xref: /freebsd/contrib/elftoolchain/libelf/libelf_xlate.c (revision 13ea0450a9c8742119d36f3bf8f47accdce46e54)
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 3632 2018-10-10 21:12:43Z 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 *
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 	msz = _libelf_msize(src->d_type, elfclass, src->d_version);
87 
88 	assert(msz > 0);
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