1 /* 2 * Copyright (c) 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char sccsid[] = "@(#)nlist.c 8.1 (Berkeley) 6/4/93"; 32 #endif /* LIBC_SCCS and not lint */ 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include "namespace.h" 37 #include <sys/param.h> 38 #include <sys/mman.h> 39 #include <sys/stat.h> 40 #include <sys/file.h> 41 #include <arpa/inet.h> 42 43 #include <errno.h> 44 #include <a.out.h> 45 #include <stdio.h> 46 #include <string.h> 47 #include <unistd.h> 48 #include "un-namespace.h" 49 50 #define _NLIST_DO_AOUT 51 #define _NLIST_DO_ELF 52 53 #ifdef _NLIST_DO_ELF 54 #include <machine/elf.h> 55 #include <elf-hints.h> 56 #endif 57 58 int __fdnlist(int, struct nlist *); 59 int __aout_fdnlist(int, struct nlist *); 60 int __elf_fdnlist(int, struct nlist *); 61 62 int 63 nlist(name, list) 64 const char *name; 65 struct nlist *list; 66 { 67 int fd, n; 68 69 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 70 if (fd < 0) 71 return (-1); 72 n = __fdnlist(fd, list); 73 (void)_close(fd); 74 return (n); 75 } 76 77 static struct nlist_handlers { 78 int (*fn)(int fd, struct nlist *list); 79 } nlist_fn[] = { 80 #ifdef _NLIST_DO_AOUT 81 { __aout_fdnlist }, 82 #endif 83 #ifdef _NLIST_DO_ELF 84 { __elf_fdnlist }, 85 #endif 86 }; 87 88 int 89 __fdnlist(fd, list) 90 int fd; 91 struct nlist *list; 92 { 93 int n = -1, i; 94 95 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) { 96 n = (nlist_fn[i].fn)(fd, list); 97 if (n != -1) 98 break; 99 } 100 return (n); 101 } 102 103 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 104 105 #ifdef _NLIST_DO_AOUT 106 int 107 __aout_fdnlist(fd, list) 108 int fd; 109 struct nlist *list; 110 { 111 struct nlist *p, *symtab; 112 caddr_t strtab, a_out_mmap; 113 off_t stroff, symoff; 114 u_long symsize; 115 int nent; 116 struct exec * exec; 117 struct stat st; 118 119 /* check that file is at least as large as struct exec! */ 120 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 121 return (-1); 122 123 /* Check for files too large to mmap. */ 124 if (st.st_size > SIZE_T_MAX) { 125 errno = EFBIG; 126 return (-1); 127 } 128 129 /* 130 * Map the whole a.out file into our address space. 131 * We then find the string table withing this area. 132 * We do not just mmap the string table, as it probably 133 * does not start at a page boundary - we save ourselves a 134 * lot of nastiness by mmapping the whole file. 135 * 136 * This gives us an easy way to randomly access all the strings, 137 * without making the memory allocation permanent as with 138 * malloc/free (i.e., munmap will return it to the system). 139 */ 140 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 141 if (a_out_mmap == MAP_FAILED) 142 return (-1); 143 144 exec = (struct exec *)a_out_mmap; 145 if (N_BADMAG(*exec)) { 146 munmap(a_out_mmap, (size_t)st.st_size); 147 return (-1); 148 } 149 150 symoff = N_SYMOFF(*exec); 151 symsize = exec->a_syms; 152 stroff = symoff + symsize; 153 154 /* find the string table in our mmapped area */ 155 strtab = a_out_mmap + stroff; 156 symtab = (struct nlist *)(a_out_mmap + symoff); 157 158 /* 159 * clean out any left-over information for all valid entries. 160 * Type and value defined to be 0 if not found; historical 161 * versions cleared other and desc as well. Also figure out 162 * the largest string length so don't read any more of the 163 * string table than we have to. 164 * 165 * XXX clearing anything other than n_type and n_value violates 166 * the semantics given in the man page. 167 */ 168 nent = 0; 169 for (p = list; !ISLAST(p); ++p) { 170 p->n_type = 0; 171 p->n_other = 0; 172 p->n_desc = 0; 173 p->n_value = 0; 174 ++nent; 175 } 176 177 while (symsize > 0) { 178 int soff; 179 180 symsize-= sizeof(struct nlist); 181 soff = symtab->n_un.n_strx; 182 183 184 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 185 for (p = list; !ISLAST(p); p++) 186 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 187 p->n_value = symtab->n_value; 188 p->n_type = symtab->n_type; 189 p->n_desc = symtab->n_desc; 190 p->n_other = symtab->n_other; 191 if (--nent <= 0) 192 break; 193 } 194 symtab++; 195 } 196 munmap(a_out_mmap, (size_t)st.st_size); 197 return (nent); 198 } 199 #endif 200 201 #ifdef _NLIST_DO_ELF 202 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 203 204 /* 205 * __elf_is_okay__ - Determine if ehdr really 206 * is ELF and valid for the target platform. 207 * 208 * WARNING: This is NOT an ELF ABI function and 209 * as such its use should be restricted. 210 */ 211 int 212 __elf_is_okay__(Elf_Ehdr *ehdr) 213 { 214 int retval = 0; 215 /* 216 * We need to check magic, class size, endianess, 217 * and version before we look at the rest of the 218 * Elf_Ehdr structure. These few elements are 219 * represented in a machine independant fashion. 220 */ 221 if (IS_ELF(*ehdr) && 222 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 223 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 224 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 225 226 /* Now check the machine dependant header */ 227 if (ehdr->e_machine == ELF_TARG_MACH && 228 ehdr->e_version == ELF_TARG_VER) 229 retval = 1; 230 } 231 return retval; 232 } 233 234 int 235 __elf_fdnlist(fd, list) 236 int fd; 237 struct nlist *list; 238 { 239 struct nlist *p; 240 Elf_Off symoff = 0, symstroff = 0; 241 Elf_Size symsize = 0, symstrsize = 0; 242 Elf_Ssize cc, i; 243 int nent = -1; 244 int errsave; 245 Elf_Sym sbuf[1024]; 246 Elf_Sym *s; 247 Elf_Ehdr ehdr; 248 char *strtab = NULL; 249 Elf_Shdr *shdr = NULL; 250 Elf_Size shdr_size; 251 void *base; 252 struct stat st; 253 254 /* Make sure obj is OK */ 255 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 256 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 257 !__elf_is_okay__(&ehdr) || 258 _fstat(fd, &st) < 0) 259 return (-1); 260 261 /* calculate section header table size */ 262 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 263 264 /* Make sure it's not too big to mmap */ 265 if (shdr_size > SIZE_T_MAX) { 266 errno = EFBIG; 267 return (-1); 268 } 269 270 /* mmap section header table */ 271 base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd, 272 (off_t)ehdr.e_shoff); 273 if (base == MAP_FAILED) 274 return (-1); 275 shdr = (Elf_Shdr *)base; 276 277 /* 278 * Find the symbol table entry and it's corresponding 279 * string table entry. Version 1.1 of the ABI states 280 * that there is only one symbol table but that this 281 * could change in the future. 282 */ 283 for (i = 0; i < ehdr.e_shnum; i++) { 284 if (shdr[i].sh_type == SHT_SYMTAB) { 285 symoff = shdr[i].sh_offset; 286 symsize = shdr[i].sh_size; 287 symstroff = shdr[shdr[i].sh_link].sh_offset; 288 symstrsize = shdr[shdr[i].sh_link].sh_size; 289 break; 290 } 291 } 292 293 /* Check for files too large to mmap. */ 294 if (symstrsize > SIZE_T_MAX) { 295 errno = EFBIG; 296 goto done; 297 } 298 /* 299 * Map string table into our address space. This gives us 300 * an easy way to randomly access all the strings, without 301 * making the memory allocation permanent as with malloc/free 302 * (i.e., munmap will return it to the system). 303 */ 304 base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd, 305 (off_t)symstroff); 306 if (base == MAP_FAILED) 307 goto done; 308 strtab = (char *)base; 309 310 /* 311 * clean out any left-over information for all valid entries. 312 * Type and value defined to be 0 if not found; historical 313 * versions cleared other and desc as well. Also figure out 314 * the largest string length so don't read any more of the 315 * string table than we have to. 316 * 317 * XXX clearing anything other than n_type and n_value violates 318 * the semantics given in the man page. 319 */ 320 nent = 0; 321 for (p = list; !ISLAST(p); ++p) { 322 p->n_type = 0; 323 p->n_other = 0; 324 p->n_desc = 0; 325 p->n_value = 0; 326 ++nent; 327 } 328 329 /* Don't process any further if object is stripped. */ 330 if (symoff == 0) 331 goto done; 332 333 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 334 nent = -1; 335 goto done; 336 } 337 338 while (symsize > 0 && nent > 0) { 339 cc = MIN(symsize, sizeof(sbuf)); 340 if (_read(fd, sbuf, cc) != cc) 341 break; 342 symsize -= cc; 343 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 344 char *name; 345 struct nlist *p; 346 347 name = strtab + s->st_name; 348 if (name[0] == '\0') 349 continue; 350 for (p = list; !ISLAST(p); p++) { 351 if ((p->n_un.n_name[0] == '_' && 352 strcmp(name, p->n_un.n_name+1) == 0) 353 || strcmp(name, p->n_un.n_name) == 0) { 354 elf_sym_to_nlist(p, s, shdr, 355 ehdr.e_shnum); 356 if (--nent <= 0) 357 break; 358 } 359 } 360 } 361 } 362 done: 363 errsave = errno; 364 if (strtab != NULL) 365 munmap(strtab, symstrsize); 366 if (shdr != NULL) 367 munmap(shdr, shdr_size); 368 errno = errsave; 369 return (nent); 370 } 371 372 /* 373 * Convert an Elf_Sym into an nlist structure. This fills in only the 374 * n_value and n_type members. 375 */ 376 static void 377 elf_sym_to_nlist(nl, s, shdr, shnum) 378 struct nlist *nl; 379 Elf_Sym *s; 380 Elf_Shdr *shdr; 381 int shnum; 382 { 383 nl->n_value = s->st_value; 384 385 switch (s->st_shndx) { 386 case SHN_UNDEF: 387 case SHN_COMMON: 388 nl->n_type = N_UNDF; 389 break; 390 case SHN_ABS: 391 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 392 N_FN : N_ABS; 393 break; 394 default: 395 if (s->st_shndx >= shnum) 396 nl->n_type = N_UNDF; 397 else { 398 Elf_Shdr *sh = shdr + s->st_shndx; 399 400 nl->n_type = sh->sh_type == SHT_PROGBITS ? 401 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 402 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 403 } 404 break; 405 } 406 407 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 408 ELF_ST_BIND(s->st_info) == STB_WEAK) 409 nl->n_type |= N_EXT; 410 } 411 #endif /* _NLIST_DO_ELF */ 412