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 #if defined(LIBC_SCCS) && !defined(lint) 33 static char sccsid[] = "@(#)nlist.c 8.1 (Berkeley) 6/4/93"; 34 #endif /* LIBC_SCCS and not lint */ 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "namespace.h" 39 #include <sys/param.h> 40 #include <sys/mman.h> 41 #include <sys/stat.h> 42 #include <sys/file.h> 43 #include <arpa/inet.h> 44 45 #include <errno.h> 46 #include <a.out.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 #include "un-namespace.h" 51 52 /* i386 is the only current FreeBSD architecture that used a.out format. */ 53 #ifdef __i386__ 54 #define _NLIST_DO_AOUT 55 #endif 56 #define _NLIST_DO_ELF 57 58 #ifdef _NLIST_DO_ELF 59 #include <machine/elf.h> 60 #include <elf-hints.h> 61 #endif 62 63 int __fdnlist(int, struct nlist *); 64 int __aout_fdnlist(int, struct nlist *); 65 int __elf_fdnlist(int, struct nlist *); 66 int __elf_is_okay__(Elf_Ehdr *); 67 68 int 69 nlist(const char *name, struct nlist *list) 70 { 71 int fd, n; 72 73 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 74 if (fd < 0) 75 return (-1); 76 n = __fdnlist(fd, list); 77 (void)_close(fd); 78 return (n); 79 } 80 81 static struct nlist_handlers { 82 int (*fn)(int fd, struct nlist *list); 83 } nlist_fn[] = { 84 #ifdef _NLIST_DO_AOUT 85 { __aout_fdnlist }, 86 #endif 87 #ifdef _NLIST_DO_ELF 88 { __elf_fdnlist }, 89 #endif 90 }; 91 92 int 93 __fdnlist(int fd, struct nlist *list) 94 { 95 int n = -1; 96 unsigned int i; 97 98 for (i = 0; i < nitems(nlist_fn); 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(int fd, struct nlist *list) 111 { 112 struct nlist *p, *symtab; 113 caddr_t strtab, a_out_mmap; 114 off_t stroff, symoff; 115 u_long symsize; 116 int nent; 117 struct exec * exec; 118 struct stat st; 119 120 /* check that file is at least as large as struct exec! */ 121 if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec))) 122 return (-1); 123 124 /* Check for files too large to mmap. */ 125 if (st.st_size > SIZE_T_MAX) { 126 errno = EFBIG; 127 return (-1); 128 } 129 130 /* 131 * Map the whole a.out file into our address space. 132 * We then find the string table withing this area. 133 * We do not just mmap the string table, as it probably 134 * does not start at a page boundary - we save ourselves a 135 * lot of nastiness by mmapping the whole file. 136 * 137 * This gives us an easy way to randomly access all the strings, 138 * without making the memory allocation permanent as with 139 * malloc/free (i.e., munmap will return it to the system). 140 */ 141 a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0); 142 if (a_out_mmap == MAP_FAILED) 143 return (-1); 144 145 exec = (struct exec *)a_out_mmap; 146 if (N_BADMAG(*exec)) { 147 munmap(a_out_mmap, (size_t)st.st_size); 148 return (-1); 149 } 150 151 symoff = N_SYMOFF(*exec); 152 symsize = exec->a_syms; 153 stroff = symoff + symsize; 154 155 /* find the string table in our mmapped area */ 156 strtab = a_out_mmap + stroff; 157 symtab = (struct nlist *)(a_out_mmap + symoff); 158 159 /* 160 * clean out any left-over information for all valid entries. 161 * Type and value defined to be 0 if not found; historical 162 * versions cleared other and desc as well. Also figure out 163 * the largest string length so don't read any more of the 164 * string table than we have to. 165 * 166 * XXX clearing anything other than n_type and n_value violates 167 * the semantics given in the man page. 168 */ 169 nent = 0; 170 for (p = list; !ISLAST(p); ++p) { 171 p->n_type = 0; 172 p->n_other = 0; 173 p->n_desc = 0; 174 p->n_value = 0; 175 ++nent; 176 } 177 178 while (symsize > 0) { 179 int soff; 180 181 symsize-= sizeof(struct nlist); 182 soff = symtab->n_un.n_strx; 183 184 185 if (soff != 0 && (symtab->n_type & N_STAB) == 0) 186 for (p = list; !ISLAST(p); p++) 187 if (!strcmp(&strtab[soff], p->n_un.n_name)) { 188 p->n_value = symtab->n_value; 189 p->n_type = symtab->n_type; 190 p->n_desc = symtab->n_desc; 191 p->n_other = symtab->n_other; 192 if (--nent <= 0) 193 break; 194 } 195 symtab++; 196 } 197 munmap(a_out_mmap, (size_t)st.st_size); 198 return (nent); 199 } 200 #endif 201 202 #ifdef _NLIST_DO_ELF 203 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 204 205 /* 206 * __elf_is_okay__ - Determine if ehdr really 207 * is ELF and valid for the target platform. 208 * 209 * WARNING: This is NOT an ELF ABI function and 210 * as such its use should be restricted. 211 */ 212 int 213 __elf_is_okay__(Elf_Ehdr *ehdr) 214 { 215 int retval = 0; 216 /* 217 * We need to check magic, class size, endianess, 218 * and version before we look at the rest of the 219 * Elf_Ehdr structure. These few elements are 220 * represented in a machine independant fashion. 221 */ 222 if (IS_ELF(*ehdr) && 223 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 224 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 225 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 226 227 /* Now check the machine dependant header */ 228 if (ehdr->e_machine == ELF_TARG_MACH && 229 ehdr->e_version == ELF_TARG_VER) 230 retval = 1; 231 } 232 return retval; 233 } 234 235 int 236 __elf_fdnlist(int fd, struct nlist *list) 237 { 238 struct nlist *p; 239 Elf_Off symoff = 0, symstroff = 0; 240 Elf_Size symsize = 0, symstrsize = 0; 241 Elf_Ssize cc, i; 242 int nent = -1; 243 int errsave; 244 Elf_Sym sbuf[1024]; 245 Elf_Sym *s; 246 Elf_Ehdr ehdr; 247 char *strtab = NULL; 248 Elf_Shdr *shdr = NULL; 249 Elf_Size shdr_size; 250 void *base; 251 struct stat st; 252 253 /* Make sure obj is OK */ 254 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 255 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 256 !__elf_is_okay__(&ehdr) || 257 _fstat(fd, &st) < 0) 258 return (-1); 259 260 /* calculate section header table size */ 261 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 262 263 /* Make sure it's not too big to mmap */ 264 if (shdr_size > SIZE_T_MAX) { 265 errno = EFBIG; 266 return (-1); 267 } 268 269 /* mmap section header table */ 270 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 271 (off_t)ehdr.e_shoff); 272 if (base == MAP_FAILED) 273 return (-1); 274 shdr = (Elf_Shdr *)base; 275 276 /* 277 * Find the symbol table entry and it's corresponding 278 * string table entry. Version 1.1 of the ABI states 279 * that there is only one symbol table but that this 280 * could change in the future. 281 */ 282 for (i = 0; i < ehdr.e_shnum; i++) { 283 if (shdr[i].sh_type == SHT_SYMTAB) { 284 symoff = shdr[i].sh_offset; 285 symsize = shdr[i].sh_size; 286 symstroff = shdr[shdr[i].sh_link].sh_offset; 287 symstrsize = shdr[shdr[i].sh_link].sh_size; 288 break; 289 } 290 } 291 292 /* Check for files too large to mmap. */ 293 if (symstrsize > SIZE_T_MAX) { 294 errno = EFBIG; 295 goto done; 296 } 297 /* 298 * Map string table into our address space. This gives us 299 * an easy way to randomly access all the strings, without 300 * making the memory allocation permanent as with malloc/free 301 * (i.e., munmap will return it to the system). 302 */ 303 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 304 (off_t)symstroff); 305 if (base == MAP_FAILED) 306 goto done; 307 strtab = (char *)base; 308 309 /* 310 * clean out any left-over information for all valid entries. 311 * Type and value defined to be 0 if not found; historical 312 * versions cleared other and desc as well. Also figure out 313 * the largest string length so don't read any more of the 314 * string table than we have to. 315 * 316 * XXX clearing anything other than n_type and n_value violates 317 * the semantics given in the man page. 318 */ 319 nent = 0; 320 for (p = list; !ISLAST(p); ++p) { 321 p->n_type = 0; 322 p->n_other = 0; 323 p->n_desc = 0; 324 p->n_value = 0; 325 ++nent; 326 } 327 328 /* Don't process any further if object is stripped. */ 329 if (symoff == 0) 330 goto done; 331 332 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 333 nent = -1; 334 goto done; 335 } 336 337 while (symsize > 0 && nent > 0) { 338 cc = MIN(symsize, sizeof(sbuf)); 339 if (_read(fd, sbuf, cc) != cc) 340 break; 341 symsize -= cc; 342 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 343 char *name; 344 struct nlist *p; 345 346 name = strtab + s->st_name; 347 if (name[0] == '\0') 348 continue; 349 for (p = list; !ISLAST(p); p++) { 350 if ((p->n_un.n_name[0] == '_' && 351 strcmp(name, p->n_un.n_name+1) == 0) 352 || strcmp(name, p->n_un.n_name) == 0) { 353 elf_sym_to_nlist(p, s, shdr, 354 ehdr.e_shnum); 355 if (--nent <= 0) 356 break; 357 } 358 } 359 } 360 } 361 done: 362 errsave = errno; 363 if (strtab != NULL) 364 munmap(strtab, symstrsize); 365 if (shdr != NULL) 366 munmap(shdr, shdr_size); 367 errno = errsave; 368 return (nent); 369 } 370 371 /* 372 * Convert an Elf_Sym into an nlist structure. This fills in only the 373 * n_value and n_type members. 374 */ 375 static void 376 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 377 { 378 nl->n_value = s->st_value; 379 380 switch (s->st_shndx) { 381 case SHN_UNDEF: 382 case SHN_COMMON: 383 nl->n_type = N_UNDF; 384 break; 385 case SHN_ABS: 386 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 387 N_FN : N_ABS; 388 break; 389 default: 390 if (s->st_shndx >= shnum) 391 nl->n_type = N_UNDF; 392 else { 393 Elf_Shdr *sh = shdr + s->st_shndx; 394 395 nl->n_type = sh->sh_type == SHT_PROGBITS ? 396 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 397 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 398 } 399 break; 400 } 401 402 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 403 ELF_ST_BIND(s->st_info) == STB_WEAK) 404 nl->n_type |= N_EXT; 405 } 406 #endif /* _NLIST_DO_ELF */ 407