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 <libelf.h> 29 #include <stdint.h> 30 31 #include "_libelf.h" 32 33 ELFTC_VCSID("$Id: libelf_xlate.c,v 1.2 2020/05/18 06:46:23 jsg Exp $"); 34 35 /* 36 * Translate to/from the file representation of ELF objects. 37 * 38 * Translation could potentially involve the following 39 * transformations: 40 * 41 * - an endianness conversion, 42 * - a change of layout, as the file representation of ELF objects 43 * can differ from their in-memory representation. 44 * - a change in representation due to a layout version change. 45 */ 46 47 Elf_Data * 48 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding, 49 int elfclass, int elfmachine, int direction) 50 { 51 int byteswap; 52 size_t cnt, dsz, fsz, msz; 53 uintptr_t sb, se, db, de; 54 _libelf_translator_function *xlator; 55 56 if (encoding == ELFDATANONE) 57 encoding = LIBELF_PRIVATE(byteorder); 58 59 if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) || 60 dst == NULL || src == NULL || dst == src) { 61 LIBELF_SET_ERROR(ARGUMENT, 0); 62 return (NULL); 63 } 64 65 assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64); 66 assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY); 67 68 if (dst->d_version != src->d_version) { 69 LIBELF_SET_ERROR(UNIMPL, 0); 70 return (NULL); 71 } 72 73 if (src->d_buf == NULL || dst->d_buf == NULL) { 74 LIBELF_SET_ERROR(DATA, 0); 75 return (NULL); 76 } 77 78 if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) { 79 LIBELF_SET_ERROR(DATA, 0); 80 return (NULL); 81 } 82 83 if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize) 84 (src->d_type, (size_t) 1, src->d_version)) == 0) 85 return (NULL); 86 87 if ((msz = _libelf_msize(src->d_type, elfclass, src->d_version)) == 0) 88 return (NULL); 89 90 if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) { 91 LIBELF_SET_ERROR(DATA, 0); 92 return (NULL); 93 } 94 95 /* 96 * Determine the number of objects that need to be converted, and 97 * the space required for the converted objects in the destination 98 * buffer. 99 */ 100 if (direction == ELF_TOMEMORY) { 101 cnt = (size_t) src->d_size / fsz; 102 dsz = cnt * msz; 103 } else { 104 cnt = (size_t) src->d_size / msz; 105 dsz = cnt * fsz; 106 } 107 108 if (dst->d_size < dsz) { 109 LIBELF_SET_ERROR(DATA, 0); 110 return (NULL); 111 } 112 113 sb = (uintptr_t) src->d_buf; 114 se = sb + (size_t) src->d_size; 115 db = (uintptr_t) dst->d_buf; 116 de = db + (size_t) dst->d_size; 117 118 /* 119 * Check for overlapping buffers. Note that db == sb is 120 * allowed. 121 */ 122 if (db != sb && de > sb && se > db) { 123 LIBELF_SET_ERROR(DATA, 0); 124 return (NULL); 125 } 126 127 if ((direction == ELF_TOMEMORY ? db : sb) % 128 _libelf_malign(src->d_type, elfclass)) { 129 LIBELF_SET_ERROR(DATA, 0); 130 return (NULL); 131 } 132 133 dst->d_type = src->d_type; 134 dst->d_size = dsz; 135 136 byteswap = encoding != LIBELF_PRIVATE(byteorder); 137 138 if (src->d_size == 0 || 139 (db == sb && !byteswap && fsz == msz)) 140 return (dst); /* nothing more to do */ 141 142 xlator = _libelf_get_translator(src->d_type, direction, elfclass, 143 elfmachine); 144 if (!xlator(dst->d_buf, dsz, src->d_buf, cnt, byteswap)) { 145 LIBELF_SET_ERROR(DATA, 0); 146 return (NULL); 147 } 148 149 return (dst); 150 } 151