1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2
3 #ifndef _GNU_SOURCE
4 #define _GNU_SOURCE
5 #endif
6
7 #ifdef HAVE_LIBELF
8 #include <libelf.h>
9 #include <gelf.h>
10 #endif
11
12 #include <fcntl.h>
13 #include <linux/kernel.h>
14
15 #include "libbpf_internal.h"
16 #include "str_error.h"
17
18
19
20 #define STRERR_BUFSIZE 128
21
22 /* A SHT_GNU_versym section holds 16-bit words. This bit is set if
23 * the symbol is hidden and can only be seen when referenced using an
24 * explicit version number. This is a GNU extension.
25 */
26 #define VERSYM_HIDDEN 0x8000
27
28 /* This is the mask for the rest of the data in a word read from a
29 * SHT_GNU_versym section.
30 */
31 #define VERSYM_VERSION 0x7fff
32
33
34 #ifdef HAVE_LIBELF
elf_open(const char * binary_path,struct elf_fd * elf_fd)35 int elf_open(const char *binary_path, struct elf_fd *elf_fd)
36 {
37 char errmsg[STRERR_BUFSIZE];
38 int fd, ret;
39 Elf *elf;
40
41 if (elf_version(EV_CURRENT) == EV_NONE) {
42 pr_warn("elf: failed to init libelf for %s\n", binary_path);
43 return -LIBBPF_ERRNO__LIBELF;
44 }
45 fd = open(binary_path, O_RDONLY | O_CLOEXEC);
46 if (fd < 0) {
47 ret = -errno;
48 pr_warn("elf: failed to open %s: %s\n", binary_path,
49 libbpf_strerror_r(ret, errmsg, sizeof(errmsg)));
50 return ret;
51 }
52 elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
53 if (!elf) {
54 pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
55 close(fd);
56 return -LIBBPF_ERRNO__FORMAT;
57 }
58 elf_fd->fd = fd;
59 elf_fd->elf = elf;
60 return 0;
61 }
62 #elif HAVE_ELFIO
elf_open(const char * binary_path,struct elf_fd * elf_fd)63 int elf_open(const char *binary_path, struct elf_fd *elf_fd)
64 {
65 pelfio_t pelfio = elfio_new();
66 bool ret = false;
67 ret = elfio_load(pelfio, binary_path);
68 if (!ret) {
69 pr_warn("elf: could not read elf from %s: %s\n", binary_path, elf_errmsg(-1));
70 return -LIBBPF_ERRNO__FORMAT;
71 }
72 elf_fd->elf = pelfio;
73 elf_fd->fd = -1;
74 return 0;
75 }
76 #endif
77
78
elf_close(struct elf_fd * elf_fd)79 void elf_close(struct elf_fd *elf_fd)
80 {
81 if (!elf_fd)
82 return;
83 #ifdef HAVE_LIBELF
84 elf_end(elf_fd->elf);
85 close(elf_fd->fd);
86 #elif HAVE_ELFIO
87 elfio_delete(elf_fd->elf);
88 #endif
89 }
90
91 /* Return next ELF section of sh_type after scn, or first of that type if scn is NULL. */
92 #ifdef HAVE_LIBELF
elf_find_next_scn_by_type(Elf * elf,int sh_type,Elf_Scn * scn)93 static Elf_Scn *elf_find_next_scn_by_type(Elf *elf, int sh_type, Elf_Scn *scn)
94 {
95 while ((scn = elf_nextscn(elf, scn)) != NULL) {
96 GElf_Shdr sh;
97
98 if (!gelf_getshdr(scn, &sh))
99 continue;
100 if (sh.sh_type == sh_type)
101 return scn;
102 }
103 return NULL;
104 }
105 #elif HAVE_ELFIO
elf_find_next_scn_by_type(pelfio_t pelfio,int sh_type,psection_t pscn)106 static psection_t elf_find_next_scn_by_type(pelfio_t pelfio, int sh_type, psection_t pscn)
107 {
108 int secno = elfio_get_sections_num(pelfio);
109 int j = 0;
110 if (pscn != NULL) {
111 for (int i = 0; i < secno; i++) {
112 psection_t psection = elfio_get_section_by_index(pelfio, i);
113 if (psection == pscn) {
114 j = i;
115 }
116 }
117 }
118 for (; j < secno; j++) {
119 psection_t psection = elfio_get_section_by_index(pelfio, j);
120 Elf_Word sec_type = elfio_section_get_type(psection);
121 if (sec_type == sh_type) {
122 return psection;
123 }
124 }
125 return NULL;
126 }
127 #endif
128
129 struct elf_sym {
130 const char *name;
131 GElf_Sym sym;
132 GElf_Shdr sh;
133 int ver;
134 bool hidden;
135 };
136
137 struct elf_sym_iter {
138 #ifdef HAVE_LIBELF
139 Elf *elf;
140 #elif HAVE_ELFIO
141 pelfio_t elf;
142 psection_t symsSec;
143 #endif
144 Elf_Data *syms;
145 Elf_Data *versyms;
146 Elf_Data *verdefs;
147 size_t nr_syms;
148 size_t strtabidx;
149 size_t verdef_strtabidx;
150 size_t next_sym_idx;
151 struct elf_sym sym;
152 int st_type;
153 };
154
155 #ifdef HAVE_LIBELF
elf_sym_iter_new(struct elf_sym_iter * iter,Elf * elf,const char * binary_path,int sh_type,int st_type)156 static int elf_sym_iter_new(struct elf_sym_iter *iter,
157 Elf *elf, const char *binary_path,
158 int sh_type, int st_type)
159 {
160 Elf_Scn *scn = NULL;
161 GElf_Ehdr ehdr;
162 GElf_Shdr sh;
163
164 memset(iter, 0, sizeof(*iter));
165
166 if (!gelf_getehdr(elf, &ehdr)) {
167 pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
168 return -EINVAL;
169 }
170
171 scn = elf_find_next_scn_by_type(elf, sh_type, NULL);
172 if (!scn) {
173 pr_debug("elf: failed to find symbol table ELF sections in '%s'\n",
174 binary_path);
175 return -ENOENT;
176 }
177
178 if (!gelf_getshdr(scn, &sh))
179 return -EINVAL;
180
181 iter->strtabidx = sh.sh_link;
182 iter->syms = elf_getdata(scn, 0);
183 if (!iter->syms) {
184 pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
185 binary_path, elf_errmsg(-1));
186 return -EINVAL;
187 }
188 iter->nr_syms = iter->syms->d_size / sh.sh_entsize;
189 iter->elf = elf;
190 iter->st_type = st_type;
191
192 /* Version symbol table is meaningful to dynsym only */
193 if (sh_type != SHT_DYNSYM)
194 return 0;
195
196 scn = elf_find_next_scn_by_type(elf, SHT_GNU_versym, NULL);
197 if (!scn)
198 return 0;
199 iter->versyms = elf_getdata(scn, 0);
200
201 scn = elf_find_next_scn_by_type(elf, SHT_GNU_verdef, NULL);
202 if (!scn)
203 return 0;
204
205 iter->verdefs = elf_getdata(scn, 0);
206 if (!iter->verdefs || !gelf_getshdr(scn, &sh)) {
207 pr_warn("elf: failed to get verdef ELF section in '%s'\n", binary_path);
208 return -EINVAL;
209 }
210 iter->verdef_strtabidx = sh.sh_link;
211
212 return 0;
213 }
214 #elif HAVE_ELFIO
elf_sym_iter_new(struct elf_sym_iter * iter,pelfio_t elf,const char * binary_path,int sh_type,int st_type)215 static int elf_sym_iter_new(struct elf_sym_iter *iter,pelfio_t elf, const char *binary_path, int sh_type, int st_type)
216 {
217 psection_t pSec = NULL;
218 memset(iter, 0, sizeof(*iter));
219 pSec = elf_find_next_scn_by_type(elf, sh_type, NULL);
220 iter->strtabidx = elfio_section_get_link(pSec);
221 iter->syms->d_buf = (void*)elfio_section_get_data(pSec);
222 iter->syms->d_size = elfio_section_get_size(pSec);
223 if (!iter->syms->d_buf) {
224 pr_warn("elf: failed to get symbols for symtab section in '%s': %s\n",
225 binary_path, elf_errmsg(-1));
226 return -EINVAL;
227 }
228 iter->nr_syms = iter->syms->d_size / elfio_section_get_entry_size(pSec);
229 iter->symsSec = pSec;
230 iter->elf = elf;
231 iter->st_type = st_type;
232 /* Version symbol table is meaningful to dynsym only */
233 if (sh_type != SHT_DYNSYM)
234 return 0;
235 pSec = elf_find_next_scn_by_type(elf, SHT_GNU_versym, NULL);
236 if (!pSec) {
237 return 0;
238 }
239 iter->versyms->d_buf = (void*)elfio_section_get_data(pSec);
240 iter->versyms->d_size = elfio_section_get_size(pSec);
241 pSec = elf_find_next_scn_by_type(elf, SHT_GNU_verdef, NULL);
242 if (!pSec) {
243 return 0;
244 }
245 iter->verdefs->d_buf = (void*)elfio_section_get_data(pSec);
246 iter->verdefs->d_size = elfio_section_get_size(pSec);
247 if (!iter->verdefs->d_buf) {
248 pr_warn("elf: failed to get verdef ELF section in '%s'\n", binary_path);
249 return -EINVAL;
250 }
251 iter->verdef_strtabidx = elfio_section_get_link(pSec);
252 return 0;
253 }
254 #endif
255
256 #ifdef HAVA_ELFIO
elf_sec_hdr_by_idx(const pelfio_t elf,size_t idx,GElf_Shdr * sheader)257 static GElf_Shdr *elf_sec_hdr_by_idx(const pelfio_t elf, size_t idx, GElf_Shdr *sheader)
258 {
259 psection_t psection = elfio_get_section_by_index(elf, idx);
260 sheader->sh_name = elfio_section_get_name_string_offset(psection);
261 sheader->sh_type = elfio_section_get_type(psection);
262 sheader->sh_flags = elfio_section_get_flags(psection);
263 sheader->sh_addr = elfio_section_get_address(psection);
264 sheader->sh_offset = elfio_section_get_offset(psection);
265 sheader->sh_size = elfio_section_get_size(psection);
266 sheader->sh_link = elfio_section_get_link(psection);
267 sheader->sh_info = elfio_section_get_info(psection);
268 sheader->sh_addralign = elfio_section_get_addr_align(psection);
269 sheader->sh_entsize = elfio_section_get_entry_size(psection);
270 return sheader;
271 }
272 #endif //HAVA_ELFIO
273
274
elf_sym_iter_next(struct elf_sym_iter * iter)275 static struct elf_sym *elf_sym_iter_next(struct elf_sym_iter *iter)
276 {
277 struct elf_sym *ret = &iter->sym;
278 GElf_Sym *sym = &ret->sym;
279 GElf_Versym versym;
280 #ifdef HAVA_LIBELF
281 Elf_Scn *sym_scn;
282 #elif HAVE_ELFIO
283 psection_t sym_scn;
284 #endif
285 const char *name = NULL;
286 size_t idx;
287 for (idx = iter->next_sym_idx; idx < iter->nr_syms; idx++) {
288 #ifdef HAVA_LIBELF
289 if (!gelf_getsym(iter->syms, idx, sym))
290 continue;
291 if (GELF_ST_TYPE(sym->st_info) != iter->st_type)
292 continue;
293 name = elf_strptr(iter->elf, iter->strtabidx, sym->st_name);
294 if (!name)
295 continue;
296 sym_scn = elf_getscn(iter->elf, sym->st_shndx);
297 if (!sym_scn)
298 continue;
299 if (!gelf_getshdr(sym_scn, &ret->sh))
300 continue;
301 #elif HAVA_ELFIO
302 if(memcpy(sym,iter->sysms->d_buf + idx,sizeof(GElf_Sym) == NULL) {
303 continue;
304 }
305 if(((sym->st_info) & 0xf) != iter->st_type) {
306 continue;
307 }
308 psection_t psection = elfio_get_section_by_index(iter->elf, iter->strtabidx);
309 if (!psection)
310 return -LIBBPF_ERRNO__FORMAT;
311 pstring_t strstring = elfio_string_section_accessor_new(psection);
312 name = elfio_string_get_string(strstring, sym->st_name);
313 if(!name) {
314 continue;
315 }
316 if(!elf_sec_hdr_by_idx(iter->elf, sym->st_shndx, &ret->sh)) {
317 continue;
318 }
319 #endif
320 iter->next_sym_idx = idx + 1;
321 ret->name = name;
322 ret->ver = 0;
323 ret->hidden = false;
324 if (iter->versyms) {
325 #ifdef HAVA_LIBELF
326 if (!gelf_getversym(iter->versyms, idx, &versym))
327 continue;
328 #elif HAVA_ELFIO
329 versym = (GElf_Versym)iter->versysm->d_buf[idx];
330 #endif
331 ret->ver = versym & VERSYM_VERSION;
332 ret->hidden = versym & VERSYM_HIDDEN;
333 }
334 return ret;
335 }
336 return NULL;
337 }
338
elf_get_vername(struct elf_sym_iter * iter,int ver)339 static const char *elf_get_vername(struct elf_sym_iter *iter, int ver)
340 {
341 GElf_Verdaux verdaux;
342 GElf_Verdef verdef;
343 int offset;
344 if (!iter->verdefs)
345 return NULL;
346 offset = 0;
347 #ifdef HAVE_LIBELF
348 while (gelf_getverdef(iter->verdefs, offset, &verdef)) {
349 if (verdef.vd_ndx != ver) {
350 if (!verdef.vd_next)
351 break;
352 offset += verdef.vd_next;
353 continue;
354 }
355 if (!gelf_getverdaux(iter->verdefs, offset + verdef.vd_aux, &verdaux))
356 break;
357 return elf_strptr(iter->elf, iter->verdef_strtabidx, verdaux.vda_name);
358 }
359 #elif HAVE_ELFIO
360 while (memcpy(&verdef, (void *)iter->verdefs->d_buf + offset, sizeof(GElf_Verdef)) != NULL) {
361 if (verdef.vd_ndx != ver) {
362 if (!verdef.vd_next)
363 break;
364 offset += verdef.vd_next;
365 continue;
366 }
367 if(memcpy(&verdaux, (void *)iter->verdefs->d_buf + offset + verdef.vd_aux, sizeof(GElf_Verdaux)) == NULL) {
368 break;
369 }
370 psection_t psection = elfio_get_section_by_index(iter->elf, iter->verdef_strtabidx);
371 if (!psection)
372 return NULL;
373 pstring_t strstring = elfio_string_section_accessor_new(psection);
374 return elfio_string_get_string(strstring, verdaux.vda_name);
375 }
376 #endif
377 return NULL;
378 }
379
symbol_match(struct elf_sym_iter * iter,int sh_type,struct elf_sym * sym,const char * name,size_t name_len,const char * lib_ver)380 static bool symbol_match(struct elf_sym_iter *iter, int sh_type, struct elf_sym *sym,
381 const char *name, size_t name_len, const char *lib_ver)
382 {
383 const char *ver_name;
384
385 /* Symbols are in forms of func, func@LIB_VER or func@@LIB_VER
386 * make sure the func part matches the user specified name
387 */
388 if (strncmp(sym->name, name, name_len) != 0)
389 return false;
390
391 /* ...but we don't want a search for "foo" to match 'foo2" also, so any
392 * additional characters in sname should be of the form "@@LIB".
393 */
394 if (sym->name[name_len] != '\0' && sym->name[name_len] != '@')
395 return false;
396
397 /* If user does not specify symbol version, then we got a match */
398 if (!lib_ver)
399 return true;
400
401 /* If user specifies symbol version, for dynamic symbols,
402 * get version name from ELF verdef section for comparison.
403 */
404 if (sh_type == SHT_DYNSYM) {
405 ver_name = elf_get_vername(iter, sym->ver);
406 if (!ver_name)
407 return false;
408 return strcmp(ver_name, lib_ver) == 0;
409 }
410
411 /* For normal symbols, it is already in form of func@LIB_VER */
412 return strcmp(sym->name, name) == 0;
413 }
414
415 /* Transform symbol's virtual address (absolute for binaries and relative
416 * for shared libs) into file offset, which is what kernel is expecting
417 * for uprobe/uretprobe attachment.
418 * See Documentation/trace/uprobetracer.rst for more details. This is done
419 * by looking up symbol's containing section's header and using iter's virtual
420 * address (sh_addr) and corresponding file offset (sh_offset) to transform
421 * sym.st_value (virtual address) into desired final file offset.
422 */
elf_sym_offset(struct elf_sym * sym)423 static unsigned long elf_sym_offset(struct elf_sym *sym)
424 {
425 return sym->sym.st_value - sym->sh.sh_addr + sym->sh.sh_offset;
426 }
427
428 /* Find offset of function name in the provided ELF object. "binary_path" is
429 * the path to the ELF binary represented by "elf", and only used for error
430 * reporting matters. "name" matches symbol name or name@@LIB for library
431 * functions.
432 */
433 #ifdef HAVE_LIBELF
elf_find_func_offset(Elf * elf,const char * binary_path,const char * name)434 long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name)
435 #elif HAVE_ELFIO
436 long elf_find_func_offset(pelfio_t elf, const char *binary_path, const char *name)
437 #endif
438 {
439 int i, sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
440 const char *at_symbol, *lib_ver;
441 bool is_shared_lib;
442 long ret = -ENOENT;
443 size_t name_len;
444 #ifdef HAVE_LIBELF
445 GElf_Ehdr ehdr;
446
447 if (!gelf_getehdr(elf, &ehdr)) {
448 pr_warn("elf: failed to get ehdr from %s: %s\n", binary_path, elf_errmsg(-1));
449 ret = -LIBBPF_ERRNO__FORMAT;
450 goto out;
451 }
452
453 /* for shared lib case, we do not need to calculate relative offset */
454 is_shared_lib = ehdr.e_type == ET_DYN;
455 #elif HAVA_ELFIO
456 is_shared_lib = (ET_DYN == elfio_get_type(pelfio));
457 #endif
458 /* Does name specify "@@LIB_VER" or "@LIB_VER" ? */
459 at_symbol = strchr(name, '@');
460 if (at_symbol) {
461 name_len = at_symbol - name;
462 /* skip second @ if it's @@LIB_VER case */
463 if (at_symbol[1] == '@')
464 at_symbol++;
465 lib_ver = at_symbol + 1;
466 } else {
467 name_len = strlen(name);
468 lib_ver = NULL;
469 }
470
471 /* Search SHT_DYNSYM, SHT_SYMTAB for symbol. This search order is used because if
472 * a binary is stripped, it may only have SHT_DYNSYM, and a fully-statically
473 * linked binary may not have SHT_DYMSYM, so absence of a section should not be
474 * reported as a warning/error.
475 */
476 for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
477 struct elf_sym_iter iter;
478 struct elf_sym *sym;
479 int last_bind = -1;
480 int cur_bind;
481
482 ret = elf_sym_iter_new(&iter, elf, binary_path, sh_types[i], STT_FUNC);
483 if (ret == -ENOENT)
484 continue;
485 if (ret)
486 goto out;
487
488 while ((sym = elf_sym_iter_next(&iter))) {
489 if (!symbol_match(&iter, sh_types[i], sym, name, name_len, lib_ver))
490 continue;
491
492 cur_bind = GELF_ST_BIND(sym->sym.st_info);
493
494 if (ret > 0) {
495 /* handle multiple matches */
496 if (elf_sym_offset(sym) == ret) {
497 /* same offset, no problem */
498 continue;
499 } else if (last_bind != STB_WEAK && cur_bind != STB_WEAK) {
500 /* Only accept one non-weak bind. */
501 pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
502 sym->name, name, binary_path);
503 ret = -LIBBPF_ERRNO__FORMAT;
504 goto out;
505 } else if (cur_bind == STB_WEAK) {
506 /* already have a non-weak bind, and
507 * this is a weak bind, so ignore.
508 */
509 continue;
510 }
511 }
512
513 ret = elf_sym_offset(sym);
514 last_bind = cur_bind;
515 }
516 if (ret > 0)
517 break;
518 }
519
520 if (ret > 0) {
521 pr_debug("elf: symbol address match for '%s' in '%s': 0x%lx\n", name, binary_path,
522 ret);
523 } else {
524 if (ret == 0) {
525 pr_warn("elf: '%s' is 0 in symtab for '%s': %s\n", name, binary_path,
526 is_shared_lib ? "should not be 0 in a shared library" :
527 "try using shared library path instead");
528 ret = -ENOENT;
529 } else {
530 pr_warn("elf: failed to find symbol '%s' in '%s'\n", name, binary_path);
531 }
532 }
533 out:
534 return ret;
535 }
536
537 /* Find offset of function name in ELF object specified by path. "name" matches
538 * symbol name or name@@LIB for library functions.
539 */
elf_find_func_offset_from_file(const char * binary_path,const char * name)540 long elf_find_func_offset_from_file(const char *binary_path, const char *name)
541 {
542 struct elf_fd elf_fd;
543 long ret = -ENOENT;
544
545 ret = elf_open(binary_path, &elf_fd);
546 if (ret)
547 return ret;
548 ret = elf_find_func_offset(elf_fd.elf, binary_path, name);
549 elf_close(&elf_fd);
550 return ret;
551 }
552
553 struct symbol {
554 const char *name;
555 int bind;
556 int idx;
557 };
558
symbol_cmp(const void * a,const void * b)559 static int symbol_cmp(const void *a, const void *b)
560 {
561 const struct symbol *sym_a = a;
562 const struct symbol *sym_b = b;
563
564 return strcmp(sym_a->name, sym_b->name);
565 }
566
567 /*
568 * Return offsets in @poffsets for symbols specified in @syms array argument.
569 * On success returns 0 and offsets are returned in allocated array with @cnt
570 * size, that needs to be released by the caller.
571 */
elf_resolve_syms_offsets(const char * binary_path,int cnt,const char ** syms,unsigned long ** poffsets)572 int elf_resolve_syms_offsets(const char *binary_path, int cnt,
573 const char **syms, unsigned long **poffsets)
574 {
575 int sh_types[2] = { SHT_DYNSYM, SHT_SYMTAB };
576 int err = 0, i, cnt_done = 0;
577 unsigned long *offsets;
578 struct symbol *symbols;
579 struct elf_fd elf_fd;
580
581 err = elf_open(binary_path, &elf_fd);
582 if (err)
583 return err;
584
585 offsets = calloc(cnt, sizeof(*offsets));
586 symbols = calloc(cnt, sizeof(*symbols));
587
588 if (!offsets || !symbols) {
589 err = -ENOMEM;
590 goto out;
591 }
592
593 for (i = 0; i < cnt; i++) {
594 symbols[i].name = syms[i];
595 symbols[i].idx = i;
596 }
597
598 qsort(symbols, cnt, sizeof(*symbols), symbol_cmp);
599
600 for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
601 struct elf_sym_iter iter;
602 struct elf_sym *sym;
603
604 err = elf_sym_iter_new(&iter, elf_fd.elf, binary_path, sh_types[i], STT_FUNC);
605 if (err == -ENOENT)
606 continue;
607 if (err)
608 goto out;
609
610 while ((sym = elf_sym_iter_next(&iter))) {
611 unsigned long sym_offset = elf_sym_offset(sym);
612 int bind = GELF_ST_BIND(sym->sym.st_info);
613 struct symbol *found, tmp = {
614 .name = sym->name,
615 };
616 unsigned long *offset;
617
618 found = bsearch(&tmp, symbols, cnt, sizeof(*symbols), symbol_cmp);
619 if (!found)
620 continue;
621
622 offset = &offsets[found->idx];
623 if (*offset > 0) {
624 /* same offset, no problem */
625 if (*offset == sym_offset)
626 continue;
627 /* handle multiple matches */
628 if (found->bind != STB_WEAK && bind != STB_WEAK) {
629 /* Only accept one non-weak bind. */
630 pr_warn("elf: ambiguous match found '%s@%lu' in '%s' previous offset %lu\n",
631 sym->name, sym_offset, binary_path, *offset);
632 err = -ESRCH;
633 goto out;
634 } else if (bind == STB_WEAK) {
635 /* already have a non-weak bind, and
636 * this is a weak bind, so ignore.
637 */
638 continue;
639 }
640 } else {
641 cnt_done++;
642 }
643 *offset = sym_offset;
644 found->bind = bind;
645 }
646 }
647
648 if (cnt != cnt_done) {
649 err = -ENOENT;
650 goto out;
651 }
652
653 *poffsets = offsets;
654
655 out:
656 free(symbols);
657 if (err)
658 free(offsets);
659 elf_close(&elf_fd);
660 return err;
661 }
662
663 /*
664 * Return offsets in @poffsets for symbols specified by @pattern argument.
665 * On success returns 0 and offsets are returned in allocated @poffsets
666 * array with the @pctn size, that needs to be released by the caller.
667 */
elf_resolve_pattern_offsets(const char * binary_path,const char * pattern,unsigned long ** poffsets,size_t * pcnt)668 int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
669 unsigned long **poffsets, size_t *pcnt)
670 {
671 int sh_types[2] = { SHT_SYMTAB, SHT_DYNSYM };
672 unsigned long *offsets = NULL;
673 size_t cap = 0, cnt = 0;
674 struct elf_fd elf_fd;
675 int err = 0, i;
676
677 err = elf_open(binary_path, &elf_fd);
678 if (err)
679 return err;
680
681 for (i = 0; i < ARRAY_SIZE(sh_types); i++) {
682 struct elf_sym_iter iter;
683 struct elf_sym *sym;
684
685 err = elf_sym_iter_new(&iter, elf_fd.elf, binary_path, sh_types[i], STT_FUNC);
686 if (err == -ENOENT)
687 continue;
688 if (err)
689 goto out;
690
691 while ((sym = elf_sym_iter_next(&iter))) {
692 if (!glob_match(sym->name, pattern))
693 continue;
694
695 err = libbpf_ensure_mem((void **) &offsets, &cap, sizeof(*offsets),
696 cnt + 1);
697 if (err)
698 goto out;
699
700 offsets[cnt++] = elf_sym_offset(sym);
701 }
702
703 /* If we found anything in the first symbol section,
704 * do not search others to avoid duplicates.
705 */
706 if (cnt)
707 break;
708 }
709
710 if (cnt) {
711 *poffsets = offsets;
712 *pcnt = cnt;
713 } else {
714 err = -ENOENT;
715 }
716
717 out:
718 if (err)
719 free(offsets);
720 elf_close(&elf_fd);
721 return err;
722 }
723