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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 [ # # ]: 0 : while (size >= sizeof(unsigned long)) {
74 : 0 : neq |= *(unsigned long *)a ^ *(unsigned long *)b;
75 : 0 : OPTIMIZER_HIDE_VAR(neq);
76 : 0 : a += sizeof(unsigned long);
77 : 0 : b += sizeof(unsigned long);
78 : 0 : size -= sizeof(unsigned long);
79 : : }
80 : : #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
81 [ # # ]: 0 : while (size > 0) {
82 : 0 : neq |= *(unsigned char *)a ^ *(unsigned char *)b;
83 : 0 : OPTIMIZER_HIDE_VAR(neq);
84 : 0 : a += 1;
85 : 0 : b += 1;
86 : 0 : 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 : : {
94 : : unsigned long neq = 0;
95 : :
96 : : #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
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 : 0 : neq |= *(unsigned int *)(a) ^ *(unsigned int *)(b);
104 : 0 : OPTIMIZER_HIDE_VAR(neq);
105 : 0 : neq |= *(unsigned int *)(a+4) ^ *(unsigned int *)(b+4);
106 : 0 : OPTIMIZER_HIDE_VAR(neq);
107 : 0 : neq |= *(unsigned int *)(a+8) ^ *(unsigned int *)(b+8);
108 : 0 : OPTIMIZER_HIDE_VAR(neq);
109 : 0 : neq |= *(unsigned int *)(a+12) ^ *(unsigned int *)(b+12);
110 : 0 : OPTIMIZER_HIDE_VAR(neq);
111 : : } else
112 : : #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
113 : : {
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;
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 : 0 : noinline unsigned long __crypto_memneq(const void *a, const void *b,
157 : : size_t size)
158 : : {
159 [ # # ]: 0 : switch (size) {
160 : : case 16:
161 : 0 : 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 */
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