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 /* There is no a.out support on arm64 */ 51 #ifndef __aarch64__ 52 #define _NLIST_DO_AOUT 53 #endif 54 #define _NLIST_DO_ELF 55 56 #ifdef _NLIST_DO_ELF 57 #include <machine/elf.h> 58 #include <elf-hints.h> 59 #endif 60 61 int __fdnlist(int, struct nlist *); 62 int __aout_fdnlist(int, struct nlist *); 63 int __elf_fdnlist(int, struct nlist *); 64 65 int 66 nlist(name, list) 67 const char *name; 68 struct nlist *list; 69 { 70 int fd, n; 71 72 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 73 if (fd < 0) 74 return (-1); 75 n = __fdnlist(fd, list); 76 (void)_close(fd); 77 return (n); 78 } 79 80 static struct nlist_handlers { 81 int (*fn)(int fd, struct nlist *list); 82 } nlist_fn[] = { 83 #ifdef _NLIST_DO_AOUT 84 { __aout_fdnlist }, 85 #endif 86 #ifdef _NLIST_DO_ELF 87 { __elf_fdnlist }, 88 #endif 89 }; 90 91 int 92 __fdnlist(fd, list) 93 int fd; 94 struct nlist *list; 95 { 96 int n = -1, i; 97 98 for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) { 99 n = (nlist_fn[i].fn)(fd, list); 100 if (n != -1) 101 break; 102 } 103 return (n); 104 } 105 106 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 107 108 #ifdef _NLIST_DO_AOUT 109 int 110 __aout_fdnlist(fd, list) 111 int fd; 112 struct nlist *list; 113 { 114 struct nlist *p, *symtab; 115 caddr_t strtab, a_out_mmap; 116 off_t stroff, symoff; 117 u_long symsize; 118 int nent; 119 struct exec * exec; 120 struct stat st; 121 122 /* check that file is at least as large as struct exec! */ 123 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 124 return (-1); 125 126 /* Check for files too large to mmap. */ 127 if (st.st_size > SIZE_T_MAX) { 128 errno = EFBIG; 129 return (-1); 130 } 131 132 /* 133 * Map the whole a.out file into our address space. 134 * We then find the string table withing this area. 135 * We do not just mmap the string table, as it probably 136 * does not start at a page boundary - we save ourselves a 137 * lot of nastiness by mmapping the whole file. 138 * 139 * This gives us an easy way to randomly access all the strings, 140 * without making the memory allocation permanent as with 141 * malloc/free (i.e., munmap will return it to the system). 142 */ 143 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 144 if (a_out_mmap == MAP_FAILED) 145 return (-1); 146 147 exec = (struct exec *)a_out_mmap; 148 if (N_BADMAG(*exec)) { 149 munmap(a_out_mmap, (size_t)st.st_size); 150 return (-1); 151 } 152 153 symoff = N_SYMOFF(*exec); 154 symsize = exec->a_syms; 155 stroff = symoff + symsize; 156 157 /* find the string table in our mmapped area */ 158 strtab = a_out_mmap + stroff; 159 symtab = (struct nlist *)(a_out_mmap + symoff); 160 161 /* 162 * clean out any left-over information for all valid entries. 163 * Type and value defined to be 0 if not found; historical 164 * versions cleared other and desc as well. Also figure out 165 * the largest string length so don't read any more of the 166 * string table than we have to. 167 * 168 * XXX clearing anything other than n_type and n_value violates 169 * the semantics given in the man page. 170 */ 171 nent = 0; 172 for (p = list; !ISLAST(p); ++p) { 173 p->n_type = 0; 174 p->n_other = 0; 175 p->n_desc = 0; 176 p->n_value = 0; 177 ++nent; 178 } 179 180 while (symsize > 0) { 181 int soff; 182 183 symsize-= sizeof(struct nlist); 184 soff = symtab->n_un.n_strx; 185 186 187 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 188 for (p = list; !ISLAST(p); p++) 189 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 190 p->n_value = symtab->n_value; 191 p->n_type = symtab->n_type; 192 p->n_desc = symtab->n_desc; 193 p->n_other = symtab->n_other; 194 if (--nent <= 0) 195 break; 196 } 197 symtab++; 198 } 199 munmap(a_out_mmap, (size_t)st.st_size); 200 return (nent); 201 } 202 #endif 203 204 #ifdef _NLIST_DO_ELF 205 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 206 207 /* 208 * __elf_is_okay__ - Determine if ehdr really 209 * is ELF and valid for the target platform. 210 * 211 * WARNING: This is NOT an ELF ABI function and 212 * as such its use should be restricted. 213 */ 214 int 215 __elf_is_okay__(Elf_Ehdr *ehdr) 216 { 217 int retval = 0; 218 /* 219 * We need to check magic, class size, endianess, 220 * and version before we look at the rest of the 221 * Elf_Ehdr structure. These few elements are 222 * represented in a machine independant fashion. 223 */ 224 if (IS_ELF(*ehdr) && 225 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 226 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 227 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 228 229 /* Now check the machine dependant header */ 230 if (ehdr->e_machine == ELF_TARG_MACH && 231 ehdr->e_version == ELF_TARG_VER) 232 retval = 1; 233 } 234 return retval; 235 } 236 237 int 238 __elf_fdnlist(fd, list) 239 int fd; 240 struct nlist *list; 241 { 242 struct nlist *p; 243 Elf_Off symoff = 0, symstroff = 0; 244 Elf_Size symsize = 0, symstrsize = 0; 245 Elf_Ssize cc, i; 246 int nent = -1; 247 int errsave; 248 Elf_Sym sbuf[1024]; 249 Elf_Sym *s; 250 Elf_Ehdr ehdr; 251 char *strtab = NULL; 252 Elf_Shdr *shdr = NULL; 253 Elf_Size shdr_size; 254 void *base; 255 struct stat st; 256 257 /* Make sure obj is OK */ 258 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 259 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 260 !__elf_is_okay__(&ehdr) || 261 _fstat(fd, &st) < 0) 262 return (-1); 263 264 /* calculate section header table size */ 265 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 266 267 /* Make sure it's not too big to mmap */ 268 if (shdr_size > SIZE_T_MAX) { 269 errno = EFBIG; 270 return (-1); 271 } 272 273 /* mmap section header table */ 274 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 275 (off_t)ehdr.e_shoff); 276 if (base == MAP_FAILED) 277 return (-1); 278 shdr = (Elf_Shdr *)base; 279 280 /* 281 * Find the symbol table entry and it's corresponding 282 * string table entry. Version 1.1 of the ABI states 283 * that there is only one symbol table but that this 284 * could change in the future. 285 */ 286 for (i = 0; i < ehdr.e_shnum; i++) { 287 if (shdr[i].sh_type == SHT_SYMTAB) { 288 symoff = shdr[i].sh_offset; 289 symsize = shdr[i].sh_size; 290 symstroff = shdr[shdr[i].sh_link].sh_offset; 291 symstrsize = shdr[shdr[i].sh_link].sh_size; 292 break; 293 } 294 } 295 296 /* Check for files too large to mmap. */ 297 if (symstrsize > SIZE_T_MAX) { 298 errno = EFBIG; 299 goto done; 300 } 301 /* 302 * Map string table into our address space. This gives us 303 * an easy way to randomly access all the strings, without 304 * making the memory allocation permanent as with malloc/free 305 * (i.e., munmap will return it to the system). 306 */ 307 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 308 (off_t)symstroff); 309 if (base == MAP_FAILED) 310 goto done; 311 strtab = (char *)base; 312 313 /* 314 * clean out any left-over information for all valid entries. 315 * Type and value defined to be 0 if not found; historical 316 * versions cleared other and desc as well. Also figure out 317 * the largest string length so don't read any more of the 318 * string table than we have to. 319 * 320 * XXX clearing anything other than n_type and n_value violates 321 * the semantics given in the man page. 322 */ 323 nent = 0; 324 for (p = list; !ISLAST(p); ++p) { 325 p->n_type = 0; 326 p->n_other = 0; 327 p->n_desc = 0; 328 p->n_value = 0; 329 ++nent; 330 } 331 332 /* Don't process any further if object is stripped. */ 333 if (symoff == 0) 334 goto done; 335 336 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 337 nent = -1; 338 goto done; 339 } 340 341 while (symsize > 0 && nent > 0) { 342 cc = MIN(symsize, sizeof(sbuf)); 343 if (_read(fd, sbuf, cc) != cc) 344 break; 345 symsize -= cc; 346 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 347 char *name; 348 struct nlist *p; 349 350 name = strtab + s->st_name; 351 if (name[0] == '\0') 352 continue; 353 for (p = list; !ISLAST(p); p++) { 354 if ((p->n_un.n_name[0] == '_' && 355 strcmp(name, p->n_un.n_name+1) == 0) 356 || strcmp(name, p->n_un.n_name) == 0) { 357 elf_sym_to_nlist(p, s, shdr, 358 ehdr.e_shnum); 359 if (--nent <= 0) 360 break; 361 } 362 } 363 } 364 } 365 done: 366 errsave = errno; 367 if (strtab != NULL) 368 munmap(strtab, symstrsize); 369 if (shdr != NULL) 370 munmap(shdr, shdr_size); 371 errno = errsave; 372 return (nent); 373 } 374 375 /* 376 * Convert an Elf_Sym into an nlist structure. This fills in only the 377 * n_value and n_type members. 378 */ 379 static void 380 elf_sym_to_nlist(nl, s, shdr, shnum) 381 struct nlist *nl; 382 Elf_Sym *s; 383 Elf_Shdr *shdr; 384 int shnum; 385 { 386 nl->n_value = s->st_value; 387 388 switch (s->st_shndx) { 389 case SHN_UNDEF: 390 case SHN_COMMON: 391 nl->n_type = N_UNDF; 392 break; 393 case SHN_ABS: 394 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 395 N_FN : N_ABS; 396 break; 397 default: 398 if (s->st_shndx >= shnum) 399 nl->n_type = N_UNDF; 400 else { 401 Elf_Shdr *sh = shdr + s->st_shndx; 402 403 nl->n_type = sh->sh_type == SHT_PROGBITS ? 404 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 405 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 406 } 407 break; 408 } 409 410 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 411 ELF_ST_BIND(s->st_info) == STB_WEAK) 412 nl->n_type |= N_EXT; 413 } 414 #endif /* _NLIST_DO_ELF */ 415