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