crypto: serpent-sse2 - add xts support

Patch adds XTS support for serpent-sse2 by using xts_crypt(). Patch has been
tested with tcrypt and automated filesystem tests.

Tcrypt benchmarks results (serpent-sse2/serpent_generic speed ratios):

Intel Celeron T1600 (x86_64) (fam:6, model:15, step:13):
size    xts-enc xts-dec
16B     0.98x   1.00x
64B     1.00x   1.01x
256B    2.78x   2.75x
1024B   3.30x   3.26x
8192B   3.39x   3.30x

AMD Phenom II 1055T (x86_64) (fam:16, model:10):
size    xts-enc xts-dec
16B     1.05x   1.02x
64B     1.04x   1.03x
256B    2.10x   2.05x
1024B   2.34x   2.35x
8192B   2.34x   2.40x

Intel Atom N270 (i586):
size    xts-enc xts-dec
16B     0.95x   0.96x
64B     1.53x   1.50x
256B    1.72x   1.75x
1024B   1.88x   1.87x
8192B   1.86x   1.83x

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 178 insertions, 2 deletions

diff --git a/arch/x86/crypto/serpent_sse2_glue.c b/arch/x86/crypto/serpent_sse2_glue.c
index db318e5cb240..2dffc5ab883e 100644
--- a/arch/x86/crypto/serpent_sse2_glue.c
+++ b/arch/x86/crypto/serpent_sse2_glue.c
@@ -40,6 +40,7 @@
 #include <crypto/b128ops.h>
 #include <crypto/ctr.h>
 #include <crypto/lrw.h>
+#include <crypto/xts.h>
 #include <asm/i387.h>
 #include <asm/serpent.h>
 #include <crypto/scatterwalk.h>
@@ -50,6 +51,10 @@
 #define HAS_LRW
 #endif
 
+#if defined(CONFIG_CRYPTO_XTS) || defined(CONFIG_CRYPTO_XTS_MODULE)
+#define HAS_XTS
+#endif
+
 struct async_serpent_ctx {
         struct cryptd_ablkcipher *cryptd_tfm;
 };
@@ -465,7 +470,7 @@ static struct crypto_alg blk_ctr_alg = {
         },
 };
 
-#ifdef HAS_LRW
+#if defined(HAS_LRW) || defined(HAS_XTS)
 
 struct crypt_priv {
         struct serpent_ctx *ctx;
@@ -506,6 +511,10 @@ static void decrypt_callback(void *priv, u8 *srcdst, unsigned int nbytes)
                 __serpent_decrypt(ctx->ctx, srcdst, srcdst);
 }
 
+#endif
+
+#ifdef HAS_LRW
+
 struct serpent_lrw_ctx {
         struct lrw_table_ctx lrw_table;
         struct serpent_ctx serpent_ctx;
@@ -611,6 +620,114 @@ static struct crypto_alg blk_lrw_alg = {
 
 #endif
 
+#ifdef HAS_XTS
+
+struct serpent_xts_ctx {
+        struct serpent_ctx tweak_ctx;
+        struct serpent_ctx crypt_ctx;
+};
+
+static int xts_serpent_setkey(struct crypto_tfm *tfm, const u8 *key,
+                              unsigned int keylen)
+{
+        struct serpent_xts_ctx *ctx = crypto_tfm_ctx(tfm);
+        u32 *flags = &tfm->crt_flags;
+        int err;
+
+        /* key consists of keys of equal size concatenated, therefore
+         * the length must be even
+         */
+        if (keylen % 2) {
+                *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
+                return -EINVAL;
+        }
+
+        /* first half of xts-key is for crypt */
+        err = __serpent_setkey(&ctx->crypt_ctx, key, keylen / 2);
+        if (err)
+                return err;
+
+        /* second half of xts-key is for tweak */
+        return __serpent_setkey(&ctx->tweak_ctx, key + keylen / 2, keylen / 2);
+}
+
+static int xts_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+                       struct scatterlist *src, unsigned int nbytes)
+{
+        struct serpent_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
+        be128 buf[SERPENT_PARALLEL_BLOCKS];
+        struct crypt_priv crypt_ctx = {
+                .ctx = &ctx->crypt_ctx,
+                .fpu_enabled = false,
+        };
+        struct xts_crypt_req req = {
+                .tbuf = buf,
+                .tbuflen = sizeof(buf),
+
+                .tweak_ctx = &ctx->tweak_ctx,
+                .tweak_fn = XTS_TWEAK_CAST(__serpent_encrypt),
+                .crypt_ctx = &crypt_ctx,
+                .crypt_fn = encrypt_callback,
+        };
+        int ret;
+
+        ret = xts_crypt(desc, dst, src, nbytes, &req);
+        serpent_fpu_end(crypt_ctx.fpu_enabled);
+
+        return ret;
+}
+
+static int xts_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+                       struct scatterlist *src, unsigned int nbytes)
+{
+        struct serpent_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
+        be128 buf[SERPENT_PARALLEL_BLOCKS];
+        struct crypt_priv crypt_ctx = {
+                .ctx = &ctx->crypt_ctx,
+                .fpu_enabled = false,
+        };
+        struct xts_crypt_req req = {
+                .tbuf = buf,
+                .tbuflen = sizeof(buf),
+
+                .tweak_ctx = &ctx->tweak_ctx,
+                .tweak_fn = XTS_TWEAK_CAST(__serpent_encrypt),
+                .crypt_ctx = &crypt_ctx,
+                .crypt_fn = decrypt_callback,
+        };
+        int ret;
+
+        ret = xts_crypt(desc, dst, src, nbytes, &req);
+        serpent_fpu_end(crypt_ctx.fpu_enabled);
+
+        return ret;
+}
+
+static struct crypto_alg blk_xts_alg = {
+        .cra_name               = "__xts-serpent-sse2",
+        .cra_driver_name        = "__driver-xts-serpent-sse2",
+        .cra_priority           = 0,
+        .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
+        .cra_blocksize          = SERPENT_BLOCK_SIZE,
+        .cra_ctxsize            = sizeof(struct serpent_xts_ctx),
+        .cra_alignmask          = 0,
+        .cra_type               = &crypto_blkcipher_type,
+        .cra_module             = THIS_MODULE,
+        .cra_list               = LIST_HEAD_INIT(blk_xts_alg.cra_list),
+        .cra_u = {
+                .blkcipher = {
+                        .min_keysize    = SERPENT_MIN_KEY_SIZE * 2,
+                        .max_keysize    = SERPENT_MAX_KEY_SIZE * 2,
+                        .ivsize         = SERPENT_BLOCK_SIZE,
+                        .setkey         = xts_serpent_setkey,
+                        .encrypt        = xts_encrypt,
+                        .decrypt        = xts_decrypt,
+                },
+        },
+};
+
+#endif
+
 static int ablk_set_key(struct crypto_ablkcipher *tfm, const u8 *key,
                         unsigned int key_len)
 {
@@ -851,6 +968,46 @@ static struct crypto_alg ablk_lrw_alg = {
 
 #endif
 
+#ifdef HAS_XTS
+
+static int ablk_xts_init(struct crypto_tfm *tfm)
+{
+        struct cryptd_ablkcipher *cryptd_tfm;
+
+        cryptd_tfm = cryptd_alloc_ablkcipher("__driver-xts-serpent-sse2", 0, 0);
+        if (IS_ERR(cryptd_tfm))
+                return PTR_ERR(cryptd_tfm);
+        ablk_init_common(tfm, cryptd_tfm);
+        return 0;
+}
+
+static struct crypto_alg ablk_xts_alg = {
+        .cra_name               = "xts(serpent)",
+        .cra_driver_name        = "xts-serpent-sse2",
+        .cra_priority           = 400,
+        .cra_flags              = CRYPTO_ALG_TYPE_ABLKCIPHER | CRYPTO_ALG_ASYNC,
+        .cra_blocksize          = SERPENT_BLOCK_SIZE,
+        .cra_ctxsize            = sizeof(struct async_serpent_ctx),
+        .cra_alignmask          = 0,
+        .cra_type               = &crypto_ablkcipher_type,
+        .cra_module             = THIS_MODULE,
+        .cra_list               = LIST_HEAD_INIT(ablk_xts_alg.cra_list),
+        .cra_init               = ablk_xts_init,
+        .cra_exit               = ablk_exit,
+        .cra_u = {
+                .ablkcipher = {
+                        .min_keysize    = SERPENT_MIN_KEY_SIZE * 2,
+                        .max_keysize    = SERPENT_MAX_KEY_SIZE * 2,
+                        .ivsize         = SERPENT_BLOCK_SIZE,
+                        .setkey         = ablk_set_key,
+                        .encrypt        = ablk_encrypt,
+                        .decrypt        = ablk_decrypt,
+                },
+        },
+};
+
+#endif
+
 static int __init serpent_sse2_init(void)
 {
         int err;
@@ -886,14 +1043,29 @@ static int __init serpent_sse2_init(void)
         if (err)
                 goto ablk_lrw_err;
 #endif
+#ifdef HAS_XTS
+        err = crypto_register_alg(&blk_xts_alg);
+        if (err)
+                goto blk_xts_err;
+        err = crypto_register_alg(&ablk_xts_alg);
+        if (err)
+                goto ablk_xts_err;
+#endif
         return err;
 
+#ifdef HAS_XTS
+        crypto_unregister_alg(&ablk_xts_alg);
+ablk_xts_err:
+        crypto_unregister_alg(&blk_xts_alg);
+blk_xts_err:
+#endif
 #ifdef HAS_LRW
+        crypto_unregister_alg(&ablk_lrw_alg);
 ablk_lrw_err:
         crypto_unregister_alg(&blk_lrw_alg);
 blk_lrw_err:
-        crypto_unregister_alg(&ablk_ctr_alg);
 #endif
+        crypto_unregister_alg(&ablk_ctr_alg);
 ablk_ctr_err:
         crypto_unregister_alg(&ablk_cbc_alg);
 ablk_cbc_err:
@@ -910,6 +1082,10 @@ blk_ecb_err:
 
 static void __exit serpent_sse2_exit(void)
 {
+#ifdef HAS_XTS
+        crypto_unregister_alg(&ablk_xts_alg);
+        crypto_unregister_alg(&blk_xts_alg);
+#endif
 #ifdef HAS_LRW
         crypto_unregister_alg(&ablk_lrw_alg);
         crypto_unregister_alg(&blk_lrw_alg);