment with immediate operand);
5831 * 2. rX += <imm> (arithmetic operations with immediate operand);
5832 * 3. rX = <imm64> (load with 64-bit immediate value);
5833 * 4. rX = *(T *)(rY + <off>), where T is one of {u8, u16, u32, u64};
5834 * 5. *(T *)(rX + <off>) = rY, where T is one of {u8, u16, u32, u64};
5835 * 6. *(T *)(rX + <off>) = <imm>, where T is one of {u8, u16, u32, u64}.
5836 */
bpf_core_patch_insn(struct bpf_program * prog,const struct bpf_core_relo * relo,int relo_idx,const struct bpf_core_relo_res * res)5837 static int bpf_core_patch_insn(struct bpf_program *prog,
5838 const struct bpf_core_relo *relo,
5839 int relo_idx,
5840 const struct bpf_core_relo_res *res)
5841 {
5842 __u32 orig_val, new_val;
5843 struct bpf_insn *insn;
5844 int insn_idx;
5845 __u8 class;
5846
5847 if (relo->insn_off % BPF_INSN_SZ)
5848 return -EINVAL;
5849 insn_idx = relo->insn_off / BPF_INSN_SZ;
5850 /* adjust insn_idx from section frame of reference to the local
5851 * program's frame of reference; (sub-)program code is not yet
5852 * relocated, so it's enough to just subtract in-section offset
5853 */
5854 insn_idx = insn_idx - prog->sec_insn_off;
5855 insn = &prog->insns[insn_idx];
5856 class = BPF_CLASS(insn->code);
5857
5858 if (res->poison) {
5859 poison:
5860 /* poison second part of ldimm64 to avoid confusing error from
5861 * verifier about "unknown opcode 00"
5862 */
5863 if (is_ldimm64_insn(insn))
5864 bpf_core_poison_insn(prog, relo_idx, insn_idx + 1, insn + 1);
5865 bpf_core_poison_insn(prog, relo_idx, insn_idx, insn);
5866 return 0;
5867 }
5868
5869 orig_val = res->orig_val;
5870 new_val = res->new_val;
5871
5872 switch (class) {
5873 case BPF_ALU:
5874 case BPF_ALU64:
5875 if (BPF_SRC(insn->code) != BPF_K)
5876 return -EINVAL;
5877 if (res->validate && insn->imm != orig_val) {
5878 pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %u -> %u\n",
5879 prog->name, relo_idx,
5880 insn_idx, insn->imm, orig_val, new_val);
5881 return -EINVAL;
5882 }
5883 orig_val = insn->imm;
5884 insn->imm = new_val;
5885 pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %u -> %u\n",
5886 prog->name, relo_idx, insn_idx,
5887 orig_val, new_val);
5888 break;
5889 case BPF_LDX:
5890 case BPF_ST:
5891 case BPF_STX:
5892 if (res->validate && insn->off != orig_val) {
5893 pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %u -> %u\n",
5894 prog->name, relo_idx, insn_idx, insn->off, orig_val, new_val);
5895 return -EINVAL;
5896 }
5897 if (new_val > SHRT_MAX) {
5898 pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %u\n",
5899 prog->name, relo_idx, insn_idx, new_val);
5900 return -ERANGE;
5901 }
5902 if (res->fail_memsz_adjust) {
5903 pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) accesses field incorrectly. "
5904 "Make sure you are accessing pointers, unsigned integers, or fields of matching type and size.\n",
5905 prog->name, relo_idx, insn_idx);
5906 goto poison;
5907 }
5908
5909 orig_val = insn->off;
5910 insn->off = new_val;
5911 pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %u -> %u\n",
5912 prog->name, relo_idx, insn_idx, orig_val, new_val);
5913
5914 if (res->new_sz != res->orig_sz) {
5915 int insn_bytes_sz, insn_bpf_sz;
5916
5917 insn_bytes_sz = insn_bpf_size_to_bytes(insn);
5918 if (insn_bytes_sz != res->orig_sz) {
5919 pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) unexpected mem size: got %d, exp %u\n",
5920 prog->name, relo_idx, insn_idx, insn_bytes_sz, res->orig_sz);
5921 return -EINVAL;
5922 }
5923
5924 insn_bpf_sz = insn_bytes_to_bpf_size(res->new_sz);
5925 if (insn_bpf_sz < 0) {
5926 pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) invalid new mem size: %u\n",
5927 prog->name, relo_idx, insn_idx, res->new_sz);
5928 return -EINVAL;
5929 }
5930
5931 insn->code = BPF_MODE(insn->code) | insn_bpf_sz | BPF_CLASS(insn->code);
5932 pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) mem_sz %u -> %u\n",
5933 prog->name, relo_idx, insn_idx, res->orig_sz, res->new_sz);
5934 }
5935 break;
5936 case BPF_LD: {
5937 __u64 imm;
5938
5939 if (!is_ldimm64_insn(insn) ||
5940 insn[0].src_reg != 0 || insn[0].off != 0 ||
5941 insn_idx + 1 >= prog->insns_cnt ||
5942 insn[1].code != 0 || insn[1].dst_reg != 0 ||
5943 insn[1].src_reg != 0 || insn[1].off != 0) {
5944 pr_warn("prog '%s': relo #%d: insn #%d (LDIMM64) has unexpected form\n",
5945 prog->name, relo_idx, insn_idx);
5946 return -EINVAL;
5947 }
5948
5949 imm = insn[0].imm + ((__u64)insn[1].imm << 32);
5950 if (res->validate && imm != orig_val) {
5951 pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n",
5952 prog->name, relo_idx,
5953 insn_idx, (unsigned long long)imm,
5954 orig_val, new_val);
5955 return -EINVAL;
5956 }
5957
5958 insn[0].imm = new_val;
5959 insn[1].imm = 0; /* currently only 32-bit values are supported */
5960 pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n",
5961 prog->name, relo_idx, insn_idx,
5962 (unsigned long long)imm, new_val);
5963 break;
5964 }
5965 default:
5966 pr_warn("prog '%s': relo #%d: trying to relocate unrecognized insn #%d, code:0x%x, src:0x%x, dst:0x%x, off:0x%x, imm:0x%x\n",
5967 prog->name, relo_idx, insn_idx, insn->code,
5968 insn->src_reg, insn->dst_reg, insn->off, insn->imm);
5969 return -EINVAL;
5970 }
5971
5972 return 0;
5973 }
5974
5975 /* Output spec definition in the format:
5976 * [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
5977 * where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
5978 */
bpf_core_dump_spec(int level,const struct bpf_core_spec * spec)5979 static void bpf_core_dump_spec(int level, const struct bpf_core_spec *spec)
5980 {
5981 const struct btf_type *t;
5982 const struct btf_enum *e;
5983 const char *s;
5984 __u32 type_id;
5985 int i;
5986
5987 type_id = spec->root_type_id;
5988 t = btf__type_by_id(spec->btf, type_id);
5989 s = btf__name_by_offset(spec->btf, t->name_off);
5990
5991 libbpf_print(level, "[%u] %s %s", type_id, btf_kind_str(t), str_is_empty(s) ? "<anon>" : s);
5992
5993 if (core_relo_is_type_based(spec->relo_kind))
5994 return;
5995
5996 if (core_relo_is_enumval_based(spec->relo_kind)) {
5997 t = skip_mods_and_typedefs(spec->btf, type_id, NULL);
5998 e = btf_enum(t) + spec->raw_spec[0];
5999 s = btf__name_by_offset(spec->btf, e->name_off);
6000
6001 libbpf_print(level, "::%s = %u", s, e->val);
6002 return;
6003 }
6004
6005 if (core_relo_is_field_based(spec->relo_kind)) {
6006 for (i = 0; i < spec->len; i++) {
6007 if (spec->spec[i].name)
6008 libbpf_print(level, ".%s", spec->spec[i].name);
6009 else if (i > 0 || spec->spec[i].idx > 0)
6010 libbpf_print(level, "[%u]", spec->spec[i].idx);
6011 }
6012
6013 libbpf_print(level, " (");
6014 for (i = 0; i < spec->raw_len; i++)
6015 libbpf_print(level, "%s%d", i == 0 ? "" : ":", spec->raw_spec[i]);
6016
6017 if (spec->bit_offset % 8)
6018 libbpf_print(level, " @ offset %u.%u)",
6019 spec->bit_offset / 8, spec->bit_offset % 8);
6020 else
6021 libbpf_print(level, " @ offset %u)", spec->bit_offset / 8);
6022 return;
6023 }
6024 }
6025
bpf_core_hash_fn(const void * key,void * ctx)6026 static size_t bpf_core_hash_fn(const void *key, void *ctx)
6027 {
6028 return (size_t)key;
6029 }
6030
bpf_core_equal_fn(const void * k1,const void * k2,void * ctx)6031 static bool bpf_core_equal_fn(const void *k1, const void *k2, void *ctx)
6032 {
6033 return k1 == k2;
6034 }
6035
u32_as_hash_key(__u32 x)6036 static void *u32_as_hash_key(__u32 x)
6037 {
6038 return (void *)(uintptr_t)x;
6039 }
6040
6041 /*
6042 * CO-RE relocate single instruction.
6043 *
6044 * The outline and important points of the algorithm:
6045 * 1. For given local type, find corresponding candidate target types.
6046 * Candidate type is a type with the same "essential" name, ignoring
6047 * everything after last triple underscore (___). E.g., `sample`,
6048 * `sample___flavor_one`, `sample___flavor_another_one`, are all candidates
6049 * for each other. Names with triple underscore are referred to as
6050 * "flavors" and are useful, among other things, to allow to
6051 * specify/support incompatible variations of the same kernel struct, which
6052 * might differ between different kernel versions and/or build
6053 * configurations.
6054 *
6055 * N.B. Struct "flavors" could be generated by bpftool's BTF-to-C
6056 * converter, when deduplicated BTF of a kernel still contains more than
6057 * one different types with the same name. In that case, ___2, ___3, etc
6058 * are appended starting from second name conflict. But start flavors are
6059 * also useful to be defined "locally", in BPF program, to extract same
6060 * data from incompatible changes between different kernel
6061 * versions/configurations. For instance, to handle field renames between
6062 * kernel versions, one can use two flavors of the struct name with the
6063 * same common name and use conditional relocations to extract that field,
6064 * depending on target kernel version.
6065 * 2. For each candidate type, try to match local specification to this
6066 * candidate target type. Matching involves finding corresponding
6067 * high-level spec accessors, meaning that all named fields should match,
6068 * as well as all array accesses should be within the actual bounds. Also,
6069 * types should be compatible (see bpf_core_fields_are_compat for details).
6070 * 3. It is supported and expected that there might be multiple flavors
6071 * matching the spec. As long as all the specs resolve to the same set of
6072 * offsets across all candidates, there is no error. If there is any
6073 * ambiguity, CO-RE relocation will fail. This is necessary to accomodate
6074 * imprefection of BTF deduplication, which can cause slight duplication of
6075 * the same BTF type, if some directly or indirectly referenced (by
6076 * pointer) type gets resolved to different actual types in different
6077 * object files. If such situation occurs, deduplicated BTF will end up
6078 * with two (or more) structurally identical types, which differ only in
6079 * types they refer to through pointer. This should be OK in most cases and
6080 * is not an error.
6081 * 4. Candidate types search is performed by linearly scanning through all
6082 * types in target BTF. It is anticipated that this is overall more
6083 * efficient memory-wise and not significantly worse (if not better)
6084 * CPU-wise compared to prebuilding a map from all local type names to
6085 * a list of candidate type names. It's also sped up by caching resolved
6086 * list of matching candidates per each local "root" type ID, that has at
6087 * least one bpf_core_relo associated with it. This list is shared
6088 * between multiple relocations for the same type ID and is updated as some
6089 * of the candidates are pruned due to structural incompatibility.
6090 */
bpf_core_apply_relo(struct bpf_program * prog,const struct bpf_core_relo * relo,int relo_idx,const struct btf * local_btf,struct hashmap * cand_cache)6091 static int bpf_core_apply_relo(struct bpf_program *prog,
6092 const struct bpf_core_relo *relo,
6093 int relo_idx,
6094 const struct btf *local_btf,
6095 struct hashmap *cand_cache)
6096 {
6097 struct bpf_core_spec local_spec, cand_spec, targ_spec = {};
6098 const void *type_key = u32_as_hash_key(relo->type_id);
6099 struct bpf_core_relo_res cand_res, targ_res;
6100 const struct btf_type *local_type;
6101 const char *local_name;
6102 struct core_cand_list *cands = NULL;
6103 __u32 local_id;
6104 const char *spec_str;
6105 int i, j, err;
6106
6107 local_id = relo->type_id;
6108 local_type = btf__type_by_id(local_btf, local_id);
6109 if (!local_type)
6110 return -EINVAL;
6111
6112 local_name = btf__name_by_offset(local_btf, local_type->name_off);
6113 if (!local_name)
6114 return -EINVAL;
6115
6116 spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
6117 if (str_is_empty(spec_str))
6118 return -EINVAL;
6119
6120 err = bpf_core_parse_spec(local_btf, local_id, spec_str, relo->kind, &local_spec);
6121 if (err) {
6122 pr_warn("prog '%s': relo #%d: parsing [%d] %s %s + %s failed: %d\n",
6123 prog->name, relo_idx, local_id, btf_kind_str(local_type),
6124 str_is_empty(local_name) ? "<anon>" : local_name,
6125 spec_str, err);
6126 return -EINVAL;
6127 }
6128
6129 pr_debug("prog '%s': relo #%d: kind <%s> (%d), spec is ", prog->name,
6130 relo_idx, core_relo_kind_str(relo->kind), relo->kind);
6131 bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec);
6132 libbpf_print(LIBBPF_DEBUG, "\n");
6133
6134 /* TYPE_ID_LOCAL relo is special and doesn't need candidate search */
6135 if (relo->kind == BPF_TYPE_ID_LOCAL) {
6136 targ_res.validate = true;
6137 targ_res.poison = false;
6138 targ_res.orig_val = local_spec.root_type_id;
6139 targ_res.new_val = local_spec.root_type_id;
6140 goto patch_insn;
6141 }
6142
6143 /* libbpf doesn't support candidate search for anonymous types */
6144 if (str_is_empty(spec_str)) {
6145 pr_warn("prog '%s': relo #%d: <%s> (%d) relocation doesn't support anonymous types\n",
6146 prog->name, relo_idx, core_relo_kind_str(relo->kind), relo->kind);
6147 return -EOPNOTSUPP;
6148 }
6149
6150 if (!hashmap__find(cand_cache, type_key, (void **)&cands)) {
6151 cands = bpf_core_find_cands(prog->obj, local_btf, local_id);
6152 if (IS_ERR(cands)) {
6153 pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s %s: %ld\n",
6154 prog->name, relo_idx, local_id, btf_kind_str(local_type),
6155 local_name, PTR_ERR(cands));
6156 return PTR_ERR(cands);
6157 }
6158 err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
6159 if (err) {
6160 bpf_core_free_cands(cands);
6161 return err;
6162 }
6163 }
6164
6165 for (i = 0, j = 0; i < cands->len; i++) {
6166 err = bpf_core_spec_match(&local_spec, cands->cands[i].btf,
6167 cands->cands[i].id, &cand_spec);
6168 if (err < 0) {
6169 pr_warn("prog '%s': relo #%d: error matching candidate #%d ",
6170 prog->name, relo_idx, i);
6171 bpf_core_dump_spec(LIBBPF_WARN, &cand_spec);
6172 libbpf_print(LIBBPF_WARN, ": %d\n", err);
6173 return err;
6174 }
6175
6176 pr_debug("prog '%s': relo #%d: %s candidate #%d ", prog->name,
6177 relo_idx, err == 0 ? "non-matching" : "matching", i);
6178 bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
6179 libbpf_print(LIBBPF_DEBUG, "\n");
6180
6181 if (err == 0)
6182 continue;
6183
6184 err = bpf_core_calc_relo(prog, relo, relo_idx, &local_spec, &cand_spec, &cand_res);
6185 if (err)
6186 return err;
6187
6188 if (j == 0) {
6189 targ_res = cand_res;
6190 targ_spec = cand_spec;
6191 } else if (cand_spec.bit_offset != targ_spec.bit_offset) {
6192 /* if there are many field relo candidates, they
6193 * should all resolve to the same bit offset
6194 */
6195 pr_warn("prog '%s': relo #%d: field offset ambiguity: %u != %u\n",
6196 prog->name, relo_idx, cand_spec.bit_offset,
6197 targ_spec.bit_offset);
6198 return -EINVAL;
6199 } else if (cand_res.poison != targ_res.poison || cand_res.new_val != targ_res.new_val) {
6200 /* all candidates should result in the same relocation
6201 * decision and value, otherwise it's dangerous to
6202 * proceed due to ambiguity
6203 */
6204 pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %u != %s %u\n",
6205 prog->name, relo_idx,
6206 cand_res.poison ? "failure" : "success", cand_res.new_val,
6207 targ_res.poison ? "failure" : "success", targ_res.new_val);
6208 return -EINVAL;
6209 }
6210
6211 cands->cands[j++] = cands->cands[i];
6212 }
6213
6214 /*
6215 * For BPF_FIELD_EXISTS relo or when used BPF program has field
6216 * existence checks or kernel version/config checks, it's expected
6217 * that we might not find any candidates. In this case, if field
6218 * wasn't found in any candidate, the list of candidates shouldn't
6219 * change at all, we'll just handle relocating appropriately,
6220 * depending on relo's kind.
6221 */
6222 if (j > 0)
6223 cands->len = j;
6224
6225 /*
6226 * If no candidates were found, it might be both a programmer error,
6227 * as well as expected case, depending whether instruction w/
6228 * relocation is guarded in some way that makes it unreachable (dead
6229 * code) if relocation can't be resolved. This is handled in
6230 * bpf_core_patch_insn() uniformly by replacing that instruction with
6231 * BPF helper call insn (using invalid helper ID). If that instruction
6232 * is indeed unreachable, then it will be ignored and eliminated by
6233 * verifier. If it was an error, then verifier will complain and point
6234 * to a specific instruction number in its log.
6235 */
6236 if (j == 0) {
6237 pr_debug("prog '%s': relo #%d: no matching targets found\n",
6238 prog->name, relo_idx);
6239
6240 /* calculate single target relo result explicitly */
6241 err = bpf_core_calc_relo(prog, relo, relo_idx, &local_spec, NULL, &targ_res);
6242 if (err)
6243 return err;
6244 }
6245
6246 patch_insn:
6247 /* bpf_core_patch_insn() should know how to handle missing targ_spec */
6248 err = bpf_core_patch_insn(prog, relo, relo_idx, &targ_res);
6249 if (err) {
6250 pr_warn("prog '%s': relo #%d: failed to patch insn #%zu: %d\n",
6251 prog->name, relo_idx, relo->insn_off / BPF_INSN_SZ, err);
6252 return -EINVAL;
6253 }
6254
6255 return 0;
6256 }
6257
6258 static int
bpf_object__relocate_core(struct bpf_object * obj,const char * targ_btf_path)6259 bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
6260 {
6261 const struct btf_ext_info_sec *sec;
6262 const struct bpf_core_relo *rec;
6263 const struct btf_ext_info *seg;
6264 struct hashmap_entry *entry;
6265 struct hashmap *cand_cache = NULL;
6266 struct bpf_program *prog;
6267 const char *sec_name;
6268 int i, err = 0, insn_idx, sec_idx;
6269
6270 if (obj->btf_ext->core_relo_info.len == 0)
6271 return 0;
6272
6273 if (targ_btf_path) {
6274 obj->btf_vmlinux_override = btf__parse(targ_btf_path, NULL);
6275 if (IS_ERR_OR_NULL(obj->btf_vmlinux_override)) {
6276 err = PTR_ERR(obj->btf_vmlinux_override);
6277 pr_warn("failed to parse target BTF: %d\n", err);
6278 return err;
6279 }
6280 }
6281
6282 cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
6283 if (IS_ERR(cand_cache)) {
6284 err = PTR_ERR(cand_cache);
6285 goto out;
6286 }
6287
6288 seg = &obj->btf_ext->core_relo_info;
6289 for_each_btf_ext_sec(seg, sec) {
6290 sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
6291 if (str_is_empty(sec_name)) {
6292 err = -EINVAL;
6293 goto out;
6294 }
6295 /* bpf_object's ELF is gone by now so it's not easy to find
6296 * section index by section name, but we can find *any*
6297 * bpf_program within desired section name and use it's
6298 * prog->sec_idx to do a proper search by section index and
6299 * instruction offset
6300 */
6301 prog = NULL;
6302 for (i = 0; i < obj->nr_programs; i++) {
6303 prog = &obj->programs[i];
6304 if (strcmp(prog->sec_name, sec_name) == 0)
6305 break;
6306 }
6307 if (!prog) {
6308 pr_warn("sec '%s': failed to find a BPF program\n", sec_name);
6309 return -ENOENT;
6310 }
6311 sec_idx = prog->sec_idx;
6312
6313 pr_debug("sec '%s': found %d CO-RE relocations\n",
6314 sec_name, sec->num_info);
6315
6316 for_each_btf_ext_rec(seg, sec, i, rec) {
6317 insn_idx = rec->insn_off / BPF_INSN_SZ;
6318 prog = find_prog_by_sec_insn(obj, sec_idx, insn_idx);
6319 if (!prog) {
6320 pr_warn("sec '%s': failed to find program at insn #%d for CO-RE offset relocation #%d\n",
6321 sec_name, insn_idx, i);
6322 err = -EINVAL;
6323 goto out;
6324 }
6325 /* no need to apply CO-RE relocation if the program is
6326 * not going to be loaded
6327 */
6328 if (!prog->load)
6329 continue;
6330
6331 err = bpf_core_apply_relo(prog, rec, i, obj->btf, cand_cache);
6332 if (err) {
6333 pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
6334 prog->name, i, err);
6335 goto out;
6336 }
6337 }
6338 }
6339
6340 out:
6341 /* obj->btf_vmlinux and module BTFs are freed after object load */
6342 btf__free(obj->btf_vmlinux_override);
6343 obj->btf_vmlinux_override = NULL;
6344
6345 if (!IS_ERR_OR_NULL(cand_cache)) {
6346 hashmap__for_each_entry(cand_cache, entry, i) {
6347 bpf_core_free_cands(entry->value);
6348 }
6349 hashmap__free(cand_cache);
6350 }
6351 return err;
6352 }
6353
6354 /* Relocate data references within program code:
6355 * - map references;
6356 * - global variable references;
6357 * - extern references.
6358 */
6359 static int
bpf_object__relocate_data(struct bpf_object * obj,struct bpf_program * prog)6360 bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
6361 {
6362 int i;
6363
6364 for (i = 0; i < prog->nr_reloc; i++) {
6365 struct reloc_desc *relo = &prog->reloc_desc[i];
6366 struct bpf_insn *insn = &prog->insns[relo->insn_idx];
6367 struct extern_desc *ext;
6368
6369 switch (relo->type) {
6370 case RELO_LD64:
6371 insn[0].src_reg = BPF_PSEUDO_MAP_FD;
6372 insn[0].imm = obj->maps[relo->map_idx].fd;
6373 break;
6374 case RELO_DATA:
6375 insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
6376 insn[1].imm = insn[0].imm + relo->sym_off;
6377 insn[0].imm = obj->maps[relo->map_idx].fd;
6378 break;
6379 case RELO_EXTERN_VAR:
6380 ext = &obj->externs[relo->sym_off];
6381 if (ext->type == EXT_KCFG) {
6382 insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
6383 insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
6384 insn[1].imm = ext->kcfg.data_off;
6385 } else /* EXT_KSYM */ {
6386 if (ext->ksym.type_id) { /* typed ksyms */
6387 insn[0].src_reg = BPF_PSEUDO_BTF_ID;
6388 insn[0].imm = ext->ksym.kernel_btf_id;
6389 insn[1].imm = ext->ksym.kernel_btf_obj_fd;
6390 } else { /* typeless ksyms */
6391 insn[0].imm = (__u32)ext->ksym.addr;
6392 insn[1].imm = ext->ksym.addr >> 32;
6393 }
6394 }
6395 break;
6396 case RELO_EXTERN_FUNC:
6397 ext = &obj->externs[relo->sym_off];
6398 insn[0].src_reg = BPF_PSEUDO_KFUNC_CALL;
6399 insn[0].imm = ext->ksym.kernel_btf_id;
6400 break;
6401 case RELO_SUBPROG_ADDR:
6402 insn[0].src_reg = BPF_PSEUDO_FUNC;
6403 /* will be handled as a follow up pass */
6404 break;
6405 case RELO_CALL:
6406 /* will be handled as a follow up pass */
6407 break;
6408 default:
6409 pr_warn("prog '%s': relo #%d: bad relo type %d\n",
6410 prog->name, i, relo->type);
6411 return -EINVAL;
6412 }
6413 }
6414
6415 return 0;
6416 }
6417
adjust_prog_btf_ext_info(const struct bpf_object * obj,const struct bpf_program * prog,const struct btf_ext_info * ext_info,void ** prog_info,__u32 * prog_rec_cnt,__u32 * prog_rec_sz)6418 static int adjust_prog_btf_ext_info(const struct bpf_object *obj,
6419 const struct bpf_program *prog,
6420 const struct btf_ext_info *ext_info,
6421 void **prog_info, __u32 *prog_rec_cnt,
6422 __u32 *prog_rec_sz)
6423 {
6424 void *copy_start = NULL, *copy_end = NULL;
6425 void *rec, *rec_end, *new_prog_info;
6426 const struct btf_ext_info_sec *sec;
6427 size_t old_sz, new_sz;
6428 const char *sec_name;
6429 int i, off_adj;
6430
6431 for_each_btf_ext_sec(ext_info, sec) {
6432 sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
6433 if (!sec_name)
6434 return -EINVAL;
6435 if (strcmp(sec_name, prog->sec_name) != 0)
6436 continue;
6437
6438 for_each_btf_ext_rec(ext_info, sec, i, rec) {
6439 __u32 insn_off = *(__u32 *)rec / BPF_INSN_SZ;
6440
6441 if (insn_off < prog->sec_insn_off)
6442 continue;
6443 if (insn_off >= prog->sec_insn_off + prog->sec_insn_cnt)
6444 break;
6445
6446 if (!copy_start)
6447 copy_start = rec;
6448 copy_end = rec + ext_info->rec_size;
6449 }
6450
6451 if (!copy_start)
6452 return -ENOENT;
6453
6454 /* append func/line info of a given (sub-)program to the main
6455 * program func/line info
6456 */
6457 old_sz = (size_t)(*prog_rec_cnt) * ext_info->rec_size;
6458 new_sz = old_sz + (copy_end - copy_start);
6459 new_prog_info = realloc(*prog_info, new_sz);
6460 if (!new_prog_info)
6461 return -ENOMEM;
6462 *prog_info = new_prog_info;
6463 *prog_rec_cnt = new_sz / ext_info->rec_size;
6464 memcpy(new_prog_info + old_sz, copy_start, copy_end - copy_start);
6465
6466 /* Kernel instruction offsets are in units of 8-byte
6467 * instructions, while .BTF.ext instruction offsets generated
6468 * by Clang are in units of bytes. So convert Clang offsets
6469 * into kernel offsets and adjust offset according to program
6470 * relocated position.
6471 */
6472 off_adj = prog->sub_insn_off - prog->sec_insn_off;
6473 rec = new_prog_info + old_sz;
6474 rec_end = new_prog_info + new_sz;
6475 for (; rec < rec_end; rec += ext_info->rec_size) {
6476 __u32 *insn_off = rec;
6477
6478 *insn_off = *insn_off / BPF_INSN_SZ + off_adj;
6479 }
6480 *prog_rec_sz = ext_info->rec_size;
6481 return 0;
6482 }
6483
6484 return -ENOENT;
6485 }
6486
6487 static int
reloc_prog_func_and_line_info(const struct bpf_object * obj,struct bpf_program * main_prog,const struct bpf_program * prog)6488 reloc_prog_func_and_line_info(const struct bpf_object *obj,
6489 struct bpf_program *main_prog,
6490 const struct bpf_program *prog)
6491 {
6492 int err;
6493
6494 /* no .BTF.ext relocation if .BTF.ext is missing or kernel doesn't
6495 * supprot func/line info
6496 */
6497 if (!obj->btf_ext || !kernel_supports(FEAT_BTF_FUNC))
6498 return 0;
6499
6500 /* only attempt func info relocation if main program's func_info
6501 * relocation was successful
6502 */
6503 if (main_prog != prog && !main_prog->func_info)
6504 goto line_info;
6505
6506 err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->func_info,
6507 &main_prog->func_info,
6508 &main_prog->func_info_cnt,
6509 &main_prog->func_info_rec_size);
6510 if (err) {
6511 if (err != -ENOENT) {
6512 pr_warn("prog '%s': error relocating .BTF.ext function info: %d\n",
6513 prog->name, err);
6514 return err;
6515 }
6516 if (main_prog->func_info) {
6517 /*
6518 * Some info has already been found but has problem
6519 * in the last btf_ext reloc. Must have to error out.
6520 */
6521 pr_warn("prog '%s': missing .BTF.ext function info.\n", prog->name);
6522 return err;
6523 }
6524 /* Have problem loading the very first info. Ignore the rest. */
6525 pr_warn("prog '%s': missing .BTF.ext function info for the main program, skipping all of .BTF.ext func info.\n",
6526 prog->name);
6527 }
6528
6529 line_info:
6530 /* don't relocate line info if main program's relocation failed */
6531 if (main_prog != prog && !main_prog->line_info)
6532 return 0;
6533
6534 err = adjust_prog_btf_ext_info(obj, prog, &obj->btf_ext->line_info,
6535 &main_prog->line_info,
6536 &main_prog->line_info_cnt,
6537 &main_prog->line_info_rec_size);
6538 if (err) {
6539 if (err != -ENOENT) {
6540 pr_warn("prog '%s': error relocating .BTF.ext line info: %d\n",
6541 prog->name, err);
6542 return err;
6543 }
6544 if (main_prog->line_info) {
6545 /*
6546 * Some info has already been found but has problem
6547 * in the last btf_ext reloc. Must have to error out.
6548 */
6549 pr_warn("prog '%s': missing .BTF.ext line info.\n", prog->name);
6550 return err;
6551 }
6552 /* Have problem loading the very first info. Ignore the rest. */
6553 pr_warn("prog '%s': missing .BTF.ext line info for the main program, skipping all of .BTF.ext line info.\n",
6554 prog->name);
6555 }
6556 return 0;
6557 }
6558
cmp_relo_by_insn_idx(const void * key,const void * elem)6559 static int cmp_relo_by_insn_idx(const void *key, const void *elem)
6560 {
6561 size_t insn_idx = *(const size_t *)key;
6562 const struct reloc_desc *relo = elem;
6563
6564 if (insn_idx == relo->insn_idx)
6565 return 0;
6566 return insn_idx < relo->insn_idx ? -1 : 1;
6567 }
6568
find_prog_insn_relo(const struct bpf_program * prog,size_t insn_idx)6569 static struct reloc_desc *find_prog_insn_relo(const struct bpf_program *prog, size_t insn_idx)
6570 {
6571 return bsearch(&insn_idx, prog->reloc_desc, prog->nr_reloc,
6572 sizeof(*prog->reloc_desc), cmp_relo_by_insn_idx);
6573 }
6574
6575 static int
bpf_object__reloc_code(struct bpf_object * obj,struct bpf_program * main_prog,struct bpf_program * prog)6576 bpf_object__reloc_code(struct bpf_object *obj, struct bpf_program *main_prog,
6577 struct bpf_program *prog)
6578 {
6579 size_t sub_insn_idx, insn_idx, new_cnt;
6580 struct bpf_program *subprog;
6581 struct bpf_insn *insns, *insn;
6582 struct reloc_desc *relo;
6583 int err;
6584
6585 err = reloc_prog_func_and_line_info(obj, main_prog, prog);
6586 if (err)
6587 return err;
6588
6589 for (insn_idx = 0; insn_idx < prog->sec_insn_cnt; insn_idx++) {
6590 insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
6591 if (!insn_is_subprog_call(insn) && !insn_is_pseudo_func(insn))
6592 continue;
6593
6594 relo = find_prog_insn_relo(prog, insn_idx);
6595 if (relo && relo->type != RELO_CALL && relo->type != RELO_SUBPROG_ADDR) {
6596 pr_warn("prog '%s': unexpected relo for insn #%zu, type %d\n",
6597 prog->name, insn_idx, relo->type);
6598 return -LIBBPF_ERRNO__RELOC;
6599 }
6600 if (relo) {
6601 /* sub-program instruction index is a combination of
6602 * an offset of a symbol pointed to by relocation and
6603 * call instruction's imm field; for global functions,
6604 * call always has imm = -1, but for static functions
6605 * relocation is against STT_SECTION and insn->imm
6606 * points to a start of a static function
6607 *
6608 * for subprog addr relocation, the relo->sym_off + insn->imm is
6609 * the byte offset in the corresponding section.
6610 */
6611 if (relo->type == RELO_CALL)
6612 sub_insn_idx = relo->sym_off / BPF_INSN_SZ + insn->imm + 1;
6613 else
6614 sub_insn_idx = (relo->sym_off + insn->imm) / BPF_INSN_SZ;
6615 } else if (insn_is_pseudo_func(insn)) {
6616 /*
6617 * RELO_SUBPROG_ADDR relo is always emitted even if both
6618 * functions are in the same section, so it shouldn't reach here.
6619 */
6620 pr_warn("prog '%s': missing subprog addr relo for insn #%zu\n",
6621 prog->name, insn_idx);
6622 return -LIBBPF_ERRNO__RELOC;
6623 } else {
6624 /* if subprogram call is to a static function within
6625 * the same ELF section, there won't be any relocation
6626 * emitted, but it also means there is no additional
6627 * offset necessary, insns->imm is relative to
6628 * instruction's original position within the section
6629 */
6630 sub_insn_idx = prog->sec_insn_off + insn_idx + insn->imm + 1;
6631 }
6632
6633 /* we enforce that sub-programs should be in .text section */
6634 subprog = find_prog_by_sec_insn(obj, obj->efile.text_shndx, sub_insn_idx);
6635 if (!subprog) {
6636 pr_warn("prog '%s': no .text section found yet sub-program call exists\n",
6637 prog->name);
6638 return -LIBBPF_ERRNO__RELOC;
6639 }
6640
6641 /* if it's the first call instruction calling into this
6642 * subprogram (meaning this subprog hasn't been processed
6643 * yet) within the context of current main program:
6644 * - append it at the end of main program's instructions blog;
6645 * - process is recursively, while current program is put on hold;
6646 * - if that subprogram calls some other not yet processes
6647 * subprogram, same thing will happen recursively until
6648 * there are no more unprocesses subprograms left to append
6649 * and relocate.
6650 */
6651 if (subprog->sub_insn_off == 0) {
6652 subprog->sub_insn_off = main_prog->insns_cnt;
6653
6654 new_cnt = main_prog->insns_cnt + subprog->insns_cnt;
6655 insns = libbpf_reallocarray(main_prog->insns, new_cnt, sizeof(*insns));
6656 if (!insns) {
6657 pr_warn("prog '%s': failed to realloc prog code\n", main_prog->name);
6658 return -ENOMEM;
6659 }
6660 main_prog->insns = insns;
6661 main_prog->insns_cnt = new_cnt;
6662
6663 memcpy(main_prog->insns + subprog->sub_insn_off, subprog->insns,
6664 subprog->insns_cnt * sizeof(*insns));
6665
6666 pr_debug("prog '%s': added %zu insns from sub-prog '%s'\n",
6667 main_prog->name, subprog->insns_cnt, subprog->name);
6668
6669 err = bpf_object__reloc_code(obj, main_prog, subprog);
6670 if (err)
6671 return err;
6672 }
6673
6674 /* main_prog->insns memory could have been re-allocated, so
6675 * calculate pointer again
6676 */
6677 insn = &main_prog->insns[prog->sub_insn_off + insn_idx];
6678 /* calculate correct instruction position within current main
6679 * prog; each main prog can have a different set of
6680 * subprograms appended (potentially in different order as
6681 * well), so position of any subprog can be different for
6682 * different main programs */
6683 insn->imm = subprog->sub_insn_off - (prog->sub_insn_off + insn_idx) - 1;
6684
6685 pr_debug("prog '%s': insn #%zu relocated, imm %d points to subprog '%s' (now at %zu offset)\n",
6686 prog->name, insn_idx, insn->imm, subprog->name, subprog->sub_insn_off);
6687 }
6688
6689 return 0;
6690 }
6691
6692 /*
6693 * Relocate sub-program calls.
6694 *
6695 * Algorithm operates as follows. Each entry-point BPF program (referred to as
6696 * main prog) is processed separately. For each subprog (non-entry functions,
6697 * that can be called from either entry progs or other subprogs) gets their
6698 * sub_insn_off reset to zero. This serves as indicator that this subprogram
6699 * hasn't been yet appended and relocated within current main prog. Once its
6700 * relocated, sub_insn_off will point at the position within current main prog
6701 * where given subprog was appended. This will further be used to relocate all
6702 * the call instructions jumping into this subprog.
6703 *
6704 * We start with main program and process all call instructions. If the call
6705 * is into a subprog that hasn't been processed (i.e., subprog->sub_insn_off
6706 * is zero), subprog instructions are appended at the end of main program's
6707 * instruction array. Then main program is "put on hold" while we recursively
6708 * process newly appended subprogram. If that subprogram calls into another
6709 * subprogram that hasn't been appended, new subprogram is appended again to
6710 * the *main* prog's instructions (subprog's instructions are always left
6711 * untouched, as they need to be in unmodified state for subsequent main progs
6712 * and subprog instructions are always sent only as part of a main prog) and
6713 * the process continues recursively. Once all the subprogs called from a main
6714 * prog or any of its subprogs are appended (and relocated), all their
6715 * positions within finalized instructions array are known, so it's easy to
6716 * rewrite call instructions with correct relative offsets, corresponding to
6717 * desired target subprog.
6718 *
6719 * Its important to realize that some subprogs might not be called from some
6720 * main prog and any of its called/used subprogs. Those will keep their
6721 * subprog->sub_insn_off as zero at all times and won't be appended to current
6722 * main prog and won't be relocated within the context of current main prog.
6723 * They might still be used from other main progs later.
6724 *
6725 * Visually this process can be shown as below. Suppose we have two main
6726 * programs mainA and mainB and BPF object contains three subprogs: subA,
6727 * subB, and subC. mainA calls only subA, mainB calls only subC, but subA and
6728 * subC both call subB:
6729 *
6730 * +--------+ +-------+
6731 * | v v |
6732 * +--+---+ +--+-+-+ +---+--+
6733 * | subA | | subB | | subC |
6734 * +--+---+ +------+ +---+--+
6735 * ^ ^
6736 * | |
6737 * +---+-------+ +------+----+
6738 * | mainA | | mainB |
6739 * +-----------+ +-----------+
6740 *
6741 * We'll start relocating mainA, will find subA, append it and start
6742 * processing sub A recursively:
6743 *
6744 * +-----------+------+
6745 * | mainA | subA |
6746 * +-----------+------+
6747 *
6748 * At this point we notice that subB is used from subA, so we append it and
6749 * relocate (there are no further subcalls from subB):
6750 *
6751 * +-----------+------+------+
6752 * | mainA | subA | subB |
6753 * +-----------+------+------+
6754 *
6755 * At this point, we relocate subA calls, then go one level up and finish with
6756 * relocatin mainA calls. mainA is done.
6757 *
6758 * For mainB process is similar but results in different order. We start with
6759 * mainB and skip subA and subB, as mainB never calls them (at least
6760 * directly), but we see subC is needed, so we append and start processing it:
6761 *
6762 * +-----------+------+
6763 * | mainB | subC |
6764 * +-----------+------+
6765 * Now we see subC needs subB, so we go back to it, append and relocate it:
6766 *
6767 * +-----------+------+------+
6768 * | mainB | subC | subB |
6769 * +-----------+------+------+
6770 *
6771 * At this point we unwind recursion, relocate calls in subC, then in mainB.
6772 */
6773 static int
bpf_object__relocate_calls(struct bpf_object * obj,struct bpf_program * prog)6774 bpf_object__relocate_calls(struct bpf_object *obj, struct bpf_program *prog)
6775 {
6776 struct bpf_program *subprog;
6777 int i, err;
6778
6779 /* mark all subprogs as not relocated (yet) within the context of
6780 * current main program
6781 */
6782 for (i = 0; i < obj->nr_programs; i++) {
6783 subprog = &obj->programs[i];
6784 if (!prog_is_subprog(obj, subprog))
6785 continue;
6786
6787 subprog->sub_insn_off = 0;
6788 }
6789
6790 err = bpf_object__reloc_code(obj, prog, prog);
6791 if (err)
6792 return err;
6793
6794
6795 return 0;
6796 }
6797
6798 static int
bpf_object__relocate(struct bpf_object * obj,const char * targ_btf_path)6799 bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
6800 {
6801 struct bpf_program *prog;
6802 size_t i;
6803 int err;
6804
6805 if (obj->btf_ext) {
6806 err = bpf_object__relocate_core(obj, targ_btf_path);
6807 if (err) {
6808 pr_warn("failed to perform CO-RE relocations: %d\n",
6809 err);
6810 return err;
6811 }
6812 }
6813 /* relocate data references first for all programs and sub-programs,
6814 * as they don't change relative to code locations, so subsequent
6815 * subprogram processing won't need to re-calculate any of them
6816 */
6817 for (i = 0; i < obj->nr_programs; i++) {
6818 prog = &obj->programs[i];
6819 err = bpf_object__relocate_data(obj, prog);
6820 if (err) {
6821 pr_warn("prog '%s': failed to relocate data references: %d\n",
6822 prog->name, err);
6823 return err;
6824 }
6825 }
6826 /* now relocate subprogram calls and append used subprograms to main
6827 * programs; each copy of subprogram code needs to be relocated
6828 * differently for each main program, because its code location might
6829 * have changed
6830 */
6831 for (i = 0; i < obj->nr_programs; i++) {
6832 prog = &obj->programs[i];
6833 /* sub-program's sub-calls are relocated within the context of
6834 * its main program only
6835 */
6836 if (prog_is_subprog(obj, prog))
6837 continue;
6838
6839 err = bpf_object__relocate_calls(obj, prog);
6840 if (err) {
6841 pr_warn("prog '%s': failed to relocate calls: %d\n",
6842 prog->name, err);
6843 return err;
6844 }
6845 }
6846 /* free up relocation descriptors */
6847 for (i = 0; i < obj->nr_programs; i++) {
6848 prog = &obj->programs[i];
6849 zfree(&prog->reloc_desc);
6850 prog->nr_reloc = 0;
6851 }
6852 return 0;
6853 }
6854
6855 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
6856 GElf_Shdr *shdr, Elf_Data *data);
6857
bpf_object__collect_map_relos(struct bpf_object * obj,GElf_Shdr * shdr,Elf_Data * data)6858 static int bpf_object__collect_map_relos(struct bpf_object *obj,
6859 GElf_Shdr *shdr, Elf_Data *data)
6860 {
6861 const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *);
6862 int i, j, nrels, new_sz;
6863 const struct btf_var_secinfo *vi = NULL;
6864 const struct btf_type *sec, *var, *def;
6865 struct bpf_map *map = NULL, *targ_map;
6866 const struct btf_member *member;
6867 const char *name, *mname;
6868 Elf_Data *symbols;
6869 unsigned int moff;
6870 GElf_Sym sym;
6871 GElf_Rel rel;
6872 void *tmp;
6873
6874 if (!obj->efile.btf_maps_sec_btf_id || !obj->btf)
6875 return -EINVAL;
6876 sec = btf__type_by_id(obj->btf, obj->efile.btf_maps_sec_btf_id);
6877 if (!sec)
6878 return -EINVAL;
6879
6880 symbols = obj->efile.symbols;
6881 nrels = shdr->sh_size / shdr->sh_entsize;
6882 for (i = 0; i < nrels; i++) {
6883 if (!gelf_getrel(data, i, &rel)) {
6884 pr_warn(".maps relo #%d: failed to get ELF relo\n", i);
6885 return -LIBBPF_ERRNO__FORMAT;
6886 }
6887 if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
6888 pr_warn(".maps relo #%d: symbol %zx not found\n",
6889 i, (size_t)GELF_R_SYM(rel.r_info));
6890 return -LIBBPF_ERRNO__FORMAT;
6891 }
6892 name = elf_sym_str(obj, sym.st_name) ?: "<?>";
6893 if (sym.st_shndx != obj->efile.btf_maps_shndx) {
6894 pr_warn(".maps relo #%d: '%s' isn't a BTF-defined map\n",
6895 i, name);
6896 return -LIBBPF_ERRNO__RELOC;
6897 }
6898
6899 pr_debug(".maps relo #%d: for %zd value %zd rel.r_offset %zu name %d ('%s')\n",
6900 i, (ssize_t)(rel.r_info >> 32), (size_t)sym.st_value,
6901 (size_t)rel.r_offset, sym.st_name, name);
6902
6903 for (j = 0; j < obj->nr_maps; j++) {
6904 map = &obj->maps[j];
6905 if (map->sec_idx != obj->efile.btf_maps_shndx)
6906 continue;
6907
6908 vi = btf_var_secinfos(sec) + map->btf_var_idx;
6909 if (vi->offset <= rel.r_offset &&
6910 rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size)
6911 break;
6912 }
6913 if (j == obj->nr_maps) {
6914 pr_warn(".maps relo #%d: cannot find map '%s' at rel.r_offset %zu\n",
6915 i, name, (size_t)rel.r_offset);
6916 return -EINVAL;
6917 }
6918
6919 if (!bpf_map_type__is_map_in_map(map->def.type))
6920 return -EINVAL;
6921 if (map->def.type == BPF_MAP_TYPE_HASH_OF_MAPS &&
6922 map->def.key_size != sizeof(int)) {
6923 pr_warn(".maps relo #%d: hash-of-maps '%s' should have key size %zu.\n",
6924 i, map->name, sizeof(int));
6925 return -EINVAL;
6926 }
6927
6928 targ_map = bpf_object__find_map_by_name(obj, name);
6929 if (!targ_map)
6930 return -ESRCH;
6931
6932 var = btf__type_by_id(obj->btf, vi->type);
6933 def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
6934 if (btf_vlen(def) == 0)
6935 return -EINVAL;
6936 member = btf_members(def) + btf_vlen(def) - 1;
6937 mname = btf__name_by_offset(obj->btf, member->name_off);
6938 if (strcmp(mname, "values"))
6939 return -EINVAL;
6940
6941 moff = btf_member_bit_offset(def, btf_vlen(def) - 1) / 8;
6942 if (rel.r_offset - vi->offset < moff)
6943 return -EINVAL;
6944
6945 moff = rel.r_offset - vi->offset - moff;
6946 /* here we use BPF pointer size, which is always 64 bit, as we
6947 * are parsing ELF that was built for BPF target
6948 */
6949 if (moff % bpf_ptr_sz)
6950 return -EINVAL;
6951 moff /= bpf_ptr_sz;
6952 if (moff >= map->init_slots_sz) {
6953 new_sz = moff + 1;
6954 tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
6955 if (!tmp)
6956 return -ENOMEM;
6957 map->init_slots = tmp;
6958 memset(map->init_slots + map->init_slots_sz, 0,
6959 (new_sz - map->init_slots_sz) * host_ptr_sz);
6960 map->init_slots_sz = new_sz;
6961 }
6962 map->init_slots[moff] = targ_map;
6963
6964 pr_debug(".maps relo #%d: map '%s' slot [%d] points to map '%s'\n",
6965 i, map->name, moff, name);
6966 }
6967
6968 return 0;
6969 }
6970
cmp_relocs(const void * _a,const void * _b)6971 static int cmp_relocs(const void *_a, const void *_b)
6972 {
6973 const struct reloc_desc *a = _a;
6974 const struct reloc_desc *b = _b;
6975
6976 if (a->insn_idx != b->insn_idx)
6977 return a->insn_idx < b->insn_idx ? -1 : 1;
6978
6979 /* no two relocations should have the same insn_idx, but ... */
6980 if (a->type != b->type)
6981 return a->type < b->type ? -1 : 1;
6982
6983 return 0;
6984 }
6985
bpf_object__collect_relos(struct bpf_object * obj)6986 static int bpf_object__collect_relos(struct bpf_object *obj)
6987 {
6988 int i, err;
6989
6990 for (i = 0; i < obj->efile.nr_reloc_sects; i++) {
6991 GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr;
6992 Elf_Data *data = obj->efile.reloc_sects[i].data;
6993 int idx = shdr->sh_info;
6994
6995 if (shdr->sh_type != SHT_REL) {
6996 pr_warn("internal error at %d\n", __LINE__);
6997 return -LIBBPF_ERRNO__INTERNAL;
6998 }
6999
7000 if (idx == obj->efile.st_ops_shndx)
7001 err = bpf_object__collect_st_ops_relos(obj, shdr, data);
7002 else if (idx == obj->efile.btf_maps_shndx)
7003 err = bpf_object__collect_map_relos(obj, shdr, data);
7004 else
7005 err = bpf_object__collect_prog_relos(obj, shdr, data);
7006 if (err)
7007 return err;
7008 }
7009
7010 for (i = 0; i < obj->nr_programs; i++) {
7011 struct bpf_program *p = &obj->programs[i];
7012
7013 if (!p->nr_reloc)
7014 continue;
7015
7016 qsort(p->reloc_desc, p->nr_reloc, sizeof(*p->reloc_desc), cmp_relocs);
7017 }
7018 return 0;
7019 }
7020
insn_is_helper_call(struct bpf_insn * insn,enum bpf_func_id * func_id)7021 static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
7022 {
7023 if (BPF_CLASS(insn->code) == BPF_JMP &&
7024 BPF_OP(insn->code) == BPF_CALL &&
7025 BPF_SRC(insn->code) == BPF_K &&
7026 insn->src_reg == 0 &&
7027 insn->dst_reg == 0) {
7028 *func_id = insn->imm;
7029 return true;
7030 }
7031 return false;
7032 }
7033
bpf_object__sanitize_prog(struct bpf_object * obj,struct bpf_program * prog)7034 static int bpf_object__sanitize_prog(struct bpf_object *obj, struct bpf_program *prog)
7035 {
7036 struct bpf_insn *insn = prog->insns;
7037 enum bpf_func_id func_id;
7038 int i;
7039
7040 for (i = 0; i < prog->insns_cnt; i++, insn++) {
7041 if (!insn_is_helper_call(insn, &func_id))
7042 continue;
7043
7044 /* on kernels that don't yet support
7045 * bpf_probe_read_{kernel,user}[_str] helpers, fall back
7046 * to bpf_probe_read() which works well for old kernels
7047 */
7048 switch (func_id) {
7049 case BPF_FUNC_probe_read_kernel:
7050 case BPF_FUNC_probe_read_user:
7051 if (!kernel_supports(FEAT_PROBE_READ_KERN))
7052 insn->imm = BPF_FUNC_probe_read;
7053 break;
7054 case BPF_FUNC_probe_read_kernel_str:
7055 case BPF_FUNC_probe_read_user_str:
7056 if (!kernel_supports(FEAT_PROBE_READ_KERN))
7057 insn->imm = BPF_FUNC_probe_read_str;
7058 break;
7059 default:
7060 break;
7061 }
7062 }
7063 return 0;
7064 }
7065
7066 static int
load_program(struct bpf_program * prog,struct bpf_insn * insns,int insns_cnt,char * license,__u32 kern_version,int * pfd)7067 load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
7068 char *license, __u32 kern_version, int *pfd)
7069 {
7070 struct bpf_prog_load_params load_attr = {};
7071 char *cp, errmsg[STRERR_BUFSIZE];
7072 size_t log_buf_size = 0;
7073 char *log_buf = NULL;
7074 int btf_fd, ret;
7075
7076 if (prog->type == BPF_PROG_TYPE_UNSPEC) {
7077 /*
7078 * The program type must be set. Most likely we couldn't find a proper
7079 * section definition at load time, and thus we didn't infer the type.
7080 */
7081 pr_warn("prog '%s': missing BPF prog type, check ELF section name '%s'\n",
7082 prog->name, prog->sec_name);
7083 return -EINVAL;
7084 }
7085
7086 if (!insns || !insns_cnt)
7087 return -EINVAL;
7088
7089 load_attr.prog_type = prog->type;
7090 /* old kernels might not support specifying expected_attach_type */
7091 if (!kernel_supports(FEAT_EXP_ATTACH_TYPE) && prog->sec_def &&
7092 prog->sec_def->is_exp_attach_type_optional)
7093 load_attr.expected_attach_type = 0;
7094 else
7095 load_attr.expected_attach_type = prog->expected_attach_type;
7096 if (kernel_supports(FEAT_PROG_NAME))
7097 load_attr.name = prog->name;
7098 load_attr.insns = insns;
7099 load_attr.insn_cnt = insns_cnt;
7100 load_attr.license = license;
7101 load_attr.attach_btf_id = prog->attach_btf_id;
7102 if (prog->attach_prog_fd)
7103 load_attr.attach_prog_fd = prog->attach_prog_fd;
7104 else
7105 load_attr.attach_btf_obj_fd = prog->attach_btf_obj_fd;
7106 load_attr.attach_btf_id = prog->attach_btf_id;
7107 load_attr.kern_version = kern_version;
7108 load_attr.prog_ifindex = prog->prog_ifindex;
7109
7110 /* specify func_info/line_info only if kernel supports them */
7111 btf_fd = bpf_object__btf_fd(prog->obj);
7112 if (btf_fd >= 0 && kernel_supports(FEAT_BTF_FUNC)) {
7113 load_attr.prog_btf_fd = btf_fd;
7114 load_attr.func_info = prog->func_info;
7115 load_attr.func_info_rec_size = prog->func_info_rec_size;
7116 load_attr.func_info_cnt = prog->func_info_cnt;
7117 load_attr.line_info = prog->line_info;
7118 load_attr.line_info_rec_size = prog->line_info_rec_size;
7119 load_attr.line_info_cnt = prog->line_info_cnt;
7120 }
7121 load_attr.log_level = prog->log_level;
7122 load_attr.prog_flags = prog->prog_flags;
7123
7124 retry_load:
7125 if (log_buf_size) {
7126 log_buf = malloc(log_buf_size);
7127 if (!log_buf)
7128 return -ENOMEM;
7129
7130 *log_buf = 0;
7131 }
7132
7133 load_attr.log_buf = log_buf;
7134 load_attr.log_buf_sz = log_buf_size;
7135 ret = libbpf__bpf_prog_load(&load_attr);
7136
7137 if (ret >= 0) {
7138 if (log_buf && load_attr.log_level)
7139 pr_debug("verifier log:\n%s", log_buf);
7140
7141 if (prog->obj->rodata_map_idx >= 0 &&
7142 kernel_supports(FEAT_PROG_BIND_MAP)) {
7143 struct bpf_map *rodata_map =
7144 &prog->obj->maps[prog->obj->rodata_map_idx];
7145
7146 if (bpf_prog_bind_map(ret, bpf_map__fd(rodata_map), NULL)) {
7147 cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
7148 pr_warn("prog '%s': failed to bind .rodata map: %s\n",
7149 prog->name, cp);
7150 /* Don't fail hard if can't bind rodata. */
7151 }
7152 }
7153
7154 *pfd = ret;
7155 ret = 0;
7156 goto out;
7157 }
7158
7159 if (!log_buf || errno == ENOSPC) {
7160 log_buf_size = max((size_t)BPF_LOG_BUF_SIZE,
7161 log_buf_size << 1);
7162
7163 free(log_buf);
7164 goto retry_load;
7165 }
7166 ret = errno ? -errno : -LIBBPF_ERRNO__LOAD;
7167 cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
7168 pr_warn("load bpf program failed: %s\n", cp);
7169 pr_perm_msg(ret);
7170
7171 if (log_buf && log_buf[0] != '\0') {
7172 ret = -LIBBPF_ERRNO__VERIFY;
7173 pr_warn("-- BEGIN DUMP LOG ---\n");
7174 pr_warn("\n%s\n", log_buf);
7175 pr_warn("-- END LOG --\n");
7176 } else if (load_attr.insn_cnt >= BPF_MAXINSNS) {
7177 pr_warn("Program too large (%zu insns), at most %d insns\n",
7178 load_attr.insn_cnt, BPF_MAXINSNS);
7179 ret = -LIBBPF_ERRNO__PROG2BIG;
7180 } else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) {
7181 /* Wrong program type? */
7182 int fd;
7183
7184 load_attr.prog_type = BPF_PROG_TYPE_KPROBE;
7185 load_attr.expected_attach_type = 0;
7186 load_attr.log_buf = NULL;
7187 load_attr.log_buf_sz = 0;
7188 fd = libbpf__bpf_prog_load(&load_attr);
7189 if (fd >= 0) {
7190 close(fd);
7191 ret = -LIBBPF_ERRNO__PROGTYPE;
7192 goto out;
7193 }
7194 }
7195
7196 out:
7197 free(log_buf);
7198 return ret;
7199 }
7200
7201 static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id);
7202
bpf_program__load(struct bpf_program * prog,char * license,__u32 kern_ver)7203 int bpf_program__load(struct bpf_program *prog, char *license, __u32 kern_ver)
7204 {
7205 int err = 0, fd, i;
7206
7207 if (prog->obj->loaded) {
7208 pr_warn("prog '%s': can't load after object was loaded\n", prog->name);
7209 return -EINVAL;
7210 }
7211
7212 if ((prog->type == BPF_PROG_TYPE_TRACING ||
7213 prog->type == BPF_PROG_TYPE_LSM ||
7214 prog->type == BPF_PROG_TYPE_EXT) && !prog->attach_btf_id) {
7215 int btf_obj_fd = 0, btf_type_id = 0;
7216
7217 err = libbpf_find_attach_btf_id(prog, &btf_obj_fd, &btf_type_id);
7218 if (err)
7219 return err;
7220
7221 prog->attach_btf_obj_fd = btf_obj_fd;
7222 prog->attach_btf_id = btf_type_id;
7223 }
7224
7225 if (prog->instances.nr < 0 || !prog->instances.fds) {
7226 if (prog->preprocessor) {
7227 pr_warn("Internal error: can't load program '%s'\n",
7228 prog->name);
7229 return -LIBBPF_ERRNO__INTERNAL;
7230 }
7231
7232 prog->instances.fds = malloc(sizeof(int));
7233 if (!prog->instances.fds) {
7234 pr_warn("Not enough memory for BPF fds\n");
7235 return -ENOMEM;
7236 }
7237 prog->instances.nr = 1;
7238 prog->instances.fds[0] = -1;
7239 }
7240
7241 if (!prog->preprocessor) {
7242 if (prog->instances.nr != 1) {
7243 pr_warn("prog '%s': inconsistent nr(%d) != 1\n",
7244 prog->name, prog->instances.nr);
7245 }
7246 err = load_program(prog, prog->insns, prog->insns_cnt,
7247 license, kern_ver, &fd);
7248 if (!err)
7249 prog->instances.fds[0] = fd;
7250 goto out;
7251 }
7252
7253 for (i = 0; i < prog->instances.nr; i++) {
7254 struct bpf_prog_prep_result result;
7255 bpf_program_prep_t preprocessor = prog->preprocessor;
7256
7257 memset(&result, 0, sizeof(result));
7258 err = preprocessor(prog, i, prog->insns,
7259 prog->insns_cnt, &result);
7260 if (err) {
7261 pr_warn("Preprocessing the %dth instance of program '%s' failed\n",
7262 i, prog->name);
7263 goto out;
7264 }
7265
7266 if (!result.new_insn_ptr || !result.new_insn_cnt) {
7267 pr_debug("Skip loading the %dth instance of program '%s'\n",
7268 i, prog->name);
7269 prog->instances.fds[i] = -1;
7270 if (result.pfd)
7271 *result.pfd = -1;
7272 continue;
7273 }
7274
7275 err = load_program(prog, result.new_insn_ptr,
7276 result.new_insn_cnt, license, kern_ver, &fd);
7277 if (err) {
7278 pr_warn("Loading the %dth instance of program '%s' failed\n",
7279 i, prog->name);
7280 goto out;
7281 }
7282
7283 if (result.pfd)
7284 *result.pfd = fd;
7285 prog->instances.fds[i] = fd;
7286 }
7287 out:
7288 if (err)
7289 pr_warn("failed to load program '%s'\n", prog->name);
7290 zfree(&prog->insns);
7291 prog->insns_cnt = 0;
7292 return err;
7293 }
7294
7295 static int
bpf_object__load_progs(struct bpf_object * obj,int log_level)7296 bpf_object__load_progs(struct bpf_object *obj, int log_level)
7297 {
7298 struct bpf_program *prog;
7299 size_t i;
7300 int err;
7301
7302 for (i = 0; i < obj->nr_programs; i++) {
7303 prog = &obj->programs[i];
7304 err = bpf_object__sanitize_prog(obj, prog);
7305 if (err)
7306 return err;
7307 }
7308
7309 for (i = 0; i < obj->nr_programs; i++) {
7310 prog = &obj->programs[i];
7311 if (prog_is_subprog(obj, prog))
7312 continue;
7313 if (!prog->load) {
7314 pr_debug("prog '%s': skipped loading\n", prog->name);
7315 continue;
7316 }
7317 prog->log_level |= log_level;
7318 err = bpf_program__load(prog, obj->license, obj->kern_version);
7319 if (err)
7320 return err;
7321 }
7322 return 0;
7323 }
7324
7325 static const struct bpf_sec_def *find_sec_def(const char *sec_name);
7326
7327 static struct bpf_object *
__bpf_object__open(const char * path,const void * obj_buf,size_t obj_buf_sz,const struct bpf_object_open_opts * opts)7328 __bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
7329 const struct bpf_object_open_opts *opts)
7330 {
7331 const char *obj_name, *kconfig;
7332 struct bpf_program *prog;
7333 struct bpf_object *obj;
7334 char tmp_name[64];
7335 int err;
7336
7337 if (elf_version(EV_CURRENT) == EV_NONE) {
7338 pr_warn("failed to init libelf for %s\n",
7339 path ? : "(mem buf)");
7340 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
7341 }
7342
7343 if (!OPTS_VALID(opts, bpf_object_open_opts))
7344 return ERR_PTR(-EINVAL);
7345
7346 obj_name = OPTS_GET(opts, object_name, NULL);
7347 if (obj_buf) {
7348 if (!obj_name) {
7349 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
7350 (unsigned long)obj_buf,
7351 (unsigned long)obj_buf_sz);
7352 obj_name = tmp_name;
7353 }
7354 path = obj_name;
7355 pr_debug("loading object '%s' from buffer\n", obj_name);
7356 }
7357
7358 obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
7359 if (IS_ERR(obj))
7360 return obj;
7361
7362 kconfig = OPTS_GET(opts, kconfig, NULL);
7363 if (kconfig) {
7364 obj->kconfig = strdup(kconfig);
7365 if (!obj->kconfig)
7366 return ERR_PTR(-ENOMEM);
7367 }
7368
7369 err = bpf_object__elf_init(obj);
7370 err = err ? : bpf_object__check_endianness(obj);
7371 err = err ? : bpf_object__elf_collect(obj);
7372 err = err ? : bpf_object__collect_externs(obj);
7373 err = err ? : bpf_object__finalize_btf(obj);
7374 err = err ? : bpf_object__init_maps(obj, opts);
7375 err = err ? : bpf_object__collect_relos(obj);
7376 if (err)
7377 goto out;
7378 bpf_object__elf_finish(obj);
7379
7380 bpf_object__for_each_program(prog, obj) {
7381 prog->sec_def = find_sec_def(prog->sec_name);
7382 if (!prog->sec_def) {
7383 /* couldn't guess, but user might manually specify */
7384 pr_debug("prog '%s': unrecognized ELF section name '%s'\n",
7385 prog->name, prog->sec_name);
7386 continue;
7387 }
7388
7389 if (prog->sec_def->is_sleepable)
7390 prog->prog_flags |= BPF_F_SLEEPABLE;
7391 bpf_program__set_type(prog, prog->sec_def->prog_type);
7392 bpf_program__set_expected_attach_type(prog,
7393 prog->sec_def->expected_attach_type);
7394
7395 if (prog->sec_def->prog_type == BPF_PROG_TYPE_TRACING ||
7396 prog->sec_def->prog_type == BPF_PROG_TYPE_EXT)
7397 prog->attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
7398 }
7399
7400 return obj;
7401 out:
7402 bpf_object__close(obj);
7403 return ERR_PTR(err);
7404 }
7405
7406 static struct bpf_object *
__bpf_object__open_xattr(struct bpf_object_open_attr * attr,int flags)7407 __bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags)
7408 {
7409 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
7410 .relaxed_maps = flags & MAPS_RELAX_COMPAT,
7411 );
7412
7413 /* param validation */
7414 if (!attr->file)
7415 return NULL;
7416
7417 pr_debug("loading %s\n", attr->file);
7418 return __bpf_object__open(attr->file, NULL, 0, &opts);
7419 }
7420
bpf_object__open_xattr(struct bpf_object_open_attr * attr)7421 struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
7422 {
7423 return __bpf_object__open_xattr(attr, 0);
7424 }
7425
bpf_object__open(const char * path)7426 struct bpf_object *bpf_object__open(const char *path)
7427 {
7428 struct bpf_object_open_attr attr = {
7429 .file = path,
7430 .prog_type = BPF_PROG_TYPE_UNSPEC,
7431 };
7432
7433 return bpf_object__open_xattr(&attr);
7434 }
7435
7436 struct bpf_object *
bpf_object__open_file(const char * path,const struct bpf_object_open_opts * opts)7437 bpf_object__open_file(const char *path, const struct bpf_object_open_opts *opts)
7438 {
7439 if (!path)
7440 return ERR_PTR(-EINVAL);
7441
7442 pr_debug("loading %s\n", path);
7443
7444 return __bpf_object__open(path, NULL, 0, opts);
7445 }
7446
7447 struct bpf_object *
bpf_object__open_mem(const void * obj_buf,size_t obj_buf_sz,const struct bpf_object_open_opts * opts)7448 bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
7449 const struct bpf_object_open_opts *opts)
7450 {
7451 if (!obj_buf || obj_buf_sz == 0)
7452 return ERR_PTR(-EINVAL);
7453
7454 return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts);
7455 }
7456
7457 struct bpf_object *
bpf_object__open_buffer(const void * obj_buf,size_t obj_buf_sz,const char * name)7458 bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
7459 const char *name)
7460 {
7461 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
7462 .object_name = name,
7463 /* wrong default, but backwards-compatible */
7464 .relaxed_maps = true,
7465 );
7466
7467 /* returning NULL is wrong, but backwards-compatible */
7468 if (!obj_buf || obj_buf_sz == 0)
7469 return NULL;
7470
7471 return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
7472 }
7473
bpf_object__unload(struct bpf_object * obj)7474 int bpf_object__unload(struct bpf_object *obj)
7475 {
7476 size_t i;
7477
7478 if (!obj)
7479 return -EINVAL;
7480
7481 for (i = 0; i < obj->nr_maps; i++) {
7482 zclose(obj->maps[i].fd);
7483 if (obj->maps[i].st_ops)
7484 zfree(&obj->maps[i].st_ops->kern_vdata);
7485 }
7486
7487 for (i = 0; i < obj->nr_programs; i++)
7488 bpf_program__unload(&obj->programs[i]);
7489
7490 return 0;
7491 }
7492
bpf_object__sanitize_maps(struct bpf_object * obj)7493 static int bpf_object__sanitize_maps(struct bpf_object *obj)
7494 {
7495 struct bpf_map *m;
7496
7497 bpf_object__for_each_map(m, obj) {
7498 if (!bpf_map__is_internal(m))
7499 continue;
7500 if (!kernel_supports(FEAT_GLOBAL_DATA)) {
7501 pr_warn("kernel doesn't support global data\n");
7502 return -ENOTSUP;
7503 }
7504 if (!kernel_supports(FEAT_ARRAY_MMAP))
7505 m->def.map_flags ^= BPF_F_MMAPABLE;
7506 }
7507
7508 return 0;
7509 }
7510
bpf_object__read_kallsyms_file(struct bpf_object * obj)7511 static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
7512 {
7513 char sym_type, sym_name[500];
7514 unsigned long long sym_addr;
7515 const struct btf_type *t;
7516 struct extern_desc *ext;
7517 int ret, err = 0;
7518 FILE *f;
7519
7520 f = fopen("/proc/kallsyms", "r");
7521 if (!f) {
7522 err = -errno;
7523 pr_warn("failed to open /proc/kallsyms: %d\n", err);
7524 return err;
7525 }
7526
7527 while (true) {
7528 ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
7529 &sym_addr, &sym_type, sym_name);
7530 if (ret == EOF && feof(f))
7531 break;
7532 if (ret != 3) {
7533 pr_warn("failed to read kallsyms entry: %d\n", ret);
7534 err = -EINVAL;
7535 goto out;
7536 }
7537
7538 ext = find_extern_by_name(obj, sym_name);
7539 if (!ext || ext->type != EXT_KSYM)
7540 continue;
7541
7542 t = btf__type_by_id(obj->btf, ext->btf_id);
7543 if (!btf_is_var(t))
7544 continue;
7545
7546 if (ext->is_set && ext->ksym.addr != sym_addr) {
7547 pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n",
7548 sym_name, ext->ksym.addr, sym_addr);
7549 err = -EINVAL;
7550 goto out;
7551 }
7552 if (!ext->is_set) {
7553 ext->is_set = true;
7554 ext->ksym.addr = sym_addr;
7555 pr_debug("extern (ksym) %s=0x%llx\n", sym_name, sym_addr);
7556 }
7557 }
7558
7559 out:
7560 fclose(f);
7561 return err;
7562 }
7563
find_ksym_btf_id(struct bpf_object * obj,const char * ksym_name,__u16 kind,struct btf ** res_btf,int * res_btf_fd)7564 static int find_ksym_btf_id(struct bpf_object *obj, const char *ksym_name,
7565 __u16 kind, struct btf **res_btf,
7566 int *res_btf_fd)
7567 {
7568 int i, id, btf_fd, err;
7569 struct btf *btf;
7570
7571 btf = obj->btf_vmlinux;
7572 btf_fd = 0;
7573 id = btf__find_by_name_kind(btf, ksym_name, kind);
7574
7575 if (id == -ENOENT) {
7576 err = load_module_btfs(obj);
7577 if (err)
7578 return err;
7579
7580 for (i = 0; i < obj->btf_module_cnt; i++) {
7581 btf = obj->btf_modules[i].btf;
7582 /* we assume module BTF FD is always >0 */
7583 btf_fd = obj->btf_modules[i].fd;
7584 id = btf__find_by_name_kind(btf, ksym_name, kind);
7585 if (id != -ENOENT)
7586 break;
7587 }
7588 }
7589 if (id <= 0) {
7590 pr_warn("extern (%s ksym) '%s': failed to find BTF ID in kernel BTF(s).\n",
7591 __btf_kind_str(kind), ksym_name);
7592 return -ESRCH;
7593 }
7594
7595 *res_btf = btf;
7596 *res_btf_fd = btf_fd;
7597 return id;
7598 }
7599
bpf_object__resolve_ksym_var_btf_id(struct bpf_object * obj,struct extern_desc * ext)7600 static int bpf_object__resolve_ksym_var_btf_id(struct bpf_object *obj,
7601 struct extern_desc *ext)
7602 {
7603 const struct btf_type *targ_var, *targ_type;
7604 __u32 targ_type_id, local_type_id;
7605 const char *targ_var_name;
7606 int id, btf_fd = 0, err;
7607 struct btf *btf = NULL;
7608
7609 id = find_ksym_btf_id(obj, ext->name, BTF_KIND_VAR, &btf, &btf_fd);
7610 if (id < 0)
7611 return id;
7612
7613 /* find local type_id */
7614 local_type_id = ext->ksym.type_id;
7615
7616 /* find target type_id */
7617 targ_var = btf__type_by_id(btf, id);
7618 targ_var_name = btf__name_by_offset(btf, targ_var->name_off);
7619 targ_type = skip_mods_and_typedefs(btf, targ_var->type, &targ_type_id);
7620
7621 err = bpf_core_types_are_compat(obj->btf, local_type_id,
7622 btf, targ_type_id);
7623 if (err <= 0) {
7624 const struct btf_type *local_type;
7625 const char *targ_name, *local_name;
7626
7627 local_type = btf__type_by_id(obj->btf, local_type_id);
7628 local_name = btf__name_by_offset(obj->btf, local_type->name_off);
7629 targ_name = btf__name_by_offset(btf, targ_type->name_off);
7630
7631 pr_warn("extern (var ksym) '%s': incompatible types, expected [%d] %s %s, but kernel has [%d] %s %s\n",
7632 ext->name, local_type_id,
7633 btf_kind_str(local_type), local_name, targ_type_id,
7634 btf_kind_str(targ_type), targ_name);
7635 return -EINVAL;
7636 }
7637
7638 ext->is_set = true;
7639 ext->ksym.kernel_btf_obj_fd = btf_fd;
7640 ext->ksym.kernel_btf_id = id;
7641 pr_debug("extern (var ksym) '%s': resolved to [%d] %s %s\n",
7642 ext->name, id, btf_kind_str(targ_var), targ_var_name);
7643
7644 return 0;
7645 }
7646
bpf_object__resolve_ksym_func_btf_id(struct bpf_object * obj,struct extern_desc * ext)7647 static int bpf_object__resolve_ksym_func_btf_id(struct bpf_object *obj,
7648 struct extern_desc *ext)
7649 {
7650 int local_func_proto_id, kfunc_proto_id, kfunc_id;
7651 const struct btf_type *kern_func;
7652 struct btf *kern_btf = NULL;
7653 int ret, kern_btf_fd = 0;
7654
7655 local_func_proto_id = ext->ksym.type_id;
7656
7657 kfunc_id = find_ksym_btf_id(obj, ext->name, BTF_KIND_FUNC,
7658 &kern_btf, &kern_btf_fd);
7659 if (kfunc_id < 0) {
7660 pr_warn("extern (func ksym) '%s': not found in kernel BTF\n",
7661 ext->name);
7662 return kfunc_id;
7663 }
7664
7665 if (kern_btf != obj->btf_vmlinux) {
7666 pr_warn("extern (func ksym) '%s': function in kernel module is not supported\n",
7667 ext->name);
7668 return -ENOTSUP;
7669 }
7670
7671 kern_func = btf__type_by_id(kern_btf, kfunc_id);
7672 kfunc_proto_id = kern_func->type;
7673
7674 ret = bpf_core_types_are_compat(obj->btf, local_func_proto_id,
7675 kern_btf, kfunc_proto_id);
7676 if (ret <= 0) {
7677 pr_warn("extern (func ksym) '%s': func_proto [%d] incompatible with kernel [%d]\n",
7678 ext->name, local_func_proto_id, kfunc_proto_id);
7679 return -EINVAL;
7680 }
7681
7682 ext->is_set = true;
7683 ext->ksym.kernel_btf_obj_fd = kern_btf_fd;
7684 ext->ksym.kernel_btf_id = kfunc_id;
7685 pr_debug("extern (func ksym) '%s': resolved to kernel [%d]\n",
7686 ext->name, kfunc_id);
7687
7688 return 0;
7689 }
7690
bpf_object__resolve_ksyms_btf_id(struct bpf_object * obj)7691 static int bpf_object__resolve_ksyms_btf_id(struct bpf_object *obj)
7692 {
7693 const struct btf_type *t;
7694 struct extern_desc *ext;
7695 int i, err;
7696
7697 for (i = 0; i < obj->nr_extern; i++) {
7698 ext = &obj->externs[i];
7699 if (ext->type != EXT_KSYM || !ext->ksym.type_id)
7700 continue;
7701
7702 t = btf__type_by_id(obj->btf, ext->btf_id);
7703 if (btf_is_var(t))
7704 err = bpf_object__resolve_ksym_var_btf_id(obj, ext);
7705 else
7706 err = bpf_object__resolve_ksym_func_btf_id(obj, ext);
7707 if (err)
7708 return err;
7709 }
7710 return 0;
7711 }
7712
bpf_object__resolve_externs(struct bpf_object * obj,const char * extra_kconfig)7713 static int bpf_object__resolve_externs(struct bpf_object *obj,
7714 const char *extra_kconfig)
7715 {
7716 bool need_config = false, need_kallsyms = false;
7717 bool need_vmlinux_btf = false;
7718 struct extern_desc *ext;
7719 void *kcfg_data = NULL;
7720 int err, i;
7721
7722 if (obj->nr_extern == 0)
7723 return 0;
7724
7725 if (obj->kconfig_map_idx >= 0)
7726 kcfg_data = obj->maps[obj->kconfig_map_idx].mmaped;
7727
7728 for (i = 0; i < obj->nr_extern; i++) {
7729 ext = &obj->externs[i];
7730
7731 if (ext->type == EXT_KCFG &&
7732 strcmp(ext->name, "LINUX_KERNEL_VERSION") == 0) {
7733 void *ext_val = kcfg_data + ext->kcfg.data_off;
7734 __u32 kver = get_kernel_version();
7735
7736 if (!kver) {
7737 pr_warn("failed to get kernel version\n");
7738 return -EINVAL;
7739 }
7740 err = set_kcfg_value_num(ext, ext_val, kver);
7741 if (err)
7742 return err;
7743 pr_debug("extern (kcfg) %s=0x%x\n", ext->name, kver);
7744 } else if (ext->type == EXT_KCFG &&
7745 strncmp(ext->name, "CONFIG_", 7) == 0) {
7746 need_config = true;
7747 } else if (ext->type == EXT_KSYM) {
7748 if (ext->ksym.type_id)
7749 need_vmlinux_btf = true;
7750 else
7751 need_kallsyms = true;
7752 } else {
7753 pr_warn("unrecognized extern '%s'\n", ext->name);
7754 return -EINVAL;
7755 }
7756 }
7757 if (need_config && extra_kconfig) {
7758 err = bpf_object__read_kconfig_mem(obj, extra_kconfig, kcfg_data);
7759 if (err)
7760 return -EINVAL;
7761 need_config = false;
7762 for (i = 0; i < obj->nr_extern; i++) {
7763 ext = &obj->externs[i];
7764 if (ext->type == EXT_KCFG && !ext->is_set) {
7765 need_config = true;
7766 break;
7767 }
7768 }
7769 }
7770 if (need_config) {
7771 err = bpf_object__read_kconfig_file(obj, kcfg_data);
7772 if (err)
7773 return -EINVAL;
7774 }
7775 if (need_kallsyms) {
7776 err = bpf_object__read_kallsyms_file(obj);
7777 if (err)
7778 return -EINVAL;
7779 }
7780 if (need_vmlinux_btf) {
7781 err = bpf_object__resolve_ksyms_btf_id(obj);
7782 if (err)
7783 return -EINVAL;
7784 }
7785 for (i = 0; i < obj->nr_extern; i++) {
7786 ext = &obj->externs[i];
7787
7788 if (!ext->is_set && !ext->is_weak) {
7789 pr_warn("extern %s (strong) not resolved\n", ext->name);
7790 return -ESRCH;
7791 } else if (!ext->is_set) {
7792 pr_debug("extern %s (weak) not resolved, defaulting to zero\n",
7793 ext->name);
7794 }
7795 }
7796
7797 return 0;
7798 }
7799
bpf_object__load_xattr(struct bpf_object_load_attr * attr)7800 int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
7801 {
7802 struct bpf_object *obj;
7803 int err, i;
7804
7805 if (!attr)
7806 return -EINVAL;
7807 obj = attr->obj;
7808 if (!obj)
7809 return -EINVAL;
7810
7811 if (obj->loaded) {
7812 pr_warn("object '%s': load can't be attempted twice\n", obj->name);
7813 return -EINVAL;
7814 }
7815
7816 err = bpf_object__probe_loading(obj);
7817 err = err ? : bpf_object__load_vmlinux_btf(obj, false);
7818 err = err ? : bpf_object__resolve_externs(obj, obj->kconfig);
7819 err = err ? : bpf_object__sanitize_and_load_btf(obj);
7820 err = err ? : bpf_object__sanitize_maps(obj);
7821 err = err ? : bpf_object__init_kern_struct_ops_maps(obj);
7822 err = err ? : bpf_object__create_maps(obj);
7823 err = err ? : bpf_object__relocate(obj, attr->target_btf_path);
7824 err = err ? : bpf_object__load_progs(obj, attr->log_level);
7825
7826 /* clean up module BTFs */
7827 for (i = 0; i < obj->btf_module_cnt; i++) {
7828 close(obj->btf_modules[i].fd);
7829 btf__free(obj->btf_modules[i].btf);
7830 free(obj->btf_modules[i].name);
7831 }
7832 free(obj->btf_modules);
7833
7834 /* clean up vmlinux BTF */
7835 btf__free(obj->btf_vmlinux);
7836 obj->btf_vmlinux = NULL;
7837
7838 obj->loaded = true; /* doesn't matter if successfully or not */
7839
7840 if (err)
7841 goto out;
7842
7843 return 0;
7844 out:
7845 /* unpin any maps that were auto-pinned during load */
7846 for (i = 0; i < obj->nr_maps; i++)
7847 if (obj->maps[i].pinned && !obj->maps[i].reused)
7848 bpf_map__unpin(&obj->maps[i], NULL);
7849
7850 bpf_object__unload(obj);
7851 pr_warn("failed to load object '%s'\n", obj->path);
7852 return err;
7853 }
7854
bpf_object__load(struct bpf_object * obj)7855 int bpf_object__load(struct bpf_object *obj)
7856 {
7857 struct bpf_object_load_attr attr = {
7858 .obj = obj,
7859 };
7860
7861 return bpf_object__load_xattr(&attr);
7862 }
7863
make_parent_dir(const char * path)7864 static int make_parent_dir(const char *path)
7865 {
7866 char *cp, errmsg[STRERR_BUFSIZE];
7867 char *dname, *dir;
7868 int err = 0;
7869
7870 dname = strdup(path);
7871 if (dname == NULL)
7872 return -ENOMEM;
7873
7874 dir = dirname(dname);
7875 if (mkdir(dir, 0700) && errno != EEXIST)
7876 err = -errno;
7877
7878 free(dname);
7879 if (err) {
7880 cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
7881 pr_warn("failed to mkdir %s: %s\n", path, cp);
7882 }
7883 return err;
7884 }
7885
check_path(const char * path)7886 static int check_path(const char *path)
7887 {
7888 char *cp, errmsg[STRERR_BUFSIZE];
7889 struct statfs st_fs;
7890 char *dname, *dir;
7891 int err = 0;
7892
7893 if (path == NULL)
7894 return -EINVAL;
7895
7896 dname = strdup(path);
7897 if (dname == NULL)
7898 return -ENOMEM;
7899
7900 dir = dirname(dname);
7901 if (statfs(dir, &st_fs)) {
7902 cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
7903 pr_warn("failed to statfs %s: %s\n", dir, cp);
7904 err = -errno;
7905 }
7906 free(dname);
7907
7908 if (!err && st_fs.f_type != BPF_FS_MAGIC) {
7909 pr_warn("specified path %s is not on BPF FS\n", path);
7910 err = -EINVAL;
7911 }
7912
7913 return err;
7914 }
7915
bpf_program__pin_instance(struct bpf_program * prog,const char * path,int instance)7916 int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
7917 int instance)
7918 {
7919 char *cp, errmsg[STRERR_BUFSIZE];
7920 int err;
7921
7922 err = make_parent_dir(path);
7923 if (err)
7924 return err;
7925
7926 err = check_path(path);
7927 if (err)
7928 return err;
7929
7930 if (prog == NULL) {
7931 pr_warn("invalid program pointer\n");
7932 return -EINVAL;
7933 }
7934
7935 if (instance < 0 || instance >= prog->instances.nr) {
7936 pr_warn("invalid prog instance %d of prog %s (max %d)\n",
7937 instance, prog->name, prog->instances.nr);
7938 return -EINVAL;
7939 }
7940
7941 if (bpf_obj_pin(prog->instances.fds[instance], path)) {
7942 err = -errno;
7943 cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
7944 pr_warn("failed to pin program: %s\n", cp);
7945 return err;
7946 }
7947 pr_debug("pinned program '%s'\n", path);
7948
7949 return 0;
7950 }
7951
bpf_program__unpin_instance(struct bpf_program * prog,const char * path,int instance)7952 int bpf_program__unpin_instance(struct bpf_program *prog, const char *path,
7953 int instance)
7954 {
7955 int err;
7956
7957 err = check_path(path);
7958 if (err)
7959 return err;
7960
7961 if (prog == NULL) {
7962 pr_warn("invalid program pointer\n");
7963 return -EINVAL;
7964 }
7965
7966 if (instance < 0 || instance >= prog->instances.nr) {
7967 pr_warn("invalid prog instance %d of prog %s (max %d)\n",
7968 instance, prog->name, prog->instances.nr);
7969 return -EINVAL;
7970 }
7971
7972 err = unlink(path);
7973 if (err != 0)
7974 return -errno;
7975 pr_debug("unpinned program '%s'\n", path);
7976
7977 return 0;
7978 }
7979
bpf_program__pin(struct bpf_program * prog,const char * path)7980 int bpf_program__pin(struct bpf_program *prog, const char *path)
7981 {
7982 int i, err;
7983
7984 err = make_parent_dir(path);
7985 if (err)
7986 return err;
7987
7988 err = check_path(path);
7989 if (err)
7990 return err;
7991
7992 if (prog == NULL) {
7993 pr_warn("invalid program pointer\n");
7994 return -EINVAL;
7995 }
7996
7997 if (prog->instances.nr <= 0) {
7998 pr_warn("no instances of prog %s to pin\n", prog->name);
7999 return -EINVAL;
8000 }
8001
8002 if (prog->instances.nr == 1) {
8003 /* don't create subdirs when pinning single instance */
8004 return bpf_program__pin_instance(prog, path, 0);
8005 }
8006
8007 for (i = 0; i < prog->instances.nr; i++) {
8008 char buf[PATH_MAX];
8009 int len;
8010
8011 len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
8012 if (len < 0) {
8013 err = -EINVAL;
8014 goto err_unpin;
8015 } else if (len >= PATH_MAX) {
8016 err = -ENAMETOOLONG;
8017 goto err_unpin;
8018 }
8019
8020 err = bpf_program__pin_instance(prog, buf, i);
8021 if (err)
8022 goto err_unpin;
8023 }
8024
8025 return 0;
8026
8027 err_unpin:
8028 for (i = i - 1; i >= 0; i--) {
8029 char buf[PATH_MAX];
8030 int len;
8031
8032 len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
8033 if (len < 0)
8034 continue;
8035 else if (len >= PATH_MAX)
8036 continue;
8037
8038 bpf_program__unpin_instance(prog, buf, i);
8039 }
8040
8041 rmdir(path);
8042
8043 return err;
8044 }
8045
bpf_program__unpin(struct bpf_program * prog,const char * path)8046 int bpf_program__unpin(struct bpf_program *prog, const char *path)
8047 {
8048 int i, err;
8049
8050 err = check_path(path);
8051 if (err)
8052 return err;
8053
8054 if (prog == NULL) {
8055 pr_warn("invalid program pointer\n");
8056 return -EINVAL;
8057 }
8058
8059 if (prog->instances.nr <= 0) {
8060 pr_warn("no instances of prog %s to pin\n", prog->name);
8061 return -EINVAL;
8062 }
8063
8064 if (prog->instances.nr == 1) {
8065 /* don't create subdirs when pinning single instance */
8066 return bpf_program__unpin_instance(prog, path, 0);
8067 }
8068
8069 for (i = 0; i < prog->instances.nr; i++) {
8070 char buf[PATH_MAX];
8071 int len;
8072
8073 len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
8074 if (len < 0)
8075 return -EINVAL;
8076 else if (len >= PATH_MAX)
8077 return -ENAMETOOLONG;
8078
8079 err = bpf_program__unpin_instance(prog, buf, i);
8080 if (err)
8081 return err;
8082 }
8083
8084 err = rmdir(path);
8085 if (err)
8086 return -errno;
8087
8088 return 0;
8089 }
8090
bpf_map__pin(struct bpf_map * map,const char * path)8091 int bpf_map__pin(struct bpf_map *map, const char *path)
8092 {
8093 char *cp, errmsg[STRERR_BUFSIZE];
8094 int err;
8095
8096 if (map == NULL) {
8097 pr_warn("invalid map pointer\n");
8098 return -EINVAL;
8099 }
8100
8101 if (map->pin_path) {
8102 if (path && strcmp(path, map->pin_path)) {
8103 pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
8104 bpf_map__name(map), map->pin_path, path);
8105 return -EINVAL;
8106 } else if (map->pinned) {
8107 pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
8108 bpf_map__name(map), map->pin_path);
8109 return 0;
8110 }
8111 } else {
8112 if (!path) {
8113 pr_warn("missing a path to pin map '%s' at\n",
8114 bpf_map__name(map));
8115 return -EINVAL;
8116 } else if (map->pinned) {
8117 pr_warn("map '%s' already pinned\n", bpf_map__name(map));
8118 return -EEXIST;
8119 }
8120
8121 map->pin_path = strdup(path);
8122 if (!map->pin_path) {
8123 err = -errno;
8124 goto out_err;
8125 }
8126 }
8127
8128 err = make_parent_dir(map->pin_path);
8129 if (err)
8130 return err;
8131
8132 err = check_path(map->pin_path);
8133 if (err)
8134 return err;
8135
8136 if (bpf_obj_pin(map->fd, map->pin_path)) {
8137 err = -errno;
8138 goto out_err;
8139 }
8140
8141 map->pinned = true;
8142 pr_debug("pinned map '%s'\n", map->pin_path);
8143
8144 return 0;
8145
8146 out_err:
8147 cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
8148 pr_warn("failed to pin map: %s\n", cp);
8149 return err;
8150 }
8151
bpf_map__unpin(struct bpf_map * map,const char * path)8152 int bpf_map__unpin(struct bpf_map *map, const char *path)
8153 {
8154 int err;
8155
8156 if (map == NULL) {
8157 pr_warn("invalid map pointer\n");
8158 return -EINVAL;
8159 }
8160
8161 if (map->pin_path) {
8162 if (path && strcmp(path, map->pin_path)) {
8163 pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
8164 bpf_map__name(map), map->pin_path, path);
8165 return -EINVAL;
8166 }
8167 path = map->pin_path;
8168 } else if (!path) {
8169 pr_warn("no path to unpin map '%s' from\n",
8170 bpf_map__name(map));
8171 return -EINVAL;
8172 }
8173
8174 err = check_path(path);
8175 if (err)
8176 return err;
8177
8178 err = unlink(path);
8179 if (err != 0)
8180 return -errno;
8181
8182 map->pinned = false;
8183 pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
8184
8185 return 0;
8186 }
8187
bpf_map__set_pin_path(struct bpf_map * map,const char * path)8188 int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
8189 {
8190 char *new = NULL;
8191
8192 if (path) {
8193 new = strdup(path);
8194 if (!new)
8195 return -errno;
8196 }
8197
8198 free(map->pin_path);
8199 map->pin_path = new;
8200 return 0;
8201 }
8202
bpf_map__get_pin_path(const struct bpf_map * map)8203 const char *bpf_map__get_pin_path(const struct bpf_map *map)
8204 {
8205 return map->pin_path;
8206 }
8207
bpf_map__is_pinned(const struct bpf_map * map)8208 bool bpf_map__is_pinned(const struct bpf_map *map)
8209 {
8210 return map->pinned;
8211 }
8212
sanitize_pin_path(char * s)8213 static void sanitize_pin_path(char *s)
8214 {
8215 /* bpffs disallows periods in path names */
8216 while (*s) {
8217 if (*s == '.')
8218 *s = '_';
8219 s++;
8220 }
8221 }
8222
bpf_object__pin_maps(struct bpf_object * obj,const char * path)8223 int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
8224 {
8225 struct bpf_map *map;
8226 int err;
8227
8228 if (!obj)
8229 return -ENOENT;
8230
8231 if (!obj->loaded) {
8232 pr_warn("object not yet loaded; load it first\n");
8233 return -ENOENT;
8234 }
8235
8236 bpf_object__for_each_map(map, obj) {
8237 char *pin_path = NULL;
8238 char buf[PATH_MAX];
8239
8240 if (path) {
8241 int len;
8242
8243 len = snprintf(buf, PATH_MAX, "%s/%s", path,
8244 bpf_map__name(map));
8245 if (len < 0) {
8246 err = -EINVAL;
8247 goto err_unpin_maps;
8248 } else if (len >= PATH_MAX) {
8249 err = -ENAMETOOLONG;
8250 goto err_unpin_maps;
8251 }
8252 sanitize_pin_path(buf);
8253 pin_path = buf;
8254 } else if (!map->pin_path) {
8255 continue;
8256 }
8257
8258 err = bpf_map__pin(map, pin_path);
8259 if (err)
8260 goto err_unpin_maps;
8261 }
8262
8263 return 0;
8264
8265 err_unpin_maps:
8266 while ((map = bpf_map__prev(map, obj))) {
8267 if (!map->pin_path)
8268 continue;
8269
8270 bpf_map__unpin(map, NULL);
8271 }
8272
8273 return err;
8274 }
8275
bpf_object__unpin_maps(struct bpf_object * obj,const char * path)8276 int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
8277 {
8278 struct bpf_map *map;
8279 int err;
8280
8281 if (!obj)
8282 return -ENOENT;
8283
8284 bpf_object__for_each_map(map, obj) {
8285 char *pin_path = NULL;
8286 char buf[PATH_MAX];
8287
8288 if (path) {
8289 int len;
8290
8291 len = snprintf(buf, PATH_MAX, "%s/%s", path,
8292 bpf_map__name(map));
8293 if (len < 0)
8294 return -EINVAL;
8295 else if (len >= PATH_MAX)
8296 return -ENAMETOOLONG;
8297 sanitize_pin_path(buf);
8298 pin_path = buf;
8299 } else if (!map->pin_path) {
8300 continue;
8301 }
8302
8303 err = bpf_map__unpin(map, pin_path);
8304 if (err)
8305 return err;
8306 }
8307
8308 return 0;
8309 }
8310
bpf_object__pin_programs(struct bpf_object * obj,const char * path)8311 int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
8312 {
8313 struct bpf_program *prog;
8314 int err;
8315
8316 if (!obj)
8317 return -ENOENT;
8318
8319 if (!obj->loaded) {
8320 pr_warn("object not yet loaded; load it first\n");
8321 return -ENOENT;
8322 }
8323
8324 bpf_object__for_each_program(prog, obj) {
8325 char buf[PATH_MAX];
8326 int len;
8327
8328 len = snprintf(buf, PATH_MAX, "%s/%s", path,
8329 prog->pin_name);
8330 if (len < 0) {
8331 err = -EINVAL;
8332 goto err_unpin_programs;
8333 } else if (len >= PATH_MAX) {
8334 err = -ENAMETOOLONG;
8335 goto err_unpin_programs;
8336 }
8337
8338 err = bpf_program__pin(prog, buf);
8339 if (err)
8340 goto err_unpin_programs;
8341 }
8342
8343 return 0;
8344
8345 err_unpin_programs:
8346 while ((prog = bpf_program__prev(prog, obj))) {
8347 char buf[PATH_MAX];
8348 int len;
8349
8350 len = snprintf(buf, PATH_MAX, "%s/%s", path,
8351 prog->pin_name);
8352 if (len < 0)
8353 continue;
8354 else if (len >= PATH_MAX)
8355 continue;
8356
8357 bpf_program__unpin(prog, buf);
8358 }
8359
8360 return err;
8361 }
8362
bpf_object__unpin_programs(struct bpf_object * obj,const char * path)8363 int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
8364 {
8365 struct bpf_program *prog;
8366 int err;
8367
8368 if (!obj)
8369 return -ENOENT;
8370
8371 bpf_object__for_each_program(prog, obj) {
8372 char buf[PATH_MAX];
8373 int len;
8374
8375 len = snprintf(buf, PATH_MAX, "%s/%s", path,
8376 prog->pin_name);
8377 if (len < 0)
8378 return -EINVAL;
8379 else if (len >= PATH_MAX)
8380 return -ENAMETOOLONG;
8381
8382 err = bpf_program__unpin(prog, buf);
8383 if (err)
8384 return err;
8385 }
8386
8387 return 0;
8388 }
8389
bpf_object__pin(struct bpf_object * obj,const char * path)8390 int bpf_object__pin(struct bpf_object *obj, const char *path)
8391 {
8392 int err;
8393
8394 err = bpf_object__pin_maps(obj, path);
8395 if (err)
8396 return err;
8397
8398 err = bpf_object__pin_programs(obj, path);
8399 if (err) {
8400 bpf_object__unpin_maps(obj, path);
8401 return err;
8402 }
8403
8404 return 0;
8405 }
8406
bpf_map__destroy(struct bpf_map * map)8407 static void bpf_map__destroy(struct bpf_map *map)
8408 {
8409 if (map->clear_priv)
8410 map->clear_priv(map, map->priv);
8411 map->priv = NULL;
8412 map->clear_priv = NULL;
8413
8414 if (map->inner_map) {
8415 bpf_map__destroy(map->inner_map);
8416 zfree(&map->inner_map);
8417 }
8418
8419 zfree(&map->init_slots);
8420 map->init_slots_sz = 0;
8421
8422 if (map->mmaped) {
8423 munmap(map->mmaped, bpf_map_mmap_sz(map));
8424 map->mmaped = NULL;
8425 }
8426
8427 if (map->st_ops) {
8428 zfree(&map->st_ops->data);
8429 zfree(&map->st_ops->progs);
8430 zfree(&map->st_ops->kern_func_off);
8431 zfree(&map->st_ops);
8432 }
8433
8434 zfree(&map->name);
8435 zfree(&map->pin_path);
8436
8437 if (map->fd >= 0)
8438 zclose(map->fd);
8439 }
8440
bpf_object__close(struct bpf_object * obj)8441 void bpf_object__close(struct bpf_object *obj)
8442 {
8443 size_t i;
8444
8445 if (IS_ERR_OR_NULL(obj))
8446 return;
8447
8448 if (obj->clear_priv)
8449 obj->clear_priv(obj, obj->priv);
8450
8451 bpf_object__elf_finish(obj);
8452 bpf_object__unload(obj);
8453 btf__free(obj->btf);
8454 btf_ext__free(obj->btf_ext);
8455
8456 for (i = 0; i < obj->nr_maps; i++)
8457 bpf_map__destroy(&obj->maps[i]);
8458
8459 zfree(&obj->kconfig);
8460 zfree(&obj->externs);
8461 obj->nr_extern = 0;
8462
8463 zfree(&obj->maps);
8464 obj->nr_maps = 0;
8465
8466 if (obj->programs && obj->nr_programs) {
8467 for (i = 0; i < obj->nr_programs; i++)
8468 bpf_program__exit(&obj->programs[i]);
8469 }
8470 zfree(&obj->programs);
8471
8472 list_del(&obj->list);
8473 free(obj);
8474 }
8475
8476 struct bpf_object *
bpf_object__next(struct bpf_object * prev)8477 bpf_object__next(struct bpf_object *prev)
8478 {
8479 struct bpf_object *next;
8480
8481 if (!prev)
8482 next = list_first_entry(&bpf_objects_list,
8483 struct bpf_object,
8484 list);
8485 else
8486 next = list_next_entry(prev, list);
8487
8488 /* Empty list is noticed here so don't need checking on entry. */
8489 if (&next->list == &bpf_objects_list)
8490 return NULL;
8491
8492 return next;
8493 }
8494
bpf_object__name(const struct bpf_object * obj)8495 const char *bpf_object__name(const struct bpf_object *obj)
8496 {
8497 return obj ? obj->name : ERR_PTR(-EINVAL);
8498 }
8499
bpf_object__kversion(const struct bpf_object * obj)8500 unsigned int bpf_object__kversion(const struct bpf_object *obj)
8501 {
8502 return obj ? obj->kern_version : 0;
8503 }
8504
bpf_object__btf(const struct bpf_object * obj)8505 struct btf *bpf_object__btf(const struct bpf_object *obj)
8506 {
8507 return obj ? obj->btf : NULL;
8508 }
8509
bpf_object__btf_fd(const struct bpf_object * obj)8510 int bpf_object__btf_fd(const struct bpf_object *obj)
8511 {
8512 return obj->btf ? btf__fd(obj->btf) : -1;
8513 }
8514
bpf_object__set_kversion(struct bpf_object * obj,__u32 kern_version)8515 int bpf_object__set_kversion(struct bpf_object *obj, __u32 kern_version)
8516 {
8517 if (obj->loaded)
8518 return -EINVAL;
8519
8520 obj->kern_version = kern_version;
8521
8522 return 0;
8523 }
8524
bpf_object__set_priv(struct bpf_object * obj,void * priv,bpf_object_clear_priv_t clear_priv)8525 int bpf_object__set_priv(struct bpf_object *obj, void *priv,
8526 bpf_object_clear_priv_t clear_priv)
8527 {
8528 if (obj->priv && obj->clear_priv)
8529 obj->clear_priv(obj, obj->priv);
8530
8531 obj->priv = priv;
8532 obj->clear_priv = clear_priv;
8533 return 0;
8534 }
8535
bpf_object__priv(const struct bpf_object * obj)8536 void *bpf_object__priv(const struct bpf_object *obj)
8537 {
8538 return obj ? obj->priv : ERR_PTR(-EINVAL);
8539 }
8540
8541 static struct bpf_program *
__bpf_program__iter(const struct bpf_program * p,const struct bpf_object * obj,bool forward)8542 __bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
8543 bool forward)
8544 {
8545 size_t nr_programs = obj->nr_programs;
8546 ssize_t idx;
8547
8548 if (!nr_programs)
8549 return NULL;
8550
8551 if (!p)
8552 /* Iter from the beginning */
8553 return forward ? &obj->programs[0] :
8554 &obj->programs[nr_programs - 1];
8555
8556 if (p->obj != obj) {
8557 pr_warn("error: program handler doesn't match object\n");
8558 return NULL;
8559 }
8560
8561 idx = (p - obj->programs) + (forward ? 1 : -1);
8562 if (idx >= obj->nr_programs || idx < 0)
8563 return NULL;
8564 return &obj->programs[idx];
8565 }
8566
8567 struct bpf_program *
bpf_program__next(struct bpf_program * prev,const struct bpf_object * obj)8568 bpf_program__next(struct bpf_program *prev, const struct bpf_object *obj)
8569 {
8570 struct bpf_program *prog = prev;
8571
8572 do {
8573 prog = __bpf_program__iter(prog, obj, true);
8574 } while (prog && prog_is_subprog(obj, prog));
8575
8576 return prog;
8577 }
8578
8579 struct bpf_program *
bpf_program__prev(struct bpf_program * next,const struct bpf_object * obj)8580 bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj)
8581 {
8582 struct bpf_program *prog = next;
8583
8584 do {
8585 prog = __bpf_program__iter(prog, obj, false);
8586 } while (prog && prog_is_subprog(obj, prog));
8587
8588 return prog;
8589 }
8590
bpf_program__set_priv(struct bpf_program * prog,void * priv,bpf_program_clear_priv_t clear_priv)8591 int bpf_program__set_priv(struct bpf_program *prog, void *priv,
8592 bpf_program_clear_priv_t clear_priv)
8593 {
8594 if (prog->priv && prog->clear_priv)
8595 prog->clear_priv(prog, prog->priv);
8596
8597 prog->priv = priv;
8598 prog->clear_priv = clear_priv;
8599 return 0;
8600 }
8601
bpf_program__priv(const struct bpf_program * prog)8602 void *bpf_program__priv(const struct bpf_program *prog)
8603 {
8604 return prog ? prog->priv : ERR_PTR(-EINVAL);
8605 }
8606
bpf_program__set_ifindex(struct bpf_program * prog,__u32 ifindex)8607 void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
8608 {
8609 prog->prog_ifindex = ifindex;
8610 }
8611
bpf_program__name(const struct bpf_program * prog)8612 const char *bpf_program__name(const struct bpf_program *prog)
8613 {
8614 return prog->name;
8615 }
8616
bpf_program__section_name(const struct bpf_program * prog)8617 const char *bpf_program__section_name(const struct bpf_program *prog)
8618 {
8619 return prog->sec_name;
8620 }
8621
bpf_program__title(const struct bpf_program * prog,bool needs_copy)8622 const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
8623 {
8624 const char *title;
8625
8626 title = prog->sec_name;
8627 if (needs_copy) {
8628 title = strdup(title);
8629 if (!title) {
8630 pr_warn("failed to strdup program title\n");
8631 return ERR_PTR(-ENOMEM);
8632 }
8633 }
8634
8635 return title;
8636 }
8637
bpf_program__autoload(const struct bpf_program * prog)8638 bool bpf_program__autoload(const struct bpf_program *prog)
8639 {
8640 return prog->load;
8641 }
8642
bpf_program__set_autoload(struct bpf_program * prog,bool autoload)8643 int bpf_program__set_autoload(struct bpf_program *prog, bool autoload)
8644 {
8645 if (prog->obj->loaded)
8646 return -EINVAL;
8647
8648 prog->load = autoload;
8649 return 0;
8650 }
8651
bpf_program__fd(const struct bpf_program * prog)8652 int bpf_program__fd(const struct bpf_program *prog)
8653 {
8654 return bpf_program__nth_fd(prog, 0);
8655 }
8656
bpf_program__size(const struct bpf_program * prog)8657 size_t bpf_program__size(const struct bpf_program *prog)
8658 {
8659 return prog->insns_cnt * BPF_INSN_SZ;
8660 }
8661
bpf_program__set_prep(struct bpf_program * prog,int nr_instances,bpf_program_prep_t prep)8662 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
8663 bpf_program_prep_t prep)
8664 {
8665 int *instances_fds;
8666
8667 if (nr_instances <= 0 || !prep)
8668 return -EINVAL;
8669
8670 if (prog->instances.nr > 0 || prog->instances.fds) {
8671 pr_warn("Can't set pre-processor after loading\n");
8672 return -EINVAL;
8673 }
8674
8675 instances_fds = malloc(sizeof(int) * nr_instances);
8676 if (!instances_fds) {
8677 pr_warn("alloc memory failed for fds\n");
8678 return -ENOMEM;
8679 }
8680
8681 /* fill all fd with -1 */
8682 memset(instances_fds, -1, sizeof(int) * nr_instances);
8683
8684 prog->instances.nr = nr_instances;
8685 prog->instances.fds = instances_fds;
8686 prog->preprocessor = prep;
8687 return 0;
8688 }
8689
bpf_program__nth_fd(const struct bpf_program * prog,int n)8690 int bpf_program__nth_fd(const struct bpf_program *prog, int n)
8691 {
8692 int fd;
8693
8694 if (!prog)
8695 return -EINVAL;
8696
8697 if (n >= prog->instances.nr || n < 0) {
8698 pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
8699 n, prog->name, prog->instances.nr);
8700 return -EINVAL;
8701 }
8702
8703 fd = prog->instances.fds[n];
8704 if (fd < 0) {
8705 pr_warn("%dth instance of program '%s' is invalid\n",
8706 n, prog->name);
8707 return -ENOENT;
8708 }
8709
8710 return fd;
8711 }
8712
bpf_program__get_type(const struct bpf_program * prog)8713 enum bpf_prog_type bpf_program__get_type(const struct bpf_program *prog)
8714 {
8715 return prog->type;
8716 }
8717
bpf_program__set_type(struct bpf_program * prog,enum bpf_prog_type type)8718 void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
8719 {
8720 prog->type = type;
8721 }
8722
bpf_program__is_type(const struct bpf_program * prog,enum bpf_prog_type type)8723 static bool bpf_program__is_type(const struct bpf_program *prog,
8724 enum bpf_prog_type type)
8725 {
8726 return prog ? (prog->type == type) : false;
8727 }
8728
8729 #define BPF_PROG_TYPE_FNS(NAME, TYPE) \
8730 int bpf_program__set_##NAME(struct bpf_program *prog) \
8731 { \
8732 if (!prog) \
8733 return -EINVAL; \
8734 bpf_program__set_type(prog, TYPE); \
8735 return 0; \
8736 } \
8737 \
8738 bool bpf_program__is_##NAME(const struct bpf_program *prog) \
8739 { \
8740 return bpf_program__is_type(prog, TYPE); \
8741 } \
8742
8743 BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER);
8744 BPF_PROG_TYPE_FNS(lsm, BPF_PROG_TYPE_LSM);
8745 BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE);
8746 BPF_PROG_TYPE_FNS(sched_cls, BPF_PROG_TYPE_SCHED_CLS);
8747 BPF_PROG_TYPE_FNS(sched_act, BPF_PROG_TYPE_SCHED_ACT);
8748 BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT);
8749 BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT);
8750 BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
8751 BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
8752 BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
8753 BPF_PROG_TYPE_FNS(struct_ops, BPF_PROG_TYPE_STRUCT_OPS);
8754 BPF_PROG_TYPE_FNS(extension, BPF_PROG_TYPE_EXT);
8755 BPF_PROG_TYPE_FNS(sk_lookup, BPF_PROG_TYPE_SK_LOOKUP);
8756
8757 enum bpf_attach_type
bpf_program__get_expected_attach_type(const struct bpf_program * prog)8758 bpf_program__get_expected_attach_type(const struct bpf_program *prog)
8759 {
8760 return prog->expected_attach_type;
8761 }
8762
bpf_program__set_expected_attach_type(struct bpf_program * prog,enum bpf_attach_type type)8763 void bpf_program__set_expected_attach_type(struct bpf_program *prog,
8764 enum bpf_attach_type type)
8765 {
8766 prog->expected_attach_type = type;
8767 }
8768
8769 #define BPF_PROG_SEC_IMPL(string, ptype, eatype, eatype_optional, \
8770 attachable, attach_btf) \
8771 { \
8772 .sec = string, \
8773 .len = sizeof(string) - 1, \
8774 .prog_type = ptype, \
8775 .expected_attach_type = eatype, \
8776 .is_exp_attach_type_optional = eatype_optional, \
8777 .is_attachable = attachable, \
8778 .is_attach_btf = attach_btf, \
8779 }
8780
8781 /* Programs that can NOT be attached. */
8782 #define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0, 0)
8783
8784 /* Programs that can be attached. */
8785 #define BPF_APROG_SEC(string, ptype, atype) \
8786 BPF_PROG_SEC_IMPL(string, ptype, atype, true, 1, 0)
8787
8788 /* Programs that must specify expected attach type at load time. */
8789 #define BPF_EAPROG_SEC(string, ptype, eatype) \
8790 BPF_PROG_SEC_IMPL(string, ptype, eatype, false, 1, 0)
8791
8792 /* Programs that use BTF to identify attach point */
8793 #define BPF_PROG_BTF(string, ptype, eatype) \
8794 BPF_PROG_SEC_IMPL(string, ptype, eatype, false, 0, 1)
8795
8796 /* Programs that can be attached but attach type can't be identified by section
8797 * name. Kept for backward compatibility.
8798 */
8799 #define BPF_APROG_COMPAT(string, ptype) BPF_PROG_SEC(string, ptype)
8800
8801 #define SEC_DEF(sec_pfx, ptype, ...) { \
8802 .sec = sec_pfx, \
8803 .len = sizeof(sec_pfx) - 1, \
8804 .prog_type = BPF_PROG_TYPE_##ptype, \
8805 __VA_ARGS__ \
8806 }
8807
8808 static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
8809 struct bpf_program *prog);
8810 static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
8811 struct bpf_program *prog);
8812 static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
8813 struct bpf_program *prog);
8814 static struct bpf_link *attach_trace(const struct bpf_sec_def *sec,
8815 struct bpf_program *prog);
8816 static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
8817 struct bpf_program *prog);
8818 static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
8819 struct bpf_program *prog);
8820
8821 static const struct bpf_sec_def section_defs[] = {
8822 BPF_PROG_SEC("socket", BPF_PROG_TYPE_SOCKET_FILTER),
8823 BPF_PROG_SEC("sk_reuseport", BPF_PROG_TYPE_SK_REUSEPORT),
8824 SEC_DEF("kprobe/", KPROBE,
8825 .attach_fn = attach_kprobe),
8826 BPF_PROG_SEC("uprobe/", BPF_PROG_TYPE_KPROBE),
8827 SEC_DEF("kretprobe/", KPROBE,
8828 .attach_fn = attach_kprobe),
8829 BPF_PROG_SEC("uretprobe/", BPF_PROG_TYPE_KPROBE),
8830 BPF_PROG_SEC("classifier", BPF_PROG_TYPE_SCHED_CLS),
8831 BPF_PROG_SEC("action", BPF_PROG_TYPE_SCHED_ACT),
8832 SEC_DEF("tracepoint/", TRACEPOINT,
8833 .attach_fn = attach_tp),
8834 SEC_DEF("tp/", TRACEPOINT,
8835 .attach_fn = attach_tp),
8836 SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT,
8837 .attach_fn = attach_raw_tp),
8838 SEC_DEF("raw_tp/", RAW_TRACEPOINT,
8839 .attach_fn = attach_raw_tp),
8840 SEC_DEF("tp_btf/", TRACING,
8841 .expected_attach_type = BPF_TRACE_RAW_TP,
8842 .is_attach_btf = true,
8843 .attach_fn = attach_trace),
8844 SEC_DEF("fentry/", TRACING,
8845 .expected_attach_type = BPF_TRACE_FENTRY,
8846 .is_attach_btf = true,
8847 .attach_fn = attach_trace),
8848 SEC_DEF("fmod_ret/", TRACING,
8849 .expected_attach_type = BPF_MODIFY_RETURN,
8850 .is_attach_btf = true,
8851 .attach_fn = attach_trace),
8852 SEC_DEF("fexit/", TRACING,
8853 .expected_attach_type = BPF_TRACE_FEXIT,
8854 .is_attach_btf = true,
8855 .attach_fn = attach_trace),
8856 SEC_DEF("fentry.s/", TRACING,
8857 .expected_attach_type = BPF_TRACE_FENTRY,
8858 .is_attach_btf = true,
8859 .is_sleepable = true,
8860 .attach_fn = attach_trace),
8861 SEC_DEF("fmod_ret.s/", TRACING,
8862 .expected_attach_type = BPF_MODIFY_RETURN,
8863 .is_attach_btf = true,
8864 .is_sleepable = true,
8865 .attach_fn = attach_trace),
8866 SEC_DEF("fexit.s/", TRACING,
8867 .expected_attach_type = BPF_TRACE_FEXIT,
8868 .is_attach_btf = true,
8869 .is_sleepable = true,
8870 .attach_fn = attach_trace),
8871 SEC_DEF("freplace/", EXT,
8872 .is_attach_btf = true,
8873 .attach_fn = attach_trace),
8874 SEC_DEF("lsm/", LSM,
8875 .is_attach_btf = true,
8876 .expected_attach_type = BPF_LSM_MAC,
8877 .attach_fn = attach_lsm),
8878 SEC_DEF("lsm.s/", LSM,
8879 .is_attach_btf = true,
8880 .is_sleepable = true,
8881 .expected_attach_type = BPF_LSM_MAC,
8882 .attach_fn = attach_lsm),
8883 SEC_DEF("iter/", TRACING,
8884 .expected_attach_type = BPF_TRACE_ITER,
8885 .is_attach_btf = true,
8886 .attach_fn = attach_iter),
8887 BPF_EAPROG_SEC("xdp_devmap/", BPF_PROG_TYPE_XDP,
8888 BPF_XDP_DEVMAP),
8889 BPF_EAPROG_SEC("xdp_cpumap/", BPF_PROG_TYPE_XDP,
8890 BPF_XDP_CPUMAP),
8891 BPF_APROG_SEC("xdp", BPF_PROG_TYPE_XDP,
8892 BPF_XDP),
8893 BPF_PROG_SEC("perf_event", BPF_PROG_TYPE_PERF_EVENT),
8894 BPF_PROG_SEC("lwt_in", BPF_PROG_TYPE_LWT_IN),
8895 BPF_PROG_SEC("lwt_out", BPF_PROG_TYPE_LWT_OUT),
8896 BPF_PROG_SEC("lwt_xmit", BPF_PROG_TYPE_LWT_XMIT),
8897 BPF_PROG_SEC("lwt_seg6local", BPF_PROG_TYPE_LWT_SEG6LOCAL),
8898 BPF_APROG_SEC("cgroup_skb/ingress", BPF_PROG_TYPE_CGROUP_SKB,
8899 BPF_CGROUP_INET_INGRESS),
8900 BPF_APROG_SEC("cgroup_skb/egress", BPF_PROG_TYPE_CGROUP_SKB,
8901 BPF_CGROUP_INET_EGRESS),
8902 BPF_APROG_COMPAT("cgroup/skb", BPF_PROG_TYPE_CGROUP_SKB),
8903 BPF_EAPROG_SEC("cgroup/sock_create", BPF_PROG_TYPE_CGROUP_SOCK,
8904 BPF_CGROUP_INET_SOCK_CREATE),
8905 BPF_EAPROG_SEC("cgroup/sock_release", BPF_PROG_TYPE_CGROUP_SOCK,
8906 BPF_CGROUP_INET_SOCK_RELEASE),
8907 BPF_APROG_SEC("cgroup/sock", BPF_PROG_TYPE_CGROUP_SOCK,
8908 BPF_CGROUP_INET_SOCK_CREATE),
8909 BPF_EAPROG_SEC("cgroup/post_bind4", BPF_PROG_TYPE_CGROUP_SOCK,
8910 BPF_CGROUP_INET4_POST_BIND),
8911 BPF_EAPROG_SEC("cgroup/post_bind6", BPF_PROG_TYPE_CGROUP_SOCK,
8912 BPF_CGROUP_INET6_POST_BIND),
8913 BPF_APROG_SEC("cgroup/dev", BPF_PROG_TYPE_CGROUP_DEVICE,
8914 BPF_CGROUP_DEVICE),
8915 BPF_APROG_SEC("sockops", BPF_PROG_TYPE_SOCK_OPS,
8916 BPF_CGROUP_SOCK_OPS),
8917 BPF_APROG_SEC("sk_skb/stream_parser", BPF_PROG_TYPE_SK_SKB,
8918 BPF_SK_SKB_STREAM_PARSER),
8919 BPF_APROG_SEC("sk_skb/stream_verdict", BPF_PROG_TYPE_SK_SKB,
8920 BPF_SK_SKB_STREAM_VERDICT),
8921 BPF_APROG_COMPAT("sk_skb", BPF_PROG_TYPE_SK_SKB),
8922 BPF_APROG_SEC("sk_msg", BPF_PROG_TYPE_SK_MSG,
8923 BPF_SK_MSG_VERDICT),
8924 BPF_APROG_SEC("lirc_mode2", BPF_PROG_TYPE_LIRC_MODE2,
8925 BPF_LIRC_MODE2),
8926 BPF_APROG_SEC("flow_dissector", BPF_PROG_TYPE_FLOW_DISSECTOR,
8927 BPF_FLOW_DISSECTOR),
8928 BPF_EAPROG_SEC("cgroup/bind4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8929 BPF_CGROUP_INET4_BIND),
8930 BPF_EAPROG_SEC("cgroup/bind6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8931 BPF_CGROUP_INET6_BIND),
8932 BPF_EAPROG_SEC("cgroup/connect4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8933 BPF_CGROUP_INET4_CONNECT),
8934 BPF_EAPROG_SEC("cgroup/connect6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8935 BPF_CGROUP_INET6_CONNECT),
8936 BPF_EAPROG_SEC("cgroup/sendmsg4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8937 BPF_CGROUP_UDP4_SENDMSG),
8938 BPF_EAPROG_SEC("cgroup/sendmsg6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8939 BPF_CGROUP_UDP6_SENDMSG),
8940 BPF_EAPROG_SEC("cgroup/recvmsg4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8941 BPF_CGROUP_UDP4_RECVMSG),
8942 BPF_EAPROG_SEC("cgroup/recvmsg6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8943 BPF_CGROUP_UDP6_RECVMSG),
8944 BPF_EAPROG_SEC("cgroup/getpeername4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8945 BPF_CGROUP_INET4_GETPEERNAME),
8946 BPF_EAPROG_SEC("cgroup/getpeername6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8947 BPF_CGROUP_INET6_GETPEERNAME),
8948 BPF_EAPROG_SEC("cgroup/getsockname4", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8949 BPF_CGROUP_INET4_GETSOCKNAME),
8950 BPF_EAPROG_SEC("cgroup/getsockname6", BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
8951 BPF_CGROUP_INET6_GETSOCKNAME),
8952 BPF_EAPROG_SEC("cgroup/sysctl", BPF_PROG_TYPE_CGROUP_SYSCTL,
8953 BPF_CGROUP_SYSCTL),
8954 BPF_EAPROG_SEC("cgroup/getsockopt", BPF_PROG_TYPE_CGROUP_SOCKOPT,
8955 BPF_CGROUP_GETSOCKOPT),
8956 BPF_EAPROG_SEC("cgroup/setsockopt", BPF_PROG_TYPE_CGROUP_SOCKOPT,
8957 BPF_CGROUP_SETSOCKOPT),
8958 BPF_PROG_SEC("struct_ops", BPF_PROG_TYPE_STRUCT_OPS),
8959 BPF_EAPROG_SEC("sk_lookup/", BPF_PROG_TYPE_SK_LOOKUP,
8960 BPF_SK_LOOKUP),
8961 };
8962
8963 #undef BPF_PROG_SEC_IMPL
8964 #undef BPF_PROG_SEC
8965 #undef BPF_APROG_SEC
8966 #undef BPF_EAPROG_SEC
8967 #undef BPF_APROG_COMPAT
8968 #undef SEC_DEF
8969
8970 #define MAX_TYPE_NAME_SIZE 32
8971
find_sec_def(const char * sec_name)8972 static const struct bpf_sec_def *find_sec_def(const char *sec_name)
8973 {
8974 int i, n = ARRAY_SIZE(section_defs);
8975
8976 for (i = 0; i < n; i++) {
8977 if (strncmp(sec_name,
8978 section_defs[i].sec, section_defs[i].len))
8979 continue;
8980 return §ion_defs[i];
8981 }
8982 return NULL;
8983 }
8984
libbpf_get_type_names(bool attach_type)8985 static char *libbpf_get_type_names(bool attach_type)
8986 {
8987 int i, len = ARRAY_SIZE(section_defs) * MAX_TYPE_NAME_SIZE;
8988 char *buf;
8989
8990 buf = malloc(len);
8991 if (!buf)
8992 return NULL;
8993
8994 buf[0] = '\0';
8995 /* Forge string buf with all available names */
8996 for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
8997 if (attach_type && !section_defs[i].is_attachable)
8998 continue;
8999
9000 if (strlen(buf) + strlen(section_defs[i].sec) + 2 > len) {
9001 free(buf);
9002 return NULL;
9003 }
9004 strcat(buf, " ");
9005 strcat(buf, section_defs[i].sec);
9006 }
9007
9008 return buf;
9009 }
9010
libbpf_prog_type_by_name(const char * name,enum bpf_prog_type * prog_type,enum bpf_attach_type * expected_attach_type)9011 int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
9012 enum bpf_attach_type *expected_attach_type)
9013 {
9014 const struct bpf_sec_def *sec_def;
9015 char *type_names;
9016
9017 if (!name)
9018 return -EINVAL;
9019
9020 sec_def = find_sec_def(name);
9021 if (sec_def) {
9022 *prog_type = sec_def->prog_type;
9023 *expected_attach_type = sec_def->expected_attach_type;
9024 return 0;
9025 }
9026
9027 pr_debug("failed to guess program type from ELF section '%s'\n", name);
9028 type_names = libbpf_get_type_names(false);
9029 if (type_names != NULL) {
9030 pr_debug("supported section(type) names are:%s\n", type_names);
9031 free(type_names);
9032 }
9033
9034 return -ESRCH;
9035 }
9036
find_struct_ops_map_by_offset(struct bpf_object * obj,size_t offset)9037 static struct bpf_map *find_struct_ops_map_by_offset(struct bpf_object *obj,
9038 size_t offset)
9039 {
9040 struct bpf_map *map;
9041 size_t i;
9042
9043 for (i = 0; i < obj->nr_maps; i++) {
9044 map = &obj->maps[i];
9045 if (!bpf_map__is_struct_ops(map))
9046 continue;
9047 if (map->sec_offset <= offset &&
9048 offset - map->sec_offset < map->def.value_size)
9049 return map;
9050 }
9051
9052 return NULL;
9053 }
9054
9055 /* Collect the reloc from ELF and populate the st_ops->progs[] */
bpf_object__collect_st_ops_relos(struct bpf_object * obj,GElf_Shdr * shdr,Elf_Data * data)9056 static int bpf_object__collect_st_ops_relos(struct bpf_object *obj,
9057 GElf_Shdr *shdr, Elf_Data *data)
9058 {
9059 const struct btf_member *member;
9060 struct bpf_struct_ops *st_ops;
9061 struct bpf_program *prog;
9062 unsigned int shdr_idx;
9063 const struct btf *btf;
9064 struct bpf_map *map;
9065 Elf_Data *symbols;
9066 unsigned int moff, insn_idx;
9067 const char *name;
9068 __u32 member_idx;
9069 GElf_Sym sym;
9070 GElf_Rel rel;
9071 int i, nrels;
9072
9073 symbols = obj->efile.symbols;
9074 btf = obj->btf;
9075 nrels = shdr->sh_size / shdr->sh_entsize;
9076 for (i = 0; i < nrels; i++) {
9077 if (!gelf_getrel(data, i, &rel)) {
9078 pr_warn("struct_ops reloc: failed to get %d reloc\n", i);
9079 return -LIBBPF_ERRNO__FORMAT;
9080 }
9081
9082 if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
9083 pr_warn("struct_ops reloc: symbol %zx not found\n",
9084 (size_t)GELF_R_SYM(rel.r_info));
9085 return -LIBBPF_ERRNO__FORMAT;
9086 }
9087
9088 name = elf_sym_str(obj, sym.st_name) ?: "<?>";
9089 map = find_struct_ops_map_by_offset(obj, rel.r_offset);
9090 if (!map) {
9091 pr_warn("struct_ops reloc: cannot find map at rel.r_offset %zu\n",
9092 (size_t)rel.r_offset);
9093 return -EINVAL;
9094 }
9095
9096 moff = rel.r_offset - map->sec_offset;
9097 shdr_idx = sym.st_shndx;
9098 st_ops = map->st_ops;
9099 pr_debug("struct_ops reloc %s: for %lld value %lld shdr_idx %u rel.r_offset %zu map->sec_offset %zu name %d (\'%s\')\n",
9100 map->name,
9101 (long long)(rel.r_info >> 32),
9102 (long long)sym.st_value,
9103 shdr_idx, (size_t)rel.r_offset,
9104 map->sec_offset, sym.st_name, name);
9105
9106 if (shdr_idx >= SHN_LORESERVE) {
9107 pr_warn("struct_ops reloc %s: rel.r_offset %zu shdr_idx %u unsupported non-static function\n",
9108 map->name, (size_t)rel.r_offset, shdr_idx);
9109 return -LIBBPF_ERRNO__RELOC;
9110 }
9111 if (sym.st_value % BPF_INSN_SZ) {
9112 pr_warn("struct_ops reloc %s: invalid target program offset %llu\n",
9113 map->name, (unsigned long long)sym.st_value);
9114 return -LIBBPF_ERRNO__FORMAT;
9115 }
9116 insn_idx = sym.st_value / BPF_INSN_SZ;
9117
9118 member = find_member_by_offset(st_ops->type, moff * 8);
9119 if (!member) {
9120 pr_warn("struct_ops reloc %s: cannot find member at moff %u\n",
9121 map->name, moff);
9122 return -EINVAL;
9123 }
9124 member_idx = member - btf_members(st_ops->type);
9125 name = btf__name_by_offset(btf, member->name_off);
9126
9127 if (!resolve_func_ptr(btf, member->type, NULL)) {
9128 pr_warn("struct_ops reloc %s: cannot relocate non func ptr %s\n",
9129 map->name, name);
9130 return -EINVAL;
9131 }
9132
9133 prog = find_prog_by_sec_insn(obj, shdr_idx, insn_idx);
9134 if (!prog) {
9135 pr_warn("struct_ops reloc %s: cannot find prog at shdr_idx %u to relocate func ptr %s\n",
9136 map->name, shdr_idx, name);
9137 return -EINVAL;
9138 }
9139
9140 if (prog->type == BPF_PROG_TYPE_UNSPEC) {
9141 const struct bpf_sec_def *sec_def;
9142
9143 sec_def = find_sec_def(prog->sec_name);
9144 if (sec_def &&
9145 sec_def->prog_type != BPF_PROG_TYPE_STRUCT_OPS) {
9146 /* for pr_warn */
9147 prog->type = sec_def->prog_type;
9148 goto invalid_prog;
9149 }
9150
9151 prog->type = BPF_PROG_TYPE_STRUCT_OPS;
9152 prog->attach_btf_id = st_ops->type_id;
9153 prog->expected_attach_type = member_idx;
9154 } else if (prog->type != BPF_PROG_TYPE_STRUCT_OPS ||
9155 prog->attach_btf_id != st_ops->type_id ||
9156 prog->expected_attach_type != member_idx) {
9157 goto invalid_prog;
9158 }
9159 st_ops->progs[member_idx] = prog;
9160 }
9161
9162 return 0;
9163
9164 invalid_prog:
9165 pr_warn("struct_ops reloc %s: cannot use prog %s in sec %s with type %u attach_btf_id %u expected_attach_type %u for func ptr %s\n",
9166 map->name, prog->name, prog->sec_name, prog->type,
9167 prog->attach_btf_id, prog->expected_attach_type, name);
9168 return -EINVAL;
9169 }
9170
9171 #define BTF_TRACE_PREFIX "btf_trace_"
9172 #define BTF_LSM_PREFIX "bpf_lsm_"
9173 #define BTF_ITER_PREFIX "bpf_iter_"
9174 #define BTF_MAX_NAME_SIZE 128
9175
find_btf_by_prefix_kind(const struct btf * btf,const char * prefix,const char * name,__u32 kind)9176 static int find_btf_by_prefix_kind(const struct btf *btf, const char *prefix,
9177 const char *name, __u32 kind)
9178 {
9179 char btf_type_name[BTF_MAX_NAME_SIZE];
9180 int ret;
9181
9182 ret = snprintf(btf_type_name, sizeof(btf_type_name),
9183 "%s%s", prefix, name);
9184 /* snprintf returns the number of characters written excluding the
9185 * the terminating null. So, if >= BTF_MAX_NAME_SIZE are written, it
9186 * indicates truncation.
9187 */
9188 if (ret < 0 || ret >= sizeof(btf_type_name))
9189 return -ENAMETOOLONG;
9190 return btf__find_by_name_kind(btf, btf_type_name, kind);
9191 }
9192
find_attach_btf_id(struct btf * btf,const char * name,enum bpf_attach_type attach_type)9193 static inline int find_attach_btf_id(struct btf *btf, const char *name,
9194 enum bpf_attach_type attach_type)
9195 {
9196 int err;
9197
9198 if (attach_type == BPF_TRACE_RAW_TP)
9199 err = find_btf_by_prefix_kind(btf, BTF_TRACE_PREFIX, name,
9200 BTF_KIND_TYPEDEF);
9201 else if (attach_type == BPF_LSM_MAC)
9202 err = find_btf_by_prefix_kind(btf, BTF_LSM_PREFIX, name,
9203 BTF_KIND_FUNC);
9204 else if (attach_type == BPF_TRACE_ITER)
9205 err = find_btf_by_prefix_kind(btf, BTF_ITER_PREFIX, name,
9206 BTF_KIND_FUNC);
9207 else
9208 err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
9209
9210 return err;
9211 }
9212
libbpf_find_vmlinux_btf_id(const char * name,enum bpf_attach_type attach_type)9213 int libbpf_find_vmlinux_btf_id(const char *name,
9214 enum bpf_attach_type attach_type)
9215 {
9216 struct btf *btf;
9217 int err;
9218
9219 btf = libbpf_find_kernel_btf();
9220 if (IS_ERR(btf)) {
9221 pr_warn("vmlinux BTF is not found\n");
9222 return -EINVAL;
9223 }
9224
9225 err = find_attach_btf_id(btf, name, attach_type);
9226 if (err <= 0)
9227 pr_warn("%s is not found in vmlinux BTF\n", name);
9228
9229 btf__free(btf);
9230 return err;
9231 }
9232
libbpf_find_prog_btf_id(const char * name,__u32 attach_prog_fd)9233 static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
9234 {
9235 struct bpf_prog_info_linear *info_linear;
9236 struct bpf_prog_info *info;
9237 struct btf *btf = NULL;
9238 int err = -EINVAL;
9239
9240 info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
9241 if (IS_ERR_OR_NULL(info_linear)) {
9242 pr_warn("failed get_prog_info_linear for FD %d\n",
9243 attach_prog_fd);
9244 return -EINVAL;
9245 }
9246 info = &info_linear->info;
9247 if (!info->btf_id) {
9248 pr_warn("The target program doesn't have BTF\n");
9249 goto out;
9250 }
9251 if (btf__get_from_id(info->btf_id, &btf)) {
9252 pr_warn("Failed to get BTF of the program\n");
9253 goto out;
9254 }
9255 err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
9256 btf__free(btf);
9257 if (err <= 0) {
9258 pr_warn("%s is not found in prog's BTF\n", name);
9259 goto out;
9260 }
9261 out:
9262 free(info_linear);
9263 return err;
9264 }
9265
find_kernel_btf_id(struct bpf_object * obj,const char * attach_name,enum bpf_attach_type attach_type,int * btf_obj_fd,int * btf_type_id)9266 static int find_kernel_btf_id(struct bpf_object *obj, const char *attach_name,
9267 enum bpf_attach_type attach_type,
9268 int *btf_obj_fd, int *btf_type_id)
9269 {
9270 int ret, i;
9271
9272 ret = find_attach_btf_id(obj->btf_vmlinux, attach_name, attach_type);
9273 if (ret > 0) {
9274 *btf_obj_fd = 0; /* vmlinux BTF */
9275 *btf_type_id = ret;
9276 return 0;
9277 }
9278 if (ret != -ENOENT)
9279 return ret;
9280
9281 ret = load_module_btfs(obj);
9282 if (ret)
9283 return ret;
9284
9285 for (i = 0; i < obj->btf_module_cnt; i++) {
9286 const struct module_btf *mod = &obj->btf_modules[i];
9287
9288 ret = find_attach_btf_id(mod->btf, attach_name, attach_type);
9289 if (ret > 0) {
9290 *btf_obj_fd = mod->fd;
9291 *btf_type_id = ret;
9292 return 0;
9293 }
9294 if (ret == -ENOENT)
9295 continue;
9296
9297 return ret;
9298 }
9299
9300 return -ESRCH;
9301 }
9302
libbpf_find_attach_btf_id(struct bpf_program * prog,int * btf_obj_fd,int * btf_type_id)9303 static int libbpf_find_attach_btf_id(struct bpf_program *prog, int *btf_obj_fd, int *btf_type_id)
9304 {
9305 enum bpf_attach_type attach_type = prog->expected_attach_type;
9306 __u32 attach_prog_fd = prog->attach_prog_fd;
9307 const char *name = prog->sec_name, *attach_name;
9308 const struct bpf_sec_def *sec = NULL;
9309 int i, err;
9310
9311 if (!name)
9312 return -EINVAL;
9313
9314 for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
9315 if (!section_defs[i].is_attach_btf)
9316 continue;
9317 if (strncmp(name, section_defs[i].sec, section_defs[i].len))
9318 continue;
9319
9320 sec = §ion_defs[i];
9321 break;
9322 }
9323
9324 if (!sec) {
9325 pr_warn("failed to identify BTF ID based on ELF section name '%s'\n", name);
9326 return -ESRCH;
9327 }
9328 attach_name = name + sec->len;
9329
9330 /* BPF program's BTF ID */
9331 if (attach_prog_fd) {
9332 err = libbpf_find_prog_btf_id(attach_name, attach_prog_fd);
9333 if (err < 0) {
9334 pr_warn("failed to find BPF program (FD %d) BTF ID for '%s': %d\n",
9335 attach_prog_fd, attach_name, err);
9336 return err;
9337 }
9338 *btf_obj_fd = 0;
9339 *btf_type_id = err;
9340 return 0;
9341 }
9342
9343 /* kernel/module BTF ID */
9344 err = find_kernel_btf_id(prog->obj, attach_name, attach_type, btf_obj_fd, btf_type_id);
9345 if (err) {
9346 pr_warn("failed to find kernel BTF type ID of '%s': %d\n", attach_name, err);
9347 return err;
9348 }
9349 return 0;
9350 }
9351
libbpf_attach_type_by_name(const char * name,enum bpf_attach_type * attach_type)9352 int libbpf_attach_type_by_name(const char *name,
9353 enum bpf_attach_type *attach_type)
9354 {
9355 char *type_names;
9356 int i;
9357
9358 if (!name)
9359 return -EINVAL;
9360
9361 for (i = 0; i < ARRAY_SIZE(section_defs); i++) {
9362 if (strncmp(name, section_defs[i].sec, section_defs[i].len))
9363 continue;
9364 if (!section_defs[i].is_attachable)
9365 return -EINVAL;
9366 *attach_type = section_defs[i].expected_attach_type;
9367 return 0;
9368 }
9369 pr_debug("failed to guess attach type based on ELF section name '%s'\n", name);
9370 type_names = libbpf_get_type_names(true);
9371 if (type_names != NULL) {
9372 pr_debug("attachable section(type) names are:%s\n", type_names);
9373 free(type_names);
9374 }
9375
9376 return -EINVAL;
9377 }
9378
bpf_map__fd(const struct bpf_map * map)9379 int bpf_map__fd(const struct bpf_map *map)
9380 {
9381 return map ? map->fd : -EINVAL;
9382 }
9383
bpf_map__def(const struct bpf_map * map)9384 const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
9385 {
9386 return map ? &map->def : ERR_PTR(-EINVAL);
9387 }
9388
bpf_map__name(const struct bpf_map * map)9389 const char *bpf_map__name(const struct bpf_map *map)
9390 {
9391 return map ? map->name : NULL;
9392 }
9393
bpf_map__type(const struct bpf_map * map)9394 enum bpf_map_type bpf_map__type(const struct bpf_map *map)
9395 {
9396 return map->def.type;
9397 }
9398
bpf_map__set_type(struct bpf_map * map,enum bpf_map_type type)9399 int bpf_map__set_type(struct bpf_map *map, enum bpf_map_type type)
9400 {
9401 if (map->fd >= 0)
9402 return -EBUSY;
9403 map->def.type = type;
9404 return 0;
9405 }
9406
bpf_map__map_flags(const struct bpf_map * map)9407 __u32 bpf_map__map_flags(const struct bpf_map *map)
9408 {
9409 return map->def.map_flags;
9410 }
9411
bpf_map__set_map_flags(struct bpf_map * map,__u32 flags)9412 int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
9413 {
9414 if (map->fd >= 0)
9415 return -EBUSY;
9416 map->def.map_flags = flags;
9417 return 0;
9418 }
9419
bpf_map__numa_node(const struct bpf_map * map)9420 __u32 bpf_map__numa_node(const struct bpf_map *map)
9421 {
9422 return map->numa_node;
9423 }
9424
bpf_map__set_numa_node(struct bpf_map * map,__u32 numa_node)9425 int bpf_map__set_numa_node(struct bpf_map *map, __u32 numa_node)
9426 {
9427 if (map->fd >= 0)
9428 return -EBUSY;
9429 map->numa_node = numa_node;
9430 return 0;
9431 }
9432
bpf_map__key_size(const struct bpf_map * map)9433 __u32 bpf_map__key_size(const struct bpf_map *map)
9434 {
9435 return map->def.key_size;
9436 }
9437
bpf_map__set_key_size(struct bpf_map * map,__u32 size)9438 int bpf_map__set_key_size(struct bpf_map *map, __u32 size)
9439 {
9440 if (map->fd >= 0)
9441 return -EBUSY;
9442 map->def.key_size = size;
9443 return 0;
9444 }
9445
bpf_map__value_size(const struct bpf_map * map)9446 __u32 bpf_map__value_size(const struct bpf_map *map)
9447 {
9448 return map->def.value_size;
9449 }
9450
bpf_map__set_value_size(struct bpf_map * map,__u32 size)9451 int bpf_map__set_value_size(struct bpf_map *map, __u32 size)
9452 {
9453 if (map->fd >= 0)
9454 return -EBUSY;
9455 map->def.value_size = size;
9456 return 0;
9457 }
9458
bpf_map__btf_key_type_id(const struct bpf_map * map)9459 __u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
9460 {
9461 return map ? map->btf_key_type_id : 0;
9462 }
9463
bpf_map__btf_value_type_id(const struct bpf_map * map)9464 __u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
9465 {
9466 return map ? map->btf_value_type_id : 0;
9467 }
9468
bpf_map__set_priv(struct bpf_map * map,void * priv,bpf_map_clear_priv_t clear_priv)9469 int bpf_map__set_priv(struct bpf_map *map, void *priv,
9470 bpf_map_clear_priv_t clear_priv)
9471 {
9472 if (!map)
9473 return -EINVAL;
9474
9475 if (map->priv) {
9476 if (map->clear_priv)
9477 map->clear_priv(map, map->priv);
9478 }
9479
9480 map->priv = priv;
9481 map->clear_priv = clear_priv;
9482 return 0;
9483 }
9484
bpf_map__priv(const struct bpf_map * map)9485 void *bpf_map__priv(const struct bpf_map *map)
9486 {
9487 return map ? map->priv : ERR_PTR(-EINVAL);
9488 }
9489
bpf_map__set_initial_value(struct bpf_map * map,const void * data,size_t size)9490 int bpf_map__set_initial_value(struct bpf_map *map,
9491 const void *data, size_t size)
9492 {
9493 if (!map->mmaped || map->libbpf_type == LIBBPF_MAP_KCONFIG ||
9494 size != map->def.value_size || map->fd >= 0)
9495 return -EINVAL;
9496
9497 memcpy(map->mmaped, data, size);
9498 return 0;
9499 }
9500
bpf_map__is_offload_neutral(const struct bpf_map * map)9501 bool bpf_map__is_offload_neutral(const struct bpf_map *map)
9502 {
9503 return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
9504 }
9505
bpf_map__is_internal(const struct bpf_map * map)9506 bool bpf_map__is_internal(const struct bpf_map *map)
9507 {
9508 return map->libbpf_type != LIBBPF_MAP_UNSPEC;
9509 }
9510
bpf_map__ifindex(const struct bpf_map * map)9511 __u32 bpf_map__ifindex(const struct bpf_map *map)
9512 {
9513 return map->map_ifindex;
9514 }
9515
bpf_map__set_ifindex(struct bpf_map * map,__u32 ifindex)9516 int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
9517 {
9518 if (map->fd >= 0)
9519 return -EBUSY;
9520 map->map_ifindex = ifindex;
9521 return 0;
9522 }
9523
bpf_map__set_inner_map_fd(struct bpf_map * map,int fd)9524 int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
9525 {
9526 if (!bpf_map_type__is_map_in_map(map->def.type)) {
9527 pr_warn("error: unsupported map type\n");
9528 return -EINVAL;
9529 }
9530 if (map->inner_map_fd != -1) {
9531 pr_warn("error: inner_map_fd already specified\n");
9532 return -EINVAL;
9533 }
9534 zfree(&map->inner_map);
9535 map->inner_map_fd = fd;
9536 return 0;
9537 }
9538
9539 static struct bpf_map *
__bpf_map__iter(const struct bpf_map * m,const struct bpf_object * obj,int i)9540 __bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
9541 {
9542 ssize_t idx;
9543 struct bpf_map *s, *e;
9544
9545 if (!obj || !obj->maps)
9546 return NULL;
9547
9548 s = obj->maps;
9549 e = obj->maps + obj->nr_maps;
9550
9551 if ((m < s) || (m >= e)) {
9552 pr_warn("error in %s: map handler doesn't belong to object\n",
9553 __func__);
9554 return NULL;
9555 }
9556
9557 idx = (m - obj->maps) + i;
9558 if (idx >= obj->nr_maps || idx < 0)
9559 return NULL;
9560 return &obj->maps[idx];
9561 }
9562
9563 struct bpf_map *
bpf_map__next(const struct bpf_map * prev,const struct bpf_object * obj)9564 bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj)
9565 {
9566 if (prev == NULL)
9567 return obj->maps;
9568
9569 return __bpf_map__iter(prev, obj, 1);
9570 }
9571
9572 struct bpf_map *
bpf_map__prev(const struct bpf_map * next,const struct bpf_object * obj)9573 bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj)
9574 {
9575 if (next == NULL) {
9576 if (!obj->nr_maps)
9577 return NULL;
9578 return obj->maps + obj->nr_maps - 1;
9579 }
9580
9581 return __bpf_map__iter(next, obj, -1);
9582 }
9583
9584 struct bpf_map *
bpf_object__find_map_by_name(const struct bpf_object * obj,const char * name)9585 bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
9586 {
9587 struct bpf_map *pos;
9588
9589 bpf_object__for_each_map(pos, obj) {
9590 if (pos->name && !strcmp(pos->name, name))
9591 return pos;
9592 }
9593 return NULL;
9594 }
9595
9596 int
bpf_object__find_map_fd_by_name(const struct bpf_object * obj,const char * name)9597 bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
9598 {
9599 return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
9600 }
9601
9602 struct bpf_map *
bpf_object__find_map_by_offset(struct bpf_object * obj,size_t offset)9603 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
9604 {
9605 return ERR_PTR(-ENOTSUP);
9606 }
9607
libbpf_get_error(const void * ptr)9608 long libbpf_get_error(const void *ptr)
9609 {
9610 return PTR_ERR_OR_ZERO(ptr);
9611 }
9612
bpf_prog_load(const char * file,enum bpf_prog_type type,struct bpf_object ** pobj,int * prog_fd)9613 int bpf_prog_load(const char *file, enum bpf_prog_type type,
9614 struct bpf_object **pobj, int *prog_fd)
9615 {
9616 struct bpf_prog_load_attr attr;
9617
9618 memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
9619 attr.file = file;
9620 attr.prog_type = type;
9621 attr.expected_attach_type = 0;
9622
9623 return bpf_prog_load_xattr(&attr, pobj, prog_fd);
9624 }
9625
bpf_prog_load_xattr(const struct bpf_prog_load_attr * attr,struct bpf_object ** pobj,int * prog_fd)9626 int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
9627 struct bpf_object **pobj, int *prog_fd)
9628 {
9629 struct bpf_object_open_attr open_attr = {};
9630 struct bpf_program *prog, *first_prog = NULL;
9631 struct bpf_object *obj;
9632 struct bpf_map *map;
9633 int err;
9634
9635 if (!attr)
9636 return -EINVAL;
9637 if (!attr->file)
9638 return -EINVAL;
9639
9640 open_attr.file = attr->file;
9641 open_attr.prog_type = attr->prog_type;
9642
9643 obj = bpf_object__open_xattr(&open_attr);
9644 if (IS_ERR_OR_NULL(obj))
9645 return -ENOENT;
9646
9647 bpf_object__for_each_program(prog, obj) {
9648 enum bpf_attach_type attach_type = attr->expected_attach_type;
9649 /*
9650 * to preserve backwards compatibility, bpf_prog_load treats
9651 * attr->prog_type, if specified, as an override to whatever
9652 * bpf_object__open guessed
9653 */
9654 if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) {
9655 bpf_program__set_type(prog, attr->prog_type);
9656 bpf_program__set_expected_attach_type(prog,
9657 attach_type);
9658 }
9659 if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) {
9660 /*
9661 * we haven't guessed from section name and user
9662 * didn't provide a fallback type, too bad...
9663 */
9664 bpf_object__close(obj);
9665 return -EINVAL;
9666 }
9667
9668 prog->prog_ifindex = attr->ifindex;
9669 prog->log_level = attr->log_level;
9670 prog->prog_flags |= attr->prog_flags;
9671 if (!first_prog)
9672 first_prog = prog;
9673 }
9674
9675 bpf_object__for_each_map(map, obj) {
9676 if (!bpf_map__is_offload_neutral(map))
9677 map->map_ifindex = attr->ifindex;
9678 }
9679
9680 if (!first_prog) {
9681 pr_warn("object file doesn't contain bpf program\n");
9682 bpf_object__close(obj);
9683 return -ENOENT;
9684 }
9685
9686 err = bpf_object__load(obj);
9687 if (err) {
9688 bpf_object__close(obj);
9689 return err;
9690 }
9691
9692 *pobj = obj;
9693 *prog_fd = bpf_program__fd(first_prog);
9694 return 0;
9695 }
9696
9697 struct bpf_link {
9698 int (*detach)(struct bpf_link *link);
9699 int (*destroy)(struct bpf_link *link);
9700 char *pin_path; /* NULL, if not pinned */
9701 int fd; /* hook FD, -1 if not applicable */
9702 bool disconnected;
9703 };
9704
9705 /* Replace link's underlying BPF program with the new one */
bpf_link__update_program(struct bpf_link * link,struct bpf_program * prog)9706 int bpf_link__update_program(struct bpf_link *link, struct bpf_program *prog)
9707 {
9708 return bpf_link_update(bpf_link__fd(link), bpf_program__fd(prog), NULL);
9709 }
9710
9711 /* Release "ownership" of underlying BPF resource (typically, BPF program
9712 * attached to some BPF hook, e.g., tracepoint, kprobe, etc). Disconnected
9713 * link, when destructed through bpf_link__destroy() call won't attempt to
9714 * detach/unregisted that BPF resource. This is useful in situations where,
9715 * say, attached BPF program has to outlive userspace program that attached it
9716 * in the system. Depending on type of BPF program, though, there might be
9717 * additional steps (like pinning BPF program in BPF FS) necessary to ensure
9718 * exit of userspace program doesn't trigger automatic detachment and clean up
9719 * inside the kernel.
9720 */
bpf_link__disconnect(struct bpf_link * link)9721 void bpf_link__disconnect(struct bpf_link *link)
9722 {
9723 link->disconnected = true;
9724 }
9725
bpf_link__destroy(struct bpf_link * link)9726 int bpf_link__destroy(struct bpf_link *link)
9727 {
9728 int err = 0;
9729
9730 if (IS_ERR_OR_NULL(link))
9731 return 0;
9732
9733 if (!link->disconnected && link->detach)
9734 err = link->detach(link);
9735 if (link->destroy)
9736 link->destroy(link);
9737 if (link->pin_path)
9738 free(link->pin_path);
9739 free(link);
9740
9741 return err;
9742 }
9743
bpf_link__fd(const struct bpf_link * link)9744 int bpf_link__fd(const struct bpf_link *link)
9745 {
9746 return link->fd;
9747 }
9748
bpf_link__pin_path(const struct bpf_link * link)9749 const char *bpf_link__pin_path(const struct bpf_link *link)
9750 {
9751 return link->pin_path;
9752 }
9753
bpf_link__detach_fd(struct bpf_link * link)9754 static int bpf_link__detach_fd(struct bpf_link *link)
9755 {
9756 return close(link->fd);
9757 }
9758
bpf_link__open(const char * path)9759 struct bpf_link *bpf_link__open(const char *path)
9760 {
9761 struct bpf_link *link;
9762 int fd;
9763
9764 fd = bpf_obj_get(path);
9765 if (fd < 0) {
9766 fd = -errno;
9767 pr_warn("failed to open link at %s: %d\n", path, fd);
9768 return ERR_PTR(fd);
9769 }
9770
9771 link = calloc(1, sizeof(*link));
9772 if (!link) {
9773 close(fd);
9774 return ERR_PTR(-ENOMEM);
9775 }
9776 link->detach = &bpf_link__detach_fd;
9777 link->fd = fd;
9778
9779 link->pin_path = strdup(path);
9780 if (!link->pin_path) {
9781 bpf_link__destroy(link);
9782 return ERR_PTR(-ENOMEM);
9783 }
9784
9785 return link;
9786 }
9787
bpf_link__detach(struct bpf_link * link)9788 int bpf_link__detach(struct bpf_link *link)
9789 {
9790 return bpf_link_detach(link->fd) ? -errno : 0;
9791 }
9792
bpf_link__pin(struct bpf_link * link,const char * path)9793 int bpf_link__pin(struct bpf_link *link, const char *path)
9794 {
9795 int err;
9796
9797 if (link->pin_path)
9798 return -EBUSY;
9799 err = make_parent_dir(path);
9800 if (err)
9801 return err;
9802 err = check_path(path);
9803 if (err)
9804 return err;
9805
9806 link->pin_path = strdup(path);
9807 if (!link->pin_path)
9808 return -ENOMEM;
9809
9810 if (bpf_obj_pin(link->fd, link->pin_path)) {
9811 err = -errno;
9812 zfree(&link->pin_path);
9813 return err;
9814 }
9815
9816 pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
9817 return 0;
9818 }
9819
bpf_link__unpin(struct bpf_link * link)9820 int bpf_link__unpin(struct bpf_link *link)
9821 {
9822 int err;
9823
9824 if (!link->pin_path)
9825 return -EINVAL;
9826
9827 err = unlink(link->pin_path);
9828 if (err != 0)
9829 return -errno;
9830
9831 pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
9832 zfree(&link->pin_path);
9833 return 0;
9834 }
9835
bpf_link__detach_perf_event(struct bpf_link * link)9836 static int bpf_link__detach_perf_event(struct bpf_link *link)
9837 {
9838 int err;
9839
9840 err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0);
9841 if (err)
9842 err = -errno;
9843
9844 close(link->fd);
9845 return err;
9846 }
9847
bpf_program__attach_perf_event(struct bpf_program * prog,int pfd)9848 struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
9849 int pfd)
9850 {
9851 char errmsg[STRERR_BUFSIZE];
9852 struct bpf_link *link;
9853 int prog_fd, err;
9854
9855 if (pfd < 0) {
9856 pr_warn("prog '%s': invalid perf event FD %d\n",
9857 prog->name, pfd);
9858 return ERR_PTR(-EINVAL);
9859 }
9860 prog_fd = bpf_program__fd(prog);
9861 if (prog_fd < 0) {
9862 pr_warn("prog '%s': can't attach BPF program w/o FD (did you load it?)\n",
9863 prog->name);
9864 return ERR_PTR(-EINVAL);
9865 }
9866
9867 link = calloc(1, sizeof(*link));
9868 if (!link)
9869 return ERR_PTR(-ENOMEM);
9870 link->detach = &bpf_link__detach_perf_event;
9871 link->fd = pfd;
9872
9873 if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
9874 err = -errno;
9875 free(link);
9876 pr_warn("prog '%s': failed to attach to pfd %d: %s\n",
9877 prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
9878 if (err == -EPROTO)
9879 pr_warn("prog '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n",
9880 prog->name, pfd);
9881 return ERR_PTR(err);
9882 }
9883 if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
9884 err = -errno;
9885 free(link);
9886 pr_warn("prog '%s': failed to enable pfd %d: %s\n",
9887 prog->name, pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
9888 return ERR_PTR(err);
9889 }
9890 return link;
9891 }
9892
9893 /*
9894 * this function is expected to parse integer in the range of [0, 2^31-1] from
9895 * given file using scanf format string fmt. If actual parsed value is
9896 * negative, the result might be indistinguishable from error
9897 */
parse_uint_from_file(const char * file,const char * fmt)9898 static int parse_uint_from_file(const char *file, const char *fmt)
9899 {
9900 char buf[STRERR_BUFSIZE];
9901 int err, ret;
9902 FILE *f;
9903
9904 f = fopen(file, "r");
9905 if (!f) {
9906 err = -errno;
9907 pr_debug("failed to open '%s': %s\n", file,
9908 libbpf_strerror_r(err, buf, sizeof(buf)));
9909 return err;
9910 }
9911 err = fscanf(f, fmt, &ret);
9912 if (err != 1) {
9913 err = err == EOF ? -EIO : -errno;
9914 pr_debug("failed to parse '%s': %s\n", file,
9915 libbpf_strerror_r(err, buf, sizeof(buf)));
9916 fclose(f);
9917 return err;
9918 }
9919 fclose(f);
9920 return ret;
9921 }
9922
determine_kprobe_perf_type(void)9923 static int determine_kprobe_perf_type(void)
9924 {
9925 const char *file = "/sys/bus/event_source/devices/kprobe/type";
9926
9927 return parse_uint_from_file(file, "%d\n");
9928 }
9929
determine_uprobe_perf_type(void)9930 static int determine_uprobe_perf_type(void)
9931 {
9932 const char *file = "/sys/bus/event_source/devices/uprobe/type";
9933
9934 return parse_uint_from_file(file, "%d\n");
9935 }
9936
determine_kprobe_retprobe_bit(void)9937 static int determine_kprobe_retprobe_bit(void)
9938 {
9939 const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
9940
9941 return parse_uint_from_file(file, "config:%d\n");
9942 }
9943
determine_uprobe_retprobe_bit(void)9944 static int determine_uprobe_retprobe_bit(void)
9945 {
9946 const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
9947
9948 return parse_uint_from_file(file, "config:%d\n");
9949 }
9950
perf_event_open_probe(bool uprobe,bool retprobe,const char * name,uint64_t offset,int pid)9951 static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
9952 uint64_t offset, int pid)
9953 {
9954 struct perf_event_attr attr = {};
9955 char errmsg[STRERR_BUFSIZE];
9956 int type, pfd, err;
9957
9958 type = uprobe ? determine_uprobe_perf_type()
9959 : determine_kprobe_perf_type();
9960 if (type < 0) {
9961 pr_warn("failed to determine %s perf type: %s\n",
9962 uprobe ? "uprobe" : "kprobe",
9963 libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
9964 return type;
9965 }
9966 if (retprobe) {
9967 int bit = uprobe ? determine_uprobe_retprobe_bit()
9968 : determine_kprobe_retprobe_bit();
9969
9970 if (bit < 0) {
9971 pr_warn("failed to determine %s retprobe bit: %s\n",
9972 uprobe ? "uprobe" : "kprobe",
9973 libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
9974 return bit;
9975 }
9976 attr.config |= 1 << bit;
9977 }
9978 attr.size = sizeof(attr);
9979 attr.type = type;
9980 attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
9981 attr.config2 = offset; /* kprobe_addr or probe_offset */
9982
9983 /* pid filter is meaningful only for uprobes */
9984 pfd = syscall(__NR_perf_event_open, &attr,
9985 pid < 0 ? -1 : pid /* pid */,
9986 pid == -1 ? 0 : -1 /* cpu */,
9987 -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
9988 if (pfd < 0) {
9989 err = -errno;
9990 pr_warn("%s perf_event_open() failed: %s\n",
9991 uprobe ? "uprobe" : "kprobe",
9992 libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
9993 return err;
9994 }
9995 return pfd;
9996 }
9997
bpf_program__attach_kprobe(struct bpf_program * prog,bool retprobe,const char * func_name)9998 struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
9999 bool retprobe,
10000 const char *func_name)
10001 {
10002 char errmsg[STRERR_BUFSIZE];
10003 struct bpf_link *link;
10004 int pfd, err;
10005
10006 pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
10007 0 /* offset */, -1 /* pid */);
10008 if (pfd < 0) {
10009 pr_warn("prog '%s': failed to create %s '%s' perf event: %s\n",
10010 prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
10011 libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
10012 return ERR_PTR(pfd);
10013 }
10014 link = bpf_program__attach_perf_event(prog, pfd);
10015 if (IS_ERR(link)) {
10016 close(pfd);
10017 err = PTR_ERR(link);
10018 pr_warn("prog '%s': failed to attach to %s '%s': %s\n",
10019 prog->name, retprobe ? "kretprobe" : "kprobe", func_name,
10020 libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
10021 return link;
10022 }
10023 return link;
10024 }
10025
attach_kprobe(const struct bpf_sec_def * sec,struct bpf_program * prog)10026 static struct bpf_link *attach_kprobe(const struct bpf_sec_def *sec,
10027 struct bpf_program *prog)
10028 {
10029 const char *func_name;
10030 bool retprobe;
10031
10032 func_name = prog->sec_name + sec->len;
10033 retprobe = strcmp(sec->sec, "kretprobe/") == 0;
10034
10035 return bpf_program__attach_kprobe(prog, retprobe, func_name);
10036 }
10037
bpf_program__attach_uprobe(struct bpf_program * prog,bool retprobe,pid_t pid,const char * binary_path,size_t func_offset)10038 struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
10039 bool retprobe, pid_t pid,
10040 const char *binary_path,
10041 size_t func_offset)
10042 {
10043 char errmsg[STRERR_BUFSIZE];
10044 struct bpf_link *link;
10045 int pfd, err;
10046
10047 pfd = perf_event_open_probe(true /* uprobe */, retprobe,
10048 binary_path, func_offset, pid);
10049 if (pfd < 0) {
10050 pr_warn("prog '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
10051 prog->name, retprobe ? "uretprobe" : "uprobe",
10052 binary_path, func_offset,
10053 libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
10054 return ERR_PTR(pfd);
10055 }
10056 link = bpf_program__attach_perf_event(prog, pfd);
10057 if (IS_ERR(link)) {
10058 close(pfd);
10059 err = PTR_ERR(link);
10060 pr_warn("prog '%s': failed to attach to %s '%s:0x%zx': %s\n",
10061 prog->name, retprobe ? "uretprobe" : "uprobe",
10062 binary_path, func_offset,
10063 libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
10064 return link;
10065 }
10066 return link;
10067 }
10068
determine_tracepoint_id(const char * tp_category,const char * tp_name)10069 static int determine_tracepoint_id(const char *tp_category,
10070 const char *tp_name)
10071 {
10072 char file[PATH_MAX];
10073 int ret;
10074
10075 ret = snprintf(file, sizeof(file),
10076 "/sys/kernel/debug/tracing/events/%s/%s/id",
10077 tp_category, tp_name);
10078 if (ret < 0)
10079 return -errno;
10080 if (ret >= sizeof(file)) {
10081 pr_debug("tracepoint %s/%s path is too long\n",
10082 tp_category, tp_name);
10083 return -E2BIG;
10084 }
10085 return parse_uint_from_file(file, "%d\n");
10086 }
10087
perf_event_open_tracepoint(const char * tp_category,const char * tp_name)10088 static int perf_event_open_tracepoint(const char *tp_category,
10089 const char *tp_name)
10090 {
10091 struct perf_event_attr attr = {};
10092 char errmsg[STRERR_BUFSIZE];
10093 int tp_id, pfd, err;
10094
10095 tp_id = determine_tracepoint_id(tp_category, tp_name);
10096 if (tp_id < 0) {
10097 pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
10098 tp_category, tp_name,
10099 libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
10100 return tp_id;
10101 }
10102
10103 attr.type = PERF_TYPE_TRACEPOINT;
10104 attr.size = sizeof(attr);
10105 attr.config = tp_id;
10106
10107 pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
10108 -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
10109 if (pfd < 0) {
10110 err = -errno;
10111 pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
10112 tp_category, tp_name,
10113 libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
10114 return err;
10115 }
10116 return pfd;
10117 }
10118
bpf_program__attach_tracepoint(struct bpf_program * prog,const char * tp_category,const char * tp_name)10119 struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
10120 const char *tp_category,
10121 const char *tp_name)
10122 {
10123 char errmsg[STRERR_BUFSIZE];
10124 struct bpf_link *link;
10125 int pfd, err;
10126
10127 pfd = perf_event_open_tracepoint(tp_category, tp_name);
10128 if (pfd < 0) {
10129 pr_warn("prog '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
10130 prog->name, tp_category, tp_name,
10131 libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
10132 return ERR_PTR(pfd);
10133 }
10134 link = bpf_program__attach_perf_event(prog, pfd);
10135 if (IS_ERR(link)) {
10136 close(pfd);
10137 err = PTR_ERR(link);
10138 pr_warn("prog '%s': failed to attach to tracepoint '%s/%s': %s\n",
10139 prog->name, tp_category, tp_name,
10140 libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
10141 return link;
10142 }
10143 return link;
10144 }
10145
attach_tp(const struct bpf_sec_def * sec,struct bpf_program * prog)10146 static struct bpf_link *attach_tp(const struct bpf_sec_def *sec,
10147 struct bpf_program *prog)
10148 {
10149 char *sec_name, *tp_cat, *tp_name;
10150 struct bpf_link *link;
10151
10152 sec_name = strdup(prog->sec_name);
10153 if (!sec_name)
10154 return ERR_PTR(-ENOMEM);
10155
10156 /* extract "tp/<category>/<name>" */
10157 tp_cat = sec_name + sec->len;
10158 tp_name = strchr(tp_cat, '/');
10159 if (!tp_name) {
10160 link = ERR_PTR(-EINVAL);
10161 goto out;
10162 }
10163 *tp_name = '\0';
10164 tp_name++;
10165
10166 link = bpf_program__attach_tracepoint(prog, tp_cat, tp_name);
10167 out:
10168 free(sec_name);
10169 return link;
10170 }
10171
bpf_program__attach_raw_tracepoint(struct bpf_program * prog,const char * tp_name)10172 struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
10173 const char *tp_name)
10174 {
10175 char errmsg[STRERR_BUFSIZE];
10176 struct bpf_link *link;
10177 int prog_fd, pfd;
10178
10179 prog_fd = bpf_program__fd(prog);
10180 if (prog_fd < 0) {
10181 pr_warn("prog '%s': can't attach before loaded\n", prog->name);
10182 return ERR_PTR(-EINVAL);
10183 }
10184
10185 link = calloc(1, sizeof(*link));
10186 if (!link)
10187 return ERR_PTR(-ENOMEM);
10188 link->detach = &bpf_link__detach_fd;
10189
10190 pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
10191 if (pfd < 0) {
10192 pfd = -errno;
10193 free(link);
10194 pr_warn("prog '%s': failed to attach to raw tracepoint '%s': %s\n",
10195 prog->name, tp_name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
10196 return ERR_PTR(pfd);
10197 }
10198 link->fd = pfd;
10199 return link;
10200 }
10201
attach_raw_tp(const struct bpf_sec_def * sec,struct bpf_program * prog)10202 static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
10203 struct bpf_program *prog)
10204 {
10205 const char *tp_name = prog->sec_name + sec->len;
10206
10207 return bpf_program__attach_raw_tracepoint(prog, tp_name);
10208 }
10209
10210 /* Common logic for all BPF program types that attach to a btf_id */
bpf_program__attach_btf_id(struct bpf_program * prog)10211 static struct bpf_link *bpf_program__attach_btf_id(struct bpf_program *prog)
10212 {
10213 char errmsg[STRERR_BUFSIZE];
10214 struct bpf_link *link;
10215 int prog_fd, pfd;
10216
10217 prog_fd = bpf_program__fd(prog);
10218 if (prog_fd < 0) {
10219 pr_warn("prog '%s': can't attach before loaded\n", prog->name);
10220 return ERR_PTR(-EINVAL);
10221 }
10222
10223 link = calloc(1, sizeof(*link));
10224 if (!link)
10225 return ERR_PTR(-ENOMEM);
10226 link->detach = &bpf_link__detach_fd;
10227
10228 pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
10229 if (pfd < 0) {
10230 pfd = -errno;
10231 free(link);
10232 pr_warn("prog '%s': failed to attach: %s\n",
10233 prog->name, libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
10234 return ERR_PTR(pfd);
10235 }
10236 link->fd = pfd;
10237 return (struct bpf_link *)link;
10238 }
10239
bpf_program__attach_trace(struct bpf_program * prog)10240 struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
10241 {
10242 return bpf_program__attach_btf_id(prog);
10243 }
10244
bpf_program__attach_lsm(struct bpf_program * prog)10245 struct bpf_link *bpf_program__attach_lsm(struct bpf_program *prog)
10246 {
10247 return bpf_program__attach_btf_id(prog);
10248 }
10249
attach_trace(const struct bpf_sec_def * sec,struct bpf_program * prog)10250 static struct bpf_link *attach_trace(const struct bpf_sec_def *sec,
10251 struct bpf_program *prog)
10252 {
10253 return bpf_program__attach_trace(prog);
10254 }
10255
attach_lsm(const struct bpf_sec_def * sec,struct bpf_program * prog)10256 static struct bpf_link *attach_lsm(const struct bpf_sec_def *sec,
10257 struct bpf_program *prog)
10258 {
10259 return bpf_program__attach_lsm(prog);
10260 }
10261
attach_iter(const struct bpf_sec_def * sec,struct bpf_program * prog)10262 static struct bpf_link *attach_iter(const struct bpf_sec_def *sec,
10263 struct bpf_program *prog)
10264 {
10265 return bpf_program__attach_iter(prog, NULL);
10266 }
10267
10268 static struct bpf_link *
bpf_program__attach_fd(struct bpf_program * prog,int target_fd,int btf_id,const char * target_name)10269 bpf_program__attach_fd(struct bpf_program *prog, int target_fd, int btf_id,
10270 const char *target_name)
10271 {
10272 DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts,
10273 .target_btf_id = btf_id);
10274 enum bpf_attach_type attach_type;
10275 char errmsg[STRERR_BUFSIZE];
10276 struct bpf_link *link;
10277 int prog_fd, link_fd;
10278
10279 prog_fd = bpf_program__fd(prog);
10280 if (prog_fd < 0) {
10281 pr_warn("prog '%s': can't attach before loaded\n", prog->name);
10282 return ERR_PTR(-EINVAL);
10283 }
10284
10285 link = calloc(1, sizeof(*link));
10286 if (!link)
10287 return ERR_PTR(-ENOMEM);
10288 link->detach = &bpf_link__detach_fd;
10289
10290 attach_type = bpf_program__get_expected_attach_type(prog);
10291 link_fd = bpf_link_create(prog_fd, target_fd, attach_type, &opts);
10292 if (link_fd < 0) {
10293 link_fd = -errno;
10294 free(link);
10295 pr_warn("prog '%s': failed to attach to %s: %s\n",
10296 prog->name, target_name,
10297 libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
10298 return ERR_PTR(link_fd);
10299 }
10300 link->fd = link_fd;
10301 return link;
10302 }
10303
10304 struct bpf_link *
bpf_program__attach_cgroup(struct bpf_program * prog,int cgroup_fd)10305 bpf_program__attach_cgroup(struct bpf_program *prog, int cgroup_fd)
10306 {
10307 return bpf_program__attach_fd(prog, cgroup_fd, 0, "cgroup");
10308 }
10309
10310 struct bpf_link *
bpf_program__attach_netns(struct bpf_program * prog,int netns_fd)10311 bpf_program__attach_netns(struct bpf_program *prog, int netns_fd)
10312 {
10313 return bpf_program__attach_fd(prog, netns_fd, 0, "netns");
10314 }
10315
bpf_program__attach_xdp(struct bpf_program * prog,int ifindex)10316 struct bpf_link *bpf_program__attach_xdp(struct bpf_program *prog, int ifindex)
10317 {
10318 /* target_fd/target_ifindex use the same field in LINK_CREATE */
10319 return bpf_program__attach_fd(prog, ifindex, 0, "xdp");
10320 }
10321
bpf_program__attach_freplace(struct bpf_program * prog,int target_fd,const char * attach_func_name)10322 struct bpf_link *bpf_program__attach_freplace(struct bpf_program *prog,
10323 int target_fd,
10324 const char *attach_func_name)
10325 {
10326 int btf_id;
10327
10328 if (!!target_fd != !!attach_func_name) {
10329 pr_warn("prog '%s': supply none or both of target_fd and attach_func_name\n",
10330 prog->name);
10331 return ERR_PTR(-EINVAL);
10332 }
10333
10334 if (prog->type != BPF_PROG_TYPE_EXT) {
10335 pr_warn("prog '%s': only BPF_PROG_TYPE_EXT can attach as freplace",
10336 prog->name);
10337 return ERR_PTR(-EINVAL);
10338 }
10339
10340 if (target_fd) {
10341 btf_id = libbpf_find_prog_btf_id(attach_func_name, target_fd);
10342 if (btf_id < 0)
10343 return ERR_PTR(btf_id);
10344
10345 return bpf_program__attach_fd(prog, target_fd, btf_id, "freplace");
10346 } else {
10347 /* no target, so use raw_tracepoint_open for compatibility
10348 * with old kernels
10349 */
10350 return bpf_program__attach_trace(prog);
10351 }
10352 }
10353
10354 struct bpf_link *
bpf_program__attach_iter(struct bpf_program * prog,const struct bpf_iter_attach_opts * opts)10355 bpf_program__attach_iter(struct bpf_program *prog,
10356 const struct bpf_iter_attach_opts *opts)
10357 {
10358 DECLARE_LIBBPF_OPTS(bpf_link_create_opts, link_create_opts);
10359 char errmsg[STRERR_BUFSIZE];
10360 struct bpf_link *link;
10361 int prog_fd, link_fd;
10362 __u32 target_fd = 0;
10363
10364 if (!OPTS_VALID(opts, bpf_iter_attach_opts))
10365 return ERR_PTR(-EINVAL);
10366
10367 link_create_opts.iter_info = OPTS_GET(opts, link_info, (void *)0);
10368 link_create_opts.iter_info_len = OPTS_GET(opts, link_info_len, 0);
10369
10370 prog_fd = bpf_program__fd(prog);
10371 if (prog_fd < 0) {
10372 pr_warn("prog '%s': can't attach before loaded\n", prog->name);
10373 return ERR_PTR(-EINVAL);
10374 }
10375
10376 link = calloc(1, sizeof(*link));
10377 if (!link)
10378 return ERR_PTR(-ENOMEM);
10379 link->detach = &bpf_link__detach_fd;
10380
10381 link_fd = bpf_link_create(prog_fd, target_fd, BPF_TRACE_ITER,
10382 &link_create_opts);
10383 if (link_fd < 0) {
10384 link_fd = -errno;
10385 free(link);
10386 pr_warn("prog '%s': failed to attach to iterator: %s\n",
10387 prog->name, libbpf_strerror_r(link_fd, errmsg, sizeof(errmsg)));
10388 return ERR_PTR(link_fd);
10389 }
10390 link->fd = link_fd;
10391 return link;
10392 }
10393
bpf_program__attach(struct bpf_program * prog)10394 struct bpf_link *bpf_program__attach(struct bpf_program *prog)
10395 {
10396 const struct bpf_sec_def *sec_def;
10397
10398 sec_def = find_sec_def(prog->sec_name);
10399 if (!sec_def || !sec_def->attach_fn)
10400 return ERR_PTR(-ESRCH);
10401
10402 return sec_def->attach_fn(sec_def, prog);
10403 }
10404
bpf_link__detach_struct_ops(struct bpf_link * link)10405 static int bpf_link__detach_struct_ops(struct bpf_link *link)
10406 {
10407 __u32 zero = 0;
10408
10409 if (bpf_map_delete_elem(link->fd, &zero))
10410 return -errno;
10411
10412 return 0;
10413 }
10414
bpf_map__attach_struct_ops(struct bpf_map * map)10415 struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map)
10416 {
10417 struct bpf_struct_ops *st_ops;
10418 struct bpf_link *link;
10419 __u32 i, zero = 0;
10420 int err;
10421
10422 if (!bpf_map__is_struct_ops(map) || map->fd == -1)
10423 return ERR_PTR(-EINVAL);
10424
10425 link = calloc(1, sizeof(*link));
10426 if (!link)
10427 return ERR_PTR(-EINVAL);
10428
10429 st_ops = map->st_ops;
10430 for (i = 0; i < btf_vlen(st_ops->type); i++) {
10431 struct bpf_program *prog = st_ops->progs[i];
10432 void *kern_data;
10433 int prog_fd;
10434
10435 if (!prog)
10436 continue;
10437
10438 prog_fd = bpf_program__fd(prog);
10439 kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
10440 *(unsigned long *)kern_data = prog_fd;
10441 }
10442
10443 err = bpf_map_update_elem(map->fd, &zero, st_ops->kern_vdata, 0);
10444 if (err) {
10445 err = -errno;
10446 free(link);
10447 return ERR_PTR(err);
10448 }
10449
10450 link->detach = bpf_link__detach_struct_ops;
10451 link->fd = map->fd;
10452
10453 return link;
10454 }
10455
10456 enum bpf_perf_event_ret
bpf_perf_event_read_simple(void * mmap_mem,size_t mmap_size,size_t page_size,void ** copy_mem,size_t * copy_size,bpf_perf_event_print_t fn,void * private_data)10457 bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
10458 void **copy_mem, size_t *copy_size,
10459 bpf_perf_event_print_t fn, void *private_data)
10460 {
10461 struct perf_event_mmap_page *header = mmap_mem;
10462 __u64 data_head = ring_buffer_read_head(header);
10463 __u64 data_tail = header->data_tail;
10464 void *base = ((__u8 *)header) + page_size;
10465 int ret = LIBBPF_PERF_EVENT_CONT;
10466 struct perf_event_header *ehdr;
10467 size_t ehdr_size;
10468
10469 while (data_head != data_tail) {
10470 ehdr = base + (data_tail & (mmap_size - 1));
10471 ehdr_size = ehdr->size;
10472
10473 if (((void *)ehdr) + ehdr_size > base + mmap_size) {
10474 void *copy_start = ehdr;
10475 size_t len_first = base + mmap_size - copy_start;
10476 size_t len_secnd = ehdr_size - len_first;
10477
10478 if (*copy_size < ehdr_size) {
10479 free(*copy_mem);
10480 *copy_mem = malloc(ehdr_size);
10481 if (!*copy_mem) {
10482 *copy_size = 0;
10483 ret = LIBBPF_PERF_EVENT_ERROR;
10484 break;
10485 }
10486 *copy_size = ehdr_size;
10487 }
10488
10489 memcpy(*copy_mem, copy_start, len_first);
10490 memcpy(*copy_mem + len_first, base, len_secnd);
10491 ehdr = *copy_mem;
10492 }
10493
10494 ret = fn(ehdr, private_data);
10495 data_tail += ehdr_size;
10496 if (ret != LIBBPF_PERF_EVENT_CONT)
10497 break;
10498 }
10499
10500 ring_buffer_write_tail(header, data_tail);
10501 return ret;
10502 }
10503
10504 struct perf_buffer;
10505
10506 struct perf_buffer_params {
10507 struct perf_event_attr *attr;
10508 /* if event_cb is specified, it takes precendence */
10509 perf_buffer_event_fn event_cb;
10510 /* sample_cb and lost_cb are higher-level common-case callbacks */
10511 perf_buffer_sample_fn sample_cb;
10512 perf_buffer_lost_fn lost_cb;
10513 void *ctx;
10514 int cpu_cnt;
10515 int *cpus;
10516 int *map_keys;
10517 };
10518
10519 struct perf_cpu_buf {
10520 struct perf_buffer *pb;
10521 void *base; /* mmap()'ed memory */
10522 void *buf; /* for reconstructing segmented data */
10523 size_t buf_size;
10524 int fd;
10525 int cpu;
10526 int map_key;
10527 };
10528
10529 struct perf_buffer {
10530 perf_buffer_event_fn event_cb;
10531 perf_buffer_sample_fn sample_cb;
10532 perf_buffer_lost_fn lost_cb;
10533 void *ctx; /* passed into callbacks */
10534
10535 size_t page_size;
10536 size_t mmap_size;
10537 struct perf_cpu_buf **cpu_bufs;
10538 struct epoll_event *events;
10539 int cpu_cnt; /* number of allocated CPU buffers */
10540 int epoll_fd; /* perf event FD */
10541 int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
10542 };
10543
perf_buffer__free_cpu_buf(struct perf_buffer * pb,struct perf_cpu_buf * cpu_buf)10544 static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
10545 struct perf_cpu_buf *cpu_buf)
10546 {
10547 if (!cpu_buf)
10548 return;
10549 if (cpu_buf->base &&
10550 munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
10551 pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
10552 if (cpu_buf->fd >= 0) {
10553 ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
10554 close(cpu_buf->fd);
10555 }
10556 free(cpu_buf->buf);
10557 free(cpu_buf);
10558 }
10559
perf_buffer__free(struct perf_buffer * pb)10560 void perf_buffer__free(struct perf_buffer *pb)
10561 {
10562 int i;
10563
10564 if (IS_ERR_OR_NULL(pb))
10565 return;
10566 if (pb->cpu_bufs) {
10567 for (i = 0; i < pb->cpu_cnt; i++) {
10568 struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
10569
10570 if (!cpu_buf)
10571 continue;
10572
10573 bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
10574 perf_buffer__free_cpu_buf(pb, cpu_buf);
10575 }
10576 free(pb->cpu_bufs);
10577 }
10578 if (pb->epoll_fd >= 0)
10579 close(pb->epoll_fd);
10580 free(pb->events);
10581 free(pb);
10582 }
10583
10584 static struct perf_cpu_buf *
perf_buffer__open_cpu_buf(struct perf_buffer * pb,struct perf_event_attr * attr,int cpu,int map_key)10585 perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
10586 int cpu, int map_key)
10587 {
10588 struct perf_cpu_buf *cpu_buf;
10589 char msg[STRERR_BUFSIZE];
10590 int err;
10591
10592 cpu_buf = calloc(1, sizeof(*cpu_buf));
10593 if (!cpu_buf)
10594 return ERR_PTR(-ENOMEM);
10595
10596 cpu_buf->pb = pb;
10597 cpu_buf->cpu = cpu;
10598 cpu_buf->map_key = map_key;
10599
10600 cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
10601 -1, PERF_FLAG_FD_CLOEXEC);
10602 if (cpu_buf->fd < 0) {
10603 err = -errno;
10604 pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
10605 cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
10606 goto error;
10607 }
10608
10609 cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
10610 PROT_READ | PROT_WRITE, MAP_SHARED,
10611 cpu_buf->fd, 0);
10612 if (cpu_buf->base == MAP_FAILED) {
10613 cpu_buf->base = NULL;
10614 err = -errno;
10615 pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
10616 cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
10617 goto error;
10618 }
10619
10620 if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
10621 err = -errno;
10622 pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
10623 cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
10624 goto error;
10625 }
10626
10627 return cpu_buf;
10628
10629 error:
10630 perf_buffer__free_cpu_buf(pb, cpu_buf);
10631 return (struct perf_cpu_buf *)ERR_PTR(err);
10632 }
10633
10634 static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
10635 struct perf_buffer_params *p);
10636
perf_buffer__new(int map_fd,size_t page_cnt,const struct perf_buffer_opts * opts)10637 struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
10638 const struct perf_buffer_opts *opts)
10639 {
10640 struct perf_buffer_params p = {};
10641 struct perf_event_attr attr = { 0, };
10642
10643 attr.config = PERF_COUNT_SW_BPF_OUTPUT;
10644 attr.type = PERF_TYPE_SOFTWARE;
10645 attr.sample_type = PERF_SAMPLE_RAW;
10646 attr.sample_period = 1;
10647 attr.wakeup_events = 1;
10648
10649 p.attr = &attr;
10650 p.sample_cb = opts ? opts->sample_cb : NULL;
10651 p.lost_cb = opts ? opts->lost_cb : NULL;
10652 p.ctx = opts ? opts->ctx : NULL;
10653
10654 return __perf_buffer__new(map_fd, page_cnt, &p);
10655 }
10656
10657 struct perf_buffer *
perf_buffer__new_raw(int map_fd,size_t page_cnt,const struct perf_buffer_raw_opts * opts)10658 perf_buffer__new_raw(int map_fd, size_t page_cnt,
10659 const struct perf_buffer_raw_opts *opts)
10660 {
10661 struct perf_buffer_params p = {};
10662
10663 p.attr = opts->attr;
10664 p.event_cb = opts->event_cb;
10665 p.ctx = opts->ctx;
10666 p.cpu_cnt = opts->cpu_cnt;
10667 p.cpus = opts->cpus;
10668 p.map_keys = opts->map_keys;
10669
10670 return __perf_buffer__new(map_fd, page_cnt, &p);
10671 }
10672
__perf_buffer__new(int map_fd,size_t page_cnt,struct perf_buffer_params * p)10673 static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
10674 struct perf_buffer_params *p)
10675 {
10676 const char *online_cpus_file = "/sys/devices/system/cpu/online";
10677 struct bpf_map_info map;
10678 char msg[STRERR_BUFSIZE];
10679 struct perf_buffer *pb;
10680 bool *online = NULL;
10681 __u32 map_info_len;
10682 int err, i, j, n;
10683
10684 if (page_cnt & (page_cnt - 1)) {
10685 pr_warn("page count should be power of two, but is %zu\n",
10686 page_cnt);
10687 return ERR_PTR(-EINVAL);
10688 }
10689
10690 /* best-effort sanity checks */
10691 memset(&map, 0, sizeof(map));
10692 map_info_len = sizeof(map);
10693 err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
10694 if (err) {
10695 err = -errno;
10696 /* if BPF_OBJ_GET_INFO_BY_FD is supported, will return
10697 * -EBADFD, -EFAULT, or -E2BIG on real error
10698 */
10699 if (err != -EINVAL) {
10700 pr_warn("failed to get map info for map FD %d: %s\n",
10701 map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
10702 return ERR_PTR(err);
10703 }
10704 pr_debug("failed to get map info for FD %d; API not supported? Ignoring...\n",
10705 map_fd);
10706 } else {
10707 if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
10708 pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
10709 map.name);
10710 return ERR_PTR(-EINVAL);
10711 }
10712 }
10713
10714 pb = calloc(1, sizeof(*pb));
10715 if (!pb)
10716 return ERR_PTR(-ENOMEM);
10717
10718 pb->event_cb = p->event_cb;
10719 pb->sample_cb = p->sample_cb;
10720 pb->lost_cb = p->lost_cb;
10721 pb->ctx = p->ctx;
10722
10723 pb->page_size = getpagesize();
10724 pb->mmap_size = pb->page_size * page_cnt;
10725 pb->map_fd = map_fd;
10726
10727 pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
10728 if (pb->epoll_fd < 0) {
10729 err = -errno;
10730 pr_warn("failed to create epoll instance: %s\n",
10731 libbpf_strerror_r(err, msg, sizeof(msg)));
10732 goto error;
10733 }
10734
10735 if (p->cpu_cnt > 0) {
10736 pb->cpu_cnt = p->cpu_cnt;
10737 } else {
10738 pb->cpu_cnt = libbpf_num_possible_cpus();
10739 if (pb->cpu_cnt < 0) {
10740 err = pb->cpu_cnt;
10741 goto error;
10742 }
10743 if (map.max_entries && map.max_entries < pb->cpu_cnt)
10744 pb->cpu_cnt = map.max_entries;
10745 }
10746
10747 pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
10748 if (!pb->events) {
10749 err = -ENOMEM;
10750 pr_warn("failed to allocate events: out of memory\n");
10751 goto error;
10752 }
10753 pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
10754 if (!pb->cpu_bufs) {
10755 err = -ENOMEM;
10756 pr_warn("failed to allocate buffers: out of memory\n");
10757 goto error;
10758 }
10759
10760 err = parse_cpu_mask_file(online_cpus_file, &online, &n);
10761 if (err) {
10762 pr_warn("failed to get online CPU mask: %d\n", err);
10763 goto error;
10764 }
10765
10766 for (i = 0, j = 0; i < pb->cpu_cnt; i++) {
10767 struct perf_cpu_buf *cpu_buf;
10768 int cpu, map_key;
10769
10770 cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
10771 map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
10772
10773 /* in case user didn't explicitly requested particular CPUs to
10774 * be attached to, skip offline/not present CPUs
10775 */
10776 if (p->cpu_cnt <= 0 && (cpu >= n || !online[cpu]))
10777 continue;
10778
10779 cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
10780 if (IS_ERR(cpu_buf)) {
10781 err = PTR_ERR(cpu_buf);
10782 goto error;
10783 }
10784
10785 pb->cpu_bufs[j] = cpu_buf;
10786
10787 err = bpf_map_update_elem(pb->map_fd, &map_key,
10788 &cpu_buf->fd, 0);
10789 if (err) {
10790 err = -errno;
10791 pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
10792 cpu, map_key, cpu_buf->fd,
10793 libbpf_strerror_r(err, msg, sizeof(msg)));
10794 goto error;
10795 }
10796
10797 pb->events[j].events = EPOLLIN;
10798 pb->events[j].data.ptr = cpu_buf;
10799 if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
10800 &pb->events[j]) < 0) {
10801 err = -errno;
10802 pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
10803 cpu, cpu_buf->fd,
10804 libbpf_strerror_r(err, msg, sizeof(msg)));
10805 goto error;
10806 }
10807 j++;
10808 }
10809 pb->cpu_cnt = j;
10810 free(online);
10811
10812 return pb;
10813
10814 error:
10815 free(online);
10816 if (pb)
10817 perf_buffer__free(pb);
10818 return ERR_PTR(err);
10819 }
10820
10821 struct perf_sample_raw {
10822 struct perf_event_header header;
10823 uint32_t size;
10824 char data[];
10825 };
10826
10827 struct perf_sample_lost {
10828 struct perf_event_header header;
10829 uint64_t id;
10830 uint64_t lost;
10831 uint64_t sample_id;
10832 };
10833
10834 static enum bpf_perf_event_ret
perf_buffer__process_record(struct perf_event_header * e,void * ctx)10835 perf_buffer__process_record(struct perf_event_header *e, void *ctx)
10836 {
10837 struct perf_cpu_buf *cpu_buf = ctx;
10838 struct perf_buffer *pb = cpu_buf->pb;
10839 void *data = e;
10840
10841 /* user wants full control over parsing perf event */
10842 if (pb->event_cb)
10843 return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
10844
10845 switch (e->type) {
10846 case PERF_RECORD_SAMPLE: {
10847 struct perf_sample_raw *s = data;
10848
10849 if (pb->sample_cb)
10850 pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
10851 break;
10852 }
10853 case PERF_RECORD_LOST: {
10854 struct perf_sample_lost *s = data;
10855
10856 if (pb->lost_cb)
10857 pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
10858 break;
10859 }
10860 default:
10861 pr_warn("unknown perf sample type %d\n", e->type);
10862 return LIBBPF_PERF_EVENT_ERROR;
10863 }
10864 return LIBBPF_PERF_EVENT_CONT;
10865 }
10866
perf_buffer__process_records(struct perf_buffer * pb,struct perf_cpu_buf * cpu_buf)10867 static int perf_buffer__process_records(struct perf_buffer *pb,
10868 struct perf_cpu_buf *cpu_buf)
10869 {
10870 enum bpf_perf_event_ret ret;
10871
10872 ret = bpf_perf_event_read_simple(cpu_buf->base, pb->mmap_size,
10873 pb->page_size, &cpu_buf->buf,
10874 &cpu_buf->buf_size,
10875 perf_buffer__process_record, cpu_buf);
10876 if (ret != LIBBPF_PERF_EVENT_CONT)
10877 return ret;
10878 return 0;
10879 }
10880
perf_buffer__epoll_fd(const struct perf_buffer * pb)10881 int perf_buffer__epoll_fd(const struct perf_buffer *pb)
10882 {
10883 return pb->epoll_fd;
10884 }
10885
perf_buffer__poll(struct perf_buffer * pb,int timeout_ms)10886 int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
10887 {
10888 int i, cnt, err;
10889
10890 cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
10891 for (i = 0; i < cnt; i++) {
10892 struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
10893
10894 err = perf_buffer__process_records(pb, cpu_buf);
10895 if (err) {
10896 pr_warn("error while processing records: %d\n", err);
10897 return err;
10898 }
10899 }
10900 return cnt < 0 ? -errno : cnt;
10901 }
10902
10903 /* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer
10904 * manager.
10905 */
perf_buffer__buffer_cnt(const struct perf_buffer * pb)10906 size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb)
10907 {
10908 return pb->cpu_cnt;
10909 }
10910
10911 /*
10912 * Return perf_event FD of a ring buffer in *buf_idx* slot of
10913 * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using
10914 * select()/poll()/epoll() Linux syscalls.
10915 */
perf_buffer__buffer_fd(const struct perf_buffer * pb,size_t buf_idx)10916 int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx)
10917 {
10918 struct perf_cpu_buf *cpu_buf;
10919
10920 if (buf_idx >= pb->cpu_cnt)
10921 return -EINVAL;
10922
10923 cpu_buf = pb->cpu_bufs[buf_idx];
10924 if (!cpu_buf)
10925 return -ENOENT;
10926
10927 return cpu_buf->fd;
10928 }
10929
10930 /*
10931 * Consume data from perf ring buffer corresponding to slot *buf_idx* in
10932 * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to
10933 * consume, do nothing and return success.
10934 * Returns:
10935 * - 0 on success;
10936 * - <0 on failure.
10937 */
perf_buffer__consume_buffer(struct perf_buffer * pb,size_t buf_idx)10938 int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx)
10939 {
10940 struct perf_cpu_buf *cpu_buf;
10941
10942 if (buf_idx >= pb->cpu_cnt)
10943 return -EINVAL;
10944
10945 cpu_buf = pb->cpu_bufs[buf_idx];
10946 if (!cpu_buf)
10947 return -ENOENT;
10948
10949 return perf_buffer__process_records(pb, cpu_buf);
10950 }
10951
perf_buffer__consume(struct perf_buffer * pb)10952 int perf_buffer__consume(struct perf_buffer *pb)
10953 {
10954 int i, err;
10955
10956 for (i = 0; i < pb->cpu_cnt; i++) {
10957 struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
10958
10959 if (!cpu_buf)
10960 continue;
10961
10962 err = perf_buffer__process_records(pb, cpu_buf);
10963 if (err) {
10964 pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err);
10965 return err;
10966 }
10967 }
10968 return 0;
10969 }
10970
10971 struct bpf_prog_info_array_desc {
10972 int array_offset; /* e.g. offset of jited_prog_insns */
10973 int count_offset; /* e.g. offset of jited_prog_len */
10974 int size_offset; /* > 0: offset of rec size,
10975 * < 0: fix size of -size_offset
10976 */
10977 };
10978
10979 static struct bpf_prog_info_array_desc bpf_prog_info_array_desc[] = {
10980 [BPF_PROG_INFO_JITED_INSNS] = {
10981 offsetof(struct bpf_prog_info, jited_prog_insns),
10982 offsetof(struct bpf_prog_info, jited_prog_len),
10983 -1,
10984 },
10985 [BPF_PROG_INFO_XLATED_INSNS] = {
10986 offsetof(struct bpf_prog_info, xlated_prog_insns),
10987 offsetof(struct bpf_prog_info, xlated_prog_len),
10988 -1,
10989 },
10990 [BPF_PROG_INFO_MAP_IDS] = {
10991 offsetof(struct bpf_prog_info, map_ids),
10992 offsetof(struct bpf_prog_info, nr_map_ids),
10993 -(int)sizeof(__u32),
10994 },
10995 [BPF_PROG_INFO_JITED_KSYMS] = {
10996 offsetof(struct bpf_prog_info, jited_ksyms),
10997 offsetof(struct bpf_prog_info, nr_jited_ksyms),
10998 -(int)sizeof(__u64),
10999 },
11000 [BPF_PROG_INFO_JITED_FUNC_LENS] = {
11001 offsetof(struct bpf_prog_info, jited_func_lens),
11002 offsetof(struct bpf_prog_info, nr_jited_func_lens),
11003 -(int)sizeof(__u32),
11004 },
11005 [BPF_PROG_INFO_FUNC_INFO] = {
11006 offsetof(struct bpf_prog_info, func_info),
11007 offsetof(struct bpf_prog_info, nr_func_info),
11008 offsetof(struct bpf_prog_info, func_info_rec_size),
11009 },
11010 [BPF_PROG_INFO_LINE_INFO] = {
11011 offsetof(struct bpf_prog_info, line_info),
11012 offsetof(struct bpf_prog_info, nr_line_info),
11013 offsetof(struct bpf_prog_info, line_info_rec_size),
11014 },
11015 [BPF_PROG_INFO_JITED_LINE_INFO] = {
11016 offsetof(struct bpf_prog_info, jited_line_info),
11017 offsetof(struct bpf_prog_info, nr_jited_line_info),
11018 offsetof(struct bpf_prog_info, jited_line_info_rec_size),
11019 },
11020 [BPF_PROG_INFO_PROG_TAGS] = {
11021 offsetof(struct bpf_prog_info, prog_tags),
11022 offsetof(struct bpf_prog_info, nr_prog_tags),
11023 -(int)sizeof(__u8) * BPF_TAG_SIZE,
11024 },
11025
11026 };
11027
bpf_prog_info_read_offset_u32(struct bpf_prog_info * info,int offset)11028 static __u32 bpf_prog_info_read_offset_u32(struct bpf_prog_info *info,
11029 int offset)
11030 {
11031 __u32 *array = (__u32 *)info;
11032
11033 if (offset >= 0)
11034 return array[offset / sizeof(__u32)];
11035 return -(int)offset;
11036 }
11037
bpf_prog_info_read_offset_u64(struct bpf_prog_info * info,int offset)11038 static __u64 bpf_prog_info_read_offset_u64(struct bpf_prog_info *info,
11039 int offset)
11040 {
11041 __u64 *array = (__u64 *)info;
11042
11043 if (offset >= 0)
11044 return array[offset / sizeof(__u64)];
11045 return -(int)offset;
11046 }
11047
bpf_prog_info_set_offset_u32(struct bpf_prog_info * info,int offset,__u32 val)11048 static void bpf_prog_info_set_offset_u32(struct bpf_prog_info *info, int offset,
11049 __u32 val)
11050 {
11051 __u32 *array = (__u32 *)info;
11052
11053 if (offset >= 0)
11054 array[offset / sizeof(__u32)] = val;
11055 }
11056
bpf_prog_info_set_offset_u64(struct bpf_prog_info * info,int offset,__u64 val)11057 static void bpf_prog_info_set_offset_u64(struct bpf_prog_info *info, int offset,
11058 __u64 val)
11059 {
11060 __u64 *array = (__u64 *)info;
11061
11062 if (offset >= 0)
11063 array[offset / sizeof(__u64)] = val;
11064 }
11065
11066 struct bpf_prog_info_linear *
bpf_program__get_prog_info_linear(int fd,__u64 arrays)11067 bpf_program__get_prog_info_linear(int fd, __u64 arrays)
11068 {
11069 struct bpf_prog_info_linear *info_linear;
11070 struct bpf_prog_info info = {};
11071 __u32 info_len = sizeof(info);
11072 __u32 data_len = 0;
11073 int i, err;
11074 void *ptr;
11075
11076 if (arrays >> BPF_PROG_INFO_LAST_ARRAY)
11077 return ERR_PTR(-EINVAL);
11078
11079 /* step 1: get array dimensions */
11080 err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
11081 if (err) {
11082 pr_debug("can't get prog info: %s", strerror(errno));
11083 return ERR_PTR(-EFAULT);
11084 }
11085
11086 /* step 2: calculate total size of all arrays */
11087 for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
11088 bool include_array = (arrays & (1UL << i)) > 0;
11089 struct bpf_prog_info_array_desc *desc;
11090 __u32 count, size;
11091
11092 desc = bpf_prog_info_array_desc + i;
11093
11094 /* kernel is too old to support this field */
11095 if (info_len < desc->array_offset + sizeof(__u32) ||
11096 info_len < desc->count_offset + sizeof(__u32) ||
11097 (desc->size_offset > 0 && info_len < desc->size_offset))
11098 include_array = false;
11099
11100 if (!include_array) {
11101 arrays &= ~(1UL << i); /* clear the bit */
11102 continue;
11103 }
11104
11105 count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
11106 size = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
11107
11108 data_len += count * size;
11109 }
11110
11111 /* step 3: allocate continuous memory */
11112 data_len = roundup(data_len, sizeof(__u64));
11113 info_linear = malloc(sizeof(struct bpf_prog_info_linear) + data_len);
11114 if (!info_linear)
11115 return ERR_PTR(-ENOMEM);
11116
11117 /* step 4: fill data to info_linear->info */
11118 info_linear->arrays = arrays;
11119 memset(&info_linear->info, 0, sizeof(info));
11120 ptr = info_linear->data;
11121
11122 for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
11123 struct bpf_prog_info_array_desc *desc;
11124 __u32 count, size;
11125
11126 if ((arrays & (1UL << i)) == 0)
11127 continue;
11128
11129 desc = bpf_prog_info_array_desc + i;
11130 count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
11131 size = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
11132 bpf_prog_info_set_offset_u32(&info_linear->info,
11133 desc->count_offset, count);
11134 bpf_prog_info_set_offset_u32(&info_linear->info,
11135 desc->size_offset, size);
11136 bpf_prog_info_set_offset_u64(&info_linear->info,
11137 desc->array_offset,
11138 ptr_to_u64(ptr));
11139 ptr += count * size;
11140 }
11141
11142 /* step 5: call syscall again to get required arrays */
11143 err = bpf_obj_get_info_by_fd(fd, &info_linear->info, &info_len);
11144 if (err) {
11145 pr_debug("can't get prog info: %s", strerror(errno));
11146 free(info_linear);
11147 return ERR_PTR(-EFAULT);
11148 }
11149
11150 /* step 6: verify the data */
11151 for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
11152 struct bpf_prog_info_array_desc *desc;
11153 __u32 v1, v2;
11154
11155 if ((arrays & (1UL << i)) == 0)
11156 continue;
11157
11158 desc = bpf_prog_info_array_desc + i;
11159 v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
11160 v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
11161 desc->count_offset);
11162 if (v1 != v2)
11163 pr_warn("%s: mismatch in element count\n", __func__);
11164
11165 v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
11166 v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
11167 desc->size_offset);
11168 if (v1 != v2)
11169 pr_warn("%s: mismatch in rec size\n", __func__);
11170 }
11171
11172 /* step 7: update info_len and data_len */
11173 info_linear->info_len = sizeof(struct bpf_prog_info);
11174 info_linear->data_len = data_len;
11175
11176 return info_linear;
11177 }
11178
bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear * info_linear)11179 void bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear)
11180 {
11181 int i;
11182
11183 for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
11184 struct bpf_prog_info_array_desc *desc;
11185 __u64 addr, offs;
11186
11187 if ((info_linear->arrays & (1UL << i)) == 0)
11188 continue;
11189
11190 desc = bpf_prog_info_array_desc + i;
11191 addr = bpf_prog_info_read_offset_u64(&info_linear->info,
11192 desc->array_offset);
11193 offs = addr - ptr_to_u64(info_linear->data);
11194 bpf_prog_info_set_offset_u64(&info_linear->info,
11195 desc->array_offset, offs);
11196 }
11197 }
11198
bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear * info_linear)11199 void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
11200 {
11201 int i;
11202
11203 for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
11204 struct bpf_prog_info_array_desc *desc;
11205 __u64 addr, offs;
11206
11207 if ((info_linear->arrays & (1UL << i)) == 0)
11208 continue;
11209
11210 desc = bpf_prog_info_array_desc + i;
11211 offs = bpf_prog_info_read_offset_u64(&info_linear->info,
11212 desc->array_offset);
11213 addr = offs + ptr_to_u64(info_linear->data);
11214 bpf_prog_info_set_offset_u64(&info_linear->info,
11215 desc->array_offset, addr);
11216 }
11217 }
11218
bpf_program__set_attach_target(struct bpf_program * prog,int attach_prog_fd,const char * attach_func_name)11219 int bpf_program__set_attach_target(struct bpf_program *prog,
11220 int attach_prog_fd,
11221 const char *attach_func_name)
11222 {
11223 int btf_obj_fd = 0, btf_id = 0, err;
11224
11225 if (!prog || attach_prog_fd < 0 || !attach_func_name)
11226 return -EINVAL;
11227
11228 if (prog->obj->loaded)
11229 return -EINVAL;
11230
11231 if (attach_prog_fd) {
11232 btf_id = libbpf_find_prog_btf_id(attach_func_name,
11233 attach_prog_fd);
11234 if (btf_id < 0)
11235 return btf_id;
11236 } else {
11237 /* load btf_vmlinux, if not yet */
11238 err = bpf_object__load_vmlinux_btf(prog->obj, true);
11239 if (err)
11240 return err;
11241 err = find_kernel_btf_id(prog->obj, attach_func_name,
11242 prog->expected_attach_type,
11243 &btf_obj_fd, &btf_id);
11244 if (err)
11245 return err;
11246 }
11247
11248 prog->attach_btf_id = btf_id;
11249 prog->attach_btf_obj_fd = btf_obj_fd;
11250 prog->attach_prog_fd = attach_prog_fd;
11251 return 0;
11252 }
11253
parse_cpu_mask_str(const char * s,bool ** mask,int * mask_sz)11254 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz)
11255 {
11256 int err = 0, n, len, start, end = -1;
11257 bool *tmp;
11258
11259 *mask = NULL;
11260 *mask_sz = 0;
11261
11262 /* Each sub string separated by ',' has format \d+-\d+ or \d+ */
11263 while (*s) {
11264 if (*s == ',' || *s == '\n') {
11265 s++;
11266 continue;
11267 }
11268 n = sscanf(s, "%d%n-%d%n", &start, &len, &end, &len);
11269 if (n <= 0 || n > 2) {
11270 pr_warn("Failed to get CPU range %s: %d\n", s, n);
11271 err = -EINVAL;
11272 goto cleanup;
11273 } else if (n == 1) {
11274 end = start;
11275 }
11276 if (start < 0 || start > end) {
11277 pr_warn("Invalid CPU range [%d,%d] in %s\n",
11278 start, end, s);
11279 err = -EINVAL;
11280 goto cleanup;
11281 }
11282 tmp = realloc(*mask, end + 1);
11283 if (!tmp) {
11284 err = -ENOMEM;
11285 goto cleanup;
11286 }
11287 *mask = tmp;
11288 memset(tmp + *mask_sz, 0, start - *mask_sz);
11289 memset(tmp + start, 1, end - start + 1);
11290 *mask_sz = end + 1;
11291 s += len;
11292 }
11293 if (!*mask_sz) {
11294 pr_warn("Empty CPU range\n");
11295 return -EINVAL;
11296 }
11297 return 0;
11298 cleanup:
11299 free(*mask);
11300 *mask = NULL;
11301 return err;
11302 }
11303
parse_cpu_mask_file(const char * fcpu,bool ** mask,int * mask_sz)11304 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz)
11305 {
11306 int fd, err = 0, len;
11307 char buf[128];
11308
11309 fd = open(fcpu, O_RDONLY);
11310 if (fd < 0) {
11311 err = -errno;
11312 pr_warn("Failed to open cpu mask file %s: %d\n", fcpu, err);
11313 return err;
11314 }
11315 len = read(fd, buf, sizeof(buf));
11316 close(fd);
11317 if (len <= 0) {
11318 err = len ? -errno : -EINVAL;
11319 pr_warn("Failed to read cpu mask from %s: %d\n", fcpu, err);
11320 return err;
11321 }
11322 if (len >= sizeof(buf)) {
11323 pr_warn("CPU mask is too big in file %s\n", fcpu);
11324 return -E2BIG;
11325 }
11326 buf[len] = '\0';
11327
11328 return parse_cpu_mask_str(buf, mask, mask_sz);
11329 }
11330
libbpf_num_possible_cpus(void)11331 int libbpf_num_possible_cpus(void)
11332 {
11333 static const char *fcpu = "/sys/devices/system/cpu/possible";
11334 static int cpus;
11335 int err, n, i, tmp_cpus;
11336 bool *mask;
11337
11338 tmp_cpus = READ_ONCE(cpus);
11339 if (tmp_cpus > 0)
11340 return tmp_cpus;
11341
11342 err = parse_cpu_mask_file(fcpu, &mask, &n);
11343 if (err)
11344 return err;
11345
11346 tmp_cpus = 0;
11347 for (i = 0; i < n; i++) {
11348 if (mask[i])
11349 tmp_cpus++;
11350 }
11351 free(mask);
11352
11353 WRITE_ONCE(cpus, tmp_cpus);
11354 return tmp_cpus;
11355 }
11356
bpf_object__open_skeleton(struct bpf_object_skeleton * s,const struct bpf_object_open_opts * opts)11357 int bpf_object__open_skeleton(struct bpf_object_skeleton *s,
11358 const struct bpf_object_open_opts *opts)
11359 {
11360 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, skel_opts,
11361 .object_name = s->name,
11362 );
11363 struct bpf_object *obj;
11364 int i;
11365
11366 /* Attempt to preserve opts->object_name, unless overriden by user
11367 * explicitly. Overwriting object name for skeletons is discouraged,
11368 * as it breaks global data maps, because they contain object name
11369 * prefix as their own map name prefix. When skeleton is generated,
11370 * bpftool is making an assumption that this name will stay the same.
11371 */
11372 if (opts) {
11373 memcpy(&skel_opts, opts, sizeof(*opts));
11374 if (!opts->object_name)
11375 skel_opts.object_name = s->name;
11376 }
11377
11378 obj = bpf_object__open_mem(s->data, s->data_sz, &skel_opts);
11379 if (IS_ERR(obj)) {
11380 pr_warn("failed to initialize skeleton BPF object '%s': %ld\n",
11381 s->name, PTR_ERR(obj));
11382 return PTR_ERR(obj);
11383 }
11384
11385 *s->obj = obj;
11386
11387 for (i = 0; i < s->map_cnt; i++) {
11388 struct bpf_map **map = s->maps[i].map;
11389 const char *name = s->maps[i].name;
11390 void **mmaped = s->maps[i].mmaped;
11391
11392 *map = bpf_object__find_map_by_name(obj, name);
11393 if (!*map) {
11394 pr_warn("failed to find skeleton map '%s'\n", name);
11395 return -ESRCH;
11396 }
11397
11398 /* externs shouldn't be pre-setup from user code */
11399 if (mmaped && (*map)->libbpf_type != LIBBPF_MAP_KCONFIG)
11400 *mmaped = (*map)->mmaped;
11401 }
11402
11403 for (i = 0; i < s->prog_cnt; i++) {
11404 struct bpf_program **prog = s->progs[i].prog;
11405 const char *name = s->progs[i].name;
11406
11407 *prog = bpf_object__find_program_by_name(obj, name);
11408 if (!*prog) {
11409 pr_warn("failed to find skeleton program '%s'\n", name);
11410 return -ESRCH;
11411 }
11412 }
11413
11414 return 0;
11415 }
11416
bpf_object__load_skeleton(struct bpf_object_skeleton * s)11417 int bpf_object__load_skeleton(struct bpf_object_skeleton *s)
11418 {
11419 int i, err;
11420
11421 err = bpf_object__load(*s->obj);
11422 if (err) {
11423 pr_warn("failed to load BPF skeleton '%s': %d\n", s->name, err);
11424 return err;
11425 }
11426
11427 for (i = 0; i < s->map_cnt; i++) {
11428 struct bpf_map *map = *s->maps[i].map;
11429 size_t mmap_sz = bpf_map_mmap_sz(map);
11430 int prot, map_fd = bpf_map__fd(map);
11431 void **mmaped = s->maps[i].mmaped;
11432
11433 if (!mmaped)
11434 continue;
11435
11436 if (!(map->def.map_flags & BPF_F_MMAPABLE)) {
11437 *mmaped = NULL;
11438 continue;
11439 }
11440
11441 if (map->def.map_flags & BPF_F_RDONLY_PROG)
11442 prot = PROT_READ;
11443 else
11444 prot = PROT_READ | PROT_WRITE;
11445
11446 /* Remap anonymous mmap()-ed "map initialization image" as
11447 * a BPF map-backed mmap()-ed memory, but preserving the same
11448 * memory address. This will cause kernel to change process'
11449 * page table to point to a different piece of kernel memory,
11450 * but from userspace point of view memory address (and its
11451 * contents, being identical at this point) will stay the
11452 * same. This mapping will be released by bpf_object__close()
11453 * as per normal clean up procedure, so we don't need to worry
11454 * about it from skeleton's clean up perspective.
11455 */
11456 *mmaped = mmap(map->mmaped, mmap_sz, prot,
11457 MAP_SHARED | MAP_FIXED, map_fd, 0);
11458 if (*mmaped == MAP_FAILED) {
11459 err = -errno;
11460 *mmaped = NULL;
11461 pr_warn("failed to re-mmap() map '%s': %d\n",
11462 bpf_map__name(map), err);
11463 return err;
11464 }
11465 }
11466
11467 return 0;
11468 }
11469
bpf_object__attach_skeleton(struct bpf_object_skeleton * s)11470 int bpf_object__attach_skeleton(struct bpf_object_skeleton *s)
11471 {
11472 int i;
11473
11474 for (i = 0; i < s->prog_cnt; i++) {
11475 struct bpf_program *prog = *s->progs[i].prog;
11476 struct bpf_link **link = s->progs[i].link;
11477 const struct bpf_sec_def *sec_def;
11478
11479 if (!prog->load)
11480 continue;
11481
11482 sec_def = find_sec_def(prog->sec_name);
11483 if (!sec_def || !sec_def->attach_fn)
11484 continue;
11485
11486 *link = sec_def->attach_fn(sec_def, prog);
11487 if (IS_ERR(*link)) {
11488 pr_warn("failed to auto-attach program '%s': %ld\n",
11489 bpf_program__name(prog), PTR_ERR(*link));
11490 return PTR_ERR(*link);
11491 }
11492 }
11493
11494 return 0;
11495 }
11496
bpf_object__detach_skeleton(struct bpf_object_skeleton * s)11497 void bpf_object__detach_skeleton(struct bpf_object_skeleton *s)
11498 {
11499 int i;
11500
11501 for (i = 0; i < s->prog_cnt; i++) {
11502 struct bpf_link **link = s->progs[i].link;
11503
11504 bpf_link__destroy(*link);
11505 *link = NULL;
11506 }
11507 }
11508
bpf_object__destroy_skeleton(struct bpf_object_skeleton * s)11509 void bpf_object__destroy_skeleton(struct bpf_object_skeleton *s)
11510 {
11511 if (s->progs)
11512 bpf_object__detach_skeleton(s);
11513 if (s->obj)
11514 bpf_object__close(*s->obj);
11515 free(s->maps);
11516 free(s->progs);
11517 free(s);
11518 }
11519