[PATCH v4 24/32] crypto: amcc/aes - switch to AES library for GCM key derivation

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

The AMCC code for GCM key derivation allocates a AES cipher to
perform a single block encryption. So let's switch to the new
and more lightweight AES library instead.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/crypto/Kconfig              |  2 +-
 drivers/crypto/amcc/crypto4xx_alg.c | 24 +++++++-------------
 2 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index b30b84089d11..c7ac1e6d23d4 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -311,7 +311,7 @@ config CRYPTO_DEV_PPC4XX
 	depends on PPC && 4xx
 	select CRYPTO_HASH
 	select CRYPTO_AEAD
-	select CRYPTO_AES
+	select CRYPTO_LIB_AES
 	select CRYPTO_CCM
 	select CRYPTO_CTR
 	select CRYPTO_GCM
diff --git a/drivers/crypto/amcc/crypto4xx_alg.c b/drivers/crypto/amcc/crypto4xx_alg.c
index 26f86fd7532b..d3660703a36c 100644
--- a/drivers/crypto/amcc/crypto4xx_alg.c
+++ b/drivers/crypto/amcc/crypto4xx_alg.c
@@ -536,28 +536,20 @@ static int crypto4xx_aes_gcm_validate_keylen(unsigned int keylen)
 static int crypto4xx_compute_gcm_hash_key_sw(__le32 *hash_start, const u8 *key,
 					     unsigned int keylen)
 {
-	struct crypto_cipher *aes_tfm = NULL;
+	struct crypto_aes_ctx ctx;
 	uint8_t src[16] = { 0 };
-	int rc = 0;
-
-	aes_tfm = crypto_alloc_cipher("aes", 0, CRYPTO_ALG_NEED_FALLBACK);
-	if (IS_ERR(aes_tfm)) {
-		rc = PTR_ERR(aes_tfm);
-		pr_warn("could not load aes cipher driver: %d\n", rc);
-		return rc;
-	}
+	int rc;
 
-	rc = crypto_cipher_setkey(aes_tfm, key, keylen);
+	rc = aes_expandkey(&ctx, key, keylen);
 	if (rc) {
-		pr_err("setkey() failed: %d\n", rc);
-		goto out;
+		pr_err("aes_expandkey() failed: %d\n", rc);
+		return rc;
 	}
 
-	crypto_cipher_encrypt_one(aes_tfm, src, src);
+	aes_encrypt(&ctx, src, src);
 	crypto4xx_memcpy_to_le32(hash_start, src, 16);
-out:
-	crypto_free_cipher(aes_tfm);
-	return rc;
+	memzero_explicit(&ctx, sizeof(ctx));
+	return 0;
 }
 
 int crypto4xx_setkey_aes_gcm(struct crypto_aead *cipher,
-- 
2.17.1