[PATCH v3 25/32] crypto: ccp - move to AES library for CMAC key derivation

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

Use the AES library instead of the cipher interface to perform
the single block of AES processing involved in updating the key
of the cmac(aes) hash.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 drivers/crypto/ccp/Kconfig               |  1 +
 drivers/crypto/ccp/ccp-crypto-aes-cmac.c | 25 ++++----------------
 drivers/crypto/ccp/ccp-crypto.h          |  3 ---
 3 files changed, 5 insertions(+), 24 deletions(-)

diff --git a/drivers/crypto/ccp/Kconfig b/drivers/crypto/ccp/Kconfig
index b9dfae47aefd..ee06d0fccdb5 100644
--- a/drivers/crypto/ccp/Kconfig
+++ b/drivers/crypto/ccp/Kconfig
@@ -29,6 +29,7 @@ config CRYPTO_DEV_CCP_CRYPTO
 	select CRYPTO_BLKCIPHER
 	select CRYPTO_AUTHENC
 	select CRYPTO_RSA
+	select CRYPTO_LIB_AES
 	help
 	  Support for using the cryptographic API with the AMD Cryptographic
 	  Coprocessor. This module supports offload of SHA and AES algorithms.
diff --git a/drivers/crypto/ccp/ccp-crypto-aes-cmac.c b/drivers/crypto/ccp/ccp-crypto-aes-cmac.c
index f6e252c1d6fb..c8f4b29bf044 100644
--- a/drivers/crypto/ccp/ccp-crypto-aes-cmac.c
+++ b/drivers/crypto/ccp/ccp-crypto-aes-cmac.c
@@ -264,6 +264,7 @@ static int ccp_aes_cmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 		ccp_crypto_ahash_alg(crypto_ahash_tfm(tfm));
 	u64 k0_hi, k0_lo, k1_hi, k1_lo, k2_hi, k2_lo;
 	u64 rb_hi = 0x00, rb_lo = 0x87;
+	struct crypto_aes_ctx aes;
 	__be64 *gk;
 	int ret;
 
@@ -287,14 +288,14 @@ static int ccp_aes_cmac_setkey(struct crypto_ahash *tfm, const u8 *key,
 	ctx->u.aes.key_len = 0;
 
 	/* Set the key for the AES cipher used to generate the keys */
-	ret = crypto_cipher_setkey(ctx->u.aes.tfm_cipher, key, key_len);
+	ret = aes_expandkey(&aes, key, key_len);
 	if (ret)
 		return ret;
 
 	/* Encrypt a block of zeroes - use key area in context */
 	memset(ctx->u.aes.key, 0, sizeof(ctx->u.aes.key));
-	crypto_cipher_encrypt_one(ctx->u.aes.tfm_cipher, ctx->u.aes.key,
-				  ctx->u.aes.key);
+	aes_encrypt(&aes, ctx->u.aes.key, ctx->u.aes.key);
+	memzero_explicit(&aes, sizeof(aes));
 
 	/* Generate K1 and K2 */
 	k0_hi = be64_to_cpu(*((__be64 *)ctx->u.aes.key));
@@ -339,32 +340,15 @@ static int ccp_aes_cmac_cra_init(struct crypto_tfm *tfm)
 {
 	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct crypto_ahash *ahash = __crypto_ahash_cast(tfm);
-	struct crypto_cipher *cipher_tfm;
 
 	ctx->complete = ccp_aes_cmac_complete;
 	ctx->u.aes.key_len = 0;
 
 	crypto_ahash_set_reqsize(ahash, sizeof(struct ccp_aes_cmac_req_ctx));
 
-	cipher_tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_NEED_FALLBACK);
-	if (IS_ERR(cipher_tfm)) {
-		pr_warn("could not load aes cipher driver\n");
-		return PTR_ERR(cipher_tfm);
-	}
-	ctx->u.aes.tfm_cipher = cipher_tfm;
-
 	return 0;
 }
 
-static void ccp_aes_cmac_cra_exit(struct crypto_tfm *tfm)
-{
-	struct ccp_ctx *ctx = crypto_tfm_ctx(tfm);
-
-	if (ctx->u.aes.tfm_cipher)
-		crypto_free_cipher(ctx->u.aes.tfm_cipher);
-	ctx->u.aes.tfm_cipher = NULL;
-}
-
 int ccp_register_aes_cmac_algs(struct list_head *head)
 {
 	struct ccp_crypto_ahash_alg *ccp_alg;
@@ -404,7 +388,6 @@ int ccp_register_aes_cmac_algs(struct list_head *head)
 	base->cra_ctxsize = sizeof(struct ccp_ctx);
 	base->cra_priority = CCP_CRA_PRIORITY;
 	base->cra_init = ccp_aes_cmac_cra_init;
-	base->cra_exit = ccp_aes_cmac_cra_exit;
 	base->cra_module = THIS_MODULE;
 
 	ret = crypto_register_ahash(alg);
diff --git a/drivers/crypto/ccp/ccp-crypto.h b/drivers/crypto/ccp/ccp-crypto.h
index 28819e11db96..9100df77a7b3 100644
--- a/drivers/crypto/ccp/ccp-crypto.h
+++ b/drivers/crypto/ccp/ccp-crypto.h
@@ -90,9 +90,6 @@ struct ccp_aes_ctx {
 	/* Fallback cipher for XTS with unsupported unit sizes */
 	struct crypto_sync_skcipher *tfm_skcipher;
 
-	/* Cipher used to generate CMAC K1/K2 keys */
-	struct crypto_cipher *tfm_cipher;
-
 	enum ccp_engine engine;
 	enum ccp_aes_type type;
 	enum ccp_aes_mode mode;
-- 
2.20.1