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

From: Stefano Garzarella <sgarzare@redhat.com>
To: netdev@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org,
	Jorgen Hansen <jhansen@vmware.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Adit Ranadive <aditr@vmware.com>,
	Jason Wang <jasowang@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net 2/2] vhost/vsock: don't allow half-closed socket in the host
Date: Fri, 11 Oct 2019 15:07:58 +0200	[thread overview]
Message-ID: <20191011130758.22134-3-sgarzare@redhat.com> (raw)
In-Reply-To: <20191011130758.22134-1-sgarzare@redhat.com>

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@redhat.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

