bfd/elfcore.h

   1 /* ELF core file support for BFD.
   2    Copyright (C) 1995-2024 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 bool
  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 (bfd_get_filename (exec_bfd), '/');
  65
  66       execname = execname ? execname + 1 : bfd_get_filename (exec_bfd);
  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 bfd_cleanup
  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   ufile_ptr filesize;
  96
  97   /* Read in the ELF header in external format.  */
  98   if (bfd_read (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
  99     {
 100       if (bfd_get_error () != bfd_error_system_call)
 101         goto wrong;
 102       else
 103         goto fail;
 104     }
 105
 106   /* Check the magic number.  */
 107   if (! elf_file_p (&x_ehdr))
 108     goto wrong;
 109
 110   /* FIXME: Check EI_VERSION here !  */
 111
 112   /* Check the address size ("class").  */
 113   if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
 114     goto wrong;
 115
 116   /* Check the byteorder.  */
 117   switch (x_ehdr.e_ident[EI_DATA])
 118     {
 119     case ELFDATA2MSB:           /* Big-endian.  */
 120       if (! bfd_big_endian (abfd))
 121         goto wrong;
 122       break;
 123     case ELFDATA2LSB:           /* Little-endian.  */
 124       if (! bfd_little_endian (abfd))
 125         goto wrong;
 126       break;
 127     default:
 128       goto wrong;
 129     }
 130
 131   /* Give abfd an elf_obj_tdata.  */
 132   if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
 133     goto fail;
 134
 135   /* Swap in the rest of the header, now that we have the byte order.  */
 136   i_ehdrp = elf_elfheader (abfd);
 137   elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);
 138
 139 #if DEBUG & 1
 140   elf_debug_file (i_ehdrp);
 141 #endif
 142
 143   ebd = get_elf_backend_data (abfd);
 144
 145   /* Check that the ELF e_machine field matches what this particular
 146      BFD format expects.  */
 147
 148   if (ebd->elf_machine_code != i_ehdrp->e_machine
 149       && (ebd->elf_machine_alt1 == 0
 150           || i_ehdrp->e_machine != ebd->elf_machine_alt1)
 151       && (ebd->elf_machine_alt2 == 0
 152           || i_ehdrp->e_machine != ebd->elf_machine_alt2)
 153       && ebd->elf_machine_code != EM_NONE)
 154     goto wrong;
 155
 156   if (ebd->elf_machine_code != EM_NONE
 157       && i_ehdrp->e_ident[EI_OSABI] != ebd->elf_osabi
 158       && ebd->elf_osabi != ELFOSABI_NONE)
 159     goto wrong;
 160
 161   /* If there is no program header, or the type is not a core file, then
 162      we are hosed.  */
 163   if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
 164     goto wrong;
 165
 166   /* Does BFD's idea of the phdr size match the size
 167      recorded in the file? */
 168   if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
 169     goto wrong;
 170
 171   /* If the program header count is PN_XNUM(0xffff), the actual
 172      count is in the first section header.  */
 173   if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM)
 174     {
 175       Elf_External_Shdr x_shdr;
 176       Elf_Internal_Shdr i_shdr;
 177       file_ptr where = (file_ptr) i_ehdrp->e_shoff;
 178
 179       if (i_ehdrp->e_shoff < sizeof (x_ehdr))
 180         goto wrong;
 181
 182       /* Seek to the section header table in the file.  */
 183       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 184         goto fail;
 185
 186       /* Read the first section header at index 0, and convert to internal
 187          form.  */
 188       if (bfd_read (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
 189         goto fail;
 190       elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);
 191
 192       if (i_shdr.sh_info != 0)
 193         {
 194           i_ehdrp->e_phnum = i_shdr.sh_info;
 195           if (i_ehdrp->e_phnum != i_shdr.sh_info)
 196             goto wrong;
 197         }
 198     }
 199
 200   /* Sanity check that we can read all of the program headers.
 201      It ought to be good enough to just read the last one.  */
 202   if (i_ehdrp->e_phnum > 1)
 203     {
 204       Elf_External_Phdr x_phdr;
 205       Elf_Internal_Phdr i_phdr;
 206       file_ptr where;
 207
 208       /* Check that we don't have a totally silly number of
 209          program headers.  */
 210       if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
 211           || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
 212         goto wrong;
 213
 214       where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr));
 215       if ((bfd_size_type) where <= i_ehdrp->e_phoff)
 216         goto wrong;
 217
 218       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 219         goto fail;
 220       if (bfd_read (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 221         goto fail;
 222     }
 223
 224   /* Move to the start of the program headers.  */
 225   if (bfd_seek (abfd, i_ehdrp->e_phoff, SEEK_SET) != 0)
 226     goto wrong;
 227
 228   /* Allocate space for the program headers.  */
 229   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
 230   i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
 231   if (!i_phdrp)
 232     goto fail;
 233
 234   elf_tdata (abfd)->phdr = i_phdrp;
 235
 236   /* Read and convert to internal form.  */
 237   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 238     {
 239       Elf_External_Phdr x_phdr;
 240
 241       if (bfd_read (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 242         goto fail;
 243
 244       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
 245     }
 246
 247   /* Set the machine architecture.  Do this before processing the
 248      program headers since we need to know the architecture type
 249      when processing the notes of some systems' core files.  */
 250   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
 251       /* It's OK if this fails for the generic target.  */
 252       && ebd->elf_machine_code != EM_NONE)
 253     goto fail;
 254
 255   /* Let the backend double check the format and override global
 256      information.  We do this before processing the program headers
 257      to allow the correct machine (as opposed to just the default
 258      machine) to be set, making it possible for grok_prstatus and
 259      grok_psinfo to rely on the mach setting.  */
 260   if (ebd->elf_backend_object_p != NULL
 261       && ! ebd->elf_backend_object_p (abfd))
 262     goto wrong;
 263
 264   /* Process each program header.  */
 265   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 266     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
 267       goto fail;
 268
 269   /* Check for core truncation.  */
 270   filesize = bfd_get_file_size (abfd);
 271   if (filesize != 0)
 272     {
 273       for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 274         {
 275           Elf_Internal_Phdr *p = i_phdrp + phindex;
 276           if (p->p_filesz
 277               && (p->p_offset >= filesize
 278                   || p->p_filesz > filesize - p->p_offset))
 279             {
 280               _bfd_error_handler (_("warning: %pB has a segment "
 281                                     "extending past end of file"), abfd);
 282               abfd->read_only = 1;
 283               break;
 284             }
 285       }
 286   }
 287
 288   /* Save the entry point from the ELF header.  */
 289   abfd->start_address = i_ehdrp->e_entry;
 290   return _bfd_no_cleanup;
 291
 292  wrong:
 293   bfd_set_error (bfd_error_wrong_format);
 294  fail:
 295   return NULL;
 296 }
 297
 298 /* Attempt to find a build-id in a core file from the core file BFD.
 299    OFFSET is the file offset to a PT_LOAD segment that may contain
 300    the build-id note.  Returns TRUE upon success, FALSE otherwise.  */
 301
 302 bool
 303 NAME(_bfd_elf, core_find_build_id)
 304   (bfd *abfd,
 305    bfd_vma offset)
 306 {
 307   Elf_External_Ehdr x_ehdr;     /* Elf file header, external form.   */
 308   Elf_Internal_Ehdr i_ehdr;     /* Elf file header, internal form.   */
 309   Elf_Internal_Phdr *i_phdr;
 310   unsigned int i;
 311   size_t amt;
 312
 313   /* Seek to the position of the segment at OFFSET.  */
 314   if (bfd_seek (abfd, offset, SEEK_SET) != 0)
 315     goto fail;
 316
 317   /* Read in the ELF header in external format.  */
 318   if (bfd_read (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
 319     {
 320       if (bfd_get_error () != bfd_error_system_call)
 321         goto wrong;
 322       else
 323         goto fail;
 324     }
 325
 326   /* Now check to see if we have a valid ELF file, and one that BFD can
 327      make use of.  The magic number must match, the address size ('class')
 328      and byte-swapping must match our XVEC entry, and it must have a
 329      section header table (FIXME: See comments re sections at top of this
 330      file).  */
 331   if (! elf_file_p (&x_ehdr)
 332       || x_ehdr.e_ident[EI_VERSION] != EV_CURRENT
 333       || x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
 334     goto wrong;
 335
 336   /* Check that file's byte order matches xvec's.  */
 337   switch (x_ehdr.e_ident[EI_DATA])
 338     {
 339     case ELFDATA2MSB:           /* Big-endian.  */
 340       if (! bfd_header_big_endian (abfd))
 341         goto wrong;
 342       break;
 343     case ELFDATA2LSB:           /* Little-endian.  */
 344       if (! bfd_header_little_endian (abfd))
 345         goto wrong;
 346       break;
 347     case ELFDATANONE:           /* No data encoding specified.  */
 348     default:                    /* Unknown data encoding specified . */
 349       goto wrong;
 350     }
 351
 352   elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr);
 353 #if DEBUG
 354   elf_debug_file (&i_ehdr);
 355 #endif
 356
 357   if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) || i_ehdr.e_phnum == 0)
 358     goto fail;
 359
 360   /* Read in program headers.  */
 361   if (_bfd_mul_overflow (i_ehdr.e_phnum, sizeof (*i_phdr), &amt))
 362     {
 363       bfd_set_error (bfd_error_file_too_big);
 364       goto fail;
 365     }
 366   i_phdr = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
 367   if (i_phdr == NULL)
 368     goto fail;
 369
 370   if (bfd_seek (abfd, offset + i_ehdr.e_phoff, SEEK_SET) != 0)
 371     goto fail;
 372
 373   /* Read in program headers and parse notes.  */
 374   for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr)
 375     {
 376       Elf_External_Phdr x_phdr;
 377
 378       if (bfd_read (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 379         goto fail;
 380       elf_swap_phdr_in (abfd, &x_phdr, i_phdr);
 381
 382       if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
 383         {
 384           elf_read_notes (abfd, offset + i_phdr->p_offset,
 385                           i_phdr->p_filesz, i_phdr->p_align);
 386
 387           /* Make sure ABFD returns to processing the program headers.  */
 388           if (bfd_seek (abfd,
 389                         offset + i_ehdr.e_phoff + (i + 1) * sizeof (x_phdr),
 390                         SEEK_SET) != 0)
 391             goto fail;
 392
 393           if (abfd->build_id != NULL)
 394             return true;
 395         }
 396     }
 397
 398   /* Having gotten this far, we have a valid ELF section, but no
 399      build-id was found.  */
 400   goto fail;
 401
 402  wrong:
 403   bfd_set_error (bfd_error_wrong_format);
 404  fail:
 405   return false;
 406 }