1 /*- 2 * Copyright (c) 2006,2008,2010 Joseph Koshy 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS `AS IS' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <assert.h> 28 #include <ctype.h> 29 #include <libelf.h> 30 #include <stdlib.h> 31 #include <string.h> 32 33 #include "_libelf.h" 34 #include "_libelf_ar.h" 35 36 ELFTC_VCSID("$Id: libelf_ar.c 3174 2015-03-27 17:13:41Z emaste $"); 37 38 #define LIBELF_NALLOC_SIZE 16 39 40 /* 41 * `ar' archive handling. 42 * 43 * `ar' archives start with signature `ARMAG'. Each archive member is 44 * preceded by a header containing meta-data for the member. This 45 * header is described in <ar.h> (struct ar_hdr). The header always 46 * starts on an even address. File data is padded with "\n" 47 * characters to keep this invariant. 48 * 49 * Special considerations for `ar' archives: 50 * 51 * There are two variants of the `ar' archive format: traditional BSD 52 * and SVR4. These differ in the way long file names are treated, and 53 * in the layout of the archive symbol table. 54 * 55 * The `ar' header only has space for a 16 character file name. 56 * 57 * In the SVR4 format, file names are terminated with a '/', so this 58 * effectively leaves 15 characters for the actual file name. Longer 59 * file names stored in a separate 'string table' and referenced 60 * indirectly from the name field. The string table itself appears as 61 * an archive member with name "// ". An `indirect' file name in an 62 * `ar' header matches the pattern "/[0-9]*". The digits form a 63 * decimal number that corresponds to a byte offset into the string 64 * table where the actual file name of the object starts. Strings in 65 * the string table are padded to start on even addresses. 66 * 67 * In the BSD format, file names can be upto 16 characters. File 68 * names shorter than 16 characters are padded to 16 characters using 69 * (ASCII) space characters. File names with embedded spaces and file 70 * names longer than 16 characters are stored immediately after the 71 * archive header and the name field set to a special indirect name 72 * matching the pattern "#1/[0-9]+". The digits form a decimal number 73 * that corresponds to the actual length of the file name following 74 * the archive header. The content of the archive member immediately 75 * follows the file name, and the size field of the archive member 76 * holds the sum of the sizes of the member and of the appended file 77 * name. 78 * 79 * Archives may also have a symbol table (see ranlib(1)), mapping 80 * program symbols to object files inside the archive. 81 * 82 * In the SVR4 format, a symbol table uses a file name of "/ " in its 83 * archive header. The symbol table is structured as: 84 * - a 4-byte count of entries stored as a binary value, MSB first 85 * - 'n' 4-byte offsets, stored as binary values, MSB first 86 * - 'n' NUL-terminated strings, for ELF symbol names, stored unpadded. 87 * 88 * In the BSD format, the symbol table uses a file name of "__.SYMDEF". 89 * It is structured as two parts: 90 * - The first part is an array of "ranlib" structures preceded by 91 * the size of the array in bytes. Each "ranlib" structure 92 * describes one symbol. Each structure contains an offset into 93 * the string table for the symbol name, and a file offset into the 94 * archive for the member defining the symbol. 95 * - The second part is a string table containing NUL-terminated 96 * strings, preceded by the size of the string table in bytes. 97 * 98 * If the symbol table and string table are is present in an archive 99 * they must be the very first objects and in that order. 100 */ 101 102 103 /* 104 * Retrieve an archive header descriptor. 105 */ 106 107 Elf_Arhdr * 108 _libelf_ar_gethdr(Elf *e) 109 { 110 Elf *parent; 111 Elf_Arhdr *eh; 112 char *namelen; 113 size_t n, nlen; 114 struct ar_hdr *arh; 115 116 if ((parent = e->e_parent) == NULL) { 117 LIBELF_SET_ERROR(ARGUMENT, 0); 118 return (NULL); 119 } 120 121 assert((e->e_flags & LIBELF_F_AR_HEADER) == 0); 122 123 arh = (struct ar_hdr *) (uintptr_t) e->e_hdr.e_rawhdr; 124 125 assert((uintptr_t) arh >= (uintptr_t) parent->e_rawfile + SARMAG); 126 assert((uintptr_t) arh <= (uintptr_t) parent->e_rawfile + 127 parent->e_rawsize - sizeof(struct ar_hdr)); 128 129 if ((eh = malloc(sizeof(Elf_Arhdr))) == NULL) { 130 LIBELF_SET_ERROR(RESOURCE, 0); 131 return (NULL); 132 } 133 134 e->e_hdr.e_arhdr = eh; 135 e->e_flags |= LIBELF_F_AR_HEADER; 136 137 eh->ar_name = eh->ar_rawname = NULL; 138 139 if ((eh->ar_name = _libelf_ar_get_translated_name(arh, parent)) == 140 NULL) 141 goto error; 142 143 if (_libelf_ar_get_number(arh->ar_uid, sizeof(arh->ar_uid), 10, 144 &n) == 0) 145 goto error; 146 eh->ar_uid = (uid_t) n; 147 148 if (_libelf_ar_get_number(arh->ar_gid, sizeof(arh->ar_gid), 10, 149 &n) == 0) 150 goto error; 151 eh->ar_gid = (gid_t) n; 152 153 if (_libelf_ar_get_number(arh->ar_mode, sizeof(arh->ar_mode), 8, 154 &n) == 0) 155 goto error; 156 eh->ar_mode = (mode_t) n; 157 158 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, 159 &n) == 0) 160 goto error; 161 162 /* 163 * Get the true size of the member if extended naming is being used. 164 */ 165 if (IS_EXTENDED_BSD_NAME(arh->ar_name)) { 166 namelen = arh->ar_name + 167 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE; 168 if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) - 169 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nlen) == 0) 170 goto error; 171 n -= nlen; 172 } 173 174 eh->ar_size = n; 175 176 if ((eh->ar_rawname = _libelf_ar_get_raw_name(arh)) == NULL) 177 goto error; 178 179 eh->ar_flags = 0; 180 181 return (eh); 182 183 error: 184 if (eh) { 185 if (eh->ar_name) 186 free(eh->ar_name); 187 if (eh->ar_rawname) 188 free(eh->ar_rawname); 189 free(eh); 190 } 191 192 e->e_flags &= ~LIBELF_F_AR_HEADER; 193 e->e_hdr.e_rawhdr = (unsigned char *) arh; 194 195 return (NULL); 196 } 197 198 Elf * 199 _libelf_ar_open_member(int fd, Elf_Cmd c, Elf *elf) 200 { 201 Elf *e; 202 off_t next; 203 size_t nsz, sz; 204 struct ar_hdr *arh; 205 char *member, *namelen; 206 207 assert(elf->e_kind == ELF_K_AR); 208 209 next = elf->e_u.e_ar.e_next; 210 211 /* 212 * `next' is only set to zero by elf_next() when the last 213 * member of an archive is processed. 214 */ 215 if (next == (off_t) 0) 216 return (NULL); 217 218 assert((next & 1) == 0); 219 220 arh = (struct ar_hdr *) (elf->e_rawfile + next); 221 222 /* 223 * Retrieve the size of the member. 224 */ 225 if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, 226 &sz) == 0) { 227 LIBELF_SET_ERROR(ARCHIVE, 0); 228 return (NULL); 229 } 230 231 /* 232 * Adjust the size field for members in BSD archives using 233 * extended naming. 234 */ 235 if (IS_EXTENDED_BSD_NAME(arh->ar_name)) { 236 namelen = arh->ar_name + 237 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE; 238 if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) - 239 LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nsz) == 0) { 240 LIBELF_SET_ERROR(ARCHIVE, 0); 241 return (NULL); 242 } 243 244 member = (char *) (arh + 1) + nsz; 245 sz -= nsz; 246 } else 247 member = (char *) (arh + 1); 248 249 250 if ((e = elf_memory(member, sz)) == NULL) 251 return (NULL); 252 253 e->e_fd = fd; 254 e->e_cmd = c; 255 e->e_hdr.e_rawhdr = (unsigned char *) arh; 256 257 elf->e_u.e_ar.e_nchildren++; 258 e->e_parent = elf; 259 260 return (e); 261 } 262 263 /* 264 * A BSD-style ar(1) symbol table has the following layout: 265 * 266 * - A count of bytes used by the following array of 'ranlib' 267 * structures, stored as a 'long'. 268 * - An array of 'ranlib' structures. Each array element is 269 * two 'long's in size. 270 * - A count of bytes used for the following symbol table. 271 * - The symbol table itself. 272 */ 273 274 /* 275 * A helper macro to read in a 'long' value from the archive. 276 * 277 * We use memcpy() since the source pointer may be misaligned with 278 * respect to the natural alignment for a C 'long'. 279 */ 280 #define GET_LONG(P, V)do { \ 281 memcpy(&(V), (P), sizeof(long)); \ 282 (P) += sizeof(long); \ 283 } while (0) 284 285 Elf_Arsym * 286 _libelf_ar_process_bsd_symtab(Elf *e, size_t *count) 287 { 288 Elf_Arsym *symtab, *sym; 289 unsigned int n, nentries; 290 unsigned char *end, *p, *p0, *s, *s0; 291 const size_t entrysize = 2 * sizeof(long); 292 long arraysize, fileoffset, stroffset, strtabsize; 293 294 assert(e != NULL); 295 assert(count != NULL); 296 assert(e->e_u.e_ar.e_symtab == NULL); 297 298 symtab = NULL; 299 300 /* 301 * The BSD symbol table always contains the count fields even 302 * if there are no entries in it. 303 */ 304 if (e->e_u.e_ar.e_rawsymtabsz < 2 * sizeof(long)) 305 goto symtaberror; 306 307 p = p0 = (unsigned char *) e->e_u.e_ar.e_rawsymtab; 308 end = p0 + e->e_u.e_ar.e_rawsymtabsz; 309 310 /* 311 * Retrieve the size of the array of ranlib descriptors and 312 * check it for validity. 313 */ 314 GET_LONG(p, arraysize); 315 316 if (arraysize < 0 || p0 + arraysize >= end || 317 ((size_t) arraysize % entrysize != 0)) 318 goto symtaberror; 319 320 /* 321 * Check the value of the string table size. 322 */ 323 s = p + arraysize; 324 GET_LONG(s, strtabsize); 325 326 s0 = s; /* Start of string table. */ 327 if (strtabsize < 0 || s0 + strtabsize > end) 328 goto symtaberror; 329 330 nentries = (size_t) arraysize / entrysize; 331 332 /* 333 * Allocate space for the returned Elf_Arsym array. 334 */ 335 if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries + 1))) == NULL) { 336 LIBELF_SET_ERROR(RESOURCE, 0); 337 return (NULL); 338 } 339 340 /* Read in symbol table entries. */ 341 for (n = 0, sym = symtab; n < nentries; n++, sym++) { 342 GET_LONG(p, stroffset); 343 GET_LONG(p, fileoffset); 344 345 if (stroffset < 0 || fileoffset < 0 || 346 (size_t) fileoffset >= e->e_rawsize) 347 goto symtaberror; 348 349 s = s0 + stroffset; 350 351 if (s >= end) 352 goto symtaberror; 353 354 sym->as_off = (off_t) fileoffset; 355 sym->as_hash = elf_hash((char *) s); 356 sym->as_name = (char *) s; 357 } 358 359 /* Fill up the sentinel entry. */ 360 sym->as_name = NULL; 361 sym->as_hash = ~0UL; 362 sym->as_off = (off_t) 0; 363 364 /* Remember the processed symbol table. */ 365 e->e_u.e_ar.e_symtab = symtab; 366 367 *count = e->e_u.e_ar.e_symtabsz = nentries + 1; 368 369 return (symtab); 370 371 symtaberror: 372 if (symtab) 373 free(symtab); 374 LIBELF_SET_ERROR(ARCHIVE, 0); 375 return (NULL); 376 } 377 378 /* 379 * An SVR4-style ar(1) symbol table has the following layout: 380 * 381 * - The first 4 bytes are a binary count of the number of entries in the 382 * symbol table, stored MSB-first. 383 * - Then there are 'n' 4-byte binary offsets, also stored MSB first. 384 * - Following this, there are 'n' null-terminated strings. 385 */ 386 387 #define GET_WORD(P, V) do { \ 388 (V) = 0; \ 389 (V) = (P)[0]; (V) <<= 8; \ 390 (V) += (P)[1]; (V) <<= 8; \ 391 (V) += (P)[2]; (V) <<= 8; \ 392 (V) += (P)[3]; \ 393 } while (0) 394 395 #define INTSZ 4 396 397 398 Elf_Arsym * 399 _libelf_ar_process_svr4_symtab(Elf *e, size_t *count) 400 { 401 uint32_t off; 402 size_t n, nentries; 403 Elf_Arsym *symtab, *sym; 404 unsigned char *p, *s, *end; 405 406 assert(e != NULL); 407 assert(count != NULL); 408 assert(e->e_u.e_ar.e_symtab == NULL); 409 410 symtab = NULL; 411 412 if (e->e_u.e_ar.e_rawsymtabsz < INTSZ) 413 goto symtaberror; 414 415 p = (unsigned char *) e->e_u.e_ar.e_rawsymtab; 416 end = p + e->e_u.e_ar.e_rawsymtabsz; 417 418 GET_WORD(p, nentries); 419 p += INTSZ; 420 421 if (nentries == 0 || p + nentries * INTSZ >= end) 422 goto symtaberror; 423 424 /* Allocate space for a nentries + a sentinel. */ 425 if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries+1))) == NULL) { 426 LIBELF_SET_ERROR(RESOURCE, 0); 427 return (NULL); 428 } 429 430 s = p + (nentries * INTSZ); /* start of the string table. */ 431 432 for (n = nentries, sym = symtab; n > 0; n--) { 433 if (s >= end) 434 goto symtaberror; 435 436 GET_WORD(p, off); 437 if (off >= e->e_rawsize) 438 goto symtaberror; 439 440 sym->as_off = (off_t) off; 441 sym->as_hash = elf_hash((char *) s); 442 sym->as_name = (char *) s; 443 444 p += INTSZ; 445 sym++; 446 447 for (; s < end && *s++ != '\0';) /* skip to next string */ 448 ; 449 } 450 451 /* Fill up the sentinel entry. */ 452 sym->as_name = NULL; 453 sym->as_hash = ~0UL; 454 sym->as_off = (off_t) 0; 455 456 *count = e->e_u.e_ar.e_symtabsz = nentries + 1; 457 e->e_u.e_ar.e_symtab = symtab; 458 459 return (symtab); 460 461 symtaberror: 462 if (symtab) 463 free(symtab); 464 LIBELF_SET_ERROR(ARCHIVE, 0); 465 return (NULL); 466 } 467