1 /* Update data structures for changes. 2 Copyright (C) 2000-2010, 2015 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper (at) redhat.com>, 2000. 5 6 This file is free software; you can redistribute it and/or modify 7 it under the terms of either 8 9 * the GNU Lesser General Public License as published by the Free 10 Software Foundation; either version 3 of the License, or (at 11 your option) any later version 12 13 or 14 15 * the GNU General Public License as published by the Free 16 Software Foundation; either version 2 of the License, or (at 17 your option) any later version 18 19 or both in parallel, as here. 20 21 elfutils is distributed in the hope that it will be useful, but 22 WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 General Public License for more details. 25 26 You should have received copies of the GNU General Public License and 27 the GNU Lesser General Public License along with this program. If 28 not, see <http://www.gnu.org/licenses/>. */ 29 30 #ifdef HAVE_CONFIG_H 31 # include <config.h> 32 #endif 33 34 #include <assert.h> 35 #include <endian.h> 36 #include <libelf.h> 37 #include <stdbool.h> 38 #include <string.h> 39 #include <sys/param.h> 40 41 #include "libelfP.h" 42 #include "elf-knowledge.h" 43 44 #ifndef LIBELFBITS 45 # define LIBELFBITS 32 46 #endif 47 48 49 50 static int 51 ELFW(default_ehdr,LIBELFBITS) (Elf *elf, ElfW2(LIBELFBITS,Ehdr) *ehdr, 52 size_t shnum, int *change_bop) 53 { 54 /* Always write the magic bytes. */ 55 if (memcmp (&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0) 56 { 57 memcpy (&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG); 58 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ELF_F_DIRTY; 59 } 60 61 /* Always set the file class. */ 62 update_if_changed (ehdr->e_ident[EI_CLASS], ELFW(ELFCLASS,LIBELFBITS), 63 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags); 64 65 /* Set the data encoding if necessary. */ 66 if (unlikely (ehdr->e_ident[EI_DATA] == ELFDATANONE)) 67 { 68 ehdr->e_ident[EI_DATA] = 69 BYTE_ORDER == BIG_ENDIAN ? ELFDATA2MSB : ELFDATA2LSB; 70 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ELF_F_DIRTY; 71 } 72 else if (unlikely (ehdr->e_ident[EI_DATA] >= ELFDATANUM)) 73 { 74 __libelf_seterrno (ELF_E_DATA_ENCODING); 75 return 1; 76 } 77 else 78 *change_bop = ((BYTE_ORDER == LITTLE_ENDIAN 79 && ehdr->e_ident[EI_DATA] != ELFDATA2LSB) 80 || (BYTE_ORDER == BIG_ENDIAN 81 && ehdr->e_ident[EI_DATA] != ELFDATA2MSB)); 82 83 /* Unconditionally overwrite the ELF version. */ 84 update_if_changed (ehdr->e_ident[EI_VERSION], EV_CURRENT, 85 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags); 86 87 if (unlikely (ehdr->e_version == EV_NONE)) 88 { 89 ehdr->e_version = EV_CURRENT; 90 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ELF_F_DIRTY; 91 } 92 else if (unlikely (ehdr->e_version >= EV_NUM)) 93 { 94 __libelf_seterrno (ELF_E_UNKNOWN_VERSION); 95 return 1; 96 } 97 98 if (unlikely (shnum >= SHN_LORESERVE)) 99 { 100 update_if_changed (ehdr->e_shnum, 0, 101 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags); 102 } 103 else 104 update_if_changed (ehdr->e_shnum, shnum, 105 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags); 106 107 if (unlikely (ehdr->e_ehsize != elf_typesize (LIBELFBITS, ELF_T_EHDR, 1))) 108 { 109 ehdr->e_ehsize = elf_typesize (LIBELFBITS, ELF_T_EHDR, 1); 110 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ELF_F_DIRTY; 111 } 112 113 /* If phnum is zero make sure e_phoff is also zero and not some random 114 value. That would cause trouble in update_file. */ 115 if (ehdr->e_phnum == 0 && ehdr->e_phoff != 0) 116 { 117 ehdr->e_phoff = 0; 118 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ELF_F_DIRTY; 119 } 120 121 return 0; 122 } 123 124 125 off_t 126 internal_function 127 __elfw2(LIBELFBITS,updatenull_wrlock) (Elf *elf, int *change_bop, size_t shnum) 128 { 129 ElfW2(LIBELFBITS,Ehdr) *ehdr; 130 int changed = 0; 131 int ehdr_flags = 0; 132 133 ehdr = __elfw2(LIBELFBITS,getehdr_wrlock) (elf); 134 135 /* Set the default values. */ 136 if (ELFW(default_ehdr,LIBELFBITS) (elf, ehdr, shnum, change_bop) != 0) 137 return -1; 138 139 /* At least the ELF header is there. */ 140 off_t size = elf_typesize (LIBELFBITS, ELF_T_EHDR, 1); 141 142 /* Set the program header position. */ 143 if (elf->state.ELFW(elf,LIBELFBITS).phdr == NULL 144 && (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN 145 || ehdr->e_type == ET_CORE)) 146 (void) __elfw2(LIBELFBITS,getphdr_wrlock) (elf); 147 if (elf->state.ELFW(elf,LIBELFBITS).phdr != NULL) 148 { 149 /* Only executables, shared objects, and core files have a program 150 header. */ 151 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN 152 && unlikely (ehdr->e_type != ET_CORE)) 153 { 154 __libelf_seterrno (ELF_E_INVALID_PHDR); 155 return -1; 156 } 157 158 size_t phnum; 159 if (unlikely (__elf_getphdrnum_rdlock (elf, &phnum) != 0)) 160 return -1; 161 162 if (elf->flags & ELF_F_LAYOUT) 163 { 164 /* The user is supposed to fill out e_phoff. Use it and 165 e_phnum to determine the maximum extend. */ 166 size = MAX ((size_t) size, 167 ehdr->e_phoff 168 + elf_typesize (LIBELFBITS, ELF_T_PHDR, phnum)); 169 } 170 else 171 { 172 update_if_changed (ehdr->e_phoff, 173 elf_typesize (LIBELFBITS, ELF_T_EHDR, 1), 174 ehdr_flags); 175 176 /* We need no alignment here. */ 177 size += elf_typesize (LIBELFBITS, ELF_T_PHDR, phnum); 178 } 179 } 180 181 if (shnum > 0) 182 { 183 Elf_ScnList *list; 184 bool first = true; 185 186 assert (elf->state.ELFW(elf,LIBELFBITS).scns.cnt > 0); 187 188 if (shnum >= SHN_LORESERVE) 189 { 190 /* We have to fill in the number of sections in the header 191 of the zeroth section. */ 192 Elf_Scn *scn0 = &elf->state.ELFW(elf,LIBELFBITS).scns.data[0]; 193 194 update_if_changed (scn0->shdr.ELFW(e,LIBELFBITS)->sh_size, 195 shnum, scn0->shdr_flags); 196 } 197 198 /* Go over all sections and find out how large they are. */ 199 list = &elf->state.ELFW(elf,LIBELFBITS).scns; 200 201 /* Load the section headers if necessary. This loads the 202 headers for all sections. */ 203 if (list->data[1].shdr.ELFW(e,LIBELFBITS) == NULL) 204 (void) __elfw2(LIBELFBITS,getshdr_wrlock) (&list->data[1]); 205 206 do 207 { 208 for (size_t cnt = first == true; cnt < list->cnt; ++cnt) 209 { 210 Elf_Scn *scn = &list->data[cnt]; 211 ElfW2(LIBELFBITS,Shdr) *shdr = scn->shdr.ELFW(e,LIBELFBITS); 212 off_t offset = 0; 213 214 assert (shdr != NULL); 215 ElfW2(LIBELFBITS,Word) sh_entsize = shdr->sh_entsize; 216 ElfW2(LIBELFBITS,Word) sh_align = shdr->sh_addralign ?: 1; 217 if (unlikely (! powerof2 (sh_align))) 218 { 219 __libelf_seterrno (ELF_E_INVALID_ALIGN); 220 return -1; 221 } 222 223 /* Set the sh_entsize value if we can reliably detect it. */ 224 switch (shdr->sh_type) 225 { 226 case SHT_SYMTAB: 227 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_SYM, 1); 228 break; 229 case SHT_RELA: 230 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_RELA, 1); 231 break; 232 case SHT_GROUP: 233 /* Only relocatable files can contain section groups. */ 234 if (ehdr->e_type != ET_REL) 235 { 236 __libelf_seterrno (ELF_E_GROUP_NOT_REL); 237 return -1; 238 } 239 /* FALLTHROUGH */ 240 case SHT_SYMTAB_SHNDX: 241 sh_entsize = elf_typesize (32, ELF_T_WORD, 1); 242 break; 243 case SHT_HASH: 244 sh_entsize = SH_ENTSIZE_HASH (ehdr); 245 break; 246 case SHT_DYNAMIC: 247 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_DYN, 1); 248 break; 249 case SHT_REL: 250 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_REL, 1); 251 break; 252 case SHT_DYNSYM: 253 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_SYM, 1); 254 break; 255 case SHT_SUNW_move: 256 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_MOVE, 1); 257 break; 258 case SHT_SUNW_syminfo: 259 sh_entsize = elf_typesize (LIBELFBITS, ELF_T_SYMINFO, 1); 260 break; 261 default: 262 break; 263 } 264 265 /* If the section header contained the wrong entry size 266 correct it and mark the header as modified. */ 267 update_if_changed (shdr->sh_entsize, sh_entsize, 268 scn->shdr_flags); 269 270 if (scn->data_read == 0 271 && __libelf_set_rawdata_wrlock (scn) != 0) 272 /* Something went wrong. The error value is already set. */ 273 return -1; 274 275 /* Iterate over all data blocks. */ 276 if (list->data[cnt].data_list_rear != NULL) 277 { 278 Elf_Data_List *dl = &scn->data_list; 279 280 while (dl != NULL) 281 { 282 Elf_Data *data = &dl->data.d; 283 if (dl == &scn->data_list && data->d_buf == NULL 284 && scn->rawdata.d.d_buf != NULL) 285 data = &scn->rawdata.d; 286 287 if (unlikely (data->d_version == EV_NONE) 288 || unlikely (data->d_version >= EV_NUM)) 289 { 290 __libelf_seterrno (ELF_E_UNKNOWN_VERSION); 291 return -1; 292 } 293 294 if (unlikely (! powerof2 (data->d_align))) 295 { 296 __libelf_seterrno (ELF_E_INVALID_ALIGN); 297 return -1; 298 } 299 300 sh_align = MAX (sh_align, data->d_align); 301 302 if (elf->flags & ELF_F_LAYOUT) 303 { 304 /* The user specified the offset and the size. 305 All we have to do is check whether this block 306 fits in the size specified for the section. */ 307 if (unlikely ((GElf_Word) (data->d_off 308 + data->d_size) 309 > shdr->sh_size)) 310 { 311 __libelf_seterrno (ELF_E_SECTION_TOO_SMALL); 312 return -1; 313 } 314 } 315 else 316 { 317 /* Determine the padding. */ 318 offset = ((offset + data->d_align - 1) 319 & ~(data->d_align - 1)); 320 321 update_if_changed (data->d_off, offset, changed); 322 323 offset += data->d_size; 324 } 325 326 /* Next data block. */ 327 dl = dl->next; 328 } 329 } 330 else 331 /* Get the size of the section from the raw data. If 332 none is available the value is zero. */ 333 offset += scn->rawdata.d.d_size; 334 335 if (elf->flags & ELF_F_LAYOUT) 336 { 337 size = MAX ((GElf_Word) size, 338 (shdr->sh_type != SHT_NOBITS 339 ? shdr->sh_offset + shdr->sh_size : 0)); 340 341 /* The alignment must be a power of two. This is a 342 requirement from the ELF specification. Additionally 343 we test for the alignment of the section being large 344 enough for the largest alignment required by a data 345 block. */ 346 if (unlikely (! powerof2 (shdr->sh_addralign)) 347 || unlikely ((shdr->sh_addralign ?: 1) < sh_align)) 348 { 349 __libelf_seterrno (ELF_E_INVALID_ALIGN); 350 return -1; 351 } 352 } 353 else 354 { 355 /* How much alignment do we need for this section. */ 356 update_if_changed (shdr->sh_addralign, sh_align, 357 scn->shdr_flags); 358 359 size = (size + sh_align - 1) & ~(sh_align - 1); 360 int offset_changed = 0; 361 update_if_changed (shdr->sh_offset, (GElf_Word) size, 362 offset_changed); 363 changed |= offset_changed; 364 365 if (offset_changed && scn->data_list_rear == NULL) 366 { 367 /* The position of the section in the file 368 changed. Create the section data list. */ 369 if (__elf_getdata_rdlock (scn, NULL) == NULL) 370 return -1; 371 } 372 373 /* See whether the section size is correct. */ 374 update_if_changed (shdr->sh_size, (GElf_Word) offset, 375 changed); 376 377 if (shdr->sh_type != SHT_NOBITS) 378 size += offset; 379 380 scn->flags |= changed; 381 } 382 383 /* Check that the section size is actually a multiple of 384 the entry size. */ 385 if (shdr->sh_entsize != 0 && shdr->sh_entsize != 1 386 && (elf->flags & ELF_F_PERMISSIVE) == 0) 387 { 388 /* For compressed sections check the uncompressed size. */ 389 ElfW2(LIBELFBITS,Word) sh_size; 390 if ((shdr->sh_flags & SHF_COMPRESSED) == 0) 391 sh_size = shdr->sh_size; 392 else 393 { 394 ElfW2(LIBELFBITS,Chdr) *chdr; 395 chdr = elfw2(LIBELFBITS,getchdr) (scn); 396 if (unlikely (chdr == NULL)) 397 return -1; 398 sh_size = chdr->ch_size; 399 } 400 401 if (unlikely (sh_size % shdr->sh_entsize != 0)) 402 { 403 __libelf_seterrno (ELF_E_INVALID_SHENTSIZE); 404 return -1; 405 } 406 } 407 } 408 409 assert (list->next == NULL || list->cnt == list->max); 410 411 first = false; 412 } 413 while ((list = list->next) != NULL); 414 415 /* Store section information. */ 416 update_if_changed (ehdr->e_shentsize, 417 elf_typesize (LIBELFBITS, ELF_T_SHDR, 1), ehdr_flags); 418 if (elf->flags & ELF_F_LAYOUT) 419 { 420 /* The user is supposed to fill out e_shoff. Use it and 421 e_shnum (or sh_size of the dummy, first section header) 422 to determine the maximum extend. */ 423 size = MAX ((GElf_Word) size, 424 (ehdr->e_shoff 425 + (elf_typesize (LIBELFBITS, ELF_T_SHDR, shnum)))); 426 } 427 else 428 { 429 /* Align for section header table. 430 431 Yes, we use `sizeof' and not `__alignof__' since we do not 432 want to be surprised by architectures with less strict 433 alignment rules. */ 434 #define SHDR_ALIGN sizeof (ElfW2(LIBELFBITS,Off)) 435 size = (size + SHDR_ALIGN - 1) & ~(SHDR_ALIGN - 1); 436 437 update_if_changed (ehdr->e_shoff, (GElf_Word) size, elf->flags); 438 439 /* Account for the section header size. */ 440 size += elf_typesize (LIBELFBITS, ELF_T_SHDR, shnum); 441 } 442 } 443 444 elf->state.ELFW(elf,LIBELFBITS).ehdr_flags |= ehdr_flags; 445 446 return size; 447 } 448
