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 $"); 35 #endif 36 static const char rcsid[] = 37 "$FreeBSD$"; 38 #endif 39 40 #ifndef ELFSIZE 41 #define ELFSIZE 32 42 #endif 43 44 #include <sys/types.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 "endian.h" 54 #include "extern.h" 55 56 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 57 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 58 59 #define __ELF_WORD_SIZE ELFSIZE 60 #if (ELFSIZE == 32) 61 #include <sys/elf32.h> 62 #define xewtoh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 63 #elif (ELFSIZE == 64) 64 #include <sys/elf64.h> 65 #define xewtoh(x) ((data == ELFDATA2MSB) ? be64toh(x) : le64toh(x)) 66 #endif 67 #include <sys/elf_generic.h> 68 69 #define CONCAT(x,y) __CONCAT(x,y) 70 #define ELFNAME(x) CONCAT(elf,CONCAT(ELFSIZE,CONCAT(_,x))) 71 #define ELFNAME2(x,y) CONCAT(x,CONCAT(_elf,CONCAT(ELFSIZE,CONCAT(_,y)))) 72 #define ELFNAMEEND(x) CONCAT(x,CONCAT(_elf,ELFSIZE)) 73 #define ELFDEFNNAME(x) CONCAT(ELF,CONCAT(ELFSIZE,CONCAT(_,x))) 74 75 #define xe16toh(x) ((data == ELFDATA2MSB) ? be16toh(x) : le16toh(x)) 76 #define xe32toh(x) ((data == ELFDATA2MSB) ? be32toh(x) : le32toh(x)) 77 #define htoxe32(x) ((data == ELFDATA2MSB) ? htobe32(x) : htole32(x)) 78 79 struct listelem { 80 struct listelem *next; 81 void *mem; 82 off_t file; 83 size_t size; 84 }; 85 86 static ssize_t 87 xreadatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 88 { 89 ssize_t rv; 90 91 if (lseek(fd, off, SEEK_SET) != off) { 92 perror(fn); 93 return -1; 94 } 95 if ((rv = read(fd, buf, size)) != size) { 96 fprintf(stderr, "%s: read error: %s\n", fn, 97 rv == -1 ? strerror(errno) : "short read"); 98 return -1; 99 } 100 return size; 101 } 102 103 static ssize_t 104 xwriteatoff(int fd, void *buf, off_t off, size_t size, const char *fn) 105 { 106 ssize_t rv; 107 108 if (lseek(fd, off, SEEK_SET) != off) { 109 perror(fn); 110 return -1; 111 } 112 if ((rv = write(fd, buf, size)) != size) { 113 fprintf(stderr, "%s: write error: %s\n", fn, 114 rv == -1 ? strerror(errno) : "short write"); 115 return -1; 116 } 117 return size; 118 } 119 120 static void * 121 xmalloc(size_t size, const char *fn, const char *use) 122 { 123 void *rv; 124 125 rv = malloc(size); 126 if (rv == NULL) 127 fprintf(stderr, "%s: out of memory (allocating for %s)\n", 128 fn, use); 129 return (rv); 130 } 131 132 int 133 ELFNAMEEND(check)(int fd, const char *fn) 134 { 135 Elf_Ehdr eh; 136 struct stat sb; 137 unsigned char data; 138 139 /* 140 * Check the header to maek sure it's an ELF file (of the 141 * appropriate size). 142 */ 143 if (fstat(fd, &sb) == -1) 144 return 0; 145 if (sb.st_size < sizeof eh) 146 return 0; 147 if (read(fd, &eh, sizeof eh) != sizeof eh) 148 return 0; 149 150 if (IS_ELF(eh) == 0) 151 return 0; 152 153 data = eh.e_ident[EI_DATA]; 154 155 switch (xe16toh(eh.e_machine)) { 156 case EM_386: break; 157 case EM_ALPHA: break; 158 case EM_IA_64: break; 159 case EM_SPARCV9: break; 160 /* ELFDEFNNAME(MACHDEP_ID_CASES) */ 161 162 default: 163 return 0; 164 } 165 166 return 1; 167 } 168 169 int 170 ELFNAMEEND(hide)(int fd, const char *fn) 171 { 172 Elf_Ehdr ehdr; 173 Elf_Shdr *shdrp = NULL, *symtabshdr, *strtabshdr; 174 Elf_Sym *symtabp = NULL; 175 char *strtabp = NULL; 176 Elf_Word *symfwmap = NULL, *symrvmap = NULL, nsyms, nlocalsyms, ewi; 177 struct listelem *relalist = NULL, *rellist = NULL, *tmpl; 178 ssize_t shdrsize; 179 int rv, i, weird; 180 unsigned char data; 181 182 rv = 0; 183 if (xreadatoff(fd, &ehdr, 0, sizeof ehdr, fn) != sizeof ehdr) 184 goto bad; 185 186 data = ehdr.e_ident[EI_DATA]; 187 188 shdrsize = xe16toh(ehdr.e_shnum) * xe16toh(ehdr.e_shentsize); 189 if ((shdrp = xmalloc(shdrsize, fn, "section header table")) == NULL) 190 goto bad; 191 if (xreadatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 192 shdrsize) 193 goto bad; 194 195 symtabshdr = strtabshdr = NULL; 196 weird = 0; 197 for (i = 0; i < xe16toh(ehdr.e_shnum); i++) { 198 switch (xe32toh(shdrp[i].sh_type)) { 199 case SHT_SYMTAB: 200 if (symtabshdr != NULL) 201 weird = 1; 202 symtabshdr = &shdrp[i]; 203 strtabshdr = &shdrp[xe32toh(shdrp[i].sh_link)]; 204 break; 205 case SHT_RELA: 206 tmpl = xmalloc(sizeof *tmpl, fn, "rela list element"); 207 if (tmpl == NULL) 208 goto bad; 209 tmpl->mem = NULL; 210 tmpl->file = shdrp[i].sh_offset; 211 tmpl->size = shdrp[i].sh_size; 212 tmpl->next = relalist; 213 relalist = tmpl; 214 break; 215 case SHT_REL: 216 tmpl = xmalloc(sizeof *tmpl, fn, "rel list element"); 217 if (tmpl == NULL) 218 goto bad; 219 tmpl->mem = NULL; 220 tmpl->file = shdrp[i].sh_offset; 221 tmpl->size = shdrp[i].sh_size; 222 tmpl->next = rellist; 223 rellist = tmpl; 224 break; 225 } 226 } 227 if (symtabshdr == NULL) 228 goto out; 229 if (strtabshdr == NULL) 230 weird = 1; 231 if (weird) { 232 fprintf(stderr, "%s: weird executable (unsupported)\n", fn); 233 goto bad; 234 } 235 236 /* 237 * load up everything we need 238 */ 239 240 /* symbol table */ 241 if ((symtabp = xmalloc(xewtoh(symtabshdr->sh_size), fn, "symbol table")) 242 == NULL) 243 goto bad; 244 if (xreadatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 245 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 246 goto bad; 247 248 /* string table */ 249 if ((strtabp = xmalloc(xewtoh(strtabshdr->sh_size), fn, "string table")) 250 == NULL) 251 goto bad; 252 if (xreadatoff(fd, strtabp, xewtoh(strtabshdr->sh_offset), 253 xewtoh(strtabshdr->sh_size), fn) != xewtoh(strtabshdr->sh_size)) 254 goto bad; 255 256 /* any rela tables */ 257 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 258 if ((tmpl->mem = xmalloc(xewtoh(tmpl->size), fn, "rela table")) 259 == NULL) 260 goto bad; 261 if (xreadatoff(fd, tmpl->mem, xewtoh(tmpl->file), 262 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 263 goto bad; 264 } 265 266 /* any rel tables */ 267 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 268 if ((tmpl->mem = xmalloc(xewtoh(tmpl->size), fn, "rel table")) 269 == NULL) 270 goto bad; 271 if (xreadatoff(fd, tmpl->mem, xewtoh(tmpl->file), 272 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 273 goto bad; 274 } 275 276 /* Prepare data structures for symbol movement. */ 277 nsyms = xewtoh(symtabshdr->sh_size) / xewtoh(symtabshdr->sh_entsize); 278 nlocalsyms = xe32toh(symtabshdr->sh_info); 279 if ((symfwmap = xmalloc(nsyms * sizeof (Elf_Word), fn, 280 "symbol forward mapping table")) == NULL) 281 goto bad; 282 if ((symrvmap = xmalloc(nsyms * sizeof (Elf_Word), fn, 283 "symbol reverse mapping table")) == NULL) 284 goto bad; 285 286 /* init location -> symbol # table */ 287 for (ewi = 0; ewi < nsyms; ewi++) 288 symrvmap[ewi] = ewi; 289 290 /* move symbols, making them local */ 291 for (ewi = nlocalsyms; ewi < nsyms; ewi++) { 292 Elf_Sym *sp, symswap; 293 Elf_Word mapswap; 294 295 sp = &symtabp[ewi]; 296 297 /* if it's on our keep list, don't move it */ 298 if (in_keep_list(strtabp + xe32toh(sp->st_name))) 299 continue; 300 301 /* if it's an undefined symbol, keep it */ 302 if (xe16toh(sp->st_shndx) == SHN_UNDEF) 303 continue; 304 305 /* adjust the symbol so that it's local */ 306 sp->st_info = 307 ELF_ST_INFO(STB_LOCAL, sp->st_info); 308 /* (STB_LOCAL << 4) | ELF_SYM_TYPE(sp->st_info); *//* XXX */ 309 310 /* 311 * move the symbol to its new location 312 */ 313 314 /* note that symbols in those locations have been swapped */ 315 mapswap = symrvmap[ewi]; 316 symrvmap[ewi] = symrvmap[nlocalsyms]; 317 symrvmap[nlocalsyms] = mapswap; 318 319 /* and swap the symbols */ 320 symswap = *sp; 321 *sp = symtabp[nlocalsyms]; 322 symtabp[nlocalsyms] = symswap; 323 324 nlocalsyms++; /* note new local sym */ 325 } 326 symtabshdr->sh_info = htoxe32(nlocalsyms); 327 328 /* set up symbol # -> location mapping table */ 329 for (ewi = 0; ewi < nsyms; ewi++) 330 symfwmap[symrvmap[ewi]] = ewi; 331 332 /* any rela tables */ 333 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 334 Elf_Rela *relap = tmpl->mem; 335 336 for (ewi = 0; ewi < xewtoh(tmpl->size) / sizeof(*relap); ewi++) { 337 relap[ewi].r_info = 338 #if (ELFSIZE == 32) /* XXX */ 339 symfwmap[ELF_R_SYM(xe32toh(relap[ewi].r_info))] << 8 | 340 ELF_R_TYPE(xe32toh(relap[ewi].r_info)); 341 #elif (ELFSIZE == 64) /* XXX */ 342 symfwmap[ELF_R_SYM(xewtoh(relap[ewi].r_info))] << 32 | 343 ELF_R_TYPE(xewtoh(relap[ewi].r_info)); 344 #endif /* XXX */ 345 } 346 } 347 348 /* any rel tables */ 349 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 350 Elf_Rel *relp = tmpl->mem; 351 352 for (ewi = 0; ewi < xewtoh(tmpl->size) / sizeof *relp; ewi++) { 353 relp[ewi].r_info = 354 #if (ELFSIZE == 32) /* XXX */ 355 symfwmap[ELF_R_SYM(xe32toh(relp[ewi].r_info))] << 8 | 356 ELF_R_TYPE(xe32toh(relp[ewi].r_info)); 357 #elif (ELFSIZE == 64) /* XXX */ 358 symfwmap[ELF_R_SYM(xewtoh(relp[ewi].r_info))] << 32 | 359 ELF_R_TYPE(xewtoh(relp[ewi].r_info)); 360 #endif /* XXX */ 361 } 362 } 363 364 /* 365 * write new tables to the file 366 */ 367 if (xwriteatoff(fd, shdrp, xewtoh(ehdr.e_shoff), shdrsize, fn) != 368 shdrsize) 369 goto bad; 370 if (xwriteatoff(fd, symtabp, xewtoh(symtabshdr->sh_offset), 371 xewtoh(symtabshdr->sh_size), fn) != xewtoh(symtabshdr->sh_size)) 372 goto bad; 373 for (tmpl = relalist; tmpl != NULL; tmpl = tmpl->next) { 374 if (xwriteatoff(fd, tmpl->mem, xewtoh(tmpl->file), 375 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 376 goto bad; 377 } 378 for (tmpl = rellist; tmpl != NULL; tmpl = tmpl->next) { 379 if (xwriteatoff(fd, tmpl->mem, xewtoh(tmpl->file), 380 xewtoh(tmpl->size), fn) != xewtoh(tmpl->size)) 381 goto bad; 382 } 383 384 out: 385 if (shdrp != NULL) 386 free(shdrp); 387 if (symtabp != NULL) 388 free(symtabp); 389 if (strtabp != NULL) 390 free(strtabp); 391 if (symfwmap != NULL) 392 free(symfwmap); 393 if (symrvmap != NULL) 394 free(symrvmap); 395 while ((tmpl = relalist) != NULL) { 396 relalist = tmpl->next; 397 if (tmpl->mem != NULL) 398 free(tmpl->mem); 399 free(tmpl); 400 } 401 while ((tmpl = rellist) != NULL) { 402 rellist = tmpl->next; 403 if (tmpl->mem != NULL) 404 free(tmpl->mem); 405 free(tmpl); 406 } 407 return (rv); 408 409 bad: 410 rv = 1; 411 goto out; 412 } 413 414 #endif /* include this size of ELF */ 415