1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (c) 2018 Facebook */
3
4 #include <uapi/linux/btf.h>
5 #include <uapi/linux/bpf.h>
6 #include <uapi/linux/bpf_perf_event.h>
7 #include <uapi/linux/types.h>
8 #include <linux/seq_file.h>
9 #include <linux/compiler.h>
10 #include <linux/ctype.h>
11 #include <linux/errno.h>
12 #include <linux/slab.h>
13 #include <linux/anon_inodes.h>
14 #include <linux/file.h>
15 #include <linux/uaccess.h>
16 #include <linux/kernel.h>
17 #include <linux/idr.h>
18 #include <linux/sort.h>
19 #include <linux/bpf_verifier.h>
20 #include <linux/btf.h>
21 #include <linux/btf_ids.h>
22 #include <linux/bpf.h>
23 #include <linux/bpf_lsm.h>
24 #include <linux/skmsg.h>
25 #include <linux/perf_event.h>
26 #include <linux/bsearch.h>
27 #include <linux/kobject.h>
28 #include <linux/sysfs.h>
29
30 #include <net/netfilter/nf_bpf_link.h>
31
32 #include <net/sock.h>
33 #include <net/xdp.h>
34 #include "../tools/lib/bpf/relo_core.h"
35
36 /* BTF (BPF Type Format) is the meta data format which describes
37 * the data types of BPF program/map. Hence, it basically focus
38 * on the C programming language which the modern BPF is primary
39 * using.
40 *
41 * ELF Section:
42 * ~~~~~~~~~~~
43 * The BTF data is stored under the ".BTF" ELF section
44 *
45 * struct btf_type:
46 * ~~~~~~~~~~~~~~~
47 * Each 'struct btf_type' object describes a C data type.
48 * Depending on the type it is describing, a 'struct btf_type'
49 * object may be followed by more data. F.e.
50 * To describe an array, 'struct btf_type' is followed by
51 * 'struct btf_array'.
52 *
53 * 'struct btf_type' and any extra data following it are
54 * 4 bytes aligned.
55 *
56 * Type section:
57 * ~~~~~~~~~~~~~
58 * The BTF type section contains a list of 'struct btf_type' objects.
59 * Each one describes a C type. Recall from the above section
60 * that a 'struct btf_type' object could be immediately followed by extra
61 * data in order to describe some particular C types.
62 *
63 * type_id:
64 * ~~~~~~~
65 * Each btf_type object is identified by a type_id. The type_id
66 * is implicitly implied by the location of the btf_type object in
67 * the BTF type section. The first one has type_id 1. The second
68 * one has type_id 2...etc. Hence, an earlier btf_type has
69 * a smaller type_id.
70 *
71 * A btf_type object may refer to another btf_type object by using
72 * type_id (i.e. the "type" in the "struct btf_type").
73 *
74 * NOTE that we cannot assume any reference-order.
75 * A btf_type object can refer to an earlier btf_type object
76 * but it can also refer to a later btf_type object.
77 *
78 * For example, to describe "const void *". A btf_type
79 * object describing "const" may refer to another btf_type
80 * object describing "void *". This type-reference is done
81 * by specifying type_id:
82 *
83 * [1] CONST (anon) type_id=2
84 * [2] PTR (anon) type_id=0
85 *
86 * The above is the btf_verifier debug log:
87 * - Each line started with "[?]" is a btf_type object
88 * - [?] is the type_id of the btf_type object.
89 * - CONST/PTR is the BTF_KIND_XXX
90 * - "(anon)" is the name of the type. It just
91 * happens that CONST and PTR has no name.
92 * - type_id=XXX is the 'u32 type' in btf_type
93 *
94 * NOTE: "void" has type_id 0
95 *
96 * String section:
97 * ~~~~~~~~~~~~~~
98 * The BTF string section contains the names used by the type section.
99 * Each string is referred by an "offset" from the beginning of the
100 * string section.
101 *
102 * Each string is '\0' terminated.
103 *
104 * The first character in the string section must be '\0'
105 * which is used to mean 'anonymous'. Some btf_type may not
106 * have a name.
107 */
108
109 /* BTF verification:
110 *
111 * To verify BTF data, two passes are needed.
112 *
113 * Pass #1
114 * ~~~~~~~
115 * The first pass is to collect all btf_type objects to
116 * an array: "btf->types".
117 *
118 * Depending on the C type that a btf_type is describing,
119 * a btf_type may be followed by extra data. We don't know
120 * how many btf_type is there, and more importantly we don't
121 * know where each btf_type is located in the type section.
122 *
123 * Without knowing the location of each type_id, most verifications
124 * cannot be done. e.g. an earlier btf_type may refer to a later
125 * btf_type (recall the "const void *" above), so we cannot
126 * check this type-reference in the first pass.
127 *
128 * In the first pass, it still does some verifications (e.g.
129 * checking the name is a valid offset to the string section).
130 *
131 * Pass #2
132 * ~~~~~~~
133 * The main focus is to resolve a btf_type that is referring
134 * to another type.
135 *
136 * We have to ensure the referring type:
137 * 1) does exist in the BTF (i.e. in btf->types[])
138 * 2) does not cause a loop:
139 * struct A {
140 * struct B b;
141 * };
142 *
143 * struct B {
144 * struct A a;
145 * };
146 *
147 * btf_type_needs_resolve() decides if a btf_type needs
148 * to be resolved.
149 *
150 * The needs_resolve type implements the "resolve()" ops which
151 * essentially does a DFS and detects backedge.
152 *
153 * During resolve (or DFS), different C types have different
154 * "RESOLVED" conditions.
155 *
156 * When resolving a BTF_KIND_STRUCT, we need to resolve all its
157 * members because a member is always referring to another
158 * type. A struct's member can be treated as "RESOLVED" if
159 * it is referring to a BTF_KIND_PTR. Otherwise, the
160 * following valid C struct would be rejected:
161 *
162 * struct A {
163 * int m;
164 * struct A *a;
165 * };
166 *
167 * When resolving a BTF_KIND_PTR, it needs to keep resolving if
168 * it is referring to another BTF_KIND_PTR. Otherwise, we cannot
169 * detect a pointer loop, e.g.:
170 * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
171 * ^ |
172 * +-----------------------------------------+
173 *
174 */
175
176 #define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
177 #define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
178 #define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
179 #define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
180 #define BITS_ROUNDUP_BYTES(bits) \
181 (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
182
183 #define BTF_INFO_MASK 0x9f00ffff
184 #define BTF_INT_MASK 0x0fffffff
185 #define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
186 #define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
187
188 /* 16MB for 64k structs and each has 16 members and
189 * a few MB spaces for the string section.
190 * The hard limit is S32_MAX.
191 */
192 #define BTF_MAX_SIZE (16 * 1024 * 1024)
193
194 #define for_each_member_from(i, from, struct_type, member) \
195 for (i = from, member = btf_type_member(struct_type) + from; \
196 i < btf_type_vlen(struct_type); \
197 i++, member++)
198
199 #define for_each_vsi_from(i, from, struct_type, member) \
200 for (i = from, member = btf_type_var_secinfo(struct_type) + from; \
201 i < btf_type_vlen(struct_type); \
202 i++, member++)
203
204 DEFINE_IDR(btf_idr);
205 DEFINE_SPINLOCK(btf_idr_lock);
206
207 enum btf_kfunc_hook {
208 BTF_KFUNC_HOOK_COMMON,
209 BTF_KFUNC_HOOK_XDP,
210 BTF_KFUNC_HOOK_TC,
211 BTF_KFUNC_HOOK_STRUCT_OPS,
212 BTF_KFUNC_HOOK_TRACING,
213 BTF_KFUNC_HOOK_SYSCALL,
214 BTF_KFUNC_HOOK_FMODRET,
215 BTF_KFUNC_HOOK_CGROUP_SKB,
216 BTF_KFUNC_HOOK_SCHED_ACT,
217 BTF_KFUNC_HOOK_SK_SKB,
218 BTF_KFUNC_HOOK_SOCKET_FILTER,
219 BTF_KFUNC_HOOK_LWT,
220 BTF_KFUNC_HOOK_NETFILTER,
221 BTF_KFUNC_HOOK_KPROBE,
222 BTF_KFUNC_HOOK_MAX,
223 };
224
225 enum {
226 BTF_KFUNC_SET_MAX_CNT = 256,
227 BTF_DTOR_KFUNC_MAX_CNT = 256,
228 BTF_KFUNC_FILTER_MAX_CNT = 16,
229 };
230
231 struct btf_kfunc_hook_filter {
232 btf_kfunc_filter_t filters[BTF_KFUNC_FILTER_MAX_CNT];
233 u32 nr_filters;
234 };
235
236 struct btf_kfunc_set_tab {
237 struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
238 struct btf_kfunc_hook_filter hook_filters[BTF_KFUNC_HOOK_MAX];
239 };
240
241 struct btf_id_dtor_kfunc_tab {
242 u32 cnt;
243 struct btf_id_dtor_kfunc dtors[];
244 };
245
246 struct btf_struct_ops_tab {
247 u32 cnt;
248 u32 capacity;
249 struct bpf_struct_ops_desc ops[];
250 };
251
252 struct btf {
253 void *data;
254 struct btf_type **types;
255 u32 *resolved_ids;
256 u32 *resolved_sizes;
257 const char *strings;
258 void *nohdr_data;
259 struct btf_header hdr;
260 u32 nr_types; /* includes VOID for base BTF */
261 u32 types_size;
262 u32 data_size;
263 refcount_t refcnt;
264 u32 id;
265 struct rcu_head rcu;
266 struct btf_kfunc_set_tab *kfunc_set_tab;
267 struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;
268 struct btf_struct_metas *struct_meta_tab;
269 struct btf_struct_ops_tab *struct_ops_tab;
270
271 /* split BTF support */
272 struct btf *base_btf;
273 u32 start_id; /* first type ID in this BTF (0 for base BTF) */
274 u32 start_str_off; /* first string offset (0 for base BTF) */
275 char name[MODULE_NAME_LEN];
276 bool kernel_btf;
277 };
278
279 enum verifier_phase {
280 CHECK_META,
281 CHECK_TYPE,
282 };
283
284 struct resolve_vertex {
285 const struct btf_type *t;
286 u32 type_id;
287 u16 next_member;
288 };
289
290 enum visit_state {
291 NOT_VISITED,
292 VISITED,
293 RESOLVED,
294 };
295
296 enum resolve_mode {
297 RESOLVE_TBD, /* To Be Determined */
298 RESOLVE_PTR, /* Resolving for Pointer */
299 RESOLVE_STRUCT_OR_ARRAY, /* Resolving for struct/union
300 * or array
301 */
302 };
303
304 #define MAX_RESOLVE_DEPTH 32
305
306 struct btf_sec_info {
307 u32 off;
308 u32 len;
309 };
310
311 struct btf_verifier_env {
312 struct btf *btf;
313 u8 *visit_states;
314 struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
315 struct bpf_verifier_log log;
316 u32 log_type_id;
317 u32 top_stack;
318 enum verifier_phase phase;
319 enum resolve_mode resolve_mode;
320 };
321
322 static const char * const btf_kind_str[NR_BTF_KINDS] = {
323 [BTF_KIND_UNKN] = "UNKNOWN",
324 [BTF_KIND_INT] = "INT",
325 [BTF_KIND_PTR] = "PTR",
326 [BTF_KIND_ARRAY] = "ARRAY",
327 [BTF_KIND_STRUCT] = "STRUCT",
328 [BTF_KIND_UNION] = "UNION",
329 [BTF_KIND_ENUM] = "ENUM",
330 [BTF_KIND_FWD] = "FWD",
331 [BTF_KIND_TYPEDEF] = "TYPEDEF",
332 [BTF_KIND_VOLATILE] = "VOLATILE",
333 [BTF_KIND_CONST] = "CONST",
334 [BTF_KIND_RESTRICT] = "RESTRICT",
335 [BTF_KIND_FUNC] = "FUNC",
336 [BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
337 [BTF_KIND_VAR] = "VAR",
338 [BTF_KIND_DATASEC] = "DATASEC",
339 [BTF_KIND_FLOAT] = "FLOAT",
340 [BTF_KIND_DECL_TAG] = "DECL_TAG",
341 [BTF_KIND_TYPE_TAG] = "TYPE_TAG",
342 [BTF_KIND_ENUM64] = "ENUM64",
343 };
344
btf_type_str(const struct btf_type * t)345 const char *btf_type_str(const struct btf_type *t)
346 {
347 return btf_kind_str[BTF_INFO_KIND(t->info)];
348 }
349
350 /* Chunk size we use in safe copy of data to be shown. */
351 #define BTF_SHOW_OBJ_SAFE_SIZE 32
352
353 /*
354 * This is the maximum size of a base type value (equivalent to a
355 * 128-bit int); if we are at the end of our safe buffer and have
356 * less than 16 bytes space we can't be assured of being able
357 * to copy the next type safely, so in such cases we will initiate
358 * a new copy.
359 */
360 #define BTF_SHOW_OBJ_BASE_TYPE_SIZE 16
361
362 /* Type name size */
363 #define BTF_SHOW_NAME_SIZE 80
364
365 /*
366 * The suffix of a type that indicates it cannot alias another type when
367 * comparing BTF IDs for kfunc invocations.
368 */
369 #define NOCAST_ALIAS_SUFFIX "___init"
370
371 /*
372 * Common data to all BTF show operations. Private show functions can add
373 * their own data to a structure containing a struct btf_show and consult it
374 * in the show callback. See btf_type_show() below.
375 *
376 * One challenge with showing nested data is we want to skip 0-valued
377 * data, but in order to figure out whether a nested object is all zeros
378 * we need to walk through it. As a result, we need to make two passes
379 * when handling structs, unions and arrays; the first path simply looks
380 * for nonzero data, while the second actually does the display. The first
381 * pass is signalled by show->state.depth_check being set, and if we
382 * encounter a non-zero value we set show->state.depth_to_show to
383 * the depth at which we encountered it. When we have completed the
384 * first pass, we will know if anything needs to be displayed if
385 * depth_to_show > depth. See btf_[struct,array]_show() for the
386 * implementation of this.
387 *
388 * Another problem is we want to ensure the data for display is safe to
389 * access. To support this, the anonymous "struct {} obj" tracks the data
390 * object and our safe copy of it. We copy portions of the data needed
391 * to the object "copy" buffer, but because its size is limited to
392 * BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
393 * traverse larger objects for display.
394 *
395 * The various data type show functions all start with a call to
396 * btf_show_start_type() which returns a pointer to the safe copy
397 * of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
398 * raw data itself). btf_show_obj_safe() is responsible for
399 * using copy_from_kernel_nofault() to update the safe data if necessary
400 * as we traverse the object's data. skbuff-like semantics are
401 * used:
402 *
403 * - obj.head points to the start of the toplevel object for display
404 * - obj.size is the size of the toplevel object
405 * - obj.data points to the current point in the original data at
406 * which our safe data starts. obj.data will advance as we copy
407 * portions of the data.
408 *
409 * In most cases a single copy will suffice, but larger data structures
410 * such as "struct task_struct" will require many copies. The logic in
411 * btf_show_obj_safe() handles the logic that determines if a new
412 * copy_from_kernel_nofault() is needed.
413 */
414 struct btf_show {
415 u64 flags;
416 void *target; /* target of show operation (seq file, buffer) */
417 void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
418 const struct btf *btf;
419 /* below are used during iteration */
420 struct {
421 u8 depth;
422 u8 depth_to_show;
423 u8 depth_check;
424 u8 array_member:1,
425 array_terminated:1;
426 u16 array_encoding;
427 u32 type_id;
428 int status; /* non-zero for error */
429 const struct btf_type *type;
430 const struct btf_member *member;
431 char name[BTF_SHOW_NAME_SIZE]; /* space for member name/type */
432 } state;
433 struct {
434 u32 size;
435 void *head;
436 void *data;
437 u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
438 } obj;
439 };
440
441 struct btf_kind_operations {
442 s32 (*check_meta)(struct btf_verifier_env *env,
443 const struct btf_type *t,
444 u32 meta_left);
445 int (*resolve)(struct btf_verifier_env *env,
446 const struct resolve_vertex *v);
447 int (*check_member)(struct btf_verifier_env *env,
448 const struct btf_type *struct_type,
449 const struct btf_member *member,
450 const struct btf_type *member_type);
451 int (*check_kflag_member)(struct btf_verifier_env *env,
452 const struct btf_type *struct_type,
453 const struct btf_member *member,
454 const struct btf_type *member_type);
455 void (*log_details)(struct btf_verifier_env *env,
456 const struct btf_type *t);
457 void (*show)(const struct btf *btf, const struct btf_type *t,
458 u32 type_id, void *data, u8 bits_offsets,
459 struct btf_show *show);
460 };
461
462 static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
463 static struct btf_type btf_void;
464
465 static int btf_resolve(struct btf_verifier_env *env,
466 const struct btf_type *t, u32 type_id);
467
468 static int btf_func_check(struct btf_verifier_env *env,
469 const struct btf_type *t);
470
btf_type_is_modifier(const struct btf_type * t)471 static bool btf_type_is_modifier(const struct btf_type *t)
472 {
473 /* Some of them is not strictly a C modifier
474 * but they are grouped into the same bucket
475 * for BTF concern:
476 * A type (t) that refers to another
477 * type through t->type AND its size cannot
478 * be determined without following the t->type.
479 *
480 * ptr does not fall into this bucket
481 * because its size is always sizeof(void *).
482 */
483 switch (BTF_INFO_KIND(t->info)) {
484 case BTF_KIND_TYPEDEF:
485 case BTF_KIND_VOLATILE:
486 case BTF_KIND_CONST:
487 case BTF_KIND_RESTRICT:
488 case BTF_KIND_TYPE_TAG:
489 return true;
490 }
491
492 return false;
493 }
494
btf_type_is_void(const struct btf_type * t)495 bool btf_type_is_void(const struct btf_type *t)
496 {
497 return t == &btf_void;
498 }
499
btf_type_is_fwd(const struct btf_type * t)500 static bool btf_type_is_fwd(const struct btf_type *t)
501 {
502 return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
503 }
504
btf_type_is_datasec(const struct btf_type * t)505 static bool btf_type_is_datasec(const struct btf_type *t)
506 {
507 return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
508 }
509
btf_type_is_decl_tag(const struct btf_type * t)510 static bool btf_type_is_decl_tag(const struct btf_type *t)
511 {
512 return BTF_INFO_KIND(t->info) == BTF_KIND_DECL_TAG;
513 }
514
btf_type_nosize(const struct btf_type * t)515 static bool btf_type_nosize(const struct btf_type *t)
516 {
517 return btf_type_is_void(t) || btf_type_is_fwd(t) ||
518 btf_type_is_func(t) || btf_type_is_func_proto(t) ||
519 btf_type_is_decl_tag(t);
520 }
521
btf_type_nosize_or_null(const struct btf_type * t)522 static bool btf_type_nosize_or_null(const struct btf_type *t)
523 {
524 return !t || btf_type_nosize(t);
525 }
526
btf_type_is_decl_tag_target(const struct btf_type * t)527 static bool btf_type_is_decl_tag_target(const struct btf_type *t)
528 {
529 return btf_type_is_func(t) || btf_type_is_struct(t) ||
530 btf_type_is_var(t) || btf_type_is_typedef(t);
531 }
532
btf_nr_types(const struct btf * btf)533 u32 btf_nr_types(const struct btf *btf)
534 {
535 u32 total = 0;
536
537 while (btf) {
538 total += btf->nr_types;
539 btf = btf->base_btf;
540 }
541
542 return total;
543 }
544
btf_find_by_name_kind(const struct btf * btf,const char * name,u8 kind)545 s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
546 {
547 const struct btf_type *t;
548 const char *tname;
549 u32 i, total;
550
551 total = btf_nr_types(btf);
552 for (i = 1; i < total; i++) {
553 t = btf_type_by_id(btf, i);
554 if (BTF_INFO_KIND(t->info) != kind)
555 continue;
556
557 tname = btf_name_by_offset(btf, t->name_off);
558 if (!strcmp(tname, name))
559 return i;
560 }
561
562 return -ENOENT;
563 }
564
bpf_find_btf_id(const char * name,u32 kind,struct btf ** btf_p)565 s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
566 {
567 struct btf *btf;
568 s32 ret;
569 int id;
570
571 btf = bpf_get_btf_vmlinux();
572 if (IS_ERR(btf))
573 return PTR_ERR(btf);
574 if (!btf)
575 return -EINVAL;
576
577 ret = btf_find_by_name_kind(btf, name, kind);
578 /* ret is never zero, since btf_find_by_name_kind returns
579 * positive btf_id or negative error.
580 */
581 if (ret > 0) {
582 btf_get(btf);
583 *btf_p = btf;
584 return ret;
585 }
586
587 /* If name is not found in vmlinux's BTF then search in module's BTFs */
588 spin_lock_bh(&btf_idr_lock);
589 idr_for_each_entry(&btf_idr, btf, id) {
590 if (!btf_is_module(btf))
591 continue;
592 /* linear search could be slow hence unlock/lock
593 * the IDR to avoiding holding it for too long
594 */
595 btf_get(btf);
596 spin_unlock_bh(&btf_idr_lock);
597 ret = btf_find_by_name_kind(btf, name, kind);
598 if (ret > 0) {
599 *btf_p = btf;
600 return ret;
601 }
602 btf_put(btf);
603 spin_lock_bh(&btf_idr_lock);
604 }
605 spin_unlock_bh(&btf_idr_lock);
606 return ret;
607 }
608
btf_type_skip_modifiers(const struct btf * btf,u32 id,u32 * res_id)609 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
610 u32 id, u32 *res_id)
611 {
612 const struct btf_type *t = btf_type_by_id(btf, id);
613
614 while (btf_type_is_modifier(t)) {
615 id = t->type;
616 t = btf_type_by_id(btf, t->type);
617 }
618
619 if (res_id)
620 *res_id = id;
621
622 return t;
623 }
624
btf_type_resolve_ptr(const struct btf * btf,u32 id,u32 * res_id)625 const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
626 u32 id, u32 *res_id)
627 {
628 const struct btf_type *t;
629
630 t = btf_type_skip_modifiers(btf, id, NULL);
631 if (!btf_type_is_ptr(t))
632 return NULL;
633
634 return btf_type_skip_modifiers(btf, t->type, res_id);
635 }
636
btf_type_resolve_func_ptr(const struct btf * btf,u32 id,u32 * res_id)637 const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
638 u32 id, u32 *res_id)
639 {
640 const struct btf_type *ptype;
641
642 ptype = btf_type_resolve_ptr(btf, id, res_id);
643 if (ptype && btf_type_is_func_proto(ptype))
644 return ptype;
645
646 return NULL;
647 }
648
649 /* Types that act only as a source, not sink or intermediate
650 * type when resolving.
651 */
btf_type_is_resolve_source_only(const struct btf_type * t)652 static bool btf_type_is_resolve_source_only(const struct btf_type *t)
653 {
654 return btf_type_is_var(t) ||
655 btf_type_is_decl_tag(t) ||
656 btf_type_is_datasec(t);
657 }
658
659 /* What types need to be resolved?
660 *
661 * btf_type_is_modifier() is an obvious one.
662 *
663 * btf_type_is_struct() because its member refers to
664 * another type (through member->type).
665 *
666 * btf_type_is_var() because the variable refers to
667 * another type. btf_type_is_datasec() holds multiple
668 * btf_type_is_var() types that need resolving.
669 *
670 * btf_type_is_array() because its element (array->type)
671 * refers to another type. Array can be thought of a
672 * special case of struct while array just has the same
673 * member-type repeated by array->nelems of times.
674 */
btf_type_needs_resolve(const struct btf_type * t)675 static bool btf_type_needs_resolve(const struct btf_type *t)
676 {
677 return btf_type_is_modifier(t) ||
678 btf_type_is_ptr(t) ||
679 btf_type_is_struct(t) ||
680 btf_type_is_array(t) ||
681 btf_type_is_var(t) ||
682 btf_type_is_func(t) ||
683 btf_type_is_decl_tag(t) ||
684 btf_type_is_datasec(t);
685 }
686
687 /* t->size can be used */
btf_type_has_size(const struct btf_type * t)688 static bool btf_type_has_size(const struct btf_type *t)
689 {
690 switch (BTF_INFO_KIND(t->info)) {
691 case BTF_KIND_INT:
692 case BTF_KIND_STRUCT:
693 case BTF_KIND_UNION:
694 case BTF_KIND_ENUM:
695 case BTF_KIND_DATASEC:
696 case BTF_KIND_FLOAT:
697 case BTF_KIND_ENUM64:
698 return true;
699 }
700
701 return false;
702 }
703
btf_int_encoding_str(u8 encoding)704 static const char *btf_int_encoding_str(u8 encoding)
705 {
706 if (encoding == 0)
707 return "(none)";
708 else if (encoding == BTF_INT_SIGNED)
709 return "SIGNED";
710 else if (encoding == BTF_INT_CHAR)
711 return "CHAR";
712 else if (encoding == BTF_INT_BOOL)
713 return "BOOL";
714 else
715 return "UNKN";
716 }
717
btf_type_int(const struct btf_type * t)718 static u32 btf_type_int(const struct btf_type *t)
719 {
720 return *(u32 *)(t + 1);
721 }
722
btf_type_array(const struct btf_type * t)723 static const struct btf_array *btf_type_array(const struct btf_type *t)
724 {
725 return (const struct btf_array *)(t + 1);
726 }
727
btf_type_enum(const struct btf_type * t)728 static const struct btf_enum *btf_type_enum(const struct btf_type *t)
729 {
730 return (const struct btf_enum *)(t + 1);
731 }
732
btf_type_var(const struct btf_type * t)733 static const struct btf_var *btf_type_var(const struct btf_type *t)
734 {
735 return (const struct btf_var *)(t + 1);
736 }
737
btf_type_decl_tag(const struct btf_type * t)738 static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t)
739 {
740 return (const struct btf_decl_tag *)(t + 1);
741 }
742
btf_type_enum64(const struct btf_type * t)743 static const struct btf_enum64 *btf_type_enum64(const struct btf_type *t)
744 {
745 return (const struct btf_enum64 *)(t + 1);
746 }
747
btf_type_ops(const struct btf_type * t)748 static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
749 {
750 return kind_ops[BTF_INFO_KIND(t->info)];
751 }
752
btf_name_offset_valid(const struct btf * btf,u32 offset)753 static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
754 {
755 if (!BTF_STR_OFFSET_VALID(offset))
756 return false;
757
758 while (offset < btf->start_str_off)
759 btf = btf->base_btf;
760
761 offset -= btf->start_str_off;
762 return offset < btf->hdr.str_len;
763 }
764
__btf_name_char_ok(char c,bool first)765 static bool __btf_name_char_ok(char c, bool first)
766 {
767 if ((first ? !isalpha(c) :
768 !isalnum(c)) &&
769 c != '_' &&
770 c != '.')
771 return false;
772 return true;
773 }
774
btf_str_by_offset(const struct btf * btf,u32 offset)775 static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
776 {
777 while (offset < btf->start_str_off)
778 btf = btf->base_btf;
779
780 offset -= btf->start_str_off;
781 if (offset < btf->hdr.str_len)
782 return &btf->strings[offset];
783
784 return NULL;
785 }
786
__btf_name_valid(const struct btf * btf,u32 offset)787 static bool __btf_name_valid(const struct btf *btf, u32 offset)
788 {
789 /* offset must be valid */
790 const char *src = btf_str_by_offset(btf, offset);
791 const char *src_limit;
792
793 if (!__btf_name_char_ok(*src, true))
794 return false;
795
796 /* set a limit on identifier length */
797 src_limit = src + KSYM_NAME_LEN;
798 src++;
799 while (*src && src < src_limit) {
800 if (!__btf_name_char_ok(*src, false))
801 return false;
802 src++;
803 }
804
805 return !*src;
806 }
807
btf_name_valid_identifier(const struct btf * btf,u32 offset)808 static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
809 {
810 return __btf_name_valid(btf, offset);
811 }
812
813 /* Allow any printable character in DATASEC names */
btf_name_valid_section(const struct btf * btf,u32 offset)814 static bool btf_name_valid_section(const struct btf *btf, u32 offset)
815 {
816 /* offset must be valid */
817 const char *src = btf_str_by_offset(btf, offset);
818 const char *src_limit;
819
820 /* set a limit on identifier length */
821 src_limit = src + KSYM_NAME_LEN;
822 src++;
823 while (*src && src < src_limit) {
824 if (!isprint(*src))
825 return false;
826 src++;
827 }
828
829 return !*src;
830 }
831
__btf_name_by_offset(const struct btf * btf,u32 offset)832 static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
833 {
834 const char *name;
835
836 if (!offset)
837 return "(anon)";
838
839 name = btf_str_by_offset(btf, offset);
840 return name ?: "(invalid-name-offset)";
841 }
842
btf_name_by_offset(const struct btf * btf,u32 offset)843 const char *btf_name_by_offset(const struct btf *btf, u32 offset)
844 {
845 return btf_str_by_offset(btf, offset);
846 }
847
btf_type_by_id(const struct btf * btf,u32 type_id)848 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
849 {
850 while (type_id < btf->start_id)
851 btf = btf->base_btf;
852
853 type_id -= btf->start_id;
854 if (type_id >= btf->nr_types)
855 return NULL;
856 return btf->types[type_id];
857 }
858 EXPORT_SYMBOL_GPL(btf_type_by_id);
859
860 /*
861 * Regular int is not a bit field and it must be either
862 * u8/u16/u32/u64 or __int128.
863 */
btf_type_int_is_regular(const struct btf_type * t)864 static bool btf_type_int_is_regular(const struct btf_type *t)
865 {
866 u8 nr_bits, nr_bytes;
867 u32 int_data;
868
869 int_data = btf_type_int(t);
870 nr_bits = BTF_INT_BITS(int_data);
871 nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
872 if (BITS_PER_BYTE_MASKED(nr_bits) ||
873 BTF_INT_OFFSET(int_data) ||
874 (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
875 nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
876 nr_bytes != (2 * sizeof(u64)))) {
877 return false;
878 }
879
880 return true;
881 }
882
883 /*
884 * Check that given struct member is a regular int with expected
885 * offset and size.
886 */
btf_member_is_reg_int(const struct btf * btf,const struct btf_type * s,const struct btf_member * m,u32 expected_offset,u32 expected_size)887 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
888 const struct btf_member *m,
889 u32 expected_offset, u32 expected_size)
890 {
891 const struct btf_type *t;
892 u32 id, int_data;
893 u8 nr_bits;
894
895 id = m->type;
896 t = btf_type_id_size(btf, &id, NULL);
897 if (!t || !btf_type_is_int(t))
898 return false;
899
900 int_data = btf_type_int(t);
901 nr_bits = BTF_INT_BITS(int_data);
902 if (btf_type_kflag(s)) {
903 u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
904 u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);
905
906 /* if kflag set, int should be a regular int and
907 * bit offset should be at byte boundary.
908 */
909 return !bitfield_size &&
910 BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
911 BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
912 }
913
914 if (BTF_INT_OFFSET(int_data) ||
915 BITS_PER_BYTE_MASKED(m->offset) ||
916 BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
917 BITS_PER_BYTE_MASKED(nr_bits) ||
918 BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
919 return false;
920
921 return true;
922 }
923
924 /* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
btf_type_skip_qualifiers(const struct btf * btf,u32 id)925 static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
926 u32 id)
927 {
928 const struct btf_type *t = btf_type_by_id(btf, id);
929
930 while (btf_type_is_modifier(t) &&
931 BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
932 t = btf_type_by_id(btf, t->type);
933 }
934
935 return t;
936 }
937
938 #define BTF_SHOW_MAX_ITER 10
939
940 #define BTF_KIND_BIT(kind) (1ULL << kind)
941
942 /*
943 * Populate show->state.name with type name information.
944 * Format of type name is
945 *
946 * [.member_name = ] (type_name)
947 */
btf_show_name(struct btf_show * show)948 static const char *btf_show_name(struct btf_show *show)
949 {
950 /* BTF_MAX_ITER array suffixes "[]" */
951 const char *array_suffixes = "[][][][][][][][][][]";
952 const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
953 /* BTF_MAX_ITER pointer suffixes "*" */
954 const char *ptr_suffixes = "**********";
955 const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
956 const char *name = NULL, *prefix = "", *parens = "";
957 const struct btf_member *m = show->state.member;
958 const struct btf_type *t;
959 const struct btf_array *array;
960 u32 id = show->state.type_id;
961 const char *member = NULL;
962 bool show_member = false;
963 u64 kinds = 0;
964 int i;
965
966 show->state.name[0] = '\0';
967
968 /*
969 * Don't show type name if we're showing an array member;
970 * in that case we show the array type so don't need to repeat
971 * ourselves for each member.
972 */
973 if (show->state.array_member)
974 return "";
975
976 /* Retrieve member name, if any. */
977 if (m) {
978 member = btf_name_by_offset(show->btf, m->name_off);
979 show_member = strlen(member) > 0;
980 id = m->type;
981 }
982
983 /*
984 * Start with type_id, as we have resolved the struct btf_type *
985 * via btf_modifier_show() past the parent typedef to the child
986 * struct, int etc it is defined as. In such cases, the type_id
987 * still represents the starting type while the struct btf_type *
988 * in our show->state points at the resolved type of the typedef.
989 */
990 t = btf_type_by_id(show->btf, id);
991 if (!t)
992 return "";
993
994 /*
995 * The goal here is to build up the right number of pointer and
996 * array suffixes while ensuring the type name for a typedef
997 * is represented. Along the way we accumulate a list of
998 * BTF kinds we have encountered, since these will inform later
999 * display; for example, pointer types will not require an
1000 * opening "{" for struct, we will just display the pointer value.
1001 *
1002 * We also want to accumulate the right number of pointer or array
1003 * indices in the format string while iterating until we get to
1004 * the typedef/pointee/array member target type.
1005 *
1006 * We start by pointing at the end of pointer and array suffix
1007 * strings; as we accumulate pointers and arrays we move the pointer
1008 * or array string backwards so it will show the expected number of
1009 * '*' or '[]' for the type. BTF_SHOW_MAX_ITER of nesting of pointers
1010 * and/or arrays and typedefs are supported as a precaution.
1011 *
1012 * We also want to get typedef name while proceeding to resolve
1013 * type it points to so that we can add parentheses if it is a
1014 * "typedef struct" etc.
1015 */
1016 for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {
1017
1018 switch (BTF_INFO_KIND(t->info)) {
1019 case BTF_KIND_TYPEDEF:
1020 if (!name)
1021 name = btf_name_by_offset(show->btf,
1022 t->name_off);
1023 kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
1024 id = t->type;
1025 break;
1026 case BTF_KIND_ARRAY:
1027 kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
1028 parens = "[";
1029 if (!t)
1030 return "";
1031 array = btf_type_array(t);
1032 if (array_suffix > array_suffixes)
1033 array_suffix -= 2;
1034 id = array->type;
1035 break;
1036 case BTF_KIND_PTR:
1037 kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
1038 if (ptr_suffix > ptr_suffixes)
1039 ptr_suffix -= 1;
1040 id = t->type;
1041 break;
1042 default:
1043 id = 0;
1044 break;
1045 }
1046 if (!id)
1047 break;
1048 t = btf_type_skip_qualifiers(show->btf, id);
1049 }
1050 /* We may not be able to represent this type; bail to be safe */
1051 if (i == BTF_SHOW_MAX_ITER)
1052 return "";
1053
1054 if (!name)
1055 name = btf_name_by_offset(show->btf, t->name_off);
1056
1057 switch (BTF_INFO_KIND(t->info)) {
1058 case BTF_KIND_STRUCT:
1059 case BTF_KIND_UNION:
1060 prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
1061 "struct" : "union";
1062 /* if it's an array of struct/union, parens is already set */
1063 if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
1064 parens = "{";
1065 break;
1066 case BTF_KIND_ENUM:
1067 case BTF_KIND_ENUM64:
1068 prefix = "enum";
1069 break;
1070 default:
1071 break;
1072 }
1073
1074 /* pointer does not require parens */
1075 if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
1076 parens = "";
1077 /* typedef does not require struct/union/enum prefix */
1078 if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
1079 prefix = "";
1080
1081 if (!name)
1082 name = "";
1083
1084 /* Even if we don't want type name info, we want parentheses etc */
1085 if (show->flags & BTF_SHOW_NONAME)
1086 snprintf(show->state.name, sizeof(show->state.name), "%s",
1087 parens);
1088 else
1089 snprintf(show->state.name, sizeof(show->state.name),
1090 "%s%s%s(%s%s%s%s%s%s)%s",
1091 /* first 3 strings comprise ".member = " */
1092 show_member ? "." : "",
1093 show_member ? member : "",
1094 show_member ? " = " : "",
1095 /* ...next is our prefix (struct, enum, etc) */
1096 prefix,
1097 strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
1098 /* ...this is the type name itself */
1099 name,
1100 /* ...suffixed by the appropriate '*', '[]' suffixes */
1101 strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
1102 array_suffix, parens);
1103
1104 return show->state.name;
1105 }
1106
__btf_show_indent(struct btf_show * show)1107 static const char *__btf_show_indent(struct btf_show *show)
1108 {
1109 const char *indents = " ";
1110 const char *indent = &indents[strlen(indents)];
1111
1112 if ((indent - show->state.depth) >= indents)
1113 return indent - show->state.depth;
1114 return indents;
1115 }
1116
btf_show_indent(struct btf_show * show)1117 static const char *btf_show_indent(struct btf_show *show)
1118 {
1119 return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
1120 }
1121
btf_show_newline(struct btf_show * show)1122 static const char *btf_show_newline(struct btf_show *show)
1123 {
1124 return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
1125 }
1126
btf_show_delim(struct btf_show * show)1127 static const char *btf_show_delim(struct btf_show *show)
1128 {
1129 if (show->state.depth == 0)
1130 return "";
1131
1132 if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
1133 BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
1134 return "|";
1135
1136 return ",";
1137 }
1138
btf_show(struct btf_show * show,const char * fmt,...)1139 __printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
1140 {
1141 va_list args;
1142
1143 if (!show->state.depth_check) {
1144 va_start(args, fmt);
1145 show->showfn(show, fmt, args);
1146 va_end(args);
1147 }
1148 }
1149
1150 /* Macros are used here as btf_show_type_value[s]() prepends and appends
1151 * format specifiers to the format specifier passed in; these do the work of
1152 * adding indentation, delimiters etc while the caller simply has to specify
1153 * the type value(s) in the format specifier + value(s).
1154 */
1155 #define btf_show_type_value(show, fmt, value) \
1156 do { \
1157 if ((value) != (__typeof__(value))0 || \
1158 (show->flags & BTF_SHOW_ZERO) || \
1159 show->state.depth == 0) { \
1160 btf_show(show, "%s%s" fmt "%s%s", \
1161 btf_show_indent(show), \
1162 btf_show_name(show), \
1163 value, btf_show_delim(show), \
1164 btf_show_newline(show)); \
1165 if (show->state.depth > show->state.depth_to_show) \
1166 show->state.depth_to_show = show->state.depth; \
1167 } \
1168 } while (0)
1169
1170 #define btf_show_type_values(show, fmt, ...) \
1171 do { \
1172 btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show), \
1173 btf_show_name(show), \
1174 __VA_ARGS__, btf_show_delim(show), \
1175 btf_show_newline(show)); \
1176 if (show->state.depth > show->state.depth_to_show) \
1177 show->state.depth_to_show = show->state.depth; \
1178 } while (0)
1179
1180 /* How much is left to copy to safe buffer after @data? */
btf_show_obj_size_left(struct btf_show * show,void * data)1181 static int btf_show_obj_size_left(struct btf_show *show, void *data)
1182 {
1183 return show->obj.head + show->obj.size - data;
1184 }
1185
1186 /* Is object pointed to by @data of @size already copied to our safe buffer? */
btf_show_obj_is_safe(struct btf_show * show,void * data,int size)1187 static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
1188 {
1189 return data >= show->obj.data &&
1190 (data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
1191 }
1192
1193 /*
1194 * If object pointed to by @data of @size falls within our safe buffer, return
1195 * the equivalent pointer to the same safe data. Assumes
1196 * copy_from_kernel_nofault() has already happened and our safe buffer is
1197 * populated.
1198 */
__btf_show_obj_safe(struct btf_show * show,void * data,int size)1199 static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
1200 {
1201 if (btf_show_obj_is_safe(show, data, size))
1202 return show->obj.safe + (data - show->obj.data);
1203 return NULL;
1204 }
1205
1206 /*
1207 * Return a safe-to-access version of data pointed to by @data.
1208 * We do this by copying the relevant amount of information
1209 * to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
1210 *
1211 * If BTF_SHOW_UNSAFE is specified, just return data as-is; no
1212 * safe copy is needed.
1213 *
1214 * Otherwise we need to determine if we have the required amount
1215 * of data (determined by the @data pointer and the size of the
1216 * largest base type we can encounter (represented by
1217 * BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
1218 * that we will be able to print some of the current object,
1219 * and if more is needed a copy will be triggered.
1220 * Some objects such as structs will not fit into the buffer;
1221 * in such cases additional copies when we iterate over their
1222 * members may be needed.
1223 *
1224 * btf_show_obj_safe() is used to return a safe buffer for
1225 * btf_show_start_type(); this ensures that as we recurse into
1226 * nested types we always have safe data for the given type.
1227 * This approach is somewhat wasteful; it's possible for example
1228 * that when iterating over a large union we'll end up copying the
1229 * same data repeatedly, but the goal is safety not performance.
1230 * We use stack data as opposed to per-CPU buffers because the
1231 * iteration over a type can take some time, and preemption handling
1232 * would greatly complicate use of the safe buffer.
1233 */
btf_show_obj_safe(struct btf_show * show,const struct btf_type * t,void * data)1234 static void *btf_show_obj_safe(struct btf_show *show,
1235 const struct btf_type *t,
1236 void *data)
1237 {
1238 const struct btf_type *rt;
1239 int size_left, size;
1240 void *safe = NULL;
1241
1242 if (show->flags & BTF_SHOW_UNSAFE)
1243 return data;
1244
1245 rt = btf_resolve_size(show->btf, t, &size);
1246 if (IS_ERR(rt)) {
1247 show->state.status = PTR_ERR(rt);
1248 return NULL;
1249 }
1250
1251 /*
1252 * Is this toplevel object? If so, set total object size and
1253 * initialize pointers. Otherwise check if we still fall within
1254 * our safe object data.
1255 */
1256 if (show->state.depth == 0) {
1257 show->obj.size = size;
1258 show->obj.head = data;
1259 } else {
1260 /*
1261 * If the size of the current object is > our remaining
1262 * safe buffer we _may_ need to do a new copy. However
1263 * consider the case of a nested struct; it's size pushes
1264 * us over the safe buffer limit, but showing any individual
1265 * struct members does not. In such cases, we don't need
1266 * to initiate a fresh copy yet; however we definitely need
1267 * at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
1268 * in our buffer, regardless of the current object size.
1269 * The logic here is that as we resolve types we will
1270 * hit a base type at some point, and we need to be sure
1271 * the next chunk of data is safely available to display
1272 * that type info safely. We cannot rely on the size of
1273 * the current object here because it may be much larger
1274 * than our current buffer (e.g. task_struct is 8k).
1275 * All we want to do here is ensure that we can print the
1276 * next basic type, which we can if either
1277 * - the current type size is within the safe buffer; or
1278 * - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
1279 * the safe buffer.
1280 */
1281 safe = __btf_show_obj_safe(show, data,
1282 min(size,
1283 BTF_SHOW_OBJ_BASE_TYPE_SIZE));
1284 }
1285
1286 /*
1287 * We need a new copy to our safe object, either because we haven't
1288 * yet copied and are initializing safe data, or because the data
1289 * we want falls outside the boundaries of the safe object.
1290 */
1291 if (!safe) {
1292 size_left = btf_show_obj_size_left(show, data);
1293 if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
1294 size_left = BTF_SHOW_OBJ_SAFE_SIZE;
1295 show->state.status = copy_from_kernel_nofault(show->obj.safe,
1296 data, size_left);
1297 if (!show->state.status) {
1298 show->obj.data = data;
1299 safe = show->obj.safe;
1300 }
1301 }
1302
1303 return safe;
1304 }
1305
1306 /*
1307 * Set the type we are starting to show and return a safe data pointer
1308 * to be used for showing the associated data.
1309 */
btf_show_start_type(struct btf_show * show,const struct btf_type * t,u32 type_id,void * data)1310 static void *btf_show_start_type(struct btf_show *show,
1311 const struct btf_type *t,
1312 u32 type_id, void *data)
1313 {
1314 show->state.type = t;
1315 show->state.type_id = type_id;
1316 show->state.name[0] = '\0';
1317
1318 return btf_show_obj_safe(show, t, data);
1319 }
1320
btf_show_end_type(struct btf_show * show)1321 static void btf_show_end_type(struct btf_show *show)
1322 {
1323 show->state.type = NULL;
1324 show->state.type_id = 0;
1325 show->state.name[0] = '\0';
1326 }
1327
btf_show_start_aggr_type(struct btf_show * show,const struct btf_type * t,u32 type_id,void * data)1328 static void *btf_show_start_aggr_type(struct btf_show *show,
1329 const struct btf_type *t,
1330 u32 type_id, void *data)
1331 {
1332 void *safe_data = btf_show_start_type(show, t, type_id, data);
1333
1334 if (!safe_data)
1335 return safe_data;
1336
1337 btf_show(show, "%s%s%s", btf_show_indent(show),
1338 btf_show_name(show),
1339 btf_show_newline(show));
1340 show->state.depth++;
1341 return safe_data;
1342 }
1343
btf_show_end_aggr_type(struct btf_show * show,const char * suffix)1344 static void btf_show_end_aggr_type(struct btf_show *show,
1345 const char *suffix)
1346 {
1347 show->state.depth--;
1348 btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
1349 btf_show_delim(show), btf_show_newline(show));
1350 btf_show_end_type(show);
1351 }
1352
btf_show_start_member(struct btf_show * show,const struct btf_member * m)1353 static void btf_show_start_member(struct btf_show *show,
1354 const struct btf_member *m)
1355 {
1356 show->state.member = m;
1357 }
1358
btf_show_start_array_member(struct btf_show * show)1359 static void btf_show_start_array_member(struct btf_show *show)
1360 {
1361 show->state.array_member = 1;
1362 btf_show_start_member(show, NULL);
1363 }
1364
btf_show_end_member(struct btf_show * show)1365 static void btf_show_end_member(struct btf_show *show)
1366 {
1367 show->state.member = NULL;
1368 }
1369
btf_show_end_array_member(struct btf_show * show)1370 static void btf_show_end_array_member(struct btf_show *show)
1371 {
1372 show->state.array_member = 0;
1373 btf_show_end_member(show);
1374 }
1375
btf_show_start_array_type(struct btf_show * show,const struct btf_type * t,u32 type_id,u16 array_encoding,void * data)1376 static void *btf_show_start_array_type(struct btf_show *show,
1377 const struct btf_type *t,
1378 u32 type_id,
1379 u16 array_encoding,
1380 void *data)
1381 {
1382 show->state.array_encoding = array_encoding;
1383 show->state.array_terminated = 0;
1384 return btf_show_start_aggr_type(show, t, type_id, data);
1385 }
1386
btf_show_end_array_type(struct btf_show * show)1387 static void btf_show_end_array_type(struct btf_show *show)
1388 {
1389 show->state.array_encoding = 0;
1390 show->state.array_terminated = 0;
1391 btf_show_end_aggr_type(show, "]");
1392 }
1393
btf_show_start_struct_type(struct btf_show * show,const struct btf_type * t,u32 type_id,void * data)1394 static void *btf_show_start_struct_type(struct btf_show *show,
1395 const struct btf_type *t,
1396 u32 type_id,
1397 void *data)
1398 {
1399 return btf_show_start_aggr_type(show, t, type_id, data);
1400 }
1401
btf_show_end_struct_type(struct btf_show * show)1402 static void btf_show_end_struct_type(struct btf_show *show)
1403 {
1404 btf_show_end_aggr_type(show, "}");
1405 }
1406
__btf_verifier_log(struct bpf_verifier_log * log,const char * fmt,...)1407 __printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
1408 const char *fmt, ...)
1409 {
1410 va_list args;
1411
1412 va_start(args, fmt);
1413 bpf_verifier_vlog(log, fmt, args);
1414 va_end(args);
1415 }
1416
btf_verifier_log(struct btf_verifier_env * env,const char * fmt,...)1417 __printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
1418 const char *fmt, ...)
1419 {
1420 struct bpf_verifier_log *log = &env->log;
1421 va_list args;
1422
1423 if (!bpf_verifier_log_needed(log))
1424 return;
1425
1426 va_start(args, fmt);
1427 bpf_verifier_vlog(log, fmt, args);
1428 va_end(args);
1429 }
1430
__btf_verifier_log_type(struct btf_verifier_env * env,const struct btf_type * t,bool log_details,const char * fmt,...)1431 __printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
1432 const struct btf_type *t,
1433 bool log_details,
1434 const char *fmt, ...)
1435 {
1436 struct bpf_verifier_log *log = &env->log;
1437 struct btf *btf = env->btf;
1438 va_list args;
1439
1440 if (!bpf_verifier_log_needed(log))
1441 return;
1442
1443 if (log->level == BPF_LOG_KERNEL) {
1444 /* btf verifier prints all types it is processing via
1445 * btf_verifier_log_type(..., fmt = NULL).
1446 * Skip those prints for in-kernel BTF verification.
1447 */
1448 if (!fmt)
1449 return;
1450
1451 /* Skip logging when loading module BTF with mismatches permitted */
1452 if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
1453 return;
1454 }
1455
1456 __btf_verifier_log(log, "[%u] %s %s%s",
1457 env->log_type_id,
1458 btf_type_str(t),
1459 __btf_name_by_offset(btf, t->name_off),
1460 log_details ? " " : "");
1461
1462 if (log_details)
1463 btf_type_ops(t)->log_details(env, t);
1464
1465 if (fmt && *fmt) {
1466 __btf_verifier_log(log, " ");
1467 va_start(args, fmt);
1468 bpf_verifier_vlog(log, fmt, args);
1469 va_end(args);
1470 }
1471
1472 __btf_verifier_log(log, "\n");
1473 }
1474
1475 #define btf_verifier_log_type(env, t, ...) \
1476 __btf_verifier_log_type((env), (t), true, __VA_ARGS__)
1477 #define btf_verifier_log_basic(env, t, ...) \
1478 __btf_verifier_log_type((env), (t), false, __VA_ARGS__)
1479
1480 __printf(4, 5)
btf_verifier_log_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const char * fmt,...)1481 static void btf_verifier_log_member(struct btf_verifier_env *env,
1482 const struct btf_type *struct_type,
1483 const struct btf_member *member,
1484 const char *fmt, ...)
1485 {
1486 struct bpf_verifier_log *log = &env->log;
1487 struct btf *btf = env->btf;
1488 va_list args;
1489
1490 if (!bpf_verifier_log_needed(log))
1491 return;
1492
1493 if (log->level == BPF_LOG_KERNEL) {
1494 if (!fmt)
1495 return;
1496
1497 /* Skip logging when loading module BTF with mismatches permitted */
1498 if (env->btf->base_btf && IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
1499 return;
1500 }
1501
1502 /* The CHECK_META phase already did a btf dump.
1503 *
1504 * If member is logged again, it must hit an error in
1505 * parsing this member. It is useful to print out which
1506 * struct this member belongs to.
1507 */
1508 if (env->phase != CHECK_META)
1509 btf_verifier_log_type(env, struct_type, NULL);
1510
1511 if (btf_type_kflag(struct_type))
1512 __btf_verifier_log(log,
1513 "\t%s type_id=%u bitfield_size=%u bits_offset=%u",
1514 __btf_name_by_offset(btf, member->name_off),
1515 member->type,
1516 BTF_MEMBER_BITFIELD_SIZE(member->offset),
1517 BTF_MEMBER_BIT_OFFSET(member->offset));
1518 else
1519 __btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
1520 __btf_name_by_offset(btf, member->name_off),
1521 member->type, member->offset);
1522
1523 if (fmt && *fmt) {
1524 __btf_verifier_log(log, " ");
1525 va_start(args, fmt);
1526 bpf_verifier_vlog(log, fmt, args);
1527 va_end(args);
1528 }
1529
1530 __btf_verifier_log(log, "\n");
1531 }
1532
1533 __printf(4, 5)
btf_verifier_log_vsi(struct btf_verifier_env * env,const struct btf_type * datasec_type,const struct btf_var_secinfo * vsi,const char * fmt,...)1534 static void btf_verifier_log_vsi(struct btf_verifier_env *env,
1535 const struct btf_type *datasec_type,
1536 const struct btf_var_secinfo *vsi,
1537 const char *fmt, ...)
1538 {
1539 struct bpf_verifier_log *log = &env->log;
1540 va_list args;
1541
1542 if (!bpf_verifier_log_needed(log))
1543 return;
1544 if (log->level == BPF_LOG_KERNEL && !fmt)
1545 return;
1546 if (env->phase != CHECK_META)
1547 btf_verifier_log_type(env, datasec_type, NULL);
1548
1549 __btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
1550 vsi->type, vsi->offset, vsi->size);
1551 if (fmt && *fmt) {
1552 __btf_verifier_log(log, " ");
1553 va_start(args, fmt);
1554 bpf_verifier_vlog(log, fmt, args);
1555 va_end(args);
1556 }
1557
1558 __btf_verifier_log(log, "\n");
1559 }
1560
btf_verifier_log_hdr(struct btf_verifier_env * env,u32 btf_data_size)1561 static void btf_verifier_log_hdr(struct btf_verifier_env *env,
1562 u32 btf_data_size)
1563 {
1564 struct bpf_verifier_log *log = &env->log;
1565 const struct btf *btf = env->btf;
1566 const struct btf_header *hdr;
1567
1568 if (!bpf_verifier_log_needed(log))
1569 return;
1570
1571 if (log->level == BPF_LOG_KERNEL)
1572 return;
1573 hdr = &btf->hdr;
1574 __btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
1575 __btf_verifier_log(log, "version: %u\n", hdr->version);
1576 __btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
1577 __btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
1578 __btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
1579 __btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
1580 __btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
1581 __btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
1582 __btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
1583 }
1584
btf_add_type(struct btf_verifier_env * env,struct btf_type * t)1585 static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
1586 {
1587 struct btf *btf = env->btf;
1588
1589 if (btf->types_size == btf->nr_types) {
1590 /* Expand 'types' array */
1591
1592 struct btf_type **new_types;
1593 u32 expand_by, new_size;
1594
1595 if (btf->start_id + btf->types_size == BTF_MAX_TYPE) {
1596 btf_verifier_log(env, "Exceeded max num of types");
1597 return -E2BIG;
1598 }
1599
1600 expand_by = max_t(u32, btf->types_size >> 2, 16);
1601 new_size = min_t(u32, BTF_MAX_TYPE,
1602 btf->types_size + expand_by);
1603
1604 new_types = kvcalloc(new_size, sizeof(*new_types),
1605 GFP_KERNEL | __GFP_NOWARN);
1606 if (!new_types)
1607 return -ENOMEM;
1608
1609 if (btf->nr_types == 0) {
1610 if (!btf->base_btf) {
1611 /* lazily init VOID type */
1612 new_types[0] = &btf_void;
1613 btf->nr_types++;
1614 }
1615 } else {
1616 memcpy(new_types, btf->types,
1617 sizeof(*btf->types) * btf->nr_types);
1618 }
1619
1620 kvfree(btf->types);
1621 btf->types = new_types;
1622 btf->types_size = new_size;
1623 }
1624
1625 btf->types[btf->nr_types++] = t;
1626
1627 return 0;
1628 }
1629
btf_alloc_id(struct btf * btf)1630 static int btf_alloc_id(struct btf *btf)
1631 {
1632 int id;
1633
1634 idr_preload(GFP_KERNEL);
1635 spin_lock_bh(&btf_idr_lock);
1636 id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
1637 if (id > 0)
1638 btf->id = id;
1639 spin_unlock_bh(&btf_idr_lock);
1640 idr_preload_end();
1641
1642 if (WARN_ON_ONCE(!id))
1643 return -ENOSPC;
1644
1645 return id > 0 ? 0 : id;
1646 }
1647
btf_free_id(struct btf * btf)1648 static void btf_free_id(struct btf *btf)
1649 {
1650 unsigned long flags;
1651
1652 /*
1653 * In map-in-map, calling map_delete_elem() on outer
1654 * map will call bpf_map_put on the inner map.
1655 * It will then eventually call btf_free_id()
1656 * on the inner map. Some of the map_delete_elem()
1657 * implementation may have irq disabled, so
1658 * we need to use the _irqsave() version instead
1659 * of the _bh() version.
1660 */
1661 spin_lock_irqsave(&btf_idr_lock, flags);
1662 idr_remove(&btf_idr, btf->id);
1663 spin_unlock_irqrestore(&btf_idr_lock, flags);
1664 }
1665
btf_free_kfunc_set_tab(struct btf * btf)1666 static void btf_free_kfunc_set_tab(struct btf *btf)
1667 {
1668 struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
1669 int hook;
1670
1671 if (!tab)
1672 return;
1673 /* For module BTF, we directly assign the sets being registered, so
1674 * there is nothing to free except kfunc_set_tab.
1675 */
1676 if (btf_is_module(btf))
1677 goto free_tab;
1678 for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++)
1679 kfree(tab->sets[hook]);
1680 free_tab:
1681 kfree(tab);
1682 btf->kfunc_set_tab = NULL;
1683 }
1684
btf_free_dtor_kfunc_tab(struct btf * btf)1685 static void btf_free_dtor_kfunc_tab(struct btf *btf)
1686 {
1687 struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
1688
1689 if (!tab)
1690 return;
1691 kfree(tab);
1692 btf->dtor_kfunc_tab = NULL;
1693 }
1694
btf_struct_metas_free(struct btf_struct_metas * tab)1695 static void btf_struct_metas_free(struct btf_struct_metas *tab)
1696 {
1697 int i;
1698
1699 if (!tab)
1700 return;
1701 for (i = 0; i < tab->cnt; i++)
1702 btf_record_free(tab->types[i].record);
1703 kfree(tab);
1704 }
1705
btf_free_struct_meta_tab(struct btf * btf)1706 static void btf_free_struct_meta_tab(struct btf *btf)
1707 {
1708 struct btf_struct_metas *tab = btf->struct_meta_tab;
1709
1710 btf_struct_metas_free(tab);
1711 btf->struct_meta_tab = NULL;
1712 }
1713
btf_free_struct_ops_tab(struct btf * btf)1714 static void btf_free_struct_ops_tab(struct btf *btf)
1715 {
1716 struct btf_struct_ops_tab *tab = btf->struct_ops_tab;
1717 u32 i;
1718
1719 if (!tab)
1720 return;
1721
1722 for (i = 0; i < tab->cnt; i++)
1723 bpf_struct_ops_desc_release(&tab->ops[i]);
1724
1725 kfree(tab);
1726 btf->struct_ops_tab = NULL;
1727 }
1728
btf_free(struct btf * btf)1729 static void btf_free(struct btf *btf)
1730 {
1731 btf_free_struct_meta_tab(btf);
1732 btf_free_dtor_kfunc_tab(btf);
1733 btf_free_kfunc_set_tab(btf);
1734 btf_free_struct_ops_tab(btf);
1735 kvfree(btf->types);
1736 kvfree(btf->resolved_sizes);
1737 kvfree(btf->resolved_ids);
1738 kvfree(btf->data);
1739 kfree(btf);
1740 }
1741
btf_free_rcu(struct rcu_head * rcu)1742 static void btf_free_rcu(struct rcu_head *rcu)
1743 {
1744 struct btf *btf = container_of(rcu, struct btf, rcu);
1745
1746 btf_free(btf);
1747 }
1748
btf_get_name(const struct btf * btf)1749 const char *btf_get_name(const struct btf *btf)
1750 {
1751 return btf->name;
1752 }
1753
btf_get(struct btf * btf)1754 void btf_get(struct btf *btf)
1755 {
1756 refcount_inc(&btf->refcnt);
1757 }
1758
btf_put(struct btf * btf)1759 void btf_put(struct btf *btf)
1760 {
1761 if (btf && refcount_dec_and_test(&btf->refcnt)) {
1762 btf_free_id(btf);
1763 call_rcu(&btf->rcu, btf_free_rcu);
1764 }
1765 }
1766
env_resolve_init(struct btf_verifier_env * env)1767 static int env_resolve_init(struct btf_verifier_env *env)
1768 {
1769 struct btf *btf = env->btf;
1770 u32 nr_types = btf->nr_types;
1771 u32 *resolved_sizes = NULL;
1772 u32 *resolved_ids = NULL;
1773 u8 *visit_states = NULL;
1774
1775 resolved_sizes = kvcalloc(nr_types, sizeof(*resolved_sizes),
1776 GFP_KERNEL | __GFP_NOWARN);
1777 if (!resolved_sizes)
1778 goto nomem;
1779
1780 resolved_ids = kvcalloc(nr_types, sizeof(*resolved_ids),
1781 GFP_KERNEL | __GFP_NOWARN);
1782 if (!resolved_ids)
1783 goto nomem;
1784
1785 visit_states = kvcalloc(nr_types, sizeof(*visit_states),
1786 GFP_KERNEL | __GFP_NOWARN);
1787 if (!visit_states)
1788 goto nomem;
1789
1790 btf->resolved_sizes = resolved_sizes;
1791 btf->resolved_ids = resolved_ids;
1792 env->visit_states = visit_states;
1793
1794 return 0;
1795
1796 nomem:
1797 kvfree(resolved_sizes);
1798 kvfree(resolved_ids);
1799 kvfree(visit_states);
1800 return -ENOMEM;
1801 }
1802
btf_verifier_env_free(struct btf_verifier_env * env)1803 static void btf_verifier_env_free(struct btf_verifier_env *env)
1804 {
1805 kvfree(env->visit_states);
1806 kfree(env);
1807 }
1808
env_type_is_resolve_sink(const struct btf_verifier_env * env,const struct btf_type * next_type)1809 static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
1810 const struct btf_type *next_type)
1811 {
1812 switch (env->resolve_mode) {
1813 case RESOLVE_TBD:
1814 /* int, enum or void is a sink */
1815 return !btf_type_needs_resolve(next_type);
1816 case RESOLVE_PTR:
1817 /* int, enum, void, struct, array, func or func_proto is a sink
1818 * for ptr
1819 */
1820 return !btf_type_is_modifier(next_type) &&
1821 !btf_type_is_ptr(next_type);
1822 case RESOLVE_STRUCT_OR_ARRAY:
1823 /* int, enum, void, ptr, func or func_proto is a sink
1824 * for struct and array
1825 */
1826 return !btf_type_is_modifier(next_type) &&
1827 !btf_type_is_array(next_type) &&
1828 !btf_type_is_struct(next_type);
1829 default:
1830 BUG();
1831 }
1832 }
1833
env_type_is_resolved(const struct btf_verifier_env * env,u32 type_id)1834 static bool env_type_is_resolved(const struct btf_verifier_env *env,
1835 u32 type_id)
1836 {
1837 /* base BTF types should be resolved by now */
1838 if (type_id < env->btf->start_id)
1839 return true;
1840
1841 return env->visit_states[type_id - env->btf->start_id] == RESOLVED;
1842 }
1843
env_stack_push(struct btf_verifier_env * env,const struct btf_type * t,u32 type_id)1844 static int env_stack_push(struct btf_verifier_env *env,
1845 const struct btf_type *t, u32 type_id)
1846 {
1847 const struct btf *btf = env->btf;
1848 struct resolve_vertex *v;
1849
1850 if (env->top_stack == MAX_RESOLVE_DEPTH)
1851 return -E2BIG;
1852
1853 if (type_id < btf->start_id
1854 || env->visit_states[type_id - btf->start_id] != NOT_VISITED)
1855 return -EEXIST;
1856
1857 env->visit_states[type_id - btf->start_id] = VISITED;
1858
1859 v = &env->stack[env->top_stack++];
1860 v->t = t;
1861 v->type_id = type_id;
1862 v->next_member = 0;
1863
1864 if (env->resolve_mode == RESOLVE_TBD) {
1865 if (btf_type_is_ptr(t))
1866 env->resolve_mode = RESOLVE_PTR;
1867 else if (btf_type_is_struct(t) || btf_type_is_array(t))
1868 env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
1869 }
1870
1871 return 0;
1872 }
1873
env_stack_set_next_member(struct btf_verifier_env * env,u16 next_member)1874 static void env_stack_set_next_member(struct btf_verifier_env *env,
1875 u16 next_member)
1876 {
1877 env->stack[env->top_stack - 1].next_member = next_member;
1878 }
1879
env_stack_pop_resolved(struct btf_verifier_env * env,u32 resolved_type_id,u32 resolved_size)1880 static void env_stack_pop_resolved(struct btf_verifier_env *env,
1881 u32 resolved_type_id,
1882 u32 resolved_size)
1883 {
1884 u32 type_id = env->stack[--(env->top_stack)].type_id;
1885 struct btf *btf = env->btf;
1886
1887 type_id -= btf->start_id; /* adjust to local type id */
1888 btf->resolved_sizes[type_id] = resolved_size;
1889 btf->resolved_ids[type_id] = resolved_type_id;
1890 env->visit_states[type_id] = RESOLVED;
1891 }
1892
env_stack_peak(struct btf_verifier_env * env)1893 static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
1894 {
1895 return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
1896 }
1897
1898 /* Resolve the size of a passed-in "type"
1899 *
1900 * type: is an array (e.g. u32 array[x][y])
1901 * return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
1902 * *type_size: (x * y * sizeof(u32)). Hence, *type_size always
1903 * corresponds to the return type.
1904 * *elem_type: u32
1905 * *elem_id: id of u32
1906 * *total_nelems: (x * y). Hence, individual elem size is
1907 * (*type_size / *total_nelems)
1908 * *type_id: id of type if it's changed within the function, 0 if not
1909 *
1910 * type: is not an array (e.g. const struct X)
1911 * return type: type "struct X"
1912 * *type_size: sizeof(struct X)
1913 * *elem_type: same as return type ("struct X")
1914 * *elem_id: 0
1915 * *total_nelems: 1
1916 * *type_id: id of type if it's changed within the function, 0 if not
1917 */
1918 static const struct btf_type *
__btf_resolve_size(const struct btf * btf,const struct btf_type * type,u32 * type_size,const struct btf_type ** elem_type,u32 * elem_id,u32 * total_nelems,u32 * type_id)1919 __btf_resolve_size(const struct btf *btf, const struct btf_type *type,
1920 u32 *type_size, const struct btf_type **elem_type,
1921 u32 *elem_id, u32 *total_nelems, u32 *type_id)
1922 {
1923 const struct btf_type *array_type = NULL;
1924 const struct btf_array *array = NULL;
1925 u32 i, size, nelems = 1, id = 0;
1926
1927 for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
1928 switch (BTF_INFO_KIND(type->info)) {
1929 /* type->size can be used */
1930 case BTF_KIND_INT:
1931 case BTF_KIND_STRUCT:
1932 case BTF_KIND_UNION:
1933 case BTF_KIND_ENUM:
1934 case BTF_KIND_FLOAT:
1935 case BTF_KIND_ENUM64:
1936 size = type->size;
1937 goto resolved;
1938
1939 case BTF_KIND_PTR:
1940 size = sizeof(void *);
1941 goto resolved;
1942
1943 /* Modifiers */
1944 case BTF_KIND_TYPEDEF:
1945 case BTF_KIND_VOLATILE:
1946 case BTF_KIND_CONST:
1947 case BTF_KIND_RESTRICT:
1948 case BTF_KIND_TYPE_TAG:
1949 id = type->type;
1950 type = btf_type_by_id(btf, type->type);
1951 break;
1952
1953 case BTF_KIND_ARRAY:
1954 if (!array_type)
1955 array_type = type;
1956 array = btf_type_array(type);
1957 if (nelems && array->nelems > U32_MAX / nelems)
1958 return ERR_PTR(-EINVAL);
1959 nelems *= array->nelems;
1960 type = btf_type_by_id(btf, array->type);
1961 break;
1962
1963 /* type without size */
1964 default:
1965 return ERR_PTR(-EINVAL);
1966 }
1967 }
1968
1969 return ERR_PTR(-EINVAL);
1970
1971 resolved:
1972 if (nelems && size > U32_MAX / nelems)
1973 return ERR_PTR(-EINVAL);
1974
1975 *type_size = nelems * size;
1976 if (total_nelems)
1977 *total_nelems = nelems;
1978 if (elem_type)
1979 *elem_type = type;
1980 if (elem_id)
1981 *elem_id = array ? array->type : 0;
1982 if (type_id && id)
1983 *type_id = id;
1984
1985 return array_type ? : type;
1986 }
1987
1988 const struct btf_type *
btf_resolve_size(const struct btf * btf,const struct btf_type * type,u32 * type_size)1989 btf_resolve_size(const struct btf *btf, const struct btf_type *type,
1990 u32 *type_size)
1991 {
1992 return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
1993 }
1994
btf_resolved_type_id(const struct btf * btf,u32 type_id)1995 static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
1996 {
1997 while (type_id < btf->start_id)
1998 btf = btf->base_btf;
1999
2000 return btf->resolved_ids[type_id - btf->start_id];
2001 }
2002
2003 /* The input param "type_id" must point to a needs_resolve type */
btf_type_id_resolve(const struct btf * btf,u32 * type_id)2004 static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
2005 u32 *type_id)
2006 {
2007 *type_id = btf_resolved_type_id(btf, *type_id);
2008 return btf_type_by_id(btf, *type_id);
2009 }
2010
btf_resolved_type_size(const struct btf * btf,u32 type_id)2011 static u32 btf_resolved_type_size(const struct btf *btf, u32 type_id)
2012 {
2013 while (type_id < btf->start_id)
2014 btf = btf->base_btf;
2015
2016 return btf->resolved_sizes[type_id - btf->start_id];
2017 }
2018
btf_type_id_size(const struct btf * btf,u32 * type_id,u32 * ret_size)2019 const struct btf_type *btf_type_id_size(const struct btf *btf,
2020 u32 *type_id, u32 *ret_size)
2021 {
2022 const struct btf_type *size_type;
2023 u32 size_type_id = *type_id;
2024 u32 size = 0;
2025
2026 size_type = btf_type_by_id(btf, size_type_id);
2027 if (btf_type_nosize_or_null(size_type))
2028 return NULL;
2029
2030 if (btf_type_has_size(size_type)) {
2031 size = size_type->size;
2032 } else if (btf_type_is_array(size_type)) {
2033 size = btf_resolved_type_size(btf, size_type_id);
2034 } else if (btf_type_is_ptr(size_type)) {
2035 size = sizeof(void *);
2036 } else {
2037 if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
2038 !btf_type_is_var(size_type)))
2039 return NULL;
2040
2041 size_type_id = btf_resolved_type_id(btf, size_type_id);
2042 size_type = btf_type_by_id(btf, size_type_id);
2043 if (btf_type_nosize_or_null(size_type))
2044 return NULL;
2045 else if (btf_type_has_size(size_type))
2046 size = size_type->size;
2047 else if (btf_type_is_array(size_type))
2048 size = btf_resolved_type_size(btf, size_type_id);
2049 else if (btf_type_is_ptr(size_type))
2050 size = sizeof(void *);
2051 else
2052 return NULL;
2053 }
2054
2055 *type_id = size_type_id;
2056 if (ret_size)
2057 *ret_size = size;
2058
2059 return size_type;
2060 }
2061
btf_df_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2062 static int btf_df_check_member(struct btf_verifier_env *env,
2063 const struct btf_type *struct_type,
2064 const struct btf_member *member,
2065 const struct btf_type *member_type)
2066 {
2067 btf_verifier_log_basic(env, struct_type,
2068 "Unsupported check_member");
2069 return -EINVAL;
2070 }
2071
btf_df_check_kflag_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2072 static int btf_df_check_kflag_member(struct btf_verifier_env *env,
2073 const struct btf_type *struct_type,
2074 const struct btf_member *member,
2075 const struct btf_type *member_type)
2076 {
2077 btf_verifier_log_basic(env, struct_type,
2078 "Unsupported check_kflag_member");
2079 return -EINVAL;
2080 }
2081
2082 /* Used for ptr, array struct/union and float type members.
2083 * int, enum and modifier types have their specific callback functions.
2084 */
btf_generic_check_kflag_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2085 static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
2086 const struct btf_type *struct_type,
2087 const struct btf_member *member,
2088 const struct btf_type *member_type)
2089 {
2090 if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
2091 btf_verifier_log_member(env, struct_type, member,
2092 "Invalid member bitfield_size");
2093 return -EINVAL;
2094 }
2095
2096 /* bitfield size is 0, so member->offset represents bit offset only.
2097 * It is safe to call non kflag check_member variants.
2098 */
2099 return btf_type_ops(member_type)->check_member(env, struct_type,
2100 member,
2101 member_type);
2102 }
2103
btf_df_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)2104 static int btf_df_resolve(struct btf_verifier_env *env,
2105 const struct resolve_vertex *v)
2106 {
2107 btf_verifier_log_basic(env, v->t, "Unsupported resolve");
2108 return -EINVAL;
2109 }
2110
btf_df_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offsets,struct btf_show * show)2111 static void btf_df_show(const struct btf *btf, const struct btf_type *t,
2112 u32 type_id, void *data, u8 bits_offsets,
2113 struct btf_show *show)
2114 {
2115 btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
2116 }
2117
btf_int_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2118 static int btf_int_check_member(struct btf_verifier_env *env,
2119 const struct btf_type *struct_type,
2120 const struct btf_member *member,
2121 const struct btf_type *member_type)
2122 {
2123 u32 int_data = btf_type_int(member_type);
2124 u32 struct_bits_off = member->offset;
2125 u32 struct_size = struct_type->size;
2126 u32 nr_copy_bits;
2127 u32 bytes_offset;
2128
2129 if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
2130 btf_verifier_log_member(env, struct_type, member,
2131 "bits_offset exceeds U32_MAX");
2132 return -EINVAL;
2133 }
2134
2135 struct_bits_off += BTF_INT_OFFSET(int_data);
2136 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
2137 nr_copy_bits = BTF_INT_BITS(int_data) +
2138 BITS_PER_BYTE_MASKED(struct_bits_off);
2139
2140 if (nr_copy_bits > BITS_PER_U128) {
2141 btf_verifier_log_member(env, struct_type, member,
2142 "nr_copy_bits exceeds 128");
2143 return -EINVAL;
2144 }
2145
2146 if (struct_size < bytes_offset ||
2147 struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
2148 btf_verifier_log_member(env, struct_type, member,
2149 "Member exceeds struct_size");
2150 return -EINVAL;
2151 }
2152
2153 return 0;
2154 }
2155
btf_int_check_kflag_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2156 static int btf_int_check_kflag_member(struct btf_verifier_env *env,
2157 const struct btf_type *struct_type,
2158 const struct btf_member *member,
2159 const struct btf_type *member_type)
2160 {
2161 u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
2162 u32 int_data = btf_type_int(member_type);
2163 u32 struct_size = struct_type->size;
2164 u32 nr_copy_bits;
2165
2166 /* a regular int type is required for the kflag int member */
2167 if (!btf_type_int_is_regular(member_type)) {
2168 btf_verifier_log_member(env, struct_type, member,
2169 "Invalid member base type");
2170 return -EINVAL;
2171 }
2172
2173 /* check sanity of bitfield size */
2174 nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
2175 struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
2176 nr_int_data_bits = BTF_INT_BITS(int_data);
2177 if (!nr_bits) {
2178 /* Not a bitfield member, member offset must be at byte
2179 * boundary.
2180 */
2181 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
2182 btf_verifier_log_member(env, struct_type, member,
2183 "Invalid member offset");
2184 return -EINVAL;
2185 }
2186
2187 nr_bits = nr_int_data_bits;
2188 } else if (nr_bits > nr_int_data_bits) {
2189 btf_verifier_log_member(env, struct_type, member,
2190 "Invalid member bitfield_size");
2191 return -EINVAL;
2192 }
2193
2194 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
2195 nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
2196 if (nr_copy_bits > BITS_PER_U128) {
2197 btf_verifier_log_member(env, struct_type, member,
2198 "nr_copy_bits exceeds 128");
2199 return -EINVAL;
2200 }
2201
2202 if (struct_size < bytes_offset ||
2203 struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
2204 btf_verifier_log_member(env, struct_type, member,
2205 "Member exceeds struct_size");
2206 return -EINVAL;
2207 }
2208
2209 return 0;
2210 }
2211
btf_int_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)2212 static s32 btf_int_check_meta(struct btf_verifier_env *env,
2213 const struct btf_type *t,
2214 u32 meta_left)
2215 {
2216 u32 int_data, nr_bits, meta_needed = sizeof(int_data);
2217 u16 encoding;
2218
2219 if (meta_left < meta_needed) {
2220 btf_verifier_log_basic(env, t,
2221 "meta_left:%u meta_needed:%u",
2222 meta_left, meta_needed);
2223 return -EINVAL;
2224 }
2225
2226 if (btf_type_vlen(t)) {
2227 btf_verifier_log_type(env, t, "vlen != 0");
2228 return -EINVAL;
2229 }
2230
2231 if (btf_type_kflag(t)) {
2232 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
2233 return -EINVAL;
2234 }
2235
2236 int_data = btf_type_int(t);
2237 if (int_data & ~BTF_INT_MASK) {
2238 btf_verifier_log_basic(env, t, "Invalid int_data:%x",
2239 int_data);
2240 return -EINVAL;
2241 }
2242
2243 nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
2244
2245 if (nr_bits > BITS_PER_U128) {
2246 btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
2247 BITS_PER_U128);
2248 return -EINVAL;
2249 }
2250
2251 if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
2252 btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
2253 return -EINVAL;
2254 }
2255
2256 /*
2257 * Only one of the encoding bits is allowed and it
2258 * should be sufficient for the pretty print purpose (i.e. decoding).
2259 * Multiple bits can be allowed later if it is found
2260 * to be insufficient.
2261 */
2262 encoding = BTF_INT_ENCODING(int_data);
2263 if (encoding &&
2264 encoding != BTF_INT_SIGNED &&
2265 encoding != BTF_INT_CHAR &&
2266 encoding != BTF_INT_BOOL) {
2267 btf_verifier_log_type(env, t, "Unsupported encoding");
2268 return -ENOTSUPP;
2269 }
2270
2271 btf_verifier_log_type(env, t, NULL);
2272
2273 return meta_needed;
2274 }
2275
btf_int_log(struct btf_verifier_env * env,const struct btf_type * t)2276 static void btf_int_log(struct btf_verifier_env *env,
2277 const struct btf_type *t)
2278 {
2279 int int_data = btf_type_int(t);
2280
2281 btf_verifier_log(env,
2282 "size=%u bits_offset=%u nr_bits=%u encoding=%s",
2283 t->size, BTF_INT_OFFSET(int_data),
2284 BTF_INT_BITS(int_data),
2285 btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
2286 }
2287
btf_int128_print(struct btf_show * show,void * data)2288 static void btf_int128_print(struct btf_show *show, void *data)
2289 {
2290 /* data points to a __int128 number.
2291 * Suppose
2292 * int128_num = *(__int128 *)data;
2293 * The below formulas shows what upper_num and lower_num represents:
2294 * upper_num = int128_num >> 64;
2295 * lower_num = int128_num & 0xffffffffFFFFFFFFULL;
2296 */
2297 u64 upper_num, lower_num;
2298
2299 #ifdef __BIG_ENDIAN_BITFIELD
2300 upper_num = *(u64 *)data;
2301 lower_num = *(u64 *)(data + 8);
2302 #else
2303 upper_num = *(u64 *)(data + 8);
2304 lower_num = *(u64 *)data;
2305 #endif
2306 if (upper_num == 0)
2307 btf_show_type_value(show, "0x%llx", lower_num);
2308 else
2309 btf_show_type_values(show, "0x%llx%016llx", upper_num,
2310 lower_num);
2311 }
2312
btf_int128_shift(u64 * print_num,u16 left_shift_bits,u16 right_shift_bits)2313 static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
2314 u16 right_shift_bits)
2315 {
2316 u64 upper_num, lower_num;
2317
2318 #ifdef __BIG_ENDIAN_BITFIELD
2319 upper_num = print_num[0];
2320 lower_num = print_num[1];
2321 #else
2322 upper_num = print_num[1];
2323 lower_num = print_num[0];
2324 #endif
2325
2326 /* shake out un-needed bits by shift/or operations */
2327 if (left_shift_bits >= 64) {
2328 upper_num = lower_num << (left_shift_bits - 64);
2329 lower_num = 0;
2330 } else {
2331 upper_num = (upper_num << left_shift_bits) |
2332 (lower_num >> (64 - left_shift_bits));
2333 lower_num = lower_num << left_shift_bits;
2334 }
2335
2336 if (right_shift_bits >= 64) {
2337 lower_num = upper_num >> (right_shift_bits - 64);
2338 upper_num = 0;
2339 } else {
2340 lower_num = (lower_num >> right_shift_bits) |
2341 (upper_num << (64 - right_shift_bits));
2342 upper_num = upper_num >> right_shift_bits;
2343 }
2344
2345 #ifdef __BIG_ENDIAN_BITFIELD
2346 print_num[0] = upper_num;
2347 print_num[1] = lower_num;
2348 #else
2349 print_num[0] = lower_num;
2350 print_num[1] = upper_num;
2351 #endif
2352 }
2353
btf_bitfield_show(void * data,u8 bits_offset,u8 nr_bits,struct btf_show * show)2354 static void btf_bitfield_show(void *data, u8 bits_offset,
2355 u8 nr_bits, struct btf_show *show)
2356 {
2357 u16 left_shift_bits, right_shift_bits;
2358 u8 nr_copy_bytes;
2359 u8 nr_copy_bits;
2360 u64 print_num[2] = {};
2361
2362 nr_copy_bits = nr_bits + bits_offset;
2363 nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);
2364
2365 memcpy(print_num, data, nr_copy_bytes);
2366
2367 #ifdef __BIG_ENDIAN_BITFIELD
2368 left_shift_bits = bits_offset;
2369 #else
2370 left_shift_bits = BITS_PER_U128 - nr_copy_bits;
2371 #endif
2372 right_shift_bits = BITS_PER_U128 - nr_bits;
2373
2374 btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
2375 btf_int128_print(show, print_num);
2376 }
2377
2378
btf_int_bits_show(const struct btf * btf,const struct btf_type * t,void * data,u8 bits_offset,struct btf_show * show)2379 static void btf_int_bits_show(const struct btf *btf,
2380 const struct btf_type *t,
2381 void *data, u8 bits_offset,
2382 struct btf_show *show)
2383 {
2384 u32 int_data = btf_type_int(t);
2385 u8 nr_bits = BTF_INT_BITS(int_data);
2386 u8 total_bits_offset;
2387
2388 /*
2389 * bits_offset is at most 7.
2390 * BTF_INT_OFFSET() cannot exceed 128 bits.
2391 */
2392 total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
2393 data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
2394 bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
2395 btf_bitfield_show(data, bits_offset, nr_bits, show);
2396 }
2397
btf_int_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)2398 static void btf_int_show(const struct btf *btf, const struct btf_type *t,
2399 u32 type_id, void *data, u8 bits_offset,
2400 struct btf_show *show)
2401 {
2402 u32 int_data = btf_type_int(t);
2403 u8 encoding = BTF_INT_ENCODING(int_data);
2404 bool sign = encoding & BTF_INT_SIGNED;
2405 u8 nr_bits = BTF_INT_BITS(int_data);
2406 void *safe_data;
2407
2408 safe_data = btf_show_start_type(show, t, type_id, data);
2409 if (!safe_data)
2410 return;
2411
2412 if (bits_offset || BTF_INT_OFFSET(int_data) ||
2413 BITS_PER_BYTE_MASKED(nr_bits)) {
2414 btf_int_bits_show(btf, t, safe_data, bits_offset, show);
2415 goto out;
2416 }
2417
2418 switch (nr_bits) {
2419 case 128:
2420 btf_int128_print(show, safe_data);
2421 break;
2422 case 64:
2423 if (sign)
2424 btf_show_type_value(show, "%lld", *(s64 *)safe_data);
2425 else
2426 btf_show_type_value(show, "%llu", *(u64 *)safe_data);
2427 break;
2428 case 32:
2429 if (sign)
2430 btf_show_type_value(show, "%d", *(s32 *)safe_data);
2431 else
2432 btf_show_type_value(show, "%u", *(u32 *)safe_data);
2433 break;
2434 case 16:
2435 if (sign)
2436 btf_show_type_value(show, "%d", *(s16 *)safe_data);
2437 else
2438 btf_show_type_value(show, "%u", *(u16 *)safe_data);
2439 break;
2440 case 8:
2441 if (show->state.array_encoding == BTF_INT_CHAR) {
2442 /* check for null terminator */
2443 if (show->state.array_terminated)
2444 break;
2445 if (*(char *)data == '\0') {
2446 show->state.array_terminated = 1;
2447 break;
2448 }
2449 if (isprint(*(char *)data)) {
2450 btf_show_type_value(show, "'%c'",
2451 *(char *)safe_data);
2452 break;
2453 }
2454 }
2455 if (sign)
2456 btf_show_type_value(show, "%d", *(s8 *)safe_data);
2457 else
2458 btf_show_type_value(show, "%u", *(u8 *)safe_data);
2459 break;
2460 default:
2461 btf_int_bits_show(btf, t, safe_data, bits_offset, show);
2462 break;
2463 }
2464 out:
2465 btf_show_end_type(show);
2466 }
2467
2468 static const struct btf_kind_operations int_ops = {
2469 .check_meta = btf_int_check_meta,
2470 .resolve = btf_df_resolve,
2471 .check_member = btf_int_check_member,
2472 .check_kflag_member = btf_int_check_kflag_member,
2473 .log_details = btf_int_log,
2474 .show = btf_int_show,
2475 };
2476
btf_modifier_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2477 static int btf_modifier_check_member(struct btf_verifier_env *env,
2478 const struct btf_type *struct_type,
2479 const struct btf_member *member,
2480 const struct btf_type *member_type)
2481 {
2482 const struct btf_type *resolved_type;
2483 u32 resolved_type_id = member->type;
2484 struct btf_member resolved_member;
2485 struct btf *btf = env->btf;
2486
2487 resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
2488 if (!resolved_type) {
2489 btf_verifier_log_member(env, struct_type, member,
2490 "Invalid member");
2491 return -EINVAL;
2492 }
2493
2494 resolved_member = *member;
2495 resolved_member.type = resolved_type_id;
2496
2497 return btf_type_ops(resolved_type)->check_member(env, struct_type,
2498 &resolved_member,
2499 resolved_type);
2500 }
2501
btf_modifier_check_kflag_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2502 static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
2503 const struct btf_type *struct_type,
2504 const struct btf_member *member,
2505 const struct btf_type *member_type)
2506 {
2507 const struct btf_type *resolved_type;
2508 u32 resolved_type_id = member->type;
2509 struct btf_member resolved_member;
2510 struct btf *btf = env->btf;
2511
2512 resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
2513 if (!resolved_type) {
2514 btf_verifier_log_member(env, struct_type, member,
2515 "Invalid member");
2516 return -EINVAL;
2517 }
2518
2519 resolved_member = *member;
2520 resolved_member.type = resolved_type_id;
2521
2522 return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
2523 &resolved_member,
2524 resolved_type);
2525 }
2526
btf_ptr_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2527 static int btf_ptr_check_member(struct btf_verifier_env *env,
2528 const struct btf_type *struct_type,
2529 const struct btf_member *member,
2530 const struct btf_type *member_type)
2531 {
2532 u32 struct_size, struct_bits_off, bytes_offset;
2533
2534 struct_size = struct_type->size;
2535 struct_bits_off = member->offset;
2536 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
2537
2538 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
2539 btf_verifier_log_member(env, struct_type, member,
2540 "Member is not byte aligned");
2541 return -EINVAL;
2542 }
2543
2544 if (struct_size - bytes_offset < sizeof(void *)) {
2545 btf_verifier_log_member(env, struct_type, member,
2546 "Member exceeds struct_size");
2547 return -EINVAL;
2548 }
2549
2550 return 0;
2551 }
2552
btf_ref_type_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)2553 static int btf_ref_type_check_meta(struct btf_verifier_env *env,
2554 const struct btf_type *t,
2555 u32 meta_left)
2556 {
2557 const char *value;
2558
2559 if (btf_type_vlen(t)) {
2560 btf_verifier_log_type(env, t, "vlen != 0");
2561 return -EINVAL;
2562 }
2563
2564 if (btf_type_kflag(t)) {
2565 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
2566 return -EINVAL;
2567 }
2568
2569 if (!BTF_TYPE_ID_VALID(t->type)) {
2570 btf_verifier_log_type(env, t, "Invalid type_id");
2571 return -EINVAL;
2572 }
2573
2574 /* typedef/type_tag type must have a valid name, and other ref types,
2575 * volatile, const, restrict, should have a null name.
2576 */
2577 if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
2578 if (!t->name_off ||
2579 !btf_name_valid_identifier(env->btf, t->name_off)) {
2580 btf_verifier_log_type(env, t, "Invalid name");
2581 return -EINVAL;
2582 }
2583 } else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
2584 value = btf_name_by_offset(env->btf, t->name_off);
2585 if (!value || !value[0]) {
2586 btf_verifier_log_type(env, t, "Invalid name");
2587 return -EINVAL;
2588 }
2589 } else {
2590 if (t->name_off) {
2591 btf_verifier_log_type(env, t, "Invalid name");
2592 return -EINVAL;
2593 }
2594 }
2595
2596 btf_verifier_log_type(env, t, NULL);
2597
2598 return 0;
2599 }
2600
btf_modifier_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)2601 static int btf_modifier_resolve(struct btf_verifier_env *env,
2602 const struct resolve_vertex *v)
2603 {
2604 const struct btf_type *t = v->t;
2605 const struct btf_type *next_type;
2606 u32 next_type_id = t->type;
2607 struct btf *btf = env->btf;
2608
2609 next_type = btf_type_by_id(btf, next_type_id);
2610 if (!next_type || btf_type_is_resolve_source_only(next_type)) {
2611 btf_verifier_log_type(env, v->t, "Invalid type_id");
2612 return -EINVAL;
2613 }
2614
2615 if (!env_type_is_resolve_sink(env, next_type) &&
2616 !env_type_is_resolved(env, next_type_id))
2617 return env_stack_push(env, next_type, next_type_id);
2618
2619 /* Figure out the resolved next_type_id with size.
2620 * They will be stored in the current modifier's
2621 * resolved_ids and resolved_sizes such that it can
2622 * save us a few type-following when we use it later (e.g. in
2623 * pretty print).
2624 */
2625 if (!btf_type_id_size(btf, &next_type_id, NULL)) {
2626 if (env_type_is_resolved(env, next_type_id))
2627 next_type = btf_type_id_resolve(btf, &next_type_id);
2628
2629 /* "typedef void new_void", "const void"...etc */
2630 if (!btf_type_is_void(next_type) &&
2631 !btf_type_is_fwd(next_type) &&
2632 !btf_type_is_func_proto(next_type)) {
2633 btf_verifier_log_type(env, v->t, "Invalid type_id");
2634 return -EINVAL;
2635 }
2636 }
2637
2638 env_stack_pop_resolved(env, next_type_id, 0);
2639
2640 return 0;
2641 }
2642
btf_var_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)2643 static int btf_var_resolve(struct btf_verifier_env *env,
2644 const struct resolve_vertex *v)
2645 {
2646 const struct btf_type *next_type;
2647 const struct btf_type *t = v->t;
2648 u32 next_type_id = t->type;
2649 struct btf *btf = env->btf;
2650
2651 next_type = btf_type_by_id(btf, next_type_id);
2652 if (!next_type || btf_type_is_resolve_source_only(next_type)) {
2653 btf_verifier_log_type(env, v->t, "Invalid type_id");
2654 return -EINVAL;
2655 }
2656
2657 if (!env_type_is_resolve_sink(env, next_type) &&
2658 !env_type_is_resolved(env, next_type_id))
2659 return env_stack_push(env, next_type, next_type_id);
2660
2661 if (btf_type_is_modifier(next_type)) {
2662 const struct btf_type *resolved_type;
2663 u32 resolved_type_id;
2664
2665 resolved_type_id = next_type_id;
2666 resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
2667
2668 if (btf_type_is_ptr(resolved_type) &&
2669 !env_type_is_resolve_sink(env, resolved_type) &&
2670 !env_type_is_resolved(env, resolved_type_id))
2671 return env_stack_push(env, resolved_type,
2672 resolved_type_id);
2673 }
2674
2675 /* We must resolve to something concrete at this point, no
2676 * forward types or similar that would resolve to size of
2677 * zero is allowed.
2678 */
2679 if (!btf_type_id_size(btf, &next_type_id, NULL)) {
2680 btf_verifier_log_type(env, v->t, "Invalid type_id");
2681 return -EINVAL;
2682 }
2683
2684 env_stack_pop_resolved(env, next_type_id, 0);
2685
2686 return 0;
2687 }
2688
btf_ptr_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)2689 static int btf_ptr_resolve(struct btf_verifier_env *env,
2690 const struct resolve_vertex *v)
2691 {
2692 const struct btf_type *next_type;
2693 const struct btf_type *t = v->t;
2694 u32 next_type_id = t->type;
2695 struct btf *btf = env->btf;
2696
2697 next_type = btf_type_by_id(btf, next_type_id);
2698 if (!next_type || btf_type_is_resolve_source_only(next_type)) {
2699 btf_verifier_log_type(env, v->t, "Invalid type_id");
2700 return -EINVAL;
2701 }
2702
2703 if (!env_type_is_resolve_sink(env, next_type) &&
2704 !env_type_is_resolved(env, next_type_id))
2705 return env_stack_push(env, next_type, next_type_id);
2706
2707 /* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
2708 * the modifier may have stopped resolving when it was resolved
2709 * to a ptr (last-resolved-ptr).
2710 *
2711 * We now need to continue from the last-resolved-ptr to
2712 * ensure the last-resolved-ptr will not referring back to
2713 * the current ptr (t).
2714 */
2715 if (btf_type_is_modifier(next_type)) {
2716 const struct btf_type *resolved_type;
2717 u32 resolved_type_id;
2718
2719 resolved_type_id = next_type_id;
2720 resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
2721
2722 if (btf_type_is_ptr(resolved_type) &&
2723 !env_type_is_resolve_sink(env, resolved_type) &&
2724 !env_type_is_resolved(env, resolved_type_id))
2725 return env_stack_push(env, resolved_type,
2726 resolved_type_id);
2727 }
2728
2729 if (!btf_type_id_size(btf, &next_type_id, NULL)) {
2730 if (env_type_is_resolved(env, next_type_id))
2731 next_type = btf_type_id_resolve(btf, &next_type_id);
2732
2733 if (!btf_type_is_void(next_type) &&
2734 !btf_type_is_fwd(next_type) &&
2735 !btf_type_is_func_proto(next_type)) {
2736 btf_verifier_log_type(env, v->t, "Invalid type_id");
2737 return -EINVAL;
2738 }
2739 }
2740
2741 env_stack_pop_resolved(env, next_type_id, 0);
2742
2743 return 0;
2744 }
2745
btf_modifier_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)2746 static void btf_modifier_show(const struct btf *btf,
2747 const struct btf_type *t,
2748 u32 type_id, void *data,
2749 u8 bits_offset, struct btf_show *show)
2750 {
2751 if (btf->resolved_ids)
2752 t = btf_type_id_resolve(btf, &type_id);
2753 else
2754 t = btf_type_skip_modifiers(btf, type_id, NULL);
2755
2756 btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
2757 }
2758
btf_var_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)2759 static void btf_var_show(const struct btf *btf, const struct btf_type *t,
2760 u32 type_id, void *data, u8 bits_offset,
2761 struct btf_show *show)
2762 {
2763 t = btf_type_id_resolve(btf, &type_id);
2764
2765 btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
2766 }
2767
btf_ptr_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)2768 static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
2769 u32 type_id, void *data, u8 bits_offset,
2770 struct btf_show *show)
2771 {
2772 void *safe_data;
2773
2774 safe_data = btf_show_start_type(show, t, type_id, data);
2775 if (!safe_data)
2776 return;
2777
2778 /* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
2779 if (show->flags & BTF_SHOW_PTR_RAW)
2780 btf_show_type_value(show, "0x%px", *(void **)safe_data);
2781 else
2782 btf_show_type_value(show, "0x%p", *(void **)safe_data);
2783 btf_show_end_type(show);
2784 }
2785
btf_ref_type_log(struct btf_verifier_env * env,const struct btf_type * t)2786 static void btf_ref_type_log(struct btf_verifier_env *env,
2787 const struct btf_type *t)
2788 {
2789 btf_verifier_log(env, "type_id=%u", t->type);
2790 }
2791
2792 static struct btf_kind_operations modifier_ops = {
2793 .check_meta = btf_ref_type_check_meta,
2794 .resolve = btf_modifier_resolve,
2795 .check_member = btf_modifier_check_member,
2796 .check_kflag_member = btf_modifier_check_kflag_member,
2797 .log_details = btf_ref_type_log,
2798 .show = btf_modifier_show,
2799 };
2800
2801 static struct btf_kind_operations ptr_ops = {
2802 .check_meta = btf_ref_type_check_meta,
2803 .resolve = btf_ptr_resolve,
2804 .check_member = btf_ptr_check_member,
2805 .check_kflag_member = btf_generic_check_kflag_member,
2806 .log_details = btf_ref_type_log,
2807 .show = btf_ptr_show,
2808 };
2809
btf_fwd_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)2810 static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
2811 const struct btf_type *t,
2812 u32 meta_left)
2813 {
2814 if (btf_type_vlen(t)) {
2815 btf_verifier_log_type(env, t, "vlen != 0");
2816 return -EINVAL;
2817 }
2818
2819 if (t->type) {
2820 btf_verifier_log_type(env, t, "type != 0");
2821 return -EINVAL;
2822 }
2823
2824 /* fwd type must have a valid name */
2825 if (!t->name_off ||
2826 !btf_name_valid_identifier(env->btf, t->name_off)) {
2827 btf_verifier_log_type(env, t, "Invalid name");
2828 return -EINVAL;
2829 }
2830
2831 btf_verifier_log_type(env, t, NULL);
2832
2833 return 0;
2834 }
2835
btf_fwd_type_log(struct btf_verifier_env * env,const struct btf_type * t)2836 static void btf_fwd_type_log(struct btf_verifier_env *env,
2837 const struct btf_type *t)
2838 {
2839 btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
2840 }
2841
2842 static struct btf_kind_operations fwd_ops = {
2843 .check_meta = btf_fwd_check_meta,
2844 .resolve = btf_df_resolve,
2845 .check_member = btf_df_check_member,
2846 .check_kflag_member = btf_df_check_kflag_member,
2847 .log_details = btf_fwd_type_log,
2848 .show = btf_df_show,
2849 };
2850
btf_array_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)2851 static int btf_array_check_member(struct btf_verifier_env *env,
2852 const struct btf_type *struct_type,
2853 const struct btf_member *member,
2854 const struct btf_type *member_type)
2855 {
2856 u32 struct_bits_off = member->offset;
2857 u32 struct_size, bytes_offset;
2858 u32 array_type_id, array_size;
2859 struct btf *btf = env->btf;
2860
2861 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
2862 btf_verifier_log_member(env, struct_type, member,
2863 "Member is not byte aligned");
2864 return -EINVAL;
2865 }
2866
2867 array_type_id = member->type;
2868 btf_type_id_size(btf, &array_type_id, &array_size);
2869 struct_size = struct_type->size;
2870 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
2871 if (struct_size - bytes_offset < array_size) {
2872 btf_verifier_log_member(env, struct_type, member,
2873 "Member exceeds struct_size");
2874 return -EINVAL;
2875 }
2876
2877 return 0;
2878 }
2879
btf_array_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)2880 static s32 btf_array_check_meta(struct btf_verifier_env *env,
2881 const struct btf_type *t,
2882 u32 meta_left)
2883 {
2884 const struct btf_array *array = btf_type_array(t);
2885 u32 meta_needed = sizeof(*array);
2886
2887 if (meta_left < meta_needed) {
2888 btf_verifier_log_basic(env, t,
2889 "meta_left:%u meta_needed:%u",
2890 meta_left, meta_needed);
2891 return -EINVAL;
2892 }
2893
2894 /* array type should not have a name */
2895 if (t->name_off) {
2896 btf_verifier_log_type(env, t, "Invalid name");
2897 return -EINVAL;
2898 }
2899
2900 if (btf_type_vlen(t)) {
2901 btf_verifier_log_type(env, t, "vlen != 0");
2902 return -EINVAL;
2903 }
2904
2905 if (btf_type_kflag(t)) {
2906 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
2907 return -EINVAL;
2908 }
2909
2910 if (t->size) {
2911 btf_verifier_log_type(env, t, "size != 0");
2912 return -EINVAL;
2913 }
2914
2915 /* Array elem type and index type cannot be in type void,
2916 * so !array->type and !array->index_type are not allowed.
2917 */
2918 if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
2919 btf_verifier_log_type(env, t, "Invalid elem");
2920 return -EINVAL;
2921 }
2922
2923 if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
2924 btf_verifier_log_type(env, t, "Invalid index");
2925 return -EINVAL;
2926 }
2927
2928 btf_verifier_log_type(env, t, NULL);
2929
2930 return meta_needed;
2931 }
2932
btf_array_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)2933 static int btf_array_resolve(struct btf_verifier_env *env,
2934 const struct resolve_vertex *v)
2935 {
2936 const struct btf_array *array = btf_type_array(v->t);
2937 const struct btf_type *elem_type, *index_type;
2938 u32 elem_type_id, index_type_id;
2939 struct btf *btf = env->btf;
2940 u32 elem_size;
2941
2942 /* Check array->index_type */
2943 index_type_id = array->index_type;
2944 index_type = btf_type_by_id(btf, index_type_id);
2945 if (btf_type_nosize_or_null(index_type) ||
2946 btf_type_is_resolve_source_only(index_type)) {
2947 btf_verifier_log_type(env, v->t, "Invalid index");
2948 return -EINVAL;
2949 }
2950
2951 if (!env_type_is_resolve_sink(env, index_type) &&
2952 !env_type_is_resolved(env, index_type_id))
2953 return env_stack_push(env, index_type, index_type_id);
2954
2955 index_type = btf_type_id_size(btf, &index_type_id, NULL);
2956 if (!index_type || !btf_type_is_int(index_type) ||
2957 !btf_type_int_is_regular(index_type)) {
2958 btf_verifier_log_type(env, v->t, "Invalid index");
2959 return -EINVAL;
2960 }
2961
2962 /* Check array->type */
2963 elem_type_id = array->type;
2964 elem_type = btf_type_by_id(btf, elem_type_id);
2965 if (btf_type_nosize_or_null(elem_type) ||
2966 btf_type_is_resolve_source_only(elem_type)) {
2967 btf_verifier_log_type(env, v->t,
2968 "Invalid elem");
2969 return -EINVAL;
2970 }
2971
2972 if (!env_type_is_resolve_sink(env, elem_type) &&
2973 !env_type_is_resolved(env, elem_type_id))
2974 return env_stack_push(env, elem_type, elem_type_id);
2975
2976 elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
2977 if (!elem_type) {
2978 btf_verifier_log_type(env, v->t, "Invalid elem");
2979 return -EINVAL;
2980 }
2981
2982 if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
2983 btf_verifier_log_type(env, v->t, "Invalid array of int");
2984 return -EINVAL;
2985 }
2986
2987 if (array->nelems && elem_size > U32_MAX / array->nelems) {
2988 btf_verifier_log_type(env, v->t,
2989 "Array size overflows U32_MAX");
2990 return -EINVAL;
2991 }
2992
2993 env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);
2994
2995 return 0;
2996 }
2997
btf_array_log(struct btf_verifier_env * env,const struct btf_type * t)2998 static void btf_array_log(struct btf_verifier_env *env,
2999 const struct btf_type *t)
3000 {
3001 const struct btf_array *array = btf_type_array(t);
3002
3003 btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
3004 array->type, array->index_type, array->nelems);
3005 }
3006
__btf_array_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)3007 static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
3008 u32 type_id, void *data, u8 bits_offset,
3009 struct btf_show *show)
3010 {
3011 const struct btf_array *array = btf_type_array(t);
3012 const struct btf_kind_operations *elem_ops;
3013 const struct btf_type *elem_type;
3014 u32 i, elem_size = 0, elem_type_id;
3015 u16 encoding = 0;
3016
3017 elem_type_id = array->type;
3018 elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
3019 if (elem_type && btf_type_has_size(elem_type))
3020 elem_size = elem_type->size;
3021
3022 if (elem_type && btf_type_is_int(elem_type)) {
3023 u32 int_type = btf_type_int(elem_type);
3024
3025 encoding = BTF_INT_ENCODING(int_type);
3026
3027 /*
3028 * BTF_INT_CHAR encoding never seems to be set for
3029 * char arrays, so if size is 1 and element is
3030 * printable as a char, we'll do that.
3031 */
3032 if (elem_size == 1)
3033 encoding = BTF_INT_CHAR;
3034 }
3035
3036 if (!btf_show_start_array_type(show, t, type_id, encoding, data))
3037 return;
3038
3039 if (!elem_type)
3040 goto out;
3041 elem_ops = btf_type_ops(elem_type);
3042
3043 for (i = 0; i < array->nelems; i++) {
3044
3045 btf_show_start_array_member(show);
3046
3047 elem_ops->show(btf, elem_type, elem_type_id, data,
3048 bits_offset, show);
3049 data += elem_size;
3050
3051 btf_show_end_array_member(show);
3052
3053 if (show->state.array_terminated)
3054 break;
3055 }
3056 out:
3057 btf_show_end_array_type(show);
3058 }
3059
btf_array_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)3060 static void btf_array_show(const struct btf *btf, const struct btf_type *t,
3061 u32 type_id, void *data, u8 bits_offset,
3062 struct btf_show *show)
3063 {
3064 const struct btf_member *m = show->state.member;
3065
3066 /*
3067 * First check if any members would be shown (are non-zero).
3068 * See comments above "struct btf_show" definition for more
3069 * details on how this works at a high-level.
3070 */
3071 if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
3072 if (!show->state.depth_check) {
3073 show->state.depth_check = show->state.depth + 1;
3074 show->state.depth_to_show = 0;
3075 }
3076 __btf_array_show(btf, t, type_id, data, bits_offset, show);
3077 show->state.member = m;
3078
3079 if (show->state.depth_check != show->state.depth + 1)
3080 return;
3081 show->state.depth_check = 0;
3082
3083 if (show->state.depth_to_show <= show->state.depth)
3084 return;
3085 /*
3086 * Reaching here indicates we have recursed and found
3087 * non-zero array member(s).
3088 */
3089 }
3090 __btf_array_show(btf, t, type_id, data, bits_offset, show);
3091 }
3092
3093 static struct btf_kind_operations array_ops = {
3094 .check_meta = btf_array_check_meta,
3095 .resolve = btf_array_resolve,
3096 .check_member = btf_array_check_member,
3097 .check_kflag_member = btf_generic_check_kflag_member,
3098 .log_details = btf_array_log,
3099 .show = btf_array_show,
3100 };
3101
btf_struct_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)3102 static int btf_struct_check_member(struct btf_verifier_env *env,
3103 const struct btf_type *struct_type,
3104 const struct btf_member *member,
3105 const struct btf_type *member_type)
3106 {
3107 u32 struct_bits_off = member->offset;
3108 u32 struct_size, bytes_offset;
3109
3110 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
3111 btf_verifier_log_member(env, struct_type, member,
3112 "Member is not byte aligned");
3113 return -EINVAL;
3114 }
3115
3116 struct_size = struct_type->size;
3117 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
3118 if (struct_size - bytes_offset < member_type->size) {
3119 btf_verifier_log_member(env, struct_type, member,
3120 "Member exceeds struct_size");
3121 return -EINVAL;
3122 }
3123
3124 return 0;
3125 }
3126
btf_struct_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)3127 static s32 btf_struct_check_meta(struct btf_verifier_env *env,
3128 const struct btf_type *t,
3129 u32 meta_left)
3130 {
3131 bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
3132 const struct btf_member *member;
3133 u32 meta_needed, last_offset;
3134 struct btf *btf = env->btf;
3135 u32 struct_size = t->size;
3136 u32 offset;
3137 u16 i;
3138
3139 meta_needed = btf_type_vlen(t) * sizeof(*member);
3140 if (meta_left < meta_needed) {
3141 btf_verifier_log_basic(env, t,
3142 "meta_left:%u meta_needed:%u",
3143 meta_left, meta_needed);
3144 return -EINVAL;
3145 }
3146
3147 /* struct type either no name or a valid one */
3148 if (t->name_off &&
3149 !btf_name_valid_identifier(env->btf, t->name_off)) {
3150 btf_verifier_log_type(env, t, "Invalid name");
3151 return -EINVAL;
3152 }
3153
3154 btf_verifier_log_type(env, t, NULL);
3155
3156 last_offset = 0;
3157 for_each_member(i, t, member) {
3158 if (!btf_name_offset_valid(btf, member->name_off)) {
3159 btf_verifier_log_member(env, t, member,
3160 "Invalid member name_offset:%u",
3161 member->name_off);
3162 return -EINVAL;
3163 }
3164
3165 /* struct member either no name or a valid one */
3166 if (member->name_off &&
3167 !btf_name_valid_identifier(btf, member->name_off)) {
3168 btf_verifier_log_member(env, t, member, "Invalid name");
3169 return -EINVAL;
3170 }
3171 /* A member cannot be in type void */
3172 if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
3173 btf_verifier_log_member(env, t, member,
3174 "Invalid type_id");
3175 return -EINVAL;
3176 }
3177
3178 offset = __btf_member_bit_offset(t, member);
3179 if (is_union && offset) {
3180 btf_verifier_log_member(env, t, member,
3181 "Invalid member bits_offset");
3182 return -EINVAL;
3183 }
3184
3185 /*
3186 * ">" instead of ">=" because the last member could be
3187 * "char a[0];"
3188 */
3189 if (last_offset > offset) {
3190 btf_verifier_log_member(env, t, member,
3191 "Invalid member bits_offset");
3192 return -EINVAL;
3193 }
3194
3195 if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
3196 btf_verifier_log_member(env, t, member,
3197 "Member bits_offset exceeds its struct size");
3198 return -EINVAL;
3199 }
3200
3201 btf_verifier_log_member(env, t, member, NULL);
3202 last_offset = offset;
3203 }
3204
3205 return meta_needed;
3206 }
3207
btf_struct_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)3208 static int btf_struct_resolve(struct btf_verifier_env *env,
3209 const struct resolve_vertex *v)
3210 {
3211 const struct btf_member *member;
3212 int err;
3213 u16 i;
3214
3215 /* Before continue resolving the next_member,
3216 * ensure the last member is indeed resolved to a
3217 * type with size info.
3218 */
3219 if (v->next_member) {
3220 const struct btf_type *last_member_type;
3221 const struct btf_member *last_member;
3222 u32 last_member_type_id;
3223
3224 last_member = btf_type_member(v->t) + v->next_member - 1;
3225 last_member_type_id = last_member->type;
3226 if (WARN_ON_ONCE(!env_type_is_resolved(env,
3227 last_member_type_id)))
3228 return -EINVAL;
3229
3230 last_member_type = btf_type_by_id(env->btf,
3231 last_member_type_id);
3232 if (btf_type_kflag(v->t))
3233 err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
3234 last_member,
3235 last_member_type);
3236 else
3237 err = btf_type_ops(last_member_type)->check_member(env, v->t,
3238 last_member,
3239 last_member_type);
3240 if (err)
3241 return err;
3242 }
3243
3244 for_each_member_from(i, v->next_member, v->t, member) {
3245 u32 member_type_id = member->type;
3246 const struct btf_type *member_type = btf_type_by_id(env->btf,
3247 member_type_id);
3248
3249 if (btf_type_nosize_or_null(member_type) ||
3250 btf_type_is_resolve_source_only(member_type)) {
3251 btf_verifier_log_member(env, v->t, member,
3252 "Invalid member");
3253 return -EINVAL;
3254 }
3255
3256 if (!env_type_is_resolve_sink(env, member_type) &&
3257 !env_type_is_resolved(env, member_type_id)) {
3258 env_stack_set_next_member(env, i + 1);
3259 return env_stack_push(env, member_type, member_type_id);
3260 }
3261
3262 if (btf_type_kflag(v->t))
3263 err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
3264 member,
3265 member_type);
3266 else
3267 err = btf_type_ops(member_type)->check_member(env, v->t,
3268 member,
3269 member_type);
3270 if (err)
3271 return err;
3272 }
3273
3274 env_stack_pop_resolved(env, 0, 0);
3275
3276 return 0;
3277 }
3278
btf_struct_log(struct btf_verifier_env * env,const struct btf_type * t)3279 static void btf_struct_log(struct btf_verifier_env *env,
3280 const struct btf_type *t)
3281 {
3282 btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
3283 }
3284
3285 enum {
3286 BTF_FIELD_IGNORE = 0,
3287 BTF_FIELD_FOUND = 1,
3288 };
3289
3290 struct btf_field_info {
3291 enum btf_field_type type;
3292 u32 off;
3293 union {
3294 struct {
3295 u32 type_id;
3296 } kptr;
3297 struct {
3298 const char *node_name;
3299 u32 value_btf_id;
3300 } graph_root;
3301 };
3302 };
3303
btf_find_struct(const struct btf * btf,const struct btf_type * t,u32 off,int sz,enum btf_field_type field_type,struct btf_field_info * info)3304 static int btf_find_struct(const struct btf *btf, const struct btf_type *t,
3305 u32 off, int sz, enum btf_field_type field_type,
3306 struct btf_field_info *info)
3307 {
3308 if (!__btf_type_is_struct(t))
3309 return BTF_FIELD_IGNORE;
3310 if (t->size != sz)
3311 return BTF_FIELD_IGNORE;
3312 info->type = field_type;
3313 info->off = off;
3314 return BTF_FIELD_FOUND;
3315 }
3316
btf_find_kptr(const struct btf * btf,const struct btf_type * t,u32 off,int sz,struct btf_field_info * info)3317 static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
3318 u32 off, int sz, struct btf_field_info *info)
3319 {
3320 enum btf_field_type type;
3321 u32 res_id;
3322
3323 /* Permit modifiers on the pointer itself */
3324 if (btf_type_is_volatile(t))
3325 t = btf_type_by_id(btf, t->type);
3326 /* For PTR, sz is always == 8 */
3327 if (!btf_type_is_ptr(t))
3328 return BTF_FIELD_IGNORE;
3329 t = btf_type_by_id(btf, t->type);
3330
3331 if (!btf_type_is_type_tag(t))
3332 return BTF_FIELD_IGNORE;
3333 /* Reject extra tags */
3334 if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
3335 return -EINVAL;
3336 if (!strcmp("kptr_untrusted", __btf_name_by_offset(btf, t->name_off)))
3337 type = BPF_KPTR_UNREF;
3338 else if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
3339 type = BPF_KPTR_REF;
3340 else if (!strcmp("percpu_kptr", __btf_name_by_offset(btf, t->name_off)))
3341 type = BPF_KPTR_PERCPU;
3342 else
3343 return -EINVAL;
3344
3345 /* Get the base type */
3346 t = btf_type_skip_modifiers(btf, t->type, &res_id);
3347 /* Only pointer to struct is allowed */
3348 if (!__btf_type_is_struct(t))
3349 return -EINVAL;
3350
3351 info->type = type;
3352 info->off = off;
3353 info->kptr.type_id = res_id;
3354 return BTF_FIELD_FOUND;
3355 }
3356
btf_find_next_decl_tag(const struct btf * btf,const struct btf_type * pt,int comp_idx,const char * tag_key,int last_id)3357 int btf_find_next_decl_tag(const struct btf *btf, const struct btf_type *pt,
3358 int comp_idx, const char *tag_key, int last_id)
3359 {
3360 int len = strlen(tag_key);
3361 int i, n;
3362
3363 for (i = last_id + 1, n = btf_nr_types(btf); i < n; i++) {
3364 const struct btf_type *t = btf_type_by_id(btf, i);
3365
3366 if (!btf_type_is_decl_tag(t))
3367 continue;
3368 if (pt != btf_type_by_id(btf, t->type))
3369 continue;
3370 if (btf_type_decl_tag(t)->component_idx != comp_idx)
3371 continue;
3372 if (strncmp(__btf_name_by_offset(btf, t->name_off), tag_key, len))
3373 continue;
3374 return i;
3375 }
3376 return -ENOENT;
3377 }
3378
btf_find_decl_tag_value(const struct btf * btf,const struct btf_type * pt,int comp_idx,const char * tag_key)3379 const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type *pt,
3380 int comp_idx, const char *tag_key)
3381 {
3382 const char *value = NULL;
3383 const struct btf_type *t;
3384 int len, id;
3385
3386 id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key, 0);
3387 if (id < 0)
3388 return ERR_PTR(id);
3389
3390 t = btf_type_by_id(btf, id);
3391 len = strlen(tag_key);
3392 value = __btf_name_by_offset(btf, t->name_off) + len;
3393
3394 /* Prevent duplicate entries for same type */
3395 id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key, id);
3396 if (id >= 0)
3397 return ERR_PTR(-EEXIST);
3398
3399 return value;
3400 }
3401
3402 static int
btf_find_graph_root(const struct btf * btf,const struct btf_type * pt,const struct btf_type * t,int comp_idx,u32 off,int sz,struct btf_field_info * info,enum btf_field_type head_type)3403 btf_find_graph_root(const struct btf *btf, const struct btf_type *pt,
3404 const struct btf_type *t, int comp_idx, u32 off,
3405 int sz, struct btf_field_info *info,
3406 enum btf_field_type head_type)
3407 {
3408 const char *node_field_name;
3409 const char *value_type;
3410 s32 id;
3411
3412 if (!__btf_type_is_struct(t))
3413 return BTF_FIELD_IGNORE;
3414 if (t->size != sz)
3415 return BTF_FIELD_IGNORE;
3416 value_type = btf_find_decl_tag_value(btf, pt, comp_idx, "contains:");
3417 if (IS_ERR(value_type))
3418 return -EINVAL;
3419 node_field_name = strstr(value_type, ":");
3420 if (!node_field_name)
3421 return -EINVAL;
3422 value_type = kstrndup(value_type, node_field_name - value_type, GFP_KERNEL | __GFP_NOWARN);
3423 if (!value_type)
3424 return -ENOMEM;
3425 id = btf_find_by_name_kind(btf, value_type, BTF_KIND_STRUCT);
3426 kfree(value_type);
3427 if (id < 0)
3428 return id;
3429 node_field_name++;
3430 if (str_is_empty(node_field_name))
3431 return -EINVAL;
3432 info->type = head_type;
3433 info->off = off;
3434 info->graph_root.value_btf_id = id;
3435 info->graph_root.node_name = node_field_name;
3436 return BTF_FIELD_FOUND;
3437 }
3438
3439 #define field_mask_test_name(field_type, field_type_str) \
3440 if (field_mask & field_type && !strcmp(name, field_type_str)) { \
3441 type = field_type; \
3442 goto end; \
3443 }
3444
btf_get_field_type(const char * name,u32 field_mask,u32 * seen_mask,int * align,int * sz)3445 static int btf_get_field_type(const char *name, u32 field_mask, u32 *seen_mask,
3446 int *align, int *sz)
3447 {
3448 int type = 0;
3449
3450 if (field_mask & BPF_SPIN_LOCK) {
3451 if (!strcmp(name, "bpf_spin_lock")) {
3452 if (*seen_mask & BPF_SPIN_LOCK)
3453 return -E2BIG;
3454 *seen_mask |= BPF_SPIN_LOCK;
3455 type = BPF_SPIN_LOCK;
3456 goto end;
3457 }
3458 }
3459 if (field_mask & BPF_TIMER) {
3460 if (!strcmp(name, "bpf_timer")) {
3461 if (*seen_mask & BPF_TIMER)
3462 return -E2BIG;
3463 *seen_mask |= BPF_TIMER;
3464 type = BPF_TIMER;
3465 goto end;
3466 }
3467 }
3468 if (field_mask & BPF_WORKQUEUE) {
3469 if (!strcmp(name, "bpf_wq")) {
3470 if (*seen_mask & BPF_WORKQUEUE)
3471 return -E2BIG;
3472 *seen_mask |= BPF_WORKQUEUE;
3473 type = BPF_WORKQUEUE;
3474 goto end;
3475 }
3476 }
3477 field_mask_test_name(BPF_LIST_HEAD, "bpf_list_head");
3478 field_mask_test_name(BPF_LIST_NODE, "bpf_list_node");
3479 field_mask_test_name(BPF_RB_ROOT, "bpf_rb_root");
3480 field_mask_test_name(BPF_RB_NODE, "bpf_rb_node");
3481 field_mask_test_name(BPF_REFCOUNT, "bpf_refcount");
3482
3483 /* Only return BPF_KPTR when all other types with matchable names fail */
3484 if (field_mask & BPF_KPTR) {
3485 type = BPF_KPTR_REF;
3486 goto end;
3487 }
3488 return 0;
3489 end:
3490 *sz = btf_field_type_size(type);
3491 *align = btf_field_type_align(type);
3492 return type;
3493 }
3494
3495 #undef field_mask_test_name
3496
btf_find_struct_field(const struct btf * btf,const struct btf_type * t,u32 field_mask,struct btf_field_info * info,int info_cnt)3497 static int btf_find_struct_field(const struct btf *btf,
3498 const struct btf_type *t, u32 field_mask,
3499 struct btf_field_info *info, int info_cnt)
3500 {
3501 int ret, idx = 0, align, sz, field_type;
3502 const struct btf_member *member;
3503 struct btf_field_info tmp;
3504 u32 i, off, seen_mask = 0;
3505
3506 for_each_member(i, t, member) {
3507 const struct btf_type *member_type = btf_type_by_id(btf,
3508 member->type);
3509
3510 field_type = btf_get_field_type(__btf_name_by_offset(btf, member_type->name_off),
3511 field_mask, &seen_mask, &align, &sz);
3512 if (field_type == 0)
3513 continue;
3514 if (field_type < 0)
3515 return field_type;
3516
3517 off = __btf_member_bit_offset(t, member);
3518 if (off % 8)
3519 /* valid C code cannot generate such BTF */
3520 return -EINVAL;
3521 off /= 8;
3522 if (off % align)
3523 continue;
3524
3525 switch (field_type) {
3526 case BPF_SPIN_LOCK:
3527 case BPF_TIMER:
3528 case BPF_WORKQUEUE:
3529 case BPF_LIST_NODE:
3530 case BPF_RB_NODE:
3531 case BPF_REFCOUNT:
3532 ret = btf_find_struct(btf, member_type, off, sz, field_type,
3533 idx < info_cnt ? &info[idx] : &tmp);
3534 if (ret < 0)
3535 return ret;
3536 break;
3537 case BPF_KPTR_UNREF:
3538 case BPF_KPTR_REF:
3539 case BPF_KPTR_PERCPU:
3540 ret = btf_find_kptr(btf, member_type, off, sz,
3541 idx < info_cnt ? &info[idx] : &tmp);
3542 if (ret < 0)
3543 return ret;
3544 break;
3545 case BPF_LIST_HEAD:
3546 case BPF_RB_ROOT:
3547 ret = btf_find_graph_root(btf, t, member_type,
3548 i, off, sz,
3549 idx < info_cnt ? &info[idx] : &tmp,
3550 field_type);
3551 if (ret < 0)
3552 return ret;
3553 break;
3554 default:
3555 return -EFAULT;
3556 }
3557
3558 if (ret == BTF_FIELD_IGNORE)
3559 continue;
3560 if (idx >= info_cnt)
3561 return -E2BIG;
3562 ++idx;
3563 }
3564 return idx;
3565 }
3566
btf_find_datasec_var(const struct btf * btf,const struct btf_type * t,u32 field_mask,struct btf_field_info * info,int info_cnt)3567 static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
3568 u32 field_mask, struct btf_field_info *info,
3569 int info_cnt)
3570 {
3571 int ret, idx = 0, align, sz, field_type;
3572 const struct btf_var_secinfo *vsi;
3573 struct btf_field_info tmp;
3574 u32 i, off, seen_mask = 0;
3575
3576 for_each_vsi(i, t, vsi) {
3577 const struct btf_type *var = btf_type_by_id(btf, vsi->type);
3578 const struct btf_type *var_type = btf_type_by_id(btf, var->type);
3579
3580 field_type = btf_get_field_type(__btf_name_by_offset(btf, var_type->name_off),
3581 field_mask, &seen_mask, &align, &sz);
3582 if (field_type == 0)
3583 continue;
3584 if (field_type < 0)
3585 return field_type;
3586
3587 off = vsi->offset;
3588 if (vsi->size != sz)
3589 continue;
3590 if (off % align)
3591 continue;
3592
3593 switch (field_type) {
3594 case BPF_SPIN_LOCK:
3595 case BPF_TIMER:
3596 case BPF_WORKQUEUE:
3597 case BPF_LIST_NODE:
3598 case BPF_RB_NODE:
3599 case BPF_REFCOUNT:
3600 ret = btf_find_struct(btf, var_type, off, sz, field_type,
3601 idx < info_cnt ? &info[idx] : &tmp);
3602 if (ret < 0)
3603 return ret;
3604 break;
3605 case BPF_KPTR_UNREF:
3606 case BPF_KPTR_REF:
3607 case BPF_KPTR_PERCPU:
3608 ret = btf_find_kptr(btf, var_type, off, sz,
3609 idx < info_cnt ? &info[idx] : &tmp);
3610 if (ret < 0)
3611 return ret;
3612 break;
3613 case BPF_LIST_HEAD:
3614 case BPF_RB_ROOT:
3615 ret = btf_find_graph_root(btf, var, var_type,
3616 -1, off, sz,
3617 idx < info_cnt ? &info[idx] : &tmp,
3618 field_type);
3619 if (ret < 0)
3620 return ret;
3621 break;
3622 default:
3623 return -EFAULT;
3624 }
3625
3626 if (ret == BTF_FIELD_IGNORE)
3627 continue;
3628 if (idx >= info_cnt)
3629 return -E2BIG;
3630 ++idx;
3631 }
3632 return idx;
3633 }
3634
btf_find_field(const struct btf * btf,const struct btf_type * t,u32 field_mask,struct btf_field_info * info,int info_cnt)3635 static int btf_find_field(const struct btf *btf, const struct btf_type *t,
3636 u32 field_mask, struct btf_field_info *info,
3637 int info_cnt)
3638 {
3639 if (__btf_type_is_struct(t))
3640 return btf_find_struct_field(btf, t, field_mask, info, info_cnt);
3641 else if (btf_type_is_datasec(t))
3642 return btf_find_datasec_var(btf, t, field_mask, info, info_cnt);
3643 return -EINVAL;
3644 }
3645
btf_parse_kptr(const struct btf * btf,struct btf_field * field,struct btf_field_info * info)3646 static int btf_parse_kptr(const struct btf *btf, struct btf_field *field,
3647 struct btf_field_info *info)
3648 {
3649 struct module *mod = NULL;
3650 const struct btf_type *t;
3651 /* If a matching btf type is found in kernel or module BTFs, kptr_ref
3652 * is that BTF, otherwise it's program BTF
3653 */
3654 struct btf *kptr_btf;
3655 int ret;
3656 s32 id;
3657
3658 /* Find type in map BTF, and use it to look up the matching type
3659 * in vmlinux or module BTFs, by name and kind.
3660 */
3661 t = btf_type_by_id(btf, info->kptr.type_id);
3662 id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info),
3663 &kptr_btf);
3664 if (id == -ENOENT) {
3665 /* btf_parse_kptr should only be called w/ btf = program BTF */
3666 WARN_ON_ONCE(btf_is_kernel(btf));
3667
3668 /* Type exists only in program BTF. Assume that it's a MEM_ALLOC
3669 * kptr allocated via bpf_obj_new
3670 */
3671 field->kptr.dtor = NULL;
3672 id = info->kptr.type_id;
3673 kptr_btf = (struct btf *)btf;
3674 btf_get(kptr_btf);
3675 goto found_dtor;
3676 }
3677 if (id < 0)
3678 return id;
3679
3680 /* Find and stash the function pointer for the destruction function that
3681 * needs to be eventually invoked from the map free path.
3682 */
3683 if (info->type == BPF_KPTR_REF) {
3684 const struct btf_type *dtor_func;
3685 const char *dtor_func_name;
3686 unsigned long addr;
3687 s32 dtor_btf_id;
3688
3689 /* This call also serves as a whitelist of allowed objects that
3690 * can be used as a referenced pointer and be stored in a map at
3691 * the same time.
3692 */
3693 dtor_btf_id = btf_find_dtor_kfunc(kptr_btf, id);
3694 if (dtor_btf_id < 0) {
3695 ret = dtor_btf_id;
3696 goto end_btf;
3697 }
3698
3699 dtor_func = btf_type_by_id(kptr_btf, dtor_btf_id);
3700 if (!dtor_func) {
3701 ret = -ENOENT;
3702 goto end_btf;
3703 }
3704
3705 if (btf_is_module(kptr_btf)) {
3706 mod = btf_try_get_module(kptr_btf);
3707 if (!mod) {
3708 ret = -ENXIO;
3709 goto end_btf;
3710 }
3711 }
3712
3713 /* We already verified dtor_func to be btf_type_is_func
3714 * in register_btf_id_dtor_kfuncs.
3715 */
3716 dtor_func_name = __btf_name_by_offset(kptr_btf, dtor_func->name_off);
3717 addr = kallsyms_lookup_name(dtor_func_name);
3718 if (!addr) {
3719 ret = -EINVAL;
3720 goto end_mod;
3721 }
3722 field->kptr.dtor = (void *)addr;
3723 }
3724
3725 found_dtor:
3726 field->kptr.btf_id = id;
3727 field->kptr.btf = kptr_btf;
3728 field->kptr.module = mod;
3729 return 0;
3730 end_mod:
3731 module_put(mod);
3732 end_btf:
3733 btf_put(kptr_btf);
3734 return ret;
3735 }
3736
btf_parse_graph_root(const struct btf * btf,struct btf_field * field,struct btf_field_info * info,const char * node_type_name,size_t node_type_align)3737 static int btf_parse_graph_root(const struct btf *btf,
3738 struct btf_field *field,
3739 struct btf_field_info *info,
3740 const char *node_type_name,
3741 size_t node_type_align)
3742 {
3743 const struct btf_type *t, *n = NULL;
3744 const struct btf_member *member;
3745 u32 offset;
3746 int i;
3747
3748 t = btf_type_by_id(btf, info->graph_root.value_btf_id);
3749 /* We've already checked that value_btf_id is a struct type. We
3750 * just need to figure out the offset of the list_node, and
3751 * verify its type.
3752 */
3753 for_each_member(i, t, member) {
3754 if (strcmp(info->graph_root.node_name,
3755 __btf_name_by_offset(btf, member->name_off)))
3756 continue;
3757 /* Invalid BTF, two members with same name */
3758 if (n)
3759 return -EINVAL;
3760 n = btf_type_by_id(btf, member->type);
3761 if (!__btf_type_is_struct(n))
3762 return -EINVAL;
3763 if (strcmp(node_type_name, __btf_name_by_offset(btf, n->name_off)))
3764 return -EINVAL;
3765 offset = __btf_member_bit_offset(n, member);
3766 if (offset % 8)
3767 return -EINVAL;
3768 offset /= 8;
3769 if (offset % node_type_align)
3770 return -EINVAL;
3771
3772 field->graph_root.btf = (struct btf *)btf;
3773 field->graph_root.value_btf_id = info->graph_root.value_btf_id;
3774 field->graph_root.node_offset = offset;
3775 }
3776 if (!n)
3777 return -ENOENT;
3778 return 0;
3779 }
3780
btf_parse_list_head(const struct btf * btf,struct btf_field * field,struct btf_field_info * info)3781 static int btf_parse_list_head(const struct btf *btf, struct btf_field *field,
3782 struct btf_field_info *info)
3783 {
3784 return btf_parse_graph_root(btf, field, info, "bpf_list_node",
3785 __alignof__(struct bpf_list_node));
3786 }
3787
btf_parse_rb_root(const struct btf * btf,struct btf_field * field,struct btf_field_info * info)3788 static int btf_parse_rb_root(const struct btf *btf, struct btf_field *field,
3789 struct btf_field_info *info)
3790 {
3791 return btf_parse_graph_root(btf, field, info, "bpf_rb_node",
3792 __alignof__(struct bpf_rb_node));
3793 }
3794
btf_field_cmp(const void * _a,const void * _b,const void * priv)3795 static int btf_field_cmp(const void *_a, const void *_b, const void *priv)
3796 {
3797 const struct btf_field *a = (const struct btf_field *)_a;
3798 const struct btf_field *b = (const struct btf_field *)_b;
3799
3800 if (a->offset < b->offset)
3801 return -1;
3802 else if (a->offset > b->offset)
3803 return 1;
3804 return 0;
3805 }
3806
btf_parse_fields(const struct btf * btf,const struct btf_type * t,u32 field_mask,u32 value_size)3807 struct btf_record *btf_parse_fields(const struct btf *btf, const struct btf_type *t,
3808 u32 field_mask, u32 value_size)
3809 {
3810 struct btf_field_info info_arr[BTF_FIELDS_MAX];
3811 u32 next_off = 0, field_type_size;
3812 struct btf_record *rec;
3813 int ret, i, cnt;
3814
3815 ret = btf_find_field(btf, t, field_mask, info_arr, ARRAY_SIZE(info_arr));
3816 if (ret < 0)
3817 return ERR_PTR(ret);
3818 if (!ret)
3819 return NULL;
3820
3821 cnt = ret;
3822 /* This needs to be kzalloc to zero out padding and unused fields, see
3823 * comment in btf_record_equal.
3824 */
3825 rec = kzalloc(offsetof(struct btf_record, fields[cnt]), GFP_KERNEL | __GFP_NOWARN);
3826 if (!rec)
3827 return ERR_PTR(-ENOMEM);
3828
3829 rec->spin_lock_off = -EINVAL;
3830 rec->timer_off = -EINVAL;
3831 rec->wq_off = -EINVAL;
3832 rec->refcount_off = -EINVAL;
3833 for (i = 0; i < cnt; i++) {
3834 field_type_size = btf_field_type_size(info_arr[i].type);
3835 if (info_arr[i].off + field_type_size > value_size) {
3836 WARN_ONCE(1, "verifier bug off %d size %d", info_arr[i].off, value_size);
3837 ret = -EFAULT;
3838 goto end;
3839 }
3840 if (info_arr[i].off < next_off) {
3841 ret = -EEXIST;
3842 goto end;
3843 }
3844 next_off = info_arr[i].off + field_type_size;
3845
3846 rec->field_mask |= info_arr[i].type;
3847 rec->fields[i].offset = info_arr[i].off;
3848 rec->fields[i].type = info_arr[i].type;
3849 rec->fields[i].size = field_type_size;
3850
3851 switch (info_arr[i].type) {
3852 case BPF_SPIN_LOCK:
3853 WARN_ON_ONCE(rec->spin_lock_off >= 0);
3854 /* Cache offset for faster lookup at runtime */
3855 rec->spin_lock_off = rec->fields[i].offset;
3856 break;
3857 case BPF_TIMER:
3858 WARN_ON_ONCE(rec->timer_off >= 0);
3859 /* Cache offset for faster lookup at runtime */
3860 rec->timer_off = rec->fields[i].offset;
3861 break;
3862 case BPF_WORKQUEUE:
3863 WARN_ON_ONCE(rec->wq_off >= 0);
3864 /* Cache offset for faster lookup at runtime */
3865 rec->wq_off = rec->fields[i].offset;
3866 break;
3867 case BPF_REFCOUNT:
3868 WARN_ON_ONCE(rec->refcount_off >= 0);
3869 /* Cache offset for faster lookup at runtime */
3870 rec->refcount_off = rec->fields[i].offset;
3871 break;
3872 case BPF_KPTR_UNREF:
3873 case BPF_KPTR_REF:
3874 case BPF_KPTR_PERCPU:
3875 ret = btf_parse_kptr(btf, &rec->fields[i], &info_arr[i]);
3876 if (ret < 0)
3877 goto end;
3878 break;
3879 case BPF_LIST_HEAD:
3880 ret = btf_parse_list_head(btf, &rec->fields[i], &info_arr[i]);
3881 if (ret < 0)
3882 goto end;
3883 break;
3884 case BPF_RB_ROOT:
3885 ret = btf_parse_rb_root(btf, &rec->fields[i], &info_arr[i]);
3886 if (ret < 0)
3887 goto end;
3888 break;
3889 case BPF_LIST_NODE:
3890 case BPF_RB_NODE:
3891 break;
3892 default:
3893 ret = -EFAULT;
3894 goto end;
3895 }
3896 rec->cnt++;
3897 }
3898
3899 /* bpf_{list_head, rb_node} require bpf_spin_lock */
3900 if ((btf_record_has_field(rec, BPF_LIST_HEAD) ||
3901 btf_record_has_field(rec, BPF_RB_ROOT)) && rec->spin_lock_off < 0) {
3902 ret = -EINVAL;
3903 goto end;
3904 }
3905
3906 if (rec->refcount_off < 0 &&
3907 btf_record_has_field(rec, BPF_LIST_NODE) &&
3908 btf_record_has_field(rec, BPF_RB_NODE)) {
3909 ret = -EINVAL;
3910 goto end;
3911 }
3912
3913 sort_r(rec->fields, rec->cnt, sizeof(struct btf_field), btf_field_cmp,
3914 NULL, rec);
3915
3916 return rec;
3917 end:
3918 btf_record_free(rec);
3919 return ERR_PTR(ret);
3920 }
3921
btf_check_and_fixup_fields(const struct btf * btf,struct btf_record * rec)3922 int btf_check_and_fixup_fields(const struct btf *btf, struct btf_record *rec)
3923 {
3924 int i;
3925
3926 /* There are three types that signify ownership of some other type:
3927 * kptr_ref, bpf_list_head, bpf_rb_root.
3928 * kptr_ref only supports storing kernel types, which can't store
3929 * references to program allocated local types.
3930 *
3931 * Hence we only need to ensure that bpf_{list_head,rb_root} ownership
3932 * does not form cycles.
3933 */
3934 if (IS_ERR_OR_NULL(rec) || !(rec->field_mask & BPF_GRAPH_ROOT))
3935 return 0;
3936 for (i = 0; i < rec->cnt; i++) {
3937 struct btf_struct_meta *meta;
3938 u32 btf_id;
3939
3940 if (!(rec->fields[i].type & BPF_GRAPH_ROOT))
3941 continue;
3942 btf_id = rec->fields[i].graph_root.value_btf_id;
3943 meta = btf_find_struct_meta(btf, btf_id);
3944 if (!meta)
3945 return -EFAULT;
3946 rec->fields[i].graph_root.value_rec = meta->record;
3947
3948 /* We need to set value_rec for all root types, but no need
3949 * to check ownership cycle for a type unless it's also a
3950 * node type.
3951 */
3952 if (!(rec->field_mask & BPF_GRAPH_NODE))
3953 continue;
3954
3955 /* We need to ensure ownership acyclicity among all types. The
3956 * proper way to do it would be to topologically sort all BTF
3957 * IDs based on the ownership edges, since there can be multiple
3958 * bpf_{list_head,rb_node} in a type. Instead, we use the
3959 * following resaoning:
3960 *
3961 * - A type can only be owned by another type in user BTF if it
3962 * has a bpf_{list,rb}_node. Let's call these node types.
3963 * - A type can only _own_ another type in user BTF if it has a
3964 * bpf_{list_head,rb_root}. Let's call these root types.
3965 *
3966 * We ensure that if a type is both a root and node, its
3967 * element types cannot be root types.
3968 *
3969 * To ensure acyclicity:
3970 *
3971 * When A is an root type but not a node, its ownership
3972 * chain can be:
3973 * A -> B -> C
3974 * Where:
3975 * - A is an root, e.g. has bpf_rb_root.
3976 * - B is both a root and node, e.g. has bpf_rb_node and
3977 * bpf_list_head.
3978 * - C is only an root, e.g. has bpf_list_node
3979 *
3980 * When A is both a root and node, some other type already
3981 * owns it in the BTF domain, hence it can not own
3982 * another root type through any of the ownership edges.
3983 * A -> B
3984 * Where:
3985 * - A is both an root and node.
3986 * - B is only an node.
3987 */
3988 if (meta->record->field_mask & BPF_GRAPH_ROOT)
3989 return -ELOOP;
3990 }
3991 return 0;
3992 }
3993
__btf_struct_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)3994 static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
3995 u32 type_id, void *data, u8 bits_offset,
3996 struct btf_show *show)
3997 {
3998 const struct btf_member *member;
3999 void *safe_data;
4000 u32 i;
4001
4002 safe_data = btf_show_start_struct_type(show, t, type_id, data);
4003 if (!safe_data)
4004 return;
4005
4006 for_each_member(i, t, member) {
4007 const struct btf_type *member_type = btf_type_by_id(btf,
4008 member->type);
4009 const struct btf_kind_operations *ops;
4010 u32 member_offset, bitfield_size;
4011 u32 bytes_offset;
4012 u8 bits8_offset;
4013
4014 btf_show_start_member(show, member);
4015
4016 member_offset = __btf_member_bit_offset(t, member);
4017 bitfield_size = __btf_member_bitfield_size(t, member);
4018 bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
4019 bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
4020 if (bitfield_size) {
4021 safe_data = btf_show_start_type(show, member_type,
4022 member->type,
4023 data + bytes_offset);
4024 if (safe_data)
4025 btf_bitfield_show(safe_data,
4026 bits8_offset,
4027 bitfield_size, show);
4028 btf_show_end_type(show);
4029 } else {
4030 ops = btf_type_ops(member_type);
4031 ops->show(btf, member_type, member->type,
4032 data + bytes_offset, bits8_offset, show);
4033 }
4034
4035 btf_show_end_member(show);
4036 }
4037
4038 btf_show_end_struct_type(show);
4039 }
4040
btf_struct_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)4041 static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
4042 u32 type_id, void *data, u8 bits_offset,
4043 struct btf_show *show)
4044 {
4045 const struct btf_member *m = show->state.member;
4046
4047 /*
4048 * First check if any members would be shown (are non-zero).
4049 * See comments above "struct btf_show" definition for more
4050 * details on how this works at a high-level.
4051 */
4052 if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
4053 if (!show->state.depth_check) {
4054 show->state.depth_check = show->state.depth + 1;
4055 show->state.depth_to_show = 0;
4056 }
4057 __btf_struct_show(btf, t, type_id, data, bits_offset, show);
4058 /* Restore saved member data here */
4059 show->state.member = m;
4060 if (show->state.depth_check != show->state.depth + 1)
4061 return;
4062 show->state.depth_check = 0;
4063
4064 if (show->state.depth_to_show <= show->state.depth)
4065 return;
4066 /*
4067 * Reaching here indicates we have recursed and found
4068 * non-zero child values.
4069 */
4070 }
4071
4072 __btf_struct_show(btf, t, type_id, data, bits_offset, show);
4073 }
4074
4075 static struct btf_kind_operations struct_ops = {
4076 .check_meta = btf_struct_check_meta,
4077 .resolve = btf_struct_resolve,
4078 .check_member = btf_struct_check_member,
4079 .check_kflag_member = btf_generic_check_kflag_member,
4080 .log_details = btf_struct_log,
4081 .show = btf_struct_show,
4082 };
4083
btf_enum_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)4084 static int btf_enum_check_member(struct btf_verifier_env *env,
4085 const struct btf_type *struct_type,
4086 const struct btf_member *member,
4087 const struct btf_type *member_type)
4088 {
4089 u32 struct_bits_off = member->offset;
4090 u32 struct_size, bytes_offset;
4091
4092 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
4093 btf_verifier_log_member(env, struct_type, member,
4094 "Member is not byte aligned");
4095 return -EINVAL;
4096 }
4097
4098 struct_size = struct_type->size;
4099 bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
4100 if (struct_size - bytes_offset < member_type->size) {
4101 btf_verifier_log_member(env, struct_type, member,
4102 "Member exceeds struct_size");
4103 return -EINVAL;
4104 }
4105
4106 return 0;
4107 }
4108
btf_enum_check_kflag_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)4109 static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
4110 const struct btf_type *struct_type,
4111 const struct btf_member *member,
4112 const struct btf_type *member_type)
4113 {
4114 u32 struct_bits_off, nr_bits, bytes_end, struct_size;
4115 u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;
4116
4117 struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
4118 nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
4119 if (!nr_bits) {
4120 if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
4121 btf_verifier_log_member(env, struct_type, member,
4122 "Member is not byte aligned");
4123 return -EINVAL;
4124 }
4125
4126 nr_bits = int_bitsize;
4127 } else if (nr_bits > int_bitsize) {
4128 btf_verifier_log_member(env, struct_type, member,
4129 "Invalid member bitfield_size");
4130 return -EINVAL;
4131 }
4132
4133 struct_size = struct_type->size;
4134 bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
4135 if (struct_size < bytes_end) {
4136 btf_verifier_log_member(env, struct_type, member,
4137 "Member exceeds struct_size");
4138 return -EINVAL;
4139 }
4140
4141 return 0;
4142 }
4143
btf_enum_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4144 static s32 btf_enum_check_meta(struct btf_verifier_env *env,
4145 const struct btf_type *t,
4146 u32 meta_left)
4147 {
4148 const struct btf_enum *enums = btf_type_enum(t);
4149 struct btf *btf = env->btf;
4150 const char *fmt_str;
4151 u16 i, nr_enums;
4152 u32 meta_needed;
4153
4154 nr_enums = btf_type_vlen(t);
4155 meta_needed = nr_enums * sizeof(*enums);
4156
4157 if (meta_left < meta_needed) {
4158 btf_verifier_log_basic(env, t,
4159 "meta_left:%u meta_needed:%u",
4160 meta_left, meta_needed);
4161 return -EINVAL;
4162 }
4163
4164 if (t->size > 8 || !is_power_of_2(t->size)) {
4165 btf_verifier_log_type(env, t, "Unexpected size");
4166 return -EINVAL;
4167 }
4168
4169 /* enum type either no name or a valid one */
4170 if (t->name_off &&
4171 !btf_name_valid_identifier(env->btf, t->name_off)) {
4172 btf_verifier_log_type(env, t, "Invalid name");
4173 return -EINVAL;
4174 }
4175
4176 btf_verifier_log_type(env, t, NULL);
4177
4178 for (i = 0; i < nr_enums; i++) {
4179 if (!btf_name_offset_valid(btf, enums[i].name_off)) {
4180 btf_verifier_log(env, "\tInvalid name_offset:%u",
4181 enums[i].name_off);
4182 return -EINVAL;
4183 }
4184
4185 /* enum member must have a valid name */
4186 if (!enums[i].name_off ||
4187 !btf_name_valid_identifier(btf, enums[i].name_off)) {
4188 btf_verifier_log_type(env, t, "Invalid name");
4189 return -EINVAL;
4190 }
4191
4192 if (env->log.level == BPF_LOG_KERNEL)
4193 continue;
4194 fmt_str = btf_type_kflag(t) ? "\t%s val=%d\n" : "\t%s val=%u\n";
4195 btf_verifier_log(env, fmt_str,
4196 __btf_name_by_offset(btf, enums[i].name_off),
4197 enums[i].val);
4198 }
4199
4200 return meta_needed;
4201 }
4202
btf_enum_log(struct btf_verifier_env * env,const struct btf_type * t)4203 static void btf_enum_log(struct btf_verifier_env *env,
4204 const struct btf_type *t)
4205 {
4206 btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
4207 }
4208
btf_enum_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)4209 static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
4210 u32 type_id, void *data, u8 bits_offset,
4211 struct btf_show *show)
4212 {
4213 const struct btf_enum *enums = btf_type_enum(t);
4214 u32 i, nr_enums = btf_type_vlen(t);
4215 void *safe_data;
4216 int v;
4217
4218 safe_data = btf_show_start_type(show, t, type_id, data);
4219 if (!safe_data)
4220 return;
4221
4222 v = *(int *)safe_data;
4223
4224 for (i = 0; i < nr_enums; i++) {
4225 if (v != enums[i].val)
4226 continue;
4227
4228 btf_show_type_value(show, "%s",
4229 __btf_name_by_offset(btf,
4230 enums[i].name_off));
4231
4232 btf_show_end_type(show);
4233 return;
4234 }
4235
4236 if (btf_type_kflag(t))
4237 btf_show_type_value(show, "%d", v);
4238 else
4239 btf_show_type_value(show, "%u", v);
4240 btf_show_end_type(show);
4241 }
4242
4243 static struct btf_kind_operations enum_ops = {
4244 .check_meta = btf_enum_check_meta,
4245 .resolve = btf_df_resolve,
4246 .check_member = btf_enum_check_member,
4247 .check_kflag_member = btf_enum_check_kflag_member,
4248 .log_details = btf_enum_log,
4249 .show = btf_enum_show,
4250 };
4251
btf_enum64_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4252 static s32 btf_enum64_check_meta(struct btf_verifier_env *env,
4253 const struct btf_type *t,
4254 u32 meta_left)
4255 {
4256 const struct btf_enum64 *enums = btf_type_enum64(t);
4257 struct btf *btf = env->btf;
4258 const char *fmt_str;
4259 u16 i, nr_enums;
4260 u32 meta_needed;
4261
4262 nr_enums = btf_type_vlen(t);
4263 meta_needed = nr_enums * sizeof(*enums);
4264
4265 if (meta_left < meta_needed) {
4266 btf_verifier_log_basic(env, t,
4267 "meta_left:%u meta_needed:%u",
4268 meta_left, meta_needed);
4269 return -EINVAL;
4270 }
4271
4272 if (t->size > 8 || !is_power_of_2(t->size)) {
4273 btf_verifier_log_type(env, t, "Unexpected size");
4274 return -EINVAL;
4275 }
4276
4277 /* enum type either no name or a valid one */
4278 if (t->name_off &&
4279 !btf_name_valid_identifier(env->btf, t->name_off)) {
4280 btf_verifier_log_type(env, t, "Invalid name");
4281 return -EINVAL;
4282 }
4283
4284 btf_verifier_log_type(env, t, NULL);
4285
4286 for (i = 0; i < nr_enums; i++) {
4287 if (!btf_name_offset_valid(btf, enums[i].name_off)) {
4288 btf_verifier_log(env, "\tInvalid name_offset:%u",
4289 enums[i].name_off);
4290 return -EINVAL;
4291 }
4292
4293 /* enum member must have a valid name */
4294 if (!enums[i].name_off ||
4295 !btf_name_valid_identifier(btf, enums[i].name_off)) {
4296 btf_verifier_log_type(env, t, "Invalid name");
4297 return -EINVAL;
4298 }
4299
4300 if (env->log.level == BPF_LOG_KERNEL)
4301 continue;
4302
4303 fmt_str = btf_type_kflag(t) ? "\t%s val=%lld\n" : "\t%s val=%llu\n";
4304 btf_verifier_log(env, fmt_str,
4305 __btf_name_by_offset(btf, enums[i].name_off),
4306 btf_enum64_value(enums + i));
4307 }
4308
4309 return meta_needed;
4310 }
4311
btf_enum64_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)4312 static void btf_enum64_show(const struct btf *btf, const struct btf_type *t,
4313 u32 type_id, void *data, u8 bits_offset,
4314 struct btf_show *show)
4315 {
4316 const struct btf_enum64 *enums = btf_type_enum64(t);
4317 u32 i, nr_enums = btf_type_vlen(t);
4318 void *safe_data;
4319 s64 v;
4320
4321 safe_data = btf_show_start_type(show, t, type_id, data);
4322 if (!safe_data)
4323 return;
4324
4325 v = *(u64 *)safe_data;
4326
4327 for (i = 0; i < nr_enums; i++) {
4328 if (v != btf_enum64_value(enums + i))
4329 continue;
4330
4331 btf_show_type_value(show, "%s",
4332 __btf_name_by_offset(btf,
4333 enums[i].name_off));
4334
4335 btf_show_end_type(show);
4336 return;
4337 }
4338
4339 if (btf_type_kflag(t))
4340 btf_show_type_value(show, "%lld", v);
4341 else
4342 btf_show_type_value(show, "%llu", v);
4343 btf_show_end_type(show);
4344 }
4345
4346 static struct btf_kind_operations enum64_ops = {
4347 .check_meta = btf_enum64_check_meta,
4348 .resolve = btf_df_resolve,
4349 .check_member = btf_enum_check_member,
4350 .check_kflag_member = btf_enum_check_kflag_member,
4351 .log_details = btf_enum_log,
4352 .show = btf_enum64_show,
4353 };
4354
btf_func_proto_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4355 static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
4356 const struct btf_type *t,
4357 u32 meta_left)
4358 {
4359 u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);
4360
4361 if (meta_left < meta_needed) {
4362 btf_verifier_log_basic(env, t,
4363 "meta_left:%u meta_needed:%u",
4364 meta_left, meta_needed);
4365 return -EINVAL;
4366 }
4367
4368 if (t->name_off) {
4369 btf_verifier_log_type(env, t, "Invalid name");
4370 return -EINVAL;
4371 }
4372
4373 if (btf_type_kflag(t)) {
4374 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4375 return -EINVAL;
4376 }
4377
4378 btf_verifier_log_type(env, t, NULL);
4379
4380 return meta_needed;
4381 }
4382
btf_func_proto_log(struct btf_verifier_env * env,const struct btf_type * t)4383 static void btf_func_proto_log(struct btf_verifier_env *env,
4384 const struct btf_type *t)
4385 {
4386 const struct btf_param *args = (const struct btf_param *)(t + 1);
4387 u16 nr_args = btf_type_vlen(t), i;
4388
4389 btf_verifier_log(env, "return=%u args=(", t->type);
4390 if (!nr_args) {
4391 btf_verifier_log(env, "void");
4392 goto done;
4393 }
4394
4395 if (nr_args == 1 && !args[0].type) {
4396 /* Only one vararg */
4397 btf_verifier_log(env, "vararg");
4398 goto done;
4399 }
4400
4401 btf_verifier_log(env, "%u %s", args[0].type,
4402 __btf_name_by_offset(env->btf,
4403 args[0].name_off));
4404 for (i = 1; i < nr_args - 1; i++)
4405 btf_verifier_log(env, ", %u %s", args[i].type,
4406 __btf_name_by_offset(env->btf,
4407 args[i].name_off));
4408
4409 if (nr_args > 1) {
4410 const struct btf_param *last_arg = &args[nr_args - 1];
4411
4412 if (last_arg->type)
4413 btf_verifier_log(env, ", %u %s", last_arg->type,
4414 __btf_name_by_offset(env->btf,
4415 last_arg->name_off));
4416 else
4417 btf_verifier_log(env, ", vararg");
4418 }
4419
4420 done:
4421 btf_verifier_log(env, ")");
4422 }
4423
4424 static struct btf_kind_operations func_proto_ops = {
4425 .check_meta = btf_func_proto_check_meta,
4426 .resolve = btf_df_resolve,
4427 /*
4428 * BTF_KIND_FUNC_PROTO cannot be directly referred by
4429 * a struct's member.
4430 *
4431 * It should be a function pointer instead.
4432 * (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
4433 *
4434 * Hence, there is no btf_func_check_member().
4435 */
4436 .check_member = btf_df_check_member,
4437 .check_kflag_member = btf_df_check_kflag_member,
4438 .log_details = btf_func_proto_log,
4439 .show = btf_df_show,
4440 };
4441
btf_func_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4442 static s32 btf_func_check_meta(struct btf_verifier_env *env,
4443 const struct btf_type *t,
4444 u32 meta_left)
4445 {
4446 if (!t->name_off ||
4447 !btf_name_valid_identifier(env->btf, t->name_off)) {
4448 btf_verifier_log_type(env, t, "Invalid name");
4449 return -EINVAL;
4450 }
4451
4452 if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
4453 btf_verifier_log_type(env, t, "Invalid func linkage");
4454 return -EINVAL;
4455 }
4456
4457 if (btf_type_kflag(t)) {
4458 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4459 return -EINVAL;
4460 }
4461
4462 btf_verifier_log_type(env, t, NULL);
4463
4464 return 0;
4465 }
4466
btf_func_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)4467 static int btf_func_resolve(struct btf_verifier_env *env,
4468 const struct resolve_vertex *v)
4469 {
4470 const struct btf_type *t = v->t;
4471 u32 next_type_id = t->type;
4472 int err;
4473
4474 err = btf_func_check(env, t);
4475 if (err)
4476 return err;
4477
4478 env_stack_pop_resolved(env, next_type_id, 0);
4479 return 0;
4480 }
4481
4482 static struct btf_kind_operations func_ops = {
4483 .check_meta = btf_func_check_meta,
4484 .resolve = btf_func_resolve,
4485 .check_member = btf_df_check_member,
4486 .check_kflag_member = btf_df_check_kflag_member,
4487 .log_details = btf_ref_type_log,
4488 .show = btf_df_show,
4489 };
4490
btf_var_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4491 static s32 btf_var_check_meta(struct btf_verifier_env *env,
4492 const struct btf_type *t,
4493 u32 meta_left)
4494 {
4495 const struct btf_var *var;
4496 u32 meta_needed = sizeof(*var);
4497
4498 if (meta_left < meta_needed) {
4499 btf_verifier_log_basic(env, t,
4500 "meta_left:%u meta_needed:%u",
4501 meta_left, meta_needed);
4502 return -EINVAL;
4503 }
4504
4505 if (btf_type_vlen(t)) {
4506 btf_verifier_log_type(env, t, "vlen != 0");
4507 return -EINVAL;
4508 }
4509
4510 if (btf_type_kflag(t)) {
4511 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4512 return -EINVAL;
4513 }
4514
4515 if (!t->name_off ||
4516 !__btf_name_valid(env->btf, t->name_off)) {
4517 btf_verifier_log_type(env, t, "Invalid name");
4518 return -EINVAL;
4519 }
4520
4521 /* A var cannot be in type void */
4522 if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
4523 btf_verifier_log_type(env, t, "Invalid type_id");
4524 return -EINVAL;
4525 }
4526
4527 var = btf_type_var(t);
4528 if (var->linkage != BTF_VAR_STATIC &&
4529 var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
4530 btf_verifier_log_type(env, t, "Linkage not supported");
4531 return -EINVAL;
4532 }
4533
4534 btf_verifier_log_type(env, t, NULL);
4535
4536 return meta_needed;
4537 }
4538
btf_var_log(struct btf_verifier_env * env,const struct btf_type * t)4539 static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
4540 {
4541 const struct btf_var *var = btf_type_var(t);
4542
4543 btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
4544 }
4545
4546 static const struct btf_kind_operations var_ops = {
4547 .check_meta = btf_var_check_meta,
4548 .resolve = btf_var_resolve,
4549 .check_member = btf_df_check_member,
4550 .check_kflag_member = btf_df_check_kflag_member,
4551 .log_details = btf_var_log,
4552 .show = btf_var_show,
4553 };
4554
btf_datasec_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4555 static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
4556 const struct btf_type *t,
4557 u32 meta_left)
4558 {
4559 const struct btf_var_secinfo *vsi;
4560 u64 last_vsi_end_off = 0, sum = 0;
4561 u32 i, meta_needed;
4562
4563 meta_needed = btf_type_vlen(t) * sizeof(*vsi);
4564 if (meta_left < meta_needed) {
4565 btf_verifier_log_basic(env, t,
4566 "meta_left:%u meta_needed:%u",
4567 meta_left, meta_needed);
4568 return -EINVAL;
4569 }
4570
4571 if (!t->size) {
4572 btf_verifier_log_type(env, t, "size == 0");
4573 return -EINVAL;
4574 }
4575
4576 if (btf_type_kflag(t)) {
4577 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4578 return -EINVAL;
4579 }
4580
4581 if (!t->name_off ||
4582 !btf_name_valid_section(env->btf, t->name_off)) {
4583 btf_verifier_log_type(env, t, "Invalid name");
4584 return -EINVAL;
4585 }
4586
4587 btf_verifier_log_type(env, t, NULL);
4588
4589 for_each_vsi(i, t, vsi) {
4590 /* A var cannot be in type void */
4591 if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
4592 btf_verifier_log_vsi(env, t, vsi,
4593 "Invalid type_id");
4594 return -EINVAL;
4595 }
4596
4597 if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
4598 btf_verifier_log_vsi(env, t, vsi,
4599 "Invalid offset");
4600 return -EINVAL;
4601 }
4602
4603 if (!vsi->size || vsi->size > t->size) {
4604 btf_verifier_log_vsi(env, t, vsi,
4605 "Invalid size");
4606 return -EINVAL;
4607 }
4608
4609 last_vsi_end_off = vsi->offset + vsi->size;
4610 if (last_vsi_end_off > t->size) {
4611 btf_verifier_log_vsi(env, t, vsi,
4612 "Invalid offset+size");
4613 return -EINVAL;
4614 }
4615
4616 btf_verifier_log_vsi(env, t, vsi, NULL);
4617 sum += vsi->size;
4618 }
4619
4620 if (t->size < sum) {
4621 btf_verifier_log_type(env, t, "Invalid btf_info size");
4622 return -EINVAL;
4623 }
4624
4625 return meta_needed;
4626 }
4627
btf_datasec_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)4628 static int btf_datasec_resolve(struct btf_verifier_env *env,
4629 const struct resolve_vertex *v)
4630 {
4631 const struct btf_var_secinfo *vsi;
4632 struct btf *btf = env->btf;
4633 u16 i;
4634
4635 env->resolve_mode = RESOLVE_TBD;
4636 for_each_vsi_from(i, v->next_member, v->t, vsi) {
4637 u32 var_type_id = vsi->type, type_id, type_size = 0;
4638 const struct btf_type *var_type = btf_type_by_id(env->btf,
4639 var_type_id);
4640 if (!var_type || !btf_type_is_var(var_type)) {
4641 btf_verifier_log_vsi(env, v->t, vsi,
4642 "Not a VAR kind member");
4643 return -EINVAL;
4644 }
4645
4646 if (!env_type_is_resolve_sink(env, var_type) &&
4647 !env_type_is_resolved(env, var_type_id)) {
4648 env_stack_set_next_member(env, i + 1);
4649 return env_stack_push(env, var_type, var_type_id);
4650 }
4651
4652 type_id = var_type->type;
4653 if (!btf_type_id_size(btf, &type_id, &type_size)) {
4654 btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
4655 return -EINVAL;
4656 }
4657
4658 if (vsi->size < type_size) {
4659 btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
4660 return -EINVAL;
4661 }
4662 }
4663
4664 env_stack_pop_resolved(env, 0, 0);
4665 return 0;
4666 }
4667
btf_datasec_log(struct btf_verifier_env * env,const struct btf_type * t)4668 static void btf_datasec_log(struct btf_verifier_env *env,
4669 const struct btf_type *t)
4670 {
4671 btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
4672 }
4673
btf_datasec_show(const struct btf * btf,const struct btf_type * t,u32 type_id,void * data,u8 bits_offset,struct btf_show * show)4674 static void btf_datasec_show(const struct btf *btf,
4675 const struct btf_type *t, u32 type_id,
4676 void *data, u8 bits_offset,
4677 struct btf_show *show)
4678 {
4679 const struct btf_var_secinfo *vsi;
4680 const struct btf_type *var;
4681 u32 i;
4682
4683 if (!btf_show_start_type(show, t, type_id, data))
4684 return;
4685
4686 btf_show_type_value(show, "section (\"%s\") = {",
4687 __btf_name_by_offset(btf, t->name_off));
4688 for_each_vsi(i, t, vsi) {
4689 var = btf_type_by_id(btf, vsi->type);
4690 if (i)
4691 btf_show(show, ",");
4692 btf_type_ops(var)->show(btf, var, vsi->type,
4693 data + vsi->offset, bits_offset, show);
4694 }
4695 btf_show_end_type(show);
4696 }
4697
4698 static const struct btf_kind_operations datasec_ops = {
4699 .check_meta = btf_datasec_check_meta,
4700 .resolve = btf_datasec_resolve,
4701 .check_member = btf_df_check_member,
4702 .check_kflag_member = btf_df_check_kflag_member,
4703 .log_details = btf_datasec_log,
4704 .show = btf_datasec_show,
4705 };
4706
btf_float_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4707 static s32 btf_float_check_meta(struct btf_verifier_env *env,
4708 const struct btf_type *t,
4709 u32 meta_left)
4710 {
4711 if (btf_type_vlen(t)) {
4712 btf_verifier_log_type(env, t, "vlen != 0");
4713 return -EINVAL;
4714 }
4715
4716 if (btf_type_kflag(t)) {
4717 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4718 return -EINVAL;
4719 }
4720
4721 if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
4722 t->size != 16) {
4723 btf_verifier_log_type(env, t, "Invalid type_size");
4724 return -EINVAL;
4725 }
4726
4727 btf_verifier_log_type(env, t, NULL);
4728
4729 return 0;
4730 }
4731
btf_float_check_member(struct btf_verifier_env * env,const struct btf_type * struct_type,const struct btf_member * member,const struct btf_type * member_type)4732 static int btf_float_check_member(struct btf_verifier_env *env,
4733 const struct btf_type *struct_type,
4734 const struct btf_member *member,
4735 const struct btf_type *member_type)
4736 {
4737 u64 start_offset_bytes;
4738 u64 end_offset_bytes;
4739 u64 misalign_bits;
4740 u64 align_bytes;
4741 u64 align_bits;
4742
4743 /* Different architectures have different alignment requirements, so
4744 * here we check only for the reasonable minimum. This way we ensure
4745 * that types after CO-RE can pass the kernel BTF verifier.
4746 */
4747 align_bytes = min_t(u64, sizeof(void *), member_type->size);
4748 align_bits = align_bytes * BITS_PER_BYTE;
4749 div64_u64_rem(member->offset, align_bits, &misalign_bits);
4750 if (misalign_bits) {
4751 btf_verifier_log_member(env, struct_type, member,
4752 "Member is not properly aligned");
4753 return -EINVAL;
4754 }
4755
4756 start_offset_bytes = member->offset / BITS_PER_BYTE;
4757 end_offset_bytes = start_offset_bytes + member_type->size;
4758 if (end_offset_bytes > struct_type->size) {
4759 btf_verifier_log_member(env, struct_type, member,
4760 "Member exceeds struct_size");
4761 return -EINVAL;
4762 }
4763
4764 return 0;
4765 }
4766
btf_float_log(struct btf_verifier_env * env,const struct btf_type * t)4767 static void btf_float_log(struct btf_verifier_env *env,
4768 const struct btf_type *t)
4769 {
4770 btf_verifier_log(env, "size=%u", t->size);
4771 }
4772
4773 static const struct btf_kind_operations float_ops = {
4774 .check_meta = btf_float_check_meta,
4775 .resolve = btf_df_resolve,
4776 .check_member = btf_float_check_member,
4777 .check_kflag_member = btf_generic_check_kflag_member,
4778 .log_details = btf_float_log,
4779 .show = btf_df_show,
4780 };
4781
btf_decl_tag_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)4782 static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
4783 const struct btf_type *t,
4784 u32 meta_left)
4785 {
4786 const struct btf_decl_tag *tag;
4787 u32 meta_needed = sizeof(*tag);
4788 s32 component_idx;
4789 const char *value;
4790
4791 if (meta_left < meta_needed) {
4792 btf_verifier_log_basic(env, t,
4793 "meta_left:%u meta_needed:%u",
4794 meta_left, meta_needed);
4795 return -EINVAL;
4796 }
4797
4798 value = btf_name_by_offset(env->btf, t->name_off);
4799 if (!value || !value[0]) {
4800 btf_verifier_log_type(env, t, "Invalid value");
4801 return -EINVAL;
4802 }
4803
4804 if (btf_type_vlen(t)) {
4805 btf_verifier_log_type(env, t, "vlen != 0");
4806 return -EINVAL;
4807 }
4808
4809 if (btf_type_kflag(t)) {
4810 btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
4811 return -EINVAL;
4812 }
4813
4814 component_idx = btf_type_decl_tag(t)->component_idx;
4815 if (component_idx < -1) {
4816 btf_verifier_log_type(env, t, "Invalid component_idx");
4817 return -EINVAL;
4818 }
4819
4820 btf_verifier_log_type(env, t, NULL);
4821
4822 return meta_needed;
4823 }
4824
btf_decl_tag_resolve(struct btf_verifier_env * env,const struct resolve_vertex * v)4825 static int btf_decl_tag_resolve(struct btf_verifier_env *env,
4826 const struct resolve_vertex *v)
4827 {
4828 const struct btf_type *next_type;
4829 const struct btf_type *t = v->t;
4830 u32 next_type_id = t->type;
4831 struct btf *btf = env->btf;
4832 s32 component_idx;
4833 u32 vlen;
4834
4835 next_type = btf_type_by_id(btf, next_type_id);
4836 if (!next_type || !btf_type_is_decl_tag_target(next_type)) {
4837 btf_verifier_log_type(env, v->t, "Invalid type_id");
4838 return -EINVAL;
4839 }
4840
4841 if (!env_type_is_resolve_sink(env, next_type) &&
4842 !env_type_is_resolved(env, next_type_id))
4843 return env_stack_push(env, next_type, next_type_id);
4844
4845 component_idx = btf_type_decl_tag(t)->component_idx;
4846 if (component_idx != -1) {
4847 if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
4848 btf_verifier_log_type(env, v->t, "Invalid component_idx");
4849 return -EINVAL;
4850 }
4851
4852 if (btf_type_is_struct(next_type)) {
4853 vlen = btf_type_vlen(next_type);
4854 } else {
4855 /* next_type should be a function */
4856 next_type = btf_type_by_id(btf, next_type->type);
4857 vlen = btf_type_vlen(next_type);
4858 }
4859
4860 if ((u32)component_idx >= vlen) {
4861 btf_verifier_log_type(env, v->t, "Invalid component_idx");
4862 return -EINVAL;
4863 }
4864 }
4865
4866 env_stack_pop_resolved(env, next_type_id, 0);
4867
4868 return 0;
4869 }
4870
btf_decl_tag_log(struct btf_verifier_env * env,const struct btf_type * t)4871 static void btf_decl_tag_log(struct btf_verifier_env *env, const struct btf_type *t)
4872 {
4873 btf_verifier_log(env, "type=%u component_idx=%d", t->type,
4874 btf_type_decl_tag(t)->component_idx);
4875 }
4876
4877 static const struct btf_kind_operations decl_tag_ops = {
4878 .check_meta = btf_decl_tag_check_meta,
4879 .resolve = btf_decl_tag_resolve,
4880 .check_member = btf_df_check_member,
4881 .check_kflag_member = btf_df_check_kflag_member,
4882 .log_details = btf_decl_tag_log,
4883 .show = btf_df_show,
4884 };
4885
btf_func_proto_check(struct btf_verifier_env * env,const struct btf_type * t)4886 static int btf_func_proto_check(struct btf_verifier_env *env,
4887 const struct btf_type *t)
4888 {
4889 const struct btf_type *ret_type;
4890 const struct btf_param *args;
4891 const struct btf *btf;
4892 u16 nr_args, i;
4893 int err;
4894
4895 btf = env->btf;
4896 args = (const struct btf_param *)(t + 1);
4897 nr_args = btf_type_vlen(t);
4898
4899 /* Check func return type which could be "void" (t->type == 0) */
4900 if (t->type) {
4901 u32 ret_type_id = t->type;
4902
4903 ret_type = btf_type_by_id(btf, ret_type_id);
4904 if (!ret_type) {
4905 btf_verifier_log_type(env, t, "Invalid return type");
4906 return -EINVAL;
4907 }
4908
4909 if (btf_type_is_resolve_source_only(ret_type)) {
4910 btf_verifier_log_type(env, t, "Invalid return type");
4911 return -EINVAL;
4912 }
4913
4914 if (btf_type_needs_resolve(ret_type) &&
4915 !env_type_is_resolved(env, ret_type_id)) {
4916 err = btf_resolve(env, ret_type, ret_type_id);
4917 if (err)
4918 return err;
4919 }
4920
4921 /* Ensure the return type is a type that has a size */
4922 if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
4923 btf_verifier_log_type(env, t, "Invalid return type");
4924 return -EINVAL;
4925 }
4926 }
4927
4928 if (!nr_args)
4929 return 0;
4930
4931 /* Last func arg type_id could be 0 if it is a vararg */
4932 if (!args[nr_args - 1].type) {
4933 if (args[nr_args - 1].name_off) {
4934 btf_verifier_log_type(env, t, "Invalid arg#%u",
4935 nr_args);
4936 return -EINVAL;
4937 }
4938 nr_args--;
4939 }
4940
4941 for (i = 0; i < nr_args; i++) {
4942 const struct btf_type *arg_type;
4943 u32 arg_type_id;
4944
4945 arg_type_id = args[i].type;
4946 arg_type = btf_type_by_id(btf, arg_type_id);
4947 if (!arg_type) {
4948 btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
4949 return -EINVAL;
4950 }
4951
4952 if (btf_type_is_resolve_source_only(arg_type)) {
4953 btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
4954 return -EINVAL;
4955 }
4956
4957 if (args[i].name_off &&
4958 (!btf_name_offset_valid(btf, args[i].name_off) ||
4959 !btf_name_valid_identifier(btf, args[i].name_off))) {
4960 btf_verifier_log_type(env, t,
4961 "Invalid arg#%u", i + 1);
4962 return -EINVAL;
4963 }
4964
4965 if (btf_type_needs_resolve(arg_type) &&
4966 !env_type_is_resolved(env, arg_type_id)) {
4967 err = btf_resolve(env, arg_type, arg_type_id);
4968 if (err)
4969 return err;
4970 }
4971
4972 if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
4973 btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
4974 return -EINVAL;
4975 }
4976 }
4977
4978 return 0;
4979 }
4980
btf_func_check(struct btf_verifier_env * env,const struct btf_type * t)4981 static int btf_func_check(struct btf_verifier_env *env,
4982 const struct btf_type *t)
4983 {
4984 const struct btf_type *proto_type;
4985 const struct btf_param *args;
4986 const struct btf *btf;
4987 u16 nr_args, i;
4988
4989 btf = env->btf;
4990 proto_type = btf_type_by_id(btf, t->type);
4991
4992 if (!proto_type || !btf_type_is_func_proto(proto_type)) {
4993 btf_verifier_log_type(env, t, "Invalid type_id");
4994 return -EINVAL;
4995 }
4996
4997 args = (const struct btf_param *)(proto_type + 1);
4998 nr_args = btf_type_vlen(proto_type);
4999 for (i = 0; i < nr_args; i++) {
5000 if (!args[i].name_off && args[i].type) {
5001 btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
5002 return -EINVAL;
5003 }
5004 }
5005
5006 return 0;
5007 }
5008
5009 static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
5010 [BTF_KIND_INT] = &int_ops,
5011 [BTF_KIND_PTR] = &ptr_ops,
5012 [BTF_KIND_ARRAY] = &array_ops,
5013 [BTF_KIND_STRUCT] = &struct_ops,
5014 [BTF_KIND_UNION] = &struct_ops,
5015 [BTF_KIND_ENUM] = &enum_ops,
5016 [BTF_KIND_FWD] = &fwd_ops,
5017 [BTF_KIND_TYPEDEF] = &modifier_ops,
5018 [BTF_KIND_VOLATILE] = &modifier_ops,
5019 [BTF_KIND_CONST] = &modifier_ops,
5020 [BTF_KIND_RESTRICT] = &modifier_ops,
5021 [BTF_KIND_FUNC] = &func_ops,
5022 [BTF_KIND_FUNC_PROTO] = &func_proto_ops,
5023 [BTF_KIND_VAR] = &var_ops,
5024 [BTF_KIND_DATASEC] = &datasec_ops,
5025 [BTF_KIND_FLOAT] = &float_ops,
5026 [BTF_KIND_DECL_TAG] = &decl_tag_ops,
5027 [BTF_KIND_TYPE_TAG] = &modifier_ops,
5028 [BTF_KIND_ENUM64] = &enum64_ops,
5029 };
5030
btf_check_meta(struct btf_verifier_env * env,const struct btf_type * t,u32 meta_left)5031 static s32 btf_check_meta(struct btf_verifier_env *env,
5032 const struct btf_type *t,
5033 u32 meta_left)
5034 {
5035 u32 saved_meta_left = meta_left;
5036 s32 var_meta_size;
5037
5038 if (meta_left < sizeof(*t)) {
5039 btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
5040 env->log_type_id, meta_left, sizeof(*t));
5041 return -EINVAL;
5042 }
5043 meta_left -= sizeof(*t);
5044
5045 if (t->info & ~BTF_INFO_MASK) {
5046 btf_verifier_log(env, "[%u] Invalid btf_info:%x",
5047 env->log_type_id, t->info);
5048 return -EINVAL;
5049 }
5050
5051 if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
5052 BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
5053 btf_verifier_log(env, "[%u] Invalid kind:%u",
5054 env->log_type_id, BTF_INFO_KIND(t->info));
5055 return -EINVAL;
5056 }
5057
5058 if (!btf_name_offset_valid(env->btf, t->name_off)) {
5059 btf_verifier_log(env, "[%u] Invalid name_offset:%u",
5060 env->log_type_id, t->name_off);
5061 return -EINVAL;
5062 }
5063
5064 var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
5065 if (var_meta_size < 0)
5066 return var_meta_size;
5067
5068 meta_left -= var_meta_size;
5069
5070 return saved_meta_left - meta_left;
5071 }
5072
btf_check_all_metas(struct btf_verifier_env * env)5073 static int btf_check_all_metas(struct btf_verifier_env *env)
5074 {
5075 struct btf *btf = env->btf;
5076 struct btf_header *hdr;
5077 void *cur, *end;
5078
5079 hdr = &btf->hdr;
5080 cur = btf->nohdr_data + hdr->type_off;
5081 end = cur + hdr->type_len;
5082
5083 env->log_type_id = btf->base_btf ? btf->start_id : 1;
5084 while (cur < end) {
5085 struct btf_type *t = cur;
5086 s32 meta_size;
5087
5088 meta_size = btf_check_meta(env, t, end - cur);
5089 if (meta_size < 0)
5090 return meta_size;
5091
5092 btf_add_type(env, t);
5093 cur += meta_size;
5094 env->log_type_id++;
5095 }
5096
5097 return 0;
5098 }
5099
btf_resolve_valid(struct btf_verifier_env * env,const struct btf_type * t,u32 type_id)5100 static bool btf_resolve_valid(struct btf_verifier_env *env,
5101 const struct btf_type *t,
5102 u32 type_id)
5103 {
5104 struct btf *btf = env->btf;
5105
5106 if (!env_type_is_resolved(env, type_id))
5107 return false;
5108
5109 if (btf_type_is_struct(t) || btf_type_is_datasec(t))
5110 return !btf_resolved_type_id(btf, type_id) &&
5111 !btf_resolved_type_size(btf, type_id);
5112
5113 if (btf_type_is_decl_tag(t) || btf_type_is_func(t))
5114 return btf_resolved_type_id(btf, type_id) &&
5115 !btf_resolved_type_size(btf, type_id);
5116
5117 if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
5118 btf_type_is_var(t)) {
5119 t = btf_type_id_resolve(btf, &type_id);
5120 return t &&
5121 !btf_type_is_modifier(t) &&
5122 !btf_type_is_var(t) &&
5123 !btf_type_is_datasec(t);
5124 }
5125
5126 if (btf_type_is_array(t)) {
5127 const struct btf_array *array = btf_type_array(t);
5128 const struct btf_type *elem_type;
5129 u32 elem_type_id = array->type;
5130 u32 elem_size;
5131
5132 elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
5133 return elem_type && !btf_type_is_modifier(elem_type) &&
5134 (array->nelems * elem_size ==
5135 btf_resolved_type_size(btf, type_id));
5136 }
5137
5138 return false;
5139 }
5140
btf_resolve(struct btf_verifier_env * env,const struct btf_type * t,u32 type_id)5141 static int btf_resolve(struct btf_verifier_env *env,
5142 const struct btf_type *t, u32 type_id)
5143 {
5144 u32 save_log_type_id = env->log_type_id;
5145 const struct resolve_vertex *v;
5146 int err = 0;
5147
5148 env->resolve_mode = RESOLVE_TBD;
5149 env_stack_push(env, t, type_id);
5150 while (!err && (v = env_stack_peak(env))) {
5151 env->log_type_id = v->type_id;
5152 err = btf_type_ops(v->t)->resolve(env, v);
5153 }
5154
5155 env->log_type_id = type_id;
5156 if (err == -E2BIG) {
5157 btf_verifier_log_type(env, t,
5158 "Exceeded max resolving depth:%u",
5159 MAX_RESOLVE_DEPTH);
5160 } else if (err == -EEXIST) {
5161 btf_verifier_log_type(env, t, "Loop detected");
5162 }
5163
5164 /* Final sanity check */
5165 if (!err && !btf_resolve_valid(env, t, type_id)) {
5166 btf_verifier_log_type(env, t, "Invalid resolve state");
5167 err = -EINVAL;
5168 }
5169
5170 env->log_type_id = save_log_type_id;
5171 return err;
5172 }
5173
btf_check_all_types(struct btf_verifier_env * env)5174 static int btf_check_all_types(struct btf_verifier_env *env)
5175 {
5176 struct btf *btf = env->btf;
5177 const struct btf_type *t;
5178 u32 type_id, i;
5179 int err;
5180
5181 err = env_resolve_init(env);
5182 if (err)
5183 return err;
5184
5185 env->phase++;
5186 for (i = btf->base_btf ? 0 : 1; i < btf->nr_types; i++) {
5187 type_id = btf->start_id + i;
5188 t = btf_type_by_id(btf, type_id);
5189
5190 env->log_type_id = type_id;
5191 if (btf_type_needs_resolve(t) &&
5192 !env_type_is_resolved(env, type_id)) {
5193 err = btf_resolve(env, t, type_id);
5194 if (err)
5195 return err;
5196 }
5197
5198 if (btf_type_is_func_proto(t)) {
5199 err = btf_func_proto_check(env, t);
5200 if (err)
5201 return err;
5202 }
5203 }
5204
5205 return 0;
5206 }
5207
btf_parse_type_sec(struct btf_verifier_env * env)5208 static int btf_parse_type_sec(struct btf_verifier_env *env)
5209 {
5210 const struct btf_header *hdr = &env->btf->hdr;
5211 int err;
5212
5213 /* Type section must align to 4 bytes */
5214 if (hdr->type_off & (sizeof(u32) - 1)) {
5215 btf_verifier_log(env, "Unaligned type_off");
5216 return -EINVAL;
5217 }
5218
5219 if (!env->btf->base_btf && !hdr->type_len) {
5220 btf_verifier_log(env, "No type found");
5221 return -EINVAL;
5222 }
5223
5224 err = btf_check_all_metas(env);
5225 if (err)
5226 return err;
5227
5228 return btf_check_all_types(env);
5229 }
5230
btf_parse_str_sec(struct btf_verifier_env * env)5231 static int btf_parse_str_sec(struct btf_verifier_env *env)
5232 {
5233 const struct btf_header *hdr;
5234 struct btf *btf = env->btf;
5235 const char *start, *end;
5236
5237 hdr = &btf->hdr;
5238 start = btf->nohdr_data + hdr->str_off;
5239 end = start + hdr->str_len;
5240
5241 if (end != btf->data + btf->data_size) {
5242 btf_verifier_log(env, "String section is not at the end");
5243 return -EINVAL;
5244 }
5245
5246 btf->strings = start;
5247
5248 if (btf->base_btf && !hdr->str_len)
5249 return 0;
5250 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET || end[-1]) {
5251 btf_verifier_log(env, "Invalid string section");
5252 return -EINVAL;
5253 }
5254 if (!btf->base_btf && start[0]) {
5255 btf_verifier_log(env, "Invalid string section");
5256 return -EINVAL;
5257 }
5258
5259 return 0;
5260 }
5261
5262 static const size_t btf_sec_info_offset[] = {
5263 offsetof(struct btf_header, type_off),
5264 offsetof(struct btf_header, str_off),
5265 };
5266
btf_sec_info_cmp(const void * a,const void * b)5267 static int btf_sec_info_cmp(const void *a, const void *b)
5268 {
5269 const struct btf_sec_info *x = a;
5270 const struct btf_sec_info *y = b;
5271
5272 return (int)(x->off - y->off) ? : (int)(x->len - y->len);
5273 }
5274
btf_check_sec_info(struct btf_verifier_env * env,u32 btf_data_size)5275 static int btf_check_sec_info(struct btf_verifier_env *env,
5276 u32 btf_data_size)
5277 {
5278 struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
5279 u32 total, expected_total, i;
5280 const struct btf_header *hdr;
5281 const struct btf *btf;
5282
5283 btf = env->btf;
5284 hdr = &btf->hdr;
5285
5286 /* Populate the secs from hdr */
5287 for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
5288 secs[i] = *(struct btf_sec_info *)((void *)hdr +
5289 btf_sec_info_offset[i]);
5290
5291 sort(secs, ARRAY_SIZE(btf_sec_info_offset),
5292 sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);
5293
5294 /* Check for gaps and overlap among sections */
5295 total = 0;
5296 expected_total = btf_data_size - hdr->hdr_len;
5297 for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
5298 if (expected_total < secs[i].off) {
5299 btf_verifier_log(env, "Invalid section offset");
5300 return -EINVAL;
5301 }
5302 if (total < secs[i].off) {
5303 /* gap */
5304 btf_verifier_log(env, "Unsupported section found");
5305 return -EINVAL;
5306 }
5307 if (total > secs[i].off) {
5308 btf_verifier_log(env, "Section overlap found");
5309 return -EINVAL;
5310 }
5311 if (expected_total - total < secs[i].len) {
5312 btf_verifier_log(env,
5313 "Total section length too long");
5314 return -EINVAL;
5315 }
5316 total += secs[i].len;
5317 }
5318
5319 /* There is data other than hdr and known sections */
5320 if (expected_total != total) {
5321 btf_verifier_log(env, "Unsupported section found");
5322 return -EINVAL;
5323 }
5324
5325 return 0;
5326 }
5327
btf_parse_hdr(struct btf_verifier_env * env)5328 static int btf_parse_hdr(struct btf_verifier_env *env)
5329 {
5330 u32 hdr_len, hdr_copy, btf_data_size;
5331 const struct btf_header *hdr;
5332 struct btf *btf;
5333
5334 btf = env->btf;
5335 btf_data_size = btf->data_size;
5336
5337 if (btf_data_size < offsetofend(struct btf_header, hdr_len)) {
5338 btf_verifier_log(env, "hdr_len not found");
5339 return -EINVAL;
5340 }
5341
5342 hdr = btf->data;
5343 hdr_len = hdr->hdr_len;
5344 if (btf_data_size < hdr_len) {
5345 btf_verifier_log(env, "btf_header not found");
5346 return -EINVAL;
5347 }
5348
5349 /* Ensure the unsupported header fields are zero */
5350 if (hdr_len > sizeof(btf->hdr)) {
5351 u8 *expected_zero = btf->data + sizeof(btf->hdr);
5352 u8 *end = btf->data + hdr_len;
5353
5354 for (; expected_zero < end; expected_zero++) {
5355 if (*expected_zero) {
5356 btf_verifier_log(env, "Unsupported btf_header");
5357 return -E2BIG;
5358 }
5359 }
5360 }
5361
5362 hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
5363 memcpy(&btf->hdr, btf->data, hdr_copy);
5364
5365 hdr = &btf->hdr;
5366
5367 btf_verifier_log_hdr(env, btf_data_size);
5368
5369 if (hdr->magic != BTF_MAGIC) {
5370 btf_verifier_log(env, "Invalid magic");
5371 return -EINVAL;
5372 }
5373
5374 if (hdr->version != BTF_VERSION) {
5375 btf_verifier_log(env, "Unsupported version");
5376 return -ENOTSUPP;
5377 }
5378
5379 if (hdr->flags) {
5380 btf_verifier_log(env, "Unsupported flags");
5381 return -ENOTSUPP;
5382 }
5383
5384 if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
5385 btf_verifier_log(env, "No data");
5386 return -EINVAL;
5387 }
5388
5389 return btf_check_sec_info(env, btf_data_size);
5390 }
5391
5392 static const char *alloc_obj_fields[] = {
5393 "bpf_spin_lock",
5394 "bpf_list_head",
5395 "bpf_list_node",
5396 "bpf_rb_root",
5397 "bpf_rb_node",
5398 "bpf_refcount",
5399 };
5400
5401 static struct btf_struct_metas *
btf_parse_struct_metas(struct bpf_verifier_log * log,struct btf * btf)5402 btf_parse_struct_metas(struct bpf_verifier_log *log, struct btf *btf)
5403 {
5404 union {
5405 struct btf_id_set set;
5406 struct {
5407 u32 _cnt;
5408 u32 _ids[ARRAY_SIZE(alloc_obj_fields)];
5409 } _arr;
5410 } aof;
5411 struct btf_struct_metas *tab = NULL;
5412 int i, n, id, ret;
5413
5414 BUILD_BUG_ON(offsetof(struct btf_id_set, cnt) != 0);
5415 BUILD_BUG_ON(sizeof(struct btf_id_set) != sizeof(u32));
5416
5417 memset(&aof, 0, sizeof(aof));
5418 for (i = 0; i < ARRAY_SIZE(alloc_obj_fields); i++) {
5419 /* Try to find whether this special type exists in user BTF, and
5420 * if so remember its ID so we can easily find it among members
5421 * of structs that we iterate in the next loop.
5422 */
5423 id = btf_find_by_name_kind(btf, alloc_obj_fields[i], BTF_KIND_STRUCT);
5424 if (id < 0)
5425 continue;
5426 aof.set.ids[aof.set.cnt++] = id;
5427 }
5428
5429 if (!aof.set.cnt)
5430 return NULL;
5431 sort(&aof.set.ids, aof.set.cnt, sizeof(aof.set.ids[0]), btf_id_cmp_func, NULL);
5432
5433 n = btf_nr_types(btf);
5434 for (i = 1; i < n; i++) {
5435 struct btf_struct_metas *new_tab;
5436 const struct btf_member *member;
5437 struct btf_struct_meta *type;
5438 struct btf_record *record;
5439 const struct btf_type *t;
5440 int j, tab_cnt;
5441
5442 t = btf_type_by_id(btf, i);
5443 if (!t) {
5444 ret = -EINVAL;
5445 goto free;
5446 }
5447 if (!__btf_type_is_struct(t))
5448 continue;
5449
5450 cond_resched();
5451
5452 for_each_member(j, t, member) {
5453 if (btf_id_set_contains(&aof.set, member->type))
5454 goto parse;
5455 }
5456 continue;
5457 parse:
5458 tab_cnt = tab ? tab->cnt : 0;
5459 new_tab = krealloc(tab, offsetof(struct btf_struct_metas, types[tab_cnt + 1]),
5460 GFP_KERNEL | __GFP_NOWARN);
5461 if (!new_tab) {
5462 ret = -ENOMEM;
5463 goto free;
5464 }
5465 if (!tab)
5466 new_tab->cnt = 0;
5467 tab = new_tab;
5468
5469 type = &tab->types[tab->cnt];
5470 type->btf_id = i;
5471 record = btf_parse_fields(btf, t, BPF_SPIN_LOCK | BPF_LIST_HEAD | BPF_LIST_NODE |
5472 BPF_RB_ROOT | BPF_RB_NODE | BPF_REFCOUNT, t->size);
5473 /* The record cannot be unset, treat it as an error if so */
5474 if (IS_ERR_OR_NULL(record)) {
5475 ret = PTR_ERR_OR_ZERO(record) ?: -EFAULT;
5476 goto free;
5477 }
5478 type->record = record;
5479 tab->cnt++;
5480 }
5481 return tab;
5482 free:
5483 btf_struct_metas_free(tab);
5484 return ERR_PTR(ret);
5485 }
5486
btf_find_struct_meta(const struct btf * btf,u32 btf_id)5487 struct btf_struct_meta *btf_find_struct_meta(const struct btf *btf, u32 btf_id)
5488 {
5489 struct btf_struct_metas *tab;
5490
5491 BUILD_BUG_ON(offsetof(struct btf_struct_meta, btf_id) != 0);
5492 tab = btf->struct_meta_tab;
5493 if (!tab)
5494 return NULL;
5495 return bsearch(&btf_id, tab->types, tab->cnt, sizeof(tab->types[0]), btf_id_cmp_func);
5496 }
5497
btf_check_type_tags(struct btf_verifier_env * env,struct btf * btf,int start_id)5498 static int btf_check_type_tags(struct btf_verifier_env *env,
5499 struct btf *btf, int start_id)
5500 {
5501 int i, n, good_id = start_id - 1;
5502 bool in_tags;
5503
5504 n = btf_nr_types(btf);
5505 for (i = start_id; i < n; i++) {
5506 const struct btf_type *t;
5507 int chain_limit = 32;
5508 u32 cur_id = i;
5509
5510 t = btf_type_by_id(btf, i);
5511 if (!t)
5512 return -EINVAL;
5513 if (!btf_type_is_modifier(t))
5514 continue;
5515
5516 cond_resched();
5517
5518 in_tags = btf_type_is_type_tag(t);
5519 while (btf_type_is_modifier(t)) {
5520 if (!chain_limit--) {
5521 btf_verifier_log(env, "Max chain length or cycle detected");
5522 return -ELOOP;
5523 }
5524 if (btf_type_is_type_tag(t)) {
5525 if (!in_tags) {
5526 btf_verifier_log(env, "Type tags don't precede modifiers");
5527 return -EINVAL;
5528 }
5529 } else if (in_tags) {
5530 in_tags = false;
5531 }
5532 if (cur_id <= good_id)
5533 break;
5534 /* Move to next type */
5535 cur_id = t->type;
5536 t = btf_type_by_id(btf, cur_id);
5537 if (!t)
5538 return -EINVAL;
5539 }
5540 good_id = i;
5541 }
5542 return 0;
5543 }
5544
finalize_log(struct bpf_verifier_log * log,bpfptr_t uattr,u32 uattr_size)5545 static int finalize_log(struct bpf_verifier_log *log, bpfptr_t uattr, u32 uattr_size)
5546 {
5547 u32 log_true_size;
5548 int err;
5549
5550 err = bpf_vlog_finalize(log, &log_true_size);
5551
5552 if (uattr_size >= offsetofend(union bpf_attr, btf_log_true_size) &&
5553 copy_to_bpfptr_offset(uattr, offsetof(union bpf_attr, btf_log_true_size),
5554 &log_true_size, sizeof(log_true_size)))
5555 err = -EFAULT;
5556
5557 return err;
5558 }
5559
btf_parse(const union bpf_attr * attr,bpfptr_t uattr,u32 uattr_size)5560 static struct btf *btf_parse(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
5561 {
5562 bpfptr_t btf_data = make_bpfptr(attr->btf, uattr.is_kernel);
5563 char __user *log_ubuf = u64_to_user_ptr(attr->btf_log_buf);
5564 struct btf_struct_metas *struct_meta_tab;
5565 struct btf_verifier_env *env = NULL;
5566 struct btf *btf = NULL;
5567 u8 *data;
5568 int err, ret;
5569
5570 if (attr->btf_size > BTF_MAX_SIZE)
5571 return ERR_PTR(-E2BIG);
5572
5573 env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
5574 if (!env)
5575 return ERR_PTR(-ENOMEM);
5576
5577 /* user could have requested verbose verifier output
5578 * and supplied buffer to store the verification trace
5579 */
5580 err = bpf_vlog_init(&env->log, attr->btf_log_level,
5581 log_ubuf, attr->btf_log_size);
5582 if (err)
5583 goto errout_free;
5584
5585 btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
5586 if (!btf) {
5587 err = -ENOMEM;
5588 goto errout;
5589 }
5590 env->btf = btf;
5591
5592 data = kvmalloc(attr->btf_size, GFP_KERNEL | __GFP_NOWARN);
5593 if (!data) {
5594 err = -ENOMEM;
5595 goto errout;
5596 }
5597
5598 btf->data = data;
5599 btf->data_size = attr->btf_size;
5600
5601 if (copy_from_bpfptr(data, btf_data, attr->btf_size)) {
5602 err = -EFAULT;
5603 goto errout;
5604 }
5605
5606 err = btf_parse_hdr(env);
5607 if (err)
5608 goto errout;
5609
5610 btf->nohdr_data = btf->data + btf->hdr.hdr_len;
5611
5612 err = btf_parse_str_sec(env);
5613 if (err)
5614 goto errout;
5615
5616 err = btf_parse_type_sec(env);
5617 if (err)
5618 goto errout;
5619
5620 err = btf_check_type_tags(env, btf, 1);
5621 if (err)
5622 goto errout;
5623
5624 struct_meta_tab = btf_parse_struct_metas(&env->log, btf);
5625 if (IS_ERR(struct_meta_tab)) {
5626 err = PTR_ERR(struct_meta_tab);
5627 goto errout;
5628 }
5629 btf->struct_meta_tab = struct_meta_tab;
5630
5631 if (struct_meta_tab) {
5632 int i;
5633
5634 for (i = 0; i < struct_meta_tab->cnt; i++) {
5635 err = btf_check_and_fixup_fields(btf, struct_meta_tab->types[i].record);
5636 if (err < 0)
5637 goto errout_meta;
5638 }
5639 }
5640
5641 err = finalize_log(&env->log, uattr, uattr_size);
5642 if (err)
5643 goto errout_free;
5644
5645 btf_verifier_env_free(env);
5646 refcount_set(&btf->refcnt, 1);
5647 return btf;
5648
5649 errout_meta:
5650 btf_free_struct_meta_tab(btf);
5651 errout:
5652 /* overwrite err with -ENOSPC or -EFAULT */
5653 ret = finalize_log(&env->log, uattr, uattr_size);
5654 if (ret)
5655 err = ret;
5656 errout_free:
5657 btf_verifier_env_free(env);
5658 if (btf)
5659 btf_free(btf);
5660 return ERR_PTR(err);
5661 }
5662
5663 extern char __start_BTF[];
5664 extern char __stop_BTF[];
5665 extern struct btf *btf_vmlinux;
5666
5667 #define BPF_MAP_TYPE(_id, _ops)
5668 #define BPF_LINK_TYPE(_id, _name)
5669 static union {
5670 struct bpf_ctx_convert {
5671 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
5672 prog_ctx_type _id##_prog; \
5673 kern_ctx_type _id##_kern;
5674 #include <linux/bpf_types.h>
5675 #undef BPF_PROG_TYPE
5676 } *__t;
5677 /* 't' is written once under lock. Read many times. */
5678 const struct btf_type *t;
5679 } bpf_ctx_convert;
5680 enum {
5681 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
5682 __ctx_convert##_id,
5683 #include <linux/bpf_types.h>
5684 #undef BPF_PROG_TYPE
5685 __ctx_convert_unused, /* to avoid empty enum in extreme .config */
5686 };
5687 static u8 bpf_ctx_convert_map[] = {
5688 #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
5689 [_id] = __ctx_convert##_id,
5690 #include <linux/bpf_types.h>
5691 #undef BPF_PROG_TYPE
5692 0, /* avoid empty array */
5693 };
5694 #undef BPF_MAP_TYPE
5695 #undef BPF_LINK_TYPE
5696
find_canonical_prog_ctx_type(enum bpf_prog_type prog_type)5697 static const struct btf_type *find_canonical_prog_ctx_type(enum bpf_prog_type prog_type)
5698 {
5699 const struct btf_type *conv_struct;
5700 const struct btf_member *ctx_type;
5701
5702 conv_struct = bpf_ctx_convert.t;
5703 if (!conv_struct)
5704 return NULL;
5705 /* prog_type is valid bpf program type. No need for bounds check. */
5706 ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
5707 /* ctx_type is a pointer to prog_ctx_type in vmlinux.
5708 * Like 'struct __sk_buff'
5709 */
5710 return btf_type_by_id(btf_vmlinux, ctx_type->type);
5711 }
5712
find_kern_ctx_type_id(enum bpf_prog_type prog_type)5713 static int find_kern_ctx_type_id(enum bpf_prog_type prog_type)
5714 {
5715 const struct btf_type *conv_struct;
5716 const struct btf_member *ctx_type;
5717
5718 conv_struct = bpf_ctx_convert.t;
5719 if (!conv_struct)
5720 return -EFAULT;
5721 /* prog_type is valid bpf program type. No need for bounds check. */
5722 ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1;
5723 /* ctx_type is a pointer to prog_ctx_type in vmlinux.
5724 * Like 'struct sk_buff'
5725 */
5726 return ctx_type->type;
5727 }
5728
btf_is_prog_ctx_type(struct bpf_verifier_log * log,const struct btf * btf,const struct btf_type * t,enum bpf_prog_type prog_type,int arg)5729 bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
5730 const struct btf_type *t, enum bpf_prog_type prog_type,
5731 int arg)
5732 {
5733 const struct btf_type *ctx_type;
5734 const char *tname, *ctx_tname;
5735
5736 t = btf_type_by_id(btf, t->type);
5737
5738 /* KPROBE programs allow bpf_user_pt_regs_t typedef, which we need to
5739 * check before we skip all the typedef below.
5740 */
5741 if (prog_type == BPF_PROG_TYPE_KPROBE) {
5742 while (btf_type_is_modifier(t) && !btf_type_is_typedef(t))
5743 t = btf_type_by_id(btf, t->type);
5744
5745 if (btf_type_is_typedef(t)) {
5746 tname = btf_name_by_offset(btf, t->name_off);
5747 if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0)
5748 return true;
5749 }
5750 }
5751
5752 while (btf_type_is_modifier(t))
5753 t = btf_type_by_id(btf, t->type);
5754 if (!btf_type_is_struct(t)) {
5755 /* Only pointer to struct is supported for now.
5756 * That means that BPF_PROG_TYPE_TRACEPOINT with BTF
5757 * is not supported yet.
5758 * BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
5759 */
5760 return false;
5761 }
5762 tname = btf_name_by_offset(btf, t->name_off);
5763 if (!tname) {
5764 bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
5765 return false;
5766 }
5767
5768 ctx_type = find_canonical_prog_ctx_type(prog_type);
5769 if (!ctx_type) {
5770 bpf_log(log, "btf_vmlinux is malformed\n");
5771 /* should not happen */
5772 return false;
5773 }
5774 again:
5775 ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off);
5776 if (!ctx_tname) {
5777 /* should not happen */
5778 bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
5779 return false;
5780 }
5781 /* program types without named context types work only with arg:ctx tag */
5782 if (ctx_tname[0] == '\0')
5783 return false;
5784 /* only compare that prog's ctx type name is the same as
5785 * kernel expects. No need to compare field by field.
5786 * It's ok for bpf prog to do:
5787 * struct __sk_buff {};
5788 * int socket_filter_bpf_prog(struct __sk_buff *skb)
5789 * { // no fields of skb are ever used }
5790 */
5791 if (strcmp(ctx_tname, "__sk_buff") == 0 && strcmp(tname, "sk_buff") == 0)
5792 return true;
5793 if (strcmp(ctx_tname, "xdp_md") == 0 && strcmp(tname, "xdp_buff") == 0)
5794 return true;
5795 if (strcmp(ctx_tname, tname)) {
5796 /* bpf_user_pt_regs_t is a typedef, so resolve it to
5797 * underlying struct and check name again
5798 */
5799 if (!btf_type_is_modifier(ctx_type))
5800 return false;
5801 while (btf_type_is_modifier(ctx_type))
5802 ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type);
5803 goto again;
5804 }
5805 return true;
5806 }
5807
5808 /* forward declarations for arch-specific underlying types of
5809 * bpf_user_pt_regs_t; this avoids the need for arch-specific #ifdef
5810 * compilation guards below for BPF_PROG_TYPE_PERF_EVENT checks, but still
5811 * works correctly with __builtin_types_compatible_p() on respective
5812 * architectures
5813 */
5814 struct user_regs_struct;
5815 struct user_pt_regs;
5816
btf_validate_prog_ctx_type(struct bpf_verifier_log * log,const struct btf * btf,const struct btf_type * t,int arg,enum bpf_prog_type prog_type,enum bpf_attach_type attach_type)5817 static int btf_validate_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
5818 const struct btf_type *t, int arg,
5819 enum bpf_prog_type prog_type,
5820 enum bpf_attach_type attach_type)
5821 {
5822 const struct btf_type *ctx_type;
5823 const char *tname, *ctx_tname;
5824
5825 if (!btf_is_ptr(t)) {
5826 bpf_log(log, "arg#%d type isn't a pointer\n", arg);
5827 return -EINVAL;
5828 }
5829 t = btf_type_by_id(btf, t->type);
5830
5831 /* KPROBE and PERF_EVENT programs allow bpf_user_pt_regs_t typedef */
5832 if (prog_type == BPF_PROG_TYPE_KPROBE || prog_type == BPF_PROG_TYPE_PERF_EVENT) {
5833 while (btf_type_is_modifier(t) && !btf_type_is_typedef(t))
5834 t = btf_type_by_id(btf, t->type);
5835
5836 if (btf_type_is_typedef(t)) {
5837 tname = btf_name_by_offset(btf, t->name_off);
5838 if (tname && strcmp(tname, "bpf_user_pt_regs_t") == 0)
5839 return 0;
5840 }
5841 }
5842
5843 /* all other program types don't use typedefs for context type */
5844 while (btf_type_is_modifier(t))
5845 t = btf_type_by_id(btf, t->type);
5846
5847 /* `void *ctx __arg_ctx` is always valid */
5848 if (btf_type_is_void(t))
5849 return 0;
5850
5851 tname = btf_name_by_offset(btf, t->name_off);
5852 if (str_is_empty(tname)) {
5853 bpf_log(log, "arg#%d type doesn't have a name\n", arg);
5854 return -EINVAL;
5855 }
5856
5857 /* special cases */
5858 switch (prog_type) {
5859 case BPF_PROG_TYPE_KPROBE:
5860 if (__btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0)
5861 return 0;
5862 break;
5863 case BPF_PROG_TYPE_PERF_EVENT:
5864 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct pt_regs) &&
5865 __btf_type_is_struct(t) && strcmp(tname, "pt_regs") == 0)
5866 return 0;
5867 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_pt_regs) &&
5868 __btf_type_is_struct(t) && strcmp(tname, "user_pt_regs") == 0)
5869 return 0;
5870 if (__builtin_types_compatible_p(bpf_user_pt_regs_t, struct user_regs_struct) &&
5871 __btf_type_is_struct(t) && strcmp(tname, "user_regs_struct") == 0)
5872 return 0;
5873 break;
5874 case BPF_PROG_TYPE_RAW_TRACEPOINT:
5875 case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
5876 /* allow u64* as ctx */
5877 if (btf_is_int(t) && t->size == 8)
5878 return 0;
5879 break;
5880 case BPF_PROG_TYPE_TRACING:
5881 switch (attach_type) {
5882 case BPF_TRACE_RAW_TP:
5883 /* tp_btf program is TRACING, so need special case here */
5884 if (__btf_type_is_struct(t) &&
5885 strcmp(tname, "bpf_raw_tracepoint_args") == 0)
5886 return 0;
5887 /* allow u64* as ctx */
5888 if (btf_is_int(t) && t->size == 8)
5889 return 0;
5890 break;
5891 case BPF_TRACE_ITER:
5892 /* allow struct bpf_iter__xxx types only */
5893 if (__btf_type_is_struct(t) &&
5894 strncmp(tname, "bpf_iter__", sizeof("bpf_iter__") - 1) == 0)
5895 return 0;
5896 break;
5897 case BPF_TRACE_FENTRY:
5898 case BPF_TRACE_FEXIT:
5899 case BPF_MODIFY_RETURN:
5900 /* allow u64* as ctx */
5901 if (btf_is_int(t) && t->size == 8)
5902 return 0;
5903 break;
5904 default:
5905 break;
5906 }
5907 break;
5908 case BPF_PROG_TYPE_LSM:
5909 case BPF_PROG_TYPE_STRUCT_OPS:
5910 /* allow u64* as ctx */
5911 if (btf_is_int(t) && t->size == 8)
5912 return 0;
5913 break;
5914 case BPF_PROG_TYPE_TRACEPOINT:
5915 case BPF_PROG_TYPE_SYSCALL:
5916 case BPF_PROG_TYPE_EXT:
5917 return 0; /* anything goes */
5918 default:
5919 break;
5920 }
5921
5922 ctx_type = find_canonical_prog_ctx_type(prog_type);
5923 if (!ctx_type) {
5924 /* should not happen */
5925 bpf_log(log, "btf_vmlinux is malformed\n");
5926 return -EINVAL;
5927 }
5928
5929 /* resolve typedefs and check that underlying structs are matching as well */
5930 while (btf_type_is_modifier(ctx_type))
5931 ctx_type = btf_type_by_id(btf_vmlinux, ctx_type->type);
5932
5933 /* if program type doesn't have distinctly named struct type for
5934 * context, then __arg_ctx argument can only be `void *`, which we
5935 * already checked above
5936 */
5937 if (!__btf_type_is_struct(ctx_type)) {
5938 bpf_log(log, "arg#%d should be void pointer\n", arg);
5939 return -EINVAL;
5940 }
5941
5942 ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_type->name_off);
5943 if (!__btf_type_is_struct(t) || strcmp(ctx_tname, tname) != 0) {
5944 bpf_log(log, "arg#%d should be `struct %s *`\n", arg, ctx_tname);
5945 return -EINVAL;
5946 }
5947
5948 return 0;
5949 }
5950
btf_translate_to_vmlinux(struct bpf_verifier_log * log,struct btf * btf,const struct btf_type * t,enum bpf_prog_type prog_type,int arg)5951 static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
5952 struct btf *btf,
5953 const struct btf_type *t,
5954 enum bpf_prog_type prog_type,
5955 int arg)
5956 {
5957 if (!btf_is_prog_ctx_type(log, btf, t, prog_type, arg))
5958 return -ENOENT;
5959 return find_kern_ctx_type_id(prog_type);
5960 }
5961
get_kern_ctx_btf_id(struct bpf_verifier_log * log,enum bpf_prog_type prog_type)5962 int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type)
5963 {
5964 const struct btf_member *kctx_member;
5965 const struct btf_type *conv_struct;
5966 const struct btf_type *kctx_type;
5967 u32 kctx_type_id;
5968
5969 conv_struct = bpf_ctx_convert.t;
5970 /* get member for kernel ctx type */
5971 kctx_member = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2 + 1;
5972 kctx_type_id = kctx_member->type;
5973 kctx_type = btf_type_by_id(btf_vmlinux, kctx_type_id);
5974 if (!btf_type_is_struct(kctx_type)) {
5975 bpf_log(log, "kern ctx type id %u is not a struct\n", kctx_type_id);
5976 return -EINVAL;
5977 }
5978
5979 return kctx_type_id;
5980 }
5981
5982 BTF_ID_LIST(bpf_ctx_convert_btf_id)
BTF_ID(struct,bpf_ctx_convert)5983 BTF_ID(struct, bpf_ctx_convert)
5984
5985 struct btf *btf_parse_vmlinux(void)
5986 {
5987 struct btf_verifier_env *env = NULL;
5988 struct bpf_verifier_log *log;
5989 struct btf *btf = NULL;
5990 int err;
5991
5992 if (!IS_ENABLED(CONFIG_DEBUG_INFO_BTF))
5993 return ERR_PTR(-ENOENT);
5994
5995 env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
5996 if (!env)
5997 return ERR_PTR(-ENOMEM);
5998
5999 log = &env->log;
6000 log->level = BPF_LOG_KERNEL;
6001
6002 btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
6003 if (!btf) {
6004 err = -ENOMEM;
6005 goto errout;
6006 }
6007 env->btf = btf;
6008
6009 btf->data = __start_BTF;
6010 btf->data_size = __stop_BTF - __start_BTF;
6011 btf->kernel_btf = true;
6012 snprintf(btf->name, sizeof(btf->name), "vmlinux");
6013
6014 err = btf_parse_hdr(env);
6015 if (err)
6016 goto errout;
6017
6018 btf->nohdr_data = btf->data + btf->hdr.hdr_len;
6019
6020 err = btf_parse_str_sec(env);
6021 if (err)
6022 goto errout;
6023
6024 err = btf_check_all_metas(env);
6025 if (err)
6026 goto errout;
6027
6028 err = btf_check_type_tags(env, btf, 1);
6029 if (err)
6030 goto errout;
6031
6032 /* btf_parse_vmlinux() runs under bpf_verifier_lock */
6033 bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
6034
6035 refcount_set(&btf->refcnt, 1);
6036
6037 err = btf_alloc_id(btf);
6038 if (err)
6039 goto errout;
6040
6041 btf_verifier_env_free(env);
6042 return btf;
6043
6044 errout:
6045 btf_verifier_env_free(env);
6046 if (btf) {
6047 kvfree(btf->types);
6048 kfree(btf);
6049 }
6050 return ERR_PTR(err);
6051 }
6052
6053 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
6054
btf_parse_module(const char * module_name,const void * data,unsigned int data_size)6055 static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size)
6056 {
6057 struct btf_verifier_env *env = NULL;
6058 struct bpf_verifier_log *log;
6059 struct btf *btf = NULL, *base_btf;
6060 int err;
6061
6062 base_btf = bpf_get_btf_vmlinux();
6063 if (IS_ERR(base_btf))
6064 return base_btf;
6065 if (!base_btf)
6066 return ERR_PTR(-EINVAL);
6067
6068 env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
6069 if (!env)
6070 return ERR_PTR(-ENOMEM);
6071
6072 log = &env->log;
6073 log->level = BPF_LOG_KERNEL;
6074
6075 btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
6076 if (!btf) {
6077 err = -ENOMEM;
6078 goto errout;
6079 }
6080 env->btf = btf;
6081
6082 btf->base_btf = base_btf;
6083 btf->start_id = base_btf->nr_types;
6084 btf->start_str_off = base_btf->hdr.str_len;
6085 btf->kernel_btf = true;
6086 snprintf(btf->name, sizeof(btf->name), "%s", module_name);
6087
6088 btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN);
6089 if (!btf->data) {
6090 err = -ENOMEM;
6091 goto errout;
6092 }
6093 memcpy(btf->data, data, data_size);
6094 btf->data_size = data_size;
6095
6096 err = btf_parse_hdr(env);
6097 if (err)
6098 goto errout;
6099
6100 btf->nohdr_data = btf->data + btf->hdr.hdr_len;
6101
6102 err = btf_parse_str_sec(env);
6103 if (err)
6104 goto errout;
6105
6106 err = btf_check_all_metas(env);
6107 if (err)
6108 goto errout;
6109
6110 err = btf_check_type_tags(env, btf, btf_nr_types(base_btf));
6111 if (err)
6112 goto errout;
6113
6114 btf_verifier_env_free(env);
6115 refcount_set(&btf->refcnt, 1);
6116 return btf;
6117
6118 errout:
6119 btf_verifier_env_free(env);
6120 if (btf) {
6121 kvfree(btf->data);
6122 kvfree(btf->types);
6123 kfree(btf);
6124 }
6125 return ERR_PTR(err);
6126 }
6127
6128 #endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
6129
bpf_prog_get_target_btf(const struct bpf_prog * prog)6130 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
6131 {
6132 struct bpf_prog *tgt_prog = prog->aux->dst_prog;
6133
6134 if (tgt_prog)
6135 return tgt_prog->aux->btf;
6136 else
6137 return prog->aux->attach_btf;
6138 }
6139
is_int_ptr(struct btf * btf,const struct btf_type * t)6140 static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
6141 {
6142 /* skip modifiers */
6143 t = btf_type_skip_modifiers(btf, t->type, NULL);
6144
6145 return btf_type_is_int(t);
6146 }
6147
get_ctx_arg_idx(struct btf * btf,const struct btf_type * func_proto,int off)6148 static u32 get_ctx_arg_idx(struct btf *btf, const struct btf_type *func_proto,
6149 int off)
6150 {
6151 const struct btf_param *args;
6152 const struct btf_type *t;
6153 u32 offset = 0, nr_args;
6154 int i;
6155
6156 if (!func_proto)
6157 return off / 8;
6158
6159 nr_args = btf_type_vlen(func_proto);
6160 args = (const struct btf_param *)(func_proto + 1);
6161 for (i = 0; i < nr_args; i++) {
6162 t = btf_type_skip_modifiers(btf, args[i].type, NULL);
6163 offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
6164 if (off < offset)
6165 return i;
6166 }
6167
6168 t = btf_type_skip_modifiers(btf, func_proto->type, NULL);
6169 offset += btf_type_is_ptr(t) ? 8 : roundup(t->size, 8);
6170 if (off < offset)
6171 return nr_args;
6172
6173 return nr_args + 1;
6174 }
6175
prog_args_trusted(const struct bpf_prog * prog)6176 static bool prog_args_trusted(const struct bpf_prog *prog)
6177 {
6178 enum bpf_attach_type atype = prog->expected_attach_type;
6179
6180 switch (prog->type) {
6181 case BPF_PROG_TYPE_TRACING:
6182 return atype == BPF_TRACE_RAW_TP || atype == BPF_TRACE_ITER;
6183 case BPF_PROG_TYPE_LSM:
6184 return bpf_lsm_is_trusted(prog);
6185 case BPF_PROG_TYPE_STRUCT_OPS:
6186 return true;
6187 default:
6188 return false;
6189 }
6190 }
6191
btf_ctx_arg_offset(const struct btf * btf,const struct btf_type * func_proto,u32 arg_no)6192 int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto,
6193 u32 arg_no)
6194 {
6195 const struct btf_param *args;
6196 const struct btf_type *t;
6197 int off = 0, i;
6198 u32 sz;
6199
6200 args = btf_params(func_proto);
6201 for (i = 0; i < arg_no; i++) {
6202 t = btf_type_by_id(btf, args[i].type);
6203 t = btf_resolve_size(btf, t, &sz);
6204 if (IS_ERR(t))
6205 return PTR_ERR(t);
6206 off += roundup(sz, 8);
6207 }
6208
6209 return off;
6210 }
6211
btf_ctx_access(int off,int size,enum bpf_access_type type,const struct bpf_prog * prog,struct bpf_insn_access_aux * info)6212 bool btf_ctx_access(int off, int size, enum bpf_access_type type,
6213 const struct bpf_prog *prog,
6214 struct bpf_insn_access_aux *info)
6215 {
6216 const struct btf_type *t = prog->aux->attach_func_proto;
6217 struct bpf_prog *tgt_prog = prog->aux->dst_prog;
6218 struct btf *btf = bpf_prog_get_target_btf(prog);
6219 const char *tname = prog->aux->attach_func_name;
6220 struct bpf_verifier_log *log = info->log;
6221 const struct btf_param *args;
6222 const char *tag_value;
6223 u32 nr_args, arg;
6224 int i, ret;
6225
6226 if (off % 8) {
6227 bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
6228 tname, off);
6229 return false;
6230 }
6231 arg = get_ctx_arg_idx(btf, t, off);
6232 args = (const struct btf_param *)(t + 1);
6233 /* if (t == NULL) Fall back to default BPF prog with
6234 * MAX_BPF_FUNC_REG_ARGS u64 arguments.
6235 */
6236 nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
6237 if (prog->aux->attach_btf_trace) {
6238 /* skip first 'void *__data' argument in btf_trace_##name typedef */
6239 args++;
6240 nr_args--;
6241 }
6242
6243 if (arg > nr_args) {
6244 bpf_log(log, "func '%s' doesn't have %d-th argument\n",
6245 tname, arg + 1);
6246 return false;
6247 }
6248
6249 if (arg == nr_args) {
6250 switch (prog->expected_attach_type) {
6251 case BPF_LSM_CGROUP:
6252 case BPF_LSM_MAC:
6253 case BPF_TRACE_FEXIT:
6254 /* When LSM programs are attached to void LSM hooks
6255 * they use FEXIT trampolines and when attached to
6256 * int LSM hooks, they use MODIFY_RETURN trampolines.
6257 *
6258 * While the LSM programs are BPF_MODIFY_RETURN-like
6259 * the check:
6260 *
6261 * if (ret_type != 'int')
6262 * return -EINVAL;
6263 *
6264 * is _not_ done here. This is still safe as LSM hooks
6265 * have only void and int return types.
6266 */
6267 if (!t)
6268 return true;
6269 t = btf_type_by_id(btf, t->type);
6270 break;
6271 case BPF_MODIFY_RETURN:
6272 /* For now the BPF_MODIFY_RETURN can only be attached to
6273 * functions that return an int.
6274 */
6275 if (!t)
6276 return false;
6277
6278 t = btf_type_skip_modifiers(btf, t->type, NULL);
6279 if (!btf_type_is_small_int(t)) {
6280 bpf_log(log,
6281 "ret type %s not allowed for fmod_ret\n",
6282 btf_type_str(t));
6283 return false;
6284 }
6285 break;
6286 default:
6287 bpf_log(log, "func '%s' doesn't have %d-th argument\n",
6288 tname, arg + 1);
6289 return false;
6290 }
6291 } else {
6292 if (!t)
6293 /* Default prog with MAX_BPF_FUNC_REG_ARGS args */
6294 return true;
6295 t = btf_type_by_id(btf, args[arg].type);
6296 }
6297
6298 /* skip modifiers */
6299 while (btf_type_is_modifier(t))
6300 t = btf_type_by_id(btf, t->type);
6301 if (btf_type_is_small_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
6302 /* accessing a scalar */
6303 return true;
6304 if (!btf_type_is_ptr(t)) {
6305 bpf_log(log,
6306 "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
6307 tname, arg,
6308 __btf_name_by_offset(btf, t->name_off),
6309 btf_type_str(t));
6310 return false;
6311 }
6312
6313 /* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
6314 for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
6315 const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
6316 u32 type, flag;
6317
6318 type = base_type(ctx_arg_info->reg_type);
6319 flag = type_flag(ctx_arg_info->reg_type);
6320 if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
6321 (flag & PTR_MAYBE_NULL)) {
6322 info->reg_type = ctx_arg_info->reg_type;
6323 return true;
6324 }
6325 }
6326
6327 if (t->type == 0)
6328 /* This is a pointer to void.
6329 * It is the same as scalar from the verifier safety pov.
6330 * No further pointer walking is allowed.
6331 */
6332 return true;
6333
6334 if (is_int_ptr(btf, t))
6335 return true;
6336
6337 /* this is a pointer to another type */
6338 for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
6339 const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
6340
6341 if (ctx_arg_info->offset == off) {
6342 if (!ctx_arg_info->btf_id) {
6343 bpf_log(log,"invalid btf_id for context argument offset %u\n", off);
6344 return false;
6345 }
6346
6347 info->reg_type = ctx_arg_info->reg_type;
6348 info->btf = ctx_arg_info->btf ? : btf_vmlinux;
6349 info->btf_id = ctx_arg_info->btf_id;
6350 return true;
6351 }
6352 }
6353
6354 info->reg_type = PTR_TO_BTF_ID;
6355 if (prog_args_trusted(prog))
6356 info->reg_type |= PTR_TRUSTED;
6357
6358 if (tgt_prog) {
6359 enum bpf_prog_type tgt_type;
6360
6361 if (tgt_prog->type == BPF_PROG_TYPE_EXT)
6362 tgt_type = tgt_prog->aux->saved_dst_prog_type;
6363 else
6364 tgt_type = tgt_prog->type;
6365
6366 ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg);
6367 if (ret > 0) {
6368 info->btf = btf_vmlinux;
6369 info->btf_id = ret;
6370 return true;
6371 } else {
6372 return false;
6373 }
6374 }
6375
6376 info->btf = btf;
6377 info->btf_id = t->type;
6378 t = btf_type_by_id(btf, t->type);
6379
6380 if (btf_type_is_type_tag(t)) {
6381 tag_value = __btf_name_by_offset(btf, t->name_off);
6382 if (strcmp(tag_value, "user") == 0)
6383 info->reg_type |= MEM_USER;
6384 if (strcmp(tag_value, "percpu") == 0)
6385 info->reg_type |= MEM_PERCPU;
6386 }
6387
6388 /* skip modifiers */
6389 while (btf_type_is_modifier(t)) {
6390 info->btf_id = t->type;
6391 t = btf_type_by_id(btf, t->type);
6392 }
6393 if (!btf_type_is_struct(t)) {
6394 bpf_log(log,
6395 "func '%s' arg%d type %s is not a struct\n",
6396 tname, arg, btf_type_str(t));
6397 return false;
6398 }
6399 bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
6400 tname, arg, info->btf_id, btf_type_str(t),
6401 __btf_name_by_offset(btf, t->name_off));
6402 return true;
6403 }
6404 EXPORT_SYMBOL_GPL(btf_ctx_access);
6405
6406 enum bpf_struct_walk_result {
6407 /* < 0 error */
6408 WALK_SCALAR = 0,
6409 WALK_PTR,
6410 WALK_STRUCT,
6411 };
6412
btf_struct_walk(struct bpf_verifier_log * log,const struct btf * btf,const struct btf_type * t,int off,int size,u32 * next_btf_id,enum bpf_type_flag * flag,const char ** field_name)6413 static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
6414 const struct btf_type *t, int off, int size,
6415 u32 *next_btf_id, enum bpf_type_flag *flag,
6416 const char **field_name)
6417 {
6418 u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
6419 const struct btf_type *mtype, *elem_type = NULL;
6420 const struct btf_member *member;
6421 const char *tname, *mname, *tag_value;
6422 u32 vlen, elem_id, mid;
6423
6424 again:
6425 if (btf_type_is_modifier(t))
6426 t = btf_type_skip_modifiers(btf, t->type, NULL);
6427 tname = __btf_name_by_offset(btf, t->name_off);
6428 if (!btf_type_is_struct(t)) {
6429 bpf_log(log, "Type '%s' is not a struct\n", tname);
6430 return -EINVAL;
6431 }
6432
6433 vlen = btf_type_vlen(t);
6434 if (BTF_INFO_KIND(t->info) == BTF_KIND_UNION && vlen != 1 && !(*flag & PTR_UNTRUSTED))
6435 /*
6436 * walking unions yields untrusted pointers
6437 * with exception of __bpf_md_ptr and other
6438 * unions with a single member
6439 */
6440 *flag |= PTR_UNTRUSTED;
6441
6442 if (off + size > t->size) {
6443 /* If the last element is a variable size array, we may
6444 * need to relax the rule.
6445 */
6446 struct btf_array *array_elem;
6447
6448 if (vlen == 0)
6449 goto error;
6450
6451 member = btf_type_member(t) + vlen - 1;
6452 mtype = btf_type_skip_modifiers(btf, member->type,
6453 NULL);
6454 if (!btf_type_is_array(mtype))
6455 goto error;
6456
6457 array_elem = (struct btf_array *)(mtype + 1);
6458 if (array_elem->nelems != 0)
6459 goto error;
6460
6461 moff = __btf_member_bit_offset(t, member) / 8;
6462 if (off < moff)
6463 goto error;
6464
6465 /* allow structure and integer */
6466 t = btf_type_skip_modifiers(btf, array_elem->type,
6467 NULL);
6468
6469 if (btf_type_is_int(t))
6470 return WALK_SCALAR;
6471
6472 if (!btf_type_is_struct(t))
6473 goto error;
6474
6475 off = (off - moff) % t->size;
6476 goto again;
6477
6478 error:
6479 bpf_log(log, "access beyond struct %s at off %u size %u\n",
6480 tname, off, size);
6481 return -EACCES;
6482 }
6483
6484 for_each_member(i, t, member) {
6485 /* offset of the field in bytes */
6486 moff = __btf_member_bit_offset(t, member) / 8;
6487 if (off + size <= moff)
6488 /* won't find anything, field is already too far */
6489 break;
6490
6491 if (__btf_member_bitfield_size(t, member)) {
6492 u32 end_bit = __btf_member_bit_offset(t, member) +
6493 __btf_member_bitfield_size(t, member);
6494
6495 /* off <= moff instead of off == moff because clang
6496 * does not generate a BTF member for anonymous
6497 * bitfield like the ":16" here:
6498 * struct {
6499 * int :16;
6500 * int x:8;
6501 * };
6502 */
6503 if (off <= moff &&
6504 BITS_ROUNDUP_BYTES(end_bit) <= off + size)
6505 return WALK_SCALAR;
6506
6507 /* off may be accessing a following member
6508 *
6509 * or
6510 *
6511 * Doing partial access at either end of this
6512 * bitfield. Continue on this case also to
6513 * treat it as not accessing this bitfield
6514 * and eventually error out as field not
6515 * found to keep it simple.
6516 * It could be relaxed if there was a legit
6517 * partial access case later.
6518 */
6519 continue;
6520 }
6521
6522 /* In case of "off" is pointing to holes of a struct */
6523 if (off < moff)
6524 break;
6525
6526 /* type of the field */
6527 mid = member->type;
6528 mtype = btf_type_by_id(btf, member->type);
6529 mname = __btf_name_by_offset(btf, member->name_off);
6530
6531 mtype = __btf_resolve_size(btf, mtype, &msize,
6532 &elem_type, &elem_id, &total_nelems,
6533 &mid);
6534 if (IS_ERR(mtype)) {
6535 bpf_log(log, "field %s doesn't have size\n", mname);
6536 return -EFAULT;
6537 }
6538
6539 mtrue_end = moff + msize;
6540 if (off >= mtrue_end)
6541 /* no overlap with member, keep iterating */
6542 continue;
6543
6544 if (btf_type_is_array(mtype)) {
6545 u32 elem_idx;
6546
6547 /* __btf_resolve_size() above helps to
6548 * linearize a multi-dimensional array.
6549 *
6550 * The logic here is treating an array
6551 * in a struct as the following way:
6552 *
6553 * struct outer {
6554 * struct inner array[2][2];
6555 * };
6556 *
6557 * looks like:
6558 *
6559 * struct outer {
6560 * struct inner array_elem0;
6561 * struct inner array_elem1;
6562 * struct inner array_elem2;
6563 * struct inner array_elem3;
6564 * };
6565 *
6566 * When accessing outer->array[1][0], it moves
6567 * moff to "array_elem2", set mtype to
6568 * "struct inner", and msize also becomes
6569 * sizeof(struct inner). Then most of the
6570 * remaining logic will fall through without
6571 * caring the current member is an array or
6572 * not.
6573 *
6574 * Unlike mtype/msize/moff, mtrue_end does not
6575 * change. The naming difference ("_true") tells
6576 * that it is not always corresponding to
6577 * the current mtype/msize/moff.
6578 * It is the true end of the current
6579 * member (i.e. array in this case). That
6580 * will allow an int array to be accessed like
6581 * a scratch space,
6582 * i.e. allow access beyond the size of
6583 * the array's element as long as it is
6584 * within the mtrue_end boundary.
6585 */
6586
6587 /* skip empty array */
6588 if (moff == mtrue_end)
6589 continue;
6590
6591 msize /= total_nelems;
6592 elem_idx = (off - moff) / msize;
6593 moff += elem_idx * msize;
6594 mtype = elem_type;
6595 mid = elem_id;
6596 }
6597
6598 /* the 'off' we're looking for is either equal to start
6599 * of this field or inside of this struct
6600 */
6601 if (btf_type_is_struct(mtype)) {
6602 /* our field must be inside that union or struct */
6603 t = mtype;
6604
6605 /* return if the offset matches the member offset */
6606 if (off == moff) {
6607 *next_btf_id = mid;
6608 return WALK_STRUCT;
6609 }
6610
6611 /* adjust offset we're looking for */
6612 off -= moff;
6613 goto again;
6614 }
6615
6616 if (btf_type_is_ptr(mtype)) {
6617 const struct btf_type *stype, *t;
6618 enum bpf_type_flag tmp_flag = 0;
6619 u32 id;
6620
6621 if (msize != size || off != moff) {
6622 bpf_log(log,
6623 "cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
6624 mname, moff, tname, off, size);
6625 return -EACCES;
6626 }
6627
6628 /* check type tag */
6629 t = btf_type_by_id(btf, mtype->type);
6630 if (btf_type_is_type_tag(t)) {
6631 tag_value = __btf_name_by_offset(btf, t->name_off);
6632 /* check __user tag */
6633 if (strcmp(tag_value, "user") == 0)
6634 tmp_flag = MEM_USER;
6635 /* check __percpu tag */
6636 if (strcmp(tag_value, "percpu") == 0)
6637 tmp_flag = MEM_PERCPU;
6638 /* check __rcu tag */
6639 if (strcmp(tag_value, "rcu") == 0)
6640 tmp_flag = MEM_RCU;
6641 }
6642
6643 stype = btf_type_skip_modifiers(btf, mtype->type, &id);
6644 if (btf_type_is_struct(stype)) {
6645 *next_btf_id = id;
6646 *flag |= tmp_flag;
6647 if (field_name)
6648 *field_name = mname;
6649 return WALK_PTR;
6650 }
6651 }
6652
6653 /* Allow more flexible access within an int as long as
6654 * it is within mtrue_end.
6655 * Since mtrue_end could be the end of an array,
6656 * that also allows using an array of int as a scratch
6657 * space. e.g. skb->cb[].
6658 */
6659 if (off + size > mtrue_end && !(*flag & PTR_UNTRUSTED)) {
6660 bpf_log(log,
6661 "access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
6662 mname, mtrue_end, tname, off, size);
6663 return -EACCES;
6664 }
6665
6666 return WALK_SCALAR;
6667 }
6668 bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
6669 return -EINVAL;
6670 }
6671
btf_struct_access(struct bpf_verifier_log * log,const struct bpf_reg_state * reg,int off,int size,enum bpf_access_type atype __maybe_unused,u32 * next_btf_id,enum bpf_type_flag * flag,const char ** field_name)6672 int btf_struct_access(struct bpf_verifier_log *log,
6673 const struct bpf_reg_state *reg,
6674 int off, int size, enum bpf_access_type atype __maybe_unused,
6675 u32 *next_btf_id, enum bpf_type_flag *flag,
6676 const char **field_name)
6677 {
6678 const struct btf *btf = reg->btf;
6679 enum bpf_type_flag tmp_flag = 0;
6680 const struct btf_type *t;
6681 u32 id = reg->btf_id;
6682 int err;
6683
6684 while (type_is_alloc(reg->type)) {
6685 struct btf_struct_meta *meta;
6686 struct btf_record *rec;
6687 int i;
6688
6689 meta = btf_find_struct_meta(btf, id);
6690 if (!meta)
6691 break;
6692 rec = meta->record;
6693 for (i = 0; i < rec->cnt; i++) {
6694 struct btf_field *field = &rec->fields[i];
6695 u32 offset = field->offset;
6696 if (off < offset + btf_field_type_size(field->type) && offset < off + size) {
6697 bpf_log(log,
6698 "direct access to %s is disallowed\n",
6699 btf_field_type_name(field->type));
6700 return -EACCES;
6701 }
6702 }
6703 break;
6704 }
6705
6706 t = btf_type_by_id(btf, id);
6707 do {
6708 err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag, field_name);
6709
6710 switch (err) {
6711 case WALK_PTR:
6712 /* For local types, the destination register cannot
6713 * become a pointer again.
6714 */
6715 if (type_is_alloc(reg->type))
6716 return SCALAR_VALUE;
6717 /* If we found the pointer or scalar on t+off,
6718 * we're done.
6719 */
6720 *next_btf_id = id;
6721 *flag = tmp_flag;
6722 return PTR_TO_BTF_ID;
6723 case WALK_SCALAR:
6724 return SCALAR_VALUE;
6725 case WALK_STRUCT:
6726 /* We found nested struct, so continue the search
6727 * by diving in it. At this point the offset is
6728 * aligned with the new type, so set it to 0.
6729 */
6730 t = btf_type_by_id(btf, id);
6731 off = 0;
6732 break;
6733 default:
6734 /* It's either error or unknown return value..
6735 * scream and leave.
6736 */
6737 if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
6738 return -EINVAL;
6739 return err;
6740 }
6741 } while (t);
6742
6743 return -EINVAL;
6744 }
6745
6746 /* Check that two BTF types, each specified as an BTF object + id, are exactly
6747 * the same. Trivial ID check is not enough due to module BTFs, because we can
6748 * end up with two different module BTFs, but IDs point to the common type in
6749 * vmlinux BTF.
6750 */
btf_types_are_same(const struct btf * btf1,u32 id1,const struct btf * btf2,u32 id2)6751 bool btf_types_are_same(const struct btf *btf1, u32 id1,
6752 const struct btf *btf2, u32 id2)
6753 {
6754 if (id1 != id2)
6755 return false;
6756 if (btf1 == btf2)
6757 return true;
6758 return btf_type_by_id(btf1, id1) == btf_type_by_id(btf2, id2);
6759 }
6760
btf_struct_ids_match(struct bpf_verifier_log * log,const struct btf * btf,u32 id,int off,const struct btf * need_btf,u32 need_type_id,bool strict)6761 bool btf_struct_ids_match(struct bpf_verifier_log *log,
6762 const struct btf *btf, u32 id, int off,
6763 const struct btf *need_btf, u32 need_type_id,
6764 bool strict)
6765 {
6766 const struct btf_type *type;
6767 enum bpf_type_flag flag = 0;
6768 int err;
6769
6770 /* Are we already done? */
6771 if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id))
6772 return true;
6773 /* In case of strict type match, we do not walk struct, the top level
6774 * type match must succeed. When strict is true, off should have already
6775 * been 0.
6776 */
6777 if (strict)
6778 return false;
6779 again:
6780 type = btf_type_by_id(btf, id);
6781 if (!type)
6782 return false;
6783 err = btf_struct_walk(log, btf, type, off, 1, &id, &flag, NULL);
6784 if (err != WALK_STRUCT)
6785 return false;
6786
6787 /* We found nested struct object. If it matches
6788 * the requested ID, we're done. Otherwise let's
6789 * continue the search with offset 0 in the new
6790 * type.
6791 */
6792 if (!btf_types_are_same(btf, id, need_btf, need_type_id)) {
6793 off = 0;
6794 goto again;
6795 }
6796
6797 return true;
6798 }
6799
__get_type_size(struct btf * btf,u32 btf_id,const struct btf_type ** ret_type)6800 static int __get_type_size(struct btf *btf, u32 btf_id,
6801 const struct btf_type **ret_type)
6802 {
6803 const struct btf_type *t;
6804
6805 *ret_type = btf_type_by_id(btf, 0);
6806 if (!btf_id)
6807 /* void */
6808 return 0;
6809 t = btf_type_by_id(btf, btf_id);
6810 while (t && btf_type_is_modifier(t))
6811 t = btf_type_by_id(btf, t->type);
6812 if (!t)
6813 return -EINVAL;
6814 *ret_type = t;
6815 if (btf_type_is_ptr(t))
6816 /* kernel size of pointer. Not BPF's size of pointer*/
6817 return sizeof(void *);
6818 if (btf_type_is_int(t) || btf_is_any_enum(t) || __btf_type_is_struct(t))
6819 return t->size;
6820 return -EINVAL;
6821 }
6822
__get_type_fmodel_flags(const struct btf_type * t)6823 static u8 __get_type_fmodel_flags(const struct btf_type *t)
6824 {
6825 u8 flags = 0;
6826
6827 if (__btf_type_is_struct(t))
6828 flags |= BTF_FMODEL_STRUCT_ARG;
6829 if (btf_type_is_signed_int(t))
6830 flags |= BTF_FMODEL_SIGNED_ARG;
6831
6832 return flags;
6833 }
6834
btf_distill_func_proto(struct bpf_verifier_log * log,struct btf * btf,const struct btf_type * func,const char * tname,struct btf_func_model * m)6835 int btf_distill_func_proto(struct bpf_verifier_log *log,
6836 struct btf *btf,
6837 const struct btf_type *func,
6838 const char *tname,
6839 struct btf_func_model *m)
6840 {
6841 const struct btf_param *args;
6842 const struct btf_type *t;
6843 u32 i, nargs;
6844 int ret;
6845
6846 if (!func) {
6847 /* BTF function prototype doesn't match the verifier types.
6848 * Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
6849 */
6850 for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++) {
6851 m->arg_size[i] = 8;
6852 m->arg_flags[i] = 0;
6853 }
6854 m->ret_size = 8;
6855 m->ret_flags = 0;
6856 m->nr_args = MAX_BPF_FUNC_REG_ARGS;
6857 return 0;
6858 }
6859 args = (const struct btf_param *)(func + 1);
6860 nargs = btf_type_vlen(func);
6861 if (nargs > MAX_BPF_FUNC_ARGS) {
6862 bpf_log(log,
6863 "The function %s has %d arguments. Too many.\n",
6864 tname, nargs);
6865 return -EINVAL;
6866 }
6867 ret = __get_type_size(btf, func->type, &t);
6868 if (ret < 0 || __btf_type_is_struct(t)) {
6869 bpf_log(log,
6870 "The function %s return type %s is unsupported.\n",
6871 tname, btf_type_str(t));
6872 return -EINVAL;
6873 }
6874 m->ret_size = ret;
6875 m->ret_flags = __get_type_fmodel_flags(t);
6876
6877 for (i = 0; i < nargs; i++) {
6878 if (i == nargs - 1 && args[i].type == 0) {
6879 bpf_log(log,
6880 "The function %s with variable args is unsupported.\n",
6881 tname);
6882 return -EINVAL;
6883 }
6884 ret = __get_type_size(btf, args[i].type, &t);
6885
6886 /* No support of struct argument size greater than 16 bytes */
6887 if (ret < 0 || ret > 16) {
6888 bpf_log(log,
6889 "The function %s arg%d type %s is unsupported.\n",
6890 tname, i, btf_type_str(t));
6891 return -EINVAL;
6892 }
6893 if (ret == 0) {
6894 bpf_log(log,
6895 "The function %s has malformed void argument.\n",
6896 tname);
6897 return -EINVAL;
6898 }
6899 m->arg_size[i] = ret;
6900 m->arg_flags[i] = __get_type_fmodel_flags(t);
6901 }
6902 m->nr_args = nargs;
6903 return 0;
6904 }
6905
6906 /* Compare BTFs of two functions assuming only scalars and pointers to context.
6907 * t1 points to BTF_KIND_FUNC in btf1
6908 * t2 points to BTF_KIND_FUNC in btf2
6909 * Returns:
6910 * EINVAL - function prototype mismatch
6911 * EFAULT - verifier bug
6912 * 0 - 99% match. The last 1% is validated by the verifier.
6913 */
btf_check_func_type_match(struct bpf_verifier_log * log,struct btf * btf1,const struct btf_type * t1,struct btf * btf2,const struct btf_type * t2)6914 static int btf_check_func_type_match(struct bpf_verifier_log *log,
6915 struct btf *btf1, const struct btf_type *t1,
6916 struct btf *btf2, const struct btf_type *t2)
6917 {
6918 const struct btf_param *args1, *args2;
6919 const char *fn1, *fn2, *s1, *s2;
6920 u32 nargs1, nargs2, i;
6921
6922 fn1 = btf_name_by_offset(btf1, t1->name_off);
6923 fn2 = btf_name_by_offset(btf2, t2->name_off);
6924
6925 if (btf_func_linkage(t1) != BTF_FUNC_GLOBAL) {
6926 bpf_log(log, "%s() is not a global function\n", fn1);
6927 return -EINVAL;
6928 }
6929 if (btf_func_linkage(t2) != BTF_FUNC_GLOBAL) {
6930 bpf_log(log, "%s() is not a global function\n", fn2);
6931 return -EINVAL;
6932 }
6933
6934 t1 = btf_type_by_id(btf1, t1->type);
6935 if (!t1 || !btf_type_is_func_proto(t1))
6936 return -EFAULT;
6937 t2 = btf_type_by_id(btf2, t2->type);
6938 if (!t2 || !btf_type_is_func_proto(t2))
6939 return -EFAULT;
6940
6941 args1 = (const struct btf_param *)(t1 + 1);
6942 nargs1 = btf_type_vlen(t1);
6943 args2 = (const struct btf_param *)(t2 + 1);
6944 nargs2 = btf_type_vlen(t2);
6945
6946 if (nargs1 != nargs2) {
6947 bpf_log(log, "%s() has %d args while %s() has %d args\n",
6948 fn1, nargs1, fn2, nargs2);
6949 return -EINVAL;
6950 }
6951
6952 t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
6953 t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
6954 if (t1->info != t2->info) {
6955 bpf_log(log,
6956 "Return type %s of %s() doesn't match type %s of %s()\n",
6957 btf_type_str(t1), fn1,
6958 btf_type_str(t2), fn2);
6959 return -EINVAL;
6960 }
6961
6962 for (i = 0; i < nargs1; i++) {
6963 t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
6964 t2 = btf_type_skip_modifiers(btf2, args2[i].type, NULL);
6965
6966 if (t1->info != t2->info) {
6967 bpf_log(log, "arg%d in %s() is %s while %s() has %s\n",
6968 i, fn1, btf_type_str(t1),
6969 fn2, btf_type_str(t2));
6970 return -EINVAL;
6971 }
6972 if (btf_type_has_size(t1) && t1->size != t2->size) {
6973 bpf_log(log,
6974 "arg%d in %s() has size %d while %s() has %d\n",
6975 i, fn1, t1->size,
6976 fn2, t2->size);
6977 return -EINVAL;
6978 }
6979
6980 /* global functions are validated with scalars and pointers
6981 * to context only. And only global functions can be replaced.
6982 * Hence type check only those types.
6983 */
6984 if (btf_type_is_int(t1) || btf_is_any_enum(t1))
6985 continue;
6986 if (!btf_type_is_ptr(t1)) {
6987 bpf_log(log,
6988 "arg%d in %s() has unrecognized type\n",
6989 i, fn1);
6990 return -EINVAL;
6991 }
6992 t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
6993 t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
6994 if (!btf_type_is_struct(t1)) {
6995 bpf_log(log,
6996 "arg%d in %s() is not a pointer to context\n",
6997 i, fn1);
6998 return -EINVAL;
6999 }
7000 if (!btf_type_is_struct(t2)) {
7001 bpf_log(log,
7002 "arg%d in %s() is not a pointer to context\n",
7003 i, fn2);
7004 return -EINVAL;
7005 }
7006 /* This is an optional check to make program writing easier.
7007 * Compare names of structs and report an error to the user.
7008 * btf_prepare_func_args() already checked that t2 struct
7009 * is a context type. btf_prepare_func_args() will check
7010 * later that t1 struct is a context type as well.
7011 */
7012 s1 = btf_name_by_offset(btf1, t1->name_off);
7013 s2 = btf_name_by_offset(btf2, t2->name_off);
7014 if (strcmp(s1, s2)) {
7015 bpf_log(log,
7016 "arg%d %s(struct %s *) doesn't match %s(struct %s *)\n",
7017 i, fn1, s1, fn2, s2);
7018 return -EINVAL;
7019 }
7020 }
7021 return 0;
7022 }
7023
7024 /* Compare BTFs of given program with BTF of target program */
btf_check_type_match(struct bpf_verifier_log * log,const struct bpf_prog * prog,struct btf * btf2,const struct btf_type * t2)7025 int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
7026 struct btf *btf2, const struct btf_type *t2)
7027 {
7028 struct btf *btf1 = prog->aux->btf;
7029 const struct btf_type *t1;
7030 u32 btf_id = 0;
7031
7032 if (!prog->aux->func_info) {
7033 bpf_log(log, "Program extension requires BTF\n");
7034 return -EINVAL;
7035 }
7036
7037 btf_id = prog->aux->func_info[0].type_id;
7038 if (!btf_id)
7039 return -EFAULT;
7040
7041 t1 = btf_type_by_id(btf1, btf_id);
7042 if (!t1 || !btf_type_is_func(t1))
7043 return -EFAULT;
7044
7045 return btf_check_func_type_match(log, btf1, t1, btf2, t2);
7046 }
7047
btf_is_dynptr_ptr(const struct btf * btf,const struct btf_type * t)7048 static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t)
7049 {
7050 const char *name;
7051
7052 t = btf_type_by_id(btf, t->type); /* skip PTR */
7053
7054 while (btf_type_is_modifier(t))
7055 t = btf_type_by_id(btf, t->type);
7056
7057 /* allow either struct or struct forward declaration */
7058 if (btf_type_is_struct(t) ||
7059 (btf_type_is_fwd(t) && btf_type_kflag(t) == 0)) {
7060 name = btf_str_by_offset(btf, t->name_off);
7061 return name && strcmp(name, "bpf_dynptr") == 0;
7062 }
7063
7064 return false;
7065 }
7066
7067 struct bpf_cand_cache {
7068 const char *name;
7069 u32 name_len;
7070 u16 kind;
7071 u16 cnt;
7072 struct {
7073 const struct btf *btf;
7074 u32 id;
7075 } cands[];
7076 };
7077
7078 static DEFINE_MUTEX(cand_cache_mutex);
7079
7080 static struct bpf_cand_cache *
7081 bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id);
7082
btf_get_ptr_to_btf_id(struct bpf_verifier_log * log,int arg_idx,const struct btf * btf,const struct btf_type * t)7083 static int btf_get_ptr_to_btf_id(struct bpf_verifier_log *log, int arg_idx,
7084 const struct btf *btf, const struct btf_type *t)
7085 {
7086 struct bpf_cand_cache *cc;
7087 struct bpf_core_ctx ctx = {
7088 .btf = btf,
7089 .log = log,
7090 };
7091 u32 kern_type_id, type_id;
7092 int err = 0;
7093
7094 /* skip PTR and modifiers */
7095 type_id = t->type;
7096 t = btf_type_by_id(btf, t->type);
7097 while (btf_type_is_modifier(t)) {
7098 type_id = t->type;
7099 t = btf_type_by_id(btf, t->type);
7100 }
7101
7102 mutex_lock(&cand_cache_mutex);
7103 cc = bpf_core_find_cands(&ctx, type_id);
7104 if (IS_ERR(cc)) {
7105 err = PTR_ERR(cc);
7106 bpf_log(log, "arg#%d reference type('%s %s') candidate matching error: %d\n",
7107 arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off),
7108 err);
7109 goto cand_cache_unlock;
7110 }
7111 if (cc->cnt != 1) {
7112 bpf_log(log, "arg#%d reference type('%s %s') %s\n",
7113 arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off),
7114 cc->cnt == 0 ? "has no matches" : "is ambiguous");
7115 err = cc->cnt == 0 ? -ENOENT : -ESRCH;
7116 goto cand_cache_unlock;
7117 }
7118 if (btf_is_module(cc->cands[0].btf)) {
7119 bpf_log(log, "arg#%d reference type('%s %s') points to kernel module type (unsupported)\n",
7120 arg_idx, btf_type_str(t), __btf_name_by_offset(btf, t->name_off));
7121 err = -EOPNOTSUPP;
7122 goto cand_cache_unlock;
7123 }
7124 kern_type_id = cc->cands[0].id;
7125
7126 cand_cache_unlock:
7127 mutex_unlock(&cand_cache_mutex);
7128 if (err)
7129 return err;
7130
7131 return kern_type_id;
7132 }
7133
7134 enum btf_arg_tag {
7135 ARG_TAG_CTX = BIT_ULL(0),
7136 ARG_TAG_NONNULL = BIT_ULL(1),
7137 ARG_TAG_TRUSTED = BIT_ULL(2),
7138 ARG_TAG_NULLABLE = BIT_ULL(3),
7139 ARG_TAG_ARENA = BIT_ULL(4),
7140 };
7141
7142 /* Process BTF of a function to produce high-level expectation of function
7143 * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information
7144 * is cached in subprog info for reuse.
7145 * Returns:
7146 * EFAULT - there is a verifier bug. Abort verification.
7147 * EINVAL - cannot convert BTF.
7148 * 0 - Successfully processed BTF and constructed argument expectations.
7149 */
btf_prepare_func_args(struct bpf_verifier_env * env,int subprog)7150 int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
7151 {
7152 bool is_global = subprog_aux(env, subprog)->linkage == BTF_FUNC_GLOBAL;
7153 struct bpf_subprog_info *sub = subprog_info(env, subprog);
7154 struct bpf_verifier_log *log = &env->log;
7155 struct bpf_prog *prog = env->prog;
7156 enum bpf_prog_type prog_type = prog->type;
7157 struct btf *btf = prog->aux->btf;
7158 const struct btf_param *args;
7159 const struct btf_type *t, *ref_t, *fn_t;
7160 u32 i, nargs, btf_id;
7161 const char *tname;
7162
7163 if (sub->args_cached)
7164 return 0;
7165
7166 if (!prog->aux->func_info) {
7167 bpf_log(log, "Verifier bug\n");
7168 return -EFAULT;
7169 }
7170
7171 btf_id = prog->aux->func_info[subprog].type_id;
7172 if (!btf_id) {
7173 if (!is_global) /* not fatal for static funcs */
7174 return -EINVAL;
7175 bpf_log(log, "Global functions need valid BTF\n");
7176 return -EFAULT;
7177 }
7178
7179 fn_t = btf_type_by_id(btf, btf_id);
7180 if (!fn_t || !btf_type_is_func(fn_t)) {
7181 /* These checks were already done by the verifier while loading
7182 * struct bpf_func_info
7183 */
7184 bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
7185 subprog);
7186 return -EFAULT;
7187 }
7188 tname = btf_name_by_offset(btf, fn_t->name_off);
7189
7190 if (prog->aux->func_info_aux[subprog].unreliable) {
7191 bpf_log(log, "Verifier bug in function %s()\n", tname);
7192 return -EFAULT;
7193 }
7194 if (prog_type == BPF_PROG_TYPE_EXT)
7195 prog_type = prog->aux->dst_prog->type;
7196
7197 t = btf_type_by_id(btf, fn_t->type);
7198 if (!t || !btf_type_is_func_proto(t)) {
7199 bpf_log(log, "Invalid type of function %s()\n", tname);
7200 return -EFAULT;
7201 }
7202 args = (const struct btf_param *)(t + 1);
7203 nargs = btf_type_vlen(t);
7204 if (nargs > MAX_BPF_FUNC_REG_ARGS) {
7205 if (!is_global)
7206 return -EINVAL;
7207 bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
7208 tname, nargs, MAX_BPF_FUNC_REG_ARGS);
7209 return -EINVAL;
7210 }
7211 /* check that function returns int, exception cb also requires this */
7212 t = btf_type_by_id(btf, t->type);
7213 while (btf_type_is_modifier(t))
7214 t = btf_type_by_id(btf, t->type);
7215 if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
7216 if (!is_global)
7217 return -EINVAL;
7218 bpf_log(log,
7219 "Global function %s() doesn't return scalar. Only those are supported.\n",
7220 tname);
7221 return -EINVAL;
7222 }
7223 /* Convert BTF function arguments into verifier types.
7224 * Only PTR_TO_CTX and SCALAR are supported atm.
7225 */
7226 for (i = 0; i < nargs; i++) {
7227 u32 tags = 0;
7228 int id = 0;
7229
7230 /* 'arg:<tag>' decl_tag takes precedence over derivation of
7231 * register type from BTF type itself
7232 */
7233 while ((id = btf_find_next_decl_tag(btf, fn_t, i, "arg:", id)) > 0) {
7234 const struct btf_type *tag_t = btf_type_by_id(btf, id);
7235 const char *tag = __btf_name_by_offset(btf, tag_t->name_off) + 4;
7236
7237 /* disallow arg tags in static subprogs */
7238 if (!is_global) {
7239 bpf_log(log, "arg#%d type tag is not supported in static functions\n", i);
7240 return -EOPNOTSUPP;
7241 }
7242
7243 if (strcmp(tag, "ctx") == 0) {
7244 tags |= ARG_TAG_CTX;
7245 } else if (strcmp(tag, "trusted") == 0) {
7246 tags |= ARG_TAG_TRUSTED;
7247 } else if (strcmp(tag, "nonnull") == 0) {
7248 tags |= ARG_TAG_NONNULL;
7249 } else if (strcmp(tag, "nullable") == 0) {
7250 tags |= ARG_TAG_NULLABLE;
7251 } else if (strcmp(tag, "arena") == 0) {
7252 tags |= ARG_TAG_ARENA;
7253 } else {
7254 bpf_log(log, "arg#%d has unsupported set of tags\n", i);
7255 return -EOPNOTSUPP;
7256 }
7257 }
7258 if (id != -ENOENT) {
7259 bpf_log(log, "arg#%d type tag fetching failure: %d\n", i, id);
7260 return id;
7261 }
7262
7263 t = btf_type_by_id(btf, args[i].type);
7264 while (btf_type_is_modifier(t))
7265 t = btf_type_by_id(btf, t->type);
7266 if (!btf_type_is_ptr(t))
7267 goto skip_pointer;
7268
7269 if ((tags & ARG_TAG_CTX) || btf_is_prog_ctx_type(log, btf, t, prog_type, i)) {
7270 if (tags & ~ARG_TAG_CTX) {
7271 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
7272 return -EINVAL;
7273 }
7274 if ((tags & ARG_TAG_CTX) &&
7275 btf_validate_prog_ctx_type(log, btf, t, i, prog_type,
7276 prog->expected_attach_type))
7277 return -EINVAL;
7278 sub->args[i].arg_type = ARG_PTR_TO_CTX;
7279 continue;
7280 }
7281 if (btf_is_dynptr_ptr(btf, t)) {
7282 if (tags) {
7283 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
7284 return -EINVAL;
7285 }
7286 sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY;
7287 continue;
7288 }
7289 if (tags & ARG_TAG_TRUSTED) {
7290 int kern_type_id;
7291
7292 if (tags & ARG_TAG_NONNULL) {
7293 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
7294 return -EINVAL;
7295 }
7296
7297 kern_type_id = btf_get_ptr_to_btf_id(log, i, btf, t);
7298 if (kern_type_id < 0)
7299 return kern_type_id;
7300
7301 sub->args[i].arg_type = ARG_PTR_TO_BTF_ID | PTR_TRUSTED;
7302 if (tags & ARG_TAG_NULLABLE)
7303 sub->args[i].arg_type |= PTR_MAYBE_NULL;
7304 sub->args[i].btf_id = kern_type_id;
7305 continue;
7306 }
7307 if (tags & ARG_TAG_ARENA) {
7308 if (tags & ~ARG_TAG_ARENA) {
7309 bpf_log(log, "arg#%d arena cannot be combined with any other tags\n", i);
7310 return -EINVAL;
7311 }
7312 sub->args[i].arg_type = ARG_PTR_TO_ARENA;
7313 continue;
7314 }
7315 if (is_global) { /* generic user data pointer */
7316 u32 mem_size;
7317
7318 if (tags & ARG_TAG_NULLABLE) {
7319 bpf_log(log, "arg#%d has invalid combination of tags\n", i);
7320 return -EINVAL;
7321 }
7322
7323 t = btf_type_skip_modifiers(btf, t->type, NULL);
7324 ref_t = btf_resolve_size(btf, t, &mem_size);
7325 if (IS_ERR(ref_t)) {
7326 bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n",
7327 i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
7328 PTR_ERR(ref_t));
7329 return -EINVAL;
7330 }
7331
7332 sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL;
7333 if (tags & ARG_TAG_NONNULL)
7334 sub->args[i].arg_type &= ~PTR_MAYBE_NULL;
7335 sub->args[i].mem_size = mem_size;
7336 continue;
7337 }
7338
7339 skip_pointer:
7340 if (tags) {
7341 bpf_log(log, "arg#%d has pointer tag, but is not a pointer type\n", i);
7342 return -EINVAL;
7343 }
7344 if (btf_type_is_int(t) || btf_is_any_enum(t)) {
7345 sub->args[i].arg_type = ARG_ANYTHING;
7346 continue;
7347 }
7348 if (!is_global)
7349 return -EINVAL;
7350 bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
7351 i, btf_type_str(t), tname);
7352 return -EINVAL;
7353 }
7354
7355 sub->arg_cnt = nargs;
7356 sub->args_cached = true;
7357
7358 return 0;
7359 }
7360
btf_type_show(const struct btf * btf,u32 type_id,void * obj,struct btf_show * show)7361 static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
7362 struct btf_show *show)
7363 {
7364 const struct btf_type *t = btf_type_by_id(btf, type_id);
7365
7366 show->btf = btf;
7367 memset(&show->state, 0, sizeof(show->state));
7368 memset(&show->obj, 0, sizeof(show->obj));
7369
7370 btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
7371 }
7372
btf_seq_show(struct btf_show * show,const char * fmt,va_list args)7373 static void btf_seq_show(struct btf_show *show, const char *fmt,
7374 va_list args)
7375 {
7376 seq_vprintf((struct seq_file *)show->target, fmt, args);
7377 }
7378
btf_type_seq_show_flags(const struct btf * btf,u32 type_id,void * obj,struct seq_file * m,u64 flags)7379 int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
7380 void *obj, struct seq_file *m, u64 flags)
7381 {
7382 struct btf_show sseq;
7383
7384 sseq.target = m;
7385 sseq.showfn = btf_seq_show;
7386 sseq.flags = flags;
7387
7388 btf_type_show(btf, type_id, obj, &sseq);
7389
7390 return sseq.state.status;
7391 }
7392
btf_type_seq_show(const struct btf * btf,u32 type_id,void * obj,struct seq_file * m)7393 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
7394 struct seq_file *m)
7395 {
7396 (void) btf_type_seq_show_flags(btf, type_id, obj, m,
7397 BTF_SHOW_NONAME | BTF_SHOW_COMPACT |
7398 BTF_SHOW_ZERO | BTF_SHOW_UNSAFE);
7399 }
7400
7401 struct btf_show_snprintf {
7402 struct btf_show show;
7403 int len_left; /* space left in string */
7404 int len; /* length we would have written */
7405 };
7406
btf_snprintf_show(struct btf_show * show,const char * fmt,va_list args)7407 static void btf_snprintf_show(struct btf_show *show, const char *fmt,
7408 va_list args)
7409 {
7410 struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
7411 int len;
7412
7413 len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
7414
7415 if (len < 0) {
7416 ssnprintf->len_left = 0;
7417 ssnprintf->len = len;
7418 } else if (len >= ssnprintf->len_left) {
7419 /* no space, drive on to get length we would have written */
7420 ssnprintf->len_left = 0;
7421 ssnprintf->len += len;
7422 } else {
7423 ssnprintf->len_left -= len;
7424 ssnprintf->len += len;
7425 show->target += len;
7426 }
7427 }
7428
btf_type_snprintf_show(const struct btf * btf,u32 type_id,void * obj,char * buf,int len,u64 flags)7429 int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
7430 char *buf, int len, u64 flags)
7431 {
7432 struct btf_show_snprintf ssnprintf;
7433
7434 ssnprintf.show.target = buf;
7435 ssnprintf.show.flags = flags;
7436 ssnprintf.show.showfn = btf_snprintf_show;
7437 ssnprintf.len_left = len;
7438 ssnprintf.len = 0;
7439
7440 btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf);
7441
7442 /* If we encountered an error, return it. */
7443 if (ssnprintf.show.state.status)
7444 return ssnprintf.show.state.status;
7445
7446 /* Otherwise return length we would have written */
7447 return ssnprintf.len;
7448 }
7449
7450 #ifdef CONFIG_PROC_FS
bpf_btf_show_fdinfo(struct seq_file * m,struct file * filp)7451 static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
7452 {
7453 const struct btf *btf = filp->private_data;
7454
7455 seq_printf(m, "btf_id:\t%u\n", btf->id);
7456 }
7457 #endif
7458
btf_release(struct inode * inode,struct file * filp)7459 static int btf_release(struct inode *inode, struct file *filp)
7460 {
7461 btf_put(filp->private_data);
7462 return 0;
7463 }
7464
7465 const struct file_operations btf_fops = {
7466 #ifdef CONFIG_PROC_FS
7467 .show_fdinfo = bpf_btf_show_fdinfo,
7468 #endif
7469 .release = btf_release,
7470 };
7471
__btf_new_fd(struct btf * btf)7472 static int __btf_new_fd(struct btf *btf)
7473 {
7474 return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
7475 }
7476
btf_new_fd(const union bpf_attr * attr,bpfptr_t uattr,u32 uattr_size)7477 int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr, u32 uattr_size)
7478 {
7479 struct btf *btf;
7480 int ret;
7481
7482 btf = btf_parse(attr, uattr, uattr_size);
7483 if (IS_ERR(btf))
7484 return PTR_ERR(btf);
7485
7486 ret = btf_alloc_id(btf);
7487 if (ret) {
7488 btf_free(btf);
7489 return ret;
7490 }
7491
7492 /*
7493 * The BTF ID is published to the userspace.
7494 * All BTF free must go through call_rcu() from
7495 * now on (i.e. free by calling btf_put()).
7496 */
7497
7498 ret = __btf_new_fd(btf);
7499 if (ret < 0)
7500 btf_put(btf);
7501
7502 return ret;
7503 }
7504
btf_get_by_fd(int fd)7505 struct btf *btf_get_by_fd(int fd)
7506 {
7507 struct btf *btf;
7508 struct fd f;
7509
7510 f = fdget(fd);
7511
7512 if (!f.file)
7513 return ERR_PTR(-EBADF);
7514
7515 if (f.file->f_op != &btf_fops) {
7516 fdput(f);
7517 return ERR_PTR(-EINVAL);
7518 }
7519
7520 btf = f.file->private_data;
7521 refcount_inc(&btf->refcnt);
7522 fdput(f);
7523
7524 return btf;
7525 }
7526
btf_get_info_by_fd(const struct btf * btf,const union bpf_attr * attr,union bpf_attr __user * uattr)7527 int btf_get_info_by_fd(const struct btf *btf,
7528 const union bpf_attr *attr,
7529 union bpf_attr __user *uattr)
7530 {
7531 struct bpf_btf_info __user *uinfo;
7532 struct bpf_btf_info info;
7533 u32 info_copy, btf_copy;
7534 void __user *ubtf;
7535 char __user *uname;
7536 u32 uinfo_len, uname_len, name_len;
7537 int ret = 0;
7538
7539 uinfo = u64_to_user_ptr(attr->info.info);
7540 uinfo_len = attr->info.info_len;
7541
7542 info_copy = min_t(u32, uinfo_len, sizeof(info));
7543 memset(&info, 0, sizeof(info));
7544 if (copy_from_user(&info, uinfo, info_copy))
7545 return -EFAULT;
7546
7547 info.id = btf->id;
7548 ubtf = u64_to_user_ptr(info.btf);
7549 btf_copy = min_t(u32, btf->data_size, info.btf_size);
7550 if (copy_to_user(ubtf, btf->data, btf_copy))
7551 return -EFAULT;
7552 info.btf_size = btf->data_size;
7553
7554 info.kernel_btf = btf->kernel_btf;
7555
7556 uname = u64_to_user_ptr(info.name);
7557 uname_len = info.name_len;
7558 if (!uname ^ !uname_len)
7559 return -EINVAL;
7560
7561 name_len = strlen(btf->name);
7562 info.name_len = name_len;
7563
7564 if (uname) {
7565 if (uname_len >= name_len + 1) {
7566 if (copy_to_user(uname, btf->name, name_len + 1))
7567 return -EFAULT;
7568 } else {
7569 char zero = '\0';
7570
7571 if (copy_to_user(uname, btf->name, uname_len - 1))
7572 return -EFAULT;
7573 if (put_user(zero, uname + uname_len - 1))
7574 return -EFAULT;
7575 /* let user-space know about too short buffer */
7576 ret = -ENOSPC;
7577 }
7578 }
7579
7580 if (copy_to_user(uinfo, &info, info_copy) ||
7581 put_user(info_copy, &uattr->info.info_len))
7582 return -EFAULT;
7583
7584 return ret;
7585 }
7586
btf_get_fd_by_id(u32 id)7587 int btf_get_fd_by_id(u32 id)
7588 {
7589 struct btf *btf;
7590 int fd;
7591
7592 rcu_read_lock();
7593 btf = idr_find(&btf_idr, id);
7594 if (!btf || !refcount_inc_not_zero(&btf->refcnt))
7595 btf = ERR_PTR(-ENOENT);
7596 rcu_read_unlock();
7597
7598 if (IS_ERR(btf))
7599 return PTR_ERR(btf);
7600
7601 fd = __btf_new_fd(btf);
7602 if (fd < 0)
7603 btf_put(btf);
7604
7605 return fd;
7606 }
7607
btf_obj_id(const struct btf * btf)7608 u32 btf_obj_id(const struct btf *btf)
7609 {
7610 return btf->id;
7611 }
7612
btf_is_kernel(const struct btf * btf)7613 bool btf_is_kernel(const struct btf *btf)
7614 {
7615 return btf->kernel_btf;
7616 }
7617
btf_is_module(const struct btf * btf)7618 bool btf_is_module(const struct btf *btf)
7619 {
7620 return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0;
7621 }
7622
7623 enum {
7624 BTF_MODULE_F_LIVE = (1 << 0),
7625 };
7626
7627 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
7628 struct btf_module {
7629 struct list_head list;
7630 struct module *module;
7631 struct btf *btf;
7632 struct bin_attribute *sysfs_attr;
7633 int flags;
7634 };
7635
7636 static LIST_HEAD(btf_modules);
7637 static DEFINE_MUTEX(btf_module_mutex);
7638
7639 static ssize_t
btf_module_read(struct file * file,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t off,size_t len)7640 btf_module_read(struct file *file, struct kobject *kobj,
7641 struct bin_attribute *bin_attr,
7642 char *buf, loff_t off, size_t len)
7643 {
7644 const struct btf *btf = bin_attr->private;
7645
7646 memcpy(buf, btf->data + off, len);
7647 return len;
7648 }
7649
7650 static void purge_cand_cache(struct btf *btf);
7651
btf_module_notify(struct notifier_block * nb,unsigned long op,void * module)7652 static int btf_module_notify(struct notifier_block *nb, unsigned long op,
7653 void *module)
7654 {
7655 struct btf_module *btf_mod, *tmp;
7656 struct module *mod = module;
7657 struct btf *btf;
7658 int err = 0;
7659
7660 if (mod->btf_data_size == 0 ||
7661 (op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE &&
7662 op != MODULE_STATE_GOING))
7663 goto out;
7664
7665 switch (op) {
7666 case MODULE_STATE_COMING:
7667 btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL);
7668 if (!btf_mod) {
7669 err = -ENOMEM;
7670 goto out;
7671 }
7672 btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size);
7673 if (IS_ERR(btf)) {
7674 kfree(btf_mod);
7675 if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
7676 pr_warn("failed to validate module [%s] BTF: %ld\n",
7677 mod->name, PTR_ERR(btf));
7678 err = PTR_ERR(btf);
7679 } else {
7680 pr_warn_once("Kernel module BTF mismatch detected, BTF debug info may be unavailable for some modules\n");
7681 }
7682 goto out;
7683 }
7684 err = btf_alloc_id(btf);
7685 if (err) {
7686 btf_free(btf);
7687 kfree(btf_mod);
7688 goto out;
7689 }
7690
7691 purge_cand_cache(NULL);
7692 mutex_lock(&btf_module_mutex);
7693 btf_mod->module = module;
7694 btf_mod->btf = btf;
7695 list_add(&btf_mod->list, &btf_modules);
7696 mutex_unlock(&btf_module_mutex);
7697
7698 if (IS_ENABLED(CONFIG_SYSFS)) {
7699 struct bin_attribute *attr;
7700
7701 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
7702 if (!attr)
7703 goto out;
7704
7705 sysfs_bin_attr_init(attr);
7706 attr->attr.name = btf->name;
7707 attr->attr.mode = 0444;
7708 attr->size = btf->data_size;
7709 attr->private = btf;
7710 attr->read = btf_module_read;
7711
7712 err = sysfs_create_bin_file(btf_kobj, attr);
7713 if (err) {
7714 pr_warn("failed to register module [%s] BTF in sysfs: %d\n",
7715 mod->name, err);
7716 kfree(attr);
7717 err = 0;
7718 goto out;
7719 }
7720
7721 btf_mod->sysfs_attr = attr;
7722 }
7723
7724 break;
7725 case MODULE_STATE_LIVE:
7726 mutex_lock(&btf_module_mutex);
7727 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
7728 if (btf_mod->module != module)
7729 continue;
7730
7731 btf_mod->flags |= BTF_MODULE_F_LIVE;
7732 break;
7733 }
7734 mutex_unlock(&btf_module_mutex);
7735 break;
7736 case MODULE_STATE_GOING:
7737 mutex_lock(&btf_module_mutex);
7738 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
7739 if (btf_mod->module != module)
7740 continue;
7741
7742 list_del(&btf_mod->list);
7743 if (btf_mod->sysfs_attr)
7744 sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
7745 purge_cand_cache(btf_mod->btf);
7746 btf_put(btf_mod->btf);
7747 kfree(btf_mod->sysfs_attr);
7748 kfree(btf_mod);
7749 break;
7750 }
7751 mutex_unlock(&btf_module_mutex);
7752 break;
7753 }
7754 out:
7755 return notifier_from_errno(err);
7756 }
7757
7758 static struct notifier_block btf_module_nb = {
7759 .notifier_call = btf_module_notify,
7760 };
7761
btf_module_init(void)7762 static int __init btf_module_init(void)
7763 {
7764 register_module_notifier(&btf_module_nb);
7765 return 0;
7766 }
7767
7768 fs_initcall(btf_module_init);
7769 #endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
7770
btf_try_get_module(const struct btf * btf)7771 struct module *btf_try_get_module(const struct btf *btf)
7772 {
7773 struct module *res = NULL;
7774 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
7775 struct btf_module *btf_mod, *tmp;
7776
7777 mutex_lock(&btf_module_mutex);
7778 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
7779 if (btf_mod->btf != btf)
7780 continue;
7781
7782 /* We must only consider module whose __init routine has
7783 * finished, hence we must check for BTF_MODULE_F_LIVE flag,
7784 * which is set from the notifier callback for
7785 * MODULE_STATE_LIVE.
7786 */
7787 if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module))
7788 res = btf_mod->module;
7789
7790 break;
7791 }
7792 mutex_unlock(&btf_module_mutex);
7793 #endif
7794
7795 return res;
7796 }
7797
7798 /* Returns struct btf corresponding to the struct module.
7799 * This function can return NULL or ERR_PTR.
7800 */
btf_get_module_btf(const struct module * module)7801 static struct btf *btf_get_module_btf(const struct module *module)
7802 {
7803 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
7804 struct btf_module *btf_mod, *tmp;
7805 #endif
7806 struct btf *btf = NULL;
7807
7808 if (!module) {
7809 btf = bpf_get_btf_vmlinux();
7810 if (!IS_ERR_OR_NULL(btf))
7811 btf_get(btf);
7812 return btf;
7813 }
7814
7815 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
7816 mutex_lock(&btf_module_mutex);
7817 list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
7818 if (btf_mod->module != module)
7819 continue;
7820
7821 btf_get(btf_mod->btf);
7822 btf = btf_mod->btf;
7823 break;
7824 }
7825 mutex_unlock(&btf_module_mutex);
7826 #endif
7827
7828 return btf;
7829 }
7830
check_btf_kconfigs(const struct module * module,const char * feature)7831 static int check_btf_kconfigs(const struct module *module, const char *feature)
7832 {
7833 if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
7834 pr_err("missing vmlinux BTF, cannot register %s\n", feature);
7835 return -ENOENT;
7836 }
7837 if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
7838 pr_warn("missing module BTF, cannot register %s\n", feature);
7839 return 0;
7840 }
7841
BPF_CALL_4(bpf_btf_find_by_name_kind,char *,name,int,name_sz,u32,kind,int,flags)7842 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
7843 {
7844 struct btf *btf = NULL;
7845 int btf_obj_fd = 0;
7846 long ret;
7847
7848 if (flags)
7849 return -EINVAL;
7850
7851 if (name_sz <= 1 || name[name_sz - 1])
7852 return -EINVAL;
7853
7854 ret = bpf_find_btf_id(name, kind, &btf);
7855 if (ret > 0 && btf_is_module(btf)) {
7856 btf_obj_fd = __btf_new_fd(btf);
7857 if (btf_obj_fd < 0) {
7858 btf_put(btf);
7859 return btf_obj_fd;
7860 }
7861 return ret | (((u64)btf_obj_fd) << 32);
7862 }
7863 if (ret > 0)
7864 btf_put(btf);
7865 return ret;
7866 }
7867
7868 const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
7869 .func = bpf_btf_find_by_name_kind,
7870 .gpl_only = false,
7871 .ret_type = RET_INTEGER,
7872 .arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY,
7873 .arg2_type = ARG_CONST_SIZE,
7874 .arg3_type = ARG_ANYTHING,
7875 .arg4_type = ARG_ANYTHING,
7876 };
7877
BTF_ID_LIST_GLOBAL(btf_tracing_ids,MAX_BTF_TRACING_TYPE)7878 BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE)
7879 #define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type)
7880 BTF_TRACING_TYPE_xxx
7881 #undef BTF_TRACING_TYPE
7882
7883 static int btf_check_iter_kfuncs(struct btf *btf, const char *func_name,
7884 const struct btf_type *func, u32 func_flags)
7885 {
7886 u32 flags = func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY);
7887 const char *name, *sfx, *iter_name;
7888 const struct btf_param *arg;
7889 const struct btf_type *t;
7890 char exp_name[128];
7891 u32 nr_args;
7892
7893 /* exactly one of KF_ITER_{NEW,NEXT,DESTROY} can be set */
7894 if (!flags || (flags & (flags - 1)))
7895 return -EINVAL;
7896
7897 /* any BPF iter kfunc should have `struct bpf_iter_<type> *` first arg */
7898 nr_args = btf_type_vlen(func);
7899 if (nr_args < 1)
7900 return -EINVAL;
7901
7902 arg = &btf_params(func)[0];
7903 t = btf_type_skip_modifiers(btf, arg->type, NULL);
7904 if (!t || !btf_type_is_ptr(t))
7905 return -EINVAL;
7906 t = btf_type_skip_modifiers(btf, t->type, NULL);
7907 if (!t || !__btf_type_is_struct(t))
7908 return -EINVAL;
7909
7910 name = btf_name_by_offset(btf, t->name_off);
7911 if (!name || strncmp(name, ITER_PREFIX, sizeof(ITER_PREFIX) - 1))
7912 return -EINVAL;
7913
7914 /* sizeof(struct bpf_iter_<type>) should be a multiple of 8 to
7915 * fit nicely in stack slots
7916 */
7917 if (t->size == 0 || (t->size % 8))
7918 return -EINVAL;
7919
7920 /* validate bpf_iter_<type>_{new,next,destroy}(struct bpf_iter_<type> *)
7921 * naming pattern
7922 */
7923 iter_name = name + sizeof(ITER_PREFIX) - 1;
7924 if (flags & KF_ITER_NEW)
7925 sfx = "new";
7926 else if (flags & KF_ITER_NEXT)
7927 sfx = "next";
7928 else /* (flags & KF_ITER_DESTROY) */
7929 sfx = "destroy";
7930
7931 snprintf(exp_name, sizeof(exp_name), "bpf_iter_%s_%s", iter_name, sfx);
7932 if (strcmp(func_name, exp_name))
7933 return -EINVAL;
7934
7935 /* only iter constructor should have extra arguments */
7936 if (!(flags & KF_ITER_NEW) && nr_args != 1)
7937 return -EINVAL;
7938
7939 if (flags & KF_ITER_NEXT) {
7940 /* bpf_iter_<type>_next() should return pointer */
7941 t = btf_type_skip_modifiers(btf, func->type, NULL);
7942 if (!t || !btf_type_is_ptr(t))
7943 return -EINVAL;
7944 }
7945
7946 if (flags & KF_ITER_DESTROY) {
7947 /* bpf_iter_<type>_destroy() should return void */
7948 t = btf_type_by_id(btf, func->type);
7949 if (!t || !btf_type_is_void(t))
7950 return -EINVAL;
7951 }
7952
7953 return 0;
7954 }
7955
btf_check_kfunc_protos(struct btf * btf,u32 func_id,u32 func_flags)7956 static int btf_check_kfunc_protos(struct btf *btf, u32 func_id, u32 func_flags)
7957 {
7958 const struct btf_type *func;
7959 const char *func_name;
7960 int err;
7961
7962 /* any kfunc should be FUNC -> FUNC_PROTO */
7963 func = btf_type_by_id(btf, func_id);
7964 if (!func || !btf_type_is_func(func))
7965 return -EINVAL;
7966
7967 /* sanity check kfunc name */
7968 func_name = btf_name_by_offset(btf, func->name_off);
7969 if (!func_name || !func_name[0])
7970 return -EINVAL;
7971
7972 func = btf_type_by_id(btf, func->type);
7973 if (!func || !btf_type_is_func_proto(func))
7974 return -EINVAL;
7975
7976 if (func_flags & (KF_ITER_NEW | KF_ITER_NEXT | KF_ITER_DESTROY)) {
7977 err = btf_check_iter_kfuncs(btf, func_name, func, func_flags);
7978 if (err)
7979 return err;
7980 }
7981
7982 return 0;
7983 }
7984
7985 /* Kernel Function (kfunc) BTF ID set registration API */
7986
btf_populate_kfunc_set(struct btf * btf,enum btf_kfunc_hook hook,const struct btf_kfunc_id_set * kset)7987 static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
7988 const struct btf_kfunc_id_set *kset)
7989 {
7990 struct btf_kfunc_hook_filter *hook_filter;
7991 struct btf_id_set8 *add_set = kset->set;
7992 bool vmlinux_set = !btf_is_module(btf);
7993 bool add_filter = !!kset->filter;
7994 struct btf_kfunc_set_tab *tab;
7995 struct btf_id_set8 *set;
7996 u32 set_cnt;
7997 int ret;
7998
7999 if (hook >= BTF_KFUNC_HOOK_MAX) {
8000 ret = -EINVAL;
8001 goto end;
8002 }
8003
8004 if (!add_set->cnt)
8005 return 0;
8006
8007 tab = btf->kfunc_set_tab;
8008
8009 if (tab && add_filter) {
8010 u32 i;
8011
8012 hook_filter = &tab->hook_filters[hook];
8013 for (i = 0; i < hook_filter->nr_filters; i++) {
8014 if (hook_filter->filters[i] == kset->filter) {
8015 add_filter = false;
8016 break;
8017 }
8018 }
8019
8020 if (add_filter && hook_filter->nr_filters == BTF_KFUNC_FILTER_MAX_CNT) {
8021 ret = -E2BIG;
8022 goto end;
8023 }
8024 }
8025
8026 if (!tab) {
8027 tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
8028 if (!tab)
8029 return -ENOMEM;
8030 btf->kfunc_set_tab = tab;
8031 }
8032
8033 set = tab->sets[hook];
8034 /* Warn when register_btf_kfunc_id_set is called twice for the same hook
8035 * for module sets.
8036 */
8037 if (WARN_ON_ONCE(set && !vmlinux_set)) {
8038 ret = -EINVAL;
8039 goto end;
8040 }
8041
8042 /* We don't need to allocate, concatenate, and sort module sets, because
8043 * only one is allowed per hook. Hence, we can directly assign the
8044 * pointer and return.
8045 */
8046 if (!vmlinux_set) {
8047 tab->sets[hook] = add_set;
8048 goto do_add_filter;
8049 }
8050
8051 /* In case of vmlinux sets, there may be more than one set being
8052 * registered per hook. To create a unified set, we allocate a new set
8053 * and concatenate all individual sets being registered. While each set
8054 * is individually sorted, they may become unsorted when concatenated,
8055 * hence re-sorting the final set again is required to make binary
8056 * searching the set using btf_id_set8_contains function work.
8057 */
8058 set_cnt = set ? set->cnt : 0;
8059
8060 if (set_cnt > U32_MAX - add_set->cnt) {
8061 ret = -EOVERFLOW;
8062 goto end;
8063 }
8064
8065 if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) {
8066 ret = -E2BIG;
8067 goto end;
8068 }
8069
8070 /* Grow set */
8071 set = krealloc(tab->sets[hook],
8072 offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]),
8073 GFP_KERNEL | __GFP_NOWARN);
8074 if (!set) {
8075 ret = -ENOMEM;
8076 goto end;
8077 }
8078
8079 /* For newly allocated set, initialize set->cnt to 0 */
8080 if (!tab->sets[hook])
8081 set->cnt = 0;
8082 tab->sets[hook] = set;
8083
8084 /* Concatenate the two sets */
8085 memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0]));
8086 set->cnt += add_set->cnt;
8087
8088 sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);
8089
8090 do_add_filter:
8091 if (add_filter) {
8092 hook_filter = &tab->hook_filters[hook];
8093 hook_filter->filters[hook_filter->nr_filters++] = kset->filter;
8094 }
8095 return 0;
8096 end:
8097 btf_free_kfunc_set_tab(btf);
8098 return ret;
8099 }
8100
__btf_kfunc_id_set_contains(const struct btf * btf,enum btf_kfunc_hook hook,u32 kfunc_btf_id,const struct bpf_prog * prog)8101 static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
8102 enum btf_kfunc_hook hook,
8103 u32 kfunc_btf_id,
8104 const struct bpf_prog *prog)
8105 {
8106 struct btf_kfunc_hook_filter *hook_filter;
8107 struct btf_id_set8 *set;
8108 u32 *id, i;
8109
8110 if (hook >= BTF_KFUNC_HOOK_MAX)
8111 return NULL;
8112 if (!btf->kfunc_set_tab)
8113 return NULL;
8114 hook_filter = &btf->kfunc_set_tab->hook_filters[hook];
8115 for (i = 0; i < hook_filter->nr_filters; i++) {
8116 if (hook_filter->filters[i](prog, kfunc_btf_id))
8117 return NULL;
8118 }
8119 set = btf->kfunc_set_tab->sets[hook];
8120 if (!set)
8121 return NULL;
8122 id = btf_id_set8_contains(set, kfunc_btf_id);
8123 if (!id)
8124 return NULL;
8125 /* The flags for BTF ID are located next to it */
8126 return id + 1;
8127 }
8128
bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)8129 static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
8130 {
8131 switch (prog_type) {
8132 case BPF_PROG_TYPE_UNSPEC:
8133 return BTF_KFUNC_HOOK_COMMON;
8134 case BPF_PROG_TYPE_XDP:
8135 return BTF_KFUNC_HOOK_XDP;
8136 case BPF_PROG_TYPE_SCHED_CLS:
8137 return BTF_KFUNC_HOOK_TC;
8138 case BPF_PROG_TYPE_STRUCT_OPS:
8139 return BTF_KFUNC_HOOK_STRUCT_OPS;
8140 case BPF_PROG_TYPE_TRACING:
8141 case BPF_PROG_TYPE_LSM:
8142 return BTF_KFUNC_HOOK_TRACING;
8143 case BPF_PROG_TYPE_SYSCALL:
8144 return BTF_KFUNC_HOOK_SYSCALL;
8145 case BPF_PROG_TYPE_CGROUP_SKB:
8146 case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
8147 return BTF_KFUNC_HOOK_CGROUP_SKB;
8148 case BPF_PROG_TYPE_SCHED_ACT:
8149 return BTF_KFUNC_HOOK_SCHED_ACT;
8150 case BPF_PROG_TYPE_SK_SKB:
8151 return BTF_KFUNC_HOOK_SK_SKB;
8152 case BPF_PROG_TYPE_SOCKET_FILTER:
8153 return BTF_KFUNC_HOOK_SOCKET_FILTER;
8154 case BPF_PROG_TYPE_LWT_OUT:
8155 case BPF_PROG_TYPE_LWT_IN:
8156 case BPF_PROG_TYPE_LWT_XMIT:
8157 case BPF_PROG_TYPE_LWT_SEG6LOCAL:
8158 return BTF_KFUNC_HOOK_LWT;
8159 case BPF_PROG_TYPE_NETFILTER:
8160 return BTF_KFUNC_HOOK_NETFILTER;
8161 case BPF_PROG_TYPE_KPROBE:
8162 return BTF_KFUNC_HOOK_KPROBE;
8163 default:
8164 return BTF_KFUNC_HOOK_MAX;
8165 }
8166 }
8167
8168 /* Caution:
8169 * Reference to the module (obtained using btf_try_get_module) corresponding to
8170 * the struct btf *MUST* be held when calling this function from verifier
8171 * context. This is usually true as we stash references in prog's kfunc_btf_tab;
8172 * keeping the reference for the duration of the call provides the necessary
8173 * protection for looking up a well-formed btf->kfunc_set_tab.
8174 */
btf_kfunc_id_set_contains(const struct btf * btf,u32 kfunc_btf_id,const struct bpf_prog * prog)8175 u32 *btf_kfunc_id_set_contains(const struct btf *btf,
8176 u32 kfunc_btf_id,
8177 const struct bpf_prog *prog)
8178 {
8179 enum bpf_prog_type prog_type = resolve_prog_type(prog);
8180 enum btf_kfunc_hook hook;
8181 u32 *kfunc_flags;
8182
8183 kfunc_flags = __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_COMMON, kfunc_btf_id, prog);
8184 if (kfunc_flags)
8185 return kfunc_flags;
8186
8187 hook = bpf_prog_type_to_kfunc_hook(prog_type);
8188 return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id, prog);
8189 }
8190
btf_kfunc_is_modify_return(const struct btf * btf,u32 kfunc_btf_id,const struct bpf_prog * prog)8191 u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id,
8192 const struct bpf_prog *prog)
8193 {
8194 return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, kfunc_btf_id, prog);
8195 }
8196
__register_btf_kfunc_id_set(enum btf_kfunc_hook hook,const struct btf_kfunc_id_set * kset)8197 static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
8198 const struct btf_kfunc_id_set *kset)
8199 {
8200 struct btf *btf;
8201 int ret, i;
8202
8203 btf = btf_get_module_btf(kset->owner);
8204 if (!btf)
8205 return check_btf_kconfigs(kset->owner, "kfunc");
8206 if (IS_ERR(btf))
8207 return PTR_ERR(btf);
8208
8209 for (i = 0; i < kset->set->cnt; i++) {
8210 ret = btf_check_kfunc_protos(btf, kset->set->pairs[i].id,
8211 kset->set->pairs[i].flags);
8212 if (ret)
8213 goto err_out;
8214 }
8215
8216 ret = btf_populate_kfunc_set(btf, hook, kset);
8217
8218 err_out:
8219 btf_put(btf);
8220 return ret;
8221 }
8222
8223 /* This function must be invoked only from initcalls/module init functions */
register_btf_kfunc_id_set(enum bpf_prog_type prog_type,const struct btf_kfunc_id_set * kset)8224 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
8225 const struct btf_kfunc_id_set *kset)
8226 {
8227 enum btf_kfunc_hook hook;
8228
8229 /* All kfuncs need to be tagged as such in BTF.
8230 * WARN() for initcall registrations that do not check errors.
8231 */
8232 if (!(kset->set->flags & BTF_SET8_KFUNCS)) {
8233 WARN_ON(!kset->owner);
8234 return -EINVAL;
8235 }
8236
8237 hook = bpf_prog_type_to_kfunc_hook(prog_type);
8238 return __register_btf_kfunc_id_set(hook, kset);
8239 }
8240 EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
8241
8242 /* This function must be invoked only from initcalls/module init functions */
register_btf_fmodret_id_set(const struct btf_kfunc_id_set * kset)8243 int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset)
8244 {
8245 return __register_btf_kfunc_id_set(BTF_KFUNC_HOOK_FMODRET, kset);
8246 }
8247 EXPORT_SYMBOL_GPL(register_btf_fmodret_id_set);
8248
btf_find_dtor_kfunc(struct btf * btf,u32 btf_id)8249 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
8250 {
8251 struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
8252 struct btf_id_dtor_kfunc *dtor;
8253
8254 if (!tab)
8255 return -ENOENT;
8256 /* Even though the size of tab->dtors[0] is > sizeof(u32), we only need
8257 * to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func.
8258 */
8259 BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0);
8260 dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func);
8261 if (!dtor)
8262 return -ENOENT;
8263 return dtor->kfunc_btf_id;
8264 }
8265
btf_check_dtor_kfuncs(struct btf * btf,const struct btf_id_dtor_kfunc * dtors,u32 cnt)8266 static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt)
8267 {
8268 const struct btf_type *dtor_func, *dtor_func_proto, *t;
8269 const struct btf_param *args;
8270 s32 dtor_btf_id;
8271 u32 nr_args, i;
8272
8273 for (i = 0; i < cnt; i++) {
8274 dtor_btf_id = dtors[i].kfunc_btf_id;
8275
8276 dtor_func = btf_type_by_id(btf, dtor_btf_id);
8277 if (!dtor_func || !btf_type_is_func(dtor_func))
8278 return -EINVAL;
8279
8280 dtor_func_proto = btf_type_by_id(btf, dtor_func->type);
8281 if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto))
8282 return -EINVAL;
8283
8284 /* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
8285 t = btf_type_by_id(btf, dtor_func_proto->type);
8286 if (!t || !btf_type_is_void(t))
8287 return -EINVAL;
8288
8289 nr_args = btf_type_vlen(dtor_func_proto);
8290 if (nr_args != 1)
8291 return -EINVAL;
8292 args = btf_params(dtor_func_proto);
8293 t = btf_type_by_id(btf, args[0].type);
8294 /* Allow any pointer type, as width on targets Linux supports
8295 * will be same for all pointer types (i.e. sizeof(void *))
8296 */
8297 if (!t || !btf_type_is_ptr(t))
8298 return -EINVAL;
8299 }
8300 return 0;
8301 }
8302
8303 /* This function must be invoked only from initcalls/module init functions */
register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc * dtors,u32 add_cnt,struct module * owner)8304 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
8305 struct module *owner)
8306 {
8307 struct btf_id_dtor_kfunc_tab *tab;
8308 struct btf *btf;
8309 u32 tab_cnt;
8310 int ret;
8311
8312 btf = btf_get_module_btf(owner);
8313 if (!btf)
8314 return check_btf_kconfigs(owner, "dtor kfuncs");
8315 if (IS_ERR(btf))
8316 return PTR_ERR(btf);
8317
8318 if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
8319 pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
8320 ret = -E2BIG;
8321 goto end;
8322 }
8323
8324 /* Ensure that the prototype of dtor kfuncs being registered is sane */
8325 ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt);
8326 if (ret < 0)
8327 goto end;
8328
8329 tab = btf->dtor_kfunc_tab;
8330 /* Only one call allowed for modules */
8331 if (WARN_ON_ONCE(tab && btf_is_module(btf))) {
8332 ret = -EINVAL;
8333 goto end;
8334 }
8335
8336 tab_cnt = tab ? tab->cnt : 0;
8337 if (tab_cnt > U32_MAX - add_cnt) {
8338 ret = -EOVERFLOW;
8339 goto end;
8340 }
8341 if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
8342 pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
8343 ret = -E2BIG;
8344 goto end;
8345 }
8346
8347 tab = krealloc(btf->dtor_kfunc_tab,
8348 offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]),
8349 GFP_KERNEL | __GFP_NOWARN);
8350 if (!tab) {
8351 ret = -ENOMEM;
8352 goto end;
8353 }
8354
8355 if (!btf->dtor_kfunc_tab)
8356 tab->cnt = 0;
8357 btf->dtor_kfunc_tab = tab;
8358
8359 memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0]));
8360 tab->cnt += add_cnt;
8361
8362 sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
8363
8364 end:
8365 if (ret)
8366 btf_free_dtor_kfunc_tab(btf);
8367 btf_put(btf);
8368 return ret;
8369 }
8370 EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs);
8371
8372 #define MAX_TYPES_ARE_COMPAT_DEPTH 2
8373
8374 /* Check local and target types for compatibility. This check is used for
8375 * type-based CO-RE relocations and follow slightly different rules than
8376 * field-based relocations. This function assumes that root types were already
8377 * checked for name match. Beyond that initial root-level name check, names
8378 * are completely ignored. Compatibility rules are as follows:
8379 * - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs/ENUM64s are considered compatible, but
8380 * kind should match for local and target types (i.e., STRUCT is not
8381 * compatible with UNION);
8382 * - for ENUMs/ENUM64s, the size is ignored;
8383 * - for INT, size and signedness are ignored;
8384 * - for ARRAY, dimensionality is ignored, element types are checked for
8385 * compatibility recursively;
8386 * - CONST/VOLATILE/RESTRICT modifiers are ignored;
8387 * - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
8388 * - FUNC_PROTOs are compatible if they have compatible signature: same
8389 * number of input args and compatible return and argument types.
8390 * These rules are not set in stone and probably will be adjusted as we get
8391 * more experience with using BPF CO-RE relocations.
8392 */
bpf_core_types_are_compat(const struct btf * local_btf,__u32 local_id,const struct btf * targ_btf,__u32 targ_id)8393 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
8394 const struct btf *targ_btf, __u32 targ_id)
8395 {
8396 return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
8397 MAX_TYPES_ARE_COMPAT_DEPTH);
8398 }
8399
8400 #define MAX_TYPES_MATCH_DEPTH 2
8401
bpf_core_types_match(const struct btf * local_btf,u32 local_id,const struct btf * targ_btf,u32 targ_id)8402 int bpf_core_types_match(const struct btf *local_btf, u32 local_id,
8403 const struct btf *targ_btf, u32 targ_id)
8404 {
8405 return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false,
8406 MAX_TYPES_MATCH_DEPTH);
8407 }
8408
bpf_core_is_flavor_sep(const char * s)8409 static bool bpf_core_is_flavor_sep(const char *s)
8410 {
8411 /* check X___Y name pattern, where X and Y are not underscores */
8412 return s[0] != '_' && /* X */
8413 s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
8414 s[4] != '_'; /* Y */
8415 }
8416
bpf_core_essential_name_len(const char * name)8417 size_t bpf_core_essential_name_len(const char *name)
8418 {
8419 size_t n = strlen(name);
8420 int i;
8421
8422 for (i = n - 5; i >= 0; i--) {
8423 if (bpf_core_is_flavor_sep(name + i))
8424 return i + 1;
8425 }
8426 return n;
8427 }
8428
bpf_free_cands(struct bpf_cand_cache * cands)8429 static void bpf_free_cands(struct bpf_cand_cache *cands)
8430 {
8431 if (!cands->cnt)
8432 /* empty candidate array was allocated on stack */
8433 return;
8434 kfree(cands);
8435 }
8436
bpf_free_cands_from_cache(struct bpf_cand_cache * cands)8437 static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands)
8438 {
8439 kfree(cands->name);
8440 kfree(cands);
8441 }
8442
8443 #define VMLINUX_CAND_CACHE_SIZE 31
8444 static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE];
8445
8446 #define MODULE_CAND_CACHE_SIZE 31
8447 static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE];
8448
__print_cand_cache(struct bpf_verifier_log * log,struct bpf_cand_cache ** cache,int cache_size)8449 static void __print_cand_cache(struct bpf_verifier_log *log,
8450 struct bpf_cand_cache **cache,
8451 int cache_size)
8452 {
8453 struct bpf_cand_cache *cc;
8454 int i, j;
8455
8456 for (i = 0; i < cache_size; i++) {
8457 cc = cache[i];
8458 if (!cc)
8459 continue;
8460 bpf_log(log, "[%d]%s(", i, cc->name);
8461 for (j = 0; j < cc->cnt; j++) {
8462 bpf_log(log, "%d", cc->cands[j].id);
8463 if (j < cc->cnt - 1)
8464 bpf_log(log, " ");
8465 }
8466 bpf_log(log, "), ");
8467 }
8468 }
8469
print_cand_cache(struct bpf_verifier_log * log)8470 static void print_cand_cache(struct bpf_verifier_log *log)
8471 {
8472 mutex_lock(&cand_cache_mutex);
8473 bpf_log(log, "vmlinux_cand_cache:");
8474 __print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
8475 bpf_log(log, "\nmodule_cand_cache:");
8476 __print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE);
8477 bpf_log(log, "\n");
8478 mutex_unlock(&cand_cache_mutex);
8479 }
8480
hash_cands(struct bpf_cand_cache * cands)8481 static u32 hash_cands(struct bpf_cand_cache *cands)
8482 {
8483 return jhash(cands->name, cands->name_len, 0);
8484 }
8485
check_cand_cache(struct bpf_cand_cache * cands,struct bpf_cand_cache ** cache,int cache_size)8486 static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands,
8487 struct bpf_cand_cache **cache,
8488 int cache_size)
8489 {
8490 struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size];
8491
8492 if (cc && cc->name_len == cands->name_len &&
8493 !strncmp(cc->name, cands->name, cands->name_len))
8494 return cc;
8495 return NULL;
8496 }
8497
sizeof_cands(int cnt)8498 static size_t sizeof_cands(int cnt)
8499 {
8500 return offsetof(struct bpf_cand_cache, cands[cnt]);
8501 }
8502
populate_cand_cache(struct bpf_cand_cache * cands,struct bpf_cand_cache ** cache,int cache_size)8503 static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
8504 struct bpf_cand_cache **cache,
8505 int cache_size)
8506 {
8507 struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands;
8508
8509 if (*cc) {
8510 bpf_free_cands_from_cache(*cc);
8511 *cc = NULL;
8512 }
8513 new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
8514 if (!new_cands) {
8515 bpf_free_cands(cands);
8516 return ERR_PTR(-ENOMEM);
8517 }
8518 /* strdup the name, since it will stay in cache.
8519 * the cands->name points to strings in prog's BTF and the prog can be unloaded.
8520 */
8521 new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
8522 bpf_free_cands(cands);
8523 if (!new_cands->name) {
8524 kfree(new_cands);
8525 return ERR_PTR(-ENOMEM);
8526 }
8527 *cc = new_cands;
8528 return new_cands;
8529 }
8530
8531 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
__purge_cand_cache(struct btf * btf,struct bpf_cand_cache ** cache,int cache_size)8532 static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache,
8533 int cache_size)
8534 {
8535 struct bpf_cand_cache *cc;
8536 int i, j;
8537
8538 for (i = 0; i < cache_size; i++) {
8539 cc = cache[i];
8540 if (!cc)
8541 continue;
8542 if (!btf) {
8543 /* when new module is loaded purge all of module_cand_cache,
8544 * since new module might have candidates with the name
8545 * that matches cached cands.
8546 */
8547 bpf_free_cands_from_cache(cc);
8548 cache[i] = NULL;
8549 continue;
8550 }
8551 /* when module is unloaded purge cache entries
8552 * that match module's btf
8553 */
8554 for (j = 0; j < cc->cnt; j++)
8555 if (cc->cands[j].btf == btf) {
8556 bpf_free_cands_from_cache(cc);
8557 cache[i] = NULL;
8558 break;
8559 }
8560 }
8561
8562 }
8563
purge_cand_cache(struct btf * btf)8564 static void purge_cand_cache(struct btf *btf)
8565 {
8566 mutex_lock(&cand_cache_mutex);
8567 __purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE);
8568 mutex_unlock(&cand_cache_mutex);
8569 }
8570 #endif
8571
8572 static struct bpf_cand_cache *
bpf_core_add_cands(struct bpf_cand_cache * cands,const struct btf * targ_btf,int targ_start_id)8573 bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
8574 int targ_start_id)
8575 {
8576 struct bpf_cand_cache *new_cands;
8577 const struct btf_type *t;
8578 const char *targ_name;
8579 size_t targ_essent_len;
8580 int n, i;
8581
8582 n = btf_nr_types(targ_btf);
8583 for (i = targ_start_id; i < n; i++) {
8584 t = btf_type_by_id(targ_btf, i);
8585 if (btf_kind(t) != cands->kind)
8586 continue;
8587
8588 targ_name = btf_name_by_offset(targ_btf, t->name_off);
8589 if (!targ_name)
8590 continue;
8591
8592 /* the resched point is before strncmp to make sure that search
8593 * for non-existing name will have a chance to schedule().
8594 */
8595 cond_resched();
8596
8597 if (strncmp(cands->name, targ_name, cands->name_len) != 0)
8598 continue;
8599
8600 targ_essent_len = bpf_core_essential_name_len(targ_name);
8601 if (targ_essent_len != cands->name_len)
8602 continue;
8603
8604 /* most of the time there is only one candidate for a given kind+name pair */
8605 new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
8606 if (!new_cands) {
8607 bpf_free_cands(cands);
8608 return ERR_PTR(-ENOMEM);
8609 }
8610
8611 memcpy(new_cands, cands, sizeof_cands(cands->cnt));
8612 bpf_free_cands(cands);
8613 cands = new_cands;
8614 cands->cands[cands->cnt].btf = targ_btf;
8615 cands->cands[cands->cnt].id = i;
8616 cands->cnt++;
8617 }
8618 return cands;
8619 }
8620
8621 static struct bpf_cand_cache *
bpf_core_find_cands(struct bpf_core_ctx * ctx,u32 local_type_id)8622 bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
8623 {
8624 struct bpf_cand_cache *cands, *cc, local_cand = {};
8625 const struct btf *local_btf = ctx->btf;
8626 const struct btf_type *local_type;
8627 const struct btf *main_btf;
8628 size_t local_essent_len;
8629 struct btf *mod_btf;
8630 const char *name;
8631 int id;
8632
8633 main_btf = bpf_get_btf_vmlinux();
8634 if (IS_ERR(main_btf))
8635 return ERR_CAST(main_btf);
8636 if (!main_btf)
8637 return ERR_PTR(-EINVAL);
8638
8639 local_type = btf_type_by_id(local_btf, local_type_id);
8640 if (!local_type)
8641 return ERR_PTR(-EINVAL);
8642
8643 name = btf_name_by_offset(local_btf, local_type->name_off);
8644 if (str_is_empty(name))
8645 return ERR_PTR(-EINVAL);
8646 local_essent_len = bpf_core_essential_name_len(name);
8647
8648 cands = &local_cand;
8649 cands->name = name;
8650 cands->kind = btf_kind(local_type);
8651 cands->name_len = local_essent_len;
8652
8653 cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
8654 /* cands is a pointer to stack here */
8655 if (cc) {
8656 if (cc->cnt)
8657 return cc;
8658 goto check_modules;
8659 }
8660
8661 /* Attempt to find target candidates in vmlinux BTF first */
8662 cands = bpf_core_add_cands(cands, main_btf, 1);
8663 if (IS_ERR(cands))
8664 return ERR_CAST(cands);
8665
8666 /* cands is a pointer to kmalloced memory here if cands->cnt > 0 */
8667
8668 /* populate cache even when cands->cnt == 0 */
8669 cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
8670 if (IS_ERR(cc))
8671 return ERR_CAST(cc);
8672
8673 /* if vmlinux BTF has any candidate, don't go for module BTFs */
8674 if (cc->cnt)
8675 return cc;
8676
8677 check_modules:
8678 /* cands is a pointer to stack here and cands->cnt == 0 */
8679 cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
8680 if (cc)
8681 /* if cache has it return it even if cc->cnt == 0 */
8682 return cc;
8683
8684 /* If candidate is not found in vmlinux's BTF then search in module's BTFs */
8685 spin_lock_bh(&btf_idr_lock);
8686 idr_for_each_entry(&btf_idr, mod_btf, id) {
8687 if (!btf_is_module(mod_btf))
8688 continue;
8689 /* linear search could be slow hence unlock/lock
8690 * the IDR to avoiding holding it for too long
8691 */
8692 btf_get(mod_btf);
8693 spin_unlock_bh(&btf_idr_lock);
8694 cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
8695 btf_put(mod_btf);
8696 if (IS_ERR(cands))
8697 return ERR_CAST(cands);
8698 spin_lock_bh(&btf_idr_lock);
8699 }
8700 spin_unlock_bh(&btf_idr_lock);
8701 /* cands is a pointer to kmalloced memory here if cands->cnt > 0
8702 * or pointer to stack if cands->cnd == 0.
8703 * Copy it into the cache even when cands->cnt == 0 and
8704 * return the result.
8705 */
8706 return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
8707 }
8708
bpf_core_apply(struct bpf_core_ctx * ctx,const struct bpf_core_relo * relo,int relo_idx,void * insn)8709 int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
8710 int relo_idx, void *insn)
8711 {
8712 bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL;
8713 struct bpf_core_cand_list cands = {};
8714 struct bpf_core_relo_res targ_res;
8715 struct bpf_core_spec *specs;
8716 int err;
8717
8718 /* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
8719 * into arrays of btf_ids of struct fields and array indices.
8720 */
8721 specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
8722 if (!specs)
8723 return -ENOMEM;
8724
8725 if (need_cands) {
8726 struct bpf_cand_cache *cc;
8727 int i;
8728
8729 mutex_lock(&cand_cache_mutex);
8730 cc = bpf_core_find_cands(ctx, relo->type_id);
8731 if (IS_ERR(cc)) {
8732 bpf_log(ctx->log, "target candidate search failed for %d\n",
8733 relo->type_id);
8734 err = PTR_ERR(cc);
8735 goto out;
8736 }
8737 if (cc->cnt) {
8738 cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
8739 if (!cands.cands) {
8740 err = -ENOMEM;
8741 goto out;
8742 }
8743 }
8744 for (i = 0; i < cc->cnt; i++) {
8745 bpf_log(ctx->log,
8746 "CO-RE relocating %s %s: found target candidate [%d]\n",
8747 btf_kind_str[cc->kind], cc->name, cc->cands[i].id);
8748 cands.cands[i].btf = cc->cands[i].btf;
8749 cands.cands[i].id = cc->cands[i].id;
8750 }
8751 cands.len = cc->cnt;
8752 /* cand_cache_mutex needs to span the cache lookup and
8753 * copy of btf pointer into bpf_core_cand_list,
8754 * since module can be unloaded while bpf_core_calc_relo_insn
8755 * is working with module's btf.
8756 */
8757 }
8758
8759 err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs,
8760 &targ_res);
8761 if (err)
8762 goto out;
8763
8764 err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx,
8765 &targ_res);
8766
8767 out:
8768 kfree(specs);
8769 if (need_cands) {
8770 kfree(cands.cands);
8771 mutex_unlock(&cand_cache_mutex);
8772 if (ctx->log->level & BPF_LOG_LEVEL2)
8773 print_cand_cache(ctx->log);
8774 }
8775 return err;
8776 }
8777
btf_nested_type_is_trusted(struct bpf_verifier_log * log,const struct bpf_reg_state * reg,const char * field_name,u32 btf_id,const char * suffix)8778 bool btf_nested_type_is_trusted(struct bpf_verifier_log *log,
8779 const struct bpf_reg_state *reg,
8780 const char *field_name, u32 btf_id, const char *suffix)
8781 {
8782 struct btf *btf = reg->btf;
8783 const struct btf_type *walk_type, *safe_type;
8784 const char *tname;
8785 char safe_tname[64];
8786 long ret, safe_id;
8787 const struct btf_member *member;
8788 u32 i;
8789
8790 walk_type = btf_type_by_id(btf, reg->btf_id);
8791 if (!walk_type)
8792 return false;
8793
8794 tname = btf_name_by_offset(btf, walk_type->name_off);
8795
8796 ret = snprintf(safe_tname, sizeof(safe_tname), "%s%s", tname, suffix);
8797 if (ret >= sizeof(safe_tname))
8798 return false;
8799
8800 safe_id = btf_find_by_name_kind(btf, safe_tname, BTF_INFO_KIND(walk_type->info));
8801 if (safe_id < 0)
8802 return false;
8803
8804 safe_type = btf_type_by_id(btf, safe_id);
8805 if (!safe_type)
8806 return false;
8807
8808 for_each_member(i, safe_type, member) {
8809 const char *m_name = __btf_name_by_offset(btf, member->name_off);
8810 const struct btf_type *mtype = btf_type_by_id(btf, member->type);
8811 u32 id;
8812
8813 if (!btf_type_is_ptr(mtype))
8814 continue;
8815
8816 btf_type_skip_modifiers(btf, mtype->type, &id);
8817 /* If we match on both type and name, the field is considered trusted. */
8818 if (btf_id == id && !strcmp(field_name, m_name))
8819 return true;
8820 }
8821
8822 return false;
8823 }
8824
btf_type_ids_nocast_alias(struct bpf_verifier_log * log,const struct btf * reg_btf,u32 reg_id,const struct btf * arg_btf,u32 arg_id)8825 bool btf_type_ids_nocast_alias(struct bpf_verifier_log *log,
8826 const struct btf *reg_btf, u32 reg_id,
8827 const struct btf *arg_btf, u32 arg_id)
8828 {
8829 const char *reg_name, *arg_name, *search_needle;
8830 const struct btf_type *reg_type, *arg_type;
8831 int reg_len, arg_len, cmp_len;
8832 size_t pattern_len = sizeof(NOCAST_ALIAS_SUFFIX) - sizeof(char);
8833
8834 reg_type = btf_type_by_id(reg_btf, reg_id);
8835 if (!reg_type)
8836 return false;
8837
8838 arg_type = btf_type_by_id(arg_btf, arg_id);
8839 if (!arg_type)
8840 return false;
8841
8842 reg_name = btf_name_by_offset(reg_btf, reg_type->name_off);
8843 arg_name = btf_name_by_offset(arg_btf, arg_type->name_off);
8844
8845 reg_len = strlen(reg_name);
8846 arg_len = strlen(arg_name);
8847
8848 /* Exactly one of the two type names may be suffixed with ___init, so
8849 * if the strings are the same size, they can't possibly be no-cast
8850 * aliases of one another. If you have two of the same type names, e.g.
8851 * they're both nf_conn___init, it would be improper to return true
8852 * because they are _not_ no-cast aliases, they are the same type.
8853 */
8854 if (reg_len == arg_len)
8855 return false;
8856
8857 /* Either of the two names must be the other name, suffixed with ___init. */
8858 if ((reg_len != arg_len + pattern_len) &&
8859 (arg_len != reg_len + pattern_len))
8860 return false;
8861
8862 if (reg_len < arg_len) {
8863 search_needle = strstr(arg_name, NOCAST_ALIAS_SUFFIX);
8864 cmp_len = reg_len;
8865 } else {
8866 search_needle = strstr(reg_name, NOCAST_ALIAS_SUFFIX);
8867 cmp_len = arg_len;
8868 }
8869
8870 if (!search_needle)
8871 return false;
8872
8873 /* ___init suffix must come at the end of the name */
8874 if (*(search_needle + pattern_len) != '\0')
8875 return false;
8876
8877 return !strncmp(reg_name, arg_name, cmp_len);
8878 }
8879
8880 #ifdef CONFIG_BPF_JIT
8881 static int
btf_add_struct_ops(struct btf * btf,struct bpf_struct_ops * st_ops,struct bpf_verifier_log * log)8882 btf_add_struct_ops(struct btf *btf, struct bpf_struct_ops *st_ops,
8883 struct bpf_verifier_log *log)
8884 {
8885 struct btf_struct_ops_tab *tab, *new_tab;
8886 int i, err;
8887
8888 tab = btf->struct_ops_tab;
8889 if (!tab) {
8890 tab = kzalloc(offsetof(struct btf_struct_ops_tab, ops[4]),
8891 GFP_KERNEL);
8892 if (!tab)
8893 return -ENOMEM;
8894 tab->capacity = 4;
8895 btf->struct_ops_tab = tab;
8896 }
8897
8898 for (i = 0; i < tab->cnt; i++)
8899 if (tab->ops[i].st_ops == st_ops)
8900 return -EEXIST;
8901
8902 if (tab->cnt == tab->capacity) {
8903 new_tab = krealloc(tab,
8904 offsetof(struct btf_struct_ops_tab,
8905 ops[tab->capacity * 2]),
8906 GFP_KERNEL);
8907 if (!new_tab)
8908 return -ENOMEM;
8909 tab = new_tab;
8910 tab->capacity *= 2;
8911 btf->struct_ops_tab = tab;
8912 }
8913
8914 tab->ops[btf->struct_ops_tab->cnt].st_ops = st_ops;
8915
8916 err = bpf_struct_ops_desc_init(&tab->ops[btf->struct_ops_tab->cnt], btf, log);
8917 if (err)
8918 return err;
8919
8920 btf->struct_ops_tab->cnt++;
8921
8922 return 0;
8923 }
8924
8925 const struct bpf_struct_ops_desc *
bpf_struct_ops_find_value(struct btf * btf,u32 value_id)8926 bpf_struct_ops_find_value(struct btf *btf, u32 value_id)
8927 {
8928 const struct bpf_struct_ops_desc *st_ops_list;
8929 unsigned int i;
8930 u32 cnt;
8931
8932 if (!value_id)
8933 return NULL;
8934 if (!btf->struct_ops_tab)
8935 return NULL;
8936
8937 cnt = btf->struct_ops_tab->cnt;
8938 st_ops_list = btf->struct_ops_tab->ops;
8939 for (i = 0; i < cnt; i++) {
8940 if (st_ops_list[i].value_id == value_id)
8941 return &st_ops_list[i];
8942 }
8943
8944 return NULL;
8945 }
8946
8947 const struct bpf_struct_ops_desc *
bpf_struct_ops_find(struct btf * btf,u32 type_id)8948 bpf_struct_ops_find(struct btf *btf, u32 type_id)
8949 {
8950 const struct bpf_struct_ops_desc *st_ops_list;
8951 unsigned int i;
8952 u32 cnt;
8953
8954 if (!type_id)
8955 return NULL;
8956 if (!btf->struct_ops_tab)
8957 return NULL;
8958
8959 cnt = btf->struct_ops_tab->cnt;
8960 st_ops_list = btf->struct_ops_tab->ops;
8961 for (i = 0; i < cnt; i++) {
8962 if (st_ops_list[i].type_id == type_id)
8963 return &st_ops_list[i];
8964 }
8965
8966 return NULL;
8967 }
8968
__register_bpf_struct_ops(struct bpf_struct_ops * st_ops)8969 int __register_bpf_struct_ops(struct bpf_struct_ops *st_ops)
8970 {
8971 struct bpf_verifier_log *log;
8972 struct btf *btf;
8973 int err = 0;
8974
8975 btf = btf_get_module_btf(st_ops->owner);
8976 if (!btf)
8977 return check_btf_kconfigs(st_ops->owner, "struct_ops");
8978 if (IS_ERR(btf))
8979 return PTR_ERR(btf);
8980
8981 log = kzalloc(sizeof(*log), GFP_KERNEL | __GFP_NOWARN);
8982 if (!log) {
8983 err = -ENOMEM;
8984 goto errout;
8985 }
8986
8987 log->level = BPF_LOG_KERNEL;
8988
8989 err = btf_add_struct_ops(btf, st_ops, log);
8990
8991 errout:
8992 kfree(log);
8993 btf_put(btf);
8994
8995 return err;
8996 }
8997 EXPORT_SYMBOL_GPL(__register_bpf_struct_ops);
8998 #endif
8999
btf_param_match_suffix(const struct btf * btf,const struct btf_param * arg,const char * suffix)9000 bool btf_param_match_suffix(const struct btf *btf,
9001 const struct btf_param *arg,
9002 const char *suffix)
9003 {
9004 int suffix_len = strlen(suffix), len;
9005 const char *param_name;
9006
9007 /* In the future, this can be ported to use BTF tagging */
9008 param_name = btf_name_by_offset(btf, arg->name_off);
9009 if (str_is_empty(param_name))
9010 return false;
9011 len = strlen(param_name);
9012 if (len <= suffix_len)
9013 return false;
9014 param_name += len - suffix_len;
9015 return !strncmp(param_name, suffix, suffix_len);
9016 }
9017