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 1.4 1997/08/12 06:07:24 mikel 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 <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <unistd.h> 52 53 #include "extern.h" 54 55 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 56 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 57 58 #define __ELF_WORD_SIZE ELFSIZE 59 #if (ELFSIZE == 32) 60 #include <sys/elf32.h> 61 #define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 62 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 63 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 64 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 65 #elif (ELFSIZE == 64) 66 #include <sys/elf64.h> 67 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 68 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 69 /* elf64 Elf64_Word are 32 bits */ 70 #define wewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 71 #define htowew(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 72 #endif 73 #include <sys/elf_generic.h> 74 75 #define CONCAT(x,y) __CONCAT(x,y) 76 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 77 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 78 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 79 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 80 81 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 82 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 83 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 84 85 struct listelem { 86 struct listelem *next; 87 void *mem; 88 off_t file; 89 size_t size; 90 }; 91 92 static ssize_t 93 xreadatoff(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 ((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 } 108 109 static ssize_t 110 xwriteatoff(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 ((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 } 125 126 static void * 127 xmalloc(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 } 137 138 static void * 139 xrealloc(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 } 151 152 int 153 ELFNAMEEND(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 < 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_ARM 179 #define EM_ARM 40 180 #endif 181 case EM_ARM: break; 182 #ifndef EM_MIPS 183 #define EM_MIPS 8 184 #endif 185 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */ 186 #define EM_MIPS_RS4_BE 10 187 #endif 188 case EM_MIPS: break; 189 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 190 #ifndef EM_IA_64 191 #define EM_IA_64 50 192 #endif 193 case EM_IA_64: break; 194 #ifndef EM_PPC 195 #define EM_PPC 20 196 #endif 197 case EM_PPC: break; 198 #ifndef EM_PPC64 199 #define EM_PPC64 21 200 #endif 201 case EM_PPC64: break; 202 #ifndef EM_SPARCV9 203 #define EM_SPARCV9 43 204 #endif 205 case EM_SPARCV9: break; 206 #ifndef EM_X86_64 207 #define EM_X86_64 62 208 #endif 209 case EM_X86_64: break; 210 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 211 212 default: 213 return 0; 214 } 215 216 return 1; 217 } 218 219 /* 220 * This function 'hides' (some of) ELF executable file's symbols. 221 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 222 * Symbols in the global keep list, or which are marked as being undefined, 223 * are left alone. 224 * 225 * An old version of this code shuffled various tables around, turning 226 * global symbols to be hidden into local symbols. That lost on the 227 * mips, because CALL16 relocs must reference global symbols, and, if 228 * those symbols were being hidden, they were no longer global. 229 * 230 * The new renaming behaviour doesn't take global symbols out of the 231 * namespace. However, it's ... unlikely that there will ever be 232 * any collisions in practice because of the new method. 233 */ 234 int 235 ELFNAMEEND(hide)(int fd, const char *fn) 236 { 237 Elf_Ehdr ehdr; 238 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr; 239 Elf_Sym *symtabp = NULL; 240 char *strtabp = NULL; 241 Elf_Size nsyms, nlocalsyms, ewi; 242 ssize_t shdrsize; 243 int rv, i, weird; 244 size_t nstrtab_size, nstrtab_nextoff, fn_size; 245 char *nstrtabp = NULL; 246 unsigned char data; 247 Elf_Off maxoff, stroff; 248 const char *weirdreason = NULL; 249 250 rv = 0; 251 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 252 goto bad; 253 254 data = ehdr.e_ident[EI_DATA]; 255 256 shdrsize = xe16toh(ehdr.e_shnum) * xe16toh(ehdr.e_shentsize); 257 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 258 goto bad; 259 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 260 shdrsize) 261 goto bad; 262 263 symtabshdr = strtabshdr = NULL; 264 weird = 0; 265 maxoff = stroff = 0; 266 for (i = 0; i < xe16toh(ehdr.e_shnum); i++) { 267 if (xewtoh(shdrp[i].sh_offset) > maxoff) 268 maxoff = xewtoh(shdrp[i].sh_offset); 269 switch (xe32toh(shdrp[i].sh_type)) { 270 case SHT_SYMTAB: 271 if (symtabshdr != NULL) 272 weird = 1; 273 symtabshdr = &shdrp[i]; 274 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 275 276 /* Check whether the string table is the last section */ 277 stroff = xewtoh(shdrp[xe32toh(shdrp[i].sh_link)].sh_offset); 278 if (!weird && xe32toh(shdrp[i].sh_link) != (xe16toh(ehdr.e_shnum) - 1)) { 279 weird = 1; 280 weirdreason = "string table not last section"; 281 } 282 break; 283 } 284 } 285 if (! weirdreason) 286 weirdreason = "unsupported"; 287 if (symtabshdr == NULL) 288 goto out; 289 if (strtabshdr == NULL) 290 weird = 1; 291 if (!weird && stroff != maxoff) { 292 weird = 1; 293 weirdreason = "string table section not last in file"; 294 } 295 if (weird) { 296 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 297 goto bad; 298 } 299 300 /* 301 * load up everything we need 302 */ 303 304 /* symbol table */ 305 if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table")) 306 == NULL) 307 goto bad; 308 if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 309 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 310 goto bad; 311 312 /* string table */ 313 if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table")) 314 == NULL) 315 goto bad; 316 if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset), 317 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 318 goto bad; 319 320 nstrtab_size = 256; 321 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 322 if (nstrtabp == NULL) 323 goto bad; 324 nstrtab_nextoff = 0; 325 326 fn_size = strlen(fn); 327 328 /* Prepare data structures for symbol movement. */ 329 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 330 nlocalsyms = xe32toh(symtabshdr->sh_info); 331 332 /* move symbols, making them local */ 333 for (ewi = 0; ewi < nsyms; ewi++) { 334 Elf_Sym *sp = &symtabp[ewi]; 335 const char *symname = strtabp + xe32toh(sp->st_name); 336 size_t newent_len; 337 /* 338 * make sure there's size for the next entry, even if it's 339 * as large as it can be. 340 * 341 * "_$$hide$$ <filename> <symname><NUL>" -> 342 * 9 + 3 + sizes of fn and sym name 343 */ 344 while ((nstrtab_size - nstrtab_nextoff) < 345 strlen(symname) + fn_size + 12) { 346 nstrtab_size *= 2; 347 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 348 "new string table"); 349 if (nstrtabp == NULL) 350 goto bad; 351 } 352 353 sp->st_name = htowew(nstrtab_nextoff); 354 355 /* if it's a keeper or is undefined, don't rename it. */ 356 if (in_keep_list(symname) || 357 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 358 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 359 "%s", symname) + 1; 360 } else { 361 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 362 "_$$hide$$ %s %s", fn, symname) + 1; 363 } 364 nstrtab_nextoff += newent_len; 365 } 366 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 367 368 /* 369 * write new tables to the file 370 */ 371 if (xwriteatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 372 shdrsize) 373 goto bad; 374 if (xwriteatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 375 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 376 goto bad; 377 /* write new symbol table strings */ 378 if ((size_t)xwriteatoff(fd, nstrtabp, xewtoh(strtabshdr->sh_offset), 379 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 380 goto bad; 381 382 out: 383 if (shdrp != NULL) 384 free(shdrp); 385 if (symtabp != NULL) 386 free(symtabp); 387 if (strtabp != NULL) 388 free(strtabp); 389 return (rv); 390 391 bad: 392 rv = 1; 393 goto out; 394 } 395 396 #endif /* include this size of ELF */ 397