Re: [PATCH net-next 0/3] vsock: support network namespace

Michael S. Tsirkin
2020-04-27T14:32:13Z

On Mon, Apr 27, 2020 at 04:25:18PM +0200, Stefano Garzarella wrote:
> Hi David, Michael, Stefan,
> I'm restarting to work on this topic since Kata guys are interested to
> have that, especially on the guest side.
>
> While working on the v2 I had few doubts, and I'd like to have your
> suggestions:
>
> 1. netns assigned to the device inside the guest
>
> Currently I assigned this device to 'init_net'. Maybe it is better
> if we allow the user to decide which netns assign to the device
> or to disable this new feature to have the same behavior as before
> (host reachable from any netns).
> I think we can handle this in the vsock core and not in the single
> transports.
>
> The simplest way that I found, is to add a new
> IOCTL_VM_SOCKETS_ASSIGN_G2H_NETNS to /dev/vsock to enable the feature
> and assign the device to the same netns of the process that do the
> ioctl(), but I'm not sure it is clean enough.
>
> Maybe it is better to add new rtnetlink messages, but I'm not sure if
> it is feasible since we don't have a netdev device.
>
> What do you suggest?

Maybe /dev/vsock-netns here too, like in the host?

>
> 2. netns assigned in the host
>
> As Michael suggested, I added a new /dev/vhost-vsock-netns to allow
> userspace application to use this new feature, leaving to
> /dev/vhost-vsock the previous behavior (guest reachable from any
> netns).
>
> I like this approach, but I had these doubts:
>
> - I need to allocate a new minor for that device (e.g.
> VHOST_VSOCK_NETNS_MINOR) or is there an alternative way that I can
> use?

Not that I see. I agree it's a bit annoying. I'll think about it a bit.

> - It is vhost-vsock specific, should we provide something handled in
> the vsock core, maybe centralizing the CID allocation and adding a
> new IOCTL or rtnetlink message like for the guest side?
> (maybe it could be a second step, and for now we can continue with
> the new device)
>
>
> Thanks for the help,
> Stefano
>
>
> On Thu, Jan 16, 2020 at 06:24:25PM +0100, Stefano Garzarella wrote:
> > RFC -> v1:
> > * added 'netns' module param to vsock.ko to enable the
> > network namespace support (disabled by default)
> > * added 'vsock_net_eq()' to check the "net" assigned to a socket
> > only when 'netns' support is enabled
> >
> > RFC: https://patchwork.ozlabs.org/cover/1202235/
> >
> > Now that we have multi-transport upstream, I started to take a look to
> > support network namespace in vsock.
> >
> > As we partially discussed in the multi-transport proposal [1], 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
> >
> > This new feature is disabled by default, because it changes vsock's
> > behavior with network namespaces and could break existing applications.
> > It can be enabled with the new 'netns' module parameter of vsock.ko.
> >
> > This implementation provides the following behavior:
> > - packets received from the host (received by G2H transports) are
> > assigned to the default netns (init_net)
> > - packets received from the guest (received by H2G - vhost-vsock) are
> > assigned to the netns of the process that opens /dev/vhost-vsock
> > (usually the VMM, qemu in my tests, opens the /dev/vhost-vsock)
> > - for vmci I need some suggestions, because I don't know how to do
> > and test the same in the vmci driver, for now vmci uses the
> > init_net
> > - loopback packets are exchanged only in the same netns
> >
> > I tested the series in this way:
> > l0_host$ qemu-system-x86_64 -m 4G -M accel=kvm -smp 4 \
> > -drive file=/tmp/vsockvm0.img,if=virtio --nographic \
> > -device vhost-vsock-pci,guest-cid=3
> >
> > l1_vm$ echo 1 > /sys/module/vsock/parameters/netns
> >
> > l1_vm$ ip netns add ns1
> > l1_vm$ ip netns add ns2
> > # same CID on different netns
> > l1_vm$ ip netns exec ns1 qemu-system-x86_64 -m 1G -M accel=kvm -smp 2 \
> > -drive file=/tmp/vsockvm1.img,if=virtio --nographic \
> > -device vhost-vsock-pci,guest-cid=4
> > l1_vm$ ip netns exec ns2 qemu-system-x86_64 -m 1G -M accel=kvm -smp 2 \
> > -drive file=/tmp/vsockvm2.img,if=virtio --nographic \
> > -device vhost-vsock-pci,guest-cid=4
> >
> > # all iperf3 listen on CID_ANY and port 5201, but in different netns
> > l1_vm$ ./iperf3 --vsock -s # connection from l0 or guests started
> > # on default netns (init_net)
> > l1_vm$ ip netns exec ns1 ./iperf3 --vsock -s
> > l1_vm$ ip netns exec ns1 ./iperf3 --vsock -s
> >
> > l0_host$ ./iperf3 --vsock -c 3
> > l2_vm1$ ./iperf3 --vsock -c 2
> > l2_vm2$ ./iperf3 --vsock -c 2
> >
> > [1] https://www.spinics.net/lists/netdev/msg575792.html
> >
> > Stefano Garzarella (3):
> > vsock: add network namespace support
> > vsock/virtio_transport_common: handle netns of received packets
> > vhost/vsock: use netns of process that opens the vhost-vsock device
> >
> > drivers/vhost/vsock.c | 29 ++++++++++++-----
> > include/linux/virtio_vsock.h | 2 ++
> > include/net/af_vsock.h | 7 +++--
> > net/vmw_vsock/af_vsock.c | 41 +++++++++++++++++++------
> > net/vmw_vsock/hyperv_transport.c | 5 +--
> > net/vmw_vsock/virtio_transport.c | 2 ++
> > net/vmw_vsock/virtio_transport_common.c | 12 ++++++--
> > net/vmw_vsock/vmci_transport.c | 5 +--
> > 8 files changed, 78 insertions(+), 25 deletions(-)
> >
> > --
> > 2.24.1
> >