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 <assert.h> 28 #include <gelf.h> 29 #include <libelf.h> 30 #include <stdlib.h> 31 32 #include "_libelf.h" 33 34 ELFTC_VCSID("$Id: libelf_ehdr.c 3575 2017-09-14 02:13:36Z emaste $"); 35 36 /* 37 * Retrieve counts for sections, phdrs and the section string table index 38 * from section header #0 of the ELF object. 39 */ 40 static int 41 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum, 42 uint16_t strndx) 43 { 44 Elf_Scn *scn; 45 size_t fsz; 46 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 47 size_t _c, int _swap); 48 uint32_t shtype; 49 50 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); 51 52 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); 53 assert(fsz > 0); 54 55 if (e->e_rawsize < shoff + fsz) { /* raw file too small */ 56 LIBELF_SET_ERROR(HEADER, 0); 57 return (0); 58 } 59 60 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) 61 return (0); 62 63 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 64 (*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr), 65 (unsigned char *) e->e_rawfile + shoff, (size_t) 1, 66 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 67 68 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ 69 scn->s_shdr.s_shdr64.M) 70 71 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { 72 LIBELF_SET_ERROR(SECTION, 0); 73 return (0); 74 } 75 76 e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size); 77 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : 78 GET_SHDR_MEMBER(sh_info); 79 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : 80 GET_SHDR_MEMBER(sh_link); 81 #undef GET_SHDR_MEMBER 82 83 return (1); 84 } 85 86 #define EHDR_INIT(E,SZ) do { \ 87 Elf##SZ##_Ehdr *eh = (E); \ 88 eh->e_ident[EI_MAG0] = ELFMAG0; \ 89 eh->e_ident[EI_MAG1] = ELFMAG1; \ 90 eh->e_ident[EI_MAG2] = ELFMAG2; \ 91 eh->e_ident[EI_MAG3] = ELFMAG3; \ 92 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ 93 eh->e_ident[EI_DATA] = ELFDATANONE; \ 94 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \ 95 eh->e_machine = EM_NONE; \ 96 eh->e_type = ELF_K_NONE; \ 97 eh->e_version = LIBELF_PRIVATE(version); \ 98 } while (0) 99 100 void * 101 _libelf_ehdr(Elf *e, int ec, int allocate) 102 { 103 void *ehdr; 104 size_t fsz, msz; 105 uint16_t phnum, shnum, strndx; 106 uint64_t shoff; 107 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 108 size_t _c, int _swap); 109 110 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 111 112 if (e == NULL || e->e_kind != ELF_K_ELF) { 113 LIBELF_SET_ERROR(ARGUMENT, 0); 114 return (NULL); 115 } 116 117 if (e->e_class != ELFCLASSNONE && e->e_class != ec) { 118 LIBELF_SET_ERROR(CLASS, 0); 119 return (NULL); 120 } 121 122 if (e->e_version != EV_CURRENT) { 123 LIBELF_SET_ERROR(VERSION, 0); 124 return (NULL); 125 } 126 127 if (e->e_class == ELFCLASSNONE) 128 e->e_class = ec; 129 130 if (ec == ELFCLASS32) 131 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; 132 else 133 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; 134 135 if (ehdr != NULL) /* already have a translated ehdr */ 136 return (ehdr); 137 138 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 139 assert(fsz > 0); 140 141 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) { 142 LIBELF_SET_ERROR(HEADER, 0); 143 return (NULL); 144 } 145 146 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT); 147 148 assert(msz > 0); 149 150 if ((ehdr = calloc((size_t) 1, msz)) == NULL) { 151 LIBELF_SET_ERROR(RESOURCE, 0); 152 return (NULL); 153 } 154 155 if (ec == ELFCLASS32) { 156 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; 157 EHDR_INIT(ehdr,32); 158 } else { 159 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; 160 EHDR_INIT(ehdr,64); 161 } 162 163 if (allocate) 164 e->e_flags |= ELF_F_DIRTY; 165 166 if (e->e_cmd == ELF_C_WRITE) 167 return (ehdr); 168 169 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec); 170 (*xlator)((unsigned char*) ehdr, msz, e->e_rawfile, (size_t) 1, 171 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 172 173 if (ec == ELFCLASS32) { 174 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; 175 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; 176 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; 177 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; 178 } else { 179 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; 180 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; 181 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; 182 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; 183 } 184 185 if (shnum >= SHN_LORESERVE || 186 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || 187 strndx == SHN_XINDEX))) { 188 LIBELF_SET_ERROR(HEADER, 0); 189 return (NULL); 190 } 191 192 /* 193 * If extended numbering is being used, read the correct 194 * number of sections and program header entries. 195 */ 196 if ((shnum == 0 && shoff != 0) || phnum == PN_XNUM || strndx == SHN_XINDEX) { 197 if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) 198 return (NULL); 199 } else { 200 /* not using extended numbering */ 201 e->e_u.e_elf.e_nphdr = phnum; 202 e->e_u.e_elf.e_nscn = shnum; 203 e->e_u.e_elf.e_strndx = strndx; 204 } 205 206 return (ehdr); 207 } 208