1 /* $NetBSD: nlist_elf32.c,v 1.33 2011/10/15 21:06:58 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1996 Christopher G. Demetriou 5 * 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed for the 18 * NetBSD Project. See http://www.NetBSD.org/ for 19 * information about NetBSD. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 * 34 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>> 35 */ 36 37 #include <sys/cdefs.h> 38 #if defined(LIBC_SCCS) && !defined(lint) 39 __RCSID("$NetBSD: nlist_elf32.c,v 1.33 2011/10/15 21:06:58 christos Exp $"); 40 #endif /* LIBC_SCCS and not lint */ 41 42 /* If not included by nlist_elf64.c, ELFSIZE won't be defined. */ 43 #ifndef ELFSIZE 44 #define ELFSIZE 32 45 #endif 46 47 #include "namespace.h" 48 #include <sys/param.h> 49 #include <sys/mman.h> 50 #include <sys/stat.h> 51 #include <sys/file.h> 52 #include <sys/ioctl.h> 53 #include <sys/ksyms.h> 54 55 #include <assert.h> 56 #include <errno.h> 57 #include <stdio.h> 58 #include <string.h> 59 #include <unistd.h> 60 #include <nlist.h> 61 62 #include "nlist_private.h" 63 #if defined(NLIST_ELF32) || defined(NLIST_ELF64) 64 #include <sys/exec_elf.h> 65 #endif 66 67 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \ 68 (defined(NLIST_ELF64) && (ELFSIZE == 64)) 69 70 /* No need to check for off < 0 because it is unsigned */ 71 #define check(off, size) (off + size > mappedsize) 72 #define BAD goto out 73 #define BADUNMAP goto unmap 74 75 int 76 ELFNAMEEND(__fdnlist)(fd, list) 77 int fd; 78 struct nlist *list; 79 { 80 struct stat st; 81 struct nlist *p; 82 char *mappedfile, *strtab; 83 size_t mappedsize; 84 Elf_Ehdr *ehdrp, ehdr; 85 Elf_Shdr *shdrp, *symshdrp, *symstrshdrp; 86 Elf_Sym *symp; 87 Elf_Off shdr_off; 88 Elf_Word shdr_size; 89 #if (ELFSIZE == 32) 90 Elf32_Half nshdr; 91 #elif (ELFSIZE == 64) 92 Elf64_Word nshdr; 93 #endif 94 size_t i, nsyms; 95 int rv, nent; 96 97 _DIAGASSERT(fd != -1); 98 _DIAGASSERT(list != NULL); 99 100 rv = -1; 101 102 symshdrp = symstrshdrp = NULL; 103 104 /* 105 * If we can't fstat() the file, something bad is going on. 106 */ 107 if (fstat(fd, &st) < 0) 108 BAD; 109 110 /* 111 * Map the file in its entirety. 112 */ 113 if ((uintmax_t)st.st_size > (uintmax_t)SIZE_T_MAX) { 114 errno = EFBIG; 115 BAD; 116 } 117 118 /* 119 * Read the elf header of the file. 120 */ 121 if ((ssize_t)(i = pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0)) == -1) 122 BAD; 123 124 /* 125 * Check that the elf header is correct. 126 */ 127 if (i != sizeof(Elf_Ehdr)) 128 BAD; 129 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || 130 ehdr.e_ident[EI_CLASS] != ELFCLASS) 131 BAD; 132 133 switch (ehdr.e_machine) { 134 ELFDEFNNAME(MACHDEP_ID_CASES) 135 136 default: 137 BAD; 138 } 139 140 if (S_ISCHR(st.st_mode)) { 141 const char *nlistname; 142 struct ksyms_gsymbol kg; 143 Elf_Sym sym; 144 145 /* 146 * Character device; assume /dev/ksyms. 147 */ 148 nent = 0; 149 for (p = list; !ISLAST(p); ++p) { 150 151 p->n_other = 0; 152 p->n_desc = 0; 153 nlistname = N_NAME(p); 154 if (*nlistname == '_') 155 nlistname++; 156 157 kg.kg_name = nlistname; 158 kg.kg_sym = &sym; 159 if (ioctl(fd, KIOCGSYMBOL, &kg) == 0) { 160 p->n_value = sym.st_value; 161 switch (ELF_ST_TYPE(sym.st_info)) { 162 case STT_NOTYPE: 163 p->n_type = N_UNDF; 164 break; 165 case STT_COMMON: 166 case STT_OBJECT: 167 p->n_type = N_DATA; 168 break; 169 case STT_FUNC: 170 p->n_type = N_TEXT; 171 break; 172 case STT_FILE: 173 p->n_type = N_FN; 174 break; 175 default: 176 p->n_type = 0; 177 /* catch other enumerations for gcc */ 178 break; 179 } 180 if (ELF_ST_BIND(sym.st_info) != STB_LOCAL) 181 p->n_type |= N_EXT; 182 } else { 183 nent++; 184 p->n_value = 0; 185 p->n_type = 0; 186 } 187 } 188 return nent; 189 } 190 191 mappedsize = (size_t)st.st_size; 192 mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE, 193 fd, (off_t)0); 194 if (mappedfile == (char *)-1) 195 BAD; 196 197 /* 198 * Make sure we can access the executable's header 199 * directly, and make sure the recognize the executable 200 * as an ELF binary. 201 */ 202 if (check(0, sizeof *ehdrp)) 203 BADUNMAP; 204 ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0]; 205 206 /* 207 * Find the symbol list and string table. 208 */ 209 nshdr = ehdrp->e_shnum; 210 shdr_off = ehdrp->e_shoff; 211 shdr_size = ehdrp->e_shentsize * nshdr; 212 213 if (check(shdr_off, shdr_size) || 214 (sizeof *shdrp != ehdrp->e_shentsize)) 215 BADUNMAP; 216 shdrp = (Elf_Shdr *)(void *)&mappedfile[shdr_off]; 217 218 for (i = 0; i < nshdr; i++) { 219 if (shdrp[i].sh_type == SHT_SYMTAB) { 220 symshdrp = &shdrp[i]; 221 symstrshdrp = &shdrp[shdrp[i].sh_link]; 222 } 223 } 224 225 /* Make sure we're not stripped. */ 226 if (symshdrp == NULL || symshdrp->sh_offset == 0) 227 BADUNMAP; 228 229 /* Make sure the symbols and strings are safely mapped. */ 230 if (check(symshdrp->sh_offset, symshdrp->sh_size)) 231 BADUNMAP; 232 if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size)) 233 BADUNMAP; 234 235 symp = (Elf_Sym *)(void *)&mappedfile[symshdrp->sh_offset]; 236 nsyms = symshdrp->sh_size / sizeof(*symp); 237 strtab = &mappedfile[symstrshdrp->sh_offset]; 238 239 /* 240 * Clean out any left-over information for all valid entries. 241 * Type and value are defined to be 0 if not found; historical 242 * versions cleared other and desc as well. 243 * 244 * XXX Clearing anything other than n_type and n_value violates 245 * the semantics given in the man page. 246 */ 247 nent = 0; 248 for (p = list; !ISLAST(p); ++p) { 249 p->n_type = 0; 250 p->n_other = 0; 251 p->n_desc = 0; 252 p->n_value = 0; 253 ++nent; 254 } 255 256 for (i = 0; i < nsyms; i++) { 257 for (p = list; !ISLAST(p); ++p) { 258 const char *nlistname; 259 char *symtabname; 260 261 /* This may be incorrect */ 262 nlistname = N_NAME(p); 263 if (*nlistname == '_') 264 nlistname++; 265 266 symtabname = &strtab[symp[i].st_name]; 267 268 if (!strcmp(symtabname, nlistname)) { 269 /* 270 * Translate (roughly) from ELF to nlist 271 */ 272 p->n_value = symp[i].st_value; 273 switch (ELF_ST_TYPE(symp[i].st_info)) { 274 case STT_NOTYPE: 275 p->n_type = N_UNDF; 276 break; 277 case STT_OBJECT: 278 case STT_COMMON: 279 p->n_type = N_DATA; 280 break; 281 case STT_FUNC: 282 p->n_type = N_TEXT; 283 break; 284 case STT_FILE: 285 p->n_type = N_FN; 286 break; 287 default: 288 /* catch other enumerations for gcc */ 289 break; 290 } 291 if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL) 292 p->n_type |= N_EXT; 293 p->n_desc = 0; /* XXX */ 294 p->n_other = 0; /* XXX */ 295 296 if (--nent <= 0) 297 goto done; 298 break; /* into next run of outer loop */ 299 } 300 } 301 } 302 303 done: 304 rv = nent; 305 unmap: 306 munmap(mappedfile, mappedsize); 307 out: 308 return (rv); 309 } 310 311 #endif 312