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

Jason Wang
2020-04-28T08:13:52Z

On 2020/4/27 下午10:25, 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?

As we've discussed, it should be a netdev probably in either guest or
host side. And it would be much simpler if we want do implement
namespace then. No new API is needed.

Thanks

>
>
> 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?
>
> - 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
>>