1 /* $NetBSD: elf_scn.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2006,2008-2010 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 #include <sys/queue.h> 35 36 #include <assert.h> 37 #include <errno.h> 38 #include <gelf.h> 39 #include <libelf.h> 40 #include <stddef.h> 41 #include <stdlib.h> 42 43 #include "_libelf.h" 44 45 __RCSID("$NetBSD: elf_scn.c,v 1.2 2014/03/09 16:58:04 christos Exp $"); 46 ELFTC_VCSID("Id: elf_scn.c 2225 2011-11-26 18:55:54Z jkoshy "); 47 48 /* 49 * Load an ELF section table and create a list of Elf_Scn structures. 50 */ 51 int 52 _libelf_load_section_headers(Elf *e, void *ehdr) 53 { 54 int ec, swapbytes; 55 size_t fsz, i, shnum; 56 uint64_t shoff; 57 char *src; 58 Elf32_Ehdr *eh32; 59 Elf64_Ehdr *eh64; 60 Elf_Scn *scn; 61 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap); 62 63 assert(e != NULL); 64 assert(ehdr != NULL); 65 assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0); 66 67 #define CHECK_EHDR(E,EH) do { \ 68 if (fsz != (EH)->e_shentsize || \ 69 shoff + fsz * shnum > e->e_rawsize) { \ 70 LIBELF_SET_ERROR(HEADER, 0); \ 71 return (0); \ 72 } \ 73 } while (0) 74 75 ec = e->e_class; 76 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1); 77 assert(fsz > 0); 78 79 shnum = e->e_u.e_elf.e_nscn; 80 81 if (ec == ELFCLASS32) { 82 eh32 = (Elf32_Ehdr *) ehdr; 83 shoff = (uint64_t) eh32->e_shoff; 84 CHECK_EHDR(e, eh32); 85 } else { 86 eh64 = (Elf64_Ehdr *) ehdr; 87 shoff = eh64->e_shoff; 88 CHECK_EHDR(e, eh64); 89 } 90 91 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 92 93 swapbytes = e->e_byteorder != _libelf_host_byteorder(); 94 if (shoff > SSIZE_MAX) { 95 LIBELF_SET_ERROR(HEADER, 0); 96 return (0); 97 } 98 src = e->e_rawfile + (ssize_t)shoff; 99 100 /* 101 * If the file is using extended numbering then section #0 102 * would have already been read in. 103 */ 104 105 i = 0; 106 if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 107 assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) == 108 STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next)); 109 110 i = 1; 111 src += fsz; 112 } 113 114 for (; i < shnum; i++, src += fsz) { 115 if ((scn = _libelf_allocate_scn(e, i)) == NULL) 116 return (0); 117 118 (*xlator)((void *) &scn->s_shdr, sizeof(scn->s_shdr), src, 119 (size_t) 1, swapbytes); 120 121 if (ec == ELFCLASS32) { 122 scn->s_offset = scn->s_rawoff = 123 scn->s_shdr.s_shdr32.sh_offset; 124 scn->s_size = scn->s_shdr.s_shdr32.sh_size; 125 } else { 126 scn->s_offset = scn->s_rawoff = 127 scn->s_shdr.s_shdr64.sh_offset; 128 scn->s_size = scn->s_shdr.s_shdr64.sh_size; 129 } 130 } 131 132 e->e_flags |= LIBELF_F_SHDRS_LOADED; 133 134 return (1); 135 } 136 137 138 Elf_Scn * 139 elf_getscn(Elf *e, size_t index) 140 { 141 int ec; 142 void *ehdr; 143 Elf_Scn *s; 144 145 if (e == NULL || e->e_kind != ELF_K_ELF || 146 ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) { 147 LIBELF_SET_ERROR(ARGUMENT, 0); 148 return (NULL); 149 } 150 151 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 152 return (NULL); 153 154 if (e->e_cmd != ELF_C_WRITE && 155 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 156 _libelf_load_section_headers(e, ehdr) == 0) 157 return (NULL); 158 159 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) 160 if (s->s_ndx == index) 161 return (s); 162 163 LIBELF_SET_ERROR(ARGUMENT, 0); 164 return (NULL); 165 } 166 167 size_t 168 elf_ndxscn(Elf_Scn *s) 169 { 170 if (s == NULL) { 171 LIBELF_SET_ERROR(ARGUMENT, 0); 172 return (SHN_UNDEF); 173 } 174 return (s->s_ndx); 175 } 176 177 Elf_Scn * 178 elf_newscn(Elf *e) 179 { 180 int ec; 181 void *ehdr; 182 Elf_Scn *scn; 183 184 if (e == NULL || e->e_kind != ELF_K_ELF) { 185 LIBELF_SET_ERROR(ARGUMENT, 0); 186 return (NULL); 187 } 188 189 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) { 190 LIBELF_SET_ERROR(CLASS, 0); 191 return (NULL); 192 } 193 194 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 195 return (NULL); 196 197 /* 198 * The application may be asking for a new section descriptor 199 * on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We 200 * need to bring in the existing section information before 201 * appending a new one to the list. 202 * 203 * Per the ELF(3) API, an application is allowed to open a 204 * file using ELF_C_READ, mess with its internal structure and 205 * use elf_update(...,ELF_C_NULL) to compute its new layout. 206 */ 207 if (e->e_cmd != ELF_C_WRITE && 208 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 209 _libelf_load_section_headers(e, ehdr) == 0) 210 return (NULL); 211 212 if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 213 assert(e->e_u.e_elf.e_nscn == 0); 214 if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) == 215 NULL) 216 return (NULL); 217 e->e_u.e_elf.e_nscn++; 218 } 219 220 assert(e->e_u.e_elf.e_nscn > 0); 221 222 if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL) 223 return (NULL); 224 225 e->e_u.e_elf.e_nscn++; 226 227 (void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY); 228 229 return (scn); 230 } 231 232 Elf_Scn * 233 elf_nextscn(Elf *e, Elf_Scn *s) 234 { 235 if (e == NULL || (e->e_kind != ELF_K_ELF) || 236 (s && s->s_elf != e)) { 237 LIBELF_SET_ERROR(ARGUMENT, 0); 238 return (NULL); 239 } 240 241 return (s == NULL ? elf_getscn(e, (size_t) 1) : 242 STAILQ_NEXT(s, s_next)); 243 } 244