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 *
_libelf_xlate(Elf_Data * dst,const Elf_Data * src,unsigned int encoding,int elfclass,int elfmachine,int direction)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