lib/libc/gen/nlist_elf32.c

   1 /* $NetBSD: nlist_elf32.c,v 1.38 2015/05/20 04:37:45 matt 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 1.38 2015/05/20 04:37:45 matt 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
  54 #include <assert.h>
  55 #include <errno.h>
  56 #include <stdio.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59 #include <nlist.h>
  60
  61 #include "nlist_private.h"
  62 #if defined(NLIST_ELF32) || defined(NLIST_ELF64)
  63 #include <sys/exec_elf.h>
  64 #endif
  65
  66 #include <sys/ksyms.h>          /* after sys/exec_elf.h */
  67
  68 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
  69     (defined(NLIST_ELF64) && (ELFSIZE == 64))
  70
  71 /* No need to check for off < 0 because it is unsigned */
  72 #define check(off, size)        (off + size > mappedsize)
  73 #define BAD                     goto out
  74 #define BADUNMAP                goto unmap
  75
  76 int
  77 ELFNAMEEND(__fdnlist)(int fd, struct nlist *list)
  78 {
  79         struct stat st;
  80         Elf_Ehdr ehdr;
  81 #if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
  82 #if (ELFSIZE == 32)
  83         Elf32_Half nshdr;
  84 #elif (ELFSIZE == 64)
  85         Elf64_Word nshdr;
  86 #endif
  87         /* Only support 64+32 mode on LP64 and those that have defined */
  88         /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
  89         Elf_Ehdr *ehdrp;
  90         Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
  91         Elf_Sym *symp;
  92         Elf_Off shdr_off;
  93         Elf_Word shdr_size;
  94         struct nlist *p;
  95         char *mappedfile, *strtab;
  96         size_t mappedsize, nsyms;
  97         int nent;
  98 #endif
  99         int rv;
 100         size_t i;
 101
 102         _DIAGASSERT(fd != -1);
 103         _DIAGASSERT(list != NULL);
 104
 105         rv = -1;
 106
 107         /*
 108          * If we can't fstat() the file, something bad is going on.
 109          */
 110         if (fstat(fd, &st) < 0)
 111                 BAD;
 112
 113         /*
 114          * Map the file in its entirety.
 115          */
 116         if ((uintmax_t)st.st_size > (uintmax_t)SIZE_T_MAX) {
 117                 errno = EFBIG;
 118                 BAD;
 119         }
 120
 121         /*
 122          * Read the elf header of the file.
 123          */
 124         if ((ssize_t)(i = pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0)) == -1)
 125                 BAD;
 126
 127         /*
 128          * Check that the elf header is correct.
 129          */
 130         if (i != sizeof(Elf_Ehdr))
 131                 BAD;
 132         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
 133             ehdr.e_ident[EI_CLASS] != ELFCLASS)
 134                 BAD;
 135
 136         switch (ehdr.e_machine) {
 137         ELFDEFNNAME(MACHDEP_ID_CASES)
 138
 139         default:
 140                 BAD;
 141         }
 142 #if defined(_LP64) || ELFSIZE == 32 || defined(ELF64_MACHDEP_ID)
 143         symshdrp = symstrshdrp = NULL;
 144
 145         /* Only support 64+32 mode on LP64 and those that have defined */
 146         /* ELF64_MACHDEP_ID, otherwise no support for 64 mode on ILP32 */
 147         if (S_ISCHR(st.st_mode)) {
 148                 const char *nlistname;
 149                 Elf_Sym sym;
 150
 151                 /*
 152                  * Character device; assume /dev/ksyms.
 153                  */
 154                 nent = 0;
 155                 for (p = list; !ISLAST(p); ++p) {
 156                         struct ksyms_gsymbol kg;
 157                         int error;
 158
 159                         p->n_other = 0;
 160                         p->n_desc = 0;
 161                         nlistname = N_NAME(p);
 162                         if (*nlistname == '_')
 163                                 nlistname++;
 164
 165                         memset(&kg, 0, sizeof(kg));
 166                         kg.kg_name = nlistname;
 167 #ifdef OKIOCGSYMBOL
 168                         struct ksyms_ogsymbol okg;
 169                         error = ioctl(fd, KIOCGSYMBOL, &kg);
 170                         if (error == 0) {
 171                                 sym = kg.kg_sym;
 172                         } else if (error && errno == ENOTTY) {
 173                                 memset(&okg, 0, sizeof(okg));
 174                                 okg.kg_name = nlistname;
 175                                 okg.kg_sym = &sym;
 176                                 error = ioctl(fd, OKIOCGSYMBOL, &okg);
 177                         }
 178 #else
 179                         kg.kg_sym = &sym;
 180                         error = ioctl(fd, KIOCGSYMBOL, &kg);
 181 #endif
 182                         if (error == 0
 183 #if !defined(_LP64) && ELFSIZE == 64
 184 #if __mips__
 185                             && (intptr_t)sym.st_value == (intmax_t)sym.st_value
 186 #else
 187                             && (uintptr_t)sym.st_value == sym.st_value
 188 #endif
 189 #endif
 190                             && 1) {
 191                                 p->n_value = (uintptr_t)sym.st_value;
 192                                 switch (ELF_ST_TYPE(sym.st_info)) {
 193                                 case STT_NOTYPE:
 194                                         p->n_type = N_UNDF;
 195                                         break;
 196                                 case STT_COMMON:
 197                                 case STT_OBJECT:
 198                                         p->n_type = N_DATA;
 199                                         break;
 200                                 case STT_FUNC:
 201                                         p->n_type = N_TEXT;
 202                                         break;
 203                                 case STT_FILE:
 204                                         p->n_type = N_FN;
 205                                         break;
 206                                 default:
 207                                         p->n_type = 0;
 208                                         /* catch other enumerations for gcc */
 209                                         break;
 210                                 }
 211                                 if (ELF_ST_BIND(sym.st_info) != STB_LOCAL)
 212                                         p->n_type |= N_EXT;
 213                         } else {
 214                                 nent++;
 215                                 p->n_value = 0;
 216                                 p->n_type = 0;
 217                         }
 218                 }
 219                 return nent;
 220         }
 221
 222         mappedsize = (size_t)st.st_size;
 223         mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
 224             fd, (off_t)0);
 225         if (mappedfile == (char *)-1)
 226                 BAD;
 227
 228         /*
 229          * Make sure we can access the executable's header
 230          * directly, and make sure the recognize the executable
 231          * as an ELF binary.
 232          */
 233         if (check(0, sizeof *ehdrp))
 234                 BADUNMAP;
 235         ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0];
 236
 237         /*
 238          * Find the symbol list and string table.
 239          */
 240         nshdr = ehdrp->e_shnum;
 241         shdr_off = ehdrp->e_shoff;
 242         shdr_size = ehdrp->e_shentsize * nshdr;
 243
 244         if (check(shdr_off, shdr_size) ||
 245             (sizeof *shdrp != ehdrp->e_shentsize))
 246                 BADUNMAP;
 247         shdrp = (void *)&mappedfile[(size_t)shdr_off];
 248
 249         for (i = 0; i < nshdr; i++) {
 250                 if (shdrp[i].sh_type == SHT_SYMTAB) {
 251                         symshdrp = &shdrp[i];
 252                         symstrshdrp = &shdrp[shdrp[i].sh_link];
 253                 }
 254         }
 255
 256         /* Make sure we're not stripped. */
 257         if (symshdrp == NULL || symshdrp->sh_offset == 0)
 258                 BADUNMAP;
 259
 260         /* Make sure the symbols and strings are safely mapped. */
 261         if (check(symshdrp->sh_offset, symshdrp->sh_size))
 262                 BADUNMAP;
 263         if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
 264                 BADUNMAP;
 265
 266         symp = (void *)&mappedfile[(size_t)symshdrp->sh_offset];
 267         nsyms = (size_t)(symshdrp->sh_size / sizeof(*symp));
 268         strtab = &mappedfile[(size_t)symstrshdrp->sh_offset];
 269
 270         /*
 271          * Clean out any left-over information for all valid entries.
 272          * Type and value are defined to be 0 if not found; historical
 273          * versions cleared other and desc as well.
 274          *
 275          * XXX Clearing anything other than n_type and n_value violates
 276          * the semantics given in the man page.
 277          */
 278         nent = 0;
 279         for (p = list; !ISLAST(p); ++p) {
 280                 p->n_type = 0;
 281                 p->n_other = 0;
 282                 p->n_desc = 0;
 283                 p->n_value = 0;
 284                 ++nent;
 285         }
 286
 287         for (i = 0; i < nsyms; i++) {
 288                 for (p = list; !ISLAST(p); ++p) {
 289                         const char *nlistname;
 290                         char *symtabname;
 291
 292                         /* This may be incorrect */
 293                         nlistname = N_NAME(p);
 294                         if (*nlistname == '_')
 295                                 nlistname++;
 296
 297                         symtabname = &strtab[symp[i].st_name];
 298
 299                         if (!strcmp(symtabname, nlistname)) {
 300                                 /*
 301                                  * Translate (roughly) from ELF to nlist
 302                                  */
 303                                 p->n_value = (uintptr_t)symp[i].st_value;
 304                                 switch (ELF_ST_TYPE(symp[i].st_info)) {
 305                                 case STT_NOTYPE:
 306                                         p->n_type = N_UNDF;
 307                                         break;
 308                                 case STT_OBJECT:
 309                                 case STT_COMMON:
 310                                         p->n_type = N_DATA;
 311                                         break;
 312                                 case STT_FUNC:
 313                                         p->n_type = N_TEXT;
 314                                         break;
 315                                 case STT_FILE:
 316                                         p->n_type = N_FN;
 317                                         break;
 318                                 default:
 319                                         /* catch other enumerations for gcc */
 320                                         break;
 321                                 }
 322                                 if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL)
 323                                         p->n_type |= N_EXT;
 324                                 p->n_desc = 0;                  /* XXX */
 325                                 p->n_other = 0;                 /* XXX */
 326
 327                                 if (--nent <= 0)
 328                                         goto done;
 329                                 break;  /* into next run of outer loop */
 330                         }
 331                 }
 332         }
 333
 334 done:
 335         rv = nent;
 336 unmap:
 337         munmap(mappedfile, mappedsize);
 338 #endif /* _LP64 || ELFSIZE == 32 || ELF64_MACHDEP_ID */
 339 out:
 340         return (rv);
 341 }
 342
 343 #endif