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 3732 2019-04-22 11:08:38Z jkoshy $"); 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 size_t fsz; 45 Elf_Scn *scn; 46 uint32_t shtype; 47 _libelf_translator_function *xlator; 48 49 assert(RB_EMPTY(&e->e_u.e_elf.e_scn)); 50 51 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1); 52 assert(fsz > 0); 53 54 if (shoff + fsz < shoff) { /* Numeric overflow. */ 55 LIBELF_SET_ERROR(HEADER, 0); 56 return (0); 57 } 58 59 if ((uint64_t) e->e_rawsize < shoff + fsz) { 60 LIBELF_SET_ERROR(HEADER, 0); 61 return (0); 62 } 63 64 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL) 65 return (0); 66 67 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec, 68 _libelf_elfmachine(e)); 69 (*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr), 70 (unsigned char *) e->e_rawfile + shoff, (size_t) 1, 71 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 72 73 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \ 74 scn->s_shdr.s_shdr64.M) 75 76 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) { 77 LIBELF_SET_ERROR(SECTION, 0); 78 return (0); 79 } 80 81 e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size); 82 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum : 83 GET_SHDR_MEMBER(sh_info); 84 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx : 85 GET_SHDR_MEMBER(sh_link); 86 #undef GET_SHDR_MEMBER 87 88 return (1); 89 } 90 91 #define EHDR_INIT(E,SZ) do { \ 92 Elf##SZ##_Ehdr *eh = (E); \ 93 eh->e_ident[EI_MAG0] = ELFMAG0; \ 94 eh->e_ident[EI_MAG1] = ELFMAG1; \ 95 eh->e_ident[EI_MAG2] = ELFMAG2; \ 96 eh->e_ident[EI_MAG3] = ELFMAG3; \ 97 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \ 98 eh->e_ident[EI_DATA] = ELFDATANONE; \ 99 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \ 100 eh->e_machine = EM_NONE; \ 101 eh->e_type = ELF_K_NONE; \ 102 eh->e_version = LIBELF_PRIVATE(version); \ 103 } while (0) 104 105 void * 106 _libelf_ehdr(Elf *e, int ec, int allocate) 107 { 108 void *ehdr; 109 size_t fsz, msz; 110 uint16_t phnum, shnum, strndx; 111 uint64_t shoff; 112 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 113 size_t _c, int _swap); 114 115 assert(ec == ELFCLASS32 || ec == ELFCLASS64); 116 117 if (e == NULL || e->e_kind != ELF_K_ELF) { 118 LIBELF_SET_ERROR(ARGUMENT, 0); 119 return (NULL); 120 } 121 122 if (e->e_class != ELFCLASSNONE && e->e_class != ec) { 123 LIBELF_SET_ERROR(CLASS, 0); 124 return (NULL); 125 } 126 127 if (e->e_version != EV_CURRENT) { 128 LIBELF_SET_ERROR(VERSION, 0); 129 return (NULL); 130 } 131 132 if (e->e_class == ELFCLASSNONE) 133 e->e_class = ec; 134 135 if (ec == ELFCLASS32) 136 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32; 137 else 138 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64; 139 140 if (ehdr != NULL) /* already have a translated ehdr */ 141 return (ehdr); 142 143 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); 144 assert(fsz > 0); 145 146 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < (off_t) fsz) { 147 LIBELF_SET_ERROR(HEADER, 0); 148 return (NULL); 149 } 150 151 if ((msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT)) == 0) 152 return (NULL); 153 154 if ((ehdr = calloc((size_t) 1, msz)) == NULL) { 155 LIBELF_SET_ERROR(RESOURCE, 0); 156 return (NULL); 157 } 158 159 if (ec == ELFCLASS32) { 160 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr; 161 EHDR_INIT(ehdr,32); 162 } else { 163 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr; 164 EHDR_INIT(ehdr,64); 165 } 166 167 if (allocate) 168 e->e_flags |= ELF_F_DIRTY; 169 170 if (e->e_cmd == ELF_C_WRITE) 171 return (ehdr); 172 173 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec, 174 _libelf_elfmachine(e)); 175 (*xlator)((unsigned char*) ehdr, msz, e->e_rawfile, (size_t) 1, 176 e->e_byteorder != LIBELF_PRIVATE(byteorder)); 177 178 if (ec == ELFCLASS32) { 179 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum; 180 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum; 181 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff; 182 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx; 183 } else { 184 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum; 185 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum; 186 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff; 187 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx; 188 } 189 190 if (shnum >= SHN_LORESERVE || 191 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM || 192 strndx == SHN_XINDEX))) { 193 LIBELF_SET_ERROR(HEADER, 0); 194 return (NULL); 195 } 196 197 /* 198 * If extended numbering is being used, read the correct 199 * number of sections and program header entries. 200 */ 201 if ((shnum == 0 && shoff != 0) || phnum == PN_XNUM || strndx == SHN_XINDEX) { 202 if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0) 203 return (NULL); 204 } else { 205 /* not using extended numbering */ 206 e->e_u.e_elf.e_nphdr = phnum; 207 e->e_u.e_elf.e_nscn = shnum; 208 e->e_u.e_elf.e_strndx = strndx; 209 } 210 211 return (ehdr); 212 } 213