[PATCH] crypto: x86/aes-ni - use AES library instead of single-use AES cipher

* [PATCH] crypto: x86/aes-ni - use AES library instead of single-use AES cipher
@ 2019-09-04 17:56 Ard Biesheuvel
  2019-09-09  7:54 ` Herbert Xu
  0 siblings, 1 reply; 2+ messages in thread
From: Ard Biesheuvel @ 2019-09-04 17:56 UTC (permalink / raw)
  To: linux-crypto; +Cc: herbert, Ard Biesheuvel

The RFC4106 key derivation code instantiates an AES cipher transform
to encrypt only a single block before it is freed again. Switch to
the new AES library which is more suitable for such use cases.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/x86/crypto/aesni-intel_glue.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index bf12bb71cecc..3e707e81afdb 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -628,26 +628,21 @@ static int xts_decrypt(struct skcipher_request *req)
 static int
 rfc4106_set_hash_subkey(u8 *hash_subkey, const u8 *key, unsigned int key_len)
 {
-	struct crypto_cipher *tfm;
+	struct crypto_aes_ctx ctx;
 	int ret;
 
-	tfm = crypto_alloc_cipher("aes", 0, 0);
-	if (IS_ERR(tfm))
-		return PTR_ERR(tfm);
-
-	ret = crypto_cipher_setkey(tfm, key, key_len);
+	ret = aes_expandkey(&ctx, key, key_len);
 	if (ret)
-		goto out_free_cipher;
+		return ret;
 
 	/* Clear the data in the hash sub key container to zero.*/
 	/* We want to cipher all zeros to create the hash sub key. */
 	memset(hash_subkey, 0, RFC4106_HASH_SUBKEY_SIZE);
 
-	crypto_cipher_encrypt_one(tfm, hash_subkey, hash_subkey);
+	aes_encrypt(&ctx, hash_subkey, hash_subkey);
 
-out_free_cipher:
-	crypto_free_cipher(tfm);
-	return ret;
+	memzero_explicit(&ctx, sizeof(ctx));
+	return 0;
 }
 
 static int common_rfc4106_set_key(struct crypto_aead *aead, const u8 *key,
-- 
2.17.1


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