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