Commit | Line | Data |
---|---|---|
d0927b41 | 1 | /* |
ab5be9fa MJ |
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> | |
d0927b41 | 5 | * |
ab5be9fa | 6 | * SPDX-License-Identifier: LGPL-2.1-or-later |
d0927b41 | 7 | * |
d0927b41 FD |
8 | */ |
9 | ||
10 | #include <common/compat/endian.h> | |
11 | #include <common/error.h> | |
12 | #include <common/lttng-elf.h> | |
13 | #include <common/macros.h> | |
14 | #include <common/readwrite.h> | |
15 | #include <fcntl.h> | |
16 | #include <stdbool.h> | |
17 | #include <stdint.h> | |
18 | #include <stdlib.h> | |
19 | #include <string.h> | |
20 | #include <sys/stat.h> | |
21 | #include <sys/types.h> | |
22 | #include <unistd.h> | |
23 | ||
24 | #include <elf.h> | |
25 | ||
26 | #define BUF_LEN 4096 | |
27 | #define TEXT_SECTION_NAME ".text" | |
28 | #define SYMBOL_TAB_SECTION_NAME ".symtab" | |
29 | #define STRING_TAB_SECTION_NAME ".strtab" | |
ef3dfe5d FD |
30 | #define DYNAMIC_SYMBOL_TAB_SECTION_NAME ".dynsym" |
31 | #define DYNAMIC_STRING_TAB_SECTION_NAME ".dynstr" | |
d0927b41 FD |
32 | #define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt" |
33 | #define NOTE_STAPSDT_NAME "stapsdt" | |
34 | #define NOTE_STAPSDT_TYPE 3 | |
b7e59a88 | 35 | #define MAX_SECTION_DATA_SIZE 512 * 1024 * 1024 |
d0927b41 FD |
36 | |
37 | #if BYTE_ORDER == LITTLE_ENDIAN | |
38 | #define NATIVE_ELF_ENDIANNESS ELFDATA2LSB | |
39 | #else | |
40 | #define NATIVE_ELF_ENDIANNESS ELFDATA2MSB | |
41 | #endif | |
42 | ||
8bd52288 FD |
43 | #define next_4bytes_boundary(x) (typeof(x)) ((((uint64_t)x) + 3) & ~0x03) |
44 | ||
d0927b41 FD |
45 | #define bswap(x) \ |
46 | do { \ | |
47 | switch (sizeof(x)) { \ | |
48 | case 8: \ | |
b1b34226 | 49 | x = be64toh((uint64_t)x); \ |
d0927b41 FD |
50 | break; \ |
51 | case 4: \ | |
b1b34226 | 52 | x = be32toh((uint32_t)x); \ |
d0927b41 FD |
53 | break; \ |
54 | case 2: \ | |
b1b34226 | 55 | x = be16toh((uint16_t)x); \ |
d0927b41 FD |
56 | break; \ |
57 | case 1: \ | |
58 | break; \ | |
59 | default: \ | |
60 | abort(); \ | |
61 | } \ | |
62 | } while (0) | |
63 | ||
64 | #define bswap_shdr(shdr) \ | |
65 | do { \ | |
66 | bswap((shdr).sh_name); \ | |
67 | bswap((shdr).sh_type); \ | |
68 | bswap((shdr).sh_flags); \ | |
69 | bswap((shdr).sh_addr); \ | |
70 | bswap((shdr).sh_offset); \ | |
71 | bswap((shdr).sh_size); \ | |
72 | bswap((shdr).sh_link); \ | |
73 | bswap((shdr).sh_info); \ | |
74 | bswap((shdr).sh_addralign); \ | |
75 | bswap((shdr).sh_entsize); \ | |
76 | } while (0) | |
77 | ||
78 | #define bswap_ehdr(ehdr) \ | |
79 | do { \ | |
80 | bswap((ehdr).e_type); \ | |
81 | bswap((ehdr).e_machine); \ | |
82 | bswap((ehdr).e_version); \ | |
83 | bswap((ehdr).e_entry); \ | |
84 | bswap((ehdr).e_phoff); \ | |
85 | bswap((ehdr).e_shoff); \ | |
86 | bswap((ehdr).e_flags); \ | |
87 | bswap((ehdr).e_ehsize); \ | |
88 | bswap((ehdr).e_phentsize); \ | |
89 | bswap((ehdr).e_phnum); \ | |
90 | bswap((ehdr).e_shentsize); \ | |
91 | bswap((ehdr).e_shnum); \ | |
92 | bswap((ehdr).e_shstrndx); \ | |
93 | } while (0) | |
94 | ||
95 | #define copy_shdr(src_shdr, dst_shdr) \ | |
96 | do { \ | |
97 | (dst_shdr).sh_name = (src_shdr).sh_name; \ | |
98 | (dst_shdr).sh_type = (src_shdr).sh_type; \ | |
99 | (dst_shdr).sh_flags = (src_shdr).sh_flags; \ | |
100 | (dst_shdr).sh_addr = (src_shdr).sh_addr; \ | |
101 | (dst_shdr).sh_offset = (src_shdr).sh_offset; \ | |
102 | (dst_shdr).sh_size = (src_shdr).sh_size; \ | |
103 | (dst_shdr).sh_link = (src_shdr).sh_link; \ | |
104 | (dst_shdr).sh_info = (src_shdr).sh_info; \ | |
105 | (dst_shdr).sh_addralign = (src_shdr).sh_addralign; \ | |
106 | (dst_shdr).sh_entsize = (src_shdr).sh_entsize; \ | |
107 | } while (0) | |
108 | ||
109 | #define copy_ehdr(src_ehdr, dst_ehdr) \ | |
110 | do { \ | |
111 | (dst_ehdr).e_type = (src_ehdr).e_type; \ | |
112 | (dst_ehdr).e_machine = (src_ehdr).e_machine; \ | |
113 | (dst_ehdr).e_version = (src_ehdr).e_version; \ | |
114 | (dst_ehdr).e_entry = (src_ehdr).e_entry; \ | |
115 | (dst_ehdr).e_phoff = (src_ehdr).e_phoff; \ | |
116 | (dst_ehdr).e_shoff = (src_ehdr).e_shoff; \ | |
117 | (dst_ehdr).e_flags = (src_ehdr).e_flags; \ | |
118 | (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize; \ | |
119 | (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize; \ | |
120 | (dst_ehdr).e_phnum = (src_ehdr).e_phnum; \ | |
121 | (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize; \ | |
122 | (dst_ehdr).e_shnum = (src_ehdr).e_shnum; \ | |
123 | (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx; \ | |
124 | } while (0) | |
125 | ||
126 | #define copy_sym(src_sym, dst_sym) \ | |
127 | do { \ | |
128 | dst_sym.st_name = src_sym.st_name; \ | |
129 | dst_sym.st_info = src_sym.st_info; \ | |
130 | dst_sym.st_other = src_sym.st_other; \ | |
131 | dst_sym.st_shndx = src_sym.st_shndx; \ | |
132 | dst_sym.st_value = src_sym.st_value; \ | |
133 | dst_sym.st_size = src_sym.st_size; \ | |
134 | } while (0) | |
135 | ||
136 | /* Both 32bit and 64bit use the same 1 byte field for type. (See elf.h) */ | |
137 | #define ELF_ST_TYPE(val) ELF32_ST_TYPE(val) | |
138 | ||
139 | struct lttng_elf_ehdr { | |
140 | uint16_t e_type; | |
141 | uint16_t e_machine; | |
142 | uint32_t e_version; | |
143 | uint64_t e_entry; | |
144 | uint64_t e_phoff; | |
145 | uint64_t e_shoff; | |
146 | uint32_t e_flags; | |
147 | uint16_t e_ehsize; | |
148 | uint16_t e_phentsize; | |
149 | uint16_t e_phnum; | |
150 | uint16_t e_shentsize; | |
151 | uint16_t e_shnum; | |
152 | uint16_t e_shstrndx; | |
153 | }; | |
154 | ||
155 | struct lttng_elf_shdr { | |
156 | uint32_t sh_name; | |
157 | uint32_t sh_type; | |
158 | uint64_t sh_flags; | |
159 | uint64_t sh_addr; | |
160 | uint64_t sh_offset; | |
161 | uint64_t sh_size; | |
162 | uint32_t sh_link; | |
163 | uint32_t sh_info; | |
164 | uint64_t sh_addralign; | |
165 | uint64_t sh_entsize; | |
166 | }; | |
167 | ||
168 | /* | |
169 | * This struct can hold both 32bit and 64bit symbol description. It's used with | |
170 | * the copy_sym() macro. Using this abstraction, we can use the same code for | |
171 | * both bitness. | |
172 | */ | |
173 | struct lttng_elf_sym { | |
174 | uint32_t st_name; | |
175 | uint8_t st_info; | |
176 | uint8_t st_other; | |
177 | uint16_t st_shndx; | |
178 | uint64_t st_value; | |
179 | uint64_t st_size; | |
180 | }; | |
181 | ||
182 | struct lttng_elf { | |
183 | int fd; | |
b7e59a88 | 184 | size_t file_size; |
d0927b41 FD |
185 | uint8_t bitness; |
186 | uint8_t endianness; | |
187 | /* Offset in bytes to start of section names string table. */ | |
188 | off_t section_names_offset; | |
189 | /* Size in bytes of section names string table. */ | |
190 | size_t section_names_size; | |
191 | struct lttng_elf_ehdr *ehdr; | |
192 | }; | |
193 | ||
194 | static inline | |
195 | int is_elf_32_bit(struct lttng_elf *elf) | |
196 | { | |
197 | return elf->bitness == ELFCLASS32; | |
198 | } | |
199 | ||
200 | static inline | |
201 | int is_elf_native_endian(struct lttng_elf *elf) | |
202 | { | |
203 | return elf->endianness == NATIVE_ELF_ENDIANNESS; | |
204 | } | |
205 | ||
206 | static | |
207 | int populate_section_header(struct lttng_elf * elf, struct lttng_elf_shdr *shdr, | |
208 | uint32_t index) | |
209 | { | |
210 | int ret = 0; | |
211 | off_t offset; | |
212 | ||
213 | /* Compute the offset of the section in the file */ | |
214 | offset = (off_t) elf->ehdr->e_shoff | |
215 | + (off_t) index * elf->ehdr->e_shentsize; | |
216 | ||
217 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { | |
218 | PERROR("Error seeking to the beginning of ELF section header"); | |
219 | ret = -1; | |
220 | goto error; | |
221 | } | |
222 | ||
223 | if (is_elf_32_bit(elf)) { | |
224 | Elf32_Shdr elf_shdr; | |
225 | ||
226 | if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) { | |
227 | PERROR("Error reading ELF section header"); | |
228 | ret = -1; | |
229 | goto error; | |
230 | } | |
231 | if (!is_elf_native_endian(elf)) { | |
232 | bswap_shdr(elf_shdr); | |
233 | } | |
234 | copy_shdr(elf_shdr, *shdr); | |
235 | } else { | |
236 | Elf64_Shdr elf_shdr; | |
237 | ||
238 | if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) { | |
239 | PERROR("Error reading ELF section header"); | |
240 | ret = -1; | |
241 | goto error; | |
242 | } | |
243 | if (!is_elf_native_endian(elf)) { | |
244 | bswap_shdr(elf_shdr); | |
245 | } | |
246 | copy_shdr(elf_shdr, *shdr); | |
247 | } | |
248 | ||
249 | error: | |
250 | return ret; | |
251 | } | |
252 | ||
253 | static | |
254 | int populate_elf_header(struct lttng_elf *elf) | |
255 | { | |
256 | int ret = 0; | |
257 | ||
258 | /* | |
259 | * Move the read pointer back to the beginning to read the full header | |
260 | * and copy it in our structure. | |
261 | */ | |
262 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
263 | PERROR("Error seeking to the beginning of the file"); | |
264 | ret = -1; | |
265 | goto error; | |
266 | } | |
267 | ||
268 | /* | |
269 | * Use macros to set fields in the ELF header struct for both 32bit and | |
270 | * 64bit. | |
271 | */ | |
272 | if (is_elf_32_bit(elf)) { | |
273 | Elf32_Ehdr elf_ehdr; | |
274 | ||
275 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
276 | ret = -1; | |
277 | goto error; | |
278 | } | |
279 | if (!is_elf_native_endian(elf)) { | |
280 | bswap_ehdr(elf_ehdr); | |
281 | } | |
282 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
283 | } else { | |
284 | Elf64_Ehdr elf_ehdr; | |
285 | ||
286 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
287 | ret = -1; | |
288 | goto error; | |
289 | } | |
290 | if (!is_elf_native_endian(elf)) { | |
291 | bswap_ehdr(elf_ehdr); | |
292 | } | |
293 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
294 | } | |
295 | error: | |
296 | return ret; | |
297 | } | |
298 | ||
299 | /* | |
300 | * Retrieve the nth (where n is the `index` argument) shdr (section | |
301 | * header) from the given elf instance. | |
302 | * | |
22fae25a | 303 | * 0 is returned on succes, -1 on failure. |
d0927b41 FD |
304 | */ |
305 | static | |
22fae25a JG |
306 | int lttng_elf_get_section_hdr(struct lttng_elf *elf, |
307 | uint16_t index, struct lttng_elf_shdr *out_header) | |
d0927b41 | 308 | { |
d0927b41 FD |
309 | int ret = 0; |
310 | ||
311 | if (!elf) { | |
22fae25a | 312 | ret = -1; |
d0927b41 FD |
313 | goto error; |
314 | } | |
315 | ||
316 | if (index >= elf->ehdr->e_shnum) { | |
22fae25a | 317 | ret = -1; |
d0927b41 FD |
318 | goto error; |
319 | } | |
320 | ||
22fae25a | 321 | ret = populate_section_header(elf, out_header, index); |
d0927b41 | 322 | if (ret) { |
d0927b41 FD |
323 | DBG("Error populating section header."); |
324 | goto error; | |
325 | } | |
d0927b41 FD |
326 | |
327 | error: | |
22fae25a | 328 | return ret; |
d0927b41 FD |
329 | } |
330 | ||
331 | /* | |
332 | * Lookup a section's name from a given offset (usually from an shdr's | |
333 | * sh_name value) in bytes relative to the beginning of the section | |
334 | * names string table. | |
335 | * | |
336 | * If no name is found, NULL is returned. | |
337 | */ | |
338 | static | |
339 | char *lttng_elf_get_section_name(struct lttng_elf *elf, off_t offset) | |
340 | { | |
341 | char *name = NULL; | |
342 | size_t name_length = 0, to_read; /* name_length does not include \0 */ | |
343 | ||
344 | if (!elf) { | |
345 | goto error; | |
346 | } | |
347 | ||
348 | if (offset >= elf->section_names_size) { | |
349 | goto error; | |
350 | } | |
351 | ||
352 | if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) { | |
353 | PERROR("Error seeking to the beginning of ELF string table section"); | |
354 | goto error; | |
355 | } | |
356 | ||
357 | to_read = elf->section_names_size - offset; | |
358 | ||
359 | /* Find first \0 after or at current location, remember name_length. */ | |
360 | for (;;) { | |
361 | char buf[BUF_LEN]; | |
362 | ssize_t read_len; | |
363 | size_t i; | |
364 | ||
365 | if (!to_read) { | |
366 | goto error; | |
367 | } | |
368 | read_len = lttng_read(elf->fd, buf, min_t(size_t, BUF_LEN, to_read)); | |
369 | if (read_len <= 0) { | |
370 | PERROR("Error reading ELF string table section"); | |
371 | goto error; | |
372 | } | |
373 | for (i = 0; i < read_len; i++) { | |
374 | if (buf[i] == '\0') { | |
375 | name_length += i; | |
376 | goto end; | |
377 | } | |
378 | } | |
379 | name_length += read_len; | |
380 | to_read -= read_len; | |
381 | } | |
382 | end: | |
383 | /* | |
384 | * We found the length of the section name, now seek back to the | |
385 | * beginning of the name and copy it in the newly allocated buffer. | |
386 | */ | |
387 | name = zmalloc(sizeof(char) * (name_length + 1)); /* + 1 for \0 */ | |
388 | if (!name) { | |
389 | PERROR("Error allocating ELF section name buffer"); | |
390 | goto error; | |
391 | } | |
392 | if (lseek(elf->fd, elf->section_names_offset + offset, SEEK_SET) < 0) { | |
393 | PERROR("Error seeking to the offset of the ELF section name"); | |
394 | goto error; | |
395 | } | |
396 | if (lttng_read(elf->fd, name, name_length + 1) < name_length + 1) { | |
397 | PERROR("Error reading the ELF section name"); | |
398 | goto error; | |
399 | } | |
400 | ||
401 | return name; | |
402 | ||
403 | error: | |
404 | free(name); | |
405 | return NULL; | |
406 | } | |
407 | ||
408 | static | |
409 | int lttng_elf_validate_and_populate(struct lttng_elf *elf) | |
410 | { | |
411 | uint8_t version; | |
412 | uint8_t e_ident[EI_NIDENT]; | |
413 | uint8_t *magic_number = NULL; | |
414 | int ret = 0; | |
415 | ||
416 | if (elf->fd == -1) { | |
417 | DBG("fd error"); | |
418 | ret = LTTNG_ERR_ELF_PARSING; | |
419 | goto end; | |
420 | } | |
421 | ||
422 | /* | |
423 | * First read the magic number, endianness and version to later populate | |
424 | * the ELF header with the correct endianness and bitness. | |
425 | * (see elf.h) | |
426 | */ | |
427 | ||
428 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
429 | PERROR("Error seeking the beginning of ELF file"); | |
430 | ret = LTTNG_ERR_ELF_PARSING; | |
431 | goto end; | |
432 | } | |
433 | ret = lttng_read(elf->fd, e_ident, EI_NIDENT); | |
434 | if (ret < EI_NIDENT) { | |
435 | DBG("Error reading the ELF identification fields"); | |
436 | if (ret == -1) { | |
437 | PERROR("Error reading the ELF identification fields"); | |
438 | } | |
439 | ret = LTTNG_ERR_ELF_PARSING; | |
440 | goto end; | |
441 | } | |
442 | ||
443 | /* | |
444 | * Copy fields used to check that the target file is in fact a valid ELF | |
445 | * file. | |
446 | */ | |
447 | elf->bitness = e_ident[EI_CLASS]; | |
448 | elf->endianness = e_ident[EI_DATA]; | |
449 | version = e_ident[EI_VERSION]; | |
450 | magic_number = &e_ident[EI_MAG0]; | |
451 | ||
452 | /* | |
453 | * Check the magic number. | |
454 | */ | |
455 | if (memcmp(magic_number, ELFMAG, SELFMAG) != 0) { | |
456 | DBG("Error check ELF magic number."); | |
457 | ret = LTTNG_ERR_ELF_PARSING; | |
458 | goto end; | |
459 | } | |
460 | ||
461 | /* | |
462 | * Check the bitness is either ELFCLASS32 or ELFCLASS64. | |
463 | */ | |
464 | if (elf->bitness <= ELFCLASSNONE || elf->bitness >= ELFCLASSNUM) { | |
465 | DBG("ELF class error."); | |
466 | ret = LTTNG_ERR_ELF_PARSING; | |
467 | goto end; | |
468 | } | |
469 | ||
470 | /* | |
471 | * Check the endianness is either ELFDATA2LSB or ELFDATA2MSB. | |
472 | */ | |
473 | if (elf->endianness <= ELFDATANONE || elf->endianness >= ELFDATANUM) { | |
474 | DBG("ELF endianness error."); | |
475 | ret = LTTNG_ERR_ELF_PARSING; | |
476 | goto end; | |
477 | } | |
478 | ||
479 | /* | |
480 | * Check the version is ELF_CURRENT. | |
481 | */ | |
482 | if (version <= EV_NONE || version >= EV_NUM) { | |
483 | DBG("Wrong ELF version."); | |
484 | ret = LTTNG_ERR_ELF_PARSING; | |
485 | goto end; | |
486 | } | |
487 | ||
488 | elf->ehdr = zmalloc(sizeof(struct lttng_elf_ehdr)); | |
489 | if (!elf->ehdr) { | |
490 | PERROR("Error allocation buffer for ELF header"); | |
491 | ret = LTTNG_ERR_NOMEM; | |
492 | goto end; | |
493 | } | |
494 | ||
495 | /* | |
496 | * Copy the content of the elf header. | |
497 | */ | |
498 | ret = populate_elf_header(elf); | |
499 | if (ret) { | |
500 | DBG("Error reading ELF header,"); | |
501 | goto free_elf_error; | |
502 | } | |
503 | ||
504 | goto end; | |
505 | ||
506 | free_elf_error: | |
507 | free(elf->ehdr); | |
508 | elf->ehdr = NULL; | |
509 | end: | |
510 | return ret; | |
511 | } | |
512 | ||
513 | /* | |
514 | * Create an instance of lttng_elf for the ELF file located at | |
515 | * `path`. | |
516 | * | |
517 | * Return a pointer to the instance on success, NULL on failure. | |
518 | */ | |
519 | static | |
520 | struct lttng_elf *lttng_elf_create(int fd) | |
521 | { | |
22fae25a | 522 | struct lttng_elf_shdr section_names_shdr; |
d0927b41 FD |
523 | struct lttng_elf *elf = NULL; |
524 | int ret; | |
b7e59a88 | 525 | struct stat stat_buf; |
d0927b41 FD |
526 | |
527 | if (fd < 0) { | |
528 | goto error; | |
529 | } | |
530 | ||
b7e59a88 JG |
531 | ret = fstat(fd, &stat_buf); |
532 | if (ret) { | |
533 | PERROR("Failed to determine size of elf file"); | |
534 | goto error; | |
535 | } | |
536 | if (!S_ISREG(stat_buf.st_mode)) { | |
537 | ERR("Refusing to initialize lttng_elf from non-regular file"); | |
538 | goto error; | |
539 | } | |
540 | ||
d0927b41 FD |
541 | elf = zmalloc(sizeof(struct lttng_elf)); |
542 | if (!elf) { | |
543 | PERROR("Error allocating struct lttng_elf"); | |
544 | goto error; | |
545 | } | |
b7e59a88 | 546 | elf->file_size = (size_t) stat_buf.st_size; |
d0927b41 FD |
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 | ||
22fae25a JG |
559 | ret = lttng_elf_get_section_hdr( |
560 | elf, elf->ehdr->e_shstrndx, §ion_names_shdr); | |
561 | if (ret) { | |
d0927b41 FD |
562 | goto error; |
563 | } | |
564 | ||
22fae25a JG |
565 | elf->section_names_offset = section_names_shdr.sh_offset; |
566 | elf->section_names_size = section_names_shdr.sh_size; | |
d0927b41 FD |
567 | return elf; |
568 | ||
569 | error: | |
570 | if (elf) { | |
571 | if (elf->ehdr) { | |
572 | free(elf->ehdr); | |
573 | } | |
574 | if (elf->fd >= 0) { | |
575 | if (close(elf->fd)) { | |
576 | PERROR("Error closing file descriptor in error path"); | |
577 | abort(); | |
578 | } | |
579 | } | |
580 | free(elf); | |
581 | } | |
582 | return NULL; | |
583 | } | |
584 | ||
585 | /* | |
586 | * Destroy the given lttng_elf instance. | |
587 | */ | |
588 | static | |
589 | void lttng_elf_destroy(struct lttng_elf *elf) | |
590 | { | |
591 | if (!elf) { | |
592 | return; | |
593 | } | |
594 | ||
595 | free(elf->ehdr); | |
596 | if (close(elf->fd)) { | |
597 | PERROR("Error closing file description in error path"); | |
598 | abort(); | |
599 | } | |
600 | free(elf); | |
601 | } | |
602 | ||
603 | static | |
604 | int lttng_elf_get_section_hdr_by_name(struct lttng_elf *elf, | |
22fae25a | 605 | const char *section_name, struct lttng_elf_shdr *section_hdr) |
d0927b41 FD |
606 | { |
607 | int i; | |
608 | char *curr_section_name; | |
22fae25a | 609 | |
d0927b41 | 610 | for (i = 0; i < elf->ehdr->e_shnum; ++i) { |
4e0b99ca | 611 | bool name_equal; |
22fae25a | 612 | int ret = lttng_elf_get_section_hdr(elf, i, section_hdr); |
d0927b41 | 613 | |
22fae25a JG |
614 | if (ret) { |
615 | break; | |
616 | } | |
617 | curr_section_name = lttng_elf_get_section_name(elf, | |
618 | section_hdr->sh_name); | |
d0927b41 FD |
619 | if (!curr_section_name) { |
620 | continue; | |
621 | } | |
4e0b99ca JG |
622 | name_equal = strcmp(curr_section_name, section_name) == 0; |
623 | free(curr_section_name); | |
624 | if (name_equal) { | |
d0927b41 FD |
625 | return 0; |
626 | } | |
627 | } | |
628 | return LTTNG_ERR_ELF_PARSING; | |
629 | } | |
630 | ||
631 | static | |
632 | char *lttng_elf_get_section_data(struct lttng_elf *elf, | |
633 | struct lttng_elf_shdr *shdr) | |
634 | { | |
635 | int ret; | |
636 | off_t section_offset; | |
637 | char *data; | |
ee5b998f | 638 | size_t max_alloc_size; |
d0927b41 FD |
639 | |
640 | if (!elf || !shdr) { | |
641 | goto error; | |
642 | } | |
643 | ||
ee5b998f FD |
644 | max_alloc_size = min_t(size_t, MAX_SECTION_DATA_SIZE, elf->file_size); |
645 | ||
d0927b41 FD |
646 | section_offset = shdr->sh_offset; |
647 | if (lseek(elf->fd, section_offset, SEEK_SET) < 0) { | |
648 | PERROR("Error seeking to section offset"); | |
649 | goto error; | |
650 | } | |
651 | ||
b7e59a88 JG |
652 | if (shdr->sh_size > max_alloc_size) { |
653 | ERR("ELF section size exceeds maximal allowed size of %zu bytes", | |
654 | max_alloc_size); | |
655 | goto error; | |
656 | } | |
d0927b41 FD |
657 | data = zmalloc(shdr->sh_size); |
658 | if (!data) { | |
659 | PERROR("Error allocating buffer for ELF section data"); | |
660 | goto error; | |
661 | } | |
662 | ret = lttng_read(elf->fd, data, shdr->sh_size); | |
663 | if (ret == -1) { | |
664 | PERROR("Error reading ELF section data"); | |
665 | goto free_error; | |
666 | } | |
667 | ||
668 | return data; | |
669 | ||
670 | free_error: | |
671 | free(data); | |
672 | error: | |
673 | return NULL; | |
674 | } | |
675 | ||
676 | /* | |
677 | * Convert the virtual address in a binary's mapping to the offset of | |
678 | * the corresponding instruction in the binary file. | |
679 | * This function assumes the address is in the text section. | |
680 | * | |
681 | * Returns the offset on success or non-zero in case of failure. | |
682 | */ | |
683 | static | |
684 | int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle, | |
685 | size_t addr, uint64_t *offset) | |
686 | { | |
687 | int ret = 0; | |
688 | off_t text_section_offset; | |
689 | off_t text_section_addr_beg; | |
690 | off_t text_section_addr_end; | |
691 | off_t offset_in_section; | |
22fae25a | 692 | struct lttng_elf_shdr text_section_hdr; |
d0927b41 FD |
693 | |
694 | if (!elf_handle) { | |
695 | DBG("Invalid ELF handle."); | |
696 | ret = LTTNG_ERR_ELF_PARSING; | |
697 | goto error; | |
698 | } | |
699 | ||
700 | /* Get a pointer to the .text section header. */ | |
701 | ret = lttng_elf_get_section_hdr_by_name(elf_handle, | |
702 | TEXT_SECTION_NAME, &text_section_hdr); | |
703 | if (ret) { | |
704 | DBG("Text section not found in binary."); | |
705 | ret = LTTNG_ERR_ELF_PARSING; | |
706 | goto error; | |
707 | } | |
708 | ||
22fae25a JG |
709 | text_section_offset = text_section_hdr.sh_offset; |
710 | text_section_addr_beg = text_section_hdr.sh_addr; | |
711 | text_section_addr_end = | |
712 | text_section_addr_beg + text_section_hdr.sh_size; | |
d0927b41 FD |
713 | |
714 | /* | |
715 | * Verify that the address is within the .text section boundaries. | |
716 | */ | |
717 | if (addr < text_section_addr_beg || addr > text_section_addr_end) { | |
718 | DBG("Address found is outside of the .text section addr=0x%zx, " | |
719 | ".text section=[0x%jd - 0x%jd].", addr, (intmax_t)text_section_addr_beg, | |
720 | (intmax_t)text_section_addr_end); | |
721 | ret = LTTNG_ERR_ELF_PARSING; | |
722 | goto error; | |
723 | } | |
724 | ||
725 | offset_in_section = addr - text_section_addr_beg; | |
726 | ||
727 | /* | |
728 | * Add the target offset in the text section to the offset of this text | |
729 | * section from the beginning of the binary file. | |
730 | */ | |
731 | *offset = text_section_offset + offset_in_section; | |
732 | ||
733 | error: | |
734 | return ret; | |
735 | } | |
736 | ||
737 | /* | |
738 | * Compute the offset of a symbol from the begining of the ELF binary. | |
739 | * | |
740 | * On success, returns 0 offset parameter is set to the computed value | |
741 | * On failure, returns -1. | |
742 | */ | |
743 | int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset) | |
744 | { | |
745 | int ret = 0; | |
746 | int sym_found = 0; | |
747 | int sym_count = 0; | |
748 | int sym_idx = 0; | |
749 | uint64_t addr = 0; | |
750 | char *curr_sym_str = NULL; | |
751 | char *symbol_table_data = NULL; | |
752 | char *string_table_data = NULL; | |
b53d4e59 | 753 | const char *string_table_name = NULL; |
22fae25a JG |
754 | struct lttng_elf_shdr symtab_hdr; |
755 | struct lttng_elf_shdr strtab_hdr; | |
d0927b41 FD |
756 | struct lttng_elf *elf = NULL; |
757 | ||
758 | if (!symbol || !offset ) { | |
759 | ret = LTTNG_ERR_ELF_PARSING; | |
760 | goto end; | |
761 | } | |
762 | ||
763 | elf = lttng_elf_create(fd); | |
764 | if (!elf) { | |
765 | ret = LTTNG_ERR_ELF_PARSING; | |
766 | goto end; | |
767 | } | |
768 | ||
ef3dfe5d FD |
769 | /* |
770 | * The .symtab section might not exist on stripped binaries. | |
771 | * Try to get the symbol table section header first. If it's absent, | |
772 | * try to get the dynamic symbol table. All symbols in the dynamic | |
773 | * symbol tab are in the (normal) symbol table if it exists. | |
774 | */ | |
d0927b41 FD |
775 | ret = lttng_elf_get_section_hdr_by_name(elf, SYMBOL_TAB_SECTION_NAME, |
776 | &symtab_hdr); | |
777 | if (ret) { | |
ef3dfe5d FD |
778 | DBG("Cannot get ELF Symbol Table section. Trying to get ELF Dynamic Symbol Table section."); |
779 | /* Get the dynamic symbol table section header. */ | |
780 | ret = lttng_elf_get_section_hdr_by_name(elf, DYNAMIC_SYMBOL_TAB_SECTION_NAME, | |
781 | &symtab_hdr); | |
782 | if (ret) { | |
783 | DBG("Cannot get ELF Symbol Table nor Dynamic Symbol Table sections."); | |
784 | ret = LTTNG_ERR_ELF_PARSING; | |
785 | goto destroy_elf; | |
786 | } | |
787 | string_table_name = DYNAMIC_STRING_TAB_SECTION_NAME; | |
788 | } else { | |
789 | string_table_name = STRING_TAB_SECTION_NAME; | |
d0927b41 | 790 | } |
ef3dfe5d | 791 | |
d0927b41 | 792 | /* Get the data associated with the symbol table section. */ |
22fae25a | 793 | symbol_table_data = lttng_elf_get_section_data(elf, &symtab_hdr); |
d0927b41 FD |
794 | if (symbol_table_data == NULL) { |
795 | DBG("Cannot get ELF Symbol Table data."); | |
796 | ret = LTTNG_ERR_ELF_PARSING; | |
797 | goto destroy_elf; | |
798 | } | |
799 | ||
800 | /* Get the string table section header. */ | |
ef3dfe5d | 801 | ret = lttng_elf_get_section_hdr_by_name(elf, string_table_name, |
d0927b41 FD |
802 | &strtab_hdr); |
803 | if (ret) { | |
804 | DBG("Cannot get ELF string table section."); | |
805 | goto free_symbol_table_data; | |
806 | } | |
807 | ||
808 | /* Get the data associated with the string table section. */ | |
22fae25a | 809 | string_table_data = lttng_elf_get_section_data(elf, &strtab_hdr); |
d0927b41 FD |
810 | if (string_table_data == NULL) { |
811 | DBG("Cannot get ELF string table section data."); | |
812 | ret = LTTNG_ERR_ELF_PARSING; | |
813 | goto free_symbol_table_data; | |
814 | } | |
815 | ||
816 | /* Get the number of symbol in the table for the iteration. */ | |
22fae25a | 817 | sym_count = symtab_hdr.sh_size / symtab_hdr.sh_entsize; |
d0927b41 FD |
818 | |
819 | /* Loop over all symbol. */ | |
820 | for (sym_idx = 0; sym_idx < sym_count; sym_idx++) { | |
821 | struct lttng_elf_sym curr_sym; | |
822 | ||
823 | /* Get the symbol at the current index. */ | |
824 | if (is_elf_32_bit(elf)) { | |
825 | Elf32_Sym tmp = ((Elf32_Sym *) symbol_table_data)[sym_idx]; | |
826 | copy_sym(tmp, curr_sym); | |
827 | } else { | |
828 | Elf64_Sym tmp = ((Elf64_Sym *) symbol_table_data)[sym_idx]; | |
829 | copy_sym(tmp, curr_sym); | |
830 | } | |
831 | ||
832 | /* | |
833 | * If the st_name field is zero, there is no string name for | |
834 | * this symbol; skip to the next symbol. | |
835 | */ | |
836 | if (curr_sym.st_name == 0) { | |
837 | continue; | |
838 | } | |
839 | ||
840 | /* | |
841 | * Use the st_name field in the lttng_elf_sym struct to get offset of | |
842 | * the symbol's name from the beginning of the string table. | |
843 | */ | |
844 | curr_sym_str = string_table_data + curr_sym.st_name; | |
845 | ||
846 | /* | |
847 | * If the current symbol is not a function; skip to the next symbol. | |
848 | */ | |
849 | if (ELF_ST_TYPE(curr_sym.st_info) != STT_FUNC) { | |
850 | continue; | |
851 | } | |
852 | ||
853 | /* | |
854 | * Compare with the search symbol. If there is a match set the address | |
855 | * output parameter and return success. | |
856 | */ | |
857 | if (strcmp(symbol, curr_sym_str) == 0 ) { | |
858 | sym_found = 1; | |
859 | addr = curr_sym.st_value; | |
860 | break; | |
861 | } | |
862 | } | |
863 | ||
864 | if (!sym_found) { | |
865 | DBG("Symbol not found."); | |
866 | ret = LTTNG_ERR_ELF_PARSING; | |
867 | goto free_string_table_data; | |
868 | } | |
869 | ||
870 | /* | |
871 | * Use the virtual address of the symbol to compute the offset of this | |
872 | * symbol from the beginning of the executable file. | |
873 | */ | |
874 | ret = lttng_elf_convert_addr_in_text_to_offset(elf, addr, offset); | |
875 | if (ret) { | |
512df046 | 876 | DBG("Cannot convert addr to offset."); |
d0927b41 FD |
877 | goto free_string_table_data; |
878 | } | |
879 | ||
880 | ||
881 | free_string_table_data: | |
882 | free(string_table_data); | |
883 | free_symbol_table_data: | |
884 | free(symbol_table_data); | |
885 | destroy_elf: | |
886 | lttng_elf_destroy(elf); | |
887 | end: | |
888 | return ret; | |
889 | } | |
8bd52288 FD |
890 | |
891 | /* | |
892 | * Compute the offsets of SDT probes from the begining of the ELF binary. | |
893 | * | |
894 | * On success, returns 0 and the nb_probes parameter is set to the number of | |
895 | * offsets found and the offsets parameter points to an array of offsets where | |
896 | * the SDT probes are. | |
897 | * On failure, returns -1. | |
898 | */ | |
899 | int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name, | |
900 | const char *probe_name, uint64_t **offsets, uint32_t *nb_probes) | |
901 | { | |
902 | int ret = 0, nb_match = 0; | |
22fae25a | 903 | struct lttng_elf_shdr stap_note_section_hdr; |
8bd52288 FD |
904 | struct lttng_elf *elf = NULL; |
905 | char *stap_note_section_data = NULL; | |
906 | char *curr_note_section_begin, *curr_data_ptr, *curr_probe, *curr_provider; | |
d3be5495 | 907 | char *next_note_ptr; |
8bd52288 FD |
908 | uint32_t name_size, desc_size, note_type; |
909 | uint64_t curr_probe_location, curr_probe_offset, curr_semaphore_location; | |
910 | uint64_t *probe_locs = NULL, *new_probe_locs = NULL; | |
911 | ||
912 | if (!provider_name || !probe_name || !nb_probes || !offsets) { | |
913 | DBG("Invalid arguments."); | |
914 | ret = LTTNG_ERR_ELF_PARSING; | |
915 | goto error; | |
916 | } | |
917 | ||
918 | elf = lttng_elf_create(fd); | |
919 | if (!elf) { | |
920 | DBG("Error allocation ELF."); | |
921 | ret = LTTNG_ERR_ELF_PARSING; | |
922 | goto error; | |
923 | } | |
924 | ||
925 | /* Get the stap note section header. */ | |
926 | ret = lttng_elf_get_section_hdr_by_name(elf, NOTE_STAPSDT_SECTION_NAME, | |
927 | &stap_note_section_hdr); | |
928 | if (ret) { | |
929 | DBG("Cannot get ELF stap note section."); | |
930 | goto destroy_elf_error; | |
931 | } | |
932 | ||
933 | /* Get the data associated with the stap note section. */ | |
22fae25a JG |
934 | stap_note_section_data = |
935 | lttng_elf_get_section_data(elf, &stap_note_section_hdr); | |
8bd52288 FD |
936 | if (stap_note_section_data == NULL) { |
937 | DBG("Cannot get ELF stap note section data."); | |
938 | ret = LTTNG_ERR_ELF_PARSING; | |
939 | goto destroy_elf_error; | |
940 | } | |
941 | ||
8bd52288 FD |
942 | next_note_ptr = stap_note_section_data; |
943 | curr_note_section_begin = stap_note_section_data; | |
944 | ||
945 | *offsets = NULL; | |
946 | while (1) { | |
947 | curr_data_ptr = next_note_ptr; | |
948 | /* Check if we have reached the end of the note section. */ | |
949 | if (curr_data_ptr >= | |
22fae25a JG |
950 | curr_note_section_begin + |
951 | stap_note_section_hdr.sh_size) { | |
8bd52288 FD |
952 | *nb_probes = nb_match; |
953 | *offsets = probe_locs; | |
954 | ret = 0; | |
955 | break; | |
956 | } | |
957 | /* Get name size field. */ | |
958 | name_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr); | |
959 | curr_data_ptr += sizeof(uint32_t); | |
960 | ||
961 | /* Sanity check; a zero name_size is reserved. */ | |
962 | if (name_size == 0) { | |
963 | DBG("Invalid name size field in SDT probe descriptions" | |
964 | "section."); | |
965 | ret = -1; | |
966 | goto realloc_error; | |
967 | } | |
968 | ||
969 | /* Get description size field. */ | |
970 | desc_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr); | |
971 | curr_data_ptr += sizeof(uint32_t); | |
972 | ||
973 | /* Get type field. */ | |
974 | note_type = *(uint32_t *) curr_data_ptr; | |
975 | curr_data_ptr += sizeof(uint32_t); | |
976 | ||
977 | /* | |
978 | * Move the pointer to the next note to be ready for the next | |
979 | * iteration. The current note is made of 3 unsigned 32bit | |
980 | * integers (name size, descriptor size and note type), the | |
981 | * name and the descriptor. To move to the next note, we move | |
982 | * the pointer according to those values. | |
983 | */ | |
984 | next_note_ptr = next_note_ptr + | |
985 | (3 * sizeof(uint32_t)) + desc_size + name_size; | |
986 | ||
987 | /* | |
988 | * Move ptr to the end of the name string (we don't need it) | |
989 | * and go to the next 4 byte alignement. | |
990 | */ | |
991 | if (note_type != NOTE_STAPSDT_TYPE || | |
992 | strncmp(curr_data_ptr, NOTE_STAPSDT_NAME, name_size) != 0) { | |
993 | continue; | |
994 | } | |
995 | ||
996 | curr_data_ptr += name_size; | |
997 | ||
8bd52288 FD |
998 | /* Get probe location. */ |
999 | curr_probe_location = *(uint64_t *) curr_data_ptr; | |
1000 | curr_data_ptr += sizeof(uint64_t); | |
1001 | ||
1002 | /* Pass over the base. Not needed. */ | |
1003 | curr_data_ptr += sizeof(uint64_t); | |
1004 | ||
1005 | /* Get semaphore location. */ | |
1006 | curr_semaphore_location = *(uint64_t *) curr_data_ptr; | |
1007 | curr_data_ptr += sizeof(uint64_t); | |
1008 | /* Get provider name. */ | |
1009 | curr_provider = curr_data_ptr; | |
1010 | curr_data_ptr += strlen(curr_provider) + 1; | |
1011 | ||
1012 | /* Get probe name. */ | |
1013 | curr_probe = curr_data_ptr; | |
8bd52288 FD |
1014 | |
1015 | /* Check if the provider and probe name match */ | |
1016 | if (strcmp(provider_name, curr_provider) == 0 && | |
1017 | strcmp(probe_name, curr_probe) == 0) { | |
1018 | int new_size; | |
1019 | ||
1020 | /* | |
1021 | * We currently don't support SDT probes with semaphores. Return | |
1022 | * success as we found a matching probe but it's guarded by a | |
1023 | * semaphore. | |
1024 | */ | |
1025 | if (curr_semaphore_location != 0) { | |
1026 | ret = LTTNG_ERR_SDT_PROBE_SEMAPHORE; | |
09f3038c | 1027 | goto realloc_error; |
8bd52288 FD |
1028 | } |
1029 | ||
1030 | new_size = (++nb_match) * sizeof(uint64_t); | |
1031 | ||
1032 | /* | |
1033 | * Found a match with not semaphore, we need to copy the | |
1034 | * probe_location to the output parameter. | |
1035 | */ | |
1036 | new_probe_locs = realloc(probe_locs, new_size); | |
1037 | if (!new_probe_locs) { | |
1038 | /* Error allocating a larger buffer */ | |
1039 | DBG("Allocation error in SDT."); | |
1040 | ret = LTTNG_ERR_NOMEM; | |
1041 | goto realloc_error; | |
1042 | } | |
1043 | probe_locs = new_probe_locs; | |
1044 | new_probe_locs = NULL; | |
1045 | ||
1046 | /* | |
1047 | * Use the virtual address of the probe to compute the offset of | |
1048 | * this probe from the beginning of the executable file. | |
1049 | */ | |
1050 | ret = lttng_elf_convert_addr_in_text_to_offset(elf, | |
1051 | curr_probe_location, &curr_probe_offset); | |
1052 | if (ret) { | |
1053 | DBG("Conversion error in SDT."); | |
1054 | goto realloc_error; | |
1055 | } | |
1056 | ||
1057 | probe_locs[nb_match - 1] = curr_probe_offset; | |
1058 | } | |
1059 | } | |
1060 | ||
1061 | end: | |
1062 | free(stap_note_section_data); | |
1063 | destroy_elf_error: | |
1064 | lttng_elf_destroy(elf); | |
1065 | error: | |
1066 | return ret; | |
1067 | realloc_error: | |
1068 | free(probe_locs); | |
1069 | goto end; | |
1070 | } |