1 /*- 2 * SPDX-License-Identifier: BSD-4-Clause 3 * 4 * Copyright (c) 1997 Christopher G. Demetriou. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Christopher G. Demetriou 17 * for the NetBSD Project. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <sys/cdefs.h> 34 #ifndef lint 35 #if 0 36 __RCSID("$NetBSD: exec_elf32.c,v 1.6 1999/09/20 04:12:16 christos Exp $"); 37 #endif 38 #endif 39 __FBSDID("$FreeBSD$"); 40 41 #ifndef ELFSIZE 42 #define ELFSIZE 32 43 #endif 44 45 #include <sys/types.h> 46 #include <sys/endian.h> 47 #include <sys/stat.h> 48 49 #include <errno.h> 50 #include <limits.h> 51 #include <stddef.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <unistd.h> 56 57 #include "extern.h" 58 59 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 60 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 61 62 #define __ELF_WORD_SIZE ELFSIZE 63 #if (ELFSIZE == 32) 64 #include <sys/elf32.h> 65 #define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 66 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 67 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 68 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 69 #elif (ELFSIZE == 64) 70 #include <sys/elf64.h> 71 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 72 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 73 /* elf64 Elf64_Word are 32 bits */ 74 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 75 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 76 #endif 77 #include <sys/elf_generic.h> 78 79 #define CONCAT(x,y) __CONCAT(x,y) 80 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 81 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 82 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 83 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 84 #ifndef ELFCLASS 85 #define ELFCLASS CONCAT(ELFCLASS,ELFSIZE) 86 #endif 87 88 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 89 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 90 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 91 92 struct shlayout { 93 Elf_Shdr *shdr; 94 void *bufp; 95 }; 96 97 static ssize_t 98 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 99 { 100 ssize_t rv; 101 102 if (lseek(fd, off, SEEK_SET) != off) { 103 perror(fn); 104 return -1; 105 } 106 if ((size_t)(rv = read(fd, buf, size)) != size) { 107 fprintf(stderr, "%s: read error: %s\n", fn, 108 rv == -1 ? strerror(errno) : "short read"); 109 return -1; 110 } 111 return size; 112 } 113 114 static ssize_t 115 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 116 { 117 ssize_t rv; 118 119 if (lseek(fd, off, SEEK_SET) != off) { 120 perror(fn); 121 return -1; 122 } 123 if ((size_t)(rv = write(fd, buf, size)) != size) { 124 fprintf(stderr, "%s: write error: %s\n", fn, 125 rv == -1 ? strerror(errno) : "short write"); 126 return -1; 127 } 128 return size; 129 } 130 131 static void * 132 xmalloc(size_t size, const char *fn, const char *use) 133 { 134 void *rv; 135 136 rv = malloc(size); 137 if (rv == NULL) 138 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 139 fn, use); 140 return (rv); 141 } 142 143 static void * 144 xrealloc(void *ptr, size_t size, const char *fn, const char *use) 145 { 146 void *rv; 147 148 rv = realloc(ptr, size); 149 if (rv == NULL) { 150 free(ptr); 151 fprintf(stderr, "%s: out of memory (reallocating for %s)\n", 152 fn, use); 153 } 154 return (rv); 155 } 156 157 int 158 ELFNAMEEND(check)(int fd, const char *fn) 159 { 160 Elf_Ehdr eh; 161 struct stat sb; 162 unsigned char data; 163 164 /* 165 * Check the header to maek sure it's an ELF file (of the 166 * appropriate size). 167 */ 168 if (fstat(fd, &sb) == -1) 169 return 0; 170 if (sb.st_size < (off_t)(sizeof eh)) 171 return 0; 172 if (read(fd, &eh, sizeof eh) != sizeof eh) 173 return 0; 174 175 if (IS_ELF(eh) == 0 || eh.e_ident[EI_CLASS] != ELFCLASS) 176 return 0; 177 178 data = eh.e_ident[EI_DATA]; 179 180 switch (xe16toh(eh.e_machine)) { 181 case EM_386: break; 182 case EM_ALPHA: break; 183 #ifndef EM_AARCH64 184 #define EM_AARCH64 183 185 #endif 186 case EM_AARCH64: break; 187 case EM_ARM: break; 188 case EM_MIPS: break; 189 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 190 case EM_PPC: break; 191 case EM_PPC64: break; 192 #ifndef EM_RISCV 193 #define EM_RISCV 243 194 #endif 195 case EM_RISCV: break; 196 case EM_S390: break; 197 case EM_SPARCV9: break; 198 case EM_X86_64: break; 199 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 200 201 default: 202 return 0; 203 } 204 205 return 1; 206 } 207 208 /* 209 * This function 'hides' (some of) ELF executable file's symbols. 210 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 211 * Symbols in the global keep list, or which are marked as being undefined, 212 * are left alone. 213 * 214 * An old version of this code shuffled various tables around, turning 215 * global symbols to be hidden into local symbols. That lost on the 216 * mips, because CALL16 relocs must reference global symbols, and, if 217 * those symbols were being hidden, they were no longer global. 218 * 219 * The new renaming behaviour doesn't take global symbols out of the 220 * namespace. However, it's ... unlikely that there will ever be 221 * any collisions in practice because of the new method. 222 */ 223 int 224 ELFNAMEEND(hide)(int fd, const char *fn) 225 { 226 Elf_Ehdr ehdr; 227 struct shlayout *layoutp = NULL; 228 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr, *shstrtabshdr; 229 Elf_Shdr shdrshdr; 230 Elf_Sym *symtabp = NULL; 231 char *shstrtabp = NULL, *strtabp = NULL; 232 Elf_Size nsyms, ewi; 233 Elf_Off off; 234 ssize_t shdrsize; 235 int rv, i, weird, l, m, r, strtabidx; 236 size_t nstrtab_size, nstrtab_nextoff, fn_size, size; 237 char *nstrtabp = NULL; 238 unsigned char data; 239 const char *weirdreason = NULL; 240 void *buf; 241 Elf_Half shnum; 242 243 rv = 0; 244 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 245 goto bad; 246 247 data = ehdr.e_ident[EI_DATA]; 248 shnum = xe16toh(ehdr.e_shnum); 249 250 shdrsize = shnum * xe16toh(ehdr.e_shentsize); 251 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 252 goto bad; 253 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 254 shdrsize) 255 goto bad; 256 257 symtabshdr = strtabshdr = shstrtabshdr = NULL; 258 weird = 0; 259 for (i = 0; i < shnum; i++) { 260 switch (xe32toh(shdrp[i].sh_type)) { 261 case SHT_SYMTAB: 262 if (symtabshdr != NULL) { 263 weird = 1; 264 weirdreason = "multiple symbol tables"; 265 } 266 symtabshdr = &shdrp[i]; 267 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 268 break; 269 case SHT_STRTAB: 270 if (i == xe16toh(ehdr.e_shstrndx)) 271 shstrtabshdr = &shdrp[i]; 272 break; 273 } 274 } 275 if (symtabshdr == NULL) 276 goto out; 277 if (strtabshdr == NULL) { 278 weird = 1; 279 weirdreason = "string table does not exist"; 280 } 281 if (shstrtabshdr == NULL) { 282 weird = 1; 283 weirdreason = "section header string table does not exist"; 284 } 285 if (strtabshdr == shstrtabshdr) { 286 weird = 1; 287 weirdreason = "combined strtab and shstrtab not supported"; 288 } 289 if (weirdreason == NULL) 290 weirdreason = "unsupported"; 291 if (weird) { 292 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 293 goto bad; 294 } 295 296 /* 297 * sort section layout table by offset 298 */ 299 layoutp = xmalloc((shnum + 1) * sizeof(struct shlayout), 300 fn, "layout table"); 301 if (layoutp == NULL) 302 goto bad; 303 304 /* add a pseudo entry to represent the section header table */ 305 shdrshdr.sh_offset = ehdr.e_shoff; 306 shdrshdr.sh_size = htoxew(shdrsize); 307 shdrshdr.sh_addralign = htoxew(ELFSIZE / 8); 308 layoutp[shnum].shdr = &shdrshdr; 309 310 /* insert and sort normal section headers */ 311 for (i = shnum; i-- != 0;) { 312 l = i + 1; 313 r = shnum; 314 while (l <= r) { 315 m = ( l + r) / 2; 316 if (xewtoh(shdrp[i].sh_offset) > 317 xewtoh(layoutp[m].shdr->sh_offset)) 318 l = m + 1; 319 else 320 r = m - 1; 321 } 322 323 if (r != i) { 324 memmove(&layoutp[i], &layoutp[i + 1], 325 sizeof(struct shlayout) * (r - i)); 326 } 327 328 layoutp[r].shdr = &shdrp[i]; 329 layoutp[r].bufp = NULL; 330 } 331 ++shnum; 332 333 /* 334 * load up everything we need 335 */ 336 337 /* load section string table for debug use */ 338 if ((size = xewtoh(shstrtabshdr->sh_size)) == 0) 339 goto bad; 340 if ((shstrtabp = xmalloc(size, fn, "section string table")) == NULL) 341 goto bad; 342 if ((size_t)xreadatoff(fd, shstrtabp, xewtoh(shstrtabshdr->sh_offset), 343 size, fn) != size) 344 goto bad; 345 if (shstrtabp[size - 1] != '\0') 346 goto bad; 347 348 /* we need symtab, strtab, and everything behind strtab */ 349 strtabidx = INT_MAX; 350 for (i = 0; i < shnum; i++) { 351 if (layoutp[i].shdr == &shdrshdr) { 352 /* not load section header again */ 353 layoutp[i].bufp = shdrp; 354 continue; 355 } 356 if (layoutp[i].shdr == shstrtabshdr) { 357 /* not load section string table again */ 358 layoutp[i].bufp = shstrtabp; 359 continue; 360 } 361 362 if (layoutp[i].shdr == strtabshdr) 363 strtabidx = i; 364 if (layoutp[i].shdr == symtabshdr || i >= strtabidx) { 365 off = xewtoh(layoutp[i].shdr->sh_offset); 366 if ((size = xewtoh(layoutp[i].shdr->sh_size)) == 0) 367 goto bad; 368 layoutp[i].bufp = xmalloc(size, fn, 369 shstrtabp + xewtoh(layoutp[i].shdr->sh_name)); 370 if (layoutp[i].bufp == NULL) 371 goto bad; 372 if ((size_t)xreadatoff(fd, layoutp[i].bufp, off, size, fn) != 373 size) 374 goto bad; 375 376 /* set symbol table and string table */ 377 if (layoutp[i].shdr == symtabshdr) { 378 symtabp = layoutp[i].bufp; 379 } else if (layoutp[i].shdr == strtabshdr) { 380 strtabp = layoutp[i].bufp; 381 if (strtabp[size - 1] != '\0') 382 goto bad; 383 } 384 } 385 } 386 387 nstrtab_size = 256; 388 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 389 if (nstrtabp == NULL) 390 goto bad; 391 nstrtab_nextoff = 0; 392 393 fn_size = strlen(fn); 394 395 /* Prepare data structures for symbol movement. */ 396 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 397 398 /* move symbols, making them local */ 399 for (ewi = 0; ewi < nsyms; ewi++) { 400 Elf_Sym *sp = &symtabp[ewi]; 401 const char *symname = strtabp + xe32toh(sp->st_name); 402 size_t newent_len; 403 /* 404 * make sure there's size for the next entry, even if it's 405 * as large as it can be. 406 * 407 * "_$$hide$$ <filename> <symname><NUL>" -> 408 * 9 + 3 + sizes of fn and sym name 409 */ 410 while ((nstrtab_size - nstrtab_nextoff) < 411 strlen(symname) + fn_size + 12) { 412 nstrtab_size *= 2; 413 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 414 "new string table"); 415 if (nstrtabp == NULL) 416 goto bad; 417 } 418 419 sp->st_name = htowew(nstrtab_nextoff); 420 421 /* if it's a keeper or is undefined, don't rename it. */ 422 if (in_keep_list(symname) || 423 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 424 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 425 "%s", symname) + 1; 426 } else { 427 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 428 "_$$hide$$ %s %s", fn, symname) + 1; 429 } 430 nstrtab_nextoff += newent_len; 431 } 432 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 433 434 /* 435 * update section header table in ascending order of offset 436 */ 437 for (i = strtabidx + 1; i < shnum; i++) { 438 Elf_Off off, align; 439 off = xewtoh(layoutp[i - 1].shdr->sh_offset) + 440 xewtoh(layoutp[i - 1].shdr->sh_size); 441 align = xewtoh(layoutp[i].shdr->sh_addralign); 442 off = (off + (align - 1)) & ~(align - 1); 443 layoutp[i].shdr->sh_offset = htoxew(off); 444 } 445 446 /* 447 * write data to the file in descending order of offset 448 */ 449 for (i = shnum; i-- != 0;) { 450 if (layoutp[i].shdr == strtabshdr) { 451 /* new string table */ 452 buf = nstrtabp; 453 } else 454 buf = layoutp[i].bufp; 455 456 if (layoutp[i].shdr == &shdrshdr || 457 layoutp[i].shdr == symtabshdr || i >= strtabidx) { 458 if (buf == NULL) 459 goto bad; 460 461 /* 462 * update the offset of section header table in elf 463 * header if needed. 464 */ 465 if (layoutp[i].shdr == &shdrshdr && 466 ehdr.e_shoff != shdrshdr.sh_offset) { 467 ehdr.e_shoff = shdrshdr.sh_offset; 468 off = offsetof(Elf_Ehdr, e_shoff); 469 size = sizeof(Elf_Off); 470 if ((size_t)xwriteatoff(fd, &ehdr.e_shoff, off, size, 471 fn) != size) 472 goto bad; 473 } 474 475 off = xewtoh(layoutp[i].shdr->sh_offset); 476 size = xewtoh(layoutp[i].shdr->sh_size); 477 if ((size_t)xwriteatoff(fd, buf, off, size, fn) != size) 478 goto bad; 479 } 480 } 481 482 out: 483 if (layoutp != NULL) { 484 for (i = 0; i < shnum; i++) { 485 if (layoutp[i].bufp != NULL) 486 free(layoutp[i].bufp); 487 } 488 free(layoutp); 489 } 490 free(nstrtabp); 491 return (rv); 492 493 bad: 494 rv = 1; 495 goto out; 496 } 497 498 #endif /* include this size of ELF */ 499