external/bsd/libelf/dist/libelf_ehdr.c

   1 /*      $NetBSD: libelf_ehdr.c,v 1.4 2009/12/20 23:23:46 thorpej Exp $  */
   2
   3 /*-
   4  * Copyright (c) 2006 Joseph Koshy
   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  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $FreeBSD: src/lib/libelf/libelf_ehdr.c,v 1.2.10.1.2.1 2009/10/25 01:10:29 kensmith Exp $
  29  */
  30
  31 #include <sys/cdefs.h>
  32 /* __FBSDID("$FreeBSD: src/lib/libelf/libelf_ehdr.c,v 1.2.10.1.2.1 2009/10/25 01:10:29 kensmith Exp $"); */
  33
  34 #include <assert.h>
  35 #include <gelf.h>
  36 #include <libelf.h>
  37 #include <limits.h>
  38 #include <stdlib.h>
  39
  40 #include "_libelf.h"
  41
  42 /*
  43  * Retrieve counts for sections, phdrs and the section string table index
  44  * from section header #0 of the ELF object.
  45  */
  46 static int
  47 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
  48     uint16_t strndx)
  49 {
  50         Elf_Scn *scn;
  51         size_t fsz;
  52         void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
  53         uint32_t shtype;
  54
  55         assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
  56
  57         fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
  58         assert(fsz > 0);
  59
  60         if (e->e_rawsize < shoff + fsz) { /* raw file too small */
  61                 LIBELF_SET_ERROR(HEADER, 0);
  62                 return (0);
  63         }
  64
  65         if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL)
  66                 return (0);
  67
  68         if (shoff > SSIZE_MAX) {
  69                 LIBELF_SET_ERROR(HEADER, 0);
  70                 return (0);
  71         }
  72
  73         xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
  74         (*xlator)((void *) &scn->s_shdr, e->e_rawfile + (ssize_t)shoff,
  75             (size_t) 1, e->e_byteorder != _libelf_host_byteorder());
  76
  77 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
  78                 scn->s_shdr.s_shdr64.M)
  79
  80         if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) {
  81                 LIBELF_SET_ERROR(SECTION, 0);
  82                 return (0);
  83         }
  84
  85         if (GET_SHDR_MEMBER(sh_size) > UINT_MAX) {
  86                 LIBELF_SET_ERROR(HEADER, 0);
  87                 return (0);
  88         }
  89
  90         e->e_u.e_elf.e_nscn = (unsigned int)GET_SHDR_MEMBER(sh_size);
  91         e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum :
  92             GET_SHDR_MEMBER(sh_info);
  93         e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx :
  94             GET_SHDR_MEMBER(sh_link);
  95 #undef  GET_SHDR_MEMBER
  96
  97         return (1);
  98 }
  99
 100 #define EHDR_INIT(E,SZ)  do {                                           \
 101                 Elf##SZ##_Ehdr *eh = (E);                               \
 102                 eh->e_ident[EI_MAG0] = ELFMAG0;                         \
 103                 eh->e_ident[EI_MAG1] = ELFMAG1;                         \
 104                 eh->e_ident[EI_MAG2] = ELFMAG2;                         \
 105                 eh->e_ident[EI_MAG3] = ELFMAG3;                         \
 106                 eh->e_ident[EI_CLASS] = ELFCLASS##SZ;                   \
 107                 eh->e_ident[EI_DATA]  = ELFDATANONE;                    \
 108                 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version);      \
 109                 eh->e_machine = EM_NONE;                                \
 110                 eh->e_type    = ELF_K_NONE;                             \
 111                 eh->e_version = LIBELF_PRIVATE(version);                \
 112         } while (/*CONSTCOND*/0)
 113
 114 void *
 115 _libelf_ehdr(Elf *e, int ec, int allocate)
 116 {
 117         void *ehdr;
 118         size_t fsz, msz;
 119         uint16_t phnum, shnum, strndx;
 120         uint64_t shoff;
 121         void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
 122
 123         assert(ec == ELFCLASS32 || ec == ELFCLASS64);
 124
 125         if (e == NULL || e->e_kind != ELF_K_ELF) {
 126                 LIBELF_SET_ERROR(ARGUMENT, 0);
 127                 return (NULL);
 128         }
 129
 130         if (e->e_class != ELFCLASSNONE && e->e_class != ec) {
 131                 LIBELF_SET_ERROR(CLASS, 0);
 132                 return (NULL);
 133         }
 134
 135         if (e->e_version != EV_CURRENT) {
 136                 LIBELF_SET_ERROR(VERSION, 0);
 137                 return (NULL);
 138         }
 139
 140         if (e->e_class == ELFCLASSNONE)
 141                 e->e_class = ec;
 142
 143         if (ec == ELFCLASS32)
 144                 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32;
 145         else
 146                 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64;
 147
 148         if (ehdr != NULL)       /* already have a translated ehdr */
 149                 return (ehdr);
 150
 151         fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
 152         assert(fsz > 0);
 153
 154         if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) {
 155                 LIBELF_SET_ERROR(HEADER, 0);
 156                 return (NULL);
 157         }
 158
 159         msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT);
 160
 161         assert(msz > 0);
 162
 163         if ((ehdr = calloc((size_t) 1, msz)) == NULL) {
 164                 LIBELF_SET_ERROR(RESOURCE, 0);
 165                 return (NULL);
 166         }
 167
 168         if (ec == ELFCLASS32) {
 169                 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr;
 170                 EHDR_INIT(ehdr,32);
 171         } else {
 172                 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr;
 173                 EHDR_INIT(ehdr,64);
 174         }
 175
 176         if (allocate)
 177                 e->e_flags |= ELF_F_DIRTY;
 178
 179         if (e->e_cmd == ELF_C_WRITE)
 180                 return (ehdr);
 181
 182         xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec);
 183         (*xlator)(ehdr, e->e_rawfile, (size_t) 1,
 184             e->e_byteorder != _libelf_host_byteorder());
 185
 186         /*
 187          * If extended numbering is being used, read the correct
 188          * number of sections and program header entries.
 189          */
 190         if (ec == ELFCLASS32) {
 191                 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum;
 192                 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum;
 193                 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff;
 194                 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx;
 195         } else {
 196                 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum;
 197                 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum;
 198                 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff;
 199                 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx;
 200         }
 201
 202         if (shnum >= SHN_LORESERVE ||
 203             (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM ||
 204                 strndx == SHN_XINDEX))) {
 205                 LIBELF_SET_ERROR(HEADER, 0);
 206                 return (NULL);
 207         }
 208
 209         if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */
 210                 e->e_u.e_elf.e_nphdr = phnum;
 211                 e->e_u.e_elf.e_nscn = shnum;
 212                 e->e_u.e_elf.e_strndx = strndx;
 213         } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0)
 214                 return (NULL);
 215
 216         return (ehdr);
 217 }