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 #ifdef __x86_64__ 32 #define ELFSIZE 64 33 #endif 34 35 #include <sys/types.h> 36 #include <sys/endian.h> 37 #include <sys/stat.h> 38 39 #include <errno.h> 40 #include <limits.h> 41 #include <stddef.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 47 #include "extern.h" 48 49 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 50 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 51 52 #define __ELF_WORD_SIZE ELFSIZE 53 #if (ELFSIZE == 32) 54 #include <sys/elf32.h> 55 #define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 56 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 57 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 58 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 59 #elif (ELFSIZE == 64) 60 #include <sys/elf64.h> 61 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 62 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 63 /* elf64 Elf64_Word are 32 bits */ 64 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 65 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 66 #endif 67 #include <sys/elf_generic.h> 68 69 #define CONCAT(x,y) __CONCAT(x,y) 70 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 71 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 72 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 73 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 74 75 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 76 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 77 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 78 79 struct shlayout { 80 Elf_Shdr *shdr; 81 void *bufp; 82 }; 83 84 static ssize_t 85 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 86 { 87 ssize_t rv; 88 89 if (lseek(fd, off, SEEK_SET) != off) { 90 perror(fn); 91 return -1; 92 } 93 if ((size_t)(rv = read(fd, buf, size)) != size) { 94 fprintf(stderr, "%s: read error: %s\n", fn, 95 rv == -1 ? strerror(errno) : "short read"); 96 return -1; 97 } 98 return size; 99 } 100 101 static ssize_t 102 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 103 { 104 ssize_t rv; 105 106 if (lseek(fd, off, SEEK_SET) != off) { 107 perror(fn); 108 return -1; 109 } 110 if ((size_t)(rv = write(fd, buf, size)) != size) { 111 fprintf(stderr, "%s: write error: %s\n", fn, 112 rv == -1 ? strerror(errno) : "short write"); 113 return -1; 114 } 115 return size; 116 } 117 118 static void * 119 xmalloc(size_t size, const char *fn, const char *use) 120 { 121 void *rv; 122 123 rv = malloc(size); 124 if (rv == NULL) 125 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 126 fn, use); 127 return (rv); 128 } 129 130 static void * 131 xrealloc(void *ptr, size_t size, const char *fn, const char *use) 132 { 133 void *rv; 134 135 rv = realloc(ptr, size); 136 if (rv == NULL) { 137 free(ptr); 138 fprintf(stderr, "%s: out of memory (reallocating for %s)\n", 139 fn, use); 140 } 141 return (rv); 142 } 143 144 int 145 ELFNAMEEND(check)(int fd, const char *fn) 146 { 147 Elf_Ehdr eh; 148 struct stat sb; 149 unsigned char data; 150 151 /* 152 * Check the header to maek sure it's an ELF file (of the 153 * appropriate size). 154 */ 155 if (fstat(fd, &sb) == -1) 156 return 0; 157 if (sb.st_size < (off_t)(sizeof eh)) 158 return 0; 159 if (read(fd, &eh, sizeof eh) != sizeof eh) 160 return 0; 161 162 if (IS_ELF(eh) == 0) 163 return 0; 164 165 data = eh.e_ident[EI_DATA]; 166 167 switch (xe16toh(eh.e_machine)) { 168 case EM_386: break; 169 case EM_ALPHA: break; 170 #ifndef EM_AARCH64 171 #define EM_AARCH64 183 172 #endif 173 case EM_AARCH64: break; 174 #ifndef EM_ARM 175 #define EM_ARM 40 176 #endif 177 case EM_ARM: break; 178 #ifndef EM_MIPS 179 #define EM_MIPS 8 180 #endif 181 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */ 182 #define EM_MIPS_RS4_BE 10 183 #endif 184 case EM_MIPS: break; 185 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 186 #ifndef EM_PPC 187 #define EM_PPC 20 188 #endif 189 case EM_PPC: break; 190 #ifndef EM_PPC64 191 #define EM_PPC64 21 192 #endif 193 case EM_PPC64: break; 194 #ifndef EM_SPARCV9 195 #define EM_SPARCV9 43 196 #endif 197 case EM_SPARCV9: break; 198 #ifndef EM_X86_64 199 #define EM_X86_64 62 200 #endif 201 case EM_X86_64: break; 202 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 203 204 default: 205 return 0; 206 } 207 208 return 1; 209 } 210 211 /* 212 * This function 'hides' (some of) ELF executable file's symbols. 213 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 214 * Symbols in the global keep list, or which are marked as being undefined, 215 * are left alone. 216 * 217 * An old version of this code shuffled various tables around, turning 218 * global symbols to be hidden into local symbols. That lost on the 219 * mips, because CALL16 relocs must reference global symbols, and, if 220 * those symbols were being hidden, they were no longer global. 221 * 222 * The new renaming behaviour doesn't take global symbols out of the 223 * namespace. However, it's ... unlikely that there will ever be 224 * any collisions in practice because of the new method. 225 */ 226 int 227 ELFNAMEEND(hide)(int fd, const char *fn) 228 { 229 Elf_Ehdr ehdr; 230 struct shlayout *layoutp = NULL; 231 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr; 232 Elf_Shdr shdrshdr; 233 Elf_Sym *symtabp = NULL; 234 char *shstrtabp = NULL, *strtabp = NULL; 235 Elf_Size nsyms, ewi; 236 Elf_Off off; 237 ssize_t shdrsize; 238 int rv, i, weird, l, m, r, strtabidx; 239 size_t nstrtab_size, nstrtab_nextoff, fn_size, size; 240 char *nstrtabp = NULL; 241 unsigned char data; 242 const char *weirdreason = NULL; 243 void *buf; 244 Elf_Half shnum; 245 246 rv = 0; 247 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 248 goto bad; 249 250 data = ehdr.e_ident[EI_DATA]; 251 shnum = xe16toh(ehdr.e_shnum); 252 253 shdrsize = shnum * xe16toh(ehdr.e_shentsize); 254 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 255 goto bad; 256 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 257 shdrsize) 258 goto bad; 259 260 symtabshdr = strtabshdr = shstrtabshdr = NULL; 261 weird = 0; 262 for (i = 0; i < shnum; i++) { 263 switch (xe32toh(shdrp[i].sh_type)) { 264 case SHT_SYMTAB: 265 if (symtabshdr != NULL) { 266 weird = 1; 267 weirdreason = "multiple symbol tables"; 268 } 269 symtabshdr = &shdrp[i]; 270 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 271 break; 272 case SHT_STRTAB: 273 if (i == xe16toh(ehdr.e_shstrndx)) 274 shstrtabshdr = &shdrp[i]; 275 break; 276 } 277 } 278 if (symtabshdr == NULL) 279 goto out; 280 if (strtabshdr == NULL) { 281 weird = 1; 282 weirdreason = "string table does not exist"; 283 } 284 if (shstrtabshdr == NULL) { 285 weird = 1; 286 weirdreason = "section header string table does not exist"; 287 } 288 if (weirdreason == NULL) 289 weirdreason = "unsupported"; 290 if (weird) { 291 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 292 goto bad; 293 } 294 295 /* 296 * sort section layout table by offset 297 */ 298 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout), 299 fn, "layout table"); 300 if (layoutp == NULL) 301 goto bad; 302 303 /* add a pseudo entry to represent the section header table */ 304 shdrshdr.sh_offset = ehdr.e_shoff; 305 shdrshdr.sh_size = htoxew(shdrsize); 306 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8); 307 layoutp[shnum].shdr = &shdrshdr; 308 309 /* insert and sort normal section headers */ 310 for (i = shnum; i-- != 0;) { 311 l = i + 1; 312 r = shnum; 313 while (l <= r) { 314 m = ( l + r) / 2; 315 if (xewtoh(shdrp[i].sh_offset) > 316 xewtoh(layoutp[m].shdr->sh_offset)) 317 l = m + 1; 318 else 319 r = m - 1; 320 } 321 322 if (r != i) { 323 memmove(&layoutp[i], &layoutp[i + 1], 324 sizeof(struct shlayout) * (r - i)); 325 } 326 327 layoutp[r].shdr = &shdrp[i]; 328 layoutp[r].bufp = NULL; 329 } 330 ++shnum; 331 332 /* 333 * load up everything we need 334 */ 335 336 /* load section string table for debug use */ 337 if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn, 338 "section string table")) == NULL) 339 goto bad; 340 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset), 341 xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size)) 342 goto bad; 343 344 /* we need symtab, strtab, and everything behind strtab */ 345 strtabidx = INT_MAX; 346 for (i = 0; i < shnum; i++) { 347 if (layoutp[i].shdr == &shdrshdr) { 348 /* not load section header again */ 349 layoutp[i].bufp = shdrp; 350 continue; 351 } 352 if (layoutp[i].shdr == shstrtabshdr) { 353 /* not load section string table again */ 354 layoutp[i].bufp = shstrtabp; 355 continue; 356 } 357 358 if (layoutp[i].shdr == strtabshdr) 359 strtabidx = i; 360 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) { 361 off = xewtoh(layoutp[i].shdr->sh_offset); 362 size = xewtoh(layoutp[i].shdr->sh_size); 363 layoutp[i].bufp = xmalloc(size, fn, 364 shstrtabp + xewtoh(layoutp[i].shdr->sh_name)); 365 if (layoutp[i].bufp == NULL) 366 goto bad; 367 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) != 368 size) 369 goto bad; 370 371 /* set symbol table and string table */ 372 if (layoutp[i].shdr == symtabshdr) 373 symtabp = layoutp[i].bufp; 374 else if (layoutp[i].shdr == strtabshdr) 375 strtabp = layoutp[i].bufp; 376 } 377 } 378 379 nstrtab_size = 256; 380 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 381 if (nstrtabp == NULL) 382 goto bad; 383 nstrtab_nextoff = 0; 384 385 fn_size = strlen(fn); 386 387 /* Prepare data structures for symbol movement. */ 388 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 389 390 /* move symbols, making them local */ 391 for (ewi = 0; ewi < nsyms; ewi++) { 392 Elf_Sym *sp = &symtabp[ewi]; 393 const char *symname = strtabp + xe32toh(sp->st_name); 394 size_t newent_len; 395 /* 396 * make sure there's size for the next entry, even if it's 397 * as large as it can be. 398 * 399 * "_$$hide$$ <filename> <symname><NUL>" -> 400 * 9 + 3 + sizes of fn and sym name 401 */ 402 while ((nstrtab_size - nstrtab_nextoff) < 403 strlen(symname) + fn_size + 12) { 404 nstrtab_size *= 2; 405 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 406 "new string table"); 407 if (nstrtabp == NULL) 408 goto bad; 409 } 410 411 sp->st_name = htowew(nstrtab_nextoff); 412 413 /* if it's a keeper or is undefined, don't rename it. */ 414 if (in_keep_list(symname) || 415 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 416 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 417 "%s", symname) + 1; 418 } else { 419 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 420 "_$$hide$$ %s %s", fn, symname) + 1; 421 } 422 nstrtab_nextoff += newent_len; 423 } 424 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 425 426 /* 427 * update section header table in ascending order of offset 428 */ 429 for (i = strtabidx + 1; i < shnum; i++) { 430 Elf_Off off, align; 431 off = xewtoh(layoutp[i - 1].shdr->sh_offset) + 432 xewtoh(layoutp[i - 1].shdr->sh_size); 433 align = xewtoh(layoutp[i].shdr->sh_addralign); 434 off = (off + (align - 1)) & ~(align - 1); 435 layoutp[i].shdr->sh_offset = htoxew(off); 436 } 437 438 /* 439 * write data to the file in descending order of offset 440 */ 441 for (i = shnum; i-- != 0;) { 442 if (layoutp[i].shdr == strtabshdr) { 443 /* new string table */ 444 buf = nstrtabp; 445 } else 446 buf = layoutp[i].bufp; 447 448 if (layoutp[i].shdr == &shdrshdr || 449 layoutp[i].shdr == symtabshdr || i >= strtabidx) { 450 if (buf == NULL) 451 goto bad; 452 453 /* 454 * update the offset of section header table in elf 455 * header if needed. 456 */ 457 if (layoutp[i].shdr == &shdrshdr && 458 ehdr.e_shoff != shdrshdr.sh_offset) { 459 ehdr.e_shoff = shdrshdr.sh_offset; 460 off = offsetof(Elf_Ehdr, e_shoff); 461 size = sizeof(Elf_Off); 462 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size, 463 fn) != size) 464 goto bad; 465 } 466 467 off = xewtoh(layoutp[i].shdr->sh_offset); 468 size = xewtoh(layoutp[i].shdr->sh_size); 469 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size) 470 goto bad; 471 } 472 } 473 474 out: 475 if (layoutp != NULL) { 476 for (i = 0; i < shnum; i++) { 477 if (layoutp[i].bufp != NULL) 478 free(layoutp[i].bufp); 479 } 480 free(layoutp); 481 } 482 free(nstrtabp); 483 return (rv); 484 485 bad: 486 rv = 1; 487 goto out; 488 } 489 490 #endif /* include this size of ELF */ 491