1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __SCCSID("@(#)nlist.c 8.1 (Berkeley) 6/4/93"); 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 /* i386 is the only current FreeBSD architecture that used a.out format. */ 51 #ifdef __i386__ 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 int __elf_is_okay__(Elf_Ehdr *); 65 66 int 67 nlist(const char *name, struct nlist *list) 68 { 69 int fd, n; 70 71 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 72 if (fd < 0) 73 return (-1); 74 n = __fdnlist(fd, list); 75 (void)_close(fd); 76 return (n); 77 } 78 79 static struct nlist_handlers { 80 int (*fn)(int fd, struct nlist *list); 81 } nlist_fn[] = { 82 #ifdef _NLIST_DO_AOUT 83 { __aout_fdnlist }, 84 #endif 85 #ifdef _NLIST_DO_ELF 86 { __elf_fdnlist }, 87 #endif 88 }; 89 90 int 91 __fdnlist(int fd, struct nlist *list) 92 { 93 int n = -1; 94 unsigned int i; 95 96 for (i = 0; i < nitems(nlist_fn); i++) { 97 n = (nlist_fn[i].fn)(fd, list); 98 if (n != -1) 99 break; 100 } 101 return (n); 102 } 103 104 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 105 106 #ifdef _NLIST_DO_AOUT 107 int 108 __aout_fdnlist(int fd, struct nlist *list) 109 { 110 struct nlist *p, *symtab; 111 caddr_t strtab, a_out_mmap; 112 off_t stroff, symoff; 113 u_long symsize; 114 int nent; 115 struct exec * exec; 116 struct stat st; 117 118 /* check that file is at least as large as struct exec! */ 119 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 120 return (-1); 121 122 /* Check for files too large to mmap. */ 123 if (st.st_size > SIZE_T_MAX) { 124 errno = EFBIG; 125 return (-1); 126 } 127 128 /* 129 * Map the whole a.out file into our address space. 130 * We then find the string table withing this area. 131 * We do not just mmap the string table, as it probably 132 * does not start at a page boundary - we save ourselves a 133 * lot of nastiness by mmapping the whole file. 134 * 135 * This gives us an easy way to randomly access all the strings, 136 * without making the memory allocation permanent as with 137 * malloc/free (i.e., munmap will return it to the system). 138 */ 139 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 140 if (a_out_mmap == MAP_FAILED) 141 return (-1); 142 143 exec = (struct exec *)a_out_mmap; 144 if (N_BADMAG(*exec)) { 145 munmap(a_out_mmap, (size_t)st.st_size); 146 return (-1); 147 } 148 149 symoff = N_SYMOFF(*exec); 150 symsize = exec->a_syms; 151 stroff = symoff + symsize; 152 153 /* find the string table in our mmapped area */ 154 strtab = a_out_mmap + stroff; 155 symtab = (struct nlist *)(a_out_mmap + symoff); 156 157 /* 158 * clean out any left-over information for all valid entries. 159 * Type and value defined to be 0 if not found; historical 160 * versions cleared other and desc as well. Also figure out 161 * the largest string length so don't read any more of the 162 * string table than we have to. 163 * 164 * XXX clearing anything other than n_type and n_value violates 165 * the semantics given in the man page. 166 */ 167 nent = 0; 168 for (p = list; !ISLAST(p); ++p) { 169 p->n_type = 0; 170 p->n_other = 0; 171 p->n_desc = 0; 172 p->n_value = 0; 173 ++nent; 174 } 175 176 while (symsize > 0) { 177 int soff; 178 179 symsize-= sizeof(struct nlist); 180 soff = symtab->n_un.n_strx; 181 182 183 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 184 for (p = list; !ISLAST(p); p++) 185 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 186 p->n_value = symtab->n_value; 187 p->n_type = symtab->n_type; 188 p->n_desc = symtab->n_desc; 189 p->n_other = symtab->n_other; 190 if (--nent <= 0) 191 break; 192 } 193 symtab++; 194 } 195 munmap(a_out_mmap, (size_t)st.st_size); 196 return (nent); 197 } 198 #endif 199 200 #ifdef _NLIST_DO_ELF 201 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 202 203 /* 204 * __elf_is_okay__ - Determine if ehdr really 205 * is ELF and valid for the target platform. 206 * 207 * WARNING: This is NOT an ELF ABI function and 208 * as such its use should be restricted. 209 */ 210 int 211 __elf_is_okay__(Elf_Ehdr *ehdr) 212 { 213 int retval = 0; 214 /* 215 * We need to check magic, class size, endianess, 216 * and version before we look at the rest of the 217 * Elf_Ehdr structure. These few elements are 218 * represented in a machine independant fashion. 219 */ 220 if (IS_ELF(*ehdr) && 221 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 222 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 223 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 224 225 /* Now check the machine dependant header */ 226 if (ehdr->e_machine == ELF_TARG_MACH && 227 ehdr->e_version == ELF_TARG_VER) 228 retval = 1; 229 } 230 return retval; 231 } 232 233 int 234 __elf_fdnlist(int fd, struct nlist *list) 235 { 236 struct nlist *p; 237 Elf_Off symoff = 0, symstroff = 0; 238 Elf_Size symsize = 0, symstrsize = 0; 239 Elf_Ssize cc, i; 240 int nent = -1; 241 int errsave; 242 Elf_Sym sbuf[1024]; 243 Elf_Sym *s; 244 Elf_Ehdr ehdr; 245 char *strtab = NULL; 246 Elf_Shdr *shdr = NULL; 247 Elf_Size shdr_size; 248 void *base; 249 struct stat st; 250 251 /* Make sure obj is OK */ 252 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 253 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 254 !__elf_is_okay__(&ehdr) || 255 _fstat(fd, &st) < 0) 256 return (-1); 257 258 /* calculate section header table size */ 259 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 260 261 /* Make sure it's not too big to mmap */ 262 if (shdr_size > SIZE_T_MAX) { 263 errno = EFBIG; 264 return (-1); 265 } 266 267 /* mmap section header table */ 268 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 269 (off_t)ehdr.e_shoff); 270 if (base == MAP_FAILED) 271 return (-1); 272 shdr = (Elf_Shdr *)base; 273 274 /* 275 * Find the symbol table entry and it's corresponding 276 * string table entry. Version 1.1 of the ABI states 277 * that there is only one symbol table but that this 278 * could change in the future. 279 */ 280 for (i = 0; i < ehdr.e_shnum; i++) { 281 if (shdr[i].sh_type == SHT_SYMTAB) { 282 symoff = shdr[i].sh_offset; 283 symsize = shdr[i].sh_size; 284 symstroff = shdr[shdr[i].sh_link].sh_offset; 285 symstrsize = shdr[shdr[i].sh_link].sh_size; 286 break; 287 } 288 } 289 290 /* Check for files too large to mmap. */ 291 if (symstrsize > SIZE_T_MAX) { 292 errno = EFBIG; 293 goto done; 294 } 295 /* 296 * Map string table into our address space. This gives us 297 * an easy way to randomly access all the strings, without 298 * making the memory allocation permanent as with malloc/free 299 * (i.e., munmap will return it to the system). 300 */ 301 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 302 (off_t)symstroff); 303 if (base == MAP_FAILED) 304 goto done; 305 strtab = (char *)base; 306 307 /* 308 * clean out any left-over information for all valid entries. 309 * Type and value defined to be 0 if not found; historical 310 * versions cleared other and desc as well. Also figure out 311 * the largest string length so don't read any more of the 312 * string table than we have to. 313 * 314 * XXX clearing anything other than n_type and n_value violates 315 * the semantics given in the man page. 316 */ 317 nent = 0; 318 for (p = list; !ISLAST(p); ++p) { 319 p->n_type = 0; 320 p->n_other = 0; 321 p->n_desc = 0; 322 p->n_value = 0; 323 ++nent; 324 } 325 326 /* Don't process any further if object is stripped. */ 327 if (symoff == 0) 328 goto done; 329 330 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 331 nent = -1; 332 goto done; 333 } 334 335 while (symsize > 0 && nent > 0) { 336 cc = MIN(symsize, sizeof(sbuf)); 337 if (_read(fd, sbuf, cc) != cc) 338 break; 339 symsize -= cc; 340 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 341 char *name; 342 struct nlist *p; 343 344 name = strtab + s->st_name; 345 if (name[0] == '\0') 346 continue; 347 for (p = list; !ISLAST(p); p++) { 348 if ((p->n_un.n_name[0] == '_' && 349 strcmp(name, p->n_un.n_name+1) == 0) 350 || strcmp(name, p->n_un.n_name) == 0) { 351 elf_sym_to_nlist(p, s, shdr, 352 ehdr.e_shnum); 353 if (--nent <= 0) 354 break; 355 } 356 } 357 } 358 } 359 done: 360 errsave = errno; 361 if (strtab != NULL) 362 munmap(strtab, symstrsize); 363 if (shdr != NULL) 364 munmap(shdr, shdr_size); 365 errno = errsave; 366 return (nent); 367 } 368 369 /* 370 * Convert an Elf_Sym into an nlist structure. This fills in only the 371 * n_value and n_type members. 372 */ 373 static void 374 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 375 { 376 nl->n_value = s->st_value; 377 378 switch (s->st_shndx) { 379 case SHN_UNDEF: 380 case SHN_COMMON: 381 nl->n_type = N_UNDF; 382 break; 383 case SHN_ABS: 384 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 385 N_FN : N_ABS; 386 break; 387 default: 388 if (s->st_shndx >= shnum) 389 nl->n_type = N_UNDF; 390 else { 391 Elf_Shdr *sh = shdr + s->st_shndx; 392 393 nl->n_type = sh->sh_type == SHT_PROGBITS ? 394 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 395 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 396 } 397 break; 398 } 399 400 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 401 ELF_ST_BIND(s->st_info) == STB_WEAK) 402 nl->n_type |= N_EXT; 403 } 404 #endif /* _NLIST_DO_ELF */ 405