On Wed, 5 Mar 2025 at 10:29, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Wed, Mar 05, 2025 at 10:23:08AM +0100, Stefano Garzarella wrote: > > On Wed, 5 Mar 2025 at 08:32, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > > > > > On Thu, Jan 16, 2020 at 06:24:26PM +0100, Stefano Garzarella wrote: > > > > This patch adds a check of the "net" assigned to a socket during > > > > the vsock_find_bound_socket() and vsock_find_connected_socket() > > > > to support network namespace, allowing to share the same address > > > > (cid, port) across different network namespaces. > > > > > > > > This patch adds 'netns' module param to enable this new feature > > > > (disabled by default), because it changes vsock's behavior with > > > > network namespaces and could break existing applications. > > > > G2H transports will use the default network namepsace (init_net). > > > > H2G transports can use different network namespace for different > > > > VMs. > > > > > > > > > I'm not sure I understand the usecase. Can you explain a bit more, > > > please? > > > > It's been five years, but I'm trying! > > We are tracking this RFE here [1]. > > > > I also add Jakub in the thread with who I discussed last year a possible > > restart of this effort, he could add more use cases. > > > > The problem with vsock, host-side, currently is that if you launch a VM > > with a virtio-vsock device (using vhost) inside a container (e.g., > > Kata), so inside a network namespace, it is reachable from any other > > container, whereas they would like some isolation. Also the CID is > > shared among all, while they would like to reuse the same CID in > > different namespaces. > > > > This has been partially solved with vhost-user-vsock, but it is > > inconvenient to use sometimes because of the hybrid-vsock problem > > (host-side vsock is remapped to AF_UNIX). > > > > Something from the cover letter of the series [2]: > > > > As we partially discussed in the multi-transport proposal, it could > > be nice to support network namespace in vsock to reach the following > > goals: > > - isolate host applications from guest applications using the same ports > > with CID_ANY > > - assign the same CID of VMs running in different network namespaces > > - partition VMs between VMMs or at finer granularity > > > > Thanks, > > Stefano > > > > [1] https://gitlab.com/vsock/vsock/-/issues/2 > > [2] https://lore.kernel.org/virtualization/20200116172428.311437-1-sgarzare@xxxxxxxxxx/ > > > Ok so, host side. I get it. Now that we're talking about it, I also came back to a guest side case, again related to containers and possible nested VMs. If you launch a container in a L1 guest, for example to launch a nested VM, maybe you don't want to have it communicate with the L0 host, so it would be desirable to be able to isolate the virtio-vsock device from it. > And the problem with your patches is that > they affect the guest side. Fix that, basically. My main problem, IIRC, was making sure to allow the old behavior as well (but that maybe we had solved with two /dev/vhost-vsock and /dev/vhost-vsock-netns). The other problem was really in the guest, on how to tell that the virtio-vsock device (thus communication with the host) was reachable from a netnamespace or not. Stefano
