On Wed, Sep 02, 2026 at 04:00:49PM -0700, Bobby Eshleman wrote:
> From: Bobby Eshleman <[email protected]>
>
> virtio-vsock did not have namespace support (the device was always
> accessible to any global namespace).
>
> Make the virtio-vsock device assignable to a namespace and initialize it
> to init_net. Because virtio-vsock and init_net are both hardcoded to
> global mode, nothing changes until the assign ioctl is issued.
>
> When the device's local-mode namespace is being destroyed, received
> packets are reset until new valid a namespace has been assigned and/or
> automatically returned to, and the next RX batch begins (in
> virtio_transport_rx_work). They are reset rather than dropped because
> vsock does not retransmit, so a silent drop would leave the host waiting
> for a timeout, and a connection request arriving in that window has no
> socket whose teardown would tell it otherwise. This requires making
> virtio_transport_reset_no_sock() available outside of the common code.
>
> When a device is assigned to a namespace, every already established
> vsock socket that is no longer able to reach the device is forcibly
> reset. For that reason, adding new sockets to the connected table must
> be performed atomically with regards to namespace assignment. This
> ensures that when the socket is added to the connected table that it
> actually passes the new reachability conditions set by ns assignment. If
> it wins the race to the table and does NOT pass the reachability tests,
> then the reset sweep will correctly catch it. This is the purpose
> of the new helper 'vsock_maybe_set_connected()'.
>
> Signed-off-by: Bobby Eshleman <[email protected]>
> ---
> include/linux/virtio_vsock.h | 2 ++
> net/vmw_vsock/virtio_transport.c | 28 ++++++++++++++++++++++------
> net/vmw_vsock/virtio_transport_common.c | 28 +++++++++++++++++++++-------
> 3 files changed, 45 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
> index f91704731057..9c68ce1d7fb4 100644
> --- a/include/linux/virtio_vsock.h
> +++ b/include/linux/virtio_vsock.h
> @@ -286,6 +286,8 @@ void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock
*vvs, struct sk_buff *
> u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 wanted);
> void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit);
> void virtio_transport_deliver_tap_pkt(struct sk_buff *skb);
> +int virtio_transport_reset_no_sock(const struct virtio_transport *t,
> + struct sk_buff *skb, struct net *net);
> int virtio_transport_purge_skbs(void *vsk, struct sk_buff_head *list);
> int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t
read_actor);
> int virtio_transport_notify_set_rcvlowat(struct vsock_sock *vsk, int val);
> diff --git a/net/vmw_vsock/virtio_transport.c
b/net/vmw_vsock/virtio_transport.c
> index 4f9aa9c4c3aa..a453a4f828dc 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -540,9 +540,14 @@ static bool virtio_transport_msgzerocopy_allow(void)
> return true;
> }
>
> +static bool virtio_transport_netns_assign_allow(void)
> +{
> + return true;
> +}
> +
> bool virtio_transport_stream_allow(struct vsock_sock *vsk, u32 cid, u32 port)
> {
> - return vsock_net_mode_global(vsk);
> + return vsock_g2h_net_reachable(sock_net(sk_vsock(vsk)));
> }
>
> static bool virtio_transport_seqpacket_allow(struct vsock_sock *vsk,
> @@ -587,6 +592,7 @@ static struct virtio_transport virtio_transport = {
> .seqpacket_has_data = virtio_transport_seqpacket_has_data,
>
> .msgzerocopy_allow = virtio_transport_msgzerocopy_allow,
> + .netns_assign_allow = virtio_transport_netns_assign_allow,
>
> .notify_poll_in = virtio_transport_notify_poll_in,
> .notify_poll_out = virtio_transport_notify_poll_out,
> @@ -616,7 +622,7 @@ virtio_transport_seqpacket_allow(struct vsock_sock *vsk,
u32 remote_cid)
> struct virtio_vsock *vsock;
> bool seqpacket_allow;
>
> - if (!vsock_net_mode_global(vsk))
> + if (!vsock_g2h_net_reachable(sock_net(sk_vsock(vsk))))
> return false;
>
> seqpacket_allow = false;
> @@ -634,6 +640,9 @@ static void virtio_transport_rx_work(struct work_struct
*work)
> struct virtio_vsock *vsock =
> container_of(work, struct virtio_vsock, rx_work);
> struct virtqueue *vq;
> + struct net *net;
> +
> + net = vsock_g2h_net_get();
>
> mutex_lock(&vsock->rx_lock);
>
> @@ -682,10 +691,14 @@ static void virtio_transport_rx_work(struct work_struct
*work)
>
> virtio_transport_deliver_tap_pkt(skb);
>
> - /* Force virtio-transport into global mode since it
> - * does not yet support local-mode namespacing.
> - */
> - virtio_transport_recv_pkt(&virtio_transport, skb, NULL);
> + if (unlikely(!net)) {
> + virtio_transport_reset_no_sock(
> + &virtio_transport, skb, &init_net);
Why init_net?
