arm64/crypto: GHASH secure hash using ARMv8 Crypto Extensions

This is a port to ARMv8 (Crypto Extensions) of the Intel implementation of the
GHASH Secure Hash (used in the Galois/Counter chaining mode). It relies on the
optional PMULL/PMULL2 instruction (polynomial multiply long, what Intel call
carry-less multiply).
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/Kconfig

@@ -18,4 +18,10 @@ config CRYPTO_SHA2_ARM64_CE
 	depends on ARM64 && KERNEL_MODE_NEON
 	select CRYPTO_HASH
 
+
+config CRYPTO_GHASH_ARM64_CE
+	tristate "GHASH (for GCM chaining mode) using ARMv8 Crypto Extensions"
+	depends on ARM64 && KERNEL_MODE_NEON
+	select CRYPTO_HASH
+
 endif

arch/arm64/crypto/Makefile

@@ -13,3 +13,6 @@ sha1-ce-y := sha1-ce-glue.o sha1-ce-core.o
 
 obj-$(CONFIG_CRYPTO_SHA2_ARM64_CE) += sha2-ce.o
 sha2-ce-y := sha2-ce-glue.o sha2-ce-core.o
+
+obj-$(CONFIG_CRYPTO_GHASH_ARM64_CE) += ghash-ce.o
+ghash-ce-y := ghash-ce-glue.o ghash-ce-core.o

arch/arm64/crypto/ghash-ce-core.S

+/*
+ * Accelerated GHASH implementation with ARMv8 PMULL instructions.
+ *
+ * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * Based on arch/x86/crypto/ghash-pmullni-intel_asm.S
+ *
+ * Copyright (c) 2009 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ *           Vinodh Gopal
+ *           Erdinc Ozturk
+ *           Deniz Karakoyunlu
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+
+	DATA	.req	v0
+	SHASH	.req	v1
+	IN1	.req	v2
+	T1	.req	v2
+	T2	.req	v3
+	T3	.req	v4
+	VZR	.req	v5
+
+	.text
+	.arch		armv8-a+crypto
+
+	/*
+	 * void pmull_ghash_update(int blocks, u64 dg[], const char *src,
+	 *			   struct ghash_key const *k, const char *head)
+	 */
+ENTRY(pmull_ghash_update)
+	ld1		{DATA.16b}, [x1]
+	ld1		{SHASH.16b}, [x3]
+	eor		VZR.16b, VZR.16b, VZR.16b
+
+	/* do the head block first, if supplied */
+	cbz		x4, 0f
+	ld1		{IN1.2d}, [x4]
+	b		1f
+
+0:	ld1		{IN1.2d}, [x2], #16
+	sub		w0, w0, #1
+1:	ext		IN1.16b, IN1.16b, IN1.16b, #8
+CPU_LE(	rev64		IN1.16b, IN1.16b	)
+	eor		DATA.16b, DATA.16b, IN1.16b
+
+	/* multiply DATA by SHASH in GF(2^128) */
+	ext		T2.16b, DATA.16b, DATA.16b, #8
+	ext		T3.16b, SHASH.16b, SHASH.16b, #8
+	eor		T2.16b, T2.16b, DATA.16b
+	eor		T3.16b, T3.16b, SHASH.16b
+
+	pmull2		T1.1q, SHASH.2d, DATA.2d	// a1 * b1
+	pmull		DATA.1q, SHASH.1d, DATA.1d	// a0 * b0
+	pmull		T2.1q, T2.1d, T3.1d		// (a1 + a0)(b1 + b0)
+	eor		T2.16b, T2.16b, T1.16b		// (a0 * b1) + (a1 * b0)
+	eor		T2.16b, T2.16b, DATA.16b
+
+	ext		T3.16b, VZR.16b, T2.16b, #8
+	ext		T2.16b, T2.16b, VZR.16b, #8
+	eor		DATA.16b, DATA.16b, T3.16b
+	eor		T1.16b, T1.16b, T2.16b	// <T1:DATA> is result of
+						// carry-less multiplication
+
+	/* first phase of the reduction */
+	shl		T3.2d, DATA.2d, #1
+	eor		T3.16b, T3.16b, DATA.16b
+	shl		T3.2d, T3.2d, #5
+	eor		T3.16b, T3.16b, DATA.16b
+	shl		T3.2d, T3.2d, #57
+	ext		T2.16b, VZR.16b, T3.16b, #8
+	ext		T3.16b, T3.16b, VZR.16b, #8
+	eor		DATA.16b, DATA.16b, T2.16b
+	eor		T1.16b, T1.16b, T3.16b
+
+	/* second phase of the reduction */
+	ushr		T2.2d, DATA.2d, #5
+	eor		T2.16b, T2.16b, DATA.16b
+	ushr		T2.2d, T2.2d, #1
+	eor		T2.16b, T2.16b, DATA.16b
+	ushr		T2.2d, T2.2d, #1
+	eor		T1.16b, T1.16b, T2.16b
+	eor		DATA.16b, DATA.16b, T1.16b
+
+	cbnz		w0, 0b
+
+	st1		{DATA.16b}, [x1]
+	ret
+ENDPROC(pmull_ghash_update)

arch/arm64/crypto/ghash-ce-glue.c

+/*
+ * Accelerated GHASH implementation with ARMv8 PMULL instructions.
+ *
+ * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <asm/neon.h>
+#include <asm/unaligned.h>
+#include <crypto/internal/hash.h>
+#include <linux/cpufeature.h>
+#include <linux/crypto.h>
+#include <linux/module.h>
+
+MODULE_DESCRIPTION("GHASH secure hash using ARMv8 Crypto Extensions");
+MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
+MODULE_LICENSE("GPL v2");
+
+#define GHASH_BLOCK_SIZE	16
+#define GHASH_DIGEST_SIZE	16
+
+struct ghash_key {
+	u64 a;
+	u64 b;
+};
+
+struct ghash_desc_ctx {
+	u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
+	u8 buf[GHASH_BLOCK_SIZE];
+	u32 count;
+};
+
+asmlinkage void pmull_ghash_update(int blocks, u64 dg[], const char *src,
+				   struct ghash_key const *k, const char *head);
+
+static int ghash_init(struct shash_desc *desc)
+{
+	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	*ctx = (struct ghash_desc_ctx){};
+	return 0;
+}
+
+static int ghash_update(struct shash_desc *desc, const u8 *src,
+			unsigned int len)
+{
+	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
+	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
+
+	ctx->count += len;
+
+	if ((partial + len) >= GHASH_BLOCK_SIZE) {
+		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
+		int blocks;
+
+		if (partial) {
+			int p = GHASH_BLOCK_SIZE - partial;
+
+			memcpy(ctx->buf + partial, src, p);
+			src += p;
+			len -= p;
+		}
+
+		blocks = len / GHASH_BLOCK_SIZE;
+		len %= GHASH_BLOCK_SIZE;
+
+		kernel_neon_begin_partial(6);
+		pmull_ghash_update(blocks, ctx->digest, src, key,
+				   partial ? ctx->buf : NULL);
+		kernel_neon_end();
+		src += blocks * GHASH_BLOCK_SIZE;
+	}
+	if (len)
+		memcpy(ctx->buf + partial, src, len);
+	return 0;
+}
+
+static int ghash_final(struct shash_desc *desc, u8 *dst)
+{
+	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
+	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
+
+	if (partial) {
+		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
+
+		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
+
+		kernel_neon_begin_partial(6);
+		pmull_ghash_update(1, ctx->digest, ctx->buf, key, NULL);
+		kernel_neon_end();
+	}
+	put_unaligned_be64(ctx->digest[1], dst);
+	put_unaligned_be64(ctx->digest[0], dst + 8);
+
+	*ctx = (struct ghash_desc_ctx){};
+	return 0;
+}
+
+static int ghash_setkey(struct crypto_shash *tfm,
+			const u8 *inkey, unsigned int keylen)
+{
+	struct ghash_key *key = crypto_shash_ctx(tfm);
+	u64 a, b;
+
+	if (keylen != GHASH_BLOCK_SIZE) {
+		crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
+		return -EINVAL;
+	}
+
+	/* perform multiplication by 'x' in GF(2^128) */
+	b = get_unaligned_be64(inkey);
+	a = get_unaligned_be64(inkey + 8);
+
+	key->a = (a << 1) | (b >> 63);
+	key->b = (b << 1) | (a >> 63);
+
+	if (b >> 63)
+		key->b ^= 0xc200000000000000UL;
+
+	return 0;
+}
+
+static struct shash_alg ghash_alg = {
+	.digestsize	= GHASH_DIGEST_SIZE,
+	.init		= ghash_init,
+	.update		= ghash_update,
+	.final		= ghash_final,
+	.setkey		= ghash_setkey,
+	.descsize	= sizeof(struct ghash_desc_ctx),
+	.base		= {
+		.cra_name		= "ghash",
+		.cra_driver_name	= "ghash-ce",
+		.cra_priority		= 200,
+		.cra_flags		= CRYPTO_ALG_TYPE_SHASH,
+		.cra_blocksize		= GHASH_BLOCK_SIZE,
+		.cra_ctxsize		= sizeof(struct ghash_key),
+		.cra_module		= THIS_MODULE,
+	},
+};
+
+static int __init ghash_ce_mod_init(void)
+{
+	return crypto_register_shash(&ghash_alg);
+}
+
+static void __exit ghash_ce_mod_exit(void)
+{
+	crypto_unregister_shash(&ghash_alg);
+}
+
+module_cpu_feature_match(PMULL, ghash_ce_mod_init);
+module_exit(ghash_ce_mod_exit);