On Thu, Nov 06, 2025 at 06:52:15PM -0800, Bobby Eshleman wrote:
On Thu, Nov 06, 2025 at 05:20:05PM +0100, Stefano Garzarella wrote:
On Thu, Oct 23, 2025 at 11:27:45AM -0700, Bobby Eshleman wrote:
From: Bobby Eshleman bobbyeshleman@meta.com
Enable network namespace support in the virtio-vsock common transport layer by declaring namespace pointers in the transmit and receive paths.
The changes include:
- Add a 'net' field to virtio_vsock_pkt_info to carry the namespace
pointer for outgoing packets. 2. Store the namespace and namespace mode in the skb control buffer when allocating packets (except for VIRTIO_VSOCK_OP_RST packets which do not have an associated socket). 3. Retrieve namespace information from skbs on the receive path for lookups using vsock_find_connected_socket_net() and vsock_find_bound_socket_net().
This allows users of virtio transport common code (vhost-vsock/virtio-vsock) to later enable namespace support.
Signed-off-by: Bobby Eshleman bobbyeshleman@meta.com
Changes in v7:
- add comment explaining the !vsk case in
virtio_transport_alloc_skb()
include/linux/virtio_vsock.h | 1 + net/vmw_vsock/virtio_transport_common.c | 21 +++++++++++++++++++-- 2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h index 29290395054c..f90646f82993 100644 --- a/include/linux/virtio_vsock.h +++ b/include/linux/virtio_vsock.h @@ -217,6 +217,7 @@ struct virtio_vsock_pkt_info { u32 remote_cid, remote_port; struct vsock_sock *vsk; struct msghdr *msg;
- struct net *net; u32 pkt_len; u16 type; u16 op;
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index dcc8a1d5851e..b8e52c71920a 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -316,6 +316,15 @@ static struct sk_buff *virtio_transport_alloc_skb(struct virtio_vsock_pkt_info * info->flags, zcopy);
- /*
* If there is no corresponding socket, then we don't have a* corresponding namespace. This only happens For VIRTIO_VSOCK_OP_RST.*/So, in virtio_transport_recv_pkt() should we check that `net` is not set?
Should we set it to NULL here?
Sounds good to me.
- if (vsk) {
virtio_vsock_skb_set_net(skb, info->net);Ditto here about the net refcnt, can the net disappear? Should we use get_net() in some way, or the socket will prevent that?
As long as the socket has an outstanding skb it can't be destroyed and so will have a reference to the net, that is after skb_set_owner_w() and freeing... so I think this is okay.
But, maybe we could simplify the implied relationship between skb, sk, and net by removing the VIRTIO_VSOCK_SKB_CB(skb)->net entirely, and only ever referring to sock_net(skb->sk)? I remember originally having a reason for adding it to the cb, but my hunch is it that it was probably some confusion over the !vsk case.
WDYT?
If vsk == NULL, I'm expecting that also skb->sk is not valid, right?
Indeed we call skb_set_owner_w() only if vsk != NULL in virtio_transport_alloc_skb().
Maybe we need to change virtio_transport_recv_pkt() where the `net` should be passed in some way by the caller, so maybe this is the reason why you needed it in the cb. But also in that case, I think we can get the `net` in some way and pass it to virtio_transport_recv_pkt() and avoid the change in the cb: - vsock_lookpback.c in vsock_loopback_work() we can use vsock->net - vhost/vsock.c in vhost_vsock_handle_tx_kick(), ditto we can use vsock->net - virtio_transport.c we can just pass always the dummy_net
Same fot the net_mode.
Maybe the real problem is in the send_pkt callbacks, where the skb is used to get the socket, but as you mention, I think in this path skb_set_owner_w() is already called, so we can get that info from there in some way.
Not sure, but yeah, if we can remove that, it will be much clear IMO.
Thanks, Stefano