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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 | /* * Constant-time equality testing of memory regions. * * Authors: * * James Yonan <james@openvpn.net> * Daniel Borkmann <dborkman@redhat.com> * * This file is provided under a dual BSD/GPLv2 license. When using or * redistributing this file, you may do so under either license. * * GPL LICENSE SUMMARY * * Copyright(c) 2013 OpenVPN Technologies, Inc. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of version 2 of the GNU General Public License as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. * The full GNU General Public License is included in this distribution * in the file called LICENSE.GPL. * * BSD LICENSE * * Copyright(c) 2013 OpenVPN Technologies, Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * Neither the name of OpenVPN Technologies nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <asm/unaligned.h> #include <crypto/algapi.h> #include <linux/module.h> /* Generic path for arbitrary size */ static inline unsigned long __crypto_memneq_generic(const void *a, const void *b, size_t size) { unsigned long neq = 0; #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) while (size >= sizeof(unsigned long)) { neq |= get_unaligned((unsigned long *)a) ^ get_unaligned((unsigned long *)b); OPTIMIZER_HIDE_VAR(neq); a += sizeof(unsigned long); b += sizeof(unsigned long); size -= sizeof(unsigned long); } #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ while (size > 0) { neq |= *(unsigned char *)a ^ *(unsigned char *)b; OPTIMIZER_HIDE_VAR(neq); a += 1; b += 1; size -= 1; } return neq; } /* Loop-free fast-path for frequently used 16-byte size */ static inline unsigned long __crypto_memneq_16(const void *a, const void *b) { unsigned long neq = 0; #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS if (sizeof(unsigned long) == 8) { neq |= get_unaligned((unsigned long *)a) ^ get_unaligned((unsigned long *)b); OPTIMIZER_HIDE_VAR(neq); neq |= get_unaligned((unsigned long *)(a + 8)) ^ get_unaligned((unsigned long *)(b + 8)); OPTIMIZER_HIDE_VAR(neq); } else if (sizeof(unsigned int) == 4) { neq |= get_unaligned((unsigned int *)a) ^ get_unaligned((unsigned int *)b); OPTIMIZER_HIDE_VAR(neq); neq |= get_unaligned((unsigned int *)(a + 4)) ^ get_unaligned((unsigned int *)(b + 4)); OPTIMIZER_HIDE_VAR(neq); neq |= get_unaligned((unsigned int *)(a + 8)) ^ get_unaligned((unsigned int *)(b + 8)); OPTIMIZER_HIDE_VAR(neq); neq |= get_unaligned((unsigned int *)(a + 12)) ^ get_unaligned((unsigned int *)(b + 12)); OPTIMIZER_HIDE_VAR(neq); } else #endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */ { neq |= *(unsigned char *)(a) ^ *(unsigned char *)(b); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+1) ^ *(unsigned char *)(b+1); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+2) ^ *(unsigned char *)(b+2); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+3) ^ *(unsigned char *)(b+3); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+4) ^ *(unsigned char *)(b+4); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+5) ^ *(unsigned char *)(b+5); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+6) ^ *(unsigned char *)(b+6); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+7) ^ *(unsigned char *)(b+7); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+8) ^ *(unsigned char *)(b+8); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+9) ^ *(unsigned char *)(b+9); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+10) ^ *(unsigned char *)(b+10); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+11) ^ *(unsigned char *)(b+11); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+12) ^ *(unsigned char *)(b+12); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+13) ^ *(unsigned char *)(b+13); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+14) ^ *(unsigned char *)(b+14); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned char *)(a+15) ^ *(unsigned char *)(b+15); OPTIMIZER_HIDE_VAR(neq); } return neq; } /* Compare two areas of memory without leaking timing information, * and with special optimizations for common sizes. Users should * not call this function directly, but should instead use * crypto_memneq defined in crypto/algapi.h. */ noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size) { switch (size) { case 16: return __crypto_memneq_16(a, b); default: return __crypto_memneq_generic(a, b, size); } } EXPORT_SYMBOL(__crypto_memneq); |