lib/libc/gen/nlist_elf32.c

   1 /* $NetBSD: nlist_elf32.c,v 1.30 2009/02/16 10:40:45 lukem 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 1.30 2009/02/16 10:40:45 lukem 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_Half 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_OBJECT:
 166                                         p->n_type = N_DATA;
 167                                         break;
 168                                 case STT_FUNC:
 169                                         p->n_type = N_TEXT;
 170                                         break;
 171                                 case STT_FILE:
 172                                         p->n_type = N_FN;
 173                                         break;
 174                                 default:
 175                                         p->n_type = 0;
 176                                         /* catch other enumerations for gcc */
 177                                         break;
 178                                 }
 179                                 if (ELF_ST_BIND(sym.st_info) != STB_LOCAL)
 180                                         p->n_type |= N_EXT;
 181                         } else {
 182                                 nent++;
 183                                 p->n_value = 0;
 184                                 p->n_type = 0;
 185                         }
 186                 }
 187                 return nent;
 188         }
 189
 190         mappedsize = (size_t)st.st_size;
 191         mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
 192             fd, (off_t)0);
 193         if (mappedfile == (char *)-1)
 194                 BAD;
 195
 196         /*
 197          * Make sure we can access the executable's header
 198          * directly, and make sure the recognize the executable
 199          * as an ELF binary.
 200          */
 201         if (check(0, sizeof *ehdrp))
 202                 BADUNMAP;
 203         ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0];
 204
 205         /*
 206          * Find the symbol list and string table.
 207          */
 208         nshdr = ehdrp->e_shnum;
 209         shdr_off = ehdrp->e_shoff;
 210         shdr_size = ehdrp->e_shentsize * nshdr;
 211
 212         if (check(shdr_off, shdr_size) ||
 213             (sizeof *shdrp != ehdrp->e_shentsize))
 214                 BADUNMAP;
 215         shdrp = (Elf_Shdr *)(void *)&mappedfile[shdr_off];
 216
 217         for (i = 0; i < nshdr; i++) {
 218                 if (shdrp[i].sh_type == SHT_SYMTAB) {
 219                         symshdrp = &shdrp[i];
 220                         symstrshdrp = &shdrp[shdrp[i].sh_link];
 221                 }
 222         }
 223
 224         /* Make sure we're not stripped. */
 225         if (symshdrp == NULL || symshdrp->sh_offset == 0)
 226                 BADUNMAP;
 227
 228         /* Make sure the symbols and strings are safely mapped. */
 229         if (check(symshdrp->sh_offset, symshdrp->sh_size))
 230                 BADUNMAP;
 231         if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
 232                 BADUNMAP;
 233
 234         symp = (Elf_Sym *)(void *)&mappedfile[symshdrp->sh_offset];
 235         nsyms = symshdrp->sh_size / sizeof(*symp);
 236         strtab = &mappedfile[symstrshdrp->sh_offset];
 237
 238         /*
 239          * Clean out any left-over information for all valid entries.
 240          * Type and value are defined to be 0 if not found; historical
 241          * versions cleared other and desc as well.
 242          *
 243          * XXX Clearing anything other than n_type and n_value violates
 244          * the semantics given in the man page.
 245          */
 246         nent = 0;
 247         for (p = list; !ISLAST(p); ++p) {
 248                 p->n_type = 0;
 249                 p->n_other = 0;
 250                 p->n_desc = 0;
 251                 p->n_value = 0;
 252                 ++nent;
 253         }
 254
 255         for (i = 0; i < nsyms; i++) {
 256                 for (p = list; !ISLAST(p); ++p) {
 257                         const char *nlistname;
 258                         char *symtabname;
 259
 260                         /* This may be incorrect */
 261                         nlistname = N_NAME(p);
 262                         if (*nlistname == '_')
 263                                 nlistname++;
 264
 265                         symtabname = &strtab[symp[i].st_name];
 266
 267                         if (!strcmp(symtabname, nlistname)) {
 268                                 /*
 269                                  * Translate (roughly) from ELF to nlist
 270                                  */
 271                                 p->n_value = symp[i].st_value;
 272                                 switch (ELF_ST_TYPE(symp[i].st_info)) {
 273                                 case STT_NOTYPE:
 274                                         p->n_type = N_UNDF;
 275                                         break;
 276                                 case STT_OBJECT:
 277                                         p->n_type = N_DATA;
 278                                         break;
 279                                 case STT_FUNC:
 280                                         p->n_type = N_TEXT;
 281                                         break;
 282                                 case STT_FILE:
 283                                         p->n_type = N_FN;
 284                                         break;
 285                                 default:
 286                                         /* catch other enumerations for gcc */
 287                                         break;
 288                                 }
 289                                 if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL)
 290                                         p->n_type |= N_EXT;
 291                                 p->n_desc = 0;                  /* XXX */
 292                                 p->n_other = 0;                 /* XXX */
 293
 294                                 if (--nent <= 0)
 295                                         goto done;
 296                                 break;  /* into next run of outer loop */
 297                         }
 298                 }
 299         }
 300
 301 done:
 302         rv = nent;
 303 unmap:
 304         munmap(mappedfile, mappedsize);
 305 out:
 306         return (rv);
 307 }
 308
 309 #endif