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1 | /* |
2 | * Copyright (C) 2015 Antoine Busque <abusque@efficios.com> | |
3 | * Copyright (C) 2017 Francis Deslauriers <francis.deslauriers@efficios.com> | |
4 | * Copyright (C) 2017 Erica Bugden <erica.bugden@efficios.com> | |
5 | * | |
6 | * This library is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; either | |
9 | * version 2.1 of the License, or (at your option) any later version. | |
10 | * | |
11 | * This library is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with this library; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | */ | |
20 | ||
21 | #include <common/compat/endian.h> | |
22 | #include <common/error.h> | |
23 | #include <common/lttng-elf.h> | |
24 | #include <common/macros.h> | |
25 | #include <common/readwrite.h> | |
26 | #include <fcntl.h> | |
27 | #include <stdbool.h> | |
28 | #include <stdint.h> | |
29 | #include <stdlib.h> | |
30 | #include <string.h> | |
31 | #include <sys/stat.h> | |
32 | #include <sys/types.h> | |
33 | #include <unistd.h> | |
34 | ||
35 | #include <elf.h> | |
36 | ||
37 | #define BUF_LEN 4096 | |
38 | #define TEXT_SECTION_NAME ".text" | |
39 | #define SYMBOL_TAB_SECTION_NAME ".symtab" | |
40 | #define STRING_TAB_SECTION_NAME ".strtab" | |
41 | #define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt" | |
42 | #define NOTE_STAPSDT_NAME "stapsdt" | |
43 | #define NOTE_STAPSDT_TYPE 3 | |
44 | ||
45 | #if BYTE_ORDER == LITTLE_ENDIAN | |
46 | #define NATIVE_ELF_ENDIANNESS ELFDATA2LSB | |
47 | #else | |
48 | #define NATIVE_ELF_ENDIANNESS ELFDATA2MSB | |
49 | #endif | |
50 | ||
51 | #define bswap(x) \ | |
52 | do { \ | |
53 | switch (sizeof(x)) { \ | |
54 | case 8: \ | |
55 | x = be64toh(x); \ | |
56 | break; \ | |
57 | case 4: \ | |
58 | x = be32toh(x); \ | |
59 | break; \ | |
60 | case 2: \ | |
61 | x = be16toh(x); \ | |
62 | break; \ | |
63 | case 1: \ | |
64 | break; \ | |
65 | default: \ | |
66 | abort(); \ | |
67 | } \ | |
68 | } while (0) | |
69 | ||
70 | #define bswap_shdr(shdr) \ | |
71 | do { \ | |
72 | bswap((shdr).sh_name); \ | |
73 | bswap((shdr).sh_type); \ | |
74 | bswap((shdr).sh_flags); \ | |
75 | bswap((shdr).sh_addr); \ | |
76 | bswap((shdr).sh_offset); \ | |
77 | bswap((shdr).sh_size); \ | |
78 | bswap((shdr).sh_link); \ | |
79 | bswap((shdr).sh_info); \ | |
80 | bswap((shdr).sh_addralign); \ | |
81 | bswap((shdr).sh_entsize); \ | |
82 | } while (0) | |
83 | ||
84 | #define bswap_ehdr(ehdr) \ | |
85 | do { \ | |
86 | bswap((ehdr).e_type); \ | |
87 | bswap((ehdr).e_machine); \ | |
88 | bswap((ehdr).e_version); \ | |
89 | bswap((ehdr).e_entry); \ | |
90 | bswap((ehdr).e_phoff); \ | |
91 | bswap((ehdr).e_shoff); \ | |
92 | bswap((ehdr).e_flags); \ | |
93 | bswap((ehdr).e_ehsize); \ | |
94 | bswap((ehdr).e_phentsize); \ | |
95 | bswap((ehdr).e_phnum); \ | |
96 | bswap((ehdr).e_shentsize); \ | |
97 | bswap((ehdr).e_shnum); \ | |
98 | bswap((ehdr).e_shstrndx); \ | |
99 | } while (0) | |
100 | ||
101 | #define copy_shdr(src_shdr, dst_shdr) \ | |
102 | do { \ | |
103 | (dst_shdr).sh_name = (src_shdr).sh_name; \ | |
104 | (dst_shdr).sh_type = (src_shdr).sh_type; \ | |
105 | (dst_shdr).sh_flags = (src_shdr).sh_flags; \ | |
106 | (dst_shdr).sh_addr = (src_shdr).sh_addr; \ | |
107 | (dst_shdr).sh_offset = (src_shdr).sh_offset; \ | |
108 | (dst_shdr).sh_size = (src_shdr).sh_size; \ | |
109 | (dst_shdr).sh_link = (src_shdr).sh_link; \ | |
110 | (dst_shdr).sh_info = (src_shdr).sh_info; \ | |
111 | (dst_shdr).sh_addralign = (src_shdr).sh_addralign; \ | |
112 | (dst_shdr).sh_entsize = (src_shdr).sh_entsize; \ | |
113 | } while (0) | |
114 | ||
115 | #define copy_ehdr(src_ehdr, dst_ehdr) \ | |
116 | do { \ | |
117 | (dst_ehdr).e_type = (src_ehdr).e_type; \ | |
118 | (dst_ehdr).e_machine = (src_ehdr).e_machine; \ | |
119 | (dst_ehdr).e_version = (src_ehdr).e_version; \ | |
120 | (dst_ehdr).e_entry = (src_ehdr).e_entry; \ | |
121 | (dst_ehdr).e_phoff = (src_ehdr).e_phoff; \ | |
122 | (dst_ehdr).e_shoff = (src_ehdr).e_shoff; \ | |
123 | (dst_ehdr).e_flags = (src_ehdr).e_flags; \ | |
124 | (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize; \ | |
125 | (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize; \ | |
126 | (dst_ehdr).e_phnum = (src_ehdr).e_phnum; \ | |
127 | (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize; \ | |
128 | (dst_ehdr).e_shnum = (src_ehdr).e_shnum; \ | |
129 | (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx; \ | |
130 | } while (0) | |
131 | ||
132 | #define copy_sym(src_sym, dst_sym) \ | |
133 | do { \ | |
134 | dst_sym.st_name = src_sym.st_name; \ | |
135 | dst_sym.st_info = src_sym.st_info; \ | |
136 | dst_sym.st_other = src_sym.st_other; \ | |
137 | dst_sym.st_shndx = src_sym.st_shndx; \ | |
138 | dst_sym.st_value = src_sym.st_value; \ | |
139 | dst_sym.st_size = src_sym.st_size; \ | |
140 | } while (0) | |
141 | ||
142 | /* Both 32bit and 64bit use the same 1 byte field for type. (See elf.h) */ | |
143 | #define ELF_ST_TYPE(val) ELF32_ST_TYPE(val) | |
144 | ||
145 | struct lttng_elf_ehdr { | |
146 | uint16_t e_type; | |
147 | uint16_t e_machine; | |
148 | uint32_t e_version; | |
149 | uint64_t e_entry; | |
150 | uint64_t e_phoff; | |
151 | uint64_t e_shoff; | |
152 | uint32_t e_flags; | |
153 | uint16_t e_ehsize; | |
154 | uint16_t e_phentsize; | |
155 | uint16_t e_phnum; | |
156 | uint16_t e_shentsize; | |
157 | uint16_t e_shnum; | |
158 | uint16_t e_shstrndx; | |
159 | }; | |
160 | ||
161 | struct lttng_elf_shdr { | |
162 | uint32_t sh_name; | |
163 | uint32_t sh_type; | |
164 | uint64_t sh_flags; | |
165 | uint64_t sh_addr; | |
166 | uint64_t sh_offset; | |
167 | uint64_t sh_size; | |
168 | uint32_t sh_link; | |
169 | uint32_t sh_info; | |
170 | uint64_t sh_addralign; | |
171 | uint64_t sh_entsize; | |
172 | }; | |
173 | ||
174 | /* | |
175 | * This struct can hold both 32bit and 64bit symbol description. It's used with | |
176 | * the copy_sym() macro. Using this abstraction, we can use the same code for | |
177 | * both bitness. | |
178 | */ | |
179 | struct lttng_elf_sym { | |
180 | uint32_t st_name; | |
181 | uint8_t st_info; | |
182 | uint8_t st_other; | |
183 | uint16_t st_shndx; | |
184 | uint64_t st_value; | |
185 | uint64_t st_size; | |
186 | }; | |
187 | ||
188 | struct lttng_elf { | |
189 | int fd; | |
190 | uint8_t bitness; | |
191 | uint8_t endianness; | |
192 | /* Offset in bytes to start of section names string table. */ | |
193 | off_t section_names_offset; | |
194 | /* Size in bytes of section names string table. */ | |
195 | size_t section_names_size; | |
196 | struct lttng_elf_ehdr *ehdr; | |
197 | }; | |
198 | ||
199 | static inline | |
200 | int is_elf_32_bit(struct lttng_elf *elf) | |
201 | { | |
202 | return elf->bitness == ELFCLASS32; | |
203 | } | |
204 | ||
205 | static inline | |
206 | int is_elf_native_endian(struct lttng_elf *elf) | |
207 | { | |
208 | return elf->endianness == NATIVE_ELF_ENDIANNESS; | |
209 | } | |
210 | ||
211 | static | |
212 | int populate_section_header(struct lttng_elf * elf, struct lttng_elf_shdr *shdr, | |
213 | uint32_t index) | |
214 | { | |
215 | int ret = 0; | |
216 | off_t offset; | |
217 | ||
218 | /* Compute the offset of the section in the file */ | |
219 | offset = (off_t) elf->ehdr->e_shoff | |
220 | + (off_t) index * elf->ehdr->e_shentsize; | |
221 | ||
222 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { | |
223 | PERROR("Error seeking to the beginning of ELF section header"); | |
224 | ret = -1; | |
225 | goto error; | |
226 | } | |
227 | ||
228 | if (is_elf_32_bit(elf)) { | |
229 | Elf32_Shdr elf_shdr; | |
230 | ||
231 | if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) { | |
232 | PERROR("Error reading ELF section header"); | |
233 | ret = -1; | |
234 | goto error; | |
235 | } | |
236 | if (!is_elf_native_endian(elf)) { | |
237 | bswap_shdr(elf_shdr); | |
238 | } | |
239 | copy_shdr(elf_shdr, *shdr); | |
240 | } else { | |
241 | Elf64_Shdr elf_shdr; | |
242 | ||
243 | if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) { | |
244 | PERROR("Error reading ELF section header"); | |
245 | ret = -1; | |
246 | goto error; | |
247 | } | |
248 | if (!is_elf_native_endian(elf)) { | |
249 | bswap_shdr(elf_shdr); | |
250 | } | |
251 | copy_shdr(elf_shdr, *shdr); | |
252 | } | |
253 | ||
254 | error: | |
255 | return ret; | |
256 | } | |
257 | ||
258 | static | |
259 | int populate_elf_header(struct lttng_elf *elf) | |
260 | { | |
261 | int ret = 0; | |
262 | ||
263 | /* | |
264 | * Move the read pointer back to the beginning to read the full header | |
265 | * and copy it in our structure. | |
266 | */ | |
267 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
268 | PERROR("Error seeking to the beginning of the file"); | |
269 | ret = -1; | |
270 | goto error; | |
271 | } | |
272 | ||
273 | /* | |
274 | * Use macros to set fields in the ELF header struct for both 32bit and | |
275 | * 64bit. | |
276 | */ | |
277 | if (is_elf_32_bit(elf)) { | |
278 | Elf32_Ehdr elf_ehdr; | |
279 | ||
280 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
281 | ret = -1; | |
282 | goto error; | |
283 | } | |
284 | if (!is_elf_native_endian(elf)) { | |
285 | bswap_ehdr(elf_ehdr); | |
286 | } | |
287 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
288 | } else { | |
289 | Elf64_Ehdr elf_ehdr; | |
290 | ||
291 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
292 | ret = -1; | |
293 | goto error; | |
294 | } | |
295 | if (!is_elf_native_endian(elf)) { | |
296 | bswap_ehdr(elf_ehdr); | |
297 | } | |
298 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
299 | } | |
300 | error: | |
301 | return ret; | |
302 | } | |
303 | ||
304 | /* | |
305 | * Retrieve the nth (where n is the `index` argument) shdr (section | |
306 | * header) from the given elf instance. | |
307 | * | |
308 | * A pointer to the shdr is returned on success, NULL on failure. | |
309 | */ | |
310 | static | |
311 | struct lttng_elf_shdr *lttng_elf_get_section_hdr(struct lttng_elf *elf, | |
312 | uint16_t index) | |
313 | { | |
314 | struct lttng_elf_shdr *section_header = NULL; | |
315 | int ret = 0; | |
316 | ||
317 | if (!elf) { | |
318 | goto error; | |
319 | } | |
320 | ||
321 | if (index >= elf->ehdr->e_shnum) { | |
322 | goto error; | |
323 | } | |
324 | ||
325 | section_header = zmalloc(sizeof(struct lttng_elf_shdr)); | |
326 | if (!section_header) { | |
327 | goto error; | |
328 | } | |
329 | ||
330 | ret = populate_section_header(elf, section_header, index); | |
331 | if (ret) { | |
332 | ret = LTTNG_ERR_ELF_PARSING; | |
333 | DBG("Error populating section header."); | |
334 | goto error; | |
335 | } | |
336 | return section_header; | |
337 | ||
338 | error: | |
339 | free(section_header); | |
340 | return NULL; | |
341 | } | |
342 | ||
343 | /* | |
344 | * Lookup a section's name from a given offset (usually from an shdr's | |
345 | * sh_name value) in bytes relative to the beginning of the section | |
346 | * names string table. | |
347 | * | |
348 | * If no name is found, NULL is returned. | |
349 | */ | |
350 | static | |
351 | char *lttng_elf_get_section_name(struct lttng_elf *elf, off_t offset) | |
352 | { | |
353 | char *name = NULL; | |
354 | size_t name_length = 0, to_read; /* name_length does not include \0 */ | |
355 | ||
356 | if (!elf) { | |
357 | goto error; | |
358 | } | |
359 | ||
360 | if (offset >= elf->section_names_size) { | |
361 | goto error; | |
362 | } | |
363 | ||
364 | if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) { | |
365 | PERROR("Error seeking to the beginning of ELF string table section"); | |
366 | goto error; | |
367 | } | |
368 | ||
369 | to_read = elf->section_names_size - offset; | |
370 | ||
371 | /* Find first \0 after or at current location, remember name_length. */ | |
372 | for (;;) { | |
373 | char buf[BUF_LEN]; | |
374 | ssize_t read_len; | |
375 | size_t i; | |
376 | ||
377 | if (!to_read) { | |
378 | goto error; | |
379 | } | |
380 | read_len = lttng_read(elf->fd, buf, min_t(size_t, BUF_LEN, to_read)); | |
381 | if (read_len <= 0) { | |
382 | PERROR("Error reading ELF string table section"); | |
383 | goto error; | |
384 | } | |
385 | for (i = 0; i < read_len; i++) { | |
386 | if (buf[i] == '\0') { | |
387 | name_length += i; | |
388 | goto end; | |
389 | } | |
390 | } | |
391 | name_length += read_len; | |
392 | to_read -= read_len; | |
393 | } | |
394 | end: | |
395 | /* | |
396 | * We found the length of the section name, now seek back to the | |
397 | * beginning of the name and copy it in the newly allocated buffer. | |
398 | */ | |
399 | name = zmalloc(sizeof(char) * (name_length + 1)); /* + 1 for \0 */ | |
400 | if (!name) { | |
401 | PERROR("Error allocating ELF section name buffer"); | |
402 | goto error; | |
403 | } | |
404 | if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) { | |
405 | PERROR("Error seeking to the offset of the ELF section name"); | |
406 | goto error; | |
407 | } | |
408 | if (lttng_read(elf->fd, name, name_length + 1) < name_length + 1) { | |
409 | PERROR("Error reading the ELF section name"); | |
410 | goto error; | |
411 | } | |
412 | ||
413 | return name; | |
414 | ||
415 | error: | |
416 | free(name); | |
417 | return NULL; | |
418 | } | |
419 | ||
420 | static | |
421 | int lttng_elf_validate_and_populate(struct lttng_elf *elf) | |
422 | { | |
423 | uint8_t version; | |
424 | uint8_t e_ident[EI_NIDENT]; | |
425 | uint8_t *magic_number = NULL; | |
426 | int ret = 0; | |
427 | ||
428 | if (elf->fd == -1) { | |
429 | DBG("fd error"); | |
430 | ret = LTTNG_ERR_ELF_PARSING; | |
431 | goto end; | |
432 | } | |
433 | ||
434 | /* | |
435 | * First read the magic number, endianness and version to later populate | |
436 | * the ELF header with the correct endianness and bitness. | |
437 | * (see elf.h) | |
438 | */ | |
439 | ||
440 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
441 | PERROR("Error seeking the beginning of ELF file"); | |
442 | ret = LTTNG_ERR_ELF_PARSING; | |
443 | goto end; | |
444 | } | |
445 | ret = lttng_read(elf->fd, e_ident, EI_NIDENT); | |
446 | if (ret < EI_NIDENT) { | |
447 | DBG("Error reading the ELF identification fields"); | |
448 | if (ret == -1) { | |
449 | PERROR("Error reading the ELF identification fields"); | |
450 | } | |
451 | ret = LTTNG_ERR_ELF_PARSING; | |
452 | goto end; | |
453 | } | |
454 | ||
455 | /* | |
456 | * Copy fields used to check that the target file is in fact a valid ELF | |
457 | * file. | |
458 | */ | |
459 | elf->bitness = e_ident[EI_CLASS]; | |
460 | elf->endianness = e_ident[EI_DATA]; | |
461 | version = e_ident[EI_VERSION]; | |
462 | magic_number = &e_ident[EI_MAG0]; | |
463 | ||
464 | /* | |
465 | * Check the magic number. | |
466 | */ | |
467 | if (memcmp(magic_number, ELFMAG, SELFMAG) != 0) { | |
468 | DBG("Error check ELF magic number."); | |
469 | ret = LTTNG_ERR_ELF_PARSING; | |
470 | goto end; | |
471 | } | |
472 | ||
473 | /* | |
474 | * Check the bitness is either ELFCLASS32 or ELFCLASS64. | |
475 | */ | |
476 | if (elf->bitness <= ELFCLASSNONE || elf->bitness >= ELFCLASSNUM) { | |
477 | DBG("ELF class error."); | |
478 | ret = LTTNG_ERR_ELF_PARSING; | |
479 | goto end; | |
480 | } | |
481 | ||
482 | /* | |
483 | * Check the endianness is either ELFDATA2LSB or ELFDATA2MSB. | |
484 | */ | |
485 | if (elf->endianness <= ELFDATANONE || elf->endianness >= ELFDATANUM) { | |
486 | DBG("ELF endianness error."); | |
487 | ret = LTTNG_ERR_ELF_PARSING; | |
488 | goto end; | |
489 | } | |
490 | ||
491 | /* | |
492 | * Check the version is ELF_CURRENT. | |
493 | */ | |
494 | if (version <= EV_NONE || version >= EV_NUM) { | |
495 | DBG("Wrong ELF version."); | |
496 | ret = LTTNG_ERR_ELF_PARSING; | |
497 | goto end; | |
498 | } | |
499 | ||
500 | elf->ehdr = zmalloc(sizeof(struct lttng_elf_ehdr)); | |
501 | if (!elf->ehdr) { | |
502 | PERROR("Error allocation buffer for ELF header"); | |
503 | ret = LTTNG_ERR_NOMEM; | |
504 | goto end; | |
505 | } | |
506 | ||
507 | /* | |
508 | * Copy the content of the elf header. | |
509 | */ | |
510 | ret = populate_elf_header(elf); | |
511 | if (ret) { | |
512 | DBG("Error reading ELF header,"); | |
513 | goto free_elf_error; | |
514 | } | |
515 | ||
516 | goto end; | |
517 | ||
518 | free_elf_error: | |
519 | free(elf->ehdr); | |
520 | elf->ehdr = NULL; | |
521 | end: | |
522 | return ret; | |
523 | } | |
524 | ||
525 | /* | |
526 | * Create an instance of lttng_elf for the ELF file located at | |
527 | * `path`. | |
528 | * | |
529 | * Return a pointer to the instance on success, NULL on failure. | |
530 | */ | |
531 | static | |
532 | struct lttng_elf *lttng_elf_create(int fd) | |
533 | { | |
534 | struct lttng_elf_shdr *section_names_shdr; | |
535 | struct lttng_elf *elf = NULL; | |
536 | int ret; | |
537 | ||
538 | if (fd < 0) { | |
539 | goto error; | |
540 | } | |
541 | ||
542 | elf = zmalloc(sizeof(struct lttng_elf)); | |
543 | if (!elf) { | |
544 | PERROR("Error allocating struct lttng_elf"); | |
545 | goto error; | |
546 | } | |
547 | ||
548 | elf->fd = dup(fd); | |
549 | if (elf->fd < 0) { | |
550 | PERROR("Error duplicating file descriptor to binary"); | |
551 | goto error; | |
552 | } | |
553 | ||
554 | ret = lttng_elf_validate_and_populate(elf); | |
555 | if (ret) { | |
556 | goto error; | |
557 | } | |
558 | ||
559 | section_names_shdr = lttng_elf_get_section_hdr(elf, elf->ehdr->e_shstrndx); | |
560 | if (!section_names_shdr) { | |
561 | goto error; | |
562 | } | |
563 | ||
564 | elf->section_names_offset = section_names_shdr->sh_offset; | |
565 | elf->section_names_size = section_names_shdr->sh_size; | |
566 | ||
567 | free(section_names_shdr); | |
568 | return elf; | |
569 | ||
570 | error: | |
571 | if (elf) { | |
572 | if (elf->ehdr) { | |
573 | free(elf->ehdr); | |
574 | } | |
575 | if (elf->fd >= 0) { | |
576 | if (close(elf->fd)) { | |
577 | PERROR("Error closing file descriptor in error path"); | |
578 | abort(); | |
579 | } | |
580 | } | |
581 | free(elf); | |
582 | } | |
583 | return NULL; | |
584 | } | |
585 | ||
586 | /* | |
587 | * Destroy the given lttng_elf instance. | |
588 | */ | |
589 | static | |
590 | void lttng_elf_destroy(struct lttng_elf *elf) | |
591 | { | |
592 | if (!elf) { | |
593 | return; | |
594 | } | |
595 | ||
596 | free(elf->ehdr); | |
597 | if (close(elf->fd)) { | |
598 | PERROR("Error closing file description in error path"); | |
599 | abort(); | |
600 | } | |
601 | free(elf); | |
602 | } | |
603 | ||
604 | static | |
605 | int lttng_elf_get_section_hdr_by_name(struct lttng_elf *elf, | |
606 | const char *section_name, struct lttng_elf_shdr **section_hdr) | |
607 | { | |
608 | int i; | |
609 | char *curr_section_name; | |
610 | for (i = 0; i < elf->ehdr->e_shnum; ++i) { | |
611 | *section_hdr = lttng_elf_get_section_hdr(elf, i); | |
612 | curr_section_name = lttng_elf_get_section_name(elf, | |
613 | (*section_hdr)->sh_name); | |
614 | ||
615 | if (!curr_section_name) { | |
616 | continue; | |
617 | } | |
618 | if (strcmp(curr_section_name, section_name) == 0) { | |
619 | return 0; | |
620 | } | |
621 | } | |
622 | return LTTNG_ERR_ELF_PARSING; | |
623 | } | |
624 | ||
625 | static | |
626 | char *lttng_elf_get_section_data(struct lttng_elf *elf, | |
627 | struct lttng_elf_shdr *shdr) | |
628 | { | |
629 | int ret; | |
630 | off_t section_offset; | |
631 | char *data; | |
632 | ||
633 | if (!elf || !shdr) { | |
634 | goto error; | |
635 | } | |
636 | ||
637 | section_offset = shdr->sh_offset; | |
638 | if (lseek(elf->fd, section_offset, SEEK_SET) < 0) { | |
639 | PERROR("Error seeking to section offset"); | |
640 | goto error; | |
641 | } | |
642 | ||
643 | data = zmalloc(shdr->sh_size); | |
644 | if (!data) { | |
645 | PERROR("Error allocating buffer for ELF section data"); | |
646 | goto error; | |
647 | } | |
648 | ret = lttng_read(elf->fd, data, shdr->sh_size); | |
649 | if (ret == -1) { | |
650 | PERROR("Error reading ELF section data"); | |
651 | goto free_error; | |
652 | } | |
653 | ||
654 | return data; | |
655 | ||
656 | free_error: | |
657 | free(data); | |
658 | error: | |
659 | return NULL; | |
660 | } | |
661 | ||
662 | /* | |
663 | * Convert the virtual address in a binary's mapping to the offset of | |
664 | * the corresponding instruction in the binary file. | |
665 | * This function assumes the address is in the text section. | |
666 | * | |
667 | * Returns the offset on success or non-zero in case of failure. | |
668 | */ | |
669 | static | |
670 | int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle, | |
671 | size_t addr, uint64_t *offset) | |
672 | { | |
673 | int ret = 0; | |
674 | off_t text_section_offset; | |
675 | off_t text_section_addr_beg; | |
676 | off_t text_section_addr_end; | |
677 | off_t offset_in_section; | |
678 | struct lttng_elf_shdr *text_section_hdr = NULL; | |
679 | ||
680 | if (!elf_handle) { | |
681 | DBG("Invalid ELF handle."); | |
682 | ret = LTTNG_ERR_ELF_PARSING; | |
683 | goto error; | |
684 | } | |
685 | ||
686 | /* Get a pointer to the .text section header. */ | |
687 | ret = lttng_elf_get_section_hdr_by_name(elf_handle, | |
688 | TEXT_SECTION_NAME, &text_section_hdr); | |
689 | if (ret) { | |
690 | DBG("Text section not found in binary."); | |
691 | ret = LTTNG_ERR_ELF_PARSING; | |
692 | goto error; | |
693 | } | |
694 | ||
695 | text_section_offset = text_section_hdr->sh_offset; | |
696 | text_section_addr_beg = text_section_hdr->sh_addr; | |
697 | text_section_addr_end = text_section_addr_beg + text_section_hdr->sh_size; | |
698 | ||
699 | /* | |
700 | * Verify that the address is within the .text section boundaries. | |
701 | */ | |
702 | if (addr < text_section_addr_beg || addr > text_section_addr_end) { | |
703 | DBG("Address found is outside of the .text section addr=0x%zx, " | |
704 | ".text section=[0x%jd - 0x%jd].", addr, (intmax_t)text_section_addr_beg, | |
705 | (intmax_t)text_section_addr_end); | |
706 | ret = LTTNG_ERR_ELF_PARSING; | |
707 | goto error; | |
708 | } | |
709 | ||
710 | offset_in_section = addr - text_section_addr_beg; | |
711 | ||
712 | /* | |
713 | * Add the target offset in the text section to the offset of this text | |
714 | * section from the beginning of the binary file. | |
715 | */ | |
716 | *offset = text_section_offset + offset_in_section; | |
717 | ||
718 | error: | |
719 | return ret; | |
720 | } | |
721 | ||
722 | /* | |
723 | * Compute the offset of a symbol from the begining of the ELF binary. | |
724 | * | |
725 | * On success, returns 0 offset parameter is set to the computed value | |
726 | * On failure, returns -1. | |
727 | */ | |
728 | int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset) | |
729 | { | |
730 | int ret = 0; | |
731 | int sym_found = 0; | |
732 | int sym_count = 0; | |
733 | int sym_idx = 0; | |
734 | uint64_t addr = 0; | |
735 | char *curr_sym_str = NULL; | |
736 | char *symbol_table_data = NULL; | |
737 | char *string_table_data = NULL; | |
738 | struct lttng_elf_shdr *symtab_hdr = NULL; | |
739 | struct lttng_elf_shdr *strtab_hdr = NULL; | |
740 | struct lttng_elf *elf = NULL; | |
741 | ||
742 | if (!symbol || !offset ) { | |
743 | ret = LTTNG_ERR_ELF_PARSING; | |
744 | goto end; | |
745 | } | |
746 | ||
747 | elf = lttng_elf_create(fd); | |
748 | if (!elf) { | |
749 | ret = LTTNG_ERR_ELF_PARSING; | |
750 | goto end; | |
751 | } | |
752 | ||
753 | /* Get the symbol table section header. */ | |
754 | ret = lttng_elf_get_section_hdr_by_name(elf, SYMBOL_TAB_SECTION_NAME, | |
755 | &symtab_hdr); | |
756 | if (ret) { | |
757 | DBG("Cannot get ELF Symbol Table section."); | |
758 | ret = LTTNG_ERR_ELF_PARSING; | |
759 | goto destroy_elf; | |
760 | } | |
761 | /* Get the data associated with the symbol table section. */ | |
762 | symbol_table_data = lttng_elf_get_section_data(elf, symtab_hdr); | |
763 | if (symbol_table_data == NULL) { | |
764 | DBG("Cannot get ELF Symbol Table data."); | |
765 | ret = LTTNG_ERR_ELF_PARSING; | |
766 | goto destroy_elf; | |
767 | } | |
768 | ||
769 | /* Get the string table section header. */ | |
770 | ret = lttng_elf_get_section_hdr_by_name(elf, STRING_TAB_SECTION_NAME, | |
771 | &strtab_hdr); | |
772 | if (ret) { | |
773 | DBG("Cannot get ELF string table section."); | |
774 | goto free_symbol_table_data; | |
775 | } | |
776 | ||
777 | /* Get the data associated with the string table section. */ | |
778 | string_table_data = lttng_elf_get_section_data(elf, strtab_hdr); | |
779 | if (string_table_data == NULL) { | |
780 | DBG("Cannot get ELF string table section data."); | |
781 | ret = LTTNG_ERR_ELF_PARSING; | |
782 | goto free_symbol_table_data; | |
783 | } | |
784 | ||
785 | /* Get the number of symbol in the table for the iteration. */ | |
786 | sym_count = symtab_hdr->sh_size / symtab_hdr->sh_entsize; | |
787 | ||
788 | /* Loop over all symbol. */ | |
789 | for (sym_idx = 0; sym_idx < sym_count; sym_idx++) { | |
790 | struct lttng_elf_sym curr_sym; | |
791 | ||
792 | /* Get the symbol at the current index. */ | |
793 | if (is_elf_32_bit(elf)) { | |
794 | Elf32_Sym tmp = ((Elf32_Sym *) symbol_table_data)[sym_idx]; | |
795 | copy_sym(tmp, curr_sym); | |
796 | } else { | |
797 | Elf64_Sym tmp = ((Elf64_Sym *) symbol_table_data)[sym_idx]; | |
798 | copy_sym(tmp, curr_sym); | |
799 | } | |
800 | ||
801 | /* | |
802 | * If the st_name field is zero, there is no string name for | |
803 | * this symbol; skip to the next symbol. | |
804 | */ | |
805 | if (curr_sym.st_name == 0) { | |
806 | continue; | |
807 | } | |
808 | ||
809 | /* | |
810 | * Use the st_name field in the lttng_elf_sym struct to get offset of | |
811 | * the symbol's name from the beginning of the string table. | |
812 | */ | |
813 | curr_sym_str = string_table_data + curr_sym.st_name; | |
814 | ||
815 | /* | |
816 | * If the current symbol is not a function; skip to the next symbol. | |
817 | */ | |
818 | if (ELF_ST_TYPE(curr_sym.st_info) != STT_FUNC) { | |
819 | continue; | |
820 | } | |
821 | ||
822 | /* | |
823 | * Compare with the search symbol. If there is a match set the address | |
824 | * output parameter and return success. | |
825 | */ | |
826 | if (strcmp(symbol, curr_sym_str) == 0 ) { | |
827 | sym_found = 1; | |
828 | addr = curr_sym.st_value; | |
829 | break; | |
830 | } | |
831 | } | |
832 | ||
833 | if (!sym_found) { | |
834 | DBG("Symbol not found."); | |
835 | ret = LTTNG_ERR_ELF_PARSING; | |
836 | goto free_string_table_data; | |
837 | } | |
838 | ||
839 | /* | |
840 | * Use the virtual address of the symbol to compute the offset of this | |
841 | * symbol from the beginning of the executable file. | |
842 | */ | |
843 | ret = lttng_elf_convert_addr_in_text_to_offset(elf, addr, offset); | |
844 | if (ret) { | |
845 | DBG("Cannot convet addr to offset."); | |
846 | goto free_string_table_data; | |
847 | } | |
848 | ||
849 | ||
850 | free_string_table_data: | |
851 | free(string_table_data); | |
852 | free_symbol_table_data: | |
853 | free(symbol_table_data); | |
854 | destroy_elf: | |
855 | lttng_elf_destroy(elf); | |
856 | end: | |
857 | return ret; | |
858 | } |