1/* $OpenBSD: i386_nlist.c,v 1.9 2022/12/28 21:30:16 jmc Exp $ */ 2/* 3 * Copyright (c) 1989, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31#define ELFSIZE 32 32 33#include <sys/types.h> 34#include <sys/mman.h> 35#include <sys/stat.h> 36 37#include <elf.h> 38#include <errno.h> 39#include <fcntl.h> 40#include <nlist.h> 41#include <stdint.h> 42#include <stdlib.h> 43#include <string.h> 44#include <unistd.h> 45 46#define MINIMUM(a, b) (((a) < (b)) ? (a) : (b)) 47 48static int __elf_fdnlist(int, struct nlist *); 49static int __elf_is_okay__(Elf_Ehdr *ehdr); 50 51int nlist_elf32(const char *, struct nlist *); 52 53#define ISLAST(p) (p->n_name == 0 || p->n_name[0] == 0) 54 55/* 56 * __elf_is_okay__ - Determine if ehdr really 57 * is ELF and valid for the target platform. 58 * 59 * WARNING: This is NOT a ELF ABI function and 60 * as such its use should be restricted. 61 */ 62static int 63__elf_is_okay__(Elf_Ehdr *ehdr) 64{ 65 int retval = 0; 66 /* 67 * We need to check magic, class size, endianness, 68 * and version before we look at the rest of the 69 * Elf_Ehdr structure. These few elements are 70 * represented in a machine independent fashion. 71 */ 72 73 /* 74 * We are constructing a 32-bit executable. So we can't 75 * use the libc nlist.c, which would be upset. Manually 76 * check for the i386 values for EI_CLASS and e_machine. 77 */ 78 79 if (IS_ELF(*ehdr) && 80 ehdr->e_ident[EI_CLASS] == ELFCLASS32 && 81 ehdr->e_ident[EI_DATA] == ELF_TARG_DATA && 82 ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) { 83 84 /* Now check the machine dependent header */ 85 if (ehdr->e_machine == EM_386 && 86 ehdr->e_version == ELF_TARG_VER) 87 retval = 1; 88 } 89 90 return retval; 91} 92 93static int 94__elf_fdnlist(int fd, struct nlist *list) 95{ 96 struct nlist *p; 97 caddr_t strtab; 98 Elf_Off symoff = 0, symstroff = 0; 99 Elf_Word symsize = 0, symstrsize = 0; 100 Elf_Sword nent, cc, i; 101 Elf_Sym sbuf[1024]; 102 Elf_Sym *s; 103 Elf_Ehdr ehdr; 104 Elf_Shdr *shdr = NULL; 105 Elf_Word shdr_size; 106 struct stat st; 107 int usemalloc = 0; 108 size_t left, len; 109 110 /* Make sure obj is OK */ 111 if (pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0) != sizeof(Elf_Ehdr) || 112 !__elf_is_okay__(&ehdr) || fstat(fd, &st) == -1) 113 return (-1); 114 115 /* calculate section header table size */ 116 shdr_size = ehdr.e_shentsize * ehdr.e_shnum; 117 118 /* Make sure it's not too big to mmap */ 119 if (SIZE_MAX - ehdr.e_shoff < shdr_size || 120 (S_ISREG(st.st_mode) && ehdr.e_shoff + shdr_size > st.st_size)) { 121 errno = EFBIG; 122 return (-1); 123 } 124 125 /* mmap section header table */ 126 shdr = (Elf_Shdr *)mmap(NULL, (size_t)shdr_size, PROT_READ, 127 MAP_SHARED|MAP_FILE, fd, (off_t) ehdr.e_shoff); 128 if (shdr == MAP_FAILED) { 129 usemalloc = 1; 130 if ((shdr = malloc(shdr_size)) == NULL) 131 return (-1); 132 133 if (pread(fd, shdr, shdr_size, (off_t)ehdr.e_shoff) != 134 shdr_size) { 135 free(shdr); 136 return (-1); 137 } 138 } 139 140 /* 141 * Find the symbol table entry and its corresponding 142 * string table entry. Version 1.1 of the ABI states 143 * that there is only one symbol table but that this 144 * could change in the future. 145 */ 146 for (i = 0; i < ehdr.e_shnum; i++) { 147 if (shdr[i].sh_type == SHT_SYMTAB) { 148 if (shdr[i].sh_link >= ehdr.e_shnum) 149 continue; 150 symoff = shdr[i].sh_offset; 151 symsize = shdr[i].sh_size; 152 symstroff = shdr[shdr[i].sh_link].sh_offset; 153 symstrsize = shdr[shdr[i].sh_link].sh_size; 154 break; 155 } 156 } 157 158 /* Flush the section header table */ 159 if (usemalloc) 160 free(shdr); 161 else 162 munmap((caddr_t)shdr, shdr_size); 163 164 /* 165 * clean out any left-over information for all valid entries. 166 * Type and value defined to be 0 if not found; historical 167 * versions cleared other and desc as well. Also figure out 168 * the largest string length so don't read any more of the 169 * string table than we have to. 170 * 171 * XXX clearing anything other than n_type and n_value violates 172 * the semantics given in the man page. 173 */ 174 nent = 0; 175 for (p = list; !ISLAST(p); ++p) { 176 p->n_type = 0; 177 p->n_other = 0; 178 p->n_desc = 0; 179 p->n_value = 0; 180 ++nent; 181 } 182 183 /* Don't process any further if object is stripped. */ 184 /* ELFism - dunno if stripped by looking at header */ 185 if (symoff == 0) 186 return nent; 187 188 /* Check for files too large to mmap. */ 189 if (SIZE_MAX - symstrsize < symstroff || 190 (S_ISREG(st.st_mode) && symstrsize + symstroff > st.st_size)) { 191 errno = EFBIG; 192 return (-1); 193 } 194 195 /* 196 * Map string table into our address space. This gives us 197 * an easy way to randomly access all the strings, without 198 * making the memory allocation permanent as with malloc/free 199 * (i.e., munmap will return it to the system). 200 */ 201 if (usemalloc) { 202 if ((strtab = malloc(symstrsize)) == NULL) 203 return (-1); 204 if (pread(fd, strtab, symstrsize, (off_t)symstroff) != 205 symstrsize) { 206 free(strtab); 207 return (-1); 208 } 209 } else { 210 strtab = mmap(NULL, (size_t)symstrsize, PROT_READ, 211 MAP_SHARED|MAP_FILE, fd, (off_t) symstroff); 212 if (strtab == MAP_FAILED) 213 return (-1); 214 } 215 216 while (symsize >= sizeof(Elf_Sym)) { 217 cc = MINIMUM(symsize, sizeof(sbuf)); 218 if (pread(fd, sbuf, cc, (off_t)symoff) != cc) 219 break; 220 symsize -= cc; 221 symoff += cc; 222 for (s = sbuf; cc > 0; ++s, cc -= sizeof(*s)) { 223 Elf_Word soff = s->st_name; 224 225 if (soff == 0 || soff >= symstrsize) 226 continue; 227 left = symstrsize - soff; 228 229 for (p = list; !ISLAST(p); p++) { 230 char *sym; 231 232 /* 233 * First we check for the symbol as it was 234 * provided by the user. If that fails 235 * and the first char is an '_', skip over 236 * the '_' and try again. 237 * XXX - What do we do when the user really 238 * wants '_foo' and there are symbols 239 * for both 'foo' and '_foo' in the 240 * table and 'foo' is first? 241 */ 242 sym = p->n_name; 243 len = strlen(sym); 244 245 if ((len >= left || 246 strcmp(&strtab[soff], sym) != 0) && 247 (sym[0] != '_' || len - 1 >= left || 248 strcmp(&strtab[soff], sym + 1) != 0)) 249 continue; 250 251 p->n_value = s->st_value; 252 253 /* XXX - type conversion */ 254 /* is pretty rude. */ 255 switch(ELF_ST_TYPE(s->st_info)) { 256 case STT_NOTYPE: 257 switch (s->st_shndx) { 258 case SHN_UNDEF: 259 p->n_type = N_UNDF; 260 break; 261 case SHN_ABS: 262 p->n_type = N_ABS; 263 break; 264 case SHN_COMMON: 265 p->n_type = N_COMM; 266 break; 267 default: 268 p->n_type = N_COMM | N_EXT; 269 break; 270 } 271 break; 272 case STT_OBJECT: 273 p->n_type = N_DATA; 274 break; 275 case STT_FUNC: 276 p->n_type = N_TEXT; 277 break; 278 case STT_FILE: 279 p->n_type = N_FN; 280 break; 281 } 282 if (ELF_ST_BIND(s->st_info) == STB_LOCAL) 283 p->n_type = N_EXT; 284 p->n_desc = 0; 285 p->n_other = 0; 286 if (--nent <= 0) 287 break; 288 } 289 } 290 } 291 if (usemalloc) 292 free(strtab); 293 else 294 munmap(strtab, symstrsize); 295 return (nent); 296} 297 298int 299nlist_elf32(const char *name, struct nlist *list) 300{ 301 int fd, n; 302 303 fd = open(name, O_RDONLY); 304 if (fd == -1) 305 return (-1); 306 n = __elf_fdnlist(fd, list); 307 close(fd); 308 309 return (n); 310} 311