1 /* $NetBSD: elf_scn.c,v 1.3 2016/02/20 02:43:42 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 <stdint.h> 42 #include <stdlib.h> 43 44 #include "_libelf.h" 45 46 __RCSID("$NetBSD: elf_scn.c,v 1.3 2016/02/20 02:43:42 christos Exp $"); 47 ELFTC_VCSID("Id: elf_scn.c 3177 2015-03-30 18:19:41Z emaste "); 48 49 /* 50 * Load an ELF section table and create a list of Elf_Scn structures. 51 */ 52 int 53 _libelf_load_section_headers(Elf *e, void *ehdr) 54 { 55 Elf_Scn *scn; 56 uint64_t shoff; 57 Elf32_Ehdr *eh32; 58 Elf64_Ehdr *eh64; 59 int ec, swapbytes; 60 unsigned char *src; 61 size_t fsz, i, shnum; 62 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s, 63 size_t _c, int _swap); 64 65 assert(e != NULL); 66 assert(ehdr != NULL); 67 assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0); 68 69 #define CHECK_EHDR(E,EH) do { \ 70 if (shoff > e->e_rawsize || \ 71 fsz != (EH)->e_shentsize || \ 72 shnum > SIZE_MAX / fsz || \ 73 fsz * shnum > e->e_rawsize - shoff) { \ 74 LIBELF_SET_ERROR(HEADER, 0); \ 75 return (0); \ 76 } \ 77 } while (0) 78 79 ec = e->e_class; 80 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1); 81 assert(fsz > 0); 82 83 shnum = e->e_u.e_elf.e_nscn; 84 85 if (ec == ELFCLASS32) { 86 eh32 = (Elf32_Ehdr *) ehdr; 87 shoff = (uint64_t) eh32->e_shoff; 88 CHECK_EHDR(e, eh32); 89 } else { 90 eh64 = (Elf64_Ehdr *) ehdr; 91 shoff = eh64->e_shoff; 92 CHECK_EHDR(e, eh64); 93 } 94 95 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec); 96 97 swapbytes = e->e_byteorder != _libelf_host_byteorder(); 98 if (shoff > SSIZE_MAX) { 99 LIBELF_SET_ERROR(HEADER, 0); 100 return (0); 101 } 102 src = e->e_rawfile + (ssize_t)shoff; 103 104 /* 105 * If the file is using extended numbering then section #0 106 * would have already been read in. 107 */ 108 109 i = 0; 110 if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 111 assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) == 112 STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next)); 113 114 i = 1; 115 src += fsz; 116 } 117 118 for (; i < shnum; i++, src += fsz) { 119 if ((scn = _libelf_allocate_scn(e, i)) == NULL) 120 return (0); 121 122 (*xlator)((void *) &scn->s_shdr, sizeof(scn->s_shdr), 123 src, (size_t) 1, swapbytes); 124 125 if (ec == ELFCLASS32) { 126 scn->s_offset = scn->s_rawoff = 127 scn->s_shdr.s_shdr32.sh_offset; 128 scn->s_size = scn->s_shdr.s_shdr32.sh_size; 129 } else { 130 scn->s_offset = scn->s_rawoff = 131 scn->s_shdr.s_shdr64.sh_offset; 132 scn->s_size = scn->s_shdr.s_shdr64.sh_size; 133 } 134 } 135 136 e->e_flags |= LIBELF_F_SHDRS_LOADED; 137 138 return (1); 139 } 140 141 142 Elf_Scn * 143 elf_getscn(Elf *e, size_t index) 144 { 145 int ec; 146 void *ehdr; 147 Elf_Scn *s; 148 149 if (e == NULL || e->e_kind != ELF_K_ELF || 150 ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) { 151 LIBELF_SET_ERROR(ARGUMENT, 0); 152 return (NULL); 153 } 154 155 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 156 return (NULL); 157 158 if (e->e_cmd != ELF_C_WRITE && 159 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 160 _libelf_load_section_headers(e, ehdr) == 0) 161 return (NULL); 162 163 STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) 164 if (s->s_ndx == index) 165 return (s); 166 167 LIBELF_SET_ERROR(ARGUMENT, 0); 168 return (NULL); 169 } 170 171 size_t 172 elf_ndxscn(Elf_Scn *s) 173 { 174 if (s == NULL) { 175 LIBELF_SET_ERROR(ARGUMENT, 0); 176 return (SHN_UNDEF); 177 } 178 return (s->s_ndx); 179 } 180 181 Elf_Scn * 182 elf_newscn(Elf *e) 183 { 184 int ec; 185 void *ehdr; 186 Elf_Scn *scn; 187 188 if (e == NULL || e->e_kind != ELF_K_ELF) { 189 LIBELF_SET_ERROR(ARGUMENT, 0); 190 return (NULL); 191 } 192 193 if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) { 194 LIBELF_SET_ERROR(CLASS, 0); 195 return (NULL); 196 } 197 198 if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) 199 return (NULL); 200 201 /* 202 * The application may be asking for a new section descriptor 203 * on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We 204 * need to bring in the existing section information before 205 * appending a new one to the list. 206 * 207 * Per the ELF(3) API, an application is allowed to open a 208 * file using ELF_C_READ, mess with its internal structure and 209 * use elf_update(...,ELF_C_NULL) to compute its new layout. 210 */ 211 if (e->e_cmd != ELF_C_WRITE && 212 (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && 213 _libelf_load_section_headers(e, ehdr) == 0) 214 return (NULL); 215 216 if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) { 217 assert(e->e_u.e_elf.e_nscn == 0); 218 if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) == 219 NULL) 220 return (NULL); 221 e->e_u.e_elf.e_nscn++; 222 } 223 224 assert(e->e_u.e_elf.e_nscn > 0); 225 226 if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL) 227 return (NULL); 228 229 e->e_u.e_elf.e_nscn++; 230 231 (void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY); 232 233 return (scn); 234 } 235 236 Elf_Scn * 237 elf_nextscn(Elf *e, Elf_Scn *s) 238 { 239 if (e == NULL || (e->e_kind != ELF_K_ELF) || 240 (s && s->s_elf != e)) { 241 LIBELF_SET_ERROR(ARGUMENT, 0); 242 return (NULL); 243 } 244 245 return (s == NULL ? elf_getscn(e, (size_t) 1) : 246 STAILQ_NEXT(s, s_next)); 247 } 248