/* * Constant-time equality testing of memory regions. * * Authors: * * James Yonan * Daniel Borkmann * * 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 #ifndef __HAVE_ARCH_CRYPTO_MEMNEQ /* 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 |= *(unsigned long *)a ^ *(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 |= *(unsigned long *)(a) ^ *(unsigned long *)(b); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned long *)(a+8) ^ *(unsigned long *)(b+8); OPTIMIZER_HIDE_VAR(neq); } else if (sizeof(unsigned int) == 4) { neq |= *(unsigned int *)(a) ^ *(unsigned int *)(b); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned int *)(a+4) ^ *(unsigned int *)(b+4); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned int *)(a+8) ^ *(unsigned int *)(b+8); OPTIMIZER_HIDE_VAR(neq); neq |= *(unsigned int *)(a+12) ^ *(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); #endif /* __HAVE_ARCH_CRYPTO_MEMNEQ */