Re: [PATCH v2] virtio/vsock: fix the transport to work with VMADDR_CID_ANY

[Stefano Garzarella]

On Thu, Nov 25, 2021 at 08:18:23PM -0500, Wei Wang wrote:
> The VMADDR_CID_ANY flag used by a socket means that the socket isn't bound
> to any specific CID. For example, a host vsock server may want to be bound
> with VMADDR_CID_ANY, so that a guest vsock client can connect to the host
> server with CID=VMADDR_CID_HOST (i.e. 2), and meanwhile, a host vsock
> client can connect to the same local server with CID=VMADDR_CID_LOCAL
> (i.e. 1).
>
> The current implementation sets the destination socket's svm_cid to a
> fixed CID value after the first client's connection, which isn't an
> expected operation. For example, if the guest client first connects to the
> host server, the server's svm_cid gets set to VMADDR_CID_HOST, then other
> host clients won't be able to connect to the server anymore.
>
> Reproduce steps:
> 1. Run the host server:
>   socat VSOCK-LISTEN:1234,fork -
> 2. Run a guest client to connect to the host server:
>   socat - VSOCK-CONNECT:2:1234
> 3. Run a host client to connect to the host server:
>   socat - VSOCK-CONNECT:1:1234
>
> Without this patch, step 3. above fails to connect, and socat complains
> "socat[1720] E connect(5, AF=40 cid:1 port:1234, 16): Connection
> reset by peer".
> With this patch, the above works well.
>
> Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
> Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx>
> ---
> net/vmw_vsock/virtio_transport_common.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)

Usually fixes for net/vmw_vsock/* are applied through the net tree 
(netdev@xxxxxxxxxxxxxxx) that seems not CCed. Please use 
./scripts/get_maintainer.pl next time.

Maybe this one can be queued by Michael, let's wait a bit, otherwise 
please resend CCing netdev and using "net" tag.

Anyway the patch LGTM:

Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>