1 /* $NetBSD: rtld.h,v 1.146 2023/06/04 01:24:56 joerg Exp $ */
2
3 /*
4 * Copyright 1996 John D. Polstra.
5 * Copyright 1996 Matt Thomas <matt@3am-software.com>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by John Polstra.
19 * 4. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #ifndef RTLD_H
35 #define RTLD_H
36
37 #include <dlfcn.h>
38 #include <signal.h>
39 #include <stdbool.h>
40 #include <stddef.h>
41 #include <sys/param.h>
42 #include <sys/types.h>
43 #include <sys/queue.h>
44 #include <sys/exec_elf.h>
45 #include <sys/tls.h>
46 #include "rtldenv.h"
47 #include "link.h"
48
49 #if defined(_RTLD_SOURCE)
50
51 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
52 #include "unwind.h"
53 #endif
54
55 #ifndef RTLD_DEFAULT_LIBRARY_PATH
56 #define RTLD_DEFAULT_LIBRARY_PATH "/usr/lib"
57 #endif
58 #define _PATH_LD_HINTS "/etc/ld.so.conf"
59
60 extern size_t _rtld_pagesz;
61
62 #define round_down(x) ((x) & ~(_rtld_pagesz - 1))
63 #define round_up(x) round_down((x) + _rtld_pagesz - 1)
64
65 #define NEW(type) ((type *) xmalloc(sizeof(type)))
66 #define CNEW(type) ((type *) xcalloc(sizeof(type)))
67
68 /*
69 * Fill in a DoneList with an allocation large enough to hold all of
70 * the currently-loaded objects. Keep this in a macro since it calls
71 * alloca and we want that to occur within the scope of the caller.
72 */
73 #define _rtld_donelist_init(dlp) \
74 ((dlp)->num_alloc = _rtld_objcount, \
75 (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])), \
76 assert((dlp)->objs != NULL), \
77 (dlp)->num_used = 0)
78
79
80 typedef struct Struct_Elf_Hash {
81 unsigned long sysv;
82 unsigned long gnu;
83 } Elf_Hash;
84 #endif /* _RTLD_SOURCE */
85
86 /*
87 * C++ has mandated the use of the following keywords for its new boolean
88 * type. We might as well follow their lead.
89 */
90 struct Struct_Obj_Entry;
91
92 typedef struct Struct_Objlist_Entry {
93 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
94 struct Struct_Obj_Entry *obj;
95 } Objlist_Entry;
96
97 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
98
99 typedef struct Struct_Name_Entry {
100 SIMPLEQ_ENTRY(Struct_Name_Entry) link;
101 char name[1];
102 } Name_Entry;
103
104 typedef struct Struct_Needed_Entry {
105 struct Struct_Needed_Entry *next;
106 struct Struct_Obj_Entry *obj;
107 unsigned long name; /* Offset of name in string table */
108 } Needed_Entry;
109
110 typedef struct _rtld_search_path_t {
111 struct _rtld_search_path_t *sp_next;
112 const char *sp_path;
113 size_t sp_pathlen;
114 } Search_Path;
115
116 typedef struct Struct_Ver_Entry {
117 Elf_Word hash;
118 u_int flags;
119 const char *name;
120 const char *file;
121 } Ver_Entry;
122
123 /* Ver_Entry.flags */
124 #define VER_INFO_HIDDEN 0x01
125
126 #define RTLD_MAX_ENTRY 10
127 #define RTLD_MAX_LIBRARY 4
128 #define RTLD_MAX_CTL 2
129 typedef struct _rtld_library_xform_t {
130 struct _rtld_library_xform_t *next;
131 char *name;
132 const char *ctlname;
133 struct {
134 char *value;
135 char *library[RTLD_MAX_LIBRARY];
136 } entry[RTLD_MAX_ENTRY];
137 } Library_Xform;
138
139 /*
140 * Shared object descriptor.
141 *
142 * Items marked with "(%)" are dynamically allocated, and must be freed
143 * when the structure is destroyed.
144 */
145
146 typedef void (*fptr_t)(void);
147
148 typedef struct Struct_Obj_Entry {
149 struct Struct_Obj_Entry *next;
150 char *path; /* Pathname of underlying file (%) */
151 int refcount;
152 int dl_refcount; /* Number of times loaded by dlopen */
153
154 /* These items are computed by map_object() or by digest_phdr(). */
155 caddr_t mapbase; /* Base address of mapped region */
156 size_t mapsize; /* Size of mapped region in bytes */
157 size_t textsize; /* Size of text segment in bytes */
158 Elf_Addr vaddrbase; /* Base address in shared object file */
159 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */
160 Elf_Dyn *dynamic; /* Dynamic section */
161 caddr_t entry; /* Entry point */
162 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */
163 size_t phsize; /* Size of program header in bytes */
164
165 /* Items from the dynamic section. */
166 Elf_Addr *pltgot; /* PLTGOT table */
167 const Elf_Rel *rel; /* Relocation entries */
168 const Elf_Rel *rellim; /* Limit of Relocation entries */
169 const Elf_Rela *rela; /* Relocation entries */
170 const Elf_Rela *relalim; /* Limit of Relocation entries */
171 const Elf_Rel *pltrel; /* PLT relocation entries */
172 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */
173 const Elf_Rela *pltrela; /* PLT relocation entries */
174 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */
175 const Elf_Sym *symtab; /* Symbol table */
176 const char *strtab; /* String table */
177 unsigned long strsize; /* Size in bytes of string table */
178 #if defined(__mips__) || defined(__riscv__)
179 Elf_Word local_gotno; /* Number of local GOT entries */
180 Elf_Word symtabno; /* Number of dynamic symbols */
181 Elf_Word gotsym; /* First dynamic symbol in GOT */
182 #endif
183
184 /* SysV Hash fields */
185 const Elf_Symindx *buckets; /* Hash table buckets array */
186 unsigned long unused1; /* Used to be nbuckets */
187 const Elf_Symindx *chains; /* Hash table chain array */
188 unsigned long nchains; /* Number of chains */
189
190 Search_Path *rpaths; /* Search path specified in object */
191 Needed_Entry *needed; /* Shared objects needed by this (%) */
192
193 fptr_t init; /* Initialization function to call */
194 fptr_t fini; /* Termination function to call */
195
196 u_int32_t mainprog:1, /* True if this is the main program */
197 rtld:1, /* True if this is the dynamic linker */
198 textrel:1, /* True if there are relocations to
199 * text seg */
200 symbolic:1, /* True if generated with
201 * "-Bsymbolic" */
202 printed:1, /* True if ldd has printed it */
203 isdynamic:1, /* True if this is a pure PIC object */
204 mainref:1, /* True if on _rtld_list_main */
205 globalref:1, /* True if on _rtld_list_global */
206 init_done:1, /* True if .init has been added */
207 init_called:1, /* True if .init function has been
208 * called */
209 fini_called:1, /* True if .fini function has been
210 * called */
211 z_now:1, /* True if object's symbols should be
212 bound immediately */
213 z_nodelete:1, /* True if object should never be
214 unloaded */
215 z_initfirst:1, /* True if object's .init/.fini take
216 * priority over others */
217 z_noopen:1, /* True if object should never be
218 dlopen'ed */
219 phdr_loaded:1, /* Phdr is loaded and doesn't need to
220 * be freed. */
221 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
222 tls_static:1, /* True if static TLS offset
223 * has been allocated */
224 tls_dynamic:1, /* True if any non-static DTV entry
225 * has been allocated */
226 #endif
227 ref_nodel:1, /* Refcount increased to prevent dlclose */
228 sysv_hash:1, /* SysV Hash available */
229 gnu_hash:1; /* GNU Hash available */
230
231 struct link_map linkmap; /* for the debugger */
232
233 /* These items are computed by map_object() or by digest_phdr(). */
234 const char *interp; /* Pathname of the interpreter, if any */
235 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
236 Objlist dagmembers; /* DAG has these members (%) */
237 dev_t dev; /* Object's filesystem's device */
238 ino_t ino; /* Object's inode number */
239
240 void *ehdr;
241
242 /* SysV Hash fields */
243 uint32_t nbuckets; /* Number of buckets */
244 uint32_t nbuckets_m; /* Precomputed for fast remainder */
245 uint8_t nbuckets_s1;
246 uint8_t nbuckets_s2;
247
248 /* GNU Hash fields */
249 const uint32_t *buckets_gnu; /* Hash table buckets array */
250 uint32_t nbuckets_gnu; /* Number of GNU hash buckets */
251 uint32_t nbuckets_m_gnu; /* Precomputed for fast remainder */
252 uint8_t nbuckets_s1_gnu;
253 uint8_t nbuckets_s2_gnu;
254 const uint32_t *chains_gnu; /* Hash table chain array */
255 #define nchains_gnu nchains /* Number of symbols, shared with SysV Hash */
256 const Elf_Addr *bloom_gnu;
257 uint32_t symndx_gnu; /* First accessible symbol on dynsym table */
258 uint32_t mask_bm_gnu; /* Bloom filter words - 1 (bitmask) */
259 uint32_t shift2_gnu; /* Bloom filter shift count */
260
261 size_t pathlen; /* Pathname length */
262 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this
263 * object we know about. */
264
265 #ifdef __powerpc__
266 #ifdef _LP64
267 Elf_Addr glink; /* global linkage */
268 #else
269 Elf_Addr *gotptr; /* GOT table (secure-plt only) */
270 #endif
271 #endif
272
273 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
274 /* Thread Local Storage support for this module */
275 size_t tlsindex; /* Index in DTV */
276 void *tlsinit; /* Base address of TLS init block */
277 size_t tlsinitsize; /* Size of TLS init block */
278 size_t tlssize; /* Size of TLS block */
279 size_t tlsoffset; /* Offset in the static TLS block */
280 size_t tlsalign; /* Needed alignment for static TLS */
281 #endif
282
283 #ifdef GNU_RELRO
284 /* relocation readonly */
285 void *relro_page;
286 size_t relro_size;
287 #endif
288
289 /* symbol versioning */
290 const Elf_Verneed *verneed; /* Required versions. */
291 Elf_Word verneednum; /* Number of entries in verneed table */
292 const Elf_Verdef *verdef; /* Provided versions. */
293 Elf_Word verdefnum; /* Number of entries in verdef table */
294 const Elf_Versym *versyms; /* Symbol versions table */
295
296 Ver_Entry *vertab; /* Versions required/defined by this
297 * object */
298 int vertabnum; /* Number of entries in vertab */
299
300 /* init_array/fini_array */
301 fptr_t *init_array; /* start of init array */
302 size_t init_arraysz; /* # of entries in it */
303 fptr_t *fini_array; /* start of fini array */
304 size_t fini_arraysz; /* # of entries in it */
305 /* IRELATIVE relocations */
306 size_t ifunc_remaining;
307 #if \
308 defined(__aarch64__) || \
309 defined(__arm__) || \
310 defined(__i386__) || \
311 defined(__powerpc__) || \
312 defined(__sparc__) || \
313 defined(__x86_64__)
314 #define IFUNC_NONPLT
315 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */
316 size_t ifunc_remaining_nonplt;
317 #endif
318 size_t cxa_refcount; /* For TLS destructors. */
319 #ifdef __ARM_EABI__
320 void *exidx_start;
321 size_t exidx_sz;
322 #endif
323 } Obj_Entry;
324
325 typedef struct Struct_DoneList {
326 const Obj_Entry **objs; /* Array of object pointers */
327 unsigned int num_alloc; /* Allocated size of the array */
328 unsigned int num_used; /* Number of array slots used */
329 } DoneList;
330
331
332 #if defined(_RTLD_SOURCE)
333
334 extern struct r_debug _rtld_debug;
335 extern Search_Path *_rtld_default_paths;
336 extern Obj_Entry *_rtld_objlist;
337 extern Obj_Entry **_rtld_objtail;
338 extern u_int _rtld_objcount;
339 extern u_int _rtld_objloads;
340 extern const uintptr_t _rtld_compat_obj[];
341 extern Obj_Entry *_rtld_objmain;
342 extern Obj_Entry _rtld_objself;
343 extern Search_Path *_rtld_paths;
344 extern Library_Xform *_rtld_xforms;
345 extern bool _rtld_trust;
346 extern Objlist _rtld_list_global;
347 extern Objlist _rtld_list_main;
348 extern Elf_Sym _rtld_sym_zero;
349 extern u_int _rtld_objgen;
350
351 #define RTLD_MODEMASK 0x3
352
353 /* Flags to be passed into _rtld_symlook_ family of functions. */
354 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
355 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol.
356 Used by dlsym. */
357
358 /* Flags for _rtld_load_object() and friends. */
359 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */
360 #define _RTLD_MAIN 0x02
361 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */
362 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */
363
364 /* Preallocation for static TLS model */
365 #define RTLD_STATIC_TLS_RESERVATION 64
366
367 /* rtld.c */
368 __dso_public char *dlerror(void);
369 __dso_public void *dlopen(const char *, int);
370 __dso_public void *dlsym(void *, const char *);
371 __dso_public int dlclose(void *);
372 __dso_public int dladdr(const void *, Dl_info *);
373 __dso_public int dlinfo(void *, int, void *);
374 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *),
375 void *);
376
377 __dso_public void *_dlauxinfo(void) __pure;
378 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta);
379
380 __dso_public pid_t __locked_fork(int *);
381
382 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
383 /*
384 * This is used by libgcc to find the start and length of the exception table
385 * associated with a PC.
386 */
387 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *);
388 #endif
389
390 /* These aren't exported */
391 void _rtld_error(const char *, ...) __printflike(1,2);
392 void _rtld_die(void) __dead;
393 void *_rtld_objmain_sym(const char *);
394 __dso_public void _rtld_debug_state(void) __noinline;
395 void _rtld_linkmap_add(Obj_Entry *);
396 void _rtld_linkmap_delete(Obj_Entry *);
397 void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
398 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
399 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
400 void _rtld_ref_dag(Obj_Entry *);
401
402 void _rtld_shared_enter(void);
403 void _rtld_shared_exit(void);
404 void _rtld_exclusive_enter(sigset_t *);
405 void _rtld_exclusive_exit(sigset_t *);
406
407 int _rtld_relro(const Obj_Entry *, bool);
408
409 /* expand.c */
410 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
411 const char *);
412
413 /* headers.c */
414 void _rtld_digest_dynamic(const char *, Obj_Entry *);
415 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
416
417 /* load.c */
418 Obj_Entry *_rtld_load_object(const char *, int);
419 int _rtld_load_needed_objects(Obj_Entry *, int);
420 int _rtld_preload(const char *);
421
422 #define OBJ_ERR (Obj_Entry *)(-1)
423 /* path.c */
424 void _rtld_add_paths(const char *, Search_Path **, const char *);
425 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
426 const char *);
427 int _rtld_sysctl(const char *, void *, size_t *);
428
429 /* reloc.c */
430 int _rtld_do_copy_relocations(const Obj_Entry *);
431 int _rtld_relocate_objects(Obj_Entry *, bool);
432 int _rtld_relocate_nonplt_objects(Obj_Entry *);
433 int _rtld_relocate_plt_lazy(Obj_Entry *);
434 int _rtld_relocate_plt_objects(const Obj_Entry *);
435 void _rtld_setup_pltgot(const Obj_Entry *);
436 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *);
437 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr);
438
439 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int);
440
441 /* search.c */
442 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
443
444 /* symbol.c */
445 Elf32_Word _rtld_sysv_hash(const char *);
446 Elf32_Word _rtld_gnu_hash(const char *);
447 const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *,
448 const Obj_Entry *, u_int, const Ver_Entry *);
449 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
450 const Obj_Entry **, u_int);
451 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
452 const Obj_Entry **, bool);
453
454 const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *,
455 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *);
456 const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *,
457 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *);
458 const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *,
459 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *,
460 DoneList *, DoneList *);
461
462 /* symver.c */
463 void _rtld_object_add_name(Obj_Entry *, const char *);
464 int _rtld_object_match_name(const Obj_Entry *, const char *);
465 int _rtld_verify_object_versions(Obj_Entry *);
466
467 static __inline const Ver_Entry *
_rtld_fetch_ventry(const Obj_Entry * obj,unsigned long symnum)468 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
469 {
470 Elf_Half vernum;
471
472 if (obj->vertab) {
473 vernum = VER_NDX(obj->versyms[symnum].vs_vers);
474 if (vernum >= obj->vertabnum) {
475 _rtld_error("%s: symbol %s has wrong verneed value %d",
476 obj->path, &obj->strtab[symnum], vernum);
477 } else if (obj->vertab[vernum].hash) {
478 return &obj->vertab[vernum];
479 }
480 }
481 return NULL;
482 }
483
484 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
485 /* tls.c */
486 void *_rtld_tls_get_addr(void *, size_t, size_t);
487 void _rtld_tls_initial_allocation(void);
488 int _rtld_tls_offset_allocate(Obj_Entry *);
489 void _rtld_tls_offset_free(Obj_Entry *);
490
491 extern size_t _rtld_tls_dtv_generation;
492 extern size_t _rtld_tls_max_index;
493
494 __dso_public extern void *__tls_get_addr(void *);
495 #ifdef __i386__
496 __dso_public extern void *___tls_get_addr(void *)
497 __attribute__((__regparm__(1)));
498 #endif
499 #endif
500
501 /* map_object.c */
502 struct stat;
503 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
504 void _rtld_obj_free(Obj_Entry *);
505 Obj_Entry *_rtld_obj_new(void);
506
507 #ifdef RTLD_LOADER
508 /* function descriptors */
509 #ifdef __HAVE_FUNCTION_DESCRIPTORS
510 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
511 const Elf_Sym *, Elf_Addr);
512 const void *_rtld_function_descriptor_function(const void *);
513
514 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr);
515 #else
516 static inline Elf_Addr
_rtld_call_function_addr(const Obj_Entry * obj,Elf_Addr addr)517 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr)
518 {
519 return ((Elf_Addr(*)(void))addr)();
520 }
521 #endif /* __HAVE_FUNCTION_DESCRIPTORS */
522 #endif /* RTLD_LOADER */
523
524 #endif /* _RTLD_SOURCE */
525
526 #endif /* RTLD_H */
527