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_ELF64) && (ELFSIZE == 64)) 50 51 #define __ELF_WORD_SIZE ELFSIZE 52 #if (ELFSIZE == 64) 53 #include <sys/elf64.h> 54 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 55 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 56 /* elf64 Elf64_Word are 32 bits */ 57 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 58 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 59 #endif 60 #include <sys/elf_generic.h> 61 62 #define CONCAT(x,y) __CONCAT(x,y) 63 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 64 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 65 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 66 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 67 68 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 69 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 70 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 71 72 struct shlayout { 73 Elf_Shdr *shdr; 74 void *bufp; 75 }; 76 77 static ssize_t 78 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 79 { 80 ssize_t rv; 81 82 if (lseek(fd, off, SEEK_SET) != off) { 83 perror(fn); 84 return -1; 85 } 86 if ((size_t)(rv = read(fd, buf, size)) != size) { 87 fprintf(stderr, "%s: read error: %s\n", fn, 88 rv == -1 ? strerror(errno) : "short read"); 89 return -1; 90 } 91 return size; 92 } 93 94 static ssize_t 95 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 96 { 97 ssize_t rv; 98 99 if (lseek(fd, off, SEEK_SET) != off) { 100 perror(fn); 101 return -1; 102 } 103 if ((size_t)(rv = write(fd, buf, size)) != size) { 104 fprintf(stderr, "%s: write error: %s\n", fn, 105 rv == -1 ? strerror(errno) : "short write"); 106 return -1; 107 } 108 return size; 109 } 110 111 static void * 112 xmalloc(size_t size, const char *fn, const char *use) 113 { 114 void *rv; 115 116 rv = malloc(size); 117 if (rv == NULL) 118 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 119 fn, use); 120 return (rv); 121 } 122 123 static void * 124 xrealloc(void *ptr, size_t size, const char *fn, const char *use) 125 { 126 void *rv; 127 128 rv = realloc(ptr, size); 129 if (rv == NULL) { 130 free(ptr); 131 fprintf(stderr, "%s: out of memory (reallocating for %s)\n", 132 fn, use); 133 } 134 return (rv); 135 } 136 137 int 138 ELFNAMEEND(check)(int fd, const char *fn) 139 { 140 Elf_Ehdr eh; 141 struct stat sb; 142 unsigned char data; 143 144 /* 145 * Check the header to maek sure it's an ELF file (of the 146 * appropriate size). 147 */ 148 if (fstat(fd, &sb) == -1) 149 return 0; 150 if (sb.st_size < (off_t)(sizeof eh)) 151 return 0; 152 if (read(fd, &eh, sizeof eh) != sizeof eh) 153 return 0; 154 155 if (IS_ELF(eh) == 0) 156 return 0; 157 158 data = eh.e_ident[EI_DATA]; 159 160 switch (xe16toh(eh.e_machine)) { 161 case EM_386: break; 162 case EM_ALPHA: break; 163 #ifndef EM_AARCH64 164 #define EM_AARCH64 183 165 #endif 166 case EM_AARCH64: break; 167 #ifndef EM_ARM 168 #define EM_ARM 40 169 #endif 170 case EM_ARM: break; 171 #ifndef EM_MIPS 172 #define EM_MIPS 8 173 #endif 174 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */ 175 #define EM_MIPS_RS4_BE 10 176 #endif 177 case EM_MIPS: break; 178 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 179 #ifndef EM_PPC 180 #define EM_PPC 20 181 #endif 182 case EM_PPC: break; 183 #ifndef EM_PPC64 184 #define EM_PPC64 21 185 #endif 186 case EM_PPC64: break; 187 #ifndef EM_SPARCV9 188 #define EM_SPARCV9 43 189 #endif 190 case EM_SPARCV9: break; 191 #ifndef EM_X86_64 192 #define EM_X86_64 62 193 #endif 194 case EM_X86_64: break; 195 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 196 197 default: 198 return 0; 199 } 200 201 return 1; 202 } 203 204 /* 205 * This function 'hides' (some of) ELF executable file's symbols. 206 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 207 * Symbols in the global keep list, or which are marked as being undefined, 208 * are left alone. 209 * 210 * An old version of this code shuffled various tables around, turning 211 * global symbols to be hidden into local symbols. That lost on the 212 * mips, because CALL16 relocs must reference global symbols, and, if 213 * those symbols were being hidden, they were no longer global. 214 * 215 * The new renaming behaviour doesn't take global symbols out of the 216 * namespace. However, it's ... unlikely that there will ever be 217 * any collisions in practice because of the new method. 218 */ 219 int 220 ELFNAMEEND(hide)(int fd, const char *fn) 221 { 222 Elf_Ehdr ehdr; 223 struct shlayout *layoutp = NULL; 224 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr; 225 Elf_Shdr shdrshdr; 226 Elf_Sym *symtabp = NULL; 227 char *shstrtabp = NULL, *strtabp = NULL; 228 Elf_Size nsyms, ewi; 229 Elf_Off off; 230 ssize_t shdrsize; 231 int rv, i, weird, l, m, r, strtabidx; 232 size_t nstrtab_size, nstrtab_nextoff, fn_size, size; 233 char *nstrtabp = NULL; 234 unsigned char data; 235 const char *weirdreason = NULL; 236 void *buf; 237 Elf_Half shnum; 238 239 rv = 0; 240 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 241 goto bad; 242 243 data = ehdr.e_ident[EI_DATA]; 244 shnum = xe16toh(ehdr.e_shnum); 245 246 shdrsize = shnum * xe16toh(ehdr.e_shentsize); 247 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 248 goto bad; 249 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 250 shdrsize) 251 goto bad; 252 253 symtabshdr = strtabshdr = shstrtabshdr = NULL; 254 weird = 0; 255 for (i = 0; i < shnum; i++) { 256 switch (xe32toh(shdrp[i].sh_type)) { 257 case SHT_SYMTAB: 258 if (symtabshdr != NULL) { 259 weird = 1; 260 weirdreason = "multiple symbol tables"; 261 } 262 symtabshdr = &shdrp[i]; 263 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 264 break; 265 case SHT_STRTAB: 266 if (i == xe16toh(ehdr.e_shstrndx)) 267 shstrtabshdr = &shdrp[i]; 268 break; 269 } 270 } 271 if (symtabshdr == NULL) 272 goto out; 273 if (strtabshdr == NULL) { 274 weird = 1; 275 weirdreason = "string table does not exist"; 276 } 277 if (shstrtabshdr == NULL) { 278 weird = 1; 279 weirdreason = "section header string table does not exist"; 280 } 281 if (weirdreason == NULL) 282 weirdreason = "unsupported"; 283 if (weird) { 284 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 285 goto bad; 286 } 287 288 /* 289 * sort section layout table by offset 290 */ 291 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout), 292 fn, "layout table"); 293 if (layoutp == NULL) 294 goto bad; 295 296 /* add a pseudo entry to represent the section header table */ 297 shdrshdr.sh_offset = ehdr.e_shoff; 298 shdrshdr.sh_size = htoxew(shdrsize); 299 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8); 300 layoutp[shnum].shdr = &shdrshdr; 301 302 /* insert and sort normal section headers */ 303 for (i = shnum; i-- != 0;) { 304 l = i + 1; 305 r = shnum; 306 while (l <= r) { 307 m = ( l + r) / 2; 308 if (xewtoh(shdrp[i].sh_offset) > 309 xewtoh(layoutp[m].shdr->sh_offset)) 310 l = m + 1; 311 else 312 r = m - 1; 313 } 314 315 if (r != i) { 316 memmove(&layoutp[i], &layoutp[i + 1], 317 sizeof(struct shlayout) * (r - i)); 318 } 319 320 layoutp[r].shdr = &shdrp[i]; 321 layoutp[r].bufp = NULL; 322 } 323 ++shnum; 324 325 /* 326 * load up everything we need 327 */ 328 329 /* load section string table for debug use */ 330 if ((shstrtabp = xmalloc(xewtoh(shstrtabshdr->sh_size), fn, 331 "section string table")) == NULL) 332 goto bad; 333 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset), 334 xewtoh(shstrtabshdr->sh_size), fn) != xewtoh(shstrtabshdr->sh_size)) 335 goto bad; 336 337 /* we need symtab, strtab, and everything behind strtab */ 338 strtabidx = INT_MAX; 339 for (i = 0; i < shnum; i++) { 340 if (layoutp[i].shdr == &shdrshdr) { 341 /* not load section header again */ 342 layoutp[i].bufp = shdrp; 343 continue; 344 } 345 if (layoutp[i].shdr == shstrtabshdr) { 346 /* not load section string table again */ 347 layoutp[i].bufp = shstrtabp; 348 continue; 349 } 350 351 if (layoutp[i].shdr == strtabshdr) 352 strtabidx = i; 353 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) { 354 off = xewtoh(layoutp[i].shdr->sh_offset); 355 size = xewtoh(layoutp[i].shdr->sh_size); 356 layoutp[i].bufp = xmalloc(size, fn, 357 shstrtabp + xewtoh(layoutp[i].shdr->sh_name)); 358 if (layoutp[i].bufp == NULL) 359 goto bad; 360 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) != 361 size) 362 goto bad; 363 364 /* set symbol table and string table */ 365 if (layoutp[i].shdr == symtabshdr) 366 symtabp = layoutp[i].bufp; 367 else if (layoutp[i].shdr == strtabshdr) 368 strtabp = layoutp[i].bufp; 369 } 370 } 371 372 nstrtab_size = 256; 373 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 374 if (nstrtabp == NULL) 375 goto bad; 376 nstrtab_nextoff = 0; 377 378 fn_size = strlen(fn); 379 380 /* Prepare data structures for symbol movement. */ 381 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 382 383 /* move symbols, making them local */ 384 for (ewi = 0; ewi < nsyms; ewi++) { 385 Elf_Sym *sp = &symtabp[ewi]; 386 const char *symname = strtabp + xe32toh(sp->st_name); 387 size_t newent_len; 388 /* 389 * make sure there's size for the next entry, even if it's 390 * as large as it can be. 391 * 392 * "_$$hide$$ <filename> <symname><NUL>" -> 393 * 9 + 3 + sizes of fn and sym name 394 */ 395 while ((nstrtab_size - nstrtab_nextoff) < 396 strlen(symname) + fn_size + 12) { 397 nstrtab_size *= 2; 398 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 399 "new string table"); 400 if (nstrtabp == NULL) 401 goto bad; 402 } 403 404 sp->st_name = htowew(nstrtab_nextoff); 405 406 /* if it's a keeper or is undefined, don't rename it. */ 407 if (in_keep_list(symname) || 408 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 409 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 410 "%s", symname) + 1; 411 } else { 412 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 413 "_$$hide$$ %s %s", fn, symname) + 1; 414 } 415 nstrtab_nextoff += newent_len; 416 } 417 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 418 419 /* 420 * update section header table in ascending order of offset 421 */ 422 for (i = strtabidx + 1; i < shnum; i++) { 423 Elf_Off off, align; 424 off = xewtoh(layoutp[i - 1].shdr->sh_offset) + 425 xewtoh(layoutp[i - 1].shdr->sh_size); 426 align = xewtoh(layoutp[i].shdr->sh_addralign); 427 off = (off + (align - 1)) & ~(align - 1); 428 layoutp[i].shdr->sh_offset = htoxew(off); 429 } 430 431 /* 432 * write data to the file in descending order of offset 433 */ 434 for (i = shnum; i-- != 0;) { 435 if (layoutp[i].shdr == strtabshdr) { 436 /* new string table */ 437 buf = nstrtabp; 438 } else 439 buf = layoutp[i].bufp; 440 441 if (layoutp[i].shdr == &shdrshdr || 442 layoutp[i].shdr == symtabshdr || i >= strtabidx) { 443 if (buf == NULL) 444 goto bad; 445 446 /* 447 * update the offset of section header table in elf 448 * header if needed. 449 */ 450 if (layoutp[i].shdr == &shdrshdr && 451 ehdr.e_shoff != shdrshdr.sh_offset) { 452 ehdr.e_shoff = shdrshdr.sh_offset; 453 off = offsetof(Elf_Ehdr, e_shoff); 454 size = sizeof(Elf_Off); 455 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size, 456 fn) != size) 457 goto bad; 458 } 459 460 off = xewtoh(layoutp[i].shdr->sh_offset); 461 size = xewtoh(layoutp[i].shdr->sh_size); 462 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size) 463 goto bad; 464 } 465 } 466 467 out: 468 if (layoutp != NULL) { 469 for (i = 0; i < shnum; i++) { 470 if (layoutp[i].bufp != NULL) 471 free(layoutp[i].bufp); 472 } 473 free(layoutp); 474 } 475 free(nstrtabp); 476 return (rv); 477 478 bad: 479 rv = 1; 480 goto out; 481 } 482 483 #endif /* include this size of ELF */ 484