tls: Split decrypt_skb to two functions

Previously, decrypt_skb also updated the TLS context.
Now, decrypt_skb only decrypts the payload using the current context,
while decrypt_skb_update also updates the state.

Later, in the tls_device Rx flow, we will use decrypt_skb directly.
Signed-off-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/tls.h

@@ -390,6 +390,8 @@ int tls_proccess_cmsg(struct sock *sk, struct msghdr *msg,
 		      unsigned char *record_type);
 void tls_register_device(struct tls_device *device);
 void tls_unregister_device(struct tls_device *device);
+int decrypt_skb(struct sock *sk, struct sk_buff *skb,
+		struct scatterlist *sgout);
 
 struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
 				      struct net_device *dev,

net/tls/tls_sw.c

@@ -53,7 +53,6 @@ static int tls_do_decryption(struct sock *sk,
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
-	struct strp_msg *rxm = strp_msg(skb);
 	struct aead_request *aead_req;
 
 	int ret;
@@ -71,18 +70,6 @@ static int tls_do_decryption(struct sock *sk,
 
 	ret = crypto_wait_req(crypto_aead_decrypt(aead_req), &ctx->async_wait);
 
-	if (ret < 0)
-		goto out;
-
-	rxm->offset += tls_ctx->rx.prepend_size;
-	rxm->full_len -= tls_ctx->rx.overhead_size;
-	tls_advance_record_sn(sk, &tls_ctx->rx);
-
-	ctx->decrypted = true;
-
-	ctx->saved_data_ready(sk);
-
-out:
 	aead_request_free(aead_req);
 	return ret;
 }
@@ -666,8 +653,29 @@ static struct sk_buff *tls_wait_data(struct sock *sk, int flags,
 	return skb;
 }
 
-static int decrypt_skb(struct sock *sk, struct sk_buff *skb,
-		       struct scatterlist *sgout)
+static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
+			      struct scatterlist *sgout)
+{
+	struct tls_context *tls_ctx = tls_get_ctx(sk);
+	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
+	struct strp_msg *rxm = strp_msg(skb);
+	int err = 0;
+
+	err = decrypt_skb(sk, skb, sgout);
+	if (err < 0)
+		return err;
+
+	rxm->offset += tls_ctx->rx.prepend_size;
+	rxm->full_len -= tls_ctx->rx.overhead_size;
+	tls_advance_record_sn(sk, &tls_ctx->rx);
+	ctx->decrypted = true;
+	ctx->saved_data_ready(sk);
+
+	return err;
+}
+
+int decrypt_skb(struct sock *sk, struct sk_buff *skb,
+		struct scatterlist *sgout)
 {
 	struct tls_context *tls_ctx = tls_get_ctx(sk);
 	struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
@@ -812,7 +820,7 @@ int tls_sw_recvmsg(struct sock *sk,
 				if (err < 0)
 					goto fallback_to_reg_recv;
 
-				err = decrypt_skb(sk, skb, sgin);
+				err = decrypt_skb_update(sk, skb, sgin);
 				for (; pages > 0; pages--)
 					put_page(sg_page(&sgin[pages]));
 				if (err < 0) {
@@ -821,7 +829,7 @@ int tls_sw_recvmsg(struct sock *sk,
 				}
 			} else {
 fallback_to_reg_recv:
-				err = decrypt_skb(sk, skb, NULL);
+				err = decrypt_skb_update(sk, skb, NULL);
 				if (err < 0) {
 					tls_err_abort(sk, EBADMSG);
 					goto recv_end;
@@ -892,7 +900,7 @@ ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	}
 
 	if (!ctx->decrypted) {
-		err = decrypt_skb(sk, skb, NULL);
+		err = decrypt_skb_update(sk, skb, NULL);
 
 		if (err < 0) {
 			tls_err_abort(sk, EBADMSG);