1 /* $NetBSD: libelf_xlate.c,v 1.5 2024/03/03 17:37:34 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2006,2008 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
35 #include <assert.h>
36 #include <libelf.h>
37
38 #include "_libelf.h"
39
40 __RCSID("$NetBSD: libelf_xlate.c,v 1.5 2024/03/03 17:37:34 christos Exp $");
41 ELFTC_VCSID("Id: libelf_xlate.c 3977 2022-05-01 06:45:34Z jkoshy");
42
43 /*
44 * Translate to/from the file representation of ELF objects.
45 *
46 * Translation could potentially involve the following
47 * transformations:
48 *
49 * - an endianness conversion,
50 * - a change of layout, as the file representation of ELF objects
51 * can differ from their in-memory representation.
52 * - a change in representation due to a layout version change.
53 */
54
55 Elf_Data *
_libelf_xlate(Elf_Data * dst,const Elf_Data * src,unsigned int encoding,int elfclass,int elfmachine,int direction)56 _libelf_xlate(Elf_Data *dst, const Elf_Data *src, unsigned int encoding,
57 int elfclass, int elfmachine, int direction)
58 {
59 int byteswap;
60 size_t cnt, dsz, fsz, msz;
61 uintptr_t sb, se, db, de;
62 _libelf_translator_function *xlator;
63
64 if (encoding == ELFDATANONE)
65 encoding = LIBELF_PRIVATE(byteorder);
66
67 if ((encoding != ELFDATA2LSB && encoding != ELFDATA2MSB) ||
68 dst == NULL || src == NULL || dst == src) {
69 LIBELF_SET_ERROR(ARGUMENT, 0);
70 return (NULL);
71 }
72
73 assert(elfclass == ELFCLASS32 || elfclass == ELFCLASS64);
74 assert(direction == ELF_TOFILE || direction == ELF_TOMEMORY);
75
76 if (dst->d_version != src->d_version) {
77 LIBELF_SET_ERROR(UNIMPL, 0);
78 return (NULL);
79 }
80
81 if (src->d_buf == NULL || dst->d_buf == NULL) {
82 LIBELF_SET_ERROR(DATA, 0);
83 return (NULL);
84 }
85
86 if ((int) src->d_type < 0 || src->d_type >= ELF_T_NUM) {
87 LIBELF_SET_ERROR(DATA, 0);
88 return (NULL);
89 }
90
91 if ((fsz = (elfclass == ELFCLASS32 ? elf32_fsize : elf64_fsize)
92 (src->d_type, (size_t) 1, src->d_version)) == 0)
93 return (NULL);
94
95 if ((msz = _libelf_msize(src->d_type, elfclass, src->d_version)) == 0)
96 return (NULL);
97
98 if (src->d_size % (direction == ELF_TOMEMORY ? fsz : msz)) {
99 LIBELF_SET_ERROR(DATA, 0);
100 return (NULL);
101 }
102
103 /*
104 * Determine the number of objects that need to be converted, and
105 * the space required for the converted objects in the destination
106 * buffer.
107 */
108 if (direction == ELF_TOMEMORY) {
109 cnt = (size_t) src->d_size / fsz;
110 dsz = cnt * msz;
111 } else {
112 cnt = (size_t) src->d_size / msz;
113 dsz = cnt * fsz;
114 }
115
116 if (dst->d_size < dsz) {
117 LIBELF_SET_ERROR(DATA, 0);
118 return (NULL);
119 }
120
121 sb = (uintptr_t) src->d_buf;
122 se = sb + (size_t) src->d_size;
123 db = (uintptr_t) dst->d_buf;
124 de = db + (size_t) dst->d_size;
125
126 /*
127 * Check for overlapping buffers. Note that db == sb is
128 * allowed.
129 */
130 if (db != sb && de > sb && se > db) {
131 LIBELF_SET_ERROR(DATA, 0);
132 return (NULL);
133 }
134
135 if ((direction == ELF_TOMEMORY ? db : sb) %
136 _libelf_malign(src->d_type, elfclass)) {
137 LIBELF_SET_ERROR(DATA, 0);
138 return (NULL);
139 }
140
141 dst->d_type = src->d_type;
142 dst->d_size = dsz;
143
144 byteswap = encoding != LIBELF_PRIVATE(byteorder);
145
146 if (src->d_size == 0 ||
147 (db == sb && !byteswap && fsz == msz))
148 return (dst); /* nothing more to do */
149
150 xlator = _libelf_get_translator(src->d_type, direction, elfclass,
151 elfmachine);
152 if (!xlator(dst->d_buf, dsz, src->d_buf, cnt, byteswap)) {
153 LIBELF_SET_ERROR(DATA, 0);
154 return (NULL);
155 }
156
157 return (dst);
158 }
159