crypto: vmx - Adding support for XTS

This patch add XTS support using VMX-crypto driver.
Signed-off-by: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/vmx/Makefile

 obj-$(CONFIG_CRYPTO_DEV_VMX_ENCRYPT) += vmx-crypto.o
-vmx-crypto-objs := vmx.o aesp8-ppc.o ghashp8-ppc.o aes.o aes_cbc.o aes_ctr.o ghash.o
+vmx-crypto-objs := vmx.o aesp8-ppc.o ghashp8-ppc.o aes.o aes_cbc.o aes_ctr.o aes_xts.o ghash.o
 
 ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
 TARGET := linux-ppc64le

drivers/crypto/vmx/aes_xts.c

+/**
+ * AES XTS routines supporting VMX In-core instructions on Power 8
+ *
+ * Copyright (C) 2015 International Business Machines Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundations; version 2 only.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY of FITNESS FOR A PARTICUPAR 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/err.h>
+#include <linux/crypto.h>
+#include <linux/delay.h>
+#include <linux/hardirq.h>
+#include <asm/switch_to.h>
+#include <crypto/aes.h>
+#include <crypto/scatterwalk.h>
+#include <crypto/xts.h>
+
+#include "aesp8-ppc.h"
+
+struct p8_aes_xts_ctx {
+	struct crypto_blkcipher *fallback;
+	struct aes_key enc_key;
+	struct aes_key dec_key;
+	struct aes_key tweak_key;
+};
+
+static int p8_aes_xts_init(struct crypto_tfm *tfm)
+{
+	const char *alg;
+	struct crypto_blkcipher *fallback;
+	struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	if (!(alg = crypto_tfm_alg_name(tfm))) {
+		printk(KERN_ERR "Failed to get algorithm name.\n");
+		return -ENOENT;
+	}
+
+	fallback =
+		crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
+	if (IS_ERR(fallback)) {
+		printk(KERN_ERR
+			"Failed to allocate transformation for '%s': %ld\n",
+			alg, PTR_ERR(fallback));
+		return PTR_ERR(fallback);
+	}
+	printk(KERN_INFO "Using '%s' as fallback implementation.\n",
+		crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
+
+	crypto_blkcipher_set_flags(
+		fallback,
+		crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
+	ctx->fallback = fallback;
+
+	return 0;
+}
+
+static void p8_aes_xts_exit(struct crypto_tfm *tfm)
+{
+	struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	if (ctx->fallback) {
+		crypto_free_blkcipher(ctx->fallback);
+		ctx->fallback = NULL;
+	}
+}
+
+static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key,
+			     unsigned int keylen)
+{
+	int ret;
+	struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	ret = xts_check_key(tfm, key, keylen);
+	if (ret)
+		return ret;
+
+	preempt_disable();
+	pagefault_disable();
+	enable_kernel_vsx();
+	ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
+	ret += aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
+	ret += aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
+	disable_kernel_vsx();
+	pagefault_enable();
+	preempt_enable();
+
+	ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
+	return ret;
+}
+
+static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
+			    struct scatterlist *dst,
+			    struct scatterlist *src,
+			    unsigned int nbytes, int enc)
+{
+	int ret;
+	u8 tweak[AES_BLOCK_SIZE];
+	u8 *iv;
+	struct blkcipher_walk walk;
+	struct p8_aes_xts_ctx *ctx =
+		crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
+	struct blkcipher_desc fallback_desc = {
+		.tfm = ctx->fallback,
+		.info = desc->info,
+		.flags = desc->flags
+	};
+
+	if (in_interrupt()) {
+		ret = enc ? crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes) :
+                            crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);
+	} else {
+		preempt_disable();
+		pagefault_disable();
+		enable_kernel_vsx();
+
+		blkcipher_walk_init(&walk, dst, src, nbytes);
+
+		iv = (u8 *)walk.iv;
+		ret = blkcipher_walk_virt(desc, &walk);
+		memset(tweak, 0, AES_BLOCK_SIZE);
+		aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
+
+		while ((nbytes = walk.nbytes)) {
+			if (enc)
+				aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
+						nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak);
+			else
+				aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
+						nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
+
+			nbytes &= AES_BLOCK_SIZE - 1;
+			ret = blkcipher_walk_done(desc, &walk, nbytes);
+		}
+
+		disable_kernel_vsx();
+		pagefault_enable();
+		preempt_enable();
+	}
+	return ret;
+}
+
+static int p8_aes_xts_encrypt(struct blkcipher_desc *desc,
+			      struct scatterlist *dst,
+			      struct scatterlist *src, unsigned int nbytes)
+{
+	return p8_aes_xts_crypt(desc, dst, src, nbytes, 1);
+}
+
+static int p8_aes_xts_decrypt(struct blkcipher_desc *desc,
+			      struct scatterlist *dst,
+			      struct scatterlist *src, unsigned int nbytes)
+{
+	return p8_aes_xts_crypt(desc, dst, src, nbytes, 0);
+}
+
+struct crypto_alg p8_aes_xts_alg = {
+	.cra_name = "xts(aes)",
+	.cra_driver_name = "p8_aes_xts",
+	.cra_module = THIS_MODULE,
+	.cra_priority = 2000,
+	.cra_type = &crypto_blkcipher_type,
+	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
+	.cra_alignmask = 0,
+	.cra_blocksize = AES_BLOCK_SIZE,
+	.cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
+	.cra_init = p8_aes_xts_init,
+	.cra_exit = p8_aes_xts_exit,
+	.cra_blkcipher = {
+			.ivsize = AES_BLOCK_SIZE,
+			.min_keysize = 2 * AES_MIN_KEY_SIZE,
+			.max_keysize = 2 * AES_MAX_KEY_SIZE,
+			.setkey	 = p8_aes_xts_setkey,
+			.encrypt = p8_aes_xts_encrypt,
+			.decrypt = p8_aes_xts_decrypt,
+	}
+};

drivers/crypto/vmx/vmx.c

@@ -31,10 +31,12 @@ extern struct shash_alg p8_ghash_alg;
 extern struct crypto_alg p8_aes_alg;
 extern struct crypto_alg p8_aes_cbc_alg;
 extern struct crypto_alg p8_aes_ctr_alg;
+extern struct crypto_alg p8_aes_xts_alg;
 static struct crypto_alg *algs[] = {
 	&p8_aes_alg,
 	&p8_aes_cbc_alg,
 	&p8_aes_ctr_alg,
+	&p8_aes_xts_alg,
 	NULL,
 };