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 #elif (ELFSIZE == 64) 64 #include <sys/elf64.h> 65 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 66 #define htoxew(x) ((data == ELFDATA2MSB) ? htobe64(x) : htole64(x)) 67 #endif 68 #include <sys/elf_generic.h> 69 70 #define CONCAT(x,y) __CONCAT(x,y) 71 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 72 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 73 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 74 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 75 76 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 77 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 78 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 79 80 struct listelem { 81 struct listelem *next; 82 void *mem; 83 off_t file; 84 size_t size; 85 }; 86 87 static ssize_t 88 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 89 { 90 ssize_t rv; 91 92 if (lseek(fd, off, SEEK_SET) != off) { 93 perror(fn); 94 return -1; 95 } 96 if ((rv = read(fd, buf, size)) != size) { 97 fprintf(stderr, "%s: read error: %s\n", fn, 98 rv == -1 ? strerror(errno) : "short read"); 99 return -1; 100 } 101 return size; 102 } 103 104 static ssize_t 105 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 106 { 107 ssize_t rv; 108 109 if (lseek(fd, off, SEEK_SET) != off) { 110 perror(fn); 111 return -1; 112 } 113 if ((rv = write(fd, buf, size)) != size) { 114 fprintf(stderr, "%s: write error: %s\n", fn, 115 rv == -1 ? strerror(errno) : "short write"); 116 return -1; 117 } 118 return size; 119 } 120 121 static void * 122 xmalloc(size_t size, const char *fn, const char *use) 123 { 124 void *rv; 125 126 rv = malloc(size); 127 if (rv == NULL) 128 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 129 fn, use); 130 return (rv); 131 } 132 133 static void * 134 xrealloc(void *ptr, size_t size, const char *fn, const char *use) 135 { 136 void *rv; 137 138 rv = realloc(ptr, size); 139 if (rv == NULL) { 140 free(ptr); 141 fprintf(stderr, "%s: out of memory (reallocating for %s)\n", 142 fn, use); 143 } 144 return (rv); 145 } 146 147 int 148 ELFNAMEEND(check)(int fd, const char *fn) 149 { 150 Elf_Ehdr eh; 151 struct stat sb; 152 unsigned char data; 153 154 /* 155 * Check the header to maek sure it's an ELF file (of the 156 * appropriate size). 157 */ 158 if (fstat(fd, &sb) == -1) 159 return 0; 160 if (sb.st_size < sizeof eh) 161 return 0; 162 if (read(fd, &eh, sizeof eh) != sizeof eh) 163 return 0; 164 165 if (IS_ELF(eh) == 0) 166 return 0; 167 168 data = eh.e_ident[EI_DATA]; 169 170 switch (xe16toh(eh.e_machine)) { 171 case EM_386: break; 172 case EM_ALPHA: break; 173 #ifndef EM_ARM 174 #define EM_ARM 40 175 #endif 176 case EM_ARM: break; 177 #ifndef EM_MIPS 178 #define EM_MIPS 8 179 #endif 180 #ifndef EM_MIPS_RS4_BE /* same as EM_MIPS_RS3_LE */ 181 #define EM_MIPS_RS4_BE 10 182 #endif 183 case EM_MIPS: break; 184 case /* EM_MIPS_RS3_LE */ EM_MIPS_RS4_BE: break; 185 #ifndef EM_IA_64 186 #define EM_IA_64 50 187 #endif 188 case EM_IA_64: break; 189 #ifndef EM_PPC 190 #define EM_PPC 20 191 #endif 192 case EM_PPC: break; 193 #ifndef EM_PPC64 194 #define EM_PPC64 21 195 #endif 196 case EM_PPC64: break; 197 #ifndef EM_SPARCV9 198 #define EM_SPARCV9 43 199 #endif 200 case EM_SPARCV9: break; 201 #ifndef EM_X86_64 202 #define EM_X86_64 62 203 #endif 204 case EM_X86_64: break; 205 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 206 207 default: 208 return 0; 209 } 210 211 return 1; 212 } 213 214 /* 215 * This function 'hides' (some of) ELF executable file's symbols. 216 * It hides them by renaming them to "_$$hide$$ <filename> <symbolname>". 217 * Symbols in the global keep list, or which are marked as being undefined, 218 * are left alone. 219 * 220 * An old version of this code shuffled various tables around, turning 221 * global symbols to be hidden into local symbols. That lost on the 222 * mips, because CALL16 relocs must reference global symbols, and, if 223 * those symbols were being hidden, they were no longer global. 224 * 225 * The new renaming behaviour doesn't take global symbols out of the 226 * namespace. However, it's ... unlikely that there will ever be 227 * any collisions in practice because of the new method. 228 */ 229 int 230 ELFNAMEEND(hide)(int fd, const char *fn) 231 { 232 Elf_Ehdr ehdr; 233 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr; 234 Elf_Sym *symtabp = NULL; 235 char *strtabp = NULL; 236 Elf_Size nsyms, nlocalsyms, ewi; 237 ssize_t shdrsize; 238 int rv, i, weird; 239 size_t nstrtab_size, nstrtab_nextoff, fn_size; 240 char *nstrtabp = NULL; 241 unsigned char data; 242 Elf_Off maxoff, stroff; 243 const char *weirdreason = NULL; 244 245 rv = 0; 246 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 247 goto bad; 248 249 data = ehdr.e_ident[EI_DATA]; 250 251 shdrsize = xe16toh(ehdr.e_shnum) * xe16toh(ehdr.e_shentsize); 252 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 253 goto bad; 254 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 255 shdrsize) 256 goto bad; 257 258 symtabshdr = strtabshdr = NULL; 259 weird = 0; 260 maxoff = stroff = 0; 261 for (i = 0; i < xe16toh(ehdr.e_shnum); i++) { 262 if (xewtoh(shdrp[i].sh_offset) > maxoff) 263 maxoff = xewtoh(shdrp[i].sh_offset); 264 switch (xe32toh(shdrp[i].sh_type)) { 265 case SHT_SYMTAB: 266 if (symtabshdr != NULL) 267 weird = 1; 268 symtabshdr = &shdrp[i]; 269 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 270 271 /* Check whether the string table is the last section */ 272 stroff = xewtoh(shdrp[xe32toh(shdrp[i].sh_link)].sh_offset); 273 if (!weird && xe32toh(shdrp[i].sh_link) != (xe16toh(ehdr.e_shnum) - 1)) { 274 weird = 1; 275 weirdreason = "string table not last section"; 276 } 277 break; 278 } 279 } 280 if (! weirdreason) 281 weirdreason = "unsupported"; 282 if (symtabshdr == NULL) 283 goto out; 284 if (strtabshdr == NULL) 285 weird = 1; 286 if (!weird && stroff != maxoff) { 287 weird = 1; 288 weirdreason = "string table section not last in file"; 289 } 290 if (weird) { 291 fprintf(stderr, "%s: weird executable (%s)\n", fn, weirdreason); 292 goto bad; 293 } 294 295 /* 296 * load up everything we need 297 */ 298 299 /* symbol table */ 300 if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table")) 301 == NULL) 302 goto bad; 303 if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 304 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 305 goto bad; 306 307 /* string table */ 308 if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table")) 309 == NULL) 310 goto bad; 311 if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset), 312 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 313 goto bad; 314 315 nstrtab_size = 256; 316 nstrtabp = xmalloc(nstrtab_size, fn, "new string table"); 317 if (nstrtabp == NULL) 318 goto bad; 319 nstrtab_nextoff = 0; 320 321 fn_size = strlen(fn); 322 323 /* Prepare data structures for symbol movement. */ 324 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 325 nlocalsyms = xe32toh(symtabshdr->sh_info); 326 327 /* move symbols, making them local */ 328 for (ewi = 0; ewi < nsyms; ewi++) { 329 Elf_Sym *sp = &symtabp[ewi]; 330 const char *symname = strtabp + xe32toh(sp->st_name); 331 size_t newent_len; 332 /* 333 * make sure there's size for the next entry, even if it's 334 * as large as it can be. 335 * 336 * "_$$hide$$ <filename> <symname><NUL>" -> 337 * 9 + 3 + sizes of fn and sym name 338 */ 339 while ((nstrtab_size - nstrtab_nextoff) < 340 strlen(symname) + fn_size + 12) { 341 nstrtab_size *= 2; 342 nstrtabp = xrealloc(nstrtabp, nstrtab_size, fn, 343 "new string table"); 344 if (nstrtabp == NULL) 345 goto bad; 346 } 347 348 sp->st_name = htoxew(nstrtab_nextoff); 349 350 /* if it's a keeper or is undefined, don't rename it. */ 351 if (in_keep_list(symname) || 352 (xe16toh(sp->st_shndx) == SHN_UNDEF)) { 353 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 354 "%s", symname) + 1; 355 } else { 356 newent_len = sprintf(nstrtabp + nstrtab_nextoff, 357 "_$$hide$$ %s %s", fn, symname) + 1; 358 } 359 nstrtab_nextoff += newent_len; 360 } 361 strtabshdr->sh_size = htoxew(nstrtab_nextoff); 362 363 /* 364 * write new tables to the file 365 */ 366 if (xwriteatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 367 shdrsize) 368 goto bad; 369 if (xwriteatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 370 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 371 goto bad; 372 /* write new symbol table strings */ 373 if ((size_t)xwriteatoff(fd, nstrtabp, xewtoh(strtabshdr->sh_offset), 374 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 375 goto bad; 376 377 out: 378 if (shdrp != NULL) 379 free(shdrp); 380 if (symtabp != NULL) 381 free(symtabp); 382 if (strtabp != NULL) 383 free(strtabp); 384 return (rv); 385 386 bad: 387 rv = 1; 388 goto out; 389 } 390 391 #endif /* include this size of ELF */ 392