--- /dev/null
+/*
+ * 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 <crypto/algapi.h>
+
+#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 */
Code Review / kvmfornfv.git / blobdiff