1 /* $NetBSD: libelf_ehdr.c,v 1.3 2016/02/20 02:43:42 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 1.3 2016/02/20 02:43:42 christos Exp $"); 43 ELFTC_VCSID("Id: libelf_ehdr.c 3174 2015-03-27 17:13:41Z emaste "); 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)(unsigned char *_d, size_t _dsz, unsigned char *_s, 56 size_t _c, int _swap); 57 uint32_t shtype; 58 59 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn)); 60 61 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); 62 assert(fsz > 0); 63 64 if (e->e_rawsize < shoff + fsz) { /* raw file too small */ 65 LIBELF_SET_ERROR(HEADER, 0); 66 return (0); 67 } 68 69 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) 70 return (0); 71 72 if (shoff > SSIZE_MAX) { 73 LIBELF_SET_ERROR(HEADER, 0); 74 return (0); 75 } 76 77 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 78 (*xlator)((void *) &scn->s_shdr, sizeof(scn->s_shdr), 79 (unsigned char *) e->e_rawfile + shoff, (size_t) 1, 80 e->e_byteorder != _libelf_host_byteorder()); 81 82 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ 83 scn->s_shdr.s_shdr64.M) 84 85 if (GET_SHDR_MEMBER(sh_size) > UINT_MAX) { 86 LIBELF_SET_ERROR(HEADER, 0); 87 return (0); 88 } 89 90 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { 91 LIBELF_SET_ERROR(SECTION, 0); 92 return (0); 93 } 94 95 e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size); 96 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : 97 GET_SHDR_MEMBER(sh_info); 98 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : 99 GET_SHDR_MEMBER(sh_link); 100 #undef GET_SHDR_MEMBER 101 102 return (1); 103 } 104 105 #define EHDR_INIT(E,SZ) do { \ 106 Elf##SZ##_Ehdr *eh = (E); \ 107 eh->e_ident[EI_MAG0] = ELFMAG0; \ 108 eh->e_ident[EI_MAG1] = ELFMAG1; \ 109 eh->e_ident[EI_MAG2] = ELFMAG2; \ 110 eh->e_ident[EI_MAG3] = ELFMAG3; \ 111 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ 112 eh->e_ident[EI_DATA] = ELFDATANONE; \ 113 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \ 114 eh->e_machine = EM_NONE; \ 115 eh->e_type = ELF_K_NONE; \ 116 eh->e_version = LIBELF_PRIVATE(version); \ 117 } while (/*CONSTCOND*/0) 118 119 void * 120 _libelf_ehdr(Elf *e, int ec, int allocate) 121 { 122 void *ehdr; 123 size_t fsz, msz; 124 uint16_t phnum, shnum, strndx; 125 uint64_t shoff; 126 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 127 size_t _c, int _swap); 128 129 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 130 131 if (e == NULL || e->e_kind != ELF_K_ELF) { 132 LIBELF_SET_ERROR(ARGUMENT, 0); 133 return (NULL); 134 } 135 136 if (e->e_class != ELFCLASSNONE && e->e_class != ec) { 137 LIBELF_SET_ERROR(CLASS, 0); 138 return (NULL); 139 } 140 141 if (e->e_version != EV_CURRENT) { 142 LIBELF_SET_ERROR(VERSION, 0); 143 return (NULL); 144 } 145 146 if (e->e_class == ELFCLASSNONE) 147 e->e_class = ec; 148 149 if (ec == ELFCLASS32) 150 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; 151 else 152 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; 153 154 if (ehdr != NULL) /* already have a translated ehdr */ 155 return (ehdr); 156 157 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 158 assert(fsz > 0); 159 160 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) { 161 LIBELF_SET_ERROR(HEADER, 0); 162 return (NULL); 163 } 164 165 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT); 166 167 assert(msz > 0); 168 169 if ((ehdr = calloc((size_t) 1, msz)) == NULL) { 170 LIBELF_SET_ERROR(RESOURCE, 0); 171 return (NULL); 172 } 173 174 if (ec == ELFCLASS32) { 175 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; 176 EHDR_INIT(ehdr,32); 177 } else { 178 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; 179 EHDR_INIT(ehdr,64); 180 } 181 182 if (allocate) 183 e->e_flags |= ELF_F_DIRTY; 184 185 if (e->e_cmd == ELF_C_WRITE) 186 return (ehdr); 187 188 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec); 189 (*xlator)((void *)ehdr, msz, e->e_rawfile, (size_t) 1, 190 e->e_byteorder != _libelf_host_byteorder()); 191 192 /* 193 * If extended numbering is being used, read the correct 194 * number of sections and program header entries. 195 */ 196 if (ec == ELFCLASS32) { 197 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; 198 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; 199 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; 200 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; 201 } else { 202 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; 203 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; 204 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; 205 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; 206 } 207 208 if (shnum >= SHN_LORESERVE || 209 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || 210 strndx == SHN_XINDEX))) { 211 LIBELF_SET_ERROR(HEADER, 0); 212 return (NULL); 213 } 214 215 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */ 216 e->e_u.e_elf.e_nphdr = phnum; 217 e->e_u.e_elf.e_nscn = shnum; 218 e->e_u.e_elf.e_strndx = strndx; 219 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) 220 return (NULL); 221 222 return (ehdr); 223 } 224