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 | ||
a6bc4ca9 | 10 | #include <algorithm> |
c9e313bc SM |
11 | #include <common/compat/endian.hpp> |
12 | #include <common/error.hpp> | |
13 | #include <common/lttng-elf.hpp> | |
14 | #include <common/macros.hpp> | |
15 | #include <common/readwrite.hpp> | |
d0927b41 FD |
16 | #include <fcntl.h> |
17 | #include <stdbool.h> | |
18 | #include <stdint.h> | |
19 | #include <stdlib.h> | |
20 | #include <string.h> | |
21 | #include <sys/stat.h> | |
22 | #include <sys/types.h> | |
23 | #include <unistd.h> | |
24 | ||
25 | #include <elf.h> | |
26 | ||
27 | #define BUF_LEN 4096 | |
28 | #define TEXT_SECTION_NAME ".text" | |
29 | #define SYMBOL_TAB_SECTION_NAME ".symtab" | |
30 | #define STRING_TAB_SECTION_NAME ".strtab" | |
ef3dfe5d FD |
31 | #define DYNAMIC_SYMBOL_TAB_SECTION_NAME ".dynsym" |
32 | #define DYNAMIC_STRING_TAB_SECTION_NAME ".dynstr" | |
d0927b41 FD |
33 | #define NOTE_STAPSDT_SECTION_NAME ".note.stapsdt" |
34 | #define NOTE_STAPSDT_NAME "stapsdt" | |
35 | #define NOTE_STAPSDT_TYPE 3 | |
b7e59a88 | 36 | #define MAX_SECTION_DATA_SIZE 512 * 1024 * 1024 |
d0927b41 FD |
37 | |
38 | #if BYTE_ORDER == LITTLE_ENDIAN | |
39 | #define NATIVE_ELF_ENDIANNESS ELFDATA2LSB | |
40 | #else | |
41 | #define NATIVE_ELF_ENDIANNESS ELFDATA2MSB | |
42 | #endif | |
43 | ||
8bd52288 FD |
44 | #define next_4bytes_boundary(x) (typeof(x)) ((((uint64_t)x) + 3) & ~0x03) |
45 | ||
d0927b41 FD |
46 | #define bswap(x) \ |
47 | do { \ | |
48 | switch (sizeof(x)) { \ | |
49 | case 8: \ | |
b1b34226 | 50 | x = be64toh((uint64_t)x); \ |
d0927b41 FD |
51 | break; \ |
52 | case 4: \ | |
b1b34226 | 53 | x = be32toh((uint32_t)x); \ |
d0927b41 FD |
54 | break; \ |
55 | case 2: \ | |
b1b34226 | 56 | x = be16toh((uint16_t)x); \ |
d0927b41 FD |
57 | break; \ |
58 | case 1: \ | |
59 | break; \ | |
60 | default: \ | |
61 | abort(); \ | |
62 | } \ | |
63 | } while (0) | |
64 | ||
65 | #define bswap_shdr(shdr) \ | |
66 | do { \ | |
67 | bswap((shdr).sh_name); \ | |
68 | bswap((shdr).sh_type); \ | |
69 | bswap((shdr).sh_flags); \ | |
70 | bswap((shdr).sh_addr); \ | |
71 | bswap((shdr).sh_offset); \ | |
72 | bswap((shdr).sh_size); \ | |
73 | bswap((shdr).sh_link); \ | |
74 | bswap((shdr).sh_info); \ | |
75 | bswap((shdr).sh_addralign); \ | |
76 | bswap((shdr).sh_entsize); \ | |
77 | } while (0) | |
78 | ||
79 | #define bswap_ehdr(ehdr) \ | |
80 | do { \ | |
81 | bswap((ehdr).e_type); \ | |
82 | bswap((ehdr).e_machine); \ | |
83 | bswap((ehdr).e_version); \ | |
84 | bswap((ehdr).e_entry); \ | |
85 | bswap((ehdr).e_phoff); \ | |
86 | bswap((ehdr).e_shoff); \ | |
87 | bswap((ehdr).e_flags); \ | |
88 | bswap((ehdr).e_ehsize); \ | |
89 | bswap((ehdr).e_phentsize); \ | |
90 | bswap((ehdr).e_phnum); \ | |
91 | bswap((ehdr).e_shentsize); \ | |
92 | bswap((ehdr).e_shnum); \ | |
93 | bswap((ehdr).e_shstrndx); \ | |
94 | } while (0) | |
95 | ||
96 | #define copy_shdr(src_shdr, dst_shdr) \ | |
97 | do { \ | |
98 | (dst_shdr).sh_name = (src_shdr).sh_name; \ | |
99 | (dst_shdr).sh_type = (src_shdr).sh_type; \ | |
100 | (dst_shdr).sh_flags = (src_shdr).sh_flags; \ | |
101 | (dst_shdr).sh_addr = (src_shdr).sh_addr; \ | |
102 | (dst_shdr).sh_offset = (src_shdr).sh_offset; \ | |
103 | (dst_shdr).sh_size = (src_shdr).sh_size; \ | |
104 | (dst_shdr).sh_link = (src_shdr).sh_link; \ | |
105 | (dst_shdr).sh_info = (src_shdr).sh_info; \ | |
106 | (dst_shdr).sh_addralign = (src_shdr).sh_addralign; \ | |
107 | (dst_shdr).sh_entsize = (src_shdr).sh_entsize; \ | |
108 | } while (0) | |
109 | ||
110 | #define copy_ehdr(src_ehdr, dst_ehdr) \ | |
111 | do { \ | |
112 | (dst_ehdr).e_type = (src_ehdr).e_type; \ | |
113 | (dst_ehdr).e_machine = (src_ehdr).e_machine; \ | |
114 | (dst_ehdr).e_version = (src_ehdr).e_version; \ | |
115 | (dst_ehdr).e_entry = (src_ehdr).e_entry; \ | |
116 | (dst_ehdr).e_phoff = (src_ehdr).e_phoff; \ | |
117 | (dst_ehdr).e_shoff = (src_ehdr).e_shoff; \ | |
118 | (dst_ehdr).e_flags = (src_ehdr).e_flags; \ | |
119 | (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize; \ | |
120 | (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize; \ | |
121 | (dst_ehdr).e_phnum = (src_ehdr).e_phnum; \ | |
122 | (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize; \ | |
123 | (dst_ehdr).e_shnum = (src_ehdr).e_shnum; \ | |
124 | (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx; \ | |
125 | } while (0) | |
126 | ||
127 | #define copy_sym(src_sym, dst_sym) \ | |
128 | do { \ | |
129 | dst_sym.st_name = src_sym.st_name; \ | |
130 | dst_sym.st_info = src_sym.st_info; \ | |
131 | dst_sym.st_other = src_sym.st_other; \ | |
132 | dst_sym.st_shndx = src_sym.st_shndx; \ | |
133 | dst_sym.st_value = src_sym.st_value; \ | |
134 | dst_sym.st_size = src_sym.st_size; \ | |
135 | } while (0) | |
136 | ||
983a481e MJ |
137 | #ifndef ELFCLASSNUM |
138 | #define ELFCLASSNUM 3 | |
139 | #endif | |
140 | ||
141 | #ifndef ELFDATANUM | |
142 | #define ELFDATANUM 3 | |
143 | #endif | |
144 | ||
145 | #ifndef EV_NUM | |
146 | #define EV_NUM 2 | |
147 | #endif | |
d0927b41 | 148 | |
f1494934 | 149 | namespace { |
d0927b41 FD |
150 | struct lttng_elf_ehdr { |
151 | uint16_t e_type; | |
152 | uint16_t e_machine; | |
153 | uint32_t e_version; | |
154 | uint64_t e_entry; | |
155 | uint64_t e_phoff; | |
156 | uint64_t e_shoff; | |
157 | uint32_t e_flags; | |
158 | uint16_t e_ehsize; | |
159 | uint16_t e_phentsize; | |
160 | uint16_t e_phnum; | |
161 | uint16_t e_shentsize; | |
162 | uint16_t e_shnum; | |
163 | uint16_t e_shstrndx; | |
164 | }; | |
165 | ||
166 | struct lttng_elf_shdr { | |
167 | uint32_t sh_name; | |
168 | uint32_t sh_type; | |
169 | uint64_t sh_flags; | |
170 | uint64_t sh_addr; | |
171 | uint64_t sh_offset; | |
172 | uint64_t sh_size; | |
173 | uint32_t sh_link; | |
174 | uint32_t sh_info; | |
175 | uint64_t sh_addralign; | |
176 | uint64_t sh_entsize; | |
177 | }; | |
178 | ||
179 | /* | |
180 | * This struct can hold both 32bit and 64bit symbol description. It's used with | |
181 | * the copy_sym() macro. Using this abstraction, we can use the same code for | |
182 | * both bitness. | |
183 | */ | |
184 | struct lttng_elf_sym { | |
185 | uint32_t st_name; | |
186 | uint8_t st_info; | |
187 | uint8_t st_other; | |
188 | uint16_t st_shndx; | |
189 | uint64_t st_value; | |
190 | uint64_t st_size; | |
191 | }; | |
f1494934 | 192 | } /* namespace */ |
d0927b41 FD |
193 | |
194 | struct lttng_elf { | |
195 | int fd; | |
b7e59a88 | 196 | size_t file_size; |
d0927b41 FD |
197 | uint8_t bitness; |
198 | uint8_t endianness; | |
199 | /* Offset in bytes to start of section names string table. */ | |
200 | off_t section_names_offset; | |
201 | /* Size in bytes of section names string table. */ | |
202 | size_t section_names_size; | |
203 | struct lttng_elf_ehdr *ehdr; | |
204 | }; | |
205 | ||
206 | static inline | |
207 | int is_elf_32_bit(struct lttng_elf *elf) | |
208 | { | |
209 | return elf->bitness == ELFCLASS32; | |
210 | } | |
211 | ||
212 | static inline | |
213 | int is_elf_native_endian(struct lttng_elf *elf) | |
214 | { | |
215 | return elf->endianness == NATIVE_ELF_ENDIANNESS; | |
216 | } | |
217 | ||
218 | static | |
219 | int populate_section_header(struct lttng_elf * elf, struct lttng_elf_shdr *shdr, | |
220 | uint32_t index) | |
221 | { | |
222 | int ret = 0; | |
223 | off_t offset; | |
224 | ||
225 | /* Compute the offset of the section in the file */ | |
226 | offset = (off_t) elf->ehdr->e_shoff | |
227 | + (off_t) index * elf->ehdr->e_shentsize; | |
228 | ||
229 | if (lseek(elf->fd, offset, SEEK_SET) < 0) { | |
230 | PERROR("Error seeking to the beginning of ELF section header"); | |
231 | ret = -1; | |
232 | goto error; | |
233 | } | |
234 | ||
235 | if (is_elf_32_bit(elf)) { | |
236 | Elf32_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 | } else { | |
248 | Elf64_Shdr elf_shdr; | |
249 | ||
250 | if (lttng_read(elf->fd, &elf_shdr, sizeof(elf_shdr)) < sizeof(elf_shdr)) { | |
251 | PERROR("Error reading ELF section header"); | |
252 | ret = -1; | |
253 | goto error; | |
254 | } | |
255 | if (!is_elf_native_endian(elf)) { | |
256 | bswap_shdr(elf_shdr); | |
257 | } | |
258 | copy_shdr(elf_shdr, *shdr); | |
259 | } | |
260 | ||
261 | error: | |
262 | return ret; | |
263 | } | |
264 | ||
265 | static | |
266 | int populate_elf_header(struct lttng_elf *elf) | |
267 | { | |
268 | int ret = 0; | |
269 | ||
270 | /* | |
271 | * Move the read pointer back to the beginning to read the full header | |
272 | * and copy it in our structure. | |
273 | */ | |
274 | if (lseek(elf->fd, 0, SEEK_SET) < 0) { | |
275 | PERROR("Error seeking to the beginning of the file"); | |
276 | ret = -1; | |
277 | goto error; | |
278 | } | |
279 | ||
280 | /* | |
281 | * Use macros to set fields in the ELF header struct for both 32bit and | |
282 | * 64bit. | |
283 | */ | |
284 | if (is_elf_32_bit(elf)) { | |
285 | Elf32_Ehdr elf_ehdr; | |
286 | ||
287 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
288 | ret = -1; | |
289 | goto error; | |
290 | } | |
291 | if (!is_elf_native_endian(elf)) { | |
292 | bswap_ehdr(elf_ehdr); | |
293 | } | |
294 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
295 | } else { | |
296 | Elf64_Ehdr elf_ehdr; | |
297 | ||
298 | if (lttng_read(elf->fd, &elf_ehdr, sizeof(elf_ehdr)) < sizeof(elf_ehdr)) { | |
299 | ret = -1; | |
300 | goto error; | |
301 | } | |
302 | if (!is_elf_native_endian(elf)) { | |
303 | bswap_ehdr(elf_ehdr); | |
304 | } | |
305 | copy_ehdr(elf_ehdr, *(elf->ehdr)); | |
306 | } | |
307 | error: | |
308 | return ret; | |
309 | } | |
310 | ||
311 | /* | |
312 | * Retrieve the nth (where n is the `index` argument) shdr (section | |
313 | * header) from the given elf instance. | |
314 | * | |
22fae25a | 315 | * 0 is returned on succes, -1 on failure. |
d0927b41 FD |
316 | */ |
317 | static | |
22fae25a JG |
318 | int lttng_elf_get_section_hdr(struct lttng_elf *elf, |
319 | uint16_t index, struct lttng_elf_shdr *out_header) | |
d0927b41 | 320 | { |
d0927b41 FD |
321 | int ret = 0; |
322 | ||
323 | if (!elf) { | |
22fae25a | 324 | ret = -1; |
d0927b41 FD |
325 | goto error; |
326 | } | |
327 | ||
328 | if (index >= elf->ehdr->e_shnum) { | |
22fae25a | 329 | ret = -1; |
d0927b41 FD |
330 | goto error; |
331 | } | |
332 | ||
22fae25a | 333 | ret = populate_section_header(elf, out_header, index); |
d0927b41 | 334 | if (ret) { |
d0927b41 FD |
335 | DBG("Error populating section header."); |
336 | goto error; | |
337 | } | |
d0927b41 FD |
338 | |
339 | error: | |
22fae25a | 340 | return ret; |
d0927b41 FD |
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 | } | |
a6bc4ca9 | 380 | read_len = lttng_read(elf->fd, buf, std::min<size_t>(BUF_LEN, to_read)); |
d0927b41 FD |
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 | */ | |
64803277 | 399 | name = calloc<char>((name_length + 1)); /* + 1 for \0 */ |
d0927b41 FD |
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 | ||
64803277 | 500 | elf->ehdr = zmalloc<lttng_elf_ehdr>(); |
d0927b41 FD |
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 | { | |
22fae25a | 534 | struct lttng_elf_shdr section_names_shdr; |
d0927b41 FD |
535 | struct lttng_elf *elf = NULL; |
536 | int ret; | |
b7e59a88 | 537 | struct stat stat_buf; |
d0927b41 FD |
538 | |
539 | if (fd < 0) { | |
540 | goto error; | |
541 | } | |
542 | ||
b7e59a88 JG |
543 | ret = fstat(fd, &stat_buf); |
544 | if (ret) { | |
545 | PERROR("Failed to determine size of elf file"); | |
546 | goto error; | |
547 | } | |
548 | if (!S_ISREG(stat_buf.st_mode)) { | |
549 | ERR("Refusing to initialize lttng_elf from non-regular file"); | |
550 | goto error; | |
551 | } | |
552 | ||
64803277 | 553 | elf = zmalloc<lttng_elf>(); |
d0927b41 FD |
554 | if (!elf) { |
555 | PERROR("Error allocating struct lttng_elf"); | |
556 | goto error; | |
557 | } | |
b7e59a88 | 558 | elf->file_size = (size_t) stat_buf.st_size; |
d0927b41 FD |
559 | |
560 | elf->fd = dup(fd); | |
561 | if (elf->fd < 0) { | |
562 | PERROR("Error duplicating file descriptor to binary"); | |
563 | goto error; | |
564 | } | |
565 | ||
566 | ret = lttng_elf_validate_and_populate(elf); | |
567 | if (ret) { | |
568 | goto error; | |
569 | } | |
570 | ||
22fae25a JG |
571 | ret = lttng_elf_get_section_hdr( |
572 | elf, elf->ehdr->e_shstrndx, §ion_names_shdr); | |
573 | if (ret) { | |
d0927b41 FD |
574 | goto error; |
575 | } | |
576 | ||
22fae25a JG |
577 | elf->section_names_offset = section_names_shdr.sh_offset; |
578 | elf->section_names_size = section_names_shdr.sh_size; | |
d0927b41 FD |
579 | return elf; |
580 | ||
581 | error: | |
582 | if (elf) { | |
583 | if (elf->ehdr) { | |
584 | free(elf->ehdr); | |
585 | } | |
586 | if (elf->fd >= 0) { | |
587 | if (close(elf->fd)) { | |
588 | PERROR("Error closing file descriptor in error path"); | |
589 | abort(); | |
590 | } | |
591 | } | |
592 | free(elf); | |
593 | } | |
594 | return NULL; | |
595 | } | |
596 | ||
597 | /* | |
598 | * Destroy the given lttng_elf instance. | |
599 | */ | |
600 | static | |
601 | void lttng_elf_destroy(struct lttng_elf *elf) | |
602 | { | |
603 | if (!elf) { | |
604 | return; | |
605 | } | |
606 | ||
607 | free(elf->ehdr); | |
608 | if (close(elf->fd)) { | |
609 | PERROR("Error closing file description in error path"); | |
610 | abort(); | |
611 | } | |
612 | free(elf); | |
613 | } | |
614 | ||
615 | static | |
616 | int lttng_elf_get_section_hdr_by_name(struct lttng_elf *elf, | |
22fae25a | 617 | const char *section_name, struct lttng_elf_shdr *section_hdr) |
d0927b41 FD |
618 | { |
619 | int i; | |
620 | char *curr_section_name; | |
22fae25a | 621 | |
d0927b41 | 622 | for (i = 0; i < elf->ehdr->e_shnum; ++i) { |
4e0b99ca | 623 | bool name_equal; |
22fae25a | 624 | int ret = lttng_elf_get_section_hdr(elf, i, section_hdr); |
d0927b41 | 625 | |
22fae25a JG |
626 | if (ret) { |
627 | break; | |
628 | } | |
629 | curr_section_name = lttng_elf_get_section_name(elf, | |
630 | section_hdr->sh_name); | |
d0927b41 FD |
631 | if (!curr_section_name) { |
632 | continue; | |
633 | } | |
4e0b99ca JG |
634 | name_equal = strcmp(curr_section_name, section_name) == 0; |
635 | free(curr_section_name); | |
636 | if (name_equal) { | |
d0927b41 FD |
637 | return 0; |
638 | } | |
639 | } | |
640 | return LTTNG_ERR_ELF_PARSING; | |
641 | } | |
642 | ||
643 | static | |
644 | char *lttng_elf_get_section_data(struct lttng_elf *elf, | |
645 | struct lttng_elf_shdr *shdr) | |
646 | { | |
647 | int ret; | |
648 | off_t section_offset; | |
649 | char *data; | |
ee5b998f | 650 | size_t max_alloc_size; |
d0927b41 FD |
651 | |
652 | if (!elf || !shdr) { | |
653 | goto error; | |
654 | } | |
655 | ||
a6bc4ca9 | 656 | max_alloc_size = std::min<size_t>(MAX_SECTION_DATA_SIZE, elf->file_size); |
ee5b998f | 657 | |
d0927b41 FD |
658 | section_offset = shdr->sh_offset; |
659 | if (lseek(elf->fd, section_offset, SEEK_SET) < 0) { | |
660 | PERROR("Error seeking to section offset"); | |
661 | goto error; | |
662 | } | |
663 | ||
b7e59a88 JG |
664 | if (shdr->sh_size > max_alloc_size) { |
665 | ERR("ELF section size exceeds maximal allowed size of %zu bytes", | |
666 | max_alloc_size); | |
667 | goto error; | |
668 | } | |
64803277 | 669 | data = calloc<char>(shdr->sh_size); |
d0927b41 FD |
670 | if (!data) { |
671 | PERROR("Error allocating buffer for ELF section data"); | |
672 | goto error; | |
673 | } | |
674 | ret = lttng_read(elf->fd, data, shdr->sh_size); | |
675 | if (ret == -1) { | |
676 | PERROR("Error reading ELF section data"); | |
677 | goto free_error; | |
678 | } | |
679 | ||
680 | return data; | |
681 | ||
682 | free_error: | |
683 | free(data); | |
684 | error: | |
685 | return NULL; | |
686 | } | |
687 | ||
688 | /* | |
689 | * Convert the virtual address in a binary's mapping to the offset of | |
690 | * the corresponding instruction in the binary file. | |
691 | * This function assumes the address is in the text section. | |
692 | * | |
693 | * Returns the offset on success or non-zero in case of failure. | |
694 | */ | |
695 | static | |
696 | int lttng_elf_convert_addr_in_text_to_offset(struct lttng_elf *elf_handle, | |
697 | size_t addr, uint64_t *offset) | |
698 | { | |
699 | int ret = 0; | |
700 | off_t text_section_offset; | |
701 | off_t text_section_addr_beg; | |
702 | off_t text_section_addr_end; | |
703 | off_t offset_in_section; | |
22fae25a | 704 | struct lttng_elf_shdr text_section_hdr; |
d0927b41 FD |
705 | |
706 | if (!elf_handle) { | |
707 | DBG("Invalid ELF handle."); | |
708 | ret = LTTNG_ERR_ELF_PARSING; | |
709 | goto error; | |
710 | } | |
711 | ||
712 | /* Get a pointer to the .text section header. */ | |
713 | ret = lttng_elf_get_section_hdr_by_name(elf_handle, | |
714 | TEXT_SECTION_NAME, &text_section_hdr); | |
715 | if (ret) { | |
716 | DBG("Text section not found in binary."); | |
717 | ret = LTTNG_ERR_ELF_PARSING; | |
718 | goto error; | |
719 | } | |
720 | ||
22fae25a JG |
721 | text_section_offset = text_section_hdr.sh_offset; |
722 | text_section_addr_beg = text_section_hdr.sh_addr; | |
723 | text_section_addr_end = | |
724 | text_section_addr_beg + text_section_hdr.sh_size; | |
d0927b41 FD |
725 | |
726 | /* | |
727 | * Verify that the address is within the .text section boundaries. | |
728 | */ | |
729 | if (addr < text_section_addr_beg || addr > text_section_addr_end) { | |
730 | DBG("Address found is outside of the .text section addr=0x%zx, " | |
731 | ".text section=[0x%jd - 0x%jd].", addr, (intmax_t)text_section_addr_beg, | |
732 | (intmax_t)text_section_addr_end); | |
733 | ret = LTTNG_ERR_ELF_PARSING; | |
734 | goto error; | |
735 | } | |
736 | ||
737 | offset_in_section = addr - text_section_addr_beg; | |
738 | ||
739 | /* | |
740 | * Add the target offset in the text section to the offset of this text | |
741 | * section from the beginning of the binary file. | |
742 | */ | |
743 | *offset = text_section_offset + offset_in_section; | |
744 | ||
745 | error: | |
746 | return ret; | |
747 | } | |
748 | ||
749 | /* | |
750 | * Compute the offset of a symbol from the begining of the ELF binary. | |
751 | * | |
752 | * On success, returns 0 offset parameter is set to the computed value | |
753 | * On failure, returns -1. | |
754 | */ | |
755 | int lttng_elf_get_symbol_offset(int fd, char *symbol, uint64_t *offset) | |
756 | { | |
757 | int ret = 0; | |
758 | int sym_found = 0; | |
759 | int sym_count = 0; | |
760 | int sym_idx = 0; | |
761 | uint64_t addr = 0; | |
762 | char *curr_sym_str = NULL; | |
763 | char *symbol_table_data = NULL; | |
764 | char *string_table_data = NULL; | |
b53d4e59 | 765 | const char *string_table_name = NULL; |
22fae25a JG |
766 | struct lttng_elf_shdr symtab_hdr; |
767 | struct lttng_elf_shdr strtab_hdr; | |
d0927b41 FD |
768 | struct lttng_elf *elf = NULL; |
769 | ||
770 | if (!symbol || !offset ) { | |
771 | ret = LTTNG_ERR_ELF_PARSING; | |
772 | goto end; | |
773 | } | |
774 | ||
775 | elf = lttng_elf_create(fd); | |
776 | if (!elf) { | |
777 | ret = LTTNG_ERR_ELF_PARSING; | |
778 | goto end; | |
779 | } | |
780 | ||
ef3dfe5d FD |
781 | /* |
782 | * The .symtab section might not exist on stripped binaries. | |
783 | * Try to get the symbol table section header first. If it's absent, | |
784 | * try to get the dynamic symbol table. All symbols in the dynamic | |
785 | * symbol tab are in the (normal) symbol table if it exists. | |
786 | */ | |
d0927b41 FD |
787 | ret = lttng_elf_get_section_hdr_by_name(elf, SYMBOL_TAB_SECTION_NAME, |
788 | &symtab_hdr); | |
789 | if (ret) { | |
ef3dfe5d FD |
790 | DBG("Cannot get ELF Symbol Table section. Trying to get ELF Dynamic Symbol Table section."); |
791 | /* Get the dynamic symbol table section header. */ | |
792 | ret = lttng_elf_get_section_hdr_by_name(elf, DYNAMIC_SYMBOL_TAB_SECTION_NAME, | |
793 | &symtab_hdr); | |
794 | if (ret) { | |
795 | DBG("Cannot get ELF Symbol Table nor Dynamic Symbol Table sections."); | |
796 | ret = LTTNG_ERR_ELF_PARSING; | |
797 | goto destroy_elf; | |
798 | } | |
799 | string_table_name = DYNAMIC_STRING_TAB_SECTION_NAME; | |
800 | } else { | |
801 | string_table_name = STRING_TAB_SECTION_NAME; | |
d0927b41 | 802 | } |
ef3dfe5d | 803 | |
d0927b41 | 804 | /* Get the data associated with the symbol table section. */ |
22fae25a | 805 | symbol_table_data = lttng_elf_get_section_data(elf, &symtab_hdr); |
d0927b41 FD |
806 | if (symbol_table_data == NULL) { |
807 | DBG("Cannot get ELF Symbol Table data."); | |
808 | ret = LTTNG_ERR_ELF_PARSING; | |
809 | goto destroy_elf; | |
810 | } | |
811 | ||
812 | /* Get the string table section header. */ | |
ef3dfe5d | 813 | ret = lttng_elf_get_section_hdr_by_name(elf, string_table_name, |
d0927b41 FD |
814 | &strtab_hdr); |
815 | if (ret) { | |
816 | DBG("Cannot get ELF string table section."); | |
817 | goto free_symbol_table_data; | |
818 | } | |
819 | ||
820 | /* Get the data associated with the string table section. */ | |
22fae25a | 821 | string_table_data = lttng_elf_get_section_data(elf, &strtab_hdr); |
d0927b41 FD |
822 | if (string_table_data == NULL) { |
823 | DBG("Cannot get ELF string table section data."); | |
824 | ret = LTTNG_ERR_ELF_PARSING; | |
825 | goto free_symbol_table_data; | |
826 | } | |
827 | ||
828 | /* Get the number of symbol in the table for the iteration. */ | |
a395e079 JG |
829 | if (symtab_hdr.sh_entsize == 0) { |
830 | DBG("Invalid ELF string table entry size."); | |
831 | ret = LTTNG_ERR_ELF_PARSING; | |
3308655a | 832 | goto free_string_table_data; |
a395e079 JG |
833 | } |
834 | ||
22fae25a | 835 | sym_count = symtab_hdr.sh_size / symtab_hdr.sh_entsize; |
d0927b41 FD |
836 | |
837 | /* Loop over all symbol. */ | |
838 | for (sym_idx = 0; sym_idx < sym_count; sym_idx++) { | |
839 | struct lttng_elf_sym curr_sym; | |
840 | ||
841 | /* Get the symbol at the current index. */ | |
842 | if (is_elf_32_bit(elf)) { | |
843 | Elf32_Sym tmp = ((Elf32_Sym *) symbol_table_data)[sym_idx]; | |
844 | copy_sym(tmp, curr_sym); | |
845 | } else { | |
846 | Elf64_Sym tmp = ((Elf64_Sym *) symbol_table_data)[sym_idx]; | |
847 | copy_sym(tmp, curr_sym); | |
848 | } | |
849 | ||
850 | /* | |
851 | * If the st_name field is zero, there is no string name for | |
852 | * this symbol; skip to the next symbol. | |
853 | */ | |
854 | if (curr_sym.st_name == 0) { | |
855 | continue; | |
856 | } | |
857 | ||
858 | /* | |
859 | * Use the st_name field in the lttng_elf_sym struct to get offset of | |
860 | * the symbol's name from the beginning of the string table. | |
861 | */ | |
862 | curr_sym_str = string_table_data + curr_sym.st_name; | |
863 | ||
864 | /* | |
865 | * If the current symbol is not a function; skip to the next symbol. | |
866 | */ | |
983a481e MJ |
867 | /* Both 32bit and 64bit use the same 1 byte field for type. (See elf.h) */ |
868 | if (ELF32_ST_TYPE(curr_sym.st_info) != STT_FUNC) { | |
d0927b41 FD |
869 | continue; |
870 | } | |
871 | ||
872 | /* | |
873 | * Compare with the search symbol. If there is a match set the address | |
874 | * output parameter and return success. | |
875 | */ | |
876 | if (strcmp(symbol, curr_sym_str) == 0 ) { | |
877 | sym_found = 1; | |
878 | addr = curr_sym.st_value; | |
879 | break; | |
880 | } | |
881 | } | |
882 | ||
883 | if (!sym_found) { | |
884 | DBG("Symbol not found."); | |
885 | ret = LTTNG_ERR_ELF_PARSING; | |
886 | goto free_string_table_data; | |
887 | } | |
888 | ||
889 | /* | |
890 | * Use the virtual address of the symbol to compute the offset of this | |
891 | * symbol from the beginning of the executable file. | |
892 | */ | |
893 | ret = lttng_elf_convert_addr_in_text_to_offset(elf, addr, offset); | |
894 | if (ret) { | |
512df046 | 895 | DBG("Cannot convert addr to offset."); |
d0927b41 FD |
896 | goto free_string_table_data; |
897 | } | |
898 | ||
899 | ||
900 | free_string_table_data: | |
901 | free(string_table_data); | |
902 | free_symbol_table_data: | |
903 | free(symbol_table_data); | |
904 | destroy_elf: | |
905 | lttng_elf_destroy(elf); | |
906 | end: | |
907 | return ret; | |
908 | } | |
8bd52288 FD |
909 | |
910 | /* | |
911 | * Compute the offsets of SDT probes from the begining of the ELF binary. | |
912 | * | |
913 | * On success, returns 0 and the nb_probes parameter is set to the number of | |
914 | * offsets found and the offsets parameter points to an array of offsets where | |
915 | * the SDT probes are. | |
916 | * On failure, returns -1. | |
917 | */ | |
918 | int lttng_elf_get_sdt_probe_offsets(int fd, const char *provider_name, | |
919 | const char *probe_name, uint64_t **offsets, uint32_t *nb_probes) | |
920 | { | |
921 | int ret = 0, nb_match = 0; | |
22fae25a | 922 | struct lttng_elf_shdr stap_note_section_hdr; |
8bd52288 FD |
923 | struct lttng_elf *elf = NULL; |
924 | char *stap_note_section_data = NULL; | |
925 | char *curr_note_section_begin, *curr_data_ptr, *curr_probe, *curr_provider; | |
d3be5495 | 926 | char *next_note_ptr; |
8bd52288 FD |
927 | uint32_t name_size, desc_size, note_type; |
928 | uint64_t curr_probe_location, curr_probe_offset, curr_semaphore_location; | |
929 | uint64_t *probe_locs = NULL, *new_probe_locs = NULL; | |
930 | ||
931 | if (!provider_name || !probe_name || !nb_probes || !offsets) { | |
932 | DBG("Invalid arguments."); | |
933 | ret = LTTNG_ERR_ELF_PARSING; | |
934 | goto error; | |
935 | } | |
936 | ||
937 | elf = lttng_elf_create(fd); | |
938 | if (!elf) { | |
939 | DBG("Error allocation ELF."); | |
940 | ret = LTTNG_ERR_ELF_PARSING; | |
941 | goto error; | |
942 | } | |
943 | ||
944 | /* Get the stap note section header. */ | |
945 | ret = lttng_elf_get_section_hdr_by_name(elf, NOTE_STAPSDT_SECTION_NAME, | |
946 | &stap_note_section_hdr); | |
947 | if (ret) { | |
948 | DBG("Cannot get ELF stap note section."); | |
949 | goto destroy_elf_error; | |
950 | } | |
951 | ||
952 | /* Get the data associated with the stap note section. */ | |
22fae25a JG |
953 | stap_note_section_data = |
954 | lttng_elf_get_section_data(elf, &stap_note_section_hdr); | |
8bd52288 FD |
955 | if (stap_note_section_data == NULL) { |
956 | DBG("Cannot get ELF stap note section data."); | |
957 | ret = LTTNG_ERR_ELF_PARSING; | |
958 | goto destroy_elf_error; | |
959 | } | |
960 | ||
8bd52288 FD |
961 | next_note_ptr = stap_note_section_data; |
962 | curr_note_section_begin = stap_note_section_data; | |
963 | ||
964 | *offsets = NULL; | |
965 | while (1) { | |
966 | curr_data_ptr = next_note_ptr; | |
967 | /* Check if we have reached the end of the note section. */ | |
968 | if (curr_data_ptr >= | |
22fae25a JG |
969 | curr_note_section_begin + |
970 | stap_note_section_hdr.sh_size) { | |
8bd52288 FD |
971 | *nb_probes = nb_match; |
972 | *offsets = probe_locs; | |
973 | ret = 0; | |
974 | break; | |
975 | } | |
976 | /* Get name size field. */ | |
977 | name_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr); | |
978 | curr_data_ptr += sizeof(uint32_t); | |
979 | ||
980 | /* Sanity check; a zero name_size is reserved. */ | |
981 | if (name_size == 0) { | |
982 | DBG("Invalid name size field in SDT probe descriptions" | |
983 | "section."); | |
984 | ret = -1; | |
985 | goto realloc_error; | |
986 | } | |
987 | ||
988 | /* Get description size field. */ | |
989 | desc_size = next_4bytes_boundary(*(uint32_t*) curr_data_ptr); | |
990 | curr_data_ptr += sizeof(uint32_t); | |
991 | ||
992 | /* Get type field. */ | |
993 | note_type = *(uint32_t *) curr_data_ptr; | |
994 | curr_data_ptr += sizeof(uint32_t); | |
995 | ||
996 | /* | |
997 | * Move the pointer to the next note to be ready for the next | |
998 | * iteration. The current note is made of 3 unsigned 32bit | |
999 | * integers (name size, descriptor size and note type), the | |
1000 | * name and the descriptor. To move to the next note, we move | |
1001 | * the pointer according to those values. | |
1002 | */ | |
1003 | next_note_ptr = next_note_ptr + | |
1004 | (3 * sizeof(uint32_t)) + desc_size + name_size; | |
1005 | ||
1006 | /* | |
1007 | * Move ptr to the end of the name string (we don't need it) | |
1008 | * and go to the next 4 byte alignement. | |
1009 | */ | |
1010 | if (note_type != NOTE_STAPSDT_TYPE || | |
1011 | strncmp(curr_data_ptr, NOTE_STAPSDT_NAME, name_size) != 0) { | |
1012 | continue; | |
1013 | } | |
1014 | ||
1015 | curr_data_ptr += name_size; | |
1016 | ||
8bd52288 FD |
1017 | /* Get probe location. */ |
1018 | curr_probe_location = *(uint64_t *) curr_data_ptr; | |
1019 | curr_data_ptr += sizeof(uint64_t); | |
1020 | ||
1021 | /* Pass over the base. Not needed. */ | |
1022 | curr_data_ptr += sizeof(uint64_t); | |
1023 | ||
1024 | /* Get semaphore location. */ | |
1025 | curr_semaphore_location = *(uint64_t *) curr_data_ptr; | |
1026 | curr_data_ptr += sizeof(uint64_t); | |
1027 | /* Get provider name. */ | |
1028 | curr_provider = curr_data_ptr; | |
1029 | curr_data_ptr += strlen(curr_provider) + 1; | |
1030 | ||
1031 | /* Get probe name. */ | |
1032 | curr_probe = curr_data_ptr; | |
8bd52288 FD |
1033 | |
1034 | /* Check if the provider and probe name match */ | |
1035 | if (strcmp(provider_name, curr_provider) == 0 && | |
1036 | strcmp(probe_name, curr_probe) == 0) { | |
1037 | int new_size; | |
1038 | ||
1039 | /* | |
1040 | * We currently don't support SDT probes with semaphores. Return | |
1041 | * success as we found a matching probe but it's guarded by a | |
1042 | * semaphore. | |
1043 | */ | |
1044 | if (curr_semaphore_location != 0) { | |
1045 | ret = LTTNG_ERR_SDT_PROBE_SEMAPHORE; | |
09f3038c | 1046 | goto realloc_error; |
8bd52288 FD |
1047 | } |
1048 | ||
1049 | new_size = (++nb_match) * sizeof(uint64_t); | |
1050 | ||
1051 | /* | |
1052 | * Found a match with not semaphore, we need to copy the | |
1053 | * probe_location to the output parameter. | |
1054 | */ | |
a6bc4ca9 | 1055 | new_probe_locs = (uint64_t *) realloc(probe_locs, new_size); |
8bd52288 FD |
1056 | if (!new_probe_locs) { |
1057 | /* Error allocating a larger buffer */ | |
1058 | DBG("Allocation error in SDT."); | |
1059 | ret = LTTNG_ERR_NOMEM; | |
1060 | goto realloc_error; | |
1061 | } | |
1062 | probe_locs = new_probe_locs; | |
1063 | new_probe_locs = NULL; | |
1064 | ||
1065 | /* | |
1066 | * Use the virtual address of the probe to compute the offset of | |
1067 | * this probe from the beginning of the executable file. | |
1068 | */ | |
1069 | ret = lttng_elf_convert_addr_in_text_to_offset(elf, | |
1070 | curr_probe_location, &curr_probe_offset); | |
1071 | if (ret) { | |
1072 | DBG("Conversion error in SDT."); | |
1073 | goto realloc_error; | |
1074 | } | |
1075 | ||
1076 | probe_locs[nb_match - 1] = curr_probe_offset; | |
1077 | } | |
1078 | } | |
1079 | ||
1080 | end: | |
1081 | free(stap_note_section_data); | |
1082 | destroy_elf_error: | |
1083 | lttng_elf_destroy(elf); | |
1084 | error: | |
1085 | return ret; | |
1086 | realloc_error: | |
1087 | free(probe_locs); | |
1088 | goto end; | |
1089 | } |