exec_elf32.c revision 112767
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: head/usr.sbin/crunch/crunchide/exec_elf32.c 112767 2003-03-29 03:03:42Z obrien $"); 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 80struct listelem { 81 struct listelem *next; 82 void *mem; 83 off_t file; 84 size_t size; 85}; 86 87static ssize_t 88xreadatoff(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 104static ssize_t 105xwriteatoff(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 121static void * 122xmalloc(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 133int 134ELFNAMEEND(check)(int fd, const char *fn) 135{ 136 Elf_Ehdr eh; 137 struct stat sb; 138 unsigned char data; 139 140 /* 141 * Check the header to maek sure it's an ELF file (of the 142 * appropriate size). 143 */ 144 if (fstat(fd, &sb) == -1) 145 return 0; 146 if (sb.st_size < sizeof eh) 147 return 0; 148 if (read(fd, &eh, sizeof eh) != sizeof eh) 149 return 0; 150 151 if (IS_ELF(eh) == 0) 152 return 0; 153 154 data = eh.e_ident[EI_DATA]; 155 156 switch (xe16toh(eh.e_machine)) { 157 case EM_386: break; 158 case EM_ALPHA: break; 159#ifndef EM_IA_64 160#define EM_IA_64 50 161#endif 162 case EM_IA_64: break; 163#ifndef EM_SPARCV9 164#define EM_SPARCV9 43 165#endif 166 case EM_SPARCV9: break; 167/* ELFDEFNNAME(MACHDEP_ID_CASES) */ 168 169 default: 170 return 0; 171 } 172 173 return 1; 174} 175 176int 177ELFNAMEEND(hide)(int fd, const char *fn) 178{ 179 Elf_Ehdr ehdr; 180 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr; 181 Elf_Sym *symtabp = NULL; 182 char *strtabp = NULL; 183 Elf_Word *symfwmap = NULL, *symrvmap = NULL, nsyms, nlocalsyms, ewi; 184 struct listelem *relalist = NULL, *rellist = NULL, *tmpl; 185 ssize_t shdrsize; 186 int rv, i, weird; 187 unsigned char data; 188 189 rv = 0; 190 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 191 goto bad; 192 193 data = ehdr.e_ident[EI_DATA]; 194 195 shdrsize = xe16toh(ehdr.e_shnum) * xe16toh(ehdr.e_shentsize); 196 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 197 goto bad; 198 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 199 shdrsize) 200 goto bad; 201 202 symtabshdr = strtabshdr = NULL; 203 weird = 0; 204 for (i = 0; i < xe16toh(ehdr.e_shnum); i++) { 205 switch (xe32toh(shdrp[i].sh_type)) { 206 case SHT_SYMTAB: 207 if (symtabshdr != NULL) 208 weird = 1; 209 symtabshdr = &shdrp[i]; 210 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 211 break; 212 case SHT_RELA: 213 tmpl = xmalloc(sizeof *tmpl, fn, "rela list element"); 214 if (tmpl == NULL) 215 goto bad; 216 tmpl->mem = NULL; 217 tmpl->file = shdrp[i].sh_offset; 218 tmpl->size = shdrp[i].sh_size; 219 tmpl->next = relalist; 220 relalist = tmpl; 221 break; 222 case SHT_REL: 223 tmpl = xmalloc(sizeof *tmpl, fn, "rel list element"); 224 if (tmpl == NULL) 225 goto bad; 226 tmpl->mem = NULL; 227 tmpl->file = shdrp[i].sh_offset; 228 tmpl->size = shdrp[i].sh_size; 229 tmpl->next = rellist; 230 rellist = tmpl; 231 break; 232 } 233 } 234 if (symtabshdr == NULL) 235 goto out; 236 if (strtabshdr == NULL) 237 weird = 1; 238 if (weird) { 239 fprintf(stderr, "%s: weird executable (unsupported)\n", fn); 240 goto bad; 241 } 242 243 /* 244 * load up everything we need 245 */ 246 247 /* symbol table */ 248 if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table")) 249 == NULL) 250 goto bad; 251 if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 252 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 253 goto bad; 254 255 /* string table */ 256 if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table")) 257 == NULL) 258 goto bad; 259 if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset), 260 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 261 goto bad; 262 263 /* any rela tables */ 264 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 265 if ((tmpl->mem = xmalloc(xewtoh(tmpl->size), fn, "rela table")) 266 == NULL) 267 goto bad; 268 if (xreadatoff(fd, tmpl->mem, xewtoh(tmpl->file), 269 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 270 goto bad; 271 } 272 273 /* any rel tables */ 274 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 275 if ((tmpl->mem = xmalloc(xewtoh(tmpl->size), fn, "rel table")) 276 == NULL) 277 goto bad; 278 if (xreadatoff(fd, tmpl->mem, xewtoh(tmpl->file), 279 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 280 goto bad; 281 } 282 283 /* Prepare data structures for symbol movement. */ 284 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 285 nlocalsyms = xe32toh(symtabshdr->sh_info); 286 if ((symfwmap = xmalloc(nsyms * sizeof (Elf_Word), fn, 287 "symbol forward mapping table")) == NULL) 288 goto bad; 289 if ((symrvmap = xmalloc(nsyms * sizeof (Elf_Word), fn, 290 "symbol reverse mapping table")) == NULL) 291 goto bad; 292 293 /* init location -> symbol # table */ 294 for (ewi = 0; ewi < nsyms; ewi++) 295 symrvmap[ewi] = ewi; 296 297 /* move symbols, making them local */ 298 for (ewi = nlocalsyms; ewi < nsyms; ewi++) { 299 Elf_Sym *sp, symswap; 300 Elf_Word mapswap; 301 302 sp = &symtabp[ewi]; 303 304 /* if it's on our keep list, don't move it */ 305 if (in_keep_list(strtabp + xe32toh(sp->st_name))) 306 continue; 307 308 /* if it's an undefined symbol, keep it */ 309 if (xe16toh(sp->st_shndx) == SHN_UNDEF) 310 continue; 311 312 /* adjust the symbol so that it's local */ 313 sp->st_info = 314 ELF_ST_INFO(STB_LOCAL, sp->st_info); 315/* (STB_LOCAL << 4) | ELF_SYM_TYPE(sp->st_info); *//* XXX */ 316 317 /* 318 * move the symbol to its new location 319 */ 320 321 /* note that symbols in those locations have been swapped */ 322 mapswap = symrvmap[ewi]; 323 symrvmap[ewi] = symrvmap[nlocalsyms]; 324 symrvmap[nlocalsyms] = mapswap; 325 326 /* and swap the symbols */ 327 symswap = *sp; 328 *sp = symtabp[nlocalsyms]; 329 symtabp[nlocalsyms] = symswap; 330 331 nlocalsyms++; /* note new local sym */ 332 } 333 symtabshdr->sh_info = htoxe32(nlocalsyms); 334 335 /* set up symbol # -> location mapping table */ 336 for (ewi = 0; ewi < nsyms; ewi++) 337 symfwmap[symrvmap[ewi]] = ewi; 338 339 /* any rela tables */ 340 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 341 Elf_Rela *relap = tmpl->mem; 342 343 for (ewi = 0; ewi < xewtoh(tmpl->size) / sizeof(*relap); ewi++) { 344 relap[ewi].r_info = htoxew(ELF_R_INFO( 345 symfwmap[ELF_R_SYM(xewtoh(relap[ewi].r_info))], 346 ELF_R_TYPE(xewtoh(relap[ewi].r_info)) 347 )); 348 } 349 } 350 351 /* any rel tables */ 352 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 353 Elf_Rel *relp = tmpl->mem; 354 355 for (ewi = 0; ewi < xewtoh(tmpl->size) / sizeof *relp; ewi++) { 356 relp[ewi].r_info = htoxew(ELF_R_INFO( 357 symfwmap[ELF_R_SYM(xewtoh(relp[ewi].r_info))], 358 ELF_R_TYPE(xewtoh(relp[ewi].r_info)) 359 )); 360 } 361 } 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 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 373 if (xwriteatoff(fd, tmpl->mem, xewtoh(tmpl->file), 374 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 375 goto bad; 376 } 377 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 378 if (xwriteatoff(fd, tmpl->mem, xewtoh(tmpl->file), 379 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 380 goto bad; 381 } 382 383out: 384 if (shdrp != NULL) 385 free(shdrp); 386 if (symtabp != NULL) 387 free(symtabp); 388 if (strtabp != NULL) 389 free(strtabp); 390 if (symfwmap != NULL) 391 free(symfwmap); 392 if (symrvmap != NULL) 393 free(symrvmap); 394 while ((tmpl = relalist) != NULL) { 395 relalist = tmpl->next; 396 if (tmpl->mem != NULL) 397 free(tmpl->mem); 398 free(tmpl); 399 } 400 while ((tmpl = rellist) != NULL) { 401 rellist = tmpl->next; 402 if (tmpl->mem != NULL) 403 free(tmpl->mem); 404 free(tmpl); 405 } 406 return (rv); 407 408bad: 409 rv = 1; 410 goto out; 411} 412 413#endif /* include this size of ELF */ 414