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 int 134 ELFNAMEEND(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_ARM 160 #define EM_ARM 40 161 #endif 162 case EM_ARM: break; 163 #ifndef EM_IA_64 164 #define EM_IA_64 50 165 #endif 166 case EM_IA_64: break; 167 #ifndef EM_PPC 168 #define EM_PPC 20 169 #endif 170 case EM_PPC: break; 171 #ifndef EM_SPARCV9 172 #define EM_SPARCV9 43 173 #endif 174 case EM_SPARCV9: break; 175 #ifndef EM_X86_64 176 #define EM_X86_64 62 177 #endif 178 case EM_X86_64: break; 179 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 180 181 default: 182 return 0; 183 } 184 185 return 1; 186 } 187 188 int 189 ELFNAMEEND(hide)(int fd, const char *fn) 190 { 191 Elf_Ehdr ehdr; 192 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr; 193 Elf_Sym *symtabp = NULL; 194 char *strtabp = NULL; 195 Elf_Size *symfwmap = NULL, *symrvmap = NULL, nsyms, nlocalsyms, ewi; 196 struct listelem *relalist = NULL, *rellist = NULL, *tmpl; 197 ssize_t shdrsize; 198 int rv, i, weird; 199 unsigned char data; 200 201 rv = 0; 202 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 203 goto bad; 204 205 data = ehdr.e_ident[EI_DATA]; 206 207 shdrsize = xe16toh(ehdr.e_shnum) * xe16toh(ehdr.e_shentsize); 208 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 209 goto bad; 210 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 211 shdrsize) 212 goto bad; 213 214 symtabshdr = strtabshdr = NULL; 215 weird = 0; 216 for (i = 0; i < xe16toh(ehdr.e_shnum); i++) { 217 switch (xe32toh(shdrp[i].sh_type)) { 218 case SHT_SYMTAB: 219 if (symtabshdr != NULL) 220 weird = 1; 221 symtabshdr = &shdrp[i]; 222 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 223 break; 224 case SHT_RELA: 225 tmpl = xmalloc(sizeof *tmpl, fn, "rela list element"); 226 if (tmpl == NULL) 227 goto bad; 228 tmpl->mem = NULL; 229 tmpl->file = xewtoh(shdrp[i].sh_offset); 230 tmpl->size = xewtoh(shdrp[i].sh_size); 231 tmpl->next = relalist; 232 relalist = tmpl; 233 break; 234 case SHT_REL: 235 tmpl = xmalloc(sizeof *tmpl, fn, "rel list element"); 236 if (tmpl == NULL) 237 goto bad; 238 tmpl->mem = NULL; 239 tmpl->file = xewtoh(shdrp[i].sh_offset); 240 tmpl->size = xewtoh(shdrp[i].sh_size); 241 tmpl->next = rellist; 242 rellist = tmpl; 243 break; 244 } 245 } 246 if (symtabshdr == NULL) 247 goto out; 248 if (strtabshdr == NULL) 249 weird = 1; 250 if (weird) { 251 fprintf(stderr, "%s: weird executable (unsupported)\n", fn); 252 goto bad; 253 } 254 255 /* 256 * load up everything we need 257 */ 258 259 /* symbol table */ 260 if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table")) 261 == NULL) 262 goto bad; 263 if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 264 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 265 goto bad; 266 267 /* string table */ 268 if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table")) 269 == NULL) 270 goto bad; 271 if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset), 272 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 273 goto bad; 274 275 /* any rela tables */ 276 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 277 if ((tmpl->mem = xmalloc(tmpl->size, fn, "rela table")) 278 == NULL) 279 goto bad; 280 if (xreadatoff(fd, tmpl->mem, tmpl->file, 281 tmpl->size, fn) != tmpl->size) 282 goto bad; 283 } 284 285 /* any rel tables */ 286 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 287 if ((tmpl->mem = xmalloc(tmpl->size, fn, "rel table")) 288 == NULL) 289 goto bad; 290 if (xreadatoff(fd, tmpl->mem, tmpl->file, 291 tmpl->size, fn) != tmpl->size) 292 goto bad; 293 } 294 295 /* Prepare data structures for symbol movement. */ 296 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 297 nlocalsyms = xe32toh(symtabshdr->sh_info); 298 if ((symfwmap = xmalloc(nsyms * sizeof (Elf_Size), fn, 299 "symbol forward mapping table")) == NULL) 300 goto bad; 301 if ((symrvmap = xmalloc(nsyms * sizeof (Elf_Size), fn, 302 "symbol reverse mapping table")) == NULL) 303 goto bad; 304 305 /* init location -> symbol # table */ 306 for (ewi = 0; ewi < nsyms; ewi++) 307 symrvmap[ewi] = ewi; 308 309 /* move symbols, making them local */ 310 for (ewi = nlocalsyms; ewi < nsyms; ewi++) { 311 Elf_Sym *sp, symswap; 312 Elf_Size mapswap; 313 314 sp = &symtabp[ewi]; 315 316 /* if it's on our keep list, don't move it */ 317 if (in_keep_list(strtabp + xe32toh(sp->st_name))) 318 continue; 319 320 /* if it's an undefined symbol, keep it */ 321 if (xe16toh(sp->st_shndx) == SHN_UNDEF) 322 continue; 323 324 /* adjust the symbol so that it's local */ 325 sp->st_info = 326 ELF_ST_INFO(STB_LOCAL, sp->st_info); 327 /* (STB_LOCAL << 4) | ELF_SYM_TYPE(sp->st_info); *//* XXX */ 328 329 /* 330 * move the symbol to its new location 331 */ 332 333 /* note that symbols in those locations have been swapped */ 334 mapswap = symrvmap[ewi]; 335 symrvmap[ewi] = symrvmap[nlocalsyms]; 336 symrvmap[nlocalsyms] = mapswap; 337 338 /* and swap the symbols */ 339 symswap = *sp; 340 *sp = symtabp[nlocalsyms]; 341 symtabp[nlocalsyms] = symswap; 342 343 nlocalsyms++; /* note new local sym */ 344 } 345 symtabshdr->sh_info = htoxe32(nlocalsyms); 346 347 /* set up symbol # -> location mapping table */ 348 for (ewi = 0; ewi < nsyms; ewi++) 349 symfwmap[symrvmap[ewi]] = ewi; 350 351 /* any rela tables */ 352 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 353 Elf_Rela *relap = tmpl->mem; 354 355 for (ewi = 0; ewi < tmpl->size / sizeof(*relap); ewi++) { 356 relap[ewi].r_info = htoxew(ELF_R_INFO( 357 symfwmap[ELF_R_SYM(xewtoh(relap[ewi].r_info))], 358 ELF_R_TYPE(xewtoh(relap[ewi].r_info)) 359 )); 360 } 361 } 362 363 /* any rel tables */ 364 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 365 Elf_Rel *relp = tmpl->mem; 366 367 for (ewi = 0; ewi < tmpl->size / sizeof *relp; ewi++) { 368 relp[ewi].r_info = htoxew(ELF_R_INFO( 369 symfwmap[ELF_R_SYM(xewtoh(relp[ewi].r_info))], 370 ELF_R_TYPE(xewtoh(relp[ewi].r_info)) 371 )); 372 } 373 } 374 375 /* 376 * write new tables to the file 377 */ 378 if (xwriteatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 379 shdrsize) 380 goto bad; 381 if (xwriteatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 382 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 383 goto bad; 384 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 385 if (xwriteatoff(fd, tmpl->mem, tmpl->file, 386 tmpl->size, fn) != tmpl->size) 387 goto bad; 388 } 389 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 390 if (xwriteatoff(fd, tmpl->mem, tmpl->file, 391 tmpl->size, fn) != tmpl->size) 392 goto bad; 393 } 394 395 out: 396 if (shdrp != NULL) 397 free(shdrp); 398 if (symtabp != NULL) 399 free(symtabp); 400 if (strtabp != NULL) 401 free(strtabp); 402 if (symfwmap != NULL) 403 free(symfwmap); 404 if (symrvmap != NULL) 405 free(symrvmap); 406 while ((tmpl = relalist) != NULL) { 407 relalist = tmpl->next; 408 if (tmpl->mem != NULL) 409 free(tmpl->mem); 410 free(tmpl); 411 } 412 while ((tmpl = rellist) != NULL) { 413 rellist = tmpl->next; 414 if (tmpl->mem != NULL) 415 free(tmpl->mem); 416 free(tmpl); 417 } 418 return (rv); 419 420 bad: 421 rv = 1; 422 goto out; 423 } 424 425 #endif /* include this size of ELF */ 426