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 "namespace.h" 33 #include <sys/param.h> 34 #include <sys/mman.h> 35 #include <sys/stat.h> 36 #include <sys/file.h> 37 #include <arpa/inet.h> 38 39 #include <errno.h> 40 #include <a.out.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include <unistd.h> 44 #include "un-namespace.h" 45 46 #include <machine/elf.h> 47 #include <elf-hints.h> 48 49 int __fdnlist(int, struct nlist *); 50 int __elf_fdnlist(int, struct nlist *); 51 int __elf_is_okay__(Elf_Ehdr *); 52 53 int 54 nlist(const char *name, struct nlist *list) 55 { 56 int fd, n; 57 58 fd = _open(name, O_RDONLY | O_CLOEXEC, 0); 59 if (fd < 0) 60 return (-1); 61 n = __fdnlist(fd, list); 62 (void)_close(fd); 63 return (n); 64 } 65 66 static struct nlist_handlers { 67 int (*fn)(int fd, struct nlist *list); 68 } nlist_fn[] = { 69 { __elf_fdnlist }, 70 }; 71 72 int 73 __fdnlist(int fd, struct nlist *list) 74 { 75 int n = -1; 76 unsigned int i; 77 78 for (i = 0; i < nitems(nlist_fn); i++) { 79 n = (nlist_fn[i].fn)(fd, list); 80 if (n != -1) 81 break; 82 } 83 return (n); 84 } 85 86 #define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0) 87 88 static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int); 89 90 /* 91 * __elf_is_okay__ - Determine if ehdr really 92 * is ELF and valid for the target platform. 93 * 94 * WARNING: This is NOT an ELF ABI function and 95 * as such its use should be restricted. 96 */ 97 int 98 __elf_is_okay__(Elf_Ehdr *ehdr) 99 { 100 int retval = 0; 101 /* 102 * We need to check magic, class size, endianess, 103 * and version before we look at the rest of the 104 * Elf_Ehdr structure. These few elements are 105 * represented in a machine independent fashion. 106 */ 107 if (IS_ELF(*ehdr) && 108 ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS && 109 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 110 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 111 112 /* Now check the machine dependant header */ 113 if (ehdr->e_machine == ELF_TARG_MACH && 114 ehdr->e_version == ELF_TARG_VER) 115 retval = 1; 116 } 117 return retval; 118 } 119 120 int 121 __elf_fdnlist(int fd, struct nlist *list) 122 { 123 struct nlist *p; 124 Elf_Off symoff = 0, symstroff = 0; 125 Elf_Size symsize = 0, symstrsize = 0; 126 Elf_Ssize cc, i; 127 int nent = -1; 128 int errsave; 129 Elf_Sym sbuf[1024]; 130 Elf_Sym *s; 131 Elf_Ehdr ehdr; 132 char *strtab = NULL; 133 Elf_Shdr *shdr = NULL; 134 Elf_Size shdr_size; 135 void *base; 136 struct stat st; 137 138 /* Make sure obj is OK */ 139 if (lseek(fd, (off_t)0, SEEK_SET) == -1 || 140 _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) || 141 !__elf_is_okay__(&ehdr) || 142 _fstat(fd, &st) < 0) 143 return (-1); 144 145 /* calculate section header table size */ 146 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 147 148 /* Make sure it's not too big to mmap */ 149 if (shdr_size > SIZE_T_MAX) { 150 errno = EFBIG; 151 return (-1); 152 } 153 154 /* mmap section header table */ 155 base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd, 156 (off_t)ehdr.e_shoff); 157 if (base == MAP_FAILED) 158 return (-1); 159 shdr = (Elf_Shdr *)base; 160 161 /* 162 * Find the symbol table entry and it's corresponding 163 * string table entry. Version 1.1 of the ABI states 164 * that there is only one symbol table but that this 165 * could change in the future. 166 */ 167 for (i = 0; i < ehdr.e_shnum; i++) { 168 if (shdr[i].sh_type == SHT_SYMTAB) { 169 symoff = shdr[i].sh_offset; 170 symsize = shdr[i].sh_size; 171 symstroff = shdr[shdr[i].sh_link].sh_offset; 172 symstrsize = shdr[shdr[i].sh_link].sh_size; 173 break; 174 } 175 } 176 177 /* Check for files too large to mmap. */ 178 if (symstrsize > SIZE_T_MAX) { 179 errno = EFBIG; 180 goto done; 181 } 182 /* 183 * Map string table into our address space. This gives us 184 * an easy way to randomly access all the strings, without 185 * making the memory allocation permanent as with malloc/free 186 * (i.e., munmap will return it to the system). 187 */ 188 base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd, 189 (off_t)symstroff); 190 if (base == MAP_FAILED) 191 goto done; 192 strtab = (char *)base; 193 194 /* 195 * clean out any left-over information for all valid entries. 196 * Type and value defined to be 0 if not found; historical 197 * versions cleared other and desc as well. Also figure out 198 * the largest string length so don't read any more of the 199 * string table than we have to. 200 * 201 * XXX clearing anything other than n_type and n_value violates 202 * the semantics given in the man page. 203 */ 204 nent = 0; 205 for (p = list; !ISLAST(p); ++p) { 206 p->n_type = 0; 207 p->n_other = 0; 208 p->n_desc = 0; 209 p->n_value = 0; 210 ++nent; 211 } 212 213 /* Don't process any further if object is stripped. */ 214 if (symoff == 0) 215 goto done; 216 217 if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) { 218 nent = -1; 219 goto done; 220 } 221 222 while (symsize > 0 && nent > 0) { 223 cc = MIN(symsize, sizeof(sbuf)); 224 if (_read(fd, sbuf, cc) != cc) 225 break; 226 symsize -= cc; 227 for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) { 228 char *name; 229 struct nlist *p; 230 231 name = strtab + s->st_name; 232 if (name[0] == '\0') 233 continue; 234 for (p = list; !ISLAST(p); p++) { 235 if ((p->n_un.n_name[0] == '_' && 236 strcmp(name, p->n_un.n_name+1) == 0) 237 || strcmp(name, p->n_un.n_name) == 0) { 238 elf_sym_to_nlist(p, s, shdr, 239 ehdr.e_shnum); 240 if (--nent <= 0) 241 break; 242 } 243 } 244 } 245 } 246 done: 247 errsave = errno; 248 if (strtab != NULL) 249 munmap(strtab, symstrsize); 250 if (shdr != NULL) 251 munmap(shdr, shdr_size); 252 errno = errsave; 253 return (nent); 254 } 255 256 /* 257 * Convert an Elf_Sym into an nlist structure. This fills in only the 258 * n_value and n_type members. 259 */ 260 static void 261 elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum) 262 { 263 nl->n_value = s->st_value; 264 265 switch (s->st_shndx) { 266 case SHN_UNDEF: 267 case SHN_COMMON: 268 nl->n_type = N_UNDF; 269 break; 270 case SHN_ABS: 271 nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ? 272 N_FN : N_ABS; 273 break; 274 default: 275 if (s->st_shndx >= shnum) 276 nl->n_type = N_UNDF; 277 else { 278 Elf_Shdr *sh = shdr + s->st_shndx; 279 280 nl->n_type = sh->sh_type == SHT_PROGBITS ? 281 (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) : 282 (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF); 283 } 284 break; 285 } 286 287 if (ELF_ST_BIND(s->st_info) == STB_GLOBAL || 288 ELF_ST_BIND(s->st_info) == STB_WEAK) 289 nl->n_type |= N_EXT; 290 } 291