diff options
-rw-r--r-- | crypto/Makefile | 1 | ||||
-rw-r--r-- | crypto/memneq.c | 91 | ||||
-rw-r--r-- | include/crypto.h | 17 |
3 files changed, 109 insertions, 0 deletions
diff --git a/crypto/Makefile b/crypto/Makefile index 3f59de08f0..5da58d7998 100644 --- a/crypto/Makefile +++ b/crypto/Makefile @@ -12,6 +12,7 @@ pbl-$(CONFIG_PBL_VERIFY_PIGGY) += sha2.o pbl-$(CONFIG_PBL_VERIFY_PIGGY) += digest.o obj-$(CONFIG_DIGEST_SHA384_GENERIC) += sha4.o obj-$(CONFIG_DIGEST_SHA512_GENERIC) += sha4.o +obj-y += memneq.o obj-$(CONFIG_CRYPTO_PBKDF2) += pbkdf2.o obj-$(CONFIG_CRYPTO_RSA) += rsa.o diff --git a/crypto/memneq.c b/crypto/memneq.c new file mode 100644 index 0000000000..3bade0b7b7 --- /dev/null +++ b/crypto/memneq.c @@ -0,0 +1,91 @@ +/* + * 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 <common.h> +#include <crypto.h> + +/* 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) +{ + 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; +} diff --git a/include/crypto.h b/include/crypto.h index ac70111cab..4aca467de9 100644 --- a/include/crypto.h +++ b/include/crypto.h @@ -24,4 +24,21 @@ struct ablkcipher_request { void __iomem *src; }; +noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size); + +/** + * crypto_memneq - Compare two areas of memory without leaking + * timing information. + * + * @a: One area of memory + * @b: Another area of memory + * @size: The size of the area. + * + * Returns 0 when data is equal, 1 otherwise. + */ +static inline int crypto_memneq(const void *a, const void *b, size_t size) +{ + return __crypto_memneq(a, b, size) != 0UL ? 1 : 0; +} + #endif |