Branch data Line data Source code
1 : : /*
2 : : * Constant-time equality testing of memory regions.
3 : : *
4 : : * Authors:
5 : : *
6 : : * James Yonan <james@openvpn.net>
7 : : * Daniel Borkmann <dborkman@redhat.com>
8 : : *
9 : : * This file is provided under a dual BSD/GPLv2 license. When using or
10 : : * redistributing this file, you may do so under either license.
11 : : *
12 : : * GPL LICENSE SUMMARY
13 : : *
14 : : * Copyright(c) 2013 OpenVPN Technologies, Inc. All rights reserved.
15 : : *
16 : : * This program is free software; you can redistribute it and/or modify
17 : : * it under the terms of version 2 of the GNU General Public License as
18 : : * published by the Free Software Foundation.
19 : : *
20 : : * This program is distributed in the hope that it will be useful, but
21 : : * WITHOUT ANY WARRANTY; without even the implied warranty of
22 : : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 : : * General Public License for more details.
24 : : *
25 : : * You should have received a copy of the GNU General Public License
26 : : * along with this program; if not, write to the Free Software
27 : : * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
28 : : * The full GNU General Public License is included in this distribution
29 : : * in the file called LICENSE.GPL.
30 : : *
31 : : * BSD LICENSE
32 : : *
33 : : * Copyright(c) 2013 OpenVPN Technologies, Inc. All rights reserved.
34 : : *
35 : : * Redistribution and use in source and binary forms, with or without
36 : : * modification, are permitted provided that the following conditions
37 : : * are met:
38 : : *
39 : : * * Redistributions of source code must retain the above copyright
40 : : * notice, this list of conditions and the following disclaimer.
41 : : * * Redistributions in binary form must reproduce the above copyright
42 : : * notice, this list of conditions and the following disclaimer in
43 : : * the documentation and/or other materials provided with the
44 : : * distribution.
45 : : * * Neither the name of OpenVPN Technologies nor the names of its
46 : : * contributors may be used to endorse or promote products derived
47 : : * from this software without specific prior written permission.
48 : : *
49 : : * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
50 : : * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
51 : : * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
52 : : * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
53 : : * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
54 : : * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
55 : : * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
56 : : * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
57 : : * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
58 : : * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
59 : : * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
60 : : */
61 : :
62 : : #include <crypto/algapi.h>
63 : :
64 : : #ifndef __HAVE_ARCH_CRYPTO_MEMNEQ
65 : :
66 : : /* Generic path for arbitrary size */
67 : : static inline unsigned long
68 : : __crypto_memneq_generic(const void *a, const void *b, size_t size)
69 : : {
70 : : unsigned long neq = 0;
71 : :
72 : : #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
73 : : while (size >= sizeof(unsigned long)) {
74 : : neq |= *(unsigned long *)a ^ *(unsigned long *)b;
75 : : a += sizeof(unsigned long);
76 : : b += sizeof(unsigned long);
77 : : size -= sizeof(unsigned long);
78 : : }
79 : : #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
80 [ # # ]: 0 : while (size > 0) {
81 : 0 : neq |= *(unsigned char *)a ^ *(unsigned char *)b;
82 : 0 : a += 1;
83 : 0 : b += 1;
84 : 0 : size -= 1;
85 : : }
86 : : return neq;
87 : : }
88 : :
89 : : /* Loop-free fast-path for frequently used 16-byte size */
90 : : static inline unsigned long __crypto_memneq_16(const void *a, const void *b)
91 : : {
92 : : #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
93 : : if (sizeof(unsigned long) == 8)
94 : : return ((*(unsigned long *)(a) ^ *(unsigned long *)(b))
95 : : | (*(unsigned long *)(a+8) ^ *(unsigned long *)(b+8)));
96 : : else if (sizeof(unsigned int) == 4)
97 : : return ((*(unsigned int *)(a) ^ *(unsigned int *)(b))
98 : : | (*(unsigned int *)(a+4) ^ *(unsigned int *)(b+4))
99 : : | (*(unsigned int *)(a+8) ^ *(unsigned int *)(b+8))
100 : : | (*(unsigned int *)(a+12) ^ *(unsigned int *)(b+12)));
101 : : else
102 : : #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
103 : 0 : return ((*(unsigned char *)(a) ^ *(unsigned char *)(b))
104 : 0 : | (*(unsigned char *)(a+1) ^ *(unsigned char *)(b+1))
105 : 0 : | (*(unsigned char *)(a+2) ^ *(unsigned char *)(b+2))
106 : 0 : | (*(unsigned char *)(a+3) ^ *(unsigned char *)(b+3))
107 : 0 : | (*(unsigned char *)(a+4) ^ *(unsigned char *)(b+4))
108 : 0 : | (*(unsigned char *)(a+5) ^ *(unsigned char *)(b+5))
109 : 0 : | (*(unsigned char *)(a+6) ^ *(unsigned char *)(b+6))
110 : 0 : | (*(unsigned char *)(a+7) ^ *(unsigned char *)(b+7))
111 : 0 : | (*(unsigned char *)(a+8) ^ *(unsigned char *)(b+8))
112 : 0 : | (*(unsigned char *)(a+9) ^ *(unsigned char *)(b+9))
113 : 0 : | (*(unsigned char *)(a+10) ^ *(unsigned char *)(b+10))
114 : 0 : | (*(unsigned char *)(a+11) ^ *(unsigned char *)(b+11))
115 : 0 : | (*(unsigned char *)(a+12) ^ *(unsigned char *)(b+12))
116 : 0 : | (*(unsigned char *)(a+13) ^ *(unsigned char *)(b+13))
117 : 0 : | (*(unsigned char *)(a+14) ^ *(unsigned char *)(b+14))
118 : 0 : | (*(unsigned char *)(a+15) ^ *(unsigned char *)(b+15)));
119 : : }
120 : :
121 : : /* Compare two areas of memory without leaking timing information,
122 : : * and with special optimizations for common sizes. Users should
123 : : * not call this function directly, but should instead use
124 : : * crypto_memneq defined in crypto/algapi.h.
125 : : */
126 : 0 : noinline unsigned long __crypto_memneq(const void *a, const void *b,
127 : : size_t size)
128 : : {
129 [ # # ]: 0 : switch (size) {
130 : : case 16:
131 : 0 : return __crypto_memneq_16(a, b);
132 : : default:
133 : : return __crypto_memneq_generic(a, b, size);
134 : : }
135 : : }
136 : : EXPORT_SYMBOL(__crypto_memneq);
137 : :
138 : : #endif /* __HAVE_ARCH_CRYPTO_MEMNEQ */
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