crypto: arm64/polyval - Add PMULL accelerated implementation of POLYVAL

Add hardware accelerated version of POLYVAL for ARM64 CPUs with
Crypto Extensions support.

This implementation is accelerated using PMULL instructions to perform
the finite field computations.  For added efficiency, 8 blocks of the
message are processed simultaneously by precomputing the first 8
powers of the key.

Karatsuba multiplication is used instead of Schoolbook multiplication
because it was found to be slightly faster on ARM64 CPUs.  Montgomery
reduction must be used instead of Barrett reduction due to the
difference in modulus between POLYVAL's field and other finite fields.

More information on POLYVAL can be found in the HCTR2 paper:
"Length-preserving encryption with HCTR2":
https://eprint.iacr.org/2021/1441.pdfSigned-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/Kconfig

@@ -72,6 +72,11 @@ config CRYPTO_GHASH_ARM64_CE
 	select CRYPTO_GF128MUL
 	select CRYPTO_LIB_AES
 
+config CRYPTO_POLYVAL_ARM64_CE
+	tristate "POLYVAL using ARMv8 Crypto Extensions (for HCTR2)"
+	depends on KERNEL_MODE_NEON
+	select CRYPTO_POLYVAL
+
 config CRYPTO_CRCT10DIF_ARM64_CE
 	tristate "CRCT10DIF digest algorithm using PMULL instructions"
 	depends on KERNEL_MODE_NEON && CRC_T10DIF

arch/arm64/crypto/Makefile

@@ -32,6 +32,9 @@ sm4-neon-y := sm4-neon-glue.o sm4-neon-core.o
 obj-$(CONFIG_CRYPTO_GHASH_ARM64_CE) += ghash-ce.o
 ghash-ce-y := ghash-ce-glue.o ghash-ce-core.o
 
+obj-$(CONFIG_CRYPTO_POLYVAL_ARM64_CE) += polyval-ce.o
+polyval-ce-y := polyval-ce-glue.o polyval-ce-core.o
+
 obj-$(CONFIG_CRYPTO_CRCT10DIF_ARM64_CE) += crct10dif-ce.o
 crct10dif-ce-y := crct10dif-ce-core.o crct10dif-ce-glue.o
 

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

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Glue code for POLYVAL using ARMv8 Crypto Extensions
+ *
+ * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
+ * Copyright (c) 2009 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ * Copyright 2021 Google LLC
+ */
+
+/*
+ * Glue code based on ghash-clmulni-intel_glue.c.
+ *
+ * This implementation of POLYVAL uses montgomery multiplication accelerated by
+ * ARMv8 Crypto Extensions instructions to implement the finite field operations.
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/internal/hash.h>
+#include <crypto/internal/simd.h>
+#include <crypto/polyval.h>
+#include <linux/crypto.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cpufeature.h>
+#include <asm/neon.h>
+#include <asm/simd.h>
+
+#define NUM_KEY_POWERS	8
+
+struct polyval_tfm_ctx {
+	/*
+	 * These powers must be in the order h^8, ..., h^1.
+	 */
+	u8 key_powers[NUM_KEY_POWERS][POLYVAL_BLOCK_SIZE];
+};
+
+struct polyval_desc_ctx {
+	u8 buffer[POLYVAL_BLOCK_SIZE];
+	u32 bytes;
+};
+
+asmlinkage void pmull_polyval_update(const struct polyval_tfm_ctx *keys,
+	const u8 *in, size_t nblocks, u8 *accumulator);
+asmlinkage void pmull_polyval_mul(u8 *op1, const u8 *op2);
+
+static void internal_polyval_update(const struct polyval_tfm_ctx *keys,
+	const u8 *in, size_t nblocks, u8 *accumulator)
+{
+	if (likely(crypto_simd_usable())) {
+		kernel_neon_begin();
+		pmull_polyval_update(keys, in, nblocks, accumulator);
+		kernel_neon_end();
+	} else {
+		polyval_update_non4k(keys->key_powers[NUM_KEY_POWERS-1], in,
+			nblocks, accumulator);
+	}
+}
+
+static void internal_polyval_mul(u8 *op1, const u8 *op2)
+{
+	if (likely(crypto_simd_usable())) {
+		kernel_neon_begin();
+		pmull_polyval_mul(op1, op2);
+		kernel_neon_end();
+	} else {
+		polyval_mul_non4k(op1, op2);
+	}
+}
+
+static int polyval_arm64_setkey(struct crypto_shash *tfm,
+			const u8 *key, unsigned int keylen)
+{
+	struct polyval_tfm_ctx *tctx = crypto_shash_ctx(tfm);
+	int i;
+
+	if (keylen != POLYVAL_BLOCK_SIZE)
+		return -EINVAL;
+
+	memcpy(tctx->key_powers[NUM_KEY_POWERS-1], key, POLYVAL_BLOCK_SIZE);
+
+	for (i = NUM_KEY_POWERS-2; i >= 0; i--) {
+		memcpy(tctx->key_powers[i], key, POLYVAL_BLOCK_SIZE);
+		internal_polyval_mul(tctx->key_powers[i],
+				     tctx->key_powers[i+1]);
+	}
+
+	return 0;
+}
+
+static int polyval_arm64_init(struct shash_desc *desc)
+{
+	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+
+	memset(dctx, 0, sizeof(*dctx));
+
+	return 0;
+}
+
+static int polyval_arm64_update(struct shash_desc *desc,
+			 const u8 *src, unsigned int srclen)
+{
+	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+	const struct polyval_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+	u8 *pos;
+	unsigned int nblocks;
+	unsigned int n;
+
+	if (dctx->bytes) {
+		n = min(srclen, dctx->bytes);
+		pos = dctx->buffer + POLYVAL_BLOCK_SIZE - dctx->bytes;
+
+		dctx->bytes -= n;
+		srclen -= n;
+
+		while (n--)
+			*pos++ ^= *src++;
+
+		if (!dctx->bytes)
+			internal_polyval_mul(dctx->buffer,
+					    tctx->key_powers[NUM_KEY_POWERS-1]);
+	}
+
+	while (srclen >= POLYVAL_BLOCK_SIZE) {
+		/* allow rescheduling every 4K bytes */
+		nblocks = min(srclen, 4096U) / POLYVAL_BLOCK_SIZE;
+		internal_polyval_update(tctx, src, nblocks, dctx->buffer);
+		srclen -= nblocks * POLYVAL_BLOCK_SIZE;
+		src += nblocks * POLYVAL_BLOCK_SIZE;
+	}
+
+	if (srclen) {
+		dctx->bytes = POLYVAL_BLOCK_SIZE - srclen;
+		pos = dctx->buffer;
+		while (srclen--)
+			*pos++ ^= *src++;
+	}
+
+	return 0;
+}
+
+static int polyval_arm64_final(struct shash_desc *desc, u8 *dst)
+{
+	struct polyval_desc_ctx *dctx = shash_desc_ctx(desc);
+	const struct polyval_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
+
+	if (dctx->bytes) {
+		internal_polyval_mul(dctx->buffer,
+				     tctx->key_powers[NUM_KEY_POWERS-1]);
+	}
+
+	memcpy(dst, dctx->buffer, POLYVAL_BLOCK_SIZE);
+
+	return 0;
+}
+
+static struct shash_alg polyval_alg = {
+	.digestsize	= POLYVAL_DIGEST_SIZE,
+	.init		= polyval_arm64_init,
+	.update		= polyval_arm64_update,
+	.final		= polyval_arm64_final,
+	.setkey		= polyval_arm64_setkey,
+	.descsize	= sizeof(struct polyval_desc_ctx),
+	.base		= {
+		.cra_name		= "polyval",
+		.cra_driver_name	= "polyval-ce",
+		.cra_priority		= 200,
+		.cra_blocksize		= POLYVAL_BLOCK_SIZE,
+		.cra_ctxsize		= sizeof(struct polyval_tfm_ctx),
+		.cra_module		= THIS_MODULE,
+	},
+};
+
+static int __init polyval_ce_mod_init(void)
+{
+	return crypto_register_shash(&polyval_alg);
+}
+
+static void __exit polyval_ce_mod_exit(void)
+{
+	crypto_unregister_shash(&polyval_alg);
+}
+
+module_cpu_feature_match(PMULL, polyval_ce_mod_init)
+module_exit(polyval_ce_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("POLYVAL hash function accelerated by ARMv8 Crypto Extensions");
+MODULE_ALIAS_CRYPTO("polyval");
+MODULE_ALIAS_CRYPTO("polyval-ce");