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 #include <machine/elf.h> 51 #include <elf-hints.h> 52 53 int __fdnlist(int, struct nlist *); 54 int __elf_fdnlist(int, struct nlist *); 55 int __elf_is_okay__(Elf_Ehdr *); 56 57 int 58 nlist(const char *name, struct nlist *list) 59 { 60 int fd, n; 61 62 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 63 if (fd < 0) 64 return (-1); 65 n = __fdnlist(fd, list); 66 (void)_close(fd); 67 return (n); 68 } 69 70 static struct nlist_handlers { 71 int (*fn)(int fd, struct nlist *list); 72 } nlist_fn[] = { 73 { __elf_fdnlist }, 74 }; 75 76 int 77 __fdnlist(int fd, struct nlist *list) 78 { 79 int n = -1; 80 unsigned int i; 81 82 for (i = 0; i < nitems(nlist_fn); i++) { 83 n = (nlist_fn[i].fn)(fd, list); 84 if (n != -1) 85 break; 86 } 87 return (n); 88 } 89 90 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 91 92 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 93 94 /* 95 * __elf_is_okay__ - Determine if ehdr really 96 * is ELF and valid for the target platform. 97 * 98 * WARNING: This is NOT an ELF ABI function and 99 * as such its use should be restricted. 100 */ 101 int 102 __elf_is_okay__(Elf_Ehdr *ehdr) 103 { 104 int retval = 0; 105 /* 106 * We need to check magic, class size, endianess, 107 * and version before we look at the rest of the 108 * Elf_Ehdr structure. These few elements are 109 * represented in a machine independant fashion. 110 */ 111 if (IS_ELF(*ehdr) && 112 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 113 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 114 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 115 116 /* Now check the machine dependant header */ 117 if (ehdr->e_machine == ELF_TARG_MACH && 118 ehdr->e_version == ELF_TARG_VER) 119 retval = 1; 120 } 121 return retval; 122 } 123 124 int 125 __elf_fdnlist(int fd, struct nlist *list) 126 { 127 struct nlist *p; 128 Elf_Off symoff = 0, symstroff = 0; 129 Elf_Size symsize = 0, symstrsize = 0; 130 Elf_Ssize cc, i; 131 int nent = -1; 132 int errsave; 133 Elf_Sym sbuf[1024]; 134 Elf_Sym *s; 135 Elf_Ehdr ehdr; 136 char *strtab = NULL; 137 Elf_Shdr *shdr = NULL; 138 Elf_Size shdr_size; 139 void *base; 140 struct stat st; 141 142 /* Make sure obj is OK */ 143 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 144 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 145 !__elf_is_okay__(&ehdr) || 146 _fstat(fd, &st) < 0) 147 return (-1); 148 149 /* calculate section header table size */ 150 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 151 152 /* Make sure it's not too big to mmap */ 153 if (shdr_size > SIZE_T_MAX) { 154 errno = EFBIG; 155 return (-1); 156 } 157 158 /* mmap section header table */ 159 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 160 (off_t)ehdr.e_shoff); 161 if (base == MAP_FAILED) 162 return (-1); 163 shdr = (Elf_Shdr *)base; 164 165 /* 166 * Find the symbol table entry and it's corresponding 167 * string table entry. Version 1.1 of the ABI states 168 * that there is only one symbol table but that this 169 * could change in the future. 170 */ 171 for (i = 0; i < ehdr.e_shnum; i++) { 172 if (shdr[i].sh_type == SHT_SYMTAB) { 173 symoff = shdr[i].sh_offset; 174 symsize = shdr[i].sh_size; 175 symstroff = shdr[shdr[i].sh_link].sh_offset; 176 symstrsize = shdr[shdr[i].sh_link].sh_size; 177 break; 178 } 179 } 180 181 /* Check for files too large to mmap. */ 182 if (symstrsize > SIZE_T_MAX) { 183 errno = EFBIG; 184 goto done; 185 } 186 /* 187 * Map string table into our address space. This gives us 188 * an easy way to randomly access all the strings, without 189 * making the memory allocation permanent as with malloc/free 190 * (i.e., munmap will return it to the system). 191 */ 192 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 193 (off_t)symstroff); 194 if (base == MAP_FAILED) 195 goto done; 196 strtab = (char *)base; 197 198 /* 199 * clean out any left-over information for all valid entries. 200 * Type and value defined to be 0 if not found; historical 201 * versions cleared other and desc as well. Also figure out 202 * the largest string length so don't read any more of the 203 * string table than we have to. 204 * 205 * XXX clearing anything other than n_type and n_value violates 206 * the semantics given in the man page. 207 */ 208 nent = 0; 209 for (p = list; !ISLAST(p); ++p) { 210 p->n_type = 0; 211 p->n_other = 0; 212 p->n_desc = 0; 213 p->n_value = 0; 214 ++nent; 215 } 216 217 /* Don't process any further if object is stripped. */ 218 if (symoff == 0) 219 goto done; 220 221 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 222 nent = -1; 223 goto done; 224 } 225 226 while (symsize > 0 && nent > 0) { 227 cc = MIN(symsize, sizeof(sbuf)); 228 if (_read(fd, sbuf, cc) != cc) 229 break; 230 symsize -= cc; 231 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 232 char *name; 233 struct nlist *p; 234 235 name = strtab + s->st_name; 236 if (name[0] == '\0') 237 continue; 238 for (p = list; !ISLAST(p); p++) { 239 if ((p->n_un.n_name[0] == '_' && 240 strcmp(name, p->n_un.n_name+1) == 0) 241 || strcmp(name, p->n_un.n_name) == 0) { 242 elf_sym_to_nlist(p, s, shdr, 243 ehdr.e_shnum); 244 if (--nent <= 0) 245 break; 246 } 247 } 248 } 249 } 250 done: 251 errsave = errno; 252 if (strtab != NULL) 253 munmap(strtab, symstrsize); 254 if (shdr != NULL) 255 munmap(shdr, shdr_size); 256 errno = errsave; 257 return (nent); 258 } 259 260 /* 261 * Convert an Elf_Sym into an nlist structure. This fills in only the 262 * n_value and n_type members. 263 */ 264 static void 265 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 266 { 267 nl->n_value = s->st_value; 268 269 switch (s->st_shndx) { 270 case SHN_UNDEF: 271 case SHN_COMMON: 272 nl->n_type = N_UNDF; 273 break; 274 case SHN_ABS: 275 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 276 N_FN : N_ABS; 277 break; 278 default: 279 if (s->st_shndx >= shnum) 280 nl->n_type = N_UNDF; 281 else { 282 Elf_Shdr *sh = shdr + s->st_shndx; 283 284 nl->n_type = sh->sh_type == SHT_PROGBITS ? 285 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 286 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 287 } 288 break; 289 } 290 291 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 292 ELF_ST_BIND(s->st_info) == STB_WEAK) 293 nl->n_type |= N_EXT; 294 } 295