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6bf37e5a JY |
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; | |
fe8c8a12 | 75 | OPTIMIZER_HIDE_VAR(neq); |
6bf37e5a JY |
76 | a += sizeof(unsigned long); |
77 | b += sizeof(unsigned long); | |
78 | size -= sizeof(unsigned long); | |
79 | } | |
80 | #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ | |
81 | while (size > 0) { | |
82 | neq |= *(unsigned char *)a ^ *(unsigned char *)b; | |
fe8c8a12 | 83 | OPTIMIZER_HIDE_VAR(neq); |
6bf37e5a JY |
84 | a += 1; |
85 | b += 1; | |
86 | size -= 1; | |
87 | } | |
88 | return neq; | |
89 | } | |
90 | ||
91 | /* Loop-free fast-path for frequently used 16-byte size */ | |
92 | static inline unsigned long __crypto_memneq_16(const void *a, const void *b) | |
93 | { | |
fe8c8a12 CEB |
94 | unsigned long neq = 0; |
95 | ||
6bf37e5a | 96 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
fe8c8a12 CEB |
97 | if (sizeof(unsigned long) == 8) { |
98 | neq |= *(unsigned long *)(a) ^ *(unsigned long *)(b); | |
99 | OPTIMIZER_HIDE_VAR(neq); | |
100 | neq |= *(unsigned long *)(a+8) ^ *(unsigned long *)(b+8); | |
101 | OPTIMIZER_HIDE_VAR(neq); | |
102 | } else if (sizeof(unsigned int) == 4) { | |
103 | neq |= *(unsigned int *)(a) ^ *(unsigned int *)(b); | |
104 | OPTIMIZER_HIDE_VAR(neq); | |
105 | neq |= *(unsigned int *)(a+4) ^ *(unsigned int *)(b+4); | |
106 | OPTIMIZER_HIDE_VAR(neq); | |
107 | neq |= *(unsigned int *)(a+8) ^ *(unsigned int *)(b+8); | |
108 | OPTIMIZER_HIDE_VAR(neq); | |
109 | neq |= *(unsigned int *)(a+12) ^ *(unsigned int *)(b+12); | |
110 | OPTIMIZER_HIDE_VAR(neq); | |
e37b94eb | 111 | } else |
6bf37e5a | 112 | #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ |
e37b94eb | 113 | { |
fe8c8a12 CEB |
114 | neq |= *(unsigned char *)(a) ^ *(unsigned char *)(b); |
115 | OPTIMIZER_HIDE_VAR(neq); | |
116 | neq |= *(unsigned char *)(a+1) ^ *(unsigned char *)(b+1); | |
117 | OPTIMIZER_HIDE_VAR(neq); | |
118 | neq |= *(unsigned char *)(a+2) ^ *(unsigned char *)(b+2); | |
119 | OPTIMIZER_HIDE_VAR(neq); | |
120 | neq |= *(unsigned char *)(a+3) ^ *(unsigned char *)(b+3); | |
121 | OPTIMIZER_HIDE_VAR(neq); | |
122 | neq |= *(unsigned char *)(a+4) ^ *(unsigned char *)(b+4); | |
123 | OPTIMIZER_HIDE_VAR(neq); | |
124 | neq |= *(unsigned char *)(a+5) ^ *(unsigned char *)(b+5); | |
125 | OPTIMIZER_HIDE_VAR(neq); | |
126 | neq |= *(unsigned char *)(a+6) ^ *(unsigned char *)(b+6); | |
127 | OPTIMIZER_HIDE_VAR(neq); | |
128 | neq |= *(unsigned char *)(a+7) ^ *(unsigned char *)(b+7); | |
129 | OPTIMIZER_HIDE_VAR(neq); | |
130 | neq |= *(unsigned char *)(a+8) ^ *(unsigned char *)(b+8); | |
131 | OPTIMIZER_HIDE_VAR(neq); | |
132 | neq |= *(unsigned char *)(a+9) ^ *(unsigned char *)(b+9); | |
133 | OPTIMIZER_HIDE_VAR(neq); | |
134 | neq |= *(unsigned char *)(a+10) ^ *(unsigned char *)(b+10); | |
135 | OPTIMIZER_HIDE_VAR(neq); | |
136 | neq |= *(unsigned char *)(a+11) ^ *(unsigned char *)(b+11); | |
137 | OPTIMIZER_HIDE_VAR(neq); | |
138 | neq |= *(unsigned char *)(a+12) ^ *(unsigned char *)(b+12); | |
139 | OPTIMIZER_HIDE_VAR(neq); | |
140 | neq |= *(unsigned char *)(a+13) ^ *(unsigned char *)(b+13); | |
141 | OPTIMIZER_HIDE_VAR(neq); | |
142 | neq |= *(unsigned char *)(a+14) ^ *(unsigned char *)(b+14); | |
143 | OPTIMIZER_HIDE_VAR(neq); | |
144 | neq |= *(unsigned char *)(a+15) ^ *(unsigned char *)(b+15); | |
145 | OPTIMIZER_HIDE_VAR(neq); | |
146 | } | |
147 | ||
148 | return neq; | |
6bf37e5a JY |
149 | } |
150 | ||
151 | /* Compare two areas of memory without leaking timing information, | |
152 | * and with special optimizations for common sizes. Users should | |
153 | * not call this function directly, but should instead use | |
154 | * crypto_memneq defined in crypto/algapi.h. | |
155 | */ | |
156 | noinline unsigned long __crypto_memneq(const void *a, const void *b, | |
157 | size_t size) | |
158 | { | |
159 | switch (size) { | |
160 | case 16: | |
161 | return __crypto_memneq_16(a, b); | |
162 | default: | |
163 | return __crypto_memneq_generic(a, b, size); | |
164 | } | |
165 | } | |
166 | EXPORT_SYMBOL(__crypto_memneq); | |
167 | ||
168 | #endif /* __HAVE_ARCH_CRYPTO_MEMNEQ */ |