exec_elf32.c revision 292421
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: stable/10/usr.sbin/crunch/crunchide/exec_elf32.c 292421 2015-12-18 01:44:03Z emaste $"); 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 87struct shlayout { 88 Elf_Shdr *shdr; 89 void *bufp; 90}; 91 92static ssize_t 93xreadatoff(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 109static ssize_t 110xwriteatoff(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 126static void * 127xmalloc(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 138static void * 139xrealloc(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 152int 153ELFNAMEEND(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 case EM_ARM: break; 183 case EM_MIPS: break; 184 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 185 case EM_PPC: break; 186 case EM_PPC64: break; 187#ifndef EM_RISCV 188#define EM_RISCV 243 189#endif 190 case EM_RISCV: break; 191 case EM_SPARCV9: break; 192 case EM_X86_64: break; 193/* ELFDEFNNAME(MACHDEP_ID_CASES) */ 194 195 default: 196 return 0; 197 } 198 199 return 1; 200} 201 202/* 203 * This function 'hides' (some of) ELF executable file's symbols. 204 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 205 * Symbols in the global keep list, or which are marked as being undefined, 206 * are left alone. 207 * 208 * An old version of this code shuffled various tables around, turning 209 * global symbols to be hidden into local symbols. That lost on the 210 * mips, because CALL16 relocs must reference global symbols, and, if 211 * those symbols were being hidden, they were no longer global. 212 * 213 * The new renaming behaviour doesn't take global symbols out of the 214 * namespace. However, it's ... unlikely that there will ever be 215 * any collisions in practice because of the new method. 216 */ 217int 218ELFNAMEEND(hide)(int fd, const char *fn) 219{ 220 Elf_Ehdr ehdr; 221 struct shlayout *layoutp = NULL; 222 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr; 223 Elf_Shdr shdrshdr; 224 Elf_Sym *symtabp = NULL; 225 char *shstrtabp = NULL, *strtabp = NULL; 226 Elf_Size nsyms, ewi; 227 Elf_Off off; 228 ssize_t shdrsize; 229 int rv, i, weird, l, m, r, strtabidx; 230 size_t nstrtab_size, nstrtab_nextoff, fn_size, size; 231 char *nstrtabp = NULL; 232 unsigned char data; 233 const char *weirdreason = NULL; 234 void *buf; 235 Elf_Half shnum; 236 237 rv = 0; 238 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 239 goto bad; 240 241 data = ehdr.e_ident[EI_DATA]; 242 shnum = xe16toh(ehdr.e_shnum); 243 244 shdrsize = shnum * xe16toh(ehdr.e_shentsize); 245 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 246 goto bad; 247 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 248 shdrsize) 249 goto bad; 250 251 symtabshdr = strtabshdr = shstrtabshdr = NULL; 252 weird = 0; 253 for (i = 0; i < shnum; i++) { 254 switch (xe32toh(shdrp[i].sh_type)) { 255 case SHT_SYMTAB: 256 if (symtabshdr != NULL) { 257 weird = 1; 258 weirdreason = "multiple symbol tables"; 259 } 260 symtabshdr = &shdrp[i]; 261 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 262 break; 263 case SHT_STRTAB: 264 if (i == xe16toh(ehdr.e_shstrndx)) 265 shstrtabshdr = &shdrp[i]; 266 break; 267 } 268 } 269 if (symtabshdr == NULL) 270 goto out; 271 if (strtabshdr == NULL) { 272 weird = 1; 273 weirdreason = "string table does not exist"; 274 } 275 if (shstrtabshdr == NULL) { 276 weird = 1; 277 weirdreason = "section header string table does not exist"; 278 } 279 if (weirdreason == NULL) 280 weirdreason = "unsupported"; 281 if (weird) { 282 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 283 goto bad; 284 } 285 286 /* 287 * sort section layout table by offset 288 */ 289 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout), 290 fn, "layout table"); 291 if (layoutp == NULL) 292 goto bad; 293 294 /* add a pseudo entry to represent the section header table */ 295 shdrshdr.sh_offset = ehdr.e_shoff; 296 shdrshdr.sh_size = htoxew(shdrsize); 297 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8); 298 layoutp[shnum].shdr = &shdrshdr; 299 300 /* insert and sort normal section headers */ 301 for (i = shnum; i-- != 0;) { 302 l = i + 1; 303 r = shnum; 304 while (l <= r) { 305 m = ( l + r) / 2; 306 if (xewtoh(shdrp[i].sh_offset) > 307 xewtoh(layoutp[m].shdr->sh_offset)) 308 l = m + 1; 309 else 310 r = m - 1; 311 } 312 313 if (r != i) { 314 memmove(&layoutp[i], &layoutp[i + 1], 315 sizeof(struct shlayout) * (r - i)); 316 } 317 318 layoutp[r].shdr = &shdrp[i]; 319 layoutp[r].bufp = NULL; 320 } 321 ++shnum; 322 323 /* 324 * load up everything we need 325 */ 326 327 /* load section string table for debug use */ 328 if ((size = xewtoh(shstrtabshdr->sh_size)) == 0) 329 goto bad; 330 if ((shstrtabp = xmalloc(size, fn, "section string table")) == NULL) 331 goto bad; 332 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset), 333 size, fn) != size) 334 goto bad; 335 if (shstrtabp[size - 1] != '\0') 336 goto bad; 337 338 /* we need symtab, strtab, and everything behind strtab */ 339 strtabidx = INT_MAX; 340 for (i = 0; i < shnum; i++) { 341 if (layoutp[i].shdr == &shdrshdr) { 342 /* not load section header again */ 343 layoutp[i].bufp = shdrp; 344 continue; 345 } 346 if (layoutp[i].shdr == shstrtabshdr) { 347 /* not load section string table again */ 348 layoutp[i].bufp = shstrtabp; 349 continue; 350 } 351 352 if (layoutp[i].shdr == strtabshdr) 353 strtabidx = i; 354 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) { 355 off = xewtoh(layoutp[i].shdr->sh_offset); 356 if ((size = xewtoh(layoutp[i].shdr->sh_size)) == 0) 357 goto bad; 358 layoutp[i].bufp = xmalloc(size, fn, 359 shstrtabp + xewtoh(layoutp[i].shdr->sh_name)); 360 if (layoutp[i].bufp == NULL) 361 goto bad; 362 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) != 363 size) 364 goto bad; 365 366 /* set symbol table and string table */ 367 if (layoutp[i].shdr == symtabshdr) { 368 symtabp = layoutp[i].bufp; 369 } else if (layoutp[i].shdr == strtabshdr) { 370 strtabp = layoutp[i].bufp; 371 if (strtabp[size - 1] != '\0') 372 goto bad; 373 } 374 } 375 } 376 377 nstrtab_size = 256; 378 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 379 if (nstrtabp == NULL) 380 goto bad; 381 nstrtab_nextoff = 0; 382 383 fn_size = strlen(fn); 384 385 /* Prepare data structures for symbol movement. */ 386 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 387 388 /* move symbols, making them local */ 389 for (ewi = 0; ewi < nsyms; ewi++) { 390 Elf_Sym *sp = &symtabp[ewi]; 391 const char *symname = strtabp + xe32toh(sp->st_name); 392 size_t newent_len; 393 /* 394 * make sure there's size for the next entry, even if it's 395 * as large as it can be. 396 * 397 * "_$$hide$$ <filename> <symname><NUL>" -> 398 * 9 + 3 + sizes of fn and sym name 399 */ 400 while ((nstrtab_size - nstrtab_nextoff) < 401 strlen(symname) + fn_size + 12) { 402 nstrtab_size *= 2; 403 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 404 "new string table"); 405 if (nstrtabp == NULL) 406 goto bad; 407 } 408 409 sp->st_name = htowew(nstrtab_nextoff); 410 411 /* if it's a keeper or is undefined, don't rename it. */ 412 if (in_keep_list(symname) || 413 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 414 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 415 "%s", symname) + 1; 416 } else { 417 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 418 "_$$hide$$ %s %s", fn, symname) + 1; 419 } 420 nstrtab_nextoff += newent_len; 421 } 422 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 423 424 /* 425 * update section header table in ascending order of offset 426 */ 427 for (i = strtabidx + 1; i < shnum; i++) { 428 Elf_Off off, align; 429 off = xewtoh(layoutp[i - 1].shdr->sh_offset) + 430 xewtoh(layoutp[i - 1].shdr->sh_size); 431 align = xewtoh(layoutp[i].shdr->sh_addralign); 432 off = (off + (align - 1)) & ~(align - 1); 433 layoutp[i].shdr->sh_offset = htoxew(off); 434 } 435 436 /* 437 * write data to the file in descending order of offset 438 */ 439 for (i = shnum; i-- != 0;) { 440 if (layoutp[i].shdr == strtabshdr) { 441 /* new string table */ 442 buf = nstrtabp; 443 } else 444 buf = layoutp[i].bufp; 445 446 if (layoutp[i].shdr == &shdrshdr || 447 layoutp[i].shdr == symtabshdr || i >= strtabidx) { 448 if (buf == NULL) 449 goto bad; 450 451 /* 452 * update the offset of section header table in elf 453 * header if needed. 454 */ 455 if (layoutp[i].shdr == &shdrshdr && 456 ehdr.e_shoff != shdrshdr.sh_offset) { 457 ehdr.e_shoff = shdrshdr.sh_offset; 458 off = offsetof(Elf_Ehdr, e_shoff); 459 size = sizeof(Elf_Off); 460 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size, 461 fn) != size) 462 goto bad; 463 } 464 465 off = xewtoh(layoutp[i].shdr->sh_offset); 466 size = xewtoh(layoutp[i].shdr->sh_size); 467 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size) 468 goto bad; 469 } 470 } 471 472out: 473 if (layoutp != NULL) { 474 for (i = 0; i < shnum; i++) { 475 if (layoutp[i].bufp != NULL) 476 free(layoutp[i].bufp); 477 } 478 free(layoutp); 479 } 480 free(nstrtabp); 481 return (rv); 482 483bad: 484 rv = 1; 485 goto out; 486} 487 488#endif /* include this size of ELF */ 489