[PATCH 3/9] crypto: serpent - use unaligned accessors instead of alignmask

[Ard Biesheuvel <ardb@kernel.org>]

Instead of using an alignmask of 0x3 to ensure 32-bit alignment of the
Serpent input and output blocks, which propagates to mode drivers, and
results in pointless copying on architectures that don't care about
alignment, use the unaligned accessors, which will do the right thing on
each respective architecture, avoiding the need for double buffering.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 crypto/serpent_generic.c | 44 ++++++++------------
 1 file changed, 17 insertions(+), 27 deletions(-)

diff --git a/crypto/serpent_generic.c b/crypto/serpent_generic.c
index a932e0b2964f..236c87547a17 100644
--- a/crypto/serpent_generic.c
+++ b/crypto/serpent_generic.c
@@ -10,7 +10,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/errno.h>
-#include <asm/byteorder.h>
+#include <asm/unaligned.h>
 #include <linux/crypto.h>
 #include <linux/types.h>
 #include <crypto/serpent.h>
@@ -448,19 +448,12 @@ void __serpent_encrypt(const void *c, u8 *dst, const u8 *src)
 {
 	const struct serpent_ctx *ctx = c;
 	const u32 *k = ctx->expkey;
-	const __le32 *s = (const __le32 *)src;
-	__le32	*d = (__le32 *)dst;
 	u32	r0, r1, r2, r3, r4;
 
-/*
- * Note: The conversions between u8* and u32* might cause trouble
- * on architectures with stricter alignment rules than x86
- */
-
-	r0 = le32_to_cpu(s[0]);
-	r1 = le32_to_cpu(s[1]);
-	r2 = le32_to_cpu(s[2]);
-	r3 = le32_to_cpu(s[3]);
+	r0 = get_unaligned_le32(src);
+	r1 = get_unaligned_le32(src + 4);
+	r2 = get_unaligned_le32(src + 8);
+	r3 = get_unaligned_le32(src + 12);
 
 					K(r0, r1, r2, r3, 0);
 	S0(r0, r1, r2, r3, r4);		LK(r2, r1, r3, r0, r4, 1);
@@ -496,10 +489,10 @@ void __serpent_encrypt(const void *c, u8 *dst, const u8 *src)
 	S6(r0, r1, r3, r2, r4);		LK(r3, r4, r1, r2, r0, 31);
 	S7(r3, r4, r1, r2, r0);		K(r0, r1, r2, r3, 32);
 
-	d[0] = cpu_to_le32(r0);
-	d[1] = cpu_to_le32(r1);
-	d[2] = cpu_to_le32(r2);
-	d[3] = cpu_to_le32(r3);
+	put_unaligned_le32(r0, dst);
+	put_unaligned_le32(r1, dst + 4);
+	put_unaligned_le32(r2, dst + 8);
+	put_unaligned_le32(r3, dst + 12);
 }
 EXPORT_SYMBOL_GPL(__serpent_encrypt);
 
@@ -514,14 +507,12 @@ void __serpent_decrypt(const void *c, u8 *dst, const u8 *src)
 {
 	const struct serpent_ctx *ctx = c;
 	const u32 *k = ctx->expkey;
-	const __le32 *s = (const __le32 *)src;
-	__le32	*d = (__le32 *)dst;
 	u32	r0, r1, r2, r3, r4;
 
-	r0 = le32_to_cpu(s[0]);
-	r1 = le32_to_cpu(s[1]);
-	r2 = le32_to_cpu(s[2]);
-	r3 = le32_to_cpu(s[3]);
+	r0 = get_unaligned_le32(src);
+	r1 = get_unaligned_le32(src + 4);
+	r2 = get_unaligned_le32(src + 8);
+	r3 = get_unaligned_le32(src + 12);
 
 					K(r0, r1, r2, r3, 32);
 	SI7(r0, r1, r2, r3, r4);	KL(r1, r3, r0, r4, r2, 31);
@@ -557,10 +548,10 @@ void __serpent_decrypt(const void *c, u8 *dst, const u8 *src)
 	SI1(r3, r1, r2, r0, r4);	KL(r4, r1, r2, r0, r3, 1);
 	SI0(r4, r1, r2, r0, r3);	K(r2, r3, r1, r4, 0);
 
-	d[0] = cpu_to_le32(r2);
-	d[1] = cpu_to_le32(r3);
-	d[2] = cpu_to_le32(r1);
-	d[3] = cpu_to_le32(r4);
+	put_unaligned_le32(r2, dst);
+	put_unaligned_le32(r3, dst + 4);
+	put_unaligned_le32(r1, dst + 8);
+	put_unaligned_le32(r4, dst + 12);
 }
 EXPORT_SYMBOL_GPL(__serpent_decrypt);
 
@@ -578,7 +569,6 @@ static struct crypto_alg srp_alg = {
 	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
 	.cra_blocksize		=	SERPENT_BLOCK_SIZE,
 	.cra_ctxsize		=	sizeof(struct serpent_ctx),
-	.cra_alignmask		=	3,
 	.cra_module		=	THIS_MODULE,
 	.cra_u			=	{ .cipher = {
 	.cia_min_keysize	=	SERPENT_MIN_KEY_SIZE,
-- 
2.20.1