| 1 | /* ELF core file support for BFD. |
| 2 | Copyright (C) 1995-2017 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 | /* See if the name in the corefile matches the executable name. */ |
| 53 | corename = elf_tdata (core_bfd)->core->program; |
| 54 | if (corename != NULL) |
| 55 | { |
| 56 | const char* execname = strrchr (exec_bfd->filename, '/'); |
| 57 | |
| 58 | execname = execname ? execname + 1 : exec_bfd->filename; |
| 59 | |
| 60 | if (strcmp (execname, corename) != 0) |
| 61 | return FALSE; |
| 62 | } |
| 63 | |
| 64 | return TRUE; |
| 65 | } |
| 66 | |
| 67 | /* Core files are simply standard ELF formatted files that partition |
| 68 | the file using the execution view of the file (program header table) |
| 69 | rather than the linking view. In fact, there is no section header |
| 70 | table in a core file. |
| 71 | |
| 72 | The process status information (including the contents of the general |
| 73 | register set) and the floating point register set are stored in a |
| 74 | segment of type PT_NOTE. We handcraft a couple of extra bfd sections |
| 75 | that allow standard bfd access to the general registers (.reg) and the |
| 76 | floating point registers (.reg2). */ |
| 77 | |
| 78 | const bfd_target * |
| 79 | elf_core_file_p (bfd *abfd) |
| 80 | { |
| 81 | Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */ |
| 82 | Elf_Internal_Ehdr *i_ehdrp; /* Elf file header, internal form. */ |
| 83 | Elf_Internal_Phdr *i_phdrp; /* Elf program header, internal form. */ |
| 84 | unsigned int phindex; |
| 85 | const struct elf_backend_data *ebd; |
| 86 | bfd_size_type amt; |
| 87 | |
| 88 | /* Read in the ELF header in external format. */ |
| 89 | if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr)) |
| 90 | { |
| 91 | if (bfd_get_error () != bfd_error_system_call) |
| 92 | goto wrong; |
| 93 | else |
| 94 | goto fail; |
| 95 | } |
| 96 | |
| 97 | /* Check the magic number. */ |
| 98 | if (! elf_file_p (&x_ehdr)) |
| 99 | goto wrong; |
| 100 | |
| 101 | /* FIXME: Check EI_VERSION here ! */ |
| 102 | |
| 103 | /* Check the address size ("class"). */ |
| 104 | if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS) |
| 105 | goto wrong; |
| 106 | |
| 107 | /* Check the byteorder. */ |
| 108 | switch (x_ehdr.e_ident[EI_DATA]) |
| 109 | { |
| 110 | case ELFDATA2MSB: /* Big-endian. */ |
| 111 | if (! bfd_big_endian (abfd)) |
| 112 | goto wrong; |
| 113 | break; |
| 114 | case ELFDATA2LSB: /* Little-endian. */ |
| 115 | if (! bfd_little_endian (abfd)) |
| 116 | goto wrong; |
| 117 | break; |
| 118 | default: |
| 119 | goto wrong; |
| 120 | } |
| 121 | |
| 122 | /* Give abfd an elf_obj_tdata. */ |
| 123 | if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd)) |
| 124 | goto fail; |
| 125 | |
| 126 | /* Swap in the rest of the header, now that we have the byte order. */ |
| 127 | i_ehdrp = elf_elfheader (abfd); |
| 128 | elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp); |
| 129 | |
| 130 | #if DEBUG & 1 |
| 131 | elf_debug_file (i_ehdrp); |
| 132 | #endif |
| 133 | |
| 134 | ebd = get_elf_backend_data (abfd); |
| 135 | |
| 136 | /* Check that the ELF e_machine field matches what this particular |
| 137 | BFD format expects. */ |
| 138 | |
| 139 | if (ebd->elf_machine_code != i_ehdrp->e_machine |
| 140 | && (ebd->elf_machine_alt1 == 0 |
| 141 | || i_ehdrp->e_machine != ebd->elf_machine_alt1) |
| 142 | && (ebd->elf_machine_alt2 == 0 |
| 143 | || i_ehdrp->e_machine != ebd->elf_machine_alt2)) |
| 144 | { |
| 145 | const bfd_target * const *target_ptr; |
| 146 | |
| 147 | if (ebd->elf_machine_code != EM_NONE) |
| 148 | goto wrong; |
| 149 | |
| 150 | /* This is the generic ELF target. Let it match any ELF target |
| 151 | for which we do not have a specific backend. */ |
| 152 | |
| 153 | for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++) |
| 154 | { |
| 155 | const struct elf_backend_data *back; |
| 156 | |
| 157 | if ((*target_ptr)->flavour != bfd_target_elf_flavour) |
| 158 | continue; |
| 159 | back = xvec_get_elf_backend_data (*target_ptr); |
| 160 | if (back->s->arch_size != ARCH_SIZE) |
| 161 | continue; |
| 162 | if (back->elf_machine_code == i_ehdrp->e_machine |
| 163 | || (back->elf_machine_alt1 != 0 |
| 164 | && i_ehdrp->e_machine == back->elf_machine_alt1) |
| 165 | || (back->elf_machine_alt2 != 0 |
| 166 | && i_ehdrp->e_machine == back->elf_machine_alt2)) |
| 167 | { |
| 168 | /* target_ptr is an ELF backend which matches this |
| 169 | object file, so reject the generic ELF target. */ |
| 170 | goto wrong; |
| 171 | } |
| 172 | } |
| 173 | } |
| 174 | |
| 175 | /* If there is no program header, or the type is not a core file, then |
| 176 | we are hosed. */ |
| 177 | if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE) |
| 178 | goto wrong; |
| 179 | |
| 180 | /* Does BFD's idea of the phdr size match the size |
| 181 | recorded in the file? */ |
| 182 | if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr)) |
| 183 | goto wrong; |
| 184 | |
| 185 | /* If the program header count is PN_XNUM(0xffff), the actual |
| 186 | count is in the first section header. */ |
| 187 | if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM) |
| 188 | { |
| 189 | Elf_External_Shdr x_shdr; |
| 190 | Elf_Internal_Shdr i_shdr; |
| 191 | file_ptr where = (file_ptr) i_ehdrp->e_shoff; |
| 192 | |
| 193 | /* Seek to the section header table in the file. */ |
| 194 | if (bfd_seek (abfd, where, SEEK_SET) != 0) |
| 195 | goto fail; |
| 196 | |
| 197 | /* Read the first section header at index 0, and convert to internal |
| 198 | form. */ |
| 199 | if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr)) |
| 200 | goto fail; |
| 201 | elf_swap_shdr_in (abfd, &x_shdr, &i_shdr); |
| 202 | |
| 203 | if (i_shdr.sh_info != 0) |
| 204 | { |
| 205 | i_ehdrp->e_phnum = i_shdr.sh_info; |
| 206 | if (i_ehdrp->e_phnum != i_shdr.sh_info) |
| 207 | goto wrong; |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | /* Sanity check that we can read all of the program headers. |
| 212 | It ought to be good enough to just read the last one. */ |
| 213 | if (i_ehdrp->e_phnum > 1) |
| 214 | { |
| 215 | Elf_External_Phdr x_phdr; |
| 216 | Elf_Internal_Phdr i_phdr; |
| 217 | file_ptr where; |
| 218 | |
| 219 | /* Check that we don't have a totally silly number of |
| 220 | program headers. */ |
| 221 | if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr) |
| 222 | || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr)) |
| 223 | goto wrong; |
| 224 | |
| 225 | where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr)); |
| 226 | if ((bfd_size_type) where <= i_ehdrp->e_phoff) |
| 227 | goto wrong; |
| 228 | |
| 229 | if (bfd_seek (abfd, where, SEEK_SET) != 0) |
| 230 | goto fail; |
| 231 | if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) |
| 232 | goto fail; |
| 233 | } |
| 234 | |
| 235 | /* Move to the start of the program headers. */ |
| 236 | if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0) |
| 237 | goto wrong; |
| 238 | |
| 239 | /* Allocate space for the program headers. */ |
| 240 | amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum; |
| 241 | i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt); |
| 242 | if (!i_phdrp) |
| 243 | goto fail; |
| 244 | |
| 245 | elf_tdata (abfd)->phdr = i_phdrp; |
| 246 | |
| 247 | /* Read and convert to internal form. */ |
| 248 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 249 | { |
| 250 | Elf_External_Phdr x_phdr; |
| 251 | |
| 252 | if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr)) |
| 253 | goto fail; |
| 254 | |
| 255 | elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex); |
| 256 | } |
| 257 | |
| 258 | /* Set the machine architecture. Do this before processing the |
| 259 | program headers since we need to know the architecture type |
| 260 | when processing the notes of some systems' core files. */ |
| 261 | if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0) |
| 262 | /* It's OK if this fails for the generic target. */ |
| 263 | && ebd->elf_machine_code != EM_NONE) |
| 264 | goto fail; |
| 265 | |
| 266 | /* Let the backend double check the format and override global |
| 267 | information. We do this before processing the program headers |
| 268 | to allow the correct machine (as opposed to just the default |
| 269 | machine) to be set, making it possible for grok_prstatus and |
| 270 | grok_psinfo to rely on the mach setting. */ |
| 271 | if (ebd->elf_backend_object_p != NULL |
| 272 | && ! ebd->elf_backend_object_p (abfd)) |
| 273 | goto wrong; |
| 274 | |
| 275 | /* Process each program header. */ |
| 276 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 277 | if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex)) |
| 278 | goto fail; |
| 279 | |
| 280 | /* Check for core truncation. */ |
| 281 | { |
| 282 | bfd_size_type high = 0; |
| 283 | struct stat statbuf; |
| 284 | for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex) |
| 285 | { |
| 286 | Elf_Internal_Phdr *p = i_phdrp + phindex; |
| 287 | if (p->p_filesz) |
| 288 | { |
| 289 | bfd_size_type current = p->p_offset + p->p_filesz; |
| 290 | if (high < current) |
| 291 | high = current; |
| 292 | } |
| 293 | } |
| 294 | if (bfd_stat (abfd, &statbuf) == 0) |
| 295 | { |
| 296 | if ((bfd_size_type) statbuf.st_size < high) |
| 297 | { |
| 298 | _bfd_error_handler |
| 299 | /* xgettext:c-format */ |
| 300 | (_("Warning: %B is truncated: expected core file " |
| 301 | "size >= %lu, found: %lu."), |
| 302 | abfd, (unsigned long) high, (unsigned long) statbuf.st_size); |
| 303 | } |
| 304 | } |
| 305 | } |
| 306 | |
| 307 | /* Save the entry point from the ELF header. */ |
| 308 | bfd_get_start_address (abfd) = i_ehdrp->e_entry; |
| 309 | return abfd->xvec; |
| 310 | |
| 311 | wrong: |
| 312 | bfd_set_error (bfd_error_wrong_format); |
| 313 | fail: |
| 314 | return NULL; |
| 315 | } |