[RFC PATCH v3 09/13] virtio/vsock: add SEQPACKET receive logic

[Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 net/vmw_vsock/virtio_transport_common.c | 79 ++++++++++++++++++-------
 1 file changed, 58 insertions(+), 21 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index dcce35d7b462..90f9feef9d8f 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -397,6 +397,14 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 	return err;
 }
 
+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;
+}
+
 static inline void virtio_transport_del_n_free_pkt(struct virtio_vsock_pkt *pkt)
 {
 	list_del(&pkt->list);
@@ -1050,39 +1058,49 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
 			      struct virtio_vsock_pkt *pkt)
 {
 	struct virtio_vsock_sock *vvs = vsk->trans;
-	bool can_enqueue, free_pkt = false;
+	bool free_pkt = false;
 
 	pkt->len = le32_to_cpu(pkt->hdr.len);
 	pkt->off = 0;
 
 	spin_lock_bh(&vvs->rx_lock);
 
-	can_enqueue = virtio_transport_inc_rx_pkt(vvs, pkt);
-	if (!can_enqueue) {
+	if (!virtio_transport_inc_rx_pkt(vvs, pkt)) {
 		free_pkt = true;
 		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;
+	switch (le16_to_cpu(pkt->hdr.type)) {
+	case 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;
+			}
 		}
+
+		break;
+	}
+	case VIRTIO_VSOCK_TYPE_SEQPACKET: {
+		break;
+	}
+	default:
+		goto out;
 	}
 
 	list_add_tail(&pkt->list, &vvs->rx_queue);
@@ -1101,6 +1119,14 @@ virtio_transport_recv_connected(struct sock *sk,
 	int err = 0;
 
 	switch (le16_to_cpu(pkt->hdr.op)) {
+	case VIRTIO_VSOCK_OP_SEQ_BEGIN: {
+		struct virtio_vsock_sock *vvs = vsk->trans;
+
+		spin_lock_bh(&vvs->rx_lock);
+		list_add_tail(&pkt->list, &vvs->rx_queue);
+		spin_unlock_bh(&vvs->rx_lock);
+		return err;
+	}
 	case VIRTIO_VSOCK_OP_RW:
 		virtio_transport_recv_enqueue(vsk, pkt);
 		sk->sk_data_ready(sk);
@@ -1247,6 +1273,12 @@ 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.
  */
@@ -1272,7 +1304,7 @@ 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;
 	}
@@ -1289,6 +1321,11 @@ 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);
 
 	space_available = virtio_transport_space_update(sk, pkt);
-- 
2.25.1