1/*- 2 * Copyright (c) 2006 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__FBSDID("$FreeBSD$"); 29 30#include <assert.h> 31#include <errno.h> 32#include <gelf.h> 33#include <libelf.h> 34#include <stdlib.h> 35 36#include "_libelf.h" 37 38/* 39 * Load an ELF section table and create a list of Elf_Scn structures. 40 */ 41int 42_libelf_load_scn(Elf *e, void *ehdr) 43{ 44 int ec, swapbytes; 45 size_t fsz, i, shnum; 46 uint64_t shoff; 47 char *src; 48 Elf32_Ehdr *eh32; 49 Elf64_Ehdr *eh64; 50 Elf_Scn *scn; 51 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); 52 53 assert(e != NULL); 54 assert(ehdr != NULL); 55 assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0); 56 57#define CHECK_EHDR(E,EH) do { \ 58 if (fsz != (EH)->e_shentsize || \ 59 shoff + fsz * shnum > e->e_rawsize) { \ 60 LIBELF_SET_ERROR(HEADER, 0); \ 61 return (0); \ 62 } \ 63 } while (0) 64 65 ec = e->e_class; 66 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1); 67 assert(fsz > 0); 68 69 shnum = e->e_u.e_elf.e_nscn; 70 71 if (ec == ELFCLASS32) { 72 eh32 = (Elf32_Ehdr *) ehdr; 73 shoff = (uint64_t) eh32->e_shoff; 74 CHECK_EHDR(e, eh32); 75 } else { 76 eh64 = (Elf64_Ehdr *) ehdr; 77 shoff = eh64->e_shoff; 78 CHECK_EHDR(e, eh64); 79 } 80 81 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 82 83 swapbytes = e->e_byteorder != LIBELF_PRIVATE(byteorder); 84 src = e->e_rawfile + shoff; 85 86 /* 87 * If the file is using extended numbering then section #0 88 * would have already been read in. 89 */ 90 91 i = 0; 92 if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 93 assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) == 94 STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next)); 95 96 i = 1; 97 src += fsz; 98 } 99 100 for (; i < shnum; i++, src += fsz) { 101 if ((scn = _libelf_allocate_scn(e, i)) == NULL) 102 return (0); 103 104 (*xlator)((char *) &scn->s_shdr, sizeof(scn->s_shdr), src, 105 (size_t) 1, swapbytes); 106 107 if (ec == ELFCLASS32) { 108 scn->s_offset = scn->s_rawoff = 109 scn->s_shdr.s_shdr32.sh_offset; 110 scn->s_size = scn->s_shdr.s_shdr32.sh_size; 111 } else { 112 scn->s_offset = scn->s_rawoff = 113 scn->s_shdr.s_shdr64.sh_offset; 114 scn->s_size = scn->s_shdr.s_shdr64.sh_size; 115 } 116 } 117 118 e->e_flags |= LIBELF_F_SHDRS_LOADED; 119 120 return (1); 121} 122 123 124Elf_Scn * 125elf_getscn(Elf *e, size_t index) 126{ 127 int ec; 128 void *ehdr; 129 Elf_Scn *s; 130 131 if (e == NULL || e->e_kind != ELF_K_ELF || 132 ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) { 133 LIBELF_SET_ERROR(ARGUMENT, 0); 134 return (NULL); 135 } 136 137 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 138 return (NULL); 139 140 if (e->e_cmd != ELF_C_WRITE && 141 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 142 _libelf_load_scn(e, ehdr) == 0) 143 return (NULL); 144 145 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) 146 if (s->s_ndx == index) 147 return (s); 148 149 LIBELF_SET_ERROR(ARGUMENT, 0); 150 return (NULL); 151} 152 153size_t 154elf_ndxscn(Elf_Scn *s) 155{ 156 if (s == NULL) { 157 LIBELF_SET_ERROR(ARGUMENT, 0); 158 return (SHN_UNDEF); 159 } 160 return (s->s_ndx); 161} 162 163Elf_Scn * 164elf_newscn(Elf *e) 165{ 166 int ec; 167 void *ehdr; 168 Elf_Scn *scn; 169 170 if (e == NULL || e->e_kind != ELF_K_ELF) { 171 LIBELF_SET_ERROR(ARGUMENT, 0); 172 return (NULL); 173 } 174 175 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) { 176 LIBELF_SET_ERROR(CLASS, 0); 177 return (NULL); 178 } 179 180 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 181 return (NULL); 182 183 /* 184 * The application may be asking for a new section descriptor 185 * on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We 186 * need to bring in the existing section information before 187 * appending a new one to the list. 188 * 189 * Per the ELF(3) API, an application is allowed to open a 190 * file using ELF_C_READ, mess with its internal structure and 191 * use elf_update(...,ELF_C_NULL) to compute its new layout. 192 */ 193 if (e->e_cmd != ELF_C_WRITE && 194 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 195 _libelf_load_scn(e, ehdr) == 0) 196 return (NULL); 197 198 if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 199 assert(e->e_u.e_elf.e_nscn == 0); 200 if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) == 201 NULL) 202 return (NULL); 203 e->e_u.e_elf.e_nscn++; 204 } 205 206 assert(e->e_u.e_elf.e_nscn > 0); 207 208 if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL) 209 return (NULL); 210 211 e->e_u.e_elf.e_nscn++; 212 213 (void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY); 214 215 return (scn); 216} 217 218Elf_Scn * 219elf_nextscn(Elf *e, Elf_Scn *s) 220{ 221 if (e == NULL || (e->e_kind != ELF_K_ELF) || 222 (s && s->s_elf != e)) { 223 LIBELF_SET_ERROR(ARGUMENT, 0); 224 return (NULL); 225 } 226 227 return (s == NULL ? elf_getscn(e, (size_t) 1) : 228 STAILQ_NEXT(s, s_next)); 229} 230