1 /* $NetBSD: nlist_elf32.c,v 1.19 1999/11/04 02:00:17 erh Exp $ */ 2 3 /* 4 * Copyright (c) 1996 Christopher G. Demetriou. 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. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Christopher G. Demetriou 17 * for the NetBSD Project. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* If not included by nlist_elf64.c, ELFSIZE won't be defined. */ 34 #ifndef ELFSIZE 35 #define ELFSIZE 32 36 #endif 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 44 #include <assert.h> 45 #include <errno.h> 46 #include <stdio.h> 47 #include <string.h> 48 #include <unistd.h> 49 #include <a.out.h> /* for 'struct nlist' declaration */ 50 51 #include "nlist_private.h" 52 #if defined(NLIST_ELF32) || defined(NLIST_ELF64) 53 #include <sys/exec_elf.h> 54 #endif 55 56 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 57 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 58 59 /* No need to check for off < 0 because it is unsigned */ 60 #define check(off, size) (off + size > mappedsize) 61 #define BAD goto out 62 #define BADUNMAP goto unmap 63 64 int 65 ELFNAMEEND(__fdnlist)(fd, list) 66 int fd; 67 struct nlist *list; 68 { 69 struct stat st; 70 struct nlist *p; 71 char *mappedfile, *strtab; 72 size_t mappedsize; 73 Elf_Ehdr *ehdrp; 74 Elf_Shdr *shdrp, *symshdrp, *symstrshdrp; 75 Elf_Sym *symp; 76 Elf_Off shdr_off; 77 Elf_Word shdr_size; 78 #if (ELFSIZE == 32) 79 Elf32_Half nshdr; 80 #elif (ELFSIZE == 64) 81 Elf64_Half nshdr; 82 #endif 83 size_t i, nsyms; 84 int rv, nent; 85 86 _DIAGASSERT(fd != -1); 87 _DIAGASSERT(list != NULL); 88 89 rv = -1; 90 91 symshdrp = symstrshdrp = NULL; 92 93 /* 94 * If we can't fstat() the file, something bad is going on. 95 */ 96 if (fstat(fd, &st) < 0) 97 BAD; 98 99 /* 100 * Map the file in its entirety. 101 */ 102 if (st.st_size > SIZE_T_MAX) { 103 errno = EFBIG; 104 BAD; 105 } 106 mappedsize = (size_t)st.st_size; 107 mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE, 108 fd, (off_t)0); 109 if (mappedfile == (char *)-1) 110 BAD; 111 112 /* 113 * Make sure we can access the executable's header 114 * directly, and make sure the recognize the executable 115 * as an ELF binary. 116 */ 117 if (check(0, sizeof *ehdrp)) 118 BADUNMAP; 119 ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0]; 120 121 if (memcmp(ehdrp->e_ident, ELFMAG, SELFMAG) != 0 || 122 ehdrp->e_ident[EI_CLASS] != ELFCLASS) 123 BADUNMAP; 124 125 switch (ehdrp->e_machine) { 126 ELFDEFNNAME(MACHDEP_ID_CASES) 127 128 default: 129 BADUNMAP; 130 } 131 132 /* 133 * Find the symbol list and string table. 134 */ 135 nshdr = ehdrp->e_shnum; 136 shdr_off = ehdrp->e_shoff; 137 shdr_size = ehdrp->e_shentsize * nshdr; 138 139 if (check(shdr_off, shdr_size) || 140 (sizeof *shdrp != ehdrp->e_shentsize)) 141 BADUNMAP; 142 shdrp = (Elf_Shdr *)(void *)&mappedfile[shdr_off]; 143 144 for (i = 0; i < nshdr; i++) { 145 if (shdrp[i].sh_type == SHT_SYMTAB) { 146 symshdrp = &shdrp[i]; 147 symstrshdrp = &shdrp[shdrp[i].sh_link]; 148 } 149 } 150 151 /* Make sure we're not stripped. */ 152 if (symshdrp == NULL || symshdrp->sh_offset == 0) 153 BADUNMAP; 154 155 /* Make sure the symbols and strings are safely mapped. */ 156 if (check(symshdrp->sh_offset, symshdrp->sh_size)) 157 BADUNMAP; 158 if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size)) 159 BADUNMAP; 160 161 symp = (Elf_Sym *)(void *)&mappedfile[symshdrp->sh_offset]; 162 nsyms = symshdrp->sh_size / sizeof(*symp); 163 strtab = &mappedfile[symstrshdrp->sh_offset]; 164 165 /* 166 * Clean out any left-over information for all valid entries. 167 * Type and value are defined to be 0 if not found; historical 168 * versions cleared other and desc as well. 169 * 170 * XXX Clearing anything other than n_type and n_value violates 171 * the semantics given in the man page. 172 */ 173 nent = 0; 174 for (p = list; !ISLAST(p); ++p) { 175 p->n_type = 0; 176 p->n_other = 0; 177 p->n_desc = 0; 178 p->n_value = 0; 179 ++nent; 180 } 181 182 for (i = 0; i < nsyms; i++) { 183 for (p = list; !ISLAST(p); ++p) { 184 const char *nlistname; 185 char *symtabname; 186 187 /* This may be incorrect */ 188 nlistname = p->n_un.n_name; 189 if (*nlistname == '_') 190 nlistname++; 191 192 symtabname = &strtab[symp[i].st_name]; 193 194 if (!strcmp(symtabname, nlistname)) { 195 /* 196 * Translate (roughly) from ELF to nlist 197 */ 198 p->n_value = symp[i].st_value; 199 switch (ELFDEFNNAME(ST_TYPE)(symp[i].st_info)) { 200 case STT_NOTYPE: 201 p->n_type = N_UNDF; 202 break; 203 case STT_OBJECT: 204 p->n_type = N_DATA; 205 break; 206 case STT_FUNC: 207 p->n_type = N_TEXT; 208 break; 209 case STT_FILE: 210 p->n_type = N_FN; 211 break; 212 default: 213 /* catch other enumerations for gcc */ 214 break; 215 } 216 if (ELFDEFNNAME(ST_BIND)(symp[i].st_info) != 217 STB_LOCAL) 218 p->n_type |= N_EXT; 219 p->n_desc = 0; /* XXX */ 220 p->n_other = 0; /* XXX */ 221 222 if (--nent <= 0) 223 goto done; 224 break; /* into next run of outer loop */ 225 } 226 } 227 } 228 229 done: 230 rv = nent; 231 unmap: 232 munmap(mappedfile, mappedsize); 233 out: 234 return (rv); 235 } 236 237 #endif 238