mptcp: use sha256() instead of open coding

Now that there's a function that calculates the SHA-256 digest of a
buffer in one step, use it instead of sha256_init() + sha256_update() +
sha256_final().
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Cc: mptcp@lists.01.org
Cc: Mat Martineau <mathew.j.martineau@linux.intel.com>
Cc: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

net/mptcp/crypto.c

@@ -32,11 +32,8 @@ void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
 {
 	__be32 mptcp_hashed_key[SHA256_DIGEST_WORDS];
 	__be64 input = cpu_to_be64(key);
-	struct sha256_state state;
 
-	sha256_init(&state);
-	sha256_update(&state, (__force u8 *)&input, sizeof(input));
-	sha256_final(&state, (u8 *)mptcp_hashed_key);
+	sha256((__force u8 *)&input, sizeof(input), (u8 *)mptcp_hashed_key);
 
 	if (token)
 		*token = be32_to_cpu(mptcp_hashed_key[0]);
@@ -47,7 +44,6 @@ void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
 {
 	u8 input[SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE];
-	struct sha256_state state;
 	u8 key1be[8];
 	u8 key2be[8];
 	int i;
@@ -67,13 +63,10 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
 
 	memcpy(&input[SHA256_BLOCK_SIZE], msg, len);
 
-	sha256_init(&state);
-	sha256_update(&state, input, SHA256_BLOCK_SIZE + len);
-
 	/* emit sha256(K1 || msg) on the second input block, so we can
 	 * reuse 'input' for the last hashing
 	 */
-	sha256_final(&state, &input[SHA256_BLOCK_SIZE]);
+	sha256(input, SHA256_BLOCK_SIZE + len, &input[SHA256_BLOCK_SIZE]);
 
 	/* Prepare second part of hmac */
 	memset(input, 0x5C, SHA256_BLOCK_SIZE);
@@ -82,9 +75,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
 	for (i = 0; i < 8; i++)
 		input[i + 8] ^= key2be[i];
 
-	sha256_init(&state);
-	sha256_update(&state, input, SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE);
-	sha256_final(&state, (u8 *)hmac);
+	sha256(input, SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE, hmac);
 }
 
 #ifdef CONFIG_MPTCP_HMAC_TEST