netdev - [PATCH net 2/2] vhost/vsock: don't allow half-closed socket in the host

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Date:   Fri, 11 Oct 2019 15:07:58 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     netdev@...r.kernel.org
Cc:     virtualization@...ts.linux-foundation.org,
        Jorgen Hansen <jhansen@...are.com>,
        "David S. Miller" <davem@...emloft.net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Adit Ranadive <aditr@...are.com>,
        Jason Wang <jasowang@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net 2/2] vhost/vsock: don't allow half-closed socket in the host

vmci_transport never allowed half-closed socket on the host side.
In order to provide the same behaviour, we changed the
vhost_transport_stream_has_data() to return 0 (no data available)
if the peer (guest) closed the connection.

Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
---
 drivers/vhost/vsock.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 9f57736fe15e..754120aa4478 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -58,6 +58,21 @@ static u32 vhost_transport_get_local_cid(void)
 	return VHOST_VSOCK_DEFAULT_HOST_CID;
 }
 
+static s64 vhost_transport_stream_has_data(struct vsock_sock *vsk)
+{
+	/* vmci_transport doesn't allow half-closed socket on the host side.
+	 * recv() on the host side returns EOF when the guest closes a
+	 * connection, also if some data is still in the receive queue.
+	 *
+	 * In order to provide the same behaviour, we always return 0
+	 * (no data available) if the peer (guest) closed the connection.
+	 */
+	if (vsk->peer_shutdown == SHUTDOWN_MASK)
+		return 0;
+
+	return virtio_transport_stream_has_data(vsk);
+}
+
 /* Callers that dereference the return value must hold vhost_vsock_mutex or the
  * RCU read lock.
  */
@@ -804,7 +819,7 @@ static struct virtio_transport vhost_transport = {
 
 		.stream_enqueue           = virtio_transport_stream_enqueue,
 		.stream_dequeue           = virtio_transport_stream_dequeue,
-		.stream_has_data          = virtio_transport_stream_has_data,
+		.stream_has_data          = vhost_transport_stream_has_data,
 		.stream_has_space         = virtio_transport_stream_has_space,
 		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 		.stream_is_active         = virtio_transport_stream_is_active,
-- 
2.21.0