1 /* 2 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. All advertising materials mentioning features or use of this software 13 * must display the following acknowledgement: 14 * This product includes software developed by Christopher G. Demetriou 15 * for the NetBSD Project. 16 * 4. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 #ifndef lint 33 #if 0 34 __RCSID("$NetBSD: exec_elf32.c,v 1.6 1999/09/20 04:12:16 christos Exp $"); 35 #endif 36 #endif 37 __FBSDID("$FreeBSD$"); 38 39 #ifndef ELFSIZE 40 #define ELFSIZE 32 41 #endif 42 43 #include <sys/types.h> 44 #include <sys/endian.h> 45 #include <sys/stat.h> 46 47 #include <errno.h> 48 #include <limits.h> 49 #include <stddef.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #include "extern.h" 56 57 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 58 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 59 60 #define __ELF_WORD_SIZE ELFSIZE 61 #if (ELFSIZE == 32) 62 #include <sys/elf32.h> 63 #define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 64 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 65 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 66 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 67 #elif (ELFSIZE == 64) 68 #include <sys/elf64.h> 69 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 70 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 71 /* elf64 Elf64_Word are 32 bits */ 72 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 73 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 74 #endif 75 #include <sys/elf_generic.h> 76 77 #define CONCAT(x,y) __CONCAT(x,y) 78 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 79 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 80 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 81 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 82 83 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 84 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 85 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 86 87 struct shlayout { 88 Elf_Shdr *shdr; 89 void *bufp; 90 }; 91 92 static ssize_t 93 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 94 { 95 ssize_t rv; 96 97 if (lseek(fd, off, SEEK_SET) != off) { 98 perror(fn); 99 return -1; 100 } 101 if ((size_t)(rv = read(fd, buf, size)) != size) { 102 fprintf(stderr, "%s: read error: %s\n", fn, 103 rv == -1 ? strerror(errno) : "short read"); 104 return -1; 105 } 106 return size; 107 } 108 109 static ssize_t 110 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 111 { 112 ssize_t rv; 113 114 if (lseek(fd, off, SEEK_SET) != off) { 115 perror(fn); 116 return -1; 117 } 118 if ((size_t)(rv = write(fd, buf, size)) != size) { 119 fprintf(stderr, "%s: write error: %s\n", fn, 120 rv == -1 ? strerror(errno) : "short write"); 121 return -1; 122 } 123 return size; 124 } 125 126 static void * 127 xmalloc(size_t size, const char *fn, const char *use) 128 { 129 void *rv; 130 131 rv = malloc(size); 132 if (rv == NULL) 133 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 134 fn, use); 135 return (rv); 136 } 137 138 static void * 139 xrealloc(void *ptr, size_t size, const char *fn, const char *use) 140 { 141 void *rv; 142 143 rv = realloc(ptr, size); 144 if (rv == NULL) { 145 free(ptr); 146 fprintf(stderr, "%s: out of memory (reallocating for %s)\n", 147 fn, use); 148 } 149 return (rv); 150 } 151 152 int 153 ELFNAMEEND(check)(int fd, const char *fn) 154 { 155 Elf_Ehdr eh; 156 struct stat sb; 157 unsigned char data; 158 159 /* 160 * Check the header to maek sure it's an ELF file (of the 161 * appropriate size). 162 */ 163 if (fstat(fd, &sb) == -1) 164 return 0; 165 if (sb.st_size < (off_t)(sizeof eh)) 166 return 0; 167 if (read(fd, &eh, sizeof eh) != sizeof eh) 168 return 0; 169 170 if (IS_ELF(eh) == 0) 171 return 0; 172 173 data = eh.e_ident[EI_DATA]; 174 175 switch (xe16toh(eh.e_machine)) { 176 case EM_386: break; 177 case EM_ALPHA: break; 178 #ifndef EM_AARCH64 179 #define EM_AARCH64 183 180 #endif 181 case EM_AARCH64: break; 182 #ifndef EM_ARM 183 #define EM_ARM 40 184 #endif 185 case EM_ARM: break; 186 #ifndef EM_MIPS 187 #define EM_MIPS 8 188 #endif 189 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */ 190 #define EM_MIPS_RS4_BE 10 191 #endif 192 case EM_MIPS: break; 193 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 194 #ifndef EM_PPC 195 #define EM_PPC 20 196 #endif 197 case EM_PPC: break; 198 #ifndef EM_PPC64 199 #define EM_PPC64 21 200 #endif 201 case EM_PPC64: break; 202 #ifndef EM_SPARCV9 203 #define EM_SPARCV9 43 204 #endif 205 case EM_SPARCV9: break; 206 #ifndef EM_X86_64 207 #define EM_X86_64 62 208 #endif 209 case EM_X86_64: break; 210 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 211 212 default: 213 return 0; 214 } 215 216 return 1; 217 } 218 219 /* 220 * This function 'hides' (some of) ELF executable file's symbols. 221 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 222 * Symbols in the global keep list, or which are marked as being undefined, 223 * are left alone. 224 * 225 * An old version of this code shuffled various tables around, turning 226 * global symbols to be hidden into local symbols. That lost on the 227 * mips, because CALL16 relocs must reference global symbols, and, if 228 * those symbols were being hidden, they were no longer global. 229 * 230 * The new renaming behaviour doesn't take global symbols out of the 231 * namespace. However, it's ... unlikely that there will ever be 232 * any collisions in practice because of the new method. 233 */ 234 int 235 ELFNAMEEND(hide)(int fd, const char *fn) 236 { 237 Elf_Ehdr ehdr; 238 struct shlayout *layoutp = NULL; 239 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr; 240 Elf_Shdr shdrshdr; 241 Elf_Sym *symtabp = NULL; 242 char *shstrtabp = NULL, *strtabp = NULL; 243 Elf_Size nsyms, ewi; 244 Elf_Off off; 245 ssize_t shdrsize; 246 int rv, i, weird, l, m, r, strtabidx; 247 size_t nstrtab_size, nstrtab_nextoff, fn_size, size; 248 char *nstrtabp = NULL; 249 unsigned char data; 250 const char *weirdreason = NULL; 251 void *buf; 252 Elf_Half shnum; 253 254 rv = 0; 255 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 256 goto bad; 257 258 data = ehdr.e_ident[EI_DATA]; 259 shnum = xe16toh(ehdr.e_shnum); 260 261 shdrsize = shnum * xe16toh(ehdr.e_shentsize); 262 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 263 goto bad; 264 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 265 shdrsize) 266 goto bad; 267 268 symtabshdr = strtabshdr = shstrtabshdr = NULL; 269 weird = 0; 270 for (i = 0; i < shnum; i++) { 271 switch (xe32toh(shdrp[i].sh_type)) { 272 case SHT_SYMTAB: 273 if (symtabshdr != NULL) { 274 weird = 1; 275 weirdreason = "multiple symbol tables"; 276 } 277 symtabshdr = &shdrp[i]; 278 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 279 break; 280 case SHT_STRTAB: 281 if (i == xe16toh(ehdr.e_shstrndx)) 282 shstrtabshdr = &shdrp[i]; 283 break; 284 } 285 } 286 if (symtabshdr == NULL) 287 goto out; 288 if (strtabshdr == NULL) { 289 weird = 1; 290 weirdreason = "string table does not exist"; 291 } 292 if (shstrtabshdr == NULL) { 293 weird = 1; 294 weirdreason = "section header string table does not exist"; 295 } 296 if (weirdreason == NULL) 297 weirdreason = "unsupported"; 298 if (weird) { 299 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 300 goto bad; 301 } 302 303 /* 304 * sort section layout table by offset 305 */ 306 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout), 307 fn, "layout table"); 308 if (layoutp == NULL) 309 goto bad; 310 311 /* add a pseudo entry to represent the section header table */ 312 shdrshdr.sh_offset = ehdr.e_shoff; 313 shdrshdr.sh_size = htoxew(shdrsize); 314 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8); 315 layoutp[shnum].shdr = &shdrshdr; 316 317 /* insert and sort normal section headers */ 318 for (i = shnum; i-- != 0;) { 319 l = i + 1; 320 r = shnum; 321 while (l <= r) { 322 m = ( l + r) / 2; 323 if (xewtoh(shdrp[i].sh_offset) > 324 xewtoh(layoutp[m].shdr->sh_offset)) 325 l = m + 1; 326 else 327 r = m - 1; 328 } 329 330 if (r != i) { 331 memmove(&layoutp[i], &layoutp[i + 1], 332 sizeof(struct shlayout) * (r - i)); 333 } 334 335 layoutp[r].shdr = &shdrp[i]; 336 layoutp[r].bufp = NULL; 337 } 338 ++shnum; 339 340 /* 341 * load up everything we need 342 */ 343 344 /* load section string table for debug use */ 345 if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn, 346 "section string table")) == NULL) 347 goto bad; 348 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset), 349 xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size)) 350 goto bad; 351 352 /* we need symtab, strtab, and everything behind strtab */ 353 strtabidx = INT_MAX; 354 for (i = 0; i < shnum; i++) { 355 if (layoutp[i].shdr == &shdrshdr) { 356 /* not load section header again */ 357 layoutp[i].bufp = shdrp; 358 continue; 359 } 360 if (layoutp[i].shdr == shstrtabshdr) { 361 /* not load section string table again */ 362 layoutp[i].bufp = shstrtabp; 363 continue; 364 } 365 366 if (layoutp[i].shdr == strtabshdr) 367 strtabidx = i; 368 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) { 369 off = xewtoh(layoutp[i].shdr->sh_offset); 370 size = xewtoh(layoutp[i].shdr->sh_size); 371 layoutp[i].bufp = xmalloc(size, fn, 372 shstrtabp + xewtoh(layoutp[i].shdr->sh_name)); 373 if (layoutp[i].bufp == NULL) 374 goto bad; 375 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) != 376 size) 377 goto bad; 378 379 /* set symbol table and string table */ 380 if (layoutp[i].shdr == symtabshdr) 381 symtabp = layoutp[i].bufp; 382 else if (layoutp[i].shdr == strtabshdr) 383 strtabp = layoutp[i].bufp; 384 } 385 } 386 387 nstrtab_size = 256; 388 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 389 if (nstrtabp == NULL) 390 goto bad; 391 nstrtab_nextoff = 0; 392 393 fn_size = strlen(fn); 394 395 /* Prepare data structures for symbol movement. */ 396 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 397 398 /* move symbols, making them local */ 399 for (ewi = 0; ewi < nsyms; ewi++) { 400 Elf_Sym *sp = &symtabp[ewi]; 401 const char *symname = strtabp + xe32toh(sp->st_name); 402 size_t newent_len; 403 /* 404 * make sure there's size for the next entry, even if it's 405 * as large as it can be. 406 * 407 * "_$$hide$$ <filename> <symname><NUL>" -> 408 * 9 + 3 + sizes of fn and sym name 409 */ 410 while ((nstrtab_size - nstrtab_nextoff) < 411 strlen(symname) + fn_size + 12) { 412 nstrtab_size *= 2; 413 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 414 "new string table"); 415 if (nstrtabp == NULL) 416 goto bad; 417 } 418 419 sp->st_name = htowew(nstrtab_nextoff); 420 421 /* if it's a keeper or is undefined, don't rename it. */ 422 if (in_keep_list(symname) || 423 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 424 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 425 "%s", symname) + 1; 426 } else { 427 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 428 "_$$hide$$ %s %s", fn, symname) + 1; 429 } 430 nstrtab_nextoff += newent_len; 431 } 432 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 433 434 /* 435 * update section header table in ascending order of offset 436 */ 437 for (i = strtabidx + 1; i < shnum; i++) { 438 Elf_Off off, align; 439 off = xewtoh(layoutp[i - 1].shdr->sh_offset) + 440 xewtoh(layoutp[i - 1].shdr->sh_size); 441 align = xewtoh(layoutp[i].shdr->sh_addralign); 442 off = (off + (align - 1)) & ~(align - 1); 443 layoutp[i].shdr->sh_offset = htoxew(off); 444 } 445 446 /* 447 * write data to the file in descending order of offset 448 */ 449 for (i = shnum; i-- != 0;) { 450 if (layoutp[i].shdr == strtabshdr) { 451 /* new string table */ 452 buf = nstrtabp; 453 } else 454 buf = layoutp[i].bufp; 455 456 if (layoutp[i].shdr == &shdrshdr || 457 layoutp[i].shdr == symtabshdr || i >= strtabidx) { 458 if (buf == NULL) 459 goto bad; 460 461 /* 462 * update the offset of section header table in elf 463 * header if needed. 464 */ 465 if (layoutp[i].shdr == &shdrshdr && 466 ehdr.e_shoff != shdrshdr.sh_offset) { 467 ehdr.e_shoff = shdrshdr.sh_offset; 468 off = offsetof(Elf_Ehdr, e_shoff); 469 size = sizeof(Elf_Off); 470 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size, 471 fn) != size) 472 goto bad; 473 } 474 475 off = xewtoh(layoutp[i].shdr->sh_offset); 476 size = xewtoh(layoutp[i].shdr->sh_size); 477 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size) 478 goto bad; 479 } 480 } 481 482 out: 483 if (layoutp != NULL) { 484 for (i = 0; i < shnum; i++) { 485 if (layoutp[i].bufp != NULL) 486 free(layoutp[i].bufp); 487 } 488 free(layoutp); 489 } 490 free(nstrtabp); 491 return (rv); 492 493 bad: 494 rv = 1; 495 goto out; 496 } 497 498 #endif /* include this size of ELF */ 499