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
30 #include "_libelf.h"
31
32 ELFTC_VCSID("$Id: libelf_xlate.c 3732 2019-04-22 11:08:38Z jkoshy $");
33
34 /*
35 * Translate to/from the file representation of ELF objects.
36 *
37 * Translation could potentially involve the following
38 * transformations:
39 *
40 * - an endianness conversion,
41 * - a change of layout, as the file representation of ELF objects
42 * can differ from their in-memory representation.
43 * - a change in representation due to a layout version change.
44 */
45
46 Elf_Data *
_libelf_xlate(Elf_Data * dst,const Elf_Data * src,unsigned int encoding,int elfclass,int elfmachine,int direction)47 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
48 int elfclass, int elfmachine, int direction)
49 {
50 int byteswap;
51 size_t cnt, dsz, fsz, msz;
52 uintptr_t sb, se, db, de;
53 _libelf_translator_function *xlator;
54
55 if (encoding == ELFDATANONE)
56 encoding = LIBELF_PRIVATE(byteorder);
57
58 if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
59 dst == NULL || src == NULL || dst == src) {
60 LIBELF_SET_ERROR(ARGUMENT, 0);
61 return (NULL);
62 }
63
64 assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
65 assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
66
67 if (dst->d_version != src->d_version) {
68 LIBELF_SET_ERROR(UNIMPL, 0);
69 return (NULL);
70 }
71
72 if (src->d_buf == NULL || dst->d_buf == NULL) {
73 LIBELF_SET_ERROR(DATA, 0);
74 return (NULL);
75 }
76
77 if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
78 LIBELF_SET_ERROR(DATA, 0);
79 return (NULL);
80 }
81
82 if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
83 (src->d_type, (size_t) 1, src->d_version)) == 0)
84 return (NULL);
85
86 if ((msz = _libelf_msize(src->d_type, elfclass, src->d_version)) == 0)
87 return (NULL);
88
89 if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
90 LIBELF_SET_ERROR(DATA, 0);
91 return (NULL);
92 }
93
94 /*
95 * Determine the number of objects that need to be converted, and
96 * the space required for the converted objects in the destination
97 * buffer.
98 */
99 if (direction == ELF_TOMEMORY) {
100 cnt = (size_t) src->d_size / fsz;
101 dsz = cnt * msz;
102 } else {
103 cnt = (size_t) src->d_size / msz;
104 dsz = cnt * fsz;
105 }
106
107 if (dst->d_size < dsz) {
108 LIBELF_SET_ERROR(DATA, 0);
109 return (NULL);
110 }
111
112 sb = (uintptr_t) src->d_buf;
113 se = sb + (size_t) src->d_size;
114 db = (uintptr_t) dst->d_buf;
115 de = db + (size_t) dst->d_size;
116
117 /*
118 * Check for overlapping buffers. Note that db == sb is
119 * allowed.
120 */
121 if (db != sb && de > sb && se > db) {
122 LIBELF_SET_ERROR(DATA, 0);
123 return (NULL);
124 }
125
126 if ((direction == ELF_TOMEMORY ? db : sb) %
127 _libelf_malign(src->d_type, elfclass)) {
128 LIBELF_SET_ERROR(DATA, 0);
129 return (NULL);
130 }
131
132 dst->d_type = src->d_type;
133 dst->d_size = dsz;
134
135 byteswap = encoding != LIBELF_PRIVATE(byteorder);
136
137 if (src->d_size == 0 ||
138 (db == sb && !byteswap && fsz == msz))
139 return (dst); /* nothing more to do */
140
141 xlator = _libelf_get_translator(src->d_type, direction, elfclass,
142 elfmachine);
143 if (!xlator(dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
144 LIBELF_SET_ERROR(DATA, 0);
145 return (NULL);
146 }
147
148 return (dst);
149 }
150