[RFC PATCH v6 13/22] virtio/vsock: add SEQPACKET receive logic

[Arseny Krasnov <arseny.krasnov@kaspersky.com>]

This modifies current receive logic for SEQPACKET support:
1) Inserts 'SEQ_BEGIN' packet to socket's rx queue.
2) Inserts 'RW' packet to socket's rx queue, but without merging with
   buffer of last packet in queue.
3) Performs check for packet and socket types on receive(if mismatch,
   then reset connection).

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 net/vmw_vsock/virtio_transport_common.c | 63 +++++++++++++++++--------
 1 file changed, 44 insertions(+), 19 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 6fc78fec41c0..9d86375935ce 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -165,6 +165,14 @@ void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
 }
 EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);
 
+static u16 virtio_transport_get_type(struct sock *sk)
+{
+	if (sk->sk_type == SOCK_STREAM)
+		return VIRTIO_VSOCK_TYPE_STREAM;
+	else
+		return VIRTIO_VSOCK_TYPE_SEQPACKET;
+}
+
 /* This function can only be used on connecting/connected sockets,
  * since a socket assigned to a transport is required.
  *
@@ -1062,25 +1070,27 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
 		goto out;
 	}
 
-	/* Try to copy small packets into the buffer of last packet queued,
-	 * to avoid wasting memory queueing the entire buffer with a small
-	 * payload.
-	 */
-	if (pkt->len <= GOOD_COPY_LEN && !list_empty(&vvs->rx_queue)) {
-		struct virtio_vsock_pkt *last_pkt;
+	if (le16_to_cpu(pkt->hdr.type) == VIRTIO_VSOCK_TYPE_STREAM) {
+		/* Try to copy small packets into the buffer of last packet queued,
+		 * to avoid wasting memory queueing the entire buffer with a small
+		 * payload.
+		 */
+		if (pkt->len <= GOOD_COPY_LEN && !list_empty(&vvs->rx_queue)) {
+			struct virtio_vsock_pkt *last_pkt;
 
-		last_pkt = list_last_entry(&vvs->rx_queue,
-					   struct virtio_vsock_pkt, list);
+			last_pkt = list_last_entry(&vvs->rx_queue,
+						   struct virtio_vsock_pkt, list);
 
-		/* If there is space in the last packet queued, we copy the
-		 * new packet in its buffer.
-		 */
-		if (pkt->len <= last_pkt->buf_len - last_pkt->len) {
-			memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
-			       pkt->len);
-			last_pkt->len += pkt->len;
-			free_pkt = true;
-			goto out;
+			/* If there is space in the last packet queued, we copy the
+			 * new packet in its buffer.
+			 */
+			if (pkt->len <= last_pkt->buf_len - last_pkt->len) {
+				memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
+				       pkt->len);
+				last_pkt->len += pkt->len;
+				free_pkt = true;
+				goto out;
+			}
 		}
 	}
 
@@ -1100,9 +1110,13 @@ virtio_transport_recv_connected(struct sock *sk,
 	int err = 0;
 
 	switch (le16_to_cpu(pkt->hdr.op)) {
+	case VIRTIO_VSOCK_OP_SEQ_BEGIN:
+	case VIRTIO_VSOCK_OP_SEQ_END:
 	case VIRTIO_VSOCK_OP_RW:
 		virtio_transport_recv_enqueue(vsk, pkt);
-		sk->sk_data_ready(sk);
+
+		if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_SEQ_BEGIN)
+			sk->sk_data_ready(sk);
 		return err;
 	case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
 		sk->sk_write_space(sk);
@@ -1245,6 +1259,12 @@ virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
 	return 0;
 }
 
+static bool virtio_transport_valid_type(u16 type)
+{
+	return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
+	       (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
+}
+
 /* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
  * lock.
  */
@@ -1270,7 +1290,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
 					le32_to_cpu(pkt->hdr.buf_alloc),
 					le32_to_cpu(pkt->hdr.fwd_cnt));
 
-	if (le16_to_cpu(pkt->hdr.type) != VIRTIO_VSOCK_TYPE_STREAM) {
+	if (!virtio_transport_valid_type(le16_to_cpu(pkt->hdr.type))) {
 		(void)virtio_transport_reset_no_sock(t, pkt);
 		goto free_pkt;
 	}
@@ -1287,6 +1307,11 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,
 		}
 	}
 
+	if (virtio_transport_get_type(sk) != le16_to_cpu(pkt->hdr.type)) {
+		(void)virtio_transport_reset_no_sock(t, pkt);
+		goto free_pkt;
+	}
+
 	vsk = vsock_sk(sk);
 
 	lock_sock(sk);
-- 
2.25.1