1 /*- 2 * Copyright (c) 2006,2008 Joseph Koshy 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 29 #include <assert.h> 30 #include <gelf.h> 31 #include <libelf.h> 32 #include <stdlib.h> 33 34 #include "_libelf.h" 35 36 ELFTC_VCSID("$Id: libelf_ehdr.c 3009 2014-03-23 01:49:59Z jkoshy $"); 37 38 /* 39 * Retrieve counts for sections, phdrs and the section string table index 40 * from section header #0 of the ELF object. 41 */ 42 static int 43 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum, 44 uint16_t strndx) 45 { 46 Elf_Scn *scn; 47 size_t fsz; 48 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 49 size_t _c, int _swap); 50 uint32_t shtype; 51 52 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); 53 54 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); 55 assert(fsz > 0); 56 57 if (e->e_rawsize < shoff + fsz) { /* raw file too small */ 58 LIBELF_SET_ERROR(HEADER, 0); 59 return (0); 60 } 61 62 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) 63 return (0); 64 65 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 66 (*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr), 67 (unsigned char *) e->e_rawfile + shoff, (size_t) 1, 68 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 69 70 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ 71 scn->s_shdr.s_shdr64.M) 72 73 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { 74 LIBELF_SET_ERROR(SECTION, 0); 75 return (0); 76 } 77 78 e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size); 79 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : 80 GET_SHDR_MEMBER(sh_info); 81 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : 82 GET_SHDR_MEMBER(sh_link); 83 #undef GET_SHDR_MEMBER 84 85 return (1); 86 } 87 88 #define EHDR_INIT(E,SZ) do { \ 89 Elf##SZ##_Ehdr *eh = (E); \ 90 eh->e_ident[EI_MAG0] = ELFMAG0; \ 91 eh->e_ident[EI_MAG1] = ELFMAG1; \ 92 eh->e_ident[EI_MAG2] = ELFMAG2; \ 93 eh->e_ident[EI_MAG3] = ELFMAG3; \ 94 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ 95 eh->e_ident[EI_DATA] = ELFDATANONE; \ 96 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \ 97 eh->e_machine = EM_NONE; \ 98 eh->e_type = ELF_K_NONE; \ 99 eh->e_version = LIBELF_PRIVATE(version); \ 100 } while (0) 101 102 void * 103 _libelf_ehdr(Elf *e, int ec, int allocate) 104 { 105 void *ehdr; 106 size_t fsz, msz; 107 uint16_t phnum, shnum, strndx; 108 uint64_t shoff; 109 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 110 size_t _c, int _swap); 111 112 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 113 114 if (e == NULL || e->e_kind != ELF_K_ELF) { 115 LIBELF_SET_ERROR(ARGUMENT, 0); 116 return (NULL); 117 } 118 119 if (e->e_class != ELFCLASSNONE && e->e_class != ec) { 120 LIBELF_SET_ERROR(CLASS, 0); 121 return (NULL); 122 } 123 124 if (e->e_version != EV_CURRENT) { 125 LIBELF_SET_ERROR(VERSION, 0); 126 return (NULL); 127 } 128 129 if (e->e_class == ELFCLASSNONE) 130 e->e_class = ec; 131 132 if (ec == ELFCLASS32) 133 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; 134 else 135 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; 136 137 if (ehdr != NULL) /* already have a translated ehdr */ 138 return (ehdr); 139 140 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 141 assert(fsz > 0); 142 143 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) { 144 LIBELF_SET_ERROR(HEADER, 0); 145 return (NULL); 146 } 147 148 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT); 149 150 assert(msz > 0); 151 152 if ((ehdr = calloc((size_t) 1, msz)) == NULL) { 153 LIBELF_SET_ERROR(RESOURCE, 0); 154 return (NULL); 155 } 156 157 if (ec == ELFCLASS32) { 158 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; 159 EHDR_INIT(ehdr,32); 160 } else { 161 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; 162 EHDR_INIT(ehdr,64); 163 } 164 165 if (allocate) 166 e->e_flags |= ELF_F_DIRTY; 167 168 if (e->e_cmd == ELF_C_WRITE) 169 return (ehdr); 170 171 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec); 172 (*xlator)((unsigned char*) ehdr, msz, e->e_rawfile, (size_t) 1, 173 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 174 175 /* 176 * If extended numbering is being used, read the correct 177 * number of sections and program header entries. 178 */ 179 if (ec == ELFCLASS32) { 180 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; 181 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; 182 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; 183 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; 184 } else { 185 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; 186 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; 187 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; 188 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; 189 } 190 191 if (shnum >= SHN_LORESERVE || 192 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || 193 strndx == SHN_XINDEX))) { 194 LIBELF_SET_ERROR(HEADER, 0); 195 return (NULL); 196 } 197 198 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */ 199 e->e_u.e_elf.e_nphdr = phnum; 200 e->e_u.e_elf.e_nscn = shnum; 201 e->e_u.e_elf.e_strndx = strndx; 202 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) 203 return (NULL); 204 205 return (ehdr); 206 } 207