net: tls: Refactor control message handling on recv

For TLS 1.3, the control message is encrypted.  Handle control
message checks after decryption.
Signed-off-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tls/tls_sw.c

@@ -1421,15 +1421,14 @@ static int decrypt_skb_update(struct sock *sk, struct sk_buff *skb,
 
 			return err;
 		}
-	} else {
-		*zc = false;
-	}
-
 		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);
+	} else {
+		*zc = false;
+	}
 
 	return err;
 }
@@ -1609,6 +1608,25 @@ int tls_sw_recvmsg(struct sock *sk,
 
 		rxm = strp_msg(skb);
 
+		to_decrypt = rxm->full_len - tls_ctx->rx.overhead_size;
+
+		if (to_decrypt <= len && !is_kvec && !is_peek &&
+		    ctx->control == TLS_RECORD_TYPE_DATA)
+			zc = true;
+
+		err = decrypt_skb_update(sk, skb, &msg->msg_iter,
+					 &chunk, &zc, ctx->async_capable);
+		if (err < 0 && err != -EINPROGRESS) {
+			tls_err_abort(sk, EBADMSG);
+			goto recv_end;
+		}
+
+		if (err == -EINPROGRESS) {
+			async = true;
+			num_async++;
+			goto pick_next_record;
+		}
+
 		if (!cmsg) {
 			int cerr;
 
@@ -1626,23 +1644,6 @@ int tls_sw_recvmsg(struct sock *sk,
 			goto recv_end;
 		}
 
-		to_decrypt = rxm->full_len - tls_ctx->rx.overhead_size;
-
-		if (to_decrypt <= len && !is_kvec && !is_peek)
-			zc = true;
-
-		err = decrypt_skb_update(sk, skb, &msg->msg_iter,
-					 &chunk, &zc, ctx->async_capable);
-		if (err < 0 && err != -EINPROGRESS) {
-			tls_err_abort(sk, EBADMSG);
-			goto recv_end;
-		}
-
-		if (err == -EINPROGRESS) {
-			async = true;
-			num_async++;
-			goto pick_next_record;
-		} else {
 		if (!zc) {
 			if (rxm->full_len > len) {
 				retain_skb = true;
@@ -1661,7 +1662,6 @@ int tls_sw_recvmsg(struct sock *sk,
 				rxm->full_len = rxm->full_len - chunk;
 			}
 		}
-		}
 
 pick_next_record:
 		if (chunk > len)
@@ -1759,15 +1759,15 @@ ssize_t tls_sw_splice_read(struct socket *sock,  loff_t *ppos,
 	if (!skb)
 		goto splice_read_end;
 
+	if (!ctx->decrypted) {
+		err = decrypt_skb_update(sk, skb, NULL, &chunk, &zc, false);
+
 		/* splice does not support reading control messages */
 		if (ctx->control != TLS_RECORD_TYPE_DATA) {
 			err = -ENOTSUPP;
 			goto splice_read_end;
 		}
 
-	if (!ctx->decrypted) {
-		err = decrypt_skb_update(sk, skb, NULL, &chunk, &zc, false);
-
 		if (err < 0) {
 			tls_err_abort(sk, EBADMSG);
 			goto splice_read_end;