| 1 | /* ELF core file support for BFD. |
| 2 | Copyright (C) 1995-2019 Free Software Foundation, Inc. |
| 3 | |
| 4 | This file is part of BFD, the Binary File Descriptor library. |
| 5 | |
| 6 | This program is free software; you can redistribute it and/or modify |
| 7 | it under the terms of the GNU General Public License as published by |
| 8 | the Free Software Foundation; either version 3 of the License, or |
| 9 | (at your option) any later version. |
| 10 | |
| 11 | This program is distributed in the hope that it will be useful, |
| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 14 | GNU General Public License for more details. |
| 15 | |
| 16 | You should have received a copy of the GNU General Public License |
| 17 | along with this program; if not, write to the Free Software |
| 18 | Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 19 | MA 02110-1301, USA. */ |
| 20 | |
| 21 | char* |
| 22 | elf_core_file_failing_command (bfd *abfd) |
| 23 | { |
| 24 | return elf_tdata (abfd)->core->command; |
| 25 | } |
| 26 | |
| 27 | int |
| 28 | elf_core_file_failing_signal (bfd *abfd) |
| 29 | { |
| 30 | return elf_tdata (abfd)->core->signal; |
| 31 | } |
| 32 | |
| 33 | int |
| 34 | elf_core_file_pid (bfd *abfd) |
| 35 | { |
| 36 | return elf_tdata (abfd)->core->pid; |
| 37 | } |
| 38 | |
| 39 | bfd_boolean |
| 40 | elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd) |
| 41 | { |
| 42 | char* corename; |
| 43 | |
| 44 | /* xvecs must match if both are ELF files for the same target. */ |
| 45 | |
| 46 | if (core_bfd->xvec != exec_bfd->xvec) |
| 47 | { |
| 48 | bfd_set_error (bfd_error_system_call); |
| 49 | return FALSE; |
| 50 | } |
| 51 | |
| 52 | /* If both BFDs have identical build-ids, then they match. */ |
| 53 | if (core_bfd->build_id != NULL |
| 54 | && exec_bfd->build_id != NULL |
| 55 | && core_bfd->build_id->size == exec_bfd->build_id->size |
| 56 | && memcmp (core_bfd->build_id->data, exec_bfd->build_id->data, |
| 57 | core_bfd->build_id->size) == 0) |
| 58 | return TRUE; |
| 59 | |
| 60 | /* See if the name in the corefile matches the executable name. */ |
| 61 | corename = elf_tdata (core_bfd)->core->program; |
| 62 | if (corename != NULL) |
| 63 | { |
| 64 | const char* execname = strrchr (exec_bfd->filename, '/'); |
| 65 | |
| 66 | execname = execname ? execname + 1 : exec_bfd->filename; |
| 67 | |
| 68 | if (strcmp (execname, corename) != 0) |
| 69 | return FALSE; |
| 70 | } |
| 71 | |
| 72 | return TRUE; |
| 73 | } |
| 74 | |
| 75 | /* Core files are simply standard ELF formatted files that partition |
| 76 | the file using the execution view of the file (program header table) |
| 77 | rather than the linking view. In fact, there is no section header |
| 78 | table in a core file. |
| 79 | |
| 80 | The process status information (including the contents of the general |
| 81 | register set) and the floating point register set are stored in a |
| 82 | segment of type PT_NOTE. We handcraft a couple of extra bfd sections |
| 83 | that allow standard bfd access to the general registers (.reg) and the |
| 84 | floating point registers (.reg2). */ |
| 85 | |
| 86 | const bfd_target * |
| 87 | elf_core_file_p (bfd *abfd) |
| 88 | { |
| 89 | Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */ |
| 90 | Elf_Internal_Ehdr *i_ehdrp; /* Elf file header, internal form. */ |
| 91 | Elf_Internal_Phdr *i_phdrp; /* Elf program header, internal form. */ |
| 92 | unsigned int phindex; |
| 93 | const struct elf_backend_data *ebd; |
| 94 | bfd_size_type amt; |
| 95 | |
| 96 | /* Read in the ELF header in external format. */ |
| 97 | if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr)) |
| 98 | { |
| 99 | if (bfd_get_error () != bfd_error_system_call) |
| 100 | goto wrong; |
| 101 | else |
| 102 | goto fail; |
| 103 | } |
| 104 | |
| 105 | /* Check the magic number. */ |
| 106 | if (! elf_file_p (&x_ehdr)) |
| 107 | goto wrong; |
| 108 | |
| 109 | /* FIXME: Check EI_VERSION here ! */ |
| 110 | |
| 111 | /* Check the address size ("class"). */ |
| 112 | if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS) |
| 113 | goto wrong; |
| 114 | |
| 115 | /* Check the byteorder. */ |
| 116 | switch (x_ehdr.e_ident[EI_DATA]) |
| 117 | { |
| 118 | case ELFDATA2MSB: /* Big-endian. */ |
| 119 | if (! bfd_big_endian (abfd)) |
| 120 | goto wrong; |
| 121 | break; |
| 122 | case ELFDATA2LSB: /* Little-endian. */ |
| 123 | if (! bfd_little_endian (abfd)) |
| 124 | goto wrong; |
| 125 | break; |
| 126 | default: |
| 127 | goto wrong; |
| 128 | } |
| 129 | |
| 130 | /* Give abfd an elf_obj_tdata. */ |
| 131 | if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd)) |
| 132 | goto fail; |
| 133 | |
| 134 | /* Swap in the rest of the header, now that we have the byte order. */ |
| 135 | i_ehdrp = elf_elfheader (abfd); |
| 136 | elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp); |
| 137 | |
| 138 | #if DEBUG & 1 |
| 139 | elf_debug_file (i_ehdrp); |
| 140 | #endif |
| 141 | |
| 142 | ebd = get_elf_backend_data (abfd); |
| 143 | |
| 144 | /* Check that the ELF e_machine field matches what this particular |
| 145 | BFD format expects. */ |
| 146 | |
| 147 | if (ebd->elf_machine_code != i_ehdrp->e_machine |
| 148 | && (ebd->elf_machine_alt1 == 0 |
| 149 | || i_ehdrp->e_machine != ebd->elf_machine_alt1) |
| 150 | && (ebd->elf_machine_alt2 == 0 |
| 151 | || i_ehdrp->e_machine != ebd->elf_machine_alt2)) |
| 152 | { |
| 153 | const bfd_target * const *target_ptr; |
| 154 | |
| 155 | if (ebd->elf_machine_code != EM_NONE) |
| 156 | goto wrong; |
| 157 | |
| 158 | /* This is the generic ELF target. Let it match any ELF target |
| 159 | for which we do not have a specific backend. */ |
| 160 | |
| 161 | for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++) |
| 162 | { |
| 163 | const struct elf_backend_data *back; |
| 164 | |
| 165 | if ((*target_ptr)->flavour != bfd_target_elf_flavour) |
| 166 | continue; |
| 167 | back = xvec_get_elf_backend_data (*target_ptr); |
| 168 | if (back->s->arch_size != ARCH_SIZE) |
| 169 | continue; |
| 170 | if (back->elf_machine_code == i_ehdrp->e_machine |
| 171 | || (back->elf_machine_alt1 != 0 |
| 172 | && i_ehdrp->e_machine == back->elf_machine_alt1) |
| 173 | || (back->elf_machine_alt2 != 0 |
| 174 | && i_ehdrp->e_machine == back->elf_machine_alt2)) |
| 175 | { |
| 176 | /* target_ptr is an ELF backend which matches this |
| 177 | object file, so reject the generic ELF target. */ |
| 178 | goto wrong; |
| 179 | } |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | /* If there is no program header, or the type is not a core file, then |
| 184 | we are hosed. */ |
| 185 | if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE) |
| 186 | goto wrong; |
| 187 | |
| 188 | /* Does BFD's idea of the phdr size match the size |
| 189 | recorded in the file? */ |
| 190 | if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr)) |
| 191 | goto wrong; |
| 192 | |
| 193 | /* If the program header count is PN_XNUM(0xffff), the actual |
| 194 | count is in the first section header. */ |
| 195 | if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM) |
| 196 | { |
| 197 | Elf_External_Shdr x_shdr; |
| 198 | Elf_Internal_Shdr i_shdr; |
| 199 | file_ptr where = (file_ptr) i_ehdrp->e_shoff; |
| 200 | |
| 201 | /* Seek to the section header table in the file. */ |
| 202 | if (bfd_seek (abfd, where, SEEK_SET) != 0) |
| 203 | goto fail; |
| 204 | |
| 205 | /* Read the first section header at index 0, and convert to internal |
| 206 | form. */ |
| 207 | if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr)) |
| 208 | goto fail; |
| 209 | elf_swap_shdr_in (abfd, &x_shdr, &i_shdr); |
| 210 | |
| 211 | if (i_shdr.sh_info != 0) |
| 212 | { |
| 213 | i_ehdrp->e_phnum = i_shdr.sh_info; |
| 214 | if (i_ehdrp->e_phnum != i_shdr.sh_info) |
| 215 | goto wrong; |
| 216 | } |
| 217 | } |
| 218 | |
| 219 | /* Sanity check that we can read all of the program headers. |
| 220 | It ought to be good enough to just read the last one. */ |
| 221 | if (i_ehdrp->e_phnum > 1) |
| 222 | { |
| 223 | Elf_External_Phdr x_phdr; |
| 224 | Elf_Internal_Phdr i_phdr; |
| 225 | file_ptr where; |
| 226 | |
| 227 | /* Check that we don't have a totally silly number of |
| 228 | program headers. */ |
| 229 | if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr) |
| 230 | || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr)) |
| 231 | goto wrong; |
| 232 | |
| 233 | where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr)); |
| 234 | if ((bfd_size_type) where <= i_ehdrp->e_phoff) |
| 235 | goto wrong; |
| 236 | |
| 237 | if (bfd_seek (abfd, where, SEEK_SET) != 0) |
| 238 | goto fail; |
| 239 | if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) |
| 240 | goto fail; |
| 241 | } |
| 242 | |
| 243 | /* Move to the start of the program headers. */ |
| 244 | if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0) |
| 245 | goto wrong; |
| 246 | |
| 247 | /* Allocate space for the program headers. */ |
| 248 | amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum; |
| 249 | i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt); |
| 250 | if (!i_phdrp) |
| 251 | goto fail; |
| 252 | |
| 253 | elf_tdata (abfd)->phdr = i_phdrp; |
| 254 | |
| 255 | /* Read and convert to internal form. */ |
| 256 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 257 | { |
| 258 | Elf_External_Phdr x_phdr; |
| 259 | |
| 260 | if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) |
| 261 | goto fail; |
| 262 | |
| 263 | elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex); |
| 264 | } |
| 265 | |
| 266 | /* Set the machine architecture. Do this before processing the |
| 267 | program headers since we need to know the architecture type |
| 268 | when processing the notes of some systems' core files. */ |
| 269 | if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0) |
| 270 | /* It's OK if this fails for the generic target. */ |
| 271 | && ebd->elf_machine_code != EM_NONE) |
| 272 | goto fail; |
| 273 | |
| 274 | /* Let the backend double check the format and override global |
| 275 | information. We do this before processing the program headers |
| 276 | to allow the correct machine (as opposed to just the default |
| 277 | machine) to be set, making it possible for grok_prstatus and |
| 278 | grok_psinfo to rely on the mach setting. */ |
| 279 | if (ebd->elf_backend_object_p != NULL |
| 280 | && ! ebd->elf_backend_object_p (abfd)) |
| 281 | goto wrong; |
| 282 | |
| 283 | /* Process each program header. */ |
| 284 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 285 | if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex)) |
| 286 | goto fail; |
| 287 | |
| 288 | /* Check for core truncation. */ |
| 289 | { |
| 290 | bfd_size_type high = 0; |
| 291 | struct stat statbuf; |
| 292 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 293 | { |
| 294 | Elf_Internal_Phdr *p = i_phdrp + phindex; |
| 295 | if (p->p_filesz) |
| 296 | { |
| 297 | bfd_size_type current = p->p_offset + p->p_filesz; |
| 298 | if (high < current) |
| 299 | high = current; |
| 300 | } |
| 301 | } |
| 302 | if (bfd_stat (abfd, &statbuf) == 0) |
| 303 | { |
| 304 | if ((bfd_size_type) statbuf.st_size < high) |
| 305 | { |
| 306 | _bfd_error_handler |
| 307 | /* xgettext:c-format */ |
| 308 | (_("warning: %pB is truncated: expected core file " |
| 309 | "size >= %" PRIu64 ", found: %" PRIu64), |
| 310 | abfd, (uint64_t) high, (uint64_t) statbuf.st_size); |
| 311 | } |
| 312 | } |
| 313 | } |
| 314 | |
| 315 | /* Save the entry point from the ELF header. */ |
| 316 | abfd->start_address = i_ehdrp->e_entry; |
| 317 | return abfd->xvec; |
| 318 | |
| 319 | wrong: |
| 320 | bfd_set_error (bfd_error_wrong_format); |
| 321 | fail: |
| 322 | return NULL; |
| 323 | } |
| 324 | |
| 325 | /* Attempt to find a build-id in a core file from the core file BFD. |
| 326 | OFFSET is the file offset to a PT_LOAD segment that may contain |
| 327 | the build-id note. Returns TRUE upon success, FALSE otherwise. */ |
| 328 | |
| 329 | bfd_boolean |
| 330 | NAME(_bfd_elf, core_find_build_id) |
| 331 | (bfd *abfd, |
| 332 | bfd_vma offset) |
| 333 | { |
| 334 | Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */ |
| 335 | Elf_Internal_Ehdr i_ehdr; /* Elf file header, internal form. */ |
| 336 | Elf_Internal_Phdr *i_phdr; |
| 337 | unsigned int i; |
| 338 | |
| 339 | /* Seek to the position of the segment at OFFSET. */ |
| 340 | if (bfd_seek (abfd, offset, SEEK_SET) != 0) |
| 341 | goto fail; |
| 342 | |
| 343 | /* Read in the ELF header in external format. */ |
| 344 | if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr)) |
| 345 | { |
| 346 | if (bfd_get_error () != bfd_error_system_call) |
| 347 | goto wrong; |
| 348 | else |
| 349 | goto fail; |
| 350 | } |
| 351 | |
| 352 | /* Now check to see if we have a valid ELF file, and one that BFD can |
| 353 | make use of. The magic number must match, the address size ('class') |
| 354 | and byte-swapping must match our XVEC entry, and it must have a |
| 355 | section header table (FIXME: See comments re sections at top of this |
| 356 | file). */ |
| 357 | if (! elf_file_p (&x_ehdr) |
| 358 | || x_ehdr.e_ident[EI_VERSION] != EV_CURRENT |
| 359 | || x_ehdr.e_ident[EI_CLASS] != ELFCLASS) |
| 360 | goto wrong; |
| 361 | |
| 362 | /* Check that file's byte order matches xvec's. */ |
| 363 | switch (x_ehdr.e_ident[EI_DATA]) |
| 364 | { |
| 365 | case ELFDATA2MSB: /* Big-endian. */ |
| 366 | if (! bfd_header_big_endian (abfd)) |
| 367 | goto wrong; |
| 368 | break; |
| 369 | case ELFDATA2LSB: /* Little-endian. */ |
| 370 | if (! bfd_header_little_endian (abfd)) |
| 371 | goto wrong; |
| 372 | break; |
| 373 | case ELFDATANONE: /* No data encoding specified. */ |
| 374 | default: /* Unknown data encoding specified . */ |
| 375 | goto wrong; |
| 376 | } |
| 377 | |
| 378 | elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr); |
| 379 | #if DEBUG |
| 380 | elf_debug_file (&i_ehdr); |
| 381 | #endif |
| 382 | |
| 383 | if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) || i_ehdr.e_phnum == 0) |
| 384 | goto fail; |
| 385 | |
| 386 | /* Read in program headers. */ |
| 387 | i_phdr = (Elf_Internal_Phdr *) bfd_alloc2 (abfd, i_ehdr.e_phnum, |
| 388 | sizeof (*i_phdr)); |
| 389 | if (i_phdr == NULL) |
| 390 | goto fail; |
| 391 | |
| 392 | if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff), SEEK_SET) != 0) |
| 393 | goto fail; |
| 394 | |
| 395 | /* Read in program headers and parse notes. */ |
| 396 | for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr) |
| 397 | { |
| 398 | Elf_External_Phdr x_phdr; |
| 399 | |
| 400 | if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) |
| 401 | goto fail; |
| 402 | elf_swap_phdr_in (abfd, &x_phdr, i_phdr); |
| 403 | |
| 404 | if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0) |
| 405 | { |
| 406 | elf_read_notes (abfd, offset + i_phdr->p_offset, |
| 407 | i_phdr->p_filesz, i_phdr->p_align); |
| 408 | if (abfd->build_id != NULL) |
| 409 | return TRUE; |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | /* Having gotten this far, we have a valid ELF section, but no |
| 414 | build-id was found. */ |
| 415 | goto fail; |
| 416 | |
| 417 | wrong: |
| 418 | bfd_set_error (bfd_error_wrong_format); |
| 419 | fail: |
| 420 | return FALSE; |
| 421 | } |