1 /* $NetBSD: libelf_ehdr.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2006,2008 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 29 #if HAVE_NBTOOL_CONFIG_H 30 # include "nbtool_config.h" 31 #endif 32 33 #include <sys/cdefs.h> 34 35 #include <assert.h> 36 #include <gelf.h> 37 #include <libelf.h> 38 #include <stdlib.h> 39 40 #include "_libelf.h" 41 42 __RCSID("$NetBSD: libelf_ehdr.c,v 1.2 2014/03/09 16:58:04 christos Exp $"); 43 ELFTC_VCSID("Id: libelf_ehdr.c 2225 2011-11-26 18:55:54Z jkoshy "); 44 45 /* 46 * Retrieve counts for sections, phdrs and the section string table index 47 * from section header #0 of the ELF object. 48 */ 49 static int 50 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum, 51 uint16_t strndx) 52 { 53 Elf_Scn *scn; 54 size_t fsz; 55 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); 56 uint32_t shtype; 57 58 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); 59 60 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); 61 assert(fsz > 0); 62 63 if (e->e_rawsize < shoff + fsz) { /* raw file too small */ 64 LIBELF_SET_ERROR(HEADER, 0); 65 return (0); 66 } 67 68 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) 69 return (0); 70 71 if (shoff > SSIZE_MAX) { 72 LIBELF_SET_ERROR(HEADER, 0); 73 return (0); 74 } 75 76 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 77 (*xlator)((void *) &scn->s_shdr, sizeof(scn->s_shdr), 78 e->e_rawfile + shoff, (size_t) 1, 79 e->e_byteorder != _libelf_host_byteorder()); 80 81 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ 82 scn->s_shdr.s_shdr64.M) 83 84 if (GET_SHDR_MEMBER(sh_size) > UINT_MAX) { 85 LIBELF_SET_ERROR(HEADER, 0); 86 return (0); 87 } 88 89 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { 90 LIBELF_SET_ERROR(SECTION, 0); 91 return (0); 92 } 93 94 e->e_u.e_elf.e_nscn = (unsigned int)GET_SHDR_MEMBER(sh_size); 95 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : 96 GET_SHDR_MEMBER(sh_info); 97 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : 98 GET_SHDR_MEMBER(sh_link); 99 #undef GET_SHDR_MEMBER 100 101 return (1); 102 } 103 104 #define EHDR_INIT(E,SZ) do { \ 105 Elf##SZ##_Ehdr *eh = (E); \ 106 eh->e_ident[EI_MAG0] = ELFMAG0; \ 107 eh->e_ident[EI_MAG1] = ELFMAG1; \ 108 eh->e_ident[EI_MAG2] = ELFMAG2; \ 109 eh->e_ident[EI_MAG3] = ELFMAG3; \ 110 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ 111 eh->e_ident[EI_DATA] = ELFDATANONE; \ 112 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version); \ 113 eh->e_machine = EM_NONE; \ 114 eh->e_type = ELF_K_NONE; \ 115 eh->e_version = LIBELF_PRIVATE(version); \ 116 } while (/*CONSTCOND*/0) 117 118 void * 119 _libelf_ehdr(Elf *e, int ec, int allocate) 120 { 121 void *ehdr; 122 size_t fsz, msz; 123 uint16_t phnum, shnum, strndx; 124 uint64_t shoff; 125 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); 126 127 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 128 129 if (e == NULL || e->e_kind != ELF_K_ELF) { 130 LIBELF_SET_ERROR(ARGUMENT, 0); 131 return (NULL); 132 } 133 134 if (e->e_class != ELFCLASSNONE && e->e_class != ec) { 135 LIBELF_SET_ERROR(CLASS, 0); 136 return (NULL); 137 } 138 139 if (e->e_version != EV_CURRENT) { 140 LIBELF_SET_ERROR(VERSION, 0); 141 return (NULL); 142 } 143 144 if (e->e_class == ELFCLASSNONE) 145 e->e_class = ec; 146 147 if (ec == ELFCLASS32) 148 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; 149 else 150 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; 151 152 if (ehdr != NULL) /* already have a translated ehdr */ 153 return (ehdr); 154 155 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 156 assert(fsz > 0); 157 158 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) { 159 LIBELF_SET_ERROR(HEADER, 0); 160 return (NULL); 161 } 162 163 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT); 164 165 assert(msz > 0); 166 167 if ((ehdr = calloc((size_t) 1, msz)) == NULL) { 168 LIBELF_SET_ERROR(RESOURCE, 0); 169 return (NULL); 170 } 171 172 if (ec == ELFCLASS32) { 173 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; 174 EHDR_INIT(ehdr,32); 175 } else { 176 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; 177 EHDR_INIT(ehdr,64); 178 } 179 180 if (allocate) 181 e->e_flags |= ELF_F_DIRTY; 182 183 if (e->e_cmd == ELF_C_WRITE) 184 return (ehdr); 185 186 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec); 187 (*xlator)(ehdr, msz, e->e_rawfile, (size_t) 1, 188 e->e_byteorder != _libelf_host_byteorder()); 189 190 /* 191 * If extended numbering is being used, read the correct 192 * number of sections and program header entries. 193 */ 194 if (ec == ELFCLASS32) { 195 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; 196 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; 197 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; 198 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; 199 } else { 200 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; 201 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; 202 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; 203 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; 204 } 205 206 if (shnum >= SHN_LORESERVE || 207 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || 208 strndx == SHN_XINDEX))) { 209 LIBELF_SET_ERROR(HEADER, 0); 210 return (NULL); 211 } 212 213 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */ 214 e->e_u.e_elf.e_nphdr = phnum; 215 e->e_u.e_elf.e_nscn = shnum; 216 e->e_u.e_elf.e_strndx = strndx; 217 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) 218 return (NULL); 219 220 return (ehdr); 221 } 222