| 1 | /* simple-object-elf.c -- routines to manipulate ELF object files. |
| 2 | Copyright 2010 Free Software Foundation, Inc. |
| 3 | Written by Ian Lance Taylor, Google. |
| 4 | |
| 5 | This program is free software; you can redistribute it and/or modify it |
| 6 | under the terms of the GNU General Public License as published by the |
| 7 | Free Software Foundation; either version 2, or (at your option) any |
| 8 | later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program; if not, write to the Free Software |
| 17 | Foundation, 51 Franklin Street - Fifth Floor, |
| 18 | Boston, MA 02110-1301, USA. */ |
| 19 | |
| 20 | #include "config.h" |
| 21 | #include "libiberty.h" |
| 22 | #include "simple-object.h" |
| 23 | |
| 24 | #include <errno.h> |
| 25 | #include <stddef.h> |
| 26 | |
| 27 | #ifdef HAVE_STDLIB_H |
| 28 | #include <stdlib.h> |
| 29 | #endif |
| 30 | |
| 31 | #ifdef HAVE_STDINT_H |
| 32 | #include <stdint.h> |
| 33 | #endif |
| 34 | |
| 35 | #ifdef HAVE_STRING_H |
| 36 | #include <string.h> |
| 37 | #endif |
| 38 | |
| 39 | #ifdef HAVE_INTTYPES_H |
| 40 | #include <inttypes.h> |
| 41 | #endif |
| 42 | |
| 43 | #include "simple-object-common.h" |
| 44 | |
| 45 | /* ELF structures and constants. */ |
| 46 | |
| 47 | /* 32-bit ELF file header. */ |
| 48 | |
| 49 | typedef struct { |
| 50 | unsigned char e_ident[16]; /* ELF "magic number" */ |
| 51 | unsigned char e_type[2]; /* Identifies object file type */ |
| 52 | unsigned char e_machine[2]; /* Specifies required architecture */ |
| 53 | unsigned char e_version[4]; /* Identifies object file version */ |
| 54 | unsigned char e_entry[4]; /* Entry point virtual address */ |
| 55 | unsigned char e_phoff[4]; /* Program header table file offset */ |
| 56 | unsigned char e_shoff[4]; /* Section header table file offset */ |
| 57 | unsigned char e_flags[4]; /* Processor-specific flags */ |
| 58 | unsigned char e_ehsize[2]; /* ELF header size in bytes */ |
| 59 | unsigned char e_phentsize[2]; /* Program header table entry size */ |
| 60 | unsigned char e_phnum[2]; /* Program header table entry count */ |
| 61 | unsigned char e_shentsize[2]; /* Section header table entry size */ |
| 62 | unsigned char e_shnum[2]; /* Section header table entry count */ |
| 63 | unsigned char e_shstrndx[2]; /* Section header string table index */ |
| 64 | } Elf32_External_Ehdr; |
| 65 | |
| 66 | /* 64-bit ELF file header. */ |
| 67 | |
| 68 | typedef struct { |
| 69 | unsigned char e_ident[16]; /* ELF "magic number" */ |
| 70 | unsigned char e_type[2]; /* Identifies object file type */ |
| 71 | unsigned char e_machine[2]; /* Specifies required architecture */ |
| 72 | unsigned char e_version[4]; /* Identifies object file version */ |
| 73 | unsigned char e_entry[8]; /* Entry point virtual address */ |
| 74 | unsigned char e_phoff[8]; /* Program header table file offset */ |
| 75 | unsigned char e_shoff[8]; /* Section header table file offset */ |
| 76 | unsigned char e_flags[4]; /* Processor-specific flags */ |
| 77 | unsigned char e_ehsize[2]; /* ELF header size in bytes */ |
| 78 | unsigned char e_phentsize[2]; /* Program header table entry size */ |
| 79 | unsigned char e_phnum[2]; /* Program header table entry count */ |
| 80 | unsigned char e_shentsize[2]; /* Section header table entry size */ |
| 81 | unsigned char e_shnum[2]; /* Section header table entry count */ |
| 82 | unsigned char e_shstrndx[2]; /* Section header string table index */ |
| 83 | } Elf64_External_Ehdr; |
| 84 | |
| 85 | /* Indexes and values in e_ident field of Ehdr. */ |
| 86 | |
| 87 | #define EI_MAG0 0 /* File identification byte 0 index */ |
| 88 | #define ELFMAG0 0x7F /* Magic number byte 0 */ |
| 89 | |
| 90 | #define EI_MAG1 1 /* File identification byte 1 index */ |
| 91 | #define ELFMAG1 'E' /* Magic number byte 1 */ |
| 92 | |
| 93 | #define EI_MAG2 2 /* File identification byte 2 index */ |
| 94 | #define ELFMAG2 'L' /* Magic number byte 2 */ |
| 95 | |
| 96 | #define EI_MAG3 3 /* File identification byte 3 index */ |
| 97 | #define ELFMAG3 'F' /* Magic number byte 3 */ |
| 98 | |
| 99 | #define EI_CLASS 4 /* File class */ |
| 100 | #define ELFCLASSNONE 0 /* Invalid class */ |
| 101 | #define ELFCLASS32 1 /* 32-bit objects */ |
| 102 | #define ELFCLASS64 2 /* 64-bit objects */ |
| 103 | |
| 104 | #define EI_DATA 5 /* Data encoding */ |
| 105 | #define ELFDATANONE 0 /* Invalid data encoding */ |
| 106 | #define ELFDATA2LSB 1 /* 2's complement, little endian */ |
| 107 | #define ELFDATA2MSB 2 /* 2's complement, big endian */ |
| 108 | |
| 109 | #define EI_VERSION 6 /* File version */ |
| 110 | #define EV_CURRENT 1 /* Current version */ |
| 111 | |
| 112 | #define EI_OSABI 7 /* Operating System/ABI indication */ |
| 113 | |
| 114 | /* Values for e_type field of Ehdr. */ |
| 115 | |
| 116 | #define ET_REL 1 /* Relocatable file */ |
| 117 | |
| 118 | /* Special section index values. */ |
| 119 | |
| 120 | #define SHN_LORESERVE 0xFF00 /* Begin range of reserved indices */ |
| 121 | #define SHN_XINDEX 0xFFFF /* Section index is held elsewhere */ |
| 122 | |
| 123 | /* 32-bit ELF program header. */ |
| 124 | |
| 125 | typedef struct { |
| 126 | unsigned char p_type[4]; /* Identifies program segment type */ |
| 127 | unsigned char p_offset[4]; /* Segment file offset */ |
| 128 | unsigned char p_vaddr[4]; /* Segment virtual address */ |
| 129 | unsigned char p_paddr[4]; /* Segment physical address */ |
| 130 | unsigned char p_filesz[4]; /* Segment size in file */ |
| 131 | unsigned char p_memsz[4]; /* Segment size in memory */ |
| 132 | unsigned char p_flags[4]; /* Segment flags */ |
| 133 | unsigned char p_align[4]; /* Segment alignment, file & memory */ |
| 134 | } Elf32_External_Phdr; |
| 135 | |
| 136 | /* 64-bit ELF program header. */ |
| 137 | |
| 138 | typedef struct { |
| 139 | unsigned char p_type[4]; /* Identifies program segment type */ |
| 140 | unsigned char p_flags[4]; /* Segment flags */ |
| 141 | unsigned char p_offset[8]; /* Segment file offset */ |
| 142 | unsigned char p_vaddr[8]; /* Segment virtual address */ |
| 143 | unsigned char p_paddr[8]; /* Segment physical address */ |
| 144 | unsigned char p_filesz[8]; /* Segment size in file */ |
| 145 | unsigned char p_memsz[8]; /* Segment size in memory */ |
| 146 | unsigned char p_align[8]; /* Segment alignment, file & memory */ |
| 147 | } Elf64_External_Phdr; |
| 148 | |
| 149 | /* 32-bit ELF section header */ |
| 150 | |
| 151 | typedef struct { |
| 152 | unsigned char sh_name[4]; /* Section name, index in string tbl */ |
| 153 | unsigned char sh_type[4]; /* Type of section */ |
| 154 | unsigned char sh_flags[4]; /* Miscellaneous section attributes */ |
| 155 | unsigned char sh_addr[4]; /* Section virtual addr at execution */ |
| 156 | unsigned char sh_offset[4]; /* Section file offset */ |
| 157 | unsigned char sh_size[4]; /* Size of section in bytes */ |
| 158 | unsigned char sh_link[4]; /* Index of another section */ |
| 159 | unsigned char sh_info[4]; /* Additional section information */ |
| 160 | unsigned char sh_addralign[4]; /* Section alignment */ |
| 161 | unsigned char sh_entsize[4]; /* Entry size if section holds table */ |
| 162 | } Elf32_External_Shdr; |
| 163 | |
| 164 | /* 64-bit ELF section header. */ |
| 165 | |
| 166 | typedef struct { |
| 167 | unsigned char sh_name[4]; /* Section name, index in string tbl */ |
| 168 | unsigned char sh_type[4]; /* Type of section */ |
| 169 | unsigned char sh_flags[8]; /* Miscellaneous section attributes */ |
| 170 | unsigned char sh_addr[8]; /* Section virtual addr at execution */ |
| 171 | unsigned char sh_offset[8]; /* Section file offset */ |
| 172 | unsigned char sh_size[8]; /* Size of section in bytes */ |
| 173 | unsigned char sh_link[4]; /* Index of another section */ |
| 174 | unsigned char sh_info[4]; /* Additional section information */ |
| 175 | unsigned char sh_addralign[8]; /* Section alignment */ |
| 176 | unsigned char sh_entsize[8]; /* Entry size if section holds table */ |
| 177 | } Elf64_External_Shdr; |
| 178 | |
| 179 | /* Values for sh_type field. */ |
| 180 | |
| 181 | #define SHT_PROGBITS 1 /* Program data */ |
| 182 | #define SHT_STRTAB 3 /* A string table */ |
| 183 | |
| 184 | /* Functions to fetch and store different ELF types, depending on the |
| 185 | endianness and size. */ |
| 186 | |
| 187 | struct elf_type_functions |
| 188 | { |
| 189 | unsigned short (*fetch_Elf_Half) (const unsigned char *); |
| 190 | unsigned int (*fetch_Elf_Word) (const unsigned char *); |
| 191 | ulong_type (*fetch_Elf_Addr) (const unsigned char *); |
| 192 | void (*set_Elf_Half) (unsigned char *, unsigned short); |
| 193 | void (*set_Elf_Word) (unsigned char *, unsigned int); |
| 194 | void (*set_Elf_Addr) (unsigned char *, ulong_type); |
| 195 | }; |
| 196 | |
| 197 | static const struct elf_type_functions elf_big_32_functions = |
| 198 | { |
| 199 | simple_object_fetch_big_16, |
| 200 | simple_object_fetch_big_32, |
| 201 | simple_object_fetch_big_32_ulong, |
| 202 | simple_object_set_big_16, |
| 203 | simple_object_set_big_32, |
| 204 | simple_object_set_big_32_ulong |
| 205 | }; |
| 206 | |
| 207 | static const struct elf_type_functions elf_little_32_functions = |
| 208 | { |
| 209 | simple_object_fetch_little_16, |
| 210 | simple_object_fetch_little_32, |
| 211 | simple_object_fetch_little_32_ulong, |
| 212 | simple_object_set_little_16, |
| 213 | simple_object_set_little_32, |
| 214 | simple_object_set_little_32_ulong |
| 215 | }; |
| 216 | |
| 217 | #ifdef UNSIGNED_64BIT_TYPE |
| 218 | |
| 219 | static const struct elf_type_functions elf_big_64_functions = |
| 220 | { |
| 221 | simple_object_fetch_big_16, |
| 222 | simple_object_fetch_big_32, |
| 223 | simple_object_fetch_big_64, |
| 224 | simple_object_set_big_16, |
| 225 | simple_object_set_big_32, |
| 226 | simple_object_set_big_64 |
| 227 | }; |
| 228 | |
| 229 | static const struct elf_type_functions elf_little_64_functions = |
| 230 | { |
| 231 | simple_object_fetch_little_16, |
| 232 | simple_object_fetch_little_32, |
| 233 | simple_object_fetch_little_64, |
| 234 | simple_object_set_little_16, |
| 235 | simple_object_set_little_32, |
| 236 | simple_object_set_little_64 |
| 237 | }; |
| 238 | |
| 239 | #endif |
| 240 | |
| 241 | /* Hideous macro to fetch the value of a field from an external ELF |
| 242 | struct of some sort. TYPEFUNCS is the set of type functions. |
| 243 | BUFFER points to the external data. STRUCTTYPE is the appropriate |
| 244 | struct type. FIELD is a field within the struct. TYPE is the type |
| 245 | of the field in the struct: Elf_Half, Elf_Word, or Elf_Addr. */ |
| 246 | |
| 247 | #define ELF_FETCH_STRUCT_FIELD(TYPEFUNCS, STRUCTTYPE, FIELD, BUFFER, TYPE) \ |
| 248 | ((TYPEFUNCS)->fetch_ ## TYPE ((BUFFER) + offsetof (STRUCTTYPE, FIELD))) |
| 249 | |
| 250 | /* Even more hideous macro to fetch the value of FIELD from BUFFER. |
| 251 | SIZE is 32 or 64. STRUCTTYPE is the name of the struct from |
| 252 | elf/external.h: Ehdr, Shdr, etc. FIELD is the name of a field in |
| 253 | the struct. TYPE is the type of the field in the struct: Elf_Half, |
| 254 | Elf_Word, or Elf_Addr. */ |
| 255 | |
| 256 | #define ELF_FETCH_SIZED_FIELD(TYPEFUNCS, SIZE, STRUCTTYPE, BUFFER, \ |
| 257 | FIELD, TYPE) \ |
| 258 | ELF_FETCH_STRUCT_FIELD (TYPEFUNCS, \ |
| 259 | Elf ## SIZE ## _External_ ## STRUCTTYPE, \ |
| 260 | FIELD, BUFFER, TYPE) |
| 261 | |
| 262 | /* Like ELF_FETCH_SIZED_FIELD but taking an ELFCLASS value. */ |
| 263 | |
| 264 | #define ELF_FETCH_FIELD(TYPEFUNCS, CLASS, STRUCTTYPE, BUFFER, \ |
| 265 | FIELD, TYPE) \ |
| 266 | ((CLASS) == ELFCLASS32 \ |
| 267 | ? ELF_FETCH_SIZED_FIELD (TYPEFUNCS, 32, STRUCTTYPE, BUFFER, FIELD, \ |
| 268 | TYPE) \ |
| 269 | : ELF_FETCH_SIZED_FIELD (TYPEFUNCS, 64, STRUCTTYPE, BUFFER, FIELD, \ |
| 270 | TYPE)) |
| 271 | |
| 272 | /* Hideous macro to set the value of a field in an external ELF |
| 273 | structure to VAL. TYPEFUNCS is the set of type functions. BUFFER |
| 274 | points to the external data. STRUCTTYPE is the appropriate |
| 275 | structure type. FIELD is a field within the struct. TYPE is the |
| 276 | type of the field in the struct: Elf_Half, Elf_Word, or |
| 277 | Elf_Addr. */ |
| 278 | |
| 279 | #define ELF_SET_STRUCT_FIELD(TYPEFUNCS, STRUCTTYPE, FIELD, BUFFER, TYPE, VAL) \ |
| 280 | (TYPEFUNCS)->set_ ## TYPE ((BUFFER) + offsetof (STRUCTTYPE, FIELD), (VAL)) |
| 281 | |
| 282 | /* Even more hideous macro to set the value of FIELD in BUFFER to VAL. |
| 283 | SIZE is 32 or 64. STRUCTTYPE is the name of the struct from |
| 284 | elf/external.h: Ehdr, Shdr, etc. FIELD is the name of a field in |
| 285 | the struct. TYPE is the type of the field in the struct: Elf_Half, |
| 286 | Elf_Word, or Elf_Addr. */ |
| 287 | |
| 288 | #define ELF_SET_SIZED_FIELD(TYPEFUNCS, SIZE, STRUCTTYPE, BUFFER, FIELD, \ |
| 289 | TYPE, VAL) \ |
| 290 | ELF_SET_STRUCT_FIELD (TYPEFUNCS, \ |
| 291 | Elf ## SIZE ## _External_ ## STRUCTTYPE, \ |
| 292 | FIELD, BUFFER, TYPE, VAL) |
| 293 | |
| 294 | /* Like ELF_SET_SIZED_FIELD but taking an ELFCLASS value. */ |
| 295 | |
| 296 | #define ELF_SET_FIELD(TYPEFUNCS, CLASS, STRUCTTYPE, BUFFER, FIELD, \ |
| 297 | TYPE, VAL) \ |
| 298 | ((CLASS) == ELFCLASS32 \ |
| 299 | ? ELF_SET_SIZED_FIELD (TYPEFUNCS, 32, STRUCTTYPE, BUFFER, FIELD, \ |
| 300 | TYPE, VAL) \ |
| 301 | : ELF_SET_SIZED_FIELD (TYPEFUNCS, 64, STRUCTTYPE, BUFFER, FIELD, \ |
| 302 | TYPE, VAL)) |
| 303 | |
| 304 | /* Private data for an simple_object_read. */ |
| 305 | |
| 306 | struct simple_object_elf_read |
| 307 | { |
| 308 | /* Type functions. */ |
| 309 | const struct elf_type_functions* type_functions; |
| 310 | /* Elf data. */ |
| 311 | unsigned char ei_data; |
| 312 | /* Elf class. */ |
| 313 | unsigned char ei_class; |
| 314 | /* ELF OS ABI. */ |
| 315 | unsigned char ei_osabi; |
| 316 | /* Elf machine number. */ |
| 317 | unsigned short machine; |
| 318 | /* Processor specific flags. */ |
| 319 | unsigned int flags; |
| 320 | /* File offset of section headers. */ |
| 321 | ulong_type shoff; |
| 322 | /* Number of sections. */ |
| 323 | unsigned int shnum; |
| 324 | /* Index of string table section header. */ |
| 325 | unsigned int shstrndx; |
| 326 | }; |
| 327 | |
| 328 | /* Private data for an simple_object_attributes. */ |
| 329 | |
| 330 | struct simple_object_elf_attributes |
| 331 | { |
| 332 | /* Type functions. */ |
| 333 | const struct elf_type_functions* type_functions; |
| 334 | /* Elf data. */ |
| 335 | unsigned char ei_data; |
| 336 | /* Elf class. */ |
| 337 | unsigned char ei_class; |
| 338 | /* ELF OS ABI. */ |
| 339 | unsigned char ei_osabi; |
| 340 | /* Elf machine number. */ |
| 341 | unsigned short machine; |
| 342 | /* Processor specific flags. */ |
| 343 | unsigned int flags; |
| 344 | }; |
| 345 | |
| 346 | /* See if we have an ELF file. */ |
| 347 | |
| 348 | static void * |
| 349 | simple_object_elf_match (unsigned char header[SIMPLE_OBJECT_MATCH_HEADER_LEN], |
| 350 | int descriptor, off_t offset, |
| 351 | const char *segment_name ATTRIBUTE_UNUSED, |
| 352 | const char **errmsg, int *err) |
| 353 | { |
| 354 | unsigned char ei_data; |
| 355 | unsigned char ei_class; |
| 356 | const struct elf_type_functions *type_functions; |
| 357 | unsigned char ehdr[sizeof (Elf64_External_Ehdr)]; |
| 358 | struct simple_object_elf_read *eor; |
| 359 | |
| 360 | if (header[EI_MAG0] != ELFMAG0 |
| 361 | || header[EI_MAG1] != ELFMAG1 |
| 362 | || header[EI_MAG2] != ELFMAG2 |
| 363 | || header[EI_MAG3] != ELFMAG3 |
| 364 | || header[EI_VERSION] != EV_CURRENT) |
| 365 | { |
| 366 | *errmsg = NULL; |
| 367 | *err = 0; |
| 368 | return NULL; |
| 369 | } |
| 370 | |
| 371 | ei_data = header[EI_DATA]; |
| 372 | if (ei_data != ELFDATA2LSB && ei_data != ELFDATA2MSB) |
| 373 | { |
| 374 | *errmsg = "unknown ELF endianness"; |
| 375 | *err = 0; |
| 376 | return NULL; |
| 377 | } |
| 378 | |
| 379 | ei_class = header[EI_CLASS]; |
| 380 | switch (ei_class) |
| 381 | { |
| 382 | case ELFCLASS32: |
| 383 | type_functions = (ei_data == ELFDATA2LSB |
| 384 | ? &elf_little_32_functions |
| 385 | : &elf_big_32_functions); |
| 386 | break; |
| 387 | |
| 388 | case ELFCLASS64: |
| 389 | #ifndef UNSIGNED_64BIT_TYPE |
| 390 | *errmsg = "64-bit ELF objects not supported"; |
| 391 | *err = 0; |
| 392 | return NULL; |
| 393 | #else |
| 394 | type_functions = (ei_data == ELFDATA2LSB |
| 395 | ? &elf_little_64_functions |
| 396 | : &elf_big_64_functions); |
| 397 | break; |
| 398 | #endif |
| 399 | |
| 400 | default: |
| 401 | *errmsg = "unrecognized ELF size"; |
| 402 | *err = 0; |
| 403 | return NULL; |
| 404 | } |
| 405 | |
| 406 | if (!simple_object_internal_read (descriptor, offset, ehdr, sizeof ehdr, |
| 407 | errmsg, err)) |
| 408 | return NULL; |
| 409 | |
| 410 | eor = XNEW (struct simple_object_elf_read); |
| 411 | eor->type_functions = type_functions; |
| 412 | eor->ei_data = ei_data; |
| 413 | eor->ei_class = ei_class; |
| 414 | eor->ei_osabi = header[EI_OSABI]; |
| 415 | eor->machine = ELF_FETCH_FIELD (type_functions, ei_class, Ehdr, ehdr, |
| 416 | e_machine, Elf_Half); |
| 417 | eor->flags = ELF_FETCH_FIELD (type_functions, ei_class, Ehdr, ehdr, |
| 418 | e_flags, Elf_Word); |
| 419 | eor->shoff = ELF_FETCH_FIELD (type_functions, ei_class, Ehdr, ehdr, |
| 420 | e_shoff, Elf_Addr); |
| 421 | eor->shnum = ELF_FETCH_FIELD (type_functions, ei_class, Ehdr, ehdr, |
| 422 | e_shnum, Elf_Half); |
| 423 | eor->shstrndx = ELF_FETCH_FIELD (type_functions, ei_class, Ehdr, ehdr, |
| 424 | e_shstrndx, Elf_Half); |
| 425 | |
| 426 | if ((eor->shnum == 0 || eor->shstrndx == SHN_XINDEX) |
| 427 | && eor->shoff != 0) |
| 428 | { |
| 429 | unsigned char shdr[sizeof (Elf64_External_Shdr)]; |
| 430 | |
| 431 | /* Object file has more than 0xffff sections. */ |
| 432 | |
| 433 | if (!simple_object_internal_read (descriptor, offset + eor->shoff, shdr, |
| 434 | (ei_class == ELFCLASS32 |
| 435 | ? sizeof (Elf32_External_Shdr) |
| 436 | : sizeof (Elf64_External_Shdr)), |
| 437 | errmsg, err)) |
| 438 | { |
| 439 | XDELETE (eor); |
| 440 | return NULL; |
| 441 | } |
| 442 | |
| 443 | if (eor->shnum == 0) |
| 444 | eor->shnum = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 445 | shdr, sh_size, Elf_Addr); |
| 446 | |
| 447 | if (eor->shstrndx == SHN_XINDEX) |
| 448 | { |
| 449 | eor->shstrndx = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 450 | shdr, sh_link, Elf_Word); |
| 451 | |
| 452 | /* Versions of the GNU binutils between 2.12 and 2.18 did |
| 453 | not handle objects with more than SHN_LORESERVE sections |
| 454 | correctly. All large section indexes were offset by |
| 455 | 0x100. There is more information at |
| 456 | http://sourceware.org/bugzilla/show_bug.cgi?id-5900 . |
| 457 | Fortunately these object files are easy to detect, as the |
| 458 | GNU binutils always put the section header string table |
| 459 | near the end of the list of sections. Thus if the |
| 460 | section header string table index is larger than the |
| 461 | number of sections, then we know we have to subtract |
| 462 | 0x100 to get the real section index. */ |
| 463 | if (eor->shstrndx >= eor->shnum |
| 464 | && eor->shstrndx >= SHN_LORESERVE + 0x100) |
| 465 | eor->shstrndx -= 0x100; |
| 466 | } |
| 467 | } |
| 468 | |
| 469 | if (eor->shstrndx >= eor->shnum) |
| 470 | { |
| 471 | *errmsg = "invalid ELF shstrndx >= shnum"; |
| 472 | *err = 0; |
| 473 | XDELETE (eor); |
| 474 | return NULL; |
| 475 | } |
| 476 | |
| 477 | return (void *) eor; |
| 478 | } |
| 479 | |
| 480 | /* Find all sections in an ELF file. */ |
| 481 | |
| 482 | static const char * |
| 483 | simple_object_elf_find_sections (simple_object_read *sobj, |
| 484 | int (*pfn) (void *, const char *, |
| 485 | off_t offset, off_t length), |
| 486 | void *data, |
| 487 | int *err) |
| 488 | { |
| 489 | struct simple_object_elf_read *eor = |
| 490 | (struct simple_object_elf_read *) sobj->data; |
| 491 | const struct elf_type_functions *type_functions = eor->type_functions; |
| 492 | unsigned char ei_class = eor->ei_class; |
| 493 | size_t shdr_size; |
| 494 | unsigned int shnum; |
| 495 | unsigned char *shdrs; |
| 496 | const char *errmsg; |
| 497 | unsigned char *shstrhdr; |
| 498 | size_t name_size; |
| 499 | off_t shstroff; |
| 500 | unsigned char *names; |
| 501 | unsigned int i; |
| 502 | |
| 503 | shdr_size = (ei_class == ELFCLASS32 |
| 504 | ? sizeof (Elf32_External_Shdr) |
| 505 | : sizeof (Elf64_External_Shdr)); |
| 506 | |
| 507 | /* Read the section headers. We skip section 0, which is not a |
| 508 | useful section. */ |
| 509 | |
| 510 | shnum = eor->shnum; |
| 511 | shdrs = XNEWVEC (unsigned char, shdr_size * (shnum - 1)); |
| 512 | |
| 513 | if (!simple_object_internal_read (sobj->descriptor, |
| 514 | sobj->offset + eor->shoff + shdr_size, |
| 515 | shdrs, |
| 516 | shdr_size * (shnum - 1), |
| 517 | &errmsg, err)) |
| 518 | { |
| 519 | XDELETEVEC (shdrs); |
| 520 | return errmsg; |
| 521 | } |
| 522 | |
| 523 | /* Read the section names. */ |
| 524 | |
| 525 | shstrhdr = shdrs + (eor->shstrndx - 1) * shdr_size; |
| 526 | name_size = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 527 | shstrhdr, sh_size, Elf_Addr); |
| 528 | shstroff = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 529 | shstrhdr, sh_offset, Elf_Addr); |
| 530 | names = XNEWVEC (unsigned char, name_size); |
| 531 | if (!simple_object_internal_read (sobj->descriptor, |
| 532 | sobj->offset + shstroff, |
| 533 | names, name_size, &errmsg, err)) |
| 534 | { |
| 535 | XDELETEVEC (names); |
| 536 | XDELETEVEC (shdrs); |
| 537 | return errmsg; |
| 538 | } |
| 539 | |
| 540 | for (i = 1; i < shnum; ++i) |
| 541 | { |
| 542 | unsigned char *shdr; |
| 543 | unsigned int sh_name; |
| 544 | const char *name; |
| 545 | off_t offset; |
| 546 | off_t length; |
| 547 | |
| 548 | shdr = shdrs + (i - 1) * shdr_size; |
| 549 | sh_name = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 550 | shdr, sh_name, Elf_Word); |
| 551 | if (sh_name >= name_size) |
| 552 | { |
| 553 | *err = 0; |
| 554 | XDELETEVEC (names); |
| 555 | XDELETEVEC (shdrs); |
| 556 | return "ELF section name out of range"; |
| 557 | } |
| 558 | |
| 559 | name = (const char *) names + sh_name; |
| 560 | offset = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 561 | shdr, sh_offset, Elf_Addr); |
| 562 | length = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, |
| 563 | shdr, sh_size, Elf_Addr); |
| 564 | |
| 565 | if (!(*pfn) (data, name, offset, length)) |
| 566 | break; |
| 567 | } |
| 568 | |
| 569 | XDELETEVEC (names); |
| 570 | XDELETEVEC (shdrs); |
| 571 | |
| 572 | return NULL; |
| 573 | } |
| 574 | |
| 575 | /* Fetch the attributes for an simple_object_read. */ |
| 576 | |
| 577 | static void * |
| 578 | simple_object_elf_fetch_attributes (simple_object_read *sobj, |
| 579 | const char **errmsg ATTRIBUTE_UNUSED, |
| 580 | int *err ATTRIBUTE_UNUSED) |
| 581 | { |
| 582 | struct simple_object_elf_read *eor = |
| 583 | (struct simple_object_elf_read *) sobj->data; |
| 584 | struct simple_object_elf_attributes *ret; |
| 585 | |
| 586 | ret = XNEW (struct simple_object_elf_attributes); |
| 587 | ret->type_functions = eor->type_functions; |
| 588 | ret->ei_data = eor->ei_data; |
| 589 | ret->ei_class = eor->ei_class; |
| 590 | ret->ei_osabi = eor->ei_osabi; |
| 591 | ret->machine = eor->machine; |
| 592 | ret->flags = eor->flags; |
| 593 | return ret; |
| 594 | } |
| 595 | |
| 596 | /* Release the privata data for an simple_object_read. */ |
| 597 | |
| 598 | static void |
| 599 | simple_object_elf_release_read (void *data) |
| 600 | { |
| 601 | XDELETE (data); |
| 602 | } |
| 603 | |
| 604 | /* Compare two attributes structures. */ |
| 605 | |
| 606 | static const char * |
| 607 | simple_object_elf_attributes_compare (void *data1, void *data2, int *err) |
| 608 | { |
| 609 | struct simple_object_elf_attributes *attrs1 = |
| 610 | (struct simple_object_elf_attributes *) data1; |
| 611 | struct simple_object_elf_attributes *attrs2 = |
| 612 | (struct simple_object_elf_attributes *) data2; |
| 613 | |
| 614 | if (attrs1->ei_data != attrs2->ei_data |
| 615 | || attrs1->ei_class != attrs2->ei_class |
| 616 | || attrs1->machine != attrs2->machine) |
| 617 | { |
| 618 | *err = 0; |
| 619 | return "ELF object format mismatch"; |
| 620 | } |
| 621 | return NULL; |
| 622 | } |
| 623 | |
| 624 | /* Release the private data for an attributes structure. */ |
| 625 | |
| 626 | static void |
| 627 | simple_object_elf_release_attributes (void *data) |
| 628 | { |
| 629 | XDELETE (data); |
| 630 | } |
| 631 | |
| 632 | /* Prepare to write out a file. */ |
| 633 | |
| 634 | static void * |
| 635 | simple_object_elf_start_write (void *attributes_data, |
| 636 | const char **errmsg ATTRIBUTE_UNUSED, |
| 637 | int *err ATTRIBUTE_UNUSED) |
| 638 | { |
| 639 | struct simple_object_elf_attributes *attrs = |
| 640 | (struct simple_object_elf_attributes *) attributes_data; |
| 641 | struct simple_object_elf_attributes *ret; |
| 642 | |
| 643 | /* We're just going to record the attributes, but we need to make a |
| 644 | copy because the user may delete them. */ |
| 645 | ret = XNEW (struct simple_object_elf_attributes); |
| 646 | *ret = *attrs; |
| 647 | return ret; |
| 648 | } |
| 649 | |
| 650 | /* Write out an ELF ehdr. */ |
| 651 | |
| 652 | static int |
| 653 | simple_object_elf_write_ehdr (simple_object_write *sobj, int descriptor, |
| 654 | const char **errmsg, int *err) |
| 655 | { |
| 656 | struct simple_object_elf_attributes *attrs = |
| 657 | (struct simple_object_elf_attributes *) sobj->data; |
| 658 | const struct elf_type_functions* fns; |
| 659 | unsigned char cl; |
| 660 | size_t ehdr_size; |
| 661 | unsigned char buf[sizeof (Elf64_External_Ehdr)]; |
| 662 | simple_object_write_section *section; |
| 663 | unsigned int shnum; |
| 664 | |
| 665 | fns = attrs->type_functions; |
| 666 | cl = attrs->ei_class; |
| 667 | |
| 668 | shnum = 0; |
| 669 | for (section = sobj->sections; section != NULL; section = section->next) |
| 670 | ++shnum; |
| 671 | if (shnum > 0) |
| 672 | { |
| 673 | /* Add a section header for the dummy section and one for |
| 674 | .shstrtab. */ |
| 675 | shnum += 2; |
| 676 | } |
| 677 | |
| 678 | ehdr_size = (cl == ELFCLASS32 |
| 679 | ? sizeof (Elf32_External_Ehdr) |
| 680 | : sizeof (Elf64_External_Ehdr)); |
| 681 | memset (buf, 0, sizeof (Elf64_External_Ehdr)); |
| 682 | |
| 683 | buf[EI_MAG0] = ELFMAG0; |
| 684 | buf[EI_MAG1] = ELFMAG1; |
| 685 | buf[EI_MAG2] = ELFMAG2; |
| 686 | buf[EI_MAG3] = ELFMAG3; |
| 687 | buf[EI_CLASS] = cl; |
| 688 | buf[EI_DATA] = attrs->ei_data; |
| 689 | buf[EI_VERSION] = EV_CURRENT; |
| 690 | buf[EI_OSABI] = attrs->ei_osabi; |
| 691 | |
| 692 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_type, Elf_Half, ET_REL); |
| 693 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_machine, Elf_Half, attrs->machine); |
| 694 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_version, Elf_Word, EV_CURRENT); |
| 695 | /* e_entry left as zero. */ |
| 696 | /* e_phoff left as zero. */ |
| 697 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_shoff, Elf_Addr, ehdr_size); |
| 698 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_flags, Elf_Word, attrs->flags); |
| 699 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_ehsize, Elf_Half, ehdr_size); |
| 700 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_phentsize, Elf_Half, |
| 701 | (cl == ELFCLASS32 |
| 702 | ? sizeof (Elf32_External_Phdr) |
| 703 | : sizeof (Elf64_External_Phdr))); |
| 704 | /* e_phnum left as zero. */ |
| 705 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_shentsize, Elf_Half, |
| 706 | (cl == ELFCLASS32 |
| 707 | ? sizeof (Elf32_External_Shdr) |
| 708 | : sizeof (Elf64_External_Shdr))); |
| 709 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_shnum, Elf_Half, shnum); |
| 710 | ELF_SET_FIELD (fns, cl, Ehdr, buf, e_shstrndx, Elf_Half, |
| 711 | shnum == 0 ? 0 : shnum - 1); |
| 712 | |
| 713 | return simple_object_internal_write (descriptor, 0, buf, ehdr_size, |
| 714 | errmsg, err); |
| 715 | } |
| 716 | |
| 717 | /* Write out an ELF shdr. */ |
| 718 | |
| 719 | static int |
| 720 | simple_object_elf_write_shdr (simple_object_write *sobj, int descriptor, |
| 721 | off_t offset, unsigned int sh_name, |
| 722 | unsigned int sh_type, unsigned int sh_flags, |
| 723 | unsigned int sh_offset, unsigned int sh_size, |
| 724 | unsigned int sh_addralign, const char **errmsg, |
| 725 | int *err) |
| 726 | { |
| 727 | struct simple_object_elf_attributes *attrs = |
| 728 | (struct simple_object_elf_attributes *) sobj->data; |
| 729 | const struct elf_type_functions* fns; |
| 730 | unsigned char cl; |
| 731 | size_t shdr_size; |
| 732 | unsigned char buf[sizeof (Elf64_External_Shdr)]; |
| 733 | |
| 734 | fns = attrs->type_functions; |
| 735 | cl = attrs->ei_class; |
| 736 | |
| 737 | shdr_size = (cl == ELFCLASS32 |
| 738 | ? sizeof (Elf32_External_Shdr) |
| 739 | : sizeof (Elf64_External_Shdr)); |
| 740 | memset (buf, 0, sizeof (Elf64_External_Shdr)); |
| 741 | |
| 742 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_name, Elf_Word, sh_name); |
| 743 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_type, Elf_Word, sh_type); |
| 744 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_flags, Elf_Addr, sh_flags); |
| 745 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_offset, Elf_Addr, sh_offset); |
| 746 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_size, Elf_Addr, sh_size); |
| 747 | /* sh_link left as zero. */ |
| 748 | /* sh_info left as zero. */ |
| 749 | ELF_SET_FIELD (fns, cl, Shdr, buf, sh_addralign, Elf_Addr, sh_addralign); |
| 750 | /* sh_entsize left as zero. */ |
| 751 | |
| 752 | return simple_object_internal_write (descriptor, offset, buf, shdr_size, |
| 753 | errmsg, err); |
| 754 | } |
| 755 | |
| 756 | /* Write out a complete ELF file. |
| 757 | Ehdr |
| 758 | initial dummy Shdr |
| 759 | user-created Shdrs |
| 760 | .shstrtab Shdr |
| 761 | user-created section data |
| 762 | .shstrtab data */ |
| 763 | |
| 764 | static const char * |
| 765 | simple_object_elf_write_to_file (simple_object_write *sobj, int descriptor, |
| 766 | int *err) |
| 767 | { |
| 768 | struct simple_object_elf_attributes *attrs = |
| 769 | (struct simple_object_elf_attributes *) sobj->data; |
| 770 | unsigned char cl; |
| 771 | size_t ehdr_size; |
| 772 | size_t shdr_size; |
| 773 | const char *errmsg; |
| 774 | simple_object_write_section *section; |
| 775 | unsigned int shnum; |
| 776 | size_t shdr_offset; |
| 777 | size_t sh_offset; |
| 778 | size_t sh_name; |
| 779 | unsigned char zero; |
| 780 | |
| 781 | if (!simple_object_elf_write_ehdr (sobj, descriptor, &errmsg, err)) |
| 782 | return errmsg; |
| 783 | |
| 784 | cl = attrs->ei_class; |
| 785 | if (cl == ELFCLASS32) |
| 786 | { |
| 787 | ehdr_size = sizeof (Elf32_External_Ehdr); |
| 788 | shdr_size = sizeof (Elf32_External_Shdr); |
| 789 | } |
| 790 | else |
| 791 | { |
| 792 | ehdr_size = sizeof (Elf64_External_Ehdr); |
| 793 | shdr_size = sizeof (Elf64_External_Shdr); |
| 794 | } |
| 795 | |
| 796 | shnum = 0; |
| 797 | for (section = sobj->sections; section != NULL; section = section->next) |
| 798 | ++shnum; |
| 799 | if (shnum == 0) |
| 800 | return NULL; |
| 801 | |
| 802 | /* Add initial dummy Shdr and .shstrtab. */ |
| 803 | shnum += 2; |
| 804 | |
| 805 | shdr_offset = ehdr_size; |
| 806 | sh_offset = shdr_offset + shnum * shdr_size; |
| 807 | |
| 808 | if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, |
| 809 | 0, 0, 0, 0, 0, 0, &errmsg, err)) |
| 810 | return errmsg; |
| 811 | |
| 812 | shdr_offset += shdr_size; |
| 813 | |
| 814 | sh_name = 1; |
| 815 | for (section = sobj->sections; section != NULL; section = section->next) |
| 816 | { |
| 817 | size_t mask; |
| 818 | size_t new_sh_offset; |
| 819 | size_t sh_size; |
| 820 | struct simple_object_write_section_buffer *buffer; |
| 821 | |
| 822 | mask = (1U << section->align) - 1; |
| 823 | new_sh_offset = sh_offset + mask; |
| 824 | new_sh_offset &= ~ mask; |
| 825 | while (new_sh_offset > sh_offset) |
| 826 | { |
| 827 | unsigned char zeroes[16]; |
| 828 | size_t write; |
| 829 | |
| 830 | memset (zeroes, 0, sizeof zeroes); |
| 831 | write = new_sh_offset - sh_offset; |
| 832 | if (write > sizeof zeroes) |
| 833 | write = sizeof zeroes; |
| 834 | if (!simple_object_internal_write (descriptor, sh_offset, zeroes, |
| 835 | write, &errmsg, err)) |
| 836 | return errmsg; |
| 837 | sh_offset += write; |
| 838 | } |
| 839 | |
| 840 | sh_size = 0; |
| 841 | for (buffer = section->buffers; buffer != NULL; buffer = buffer->next) |
| 842 | { |
| 843 | if (!simple_object_internal_write (descriptor, sh_offset + sh_size, |
| 844 | ((const unsigned char *) |
| 845 | buffer->buffer), |
| 846 | buffer->size, &errmsg, err)) |
| 847 | return errmsg; |
| 848 | sh_size += buffer->size; |
| 849 | } |
| 850 | |
| 851 | if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, |
| 852 | sh_name, SHT_PROGBITS, 0, sh_offset, |
| 853 | sh_size, 1U << section->align, |
| 854 | &errmsg, err)) |
| 855 | return errmsg; |
| 856 | |
| 857 | shdr_offset += shdr_size; |
| 858 | sh_name += strlen (section->name) + 1; |
| 859 | sh_offset += sh_size; |
| 860 | } |
| 861 | |
| 862 | if (!simple_object_elf_write_shdr (sobj, descriptor, shdr_offset, |
| 863 | sh_name, SHT_STRTAB, 0, sh_offset, |
| 864 | sh_name + strlen (".shstrtab") + 1, |
| 865 | 1, &errmsg, err)) |
| 866 | return errmsg; |
| 867 | |
| 868 | /* .shstrtab has a leading zero byte. */ |
| 869 | zero = 0; |
| 870 | if (!simple_object_internal_write (descriptor, sh_offset, &zero, 1, |
| 871 | &errmsg, err)) |
| 872 | return errmsg; |
| 873 | ++sh_offset; |
| 874 | |
| 875 | for (section = sobj->sections; section != NULL; section = section->next) |
| 876 | { |
| 877 | size_t len; |
| 878 | |
| 879 | len = strlen (section->name) + 1; |
| 880 | if (!simple_object_internal_write (descriptor, sh_offset, |
| 881 | (const unsigned char *) section->name, |
| 882 | len, &errmsg, err)) |
| 883 | return errmsg; |
| 884 | sh_offset += len; |
| 885 | } |
| 886 | |
| 887 | if (!simple_object_internal_write (descriptor, sh_offset, |
| 888 | (const unsigned char *) ".shstrtab", |
| 889 | strlen (".shstrtab") + 1, &errmsg, err)) |
| 890 | return errmsg; |
| 891 | |
| 892 | return NULL; |
| 893 | } |
| 894 | |
| 895 | /* Release the private data for an simple_object_write structure. */ |
| 896 | |
| 897 | static void |
| 898 | simple_object_elf_release_write (void *data) |
| 899 | { |
| 900 | XDELETE (data); |
| 901 | } |
| 902 | |
| 903 | /* The ELF functions. */ |
| 904 | |
| 905 | const struct simple_object_functions simple_object_elf_functions = |
| 906 | { |
| 907 | simple_object_elf_match, |
| 908 | simple_object_elf_find_sections, |
| 909 | simple_object_elf_fetch_attributes, |
| 910 | simple_object_elf_release_read, |
| 911 | simple_object_elf_attributes_compare, |
| 912 | simple_object_elf_release_attributes, |
| 913 | simple_object_elf_start_write, |
| 914 | simple_object_elf_write_to_file, |
| 915 | simple_object_elf_release_write |
| 916 | }; |