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
33ELFTC_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
47Elf_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