ltrace-elf.c revision 7287166e8fd5949ffcf8eb1f3d378b5ea538915e
1/* 2 * This file is part of ltrace. 3 * Copyright (C) 2006,2010,2011,2012,2013 Petr Machata, Red Hat Inc. 4 * Copyright (C) 2010 Zachary T Welch, CodeSourcery 5 * Copyright (C) 2010 Joe Damato 6 * Copyright (C) 1997,1998,2001,2004,2007,2008,2009 Juan Cespedes 7 * Copyright (C) 2006 Olaf Hering, SUSE Linux GmbH 8 * Copyright (C) 2006 Eric Vaitl, Cisco Systems, Inc. 9 * Copyright (C) 2006 Paul Gilliam, IBM Corporation 10 * Copyright (C) 2006 Ian Wienand 11 * 12 * This program is free software; you can redistribute it and/or 13 * modify it under the terms of the GNU General Public License as 14 * published by the Free Software Foundation; either version 2 of the 15 * License, or (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, but 18 * WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 20 * General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 25 * 02110-1301 USA 26 */ 27 28#include "config.h" 29 30#include <assert.h> 31#ifdef __linux__ 32#include <endian.h> 33#endif 34#include <errno.h> 35#include <fcntl.h> 36#include <gelf.h> 37#include <inttypes.h> 38#include <search.h> 39#include <stdint.h> 40#include <stdio.h> 41#include <stdlib.h> 42#include <string.h> 43#include <strings.h> 44#include <unistd.h> 45 46#include "backend.h" 47#include "filter.h" 48#include "library.h" 49#include "ltrace-elf.h" 50#include "proc.h" 51#include "debug.h" 52#include "options.h" 53 54#ifndef ARCH_HAVE_LTELF_DATA 55int 56arch_elf_init(struct ltelf *lte, struct library *lib) 57{ 58 return 0; 59} 60 61void 62arch_elf_destroy(struct ltelf *lte) 63{ 64} 65#endif 66 67int 68default_elf_add_plt_entry(struct process *proc, struct ltelf *lte, 69 const char *a_name, GElf_Rela *rela, size_t ndx, 70 struct library_symbol **ret) 71{ 72 char *name = strdup(a_name); 73 if (name == NULL) { 74 fail_message: 75 fprintf(stderr, "Couldn't create symbol for PLT entry: %s\n", 76 strerror(errno)); 77 fail: 78 free(name); 79 return -1; 80 } 81 82 GElf_Addr addr = arch_plt_sym_val(lte, ndx, rela); 83 84 struct library_symbol *libsym = malloc(sizeof(*libsym)); 85 if (libsym == NULL) 86 goto fail_message; 87 88 /* XXX The double cast should be removed when 89 * arch_addr_t becomes integral type. */ 90 arch_addr_t taddr = (arch_addr_t) 91 (uintptr_t)(addr + lte->bias); 92 93 if (library_symbol_init(libsym, taddr, name, 1, LS_TOPLT_EXEC) < 0) { 94 free(libsym); 95 goto fail; 96 } 97 98 libsym->next = *ret; 99 *ret = libsym; 100 return 0; 101} 102 103#ifndef ARCH_HAVE_ADD_PLT_ENTRY 104enum plt_status 105arch_elf_add_plt_entry(struct process *proc, struct ltelf *lte, 106 const char *a_name, GElf_Rela *rela, size_t ndx, 107 struct library_symbol **ret) 108{ 109 return PLT_DEFAULT; 110} 111#endif 112 113Elf_Data * 114elf_loaddata(Elf_Scn *scn, GElf_Shdr *shdr) 115{ 116 Elf_Data *data = elf_getdata(scn, NULL); 117 if (data == NULL || elf_getdata(scn, data) != NULL 118 || data->d_off || data->d_size != shdr->sh_size) 119 return NULL; 120 return data; 121} 122 123static int 124elf_get_section_if(struct ltelf *lte, Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr, 125 int (*predicate)(Elf_Scn *, GElf_Shdr *, void *data), 126 void *data) 127{ 128 int i; 129 for (i = 1; i < lte->ehdr.e_shnum; ++i) { 130 Elf_Scn *scn; 131 GElf_Shdr shdr; 132 133 scn = elf_getscn(lte->elf, i); 134 if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) { 135 debug(1, "Couldn't read section or header."); 136 return -1; 137 } 138 if (predicate(scn, &shdr, data)) { 139 *tgt_sec = scn; 140 *tgt_shdr = shdr; 141 return 0; 142 } 143 } 144 145 *tgt_sec = NULL; 146 return 0; 147} 148 149static int 150inside_p(Elf_Scn *scn, GElf_Shdr *shdr, void *data) 151{ 152 GElf_Addr addr = *(GElf_Addr *)data; 153 return addr >= shdr->sh_addr 154 && addr < shdr->sh_addr + shdr->sh_size; 155} 156 157int 158elf_get_section_covering(struct ltelf *lte, GElf_Addr addr, 159 Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr) 160{ 161 return elf_get_section_if(lte, tgt_sec, tgt_shdr, 162 &inside_p, &addr); 163} 164 165static int 166type_p(Elf_Scn *scn, GElf_Shdr *shdr, void *data) 167{ 168 GElf_Word type = *(GElf_Word *)data; 169 return shdr->sh_type == type; 170} 171 172int 173elf_get_section_type(struct ltelf *lte, GElf_Word type, 174 Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr) 175{ 176 return elf_get_section_if(lte, tgt_sec, tgt_shdr, 177 &type_p, &type); 178} 179 180struct section_named_data { 181 struct ltelf *lte; 182 const char *name; 183}; 184 185static int 186name_p(Elf_Scn *scn, GElf_Shdr *shdr, void *d) 187{ 188 struct section_named_data *data = d; 189 const char *name = elf_strptr(data->lte->elf, 190 data->lte->ehdr.e_shstrndx, 191 shdr->sh_name); 192 return strcmp(name, data->name) == 0; 193} 194 195int 196elf_get_section_named(struct ltelf *lte, const char *name, 197 Elf_Scn **tgt_sec, GElf_Shdr *tgt_shdr) 198{ 199 struct section_named_data data = { 200 .lte = lte, 201 .name = name, 202 }; 203 return elf_get_section_if(lte, tgt_sec, tgt_shdr, 204 &name_p, &data); 205} 206 207int 208elf_can_read_next(Elf_Data *data, GElf_Xword offset, GElf_Xword size) 209{ 210 assert(data != NULL); 211 if (data->d_size < size || offset > data->d_size - size) { 212 debug(1, "Not enough data to read %"PRId64"-byte value" 213 " at offset %"PRId64".", size, offset); 214 return 0; 215 } 216 return 1; 217} 218 219#define DEF_READER(NAME, SIZE) \ 220 int \ 221 NAME(Elf_Data *data, GElf_Xword offset, uint##SIZE##_t *retp) \ 222 { \ 223 if (!elf_can_read_next(data, offset, SIZE / 8)) \ 224 return -1; \ 225 \ 226 if (data->d_buf == NULL) /* NODATA section */ { \ 227 *retp = 0; \ 228 return 0; \ 229 } \ 230 \ 231 union { \ 232 uint##SIZE##_t dst; \ 233 char buf[0]; \ 234 } u; \ 235 memcpy(u.buf, data->d_buf + offset, sizeof(u.dst)); \ 236 *retp = u.dst; \ 237 return 0; \ 238 } 239 240DEF_READER(elf_read_u8, 8) 241DEF_READER(elf_read_u16, 16) 242DEF_READER(elf_read_u32, 32) 243DEF_READER(elf_read_u64, 64) 244 245#undef DEF_READER 246 247#define DEF_READER(NAME, SIZE) \ 248 int \ 249 NAME(Elf_Data *data, GElf_Xword *offset, uint##SIZE##_t *retp) \ 250 { \ 251 int rc = elf_read_u##SIZE(data, *offset, retp); \ 252 if (rc < 0) \ 253 return rc; \ 254 *offset += SIZE / 8; \ 255 return 0; \ 256 } 257 258DEF_READER(elf_read_next_u8, 8) 259DEF_READER(elf_read_next_u16, 16) 260DEF_READER(elf_read_next_u32, 32) 261DEF_READER(elf_read_next_u64, 64) 262 263#undef DEF_READER 264 265int 266elf_read_next_uleb128(Elf_Data *data, GElf_Xword *offset, uint64_t *retp) 267{ 268 uint64_t result = 0; 269 int shift = 0; 270 int size = 8 * sizeof result; 271 272 while (1) { 273 uint8_t byte; 274 if (elf_read_next_u8(data, offset, &byte) < 0) 275 return -1; 276 277 uint8_t payload = byte & 0x7f; 278 result |= (uint64_t)payload << shift; 279 shift += 7; 280 if (shift > size && byte != 0x1) 281 return -1; 282 if ((byte & 0x80) == 0) 283 break; 284 } 285 286 if (retp != NULL) 287 *retp = result; 288 return 0; 289} 290 291int 292elf_read_uleb128(Elf_Data *data, GElf_Xword offset, uint64_t *retp) 293{ 294 return elf_read_next_uleb128(data, &offset, retp); 295} 296 297int 298open_elf(struct ltelf *lte, const char *filename) 299{ 300 lte->fd = open(filename, O_RDONLY); 301 if (lte->fd == -1) 302 return 1; 303 304 elf_version(EV_CURRENT); 305 306#ifdef HAVE_ELF_C_READ_MMAP 307 lte->elf = elf_begin(lte->fd, ELF_C_READ_MMAP, NULL); 308#else 309 lte->elf = elf_begin(lte->fd, ELF_C_READ, NULL); 310#endif 311 312 if (lte->elf == NULL || elf_kind(lte->elf) != ELF_K_ELF) { 313 fprintf(stderr, "\"%s\" is not an ELF file\n", filename); 314 exit(EXIT_FAILURE); 315 } 316 317 if (gelf_getehdr(lte->elf, <e->ehdr) == NULL) { 318 fprintf(stderr, "can't read ELF header of \"%s\": %s\n", 319 filename, elf_errmsg(-1)); 320 exit(EXIT_FAILURE); 321 } 322 323 if (lte->ehdr.e_type != ET_EXEC && lte->ehdr.e_type != ET_DYN) { 324 fprintf(stderr, "\"%s\" is neither an ELF executable" 325 " nor a shared library\n", filename); 326 exit(EXIT_FAILURE); 327 } 328 329 if (1 330#ifdef LT_ELF_MACHINE 331 && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS 332 || lte->ehdr.e_machine != LT_ELF_MACHINE) 333#endif 334#ifdef LT_ELF_MACHINE2 335 && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS2 336 || lte->ehdr.e_machine != LT_ELF_MACHINE2) 337#endif 338#ifdef LT_ELF_MACHINE3 339 && (lte->ehdr.e_ident[EI_CLASS] != LT_ELFCLASS3 340 || lte->ehdr.e_machine != LT_ELF_MACHINE3) 341#endif 342 ) { 343 fprintf(stderr, 344 "\"%s\" is ELF from incompatible architecture\n", 345 filename); 346 exit(EXIT_FAILURE); 347 } 348 349 return 0; 350} 351 352static void 353read_symbol_table(struct ltelf *lte, const char *filename, 354 Elf_Scn *scn, GElf_Shdr *shdr, const char *name, 355 Elf_Data **datap, size_t *countp, const char **strsp) 356{ 357 *datap = elf_getdata(scn, NULL); 358 *countp = shdr->sh_size / shdr->sh_entsize; 359 if ((*datap == NULL || elf_getdata(scn, *datap) != NULL) 360 && options.static_filter != NULL) { 361 fprintf(stderr, "Couldn't get data of section" 362 " %s from \"%s\": %s\n", 363 name, filename, elf_errmsg(-1)); 364 exit(EXIT_FAILURE); 365 } 366 367 scn = elf_getscn(lte->elf, shdr->sh_link); 368 GElf_Shdr shdr2; 369 if (scn == NULL || gelf_getshdr(scn, &shdr2) == NULL) { 370 fprintf(stderr, "Couldn't get header of section" 371 " #%d from \"%s\": %s\n", 372 shdr->sh_link, filename, elf_errmsg(-1)); 373 exit(EXIT_FAILURE); 374 } 375 376 Elf_Data *data = elf_getdata(scn, NULL); 377 if (data == NULL || elf_getdata(scn, data) != NULL 378 || shdr2.sh_size != data->d_size || data->d_off) { 379 fprintf(stderr, "Couldn't get data of section" 380 " #%d from \"%s\": %s\n", 381 shdr2.sh_link, filename, elf_errmsg(-1)); 382 exit(EXIT_FAILURE); 383 } 384 385 *strsp = data->d_buf; 386} 387 388static int 389do_init_elf(struct ltelf *lte, const char *filename) 390{ 391 int i; 392 GElf_Addr relplt_addr = 0; 393 GElf_Addr soname_offset = 0; 394 395 debug(DEBUG_FUNCTION, "do_init_elf(filename=%s)", filename); 396 debug(1, "Reading ELF from %s...", filename); 397 398 for (i = 1; i < lte->ehdr.e_shnum; ++i) { 399 Elf_Scn *scn; 400 GElf_Shdr shdr; 401 const char *name; 402 403 scn = elf_getscn(lte->elf, i); 404 if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) { 405 fprintf(stderr, "Couldn't get section #%d from" 406 " \"%s\": %s\n", i, filename, elf_errmsg(-1)); 407 exit(EXIT_FAILURE); 408 } 409 410 name = elf_strptr(lte->elf, lte->ehdr.e_shstrndx, shdr.sh_name); 411 if (name == NULL) { 412 fprintf(stderr, "Couldn't get name of section #%d from" 413 " \"%s\": %s\n", i, filename, elf_errmsg(-1)); 414 exit(EXIT_FAILURE); 415 } 416 417 if (shdr.sh_type == SHT_SYMTAB) { 418 read_symbol_table(lte, filename, 419 scn, &shdr, name, <e->symtab, 420 <e->symtab_count, <e->strtab); 421 422 } else if (shdr.sh_type == SHT_DYNSYM) { 423 read_symbol_table(lte, filename, 424 scn, &shdr, name, <e->dynsym, 425 <e->dynsym_count, <e->dynstr); 426 427 } else if (shdr.sh_type == SHT_DYNAMIC) { 428 Elf_Data *data; 429 size_t j; 430 431 lte->dyn_addr = shdr.sh_addr + lte->bias; 432 lte->dyn_sz = shdr.sh_size; 433 434 data = elf_getdata(scn, NULL); 435 if (data == NULL || elf_getdata(scn, data) != NULL) { 436 fprintf(stderr, "Couldn't get .dynamic data" 437 " from \"%s\": %s\n", 438 filename, strerror(errno)); 439 exit(EXIT_FAILURE); 440 } 441 442 for (j = 0; j < shdr.sh_size / shdr.sh_entsize; ++j) { 443 GElf_Dyn dyn; 444 445 if (gelf_getdyn(data, j, &dyn) == NULL) { 446 fprintf(stderr, "Couldn't get .dynamic" 447 " data from \"%s\": %s\n", 448 filename, strerror(errno)); 449 exit(EXIT_FAILURE); 450 } 451 if (dyn.d_tag == DT_JMPREL) 452 relplt_addr = dyn.d_un.d_ptr; 453 else if (dyn.d_tag == DT_PLTRELSZ) 454 lte->relplt_size = dyn.d_un.d_val; 455 else if (dyn.d_tag == DT_SONAME) 456 soname_offset = dyn.d_un.d_val; 457 } 458 } else if (shdr.sh_type == SHT_PROGBITS 459 || shdr.sh_type == SHT_NOBITS) { 460 if (strcmp(name, ".plt") == 0) { 461 lte->plt_addr = shdr.sh_addr; 462 lte->plt_size = shdr.sh_size; 463 lte->plt_data = elf_loaddata(scn, &shdr); 464 if (lte->plt_data == NULL) 465 fprintf(stderr, 466 "Can't load .plt data\n"); 467 lte->plt_flags = shdr.sh_flags; 468 } 469#ifdef ARCH_SUPPORTS_OPD 470 else if (strcmp(name, ".opd") == 0) { 471 lte->opd_addr = (GElf_Addr *) (long) shdr.sh_addr; 472 lte->opd_size = shdr.sh_size; 473 lte->opd = elf_rawdata(scn, NULL); 474 } 475#endif 476 } 477 } 478 479 if (lte->dynsym == NULL || lte->dynstr == NULL) { 480 fprintf(stderr, "Couldn't find .dynsym or .dynstr in \"%s\"\n", 481 filename); 482 exit(EXIT_FAILURE); 483 } 484 485 if (!relplt_addr || !lte->plt_addr) { 486 debug(1, "%s has no PLT relocations", filename); 487 lte->relplt = NULL; 488 lte->relplt_count = 0; 489 } else if (lte->relplt_size == 0) { 490 debug(1, "%s has unknown PLT size", filename); 491 lte->relplt = NULL; 492 lte->relplt_count = 0; 493 } else { 494 495 for (i = 1; i < lte->ehdr.e_shnum; ++i) { 496 Elf_Scn *scn; 497 GElf_Shdr shdr; 498 499 scn = elf_getscn(lte->elf, i); 500 if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) { 501 fprintf(stderr, "Couldn't get section header" 502 " from \"%s\": %s\n", 503 filename, elf_errmsg(-1)); 504 exit(EXIT_FAILURE); 505 } 506 if (shdr.sh_addr == relplt_addr 507 && shdr.sh_size == lte->relplt_size) { 508 lte->relplt = elf_getdata(scn, NULL); 509 lte->relplt_count = 510 shdr.sh_size / shdr.sh_entsize; 511 if (lte->relplt == NULL 512 || elf_getdata(scn, lte->relplt) != NULL) { 513 fprintf(stderr, "Couldn't get .rel*.plt" 514 " data from \"%s\": %s\n", 515 filename, elf_errmsg(-1)); 516 exit(EXIT_FAILURE); 517 } 518 break; 519 } 520 } 521 522 if (i == lte->ehdr.e_shnum) { 523 fprintf(stderr, 524 "Couldn't find .rel*.plt section in \"%s\"\n", 525 filename); 526 exit(EXIT_FAILURE); 527 } 528 529 debug(1, "%s %zd PLT relocations", filename, lte->relplt_count); 530 } 531 532 if (soname_offset != 0) 533 lte->soname = lte->dynstr + soname_offset; 534 535 return 0; 536} 537 538void 539do_close_elf(struct ltelf *lte) 540{ 541 debug(DEBUG_FUNCTION, "do_close_elf()"); 542 arch_elf_destroy(lte); 543 elf_end(lte->elf); 544 close(lte->fd); 545} 546 547int 548elf_get_sym_info(struct ltelf *lte, const char *filename, 549 size_t sym_index, GElf_Rela *rela, GElf_Sym *sym) 550{ 551 int i = sym_index; 552 GElf_Rel rel; 553 void *ret; 554 555 if (lte->relplt->d_type == ELF_T_REL) { 556 ret = gelf_getrel(lte->relplt, i, &rel); 557 rela->r_offset = rel.r_offset; 558 rela->r_info = rel.r_info; 559 rela->r_addend = 0; 560 } else { 561 ret = gelf_getrela(lte->relplt, i, rela); 562 } 563 564 if (ret == NULL 565 || ELF64_R_SYM(rela->r_info) >= lte->dynsym_count 566 || gelf_getsym(lte->dynsym, ELF64_R_SYM(rela->r_info), 567 sym) == NULL) { 568 fprintf(stderr, 569 "Couldn't get relocation from \"%s\": %s\n", 570 filename, elf_errmsg(-1)); 571 exit(EXIT_FAILURE); 572 } 573 574 return 0; 575} 576 577#ifndef ARCH_HAVE_GET_SYMINFO 578int 579arch_get_sym_info(struct ltelf *lte, const char *filename, 580 size_t sym_index, GElf_Rela *rela, GElf_Sym *sym) 581{ 582 return elf_get_sym_info(lte, filename, sym_index, rela, sym); 583} 584#endif 585 586static void 587mark_chain_latent(struct library_symbol *libsym) 588{ 589 for (; libsym != NULL; libsym = libsym->next) { 590 debug(DEBUG_FUNCTION, "marking %s latent", libsym->name); 591 libsym->latent = 1; 592 } 593} 594 595static int 596populate_plt(struct process *proc, const char *filename, 597 struct ltelf *lte, struct library *lib, 598 int latent_plts) 599{ 600 size_t i; 601 for (i = 0; i < lte->relplt_count; ++i) { 602 GElf_Rela rela; 603 GElf_Sym sym; 604 605 if (arch_get_sym_info(lte, filename, i, &rela, &sym) < 0) 606 continue; /* Skip this entry. */ 607 608 char const *name = lte->dynstr + sym.st_name; 609 610 /* If the symbol wasn't matched, reject it, unless we 611 * need to keep latent PLT breakpoints for tracing 612 * exports. */ 613 int matched = filter_matches_symbol(options.plt_filter, 614 name, lib); 615 if (!matched && !latent_plts) 616 continue; 617 618 struct library_symbol *libsym = NULL; 619 switch (arch_elf_add_plt_entry(proc, lte, name, 620 &rela, i, &libsym)) { 621 case PLT_DEFAULT: 622 if (default_elf_add_plt_entry(proc, lte, name, 623 &rela, i, &libsym) < 0) 624 /* fall-through */ 625 case PLT_FAIL: 626 return -1; 627 /* fall-through */ 628 case PLT_OK: 629 if (libsym != NULL) { 630 /* If we are adding those symbols just 631 * for tracing exports, mark them all 632 * latent. */ 633 if (!matched) 634 mark_chain_latent(libsym); 635 library_add_symbol(lib, libsym); 636 } 637 } 638 } 639 return 0; 640} 641 642/* When -x rules result in request to trace several aliases, we only 643 * want to add such symbol once. The only way that those symbols 644 * differ in is their name, e.g. in glibc you have __GI___libc_free, 645 * __cfree, __free, __libc_free, cfree and free all defined on the 646 * same address. So instead we keep this unique symbol struct for 647 * each address, and replace name in libsym with a shorter variant if 648 * we find it. */ 649struct unique_symbol { 650 arch_addr_t addr; 651 struct library_symbol *libsym; 652}; 653 654static int 655unique_symbol_cmp(const void *key, const void *val) 656{ 657 const struct unique_symbol *sym_key = key; 658 const struct unique_symbol *sym_val = val; 659 return sym_key->addr != sym_val->addr; 660} 661 662static enum callback_status 663symbol_with_address(struct library_symbol *sym, void *addrptr) 664{ 665 return sym->enter_addr == *(arch_addr_t *)addrptr 666 ? CBS_STOP : CBS_CONT; 667} 668 669static int 670populate_this_symtab(struct process *proc, const char *filename, 671 struct ltelf *lte, struct library *lib, 672 Elf_Data *symtab, const char *strtab, size_t size, 673 struct library_exported_name **names) 674{ 675 /* If a valid NAMES is passed, we pass in *NAMES a list of 676 * symbol names that this library exports. */ 677 if (names != NULL) 678 *names = NULL; 679 680 /* Using sorted array would be arguably better, but this 681 * should be well enough for the number of symbols that we 682 * typically deal with. */ 683 size_t num_symbols = 0; 684 struct unique_symbol *symbols = malloc(sizeof(*symbols) * size); 685 if (symbols == NULL) { 686 fprintf(stderr, "couldn't insert symbols for -x: %s\n", 687 strerror(errno)); 688 return -1; 689 } 690 691 GElf_Word secflags[lte->ehdr.e_shnum]; 692 size_t i; 693 for (i = 1; i < lte->ehdr.e_shnum; ++i) { 694 Elf_Scn *scn = elf_getscn(lte->elf, i); 695 GElf_Shdr shdr; 696 if (scn == NULL || gelf_getshdr(scn, &shdr) == NULL) 697 secflags[i] = 0; 698 else 699 secflags[i] = shdr.sh_flags; 700 } 701 702 for (i = 0; i < size; ++i) { 703 GElf_Sym sym; 704 if (gelf_getsym(symtab, i, &sym) == NULL) { 705 fail: 706 fprintf(stderr, 707 "couldn't get symbol #%zd from %s: %s\n", 708 i, filename, elf_errmsg(-1)); 709 continue; 710 } 711 712 /* XXX support IFUNC as well. */ 713 if (GELF_ST_TYPE(sym.st_info) != STT_FUNC 714 || sym.st_value == 0 715 || sym.st_shndx == STN_UNDEF) 716 continue; 717 718 /* Find symbol name and snip version. */ 719 const char *orig_name = strtab + sym.st_name; 720 const char *version = strchr(orig_name, '@'); 721 size_t len = version != NULL ? (assert(version > orig_name), 722 (size_t)(version - orig_name)) 723 : strlen(orig_name); 724 char name[len + 1]; 725 memcpy(name, orig_name, len); 726 name[len] = 0; 727 728 /* If we are interested in exports, store this name. */ 729 char *name_copy = NULL; 730 if (names != NULL) { 731 struct library_exported_name *export = NULL; 732 name_copy = strdup(name); 733 734 if (name_copy == NULL 735 || (export = malloc(sizeof(*export))) == NULL) { 736 free(name_copy); 737 fprintf(stderr, "Couldn't store symbol %s. " 738 "Tracing may be incomplete.\n", name); 739 } else { 740 export->name = name_copy; 741 export->own_name = 1; 742 export->next = *names; 743 *names = export; 744 } 745 } 746 747 /* If the symbol is not matched, skip it. We already 748 * stored it to export list above. */ 749 if (!filter_matches_symbol(options.static_filter, name, lib)) 750 continue; 751 752 arch_addr_t addr = (arch_addr_t) 753 (uintptr_t)(sym.st_value + lte->bias); 754 arch_addr_t naddr; 755 756 /* On arches that support OPD, the value of typical 757 * function symbol will be a pointer to .opd, but some 758 * will point directly to .text. We don't want to 759 * translate those. */ 760 if (secflags[sym.st_shndx] & SHF_EXECINSTR) { 761 naddr = addr; 762 } else if (arch_translate_address(lte, addr, &naddr) < 0) { 763 fprintf(stderr, 764 "couldn't translate address of %s@%s: %s\n", 765 name, lib->soname, strerror(errno)); 766 continue; 767 } 768 769 char *full_name; 770 int own_full_name = 1; 771 if (name_copy == NULL) { 772 full_name = strdup(name); 773 if (full_name == NULL) 774 goto fail; 775 } else { 776 full_name = name_copy; 777 own_full_name = 0; 778 } 779 780 /* Look whether we already have a symbol for this 781 * address. If not, add this one. */ 782 struct unique_symbol key = { naddr, NULL }; 783 struct unique_symbol *unique 784 = lsearch(&key, symbols, &num_symbols, 785 sizeof(*symbols), &unique_symbol_cmp); 786 787 if (unique->libsym == NULL) { 788 struct library_symbol *libsym = malloc(sizeof(*libsym)); 789 if (libsym == NULL 790 || library_symbol_init(libsym, naddr, 791 full_name, own_full_name, 792 LS_TOPLT_NONE) < 0) { 793 --num_symbols; 794 goto fail; 795 } 796 unique->libsym = libsym; 797 unique->addr = naddr; 798 799 } else if (strlen(full_name) < strlen(unique->libsym->name)) { 800 library_symbol_set_name(unique->libsym, 801 full_name, own_full_name); 802 803 } else if (own_full_name) { 804 free(full_name); 805 } 806 } 807 808 /* Now we do the union of this set of unique symbols with 809 * what's already in the library. */ 810 for (i = 0; i < num_symbols; ++i) { 811 struct library_symbol *this_sym = symbols[i].libsym; 812 assert(this_sym != NULL); 813 struct library_symbol *other 814 = library_each_symbol(lib, NULL, symbol_with_address, 815 &this_sym->enter_addr); 816 if (other != NULL) { 817 library_symbol_destroy(this_sym); 818 free(this_sym); 819 symbols[i].libsym = NULL; 820 } 821 } 822 823 for (i = 0; i < num_symbols; ++i) 824 if (symbols[i].libsym != NULL) 825 library_add_symbol(lib, symbols[i].libsym); 826 827 free(symbols); 828 return 0; 829} 830 831static int 832populate_symtab(struct process *proc, const char *filename, 833 struct ltelf *lte, struct library *lib, 834 int symtabs, int exports) 835{ 836 int status; 837 if (symtabs && lte->symtab != NULL && lte->strtab != NULL 838 && (status = populate_this_symtab(proc, filename, lte, lib, 839 lte->symtab, lte->strtab, 840 lte->symtab_count, NULL)) < 0) 841 return status; 842 843 /* Check whether we want to trace symbols implemented by this 844 * library (-l). */ 845 struct library_exported_name **names = NULL; 846 if (exports) { 847 debug(DEBUG_FUNCTION, "-l matches %s", lib->soname); 848 names = &lib->exported_names; 849 } 850 851 return populate_this_symtab(proc, filename, lte, lib, 852 lte->dynsym, lte->dynstr, 853 lte->dynsym_count, names); 854} 855 856static int 857read_module(struct library *lib, struct process *proc, 858 const char *filename, GElf_Addr bias, int main) 859{ 860 struct ltelf lte = {}; 861 if (open_elf(<e, filename) < 0) 862 return -1; 863 864 /* XXX When we abstract ABI into a module, this should instead 865 * become something like 866 * 867 * proc->abi = arch_get_abi(lte.ehdr); 868 * 869 * The code in open_elf needs to be replaced by this logic. 870 * Be warned that libltrace.c calls open_elf as well to 871 * determine whether ABI is supported. This is to get 872 * reasonable error messages when trying to run 64-bit binary 873 * with 32-bit ltrace. It is desirable to preserve this. */ 874 proc->e_machine = lte.ehdr.e_machine; 875 proc->e_class = lte.ehdr.e_ident[EI_CLASS]; 876 get_arch_dep(proc); 877 878 /* Find out the base address. For PIE main binaries we look 879 * into auxv, otherwise we scan phdrs. */ 880 if (main && lte.ehdr.e_type == ET_DYN) { 881 arch_addr_t entry; 882 if (process_get_entry(proc, &entry, NULL) < 0) { 883 fprintf(stderr, "Couldn't find entry of PIE %s\n", 884 filename); 885 return -1; 886 } 887 /* XXX The double cast should be removed when 888 * arch_addr_t becomes integral type. */ 889 lte.entry_addr = (GElf_Addr)(uintptr_t)entry; 890 lte.bias = (GElf_Addr)(uintptr_t)entry - lte.ehdr.e_entry; 891 892 } else { 893 GElf_Phdr phdr; 894 size_t i; 895 for (i = 0; gelf_getphdr (lte.elf, i, &phdr) != NULL; ++i) { 896 if (phdr.p_type == PT_LOAD) { 897 lte.base_addr = phdr.p_vaddr + bias; 898 break; 899 } 900 } 901 902 lte.bias = bias; 903 lte.entry_addr = lte.ehdr.e_entry + lte.bias; 904 905 if (lte.base_addr == 0) { 906 fprintf(stderr, 907 "Couldn't determine base address of %s\n", 908 filename); 909 return -1; 910 } 911 } 912 913 if (do_init_elf(<e, filename) < 0) 914 return -1; 915 916 if (arch_elf_init(<e, lib) < 0) { 917 fprintf(stderr, "Backend initialization failed.\n"); 918 return -1; 919 } 920 921 int status = 0; 922 if (lib == NULL) 923 goto fail; 924 925 /* Note that we set soname and pathname as soon as they are 926 * allocated, so in case of further errors, this get released 927 * when LIB is released, which should happen in the caller 928 * when we return error. */ 929 930 if (lib->pathname == NULL) { 931 char *pathname = strdup(filename); 932 if (pathname == NULL) 933 goto fail; 934 library_set_pathname(lib, pathname, 1); 935 } 936 937 if (lte.soname != NULL) { 938 char *soname = strdup(lte.soname); 939 if (soname == NULL) 940 goto fail; 941 library_set_soname(lib, soname, 1); 942 } else { 943 const char *soname = rindex(lib->pathname, '/'); 944 if (soname != NULL) 945 soname += 1; 946 else 947 soname = lib->pathname; 948 library_set_soname(lib, soname, 0); 949 } 950 951 /* XXX The double cast should be removed when 952 * arch_addr_t becomes integral type. */ 953 arch_addr_t entry = (arch_addr_t)(uintptr_t)lte.entry_addr; 954 if (arch_translate_address(<e, entry, &entry) < 0) 955 goto fail; 956 957 /* XXX The double cast should be removed when 958 * arch_addr_t becomes integral type. */ 959 lib->base = (arch_addr_t)(uintptr_t)lte.base_addr; 960 lib->entry = entry; 961 /* XXX The double cast should be removed when 962 * arch_addr_t becomes integral type. */ 963 lib->dyn_addr = (arch_addr_t)(uintptr_t)lte.dyn_addr; 964 965 /* There are two reasons that we need to inspect symbol tables 966 * or populate PLT entries. Either the user requested 967 * corresponding tracing features (respectively -x and -e), or 968 * they requested tracing exported symbols (-l). 969 * 970 * In the latter case we need to keep even those PLT slots 971 * that are not requested by -e (but we keep them latent). We 972 * also need to inspect .dynsym to find what exports this 973 * library provide, to turn on existing latent PLT 974 * entries. */ 975 976 int plts = filter_matches_library(options.plt_filter, lib); 977 if ((plts || options.export_filter != NULL) 978 && populate_plt(proc, filename, <e, lib, 979 options.export_filter != NULL) < 0) 980 goto fail; 981 982 int exports = filter_matches_library(options.export_filter, lib); 983 int symtabs = filter_matches_library(options.static_filter, lib); 984 if ((symtabs || exports) 985 && populate_symtab(proc, filename, <e, lib, 986 symtabs, exports) < 0) 987 goto fail; 988 989done: 990 do_close_elf(<e); 991 return status; 992 993fail: 994 status = -1; 995 goto done; 996} 997 998int 999ltelf_read_library(struct library *lib, struct process *proc, 1000 const char *filename, GElf_Addr bias) 1001{ 1002 return read_module(lib, proc, filename, bias, 0); 1003} 1004 1005 1006struct library * 1007ltelf_read_main_binary(struct process *proc, const char *path) 1008{ 1009 struct library *lib = malloc(sizeof(*lib)); 1010 if (lib == NULL || library_init(lib, LT_LIBTYPE_MAIN) < 0) { 1011 free(lib); 1012 return NULL; 1013 } 1014 library_set_pathname(lib, path, 0); 1015 1016 /* There is a race between running the process and reading its 1017 * binary for internal consumption. So open the binary from 1018 * the /proc filesystem. XXX Note that there is similar race 1019 * for libraries, but there we don't have a nice answer like 1020 * that. Presumably we could read the DSOs from the process 1021 * memory image, but that's not currently done. */ 1022 char *fname = pid2name(proc->pid); 1023 if (fname == NULL 1024 || read_module(lib, proc, fname, 0, 1) < 0) { 1025 library_destroy(lib); 1026 free(lib); 1027 lib = NULL; 1028 } 1029 1030 free(fname); 1031 return lib; 1032} 1033