crypto: drbg - use single block cipher API

The CTR DRBG only encrypts one single block at a time. Thus, use the
single block crypto API to avoid additional overhead from the block
chaining modes.

With the patch, the speed of the DRBG increases between 30% and 40%.

The DRBG still passes the CTR DRBG CAVS test.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 16 insertions, 23 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index d8ff16e5c322..c14274ac8d61 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -119,19 +119,19 @@ static const struct drbg_core drbg_cores[] = {
                 .statelen = 32, /* 256 bits as defined in 10.2.1 */
                 .blocklen_bytes = 16,
                 .cra_name = "ctr_aes128",
-                .backend_cra_name = "ecb(aes)",
+                .backend_cra_name = "aes",
         }, {
                 .flags = DRBG_CTR | DRBG_STRENGTH192,
                 .statelen = 40, /* 320 bits as defined in 10.2.1 */
                 .blocklen_bytes = 16,
                 .cra_name = "ctr_aes192",
-                .backend_cra_name = "ecb(aes)",
+                .backend_cra_name = "aes",
         }, {
                 .flags = DRBG_CTR | DRBG_STRENGTH256,
                 .statelen = 48, /* 384 bits as defined in 10.2.1 */
                 .blocklen_bytes = 16,
                 .cra_name = "ctr_aes256",
-                .backend_cra_name = "ecb(aes)",
+                .backend_cra_name = "aes",
         },
 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 #ifdef CONFIG_CRYPTO_DRBG_HASH
@@ -1644,24 +1644,24 @@ static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
 static int drbg_init_sym_kernel(struct drbg_state *drbg)
 {
         int ret = 0;
-        struct crypto_blkcipher *tfm;
+        struct crypto_cipher *tfm;
 
-        tfm = crypto_alloc_blkcipher(drbg->core->backend_cra_name, 0, 0);
+        tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
         if (IS_ERR(tfm)) {
                 pr_info("DRBG: could not allocate cipher TFM handle\n");
                 return PTR_ERR(tfm);
         }
-        BUG_ON(drbg_blocklen(drbg) != crypto_blkcipher_blocksize(tfm));
+        BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
         drbg->priv_data = tfm;
         return ret;
 }
 
 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
 {
-        struct crypto_blkcipher *tfm =
-                (struct crypto_blkcipher *)drbg->priv_data;
+        struct crypto_cipher *tfm =
+                (struct crypto_cipher *)drbg->priv_data;
         if (tfm)
-                crypto_free_blkcipher(tfm);
+                crypto_free_cipher(tfm);
         drbg->priv_data = NULL;
         return 0;
 }
@@ -1669,21 +1669,14 @@ static int drbg_fini_sym_kernel(struct drbg_state *drbg)
 static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
                           unsigned char *outval, const struct drbg_string *in)
 {
-        int ret = 0;
-        struct scatterlist sg_in, sg_out;
-        struct blkcipher_desc desc;
-        struct crypto_blkcipher *tfm =
-                (struct crypto_blkcipher *)drbg->priv_data;
-
-        desc.tfm = tfm;
-        desc.flags = 0;
-        crypto_blkcipher_setkey(tfm, key, (drbg_keylen(drbg)));
-        /* there is only component in *in */
-        sg_init_one(&sg_in, in->buf, in->len);
-        sg_init_one(&sg_out, outval, drbg_blocklen(drbg));
-        ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, in->len);
+        struct crypto_cipher *tfm =
+                (struct crypto_cipher *)drbg->priv_data;
 
-        return ret;
+        crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
+        /* there is only component in *in */
+        BUG_ON(in->len < drbg_blocklen(drbg));
+        crypto_cipher_encrypt_one(tfm, outval, in->buf);
+        return 0;
 }
 #endif /* CONFIG_CRYPTO_DRBG_CTR */