net/tls: Use aead_request_alloc/free for request alloc/free

Instead of kzalloc/free for aead_request allocation and free, use
functions aead_request_alloc(), aead_request_free(). It ensures that
any sensitive crypto material held in crypto transforms is securely
erased from memory.
Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tls/tls_sw.c

@@ -57,14 +57,11 @@ static int tls_do_decryption(struct sock *sk,
 	struct aead_request *aead_req;
 
 	int ret;
-	unsigned int req_size = sizeof(struct aead_request) +
-		crypto_aead_reqsize(ctx->aead_recv);
 
-	aead_req = kzalloc(req_size, flags);
+	aead_req = aead_request_alloc(ctx->aead_recv, flags);
 	if (!aead_req)
 		return -ENOMEM;
 
-	aead_request_set_tfm(aead_req, ctx->aead_recv);
 	aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
 	aead_request_set_crypt(aead_req, sgin, sgout,
 			       data_len + tls_ctx->rx.tag_size,
@@ -86,7 +83,7 @@ static int tls_do_decryption(struct sock *sk,
 	ctx->saved_data_ready(sk);
 
 out:
-	kfree(aead_req);
+	aead_request_free(aead_req);
 	return ret;
 }
 
@@ -224,8 +221,7 @@ static int tls_push_record(struct sock *sk, int flags,
 	struct aead_request *req;
 	int rc;
 
-	req = kzalloc(sizeof(struct aead_request) +
-		      crypto_aead_reqsize(ctx->aead_send), sk->sk_allocation);
+	req = aead_request_alloc(ctx->aead_send, sk->sk_allocation);
 	if (!req)
 		return -ENOMEM;
 
@@ -267,7 +263,7 @@ static int tls_push_record(struct sock *sk, int flags,
 
 	tls_advance_record_sn(sk, &tls_ctx->tx);
 out_req:
-	kfree(req);
+	aead_request_free(req);
 	return rc;
 }