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Message-ID: <r6a6ihjw3etlb5chqsb65u7uhcav6q6pjxu65iqpp76423w2wd@kmctvoaywmbu>
Date: Fri, 28 Mar 2025 18:03:19 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Bobby Eshleman <bobbyeshleman@...il.com>,
Daniel Berrangé <berrange@...hat.com>
Cc: Jakub Kicinski <kuba@...nel.org>,
"K. Y. Srinivasan" <kys@...rosoft.com>, Haiyang Zhang <haiyangz@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
Stefan Hajnoczi <stefanha@...hat.com>, "Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>, Bryan Tan <bryan-bt.tan@...adcom.com>,
Vishnu Dasa <vishnu.dasa@...adcom.com>,
Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, "David S. Miller" <davem@...emloft.net>,
virtualization@...ts.linux.dev, netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-hyperv@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v2 0/3] vsock: add namespace support to vhost-vsock
CCing Daniel
On Wed, Mar 12, 2025 at 01:59:34PM -0700, Bobby Eshleman wrote:
>Picking up Stefano's v1 [1], this series adds netns support to
>vhost-vsock. Unlike v1, this series does not address guest-to-host (g2h)
>namespaces, defering that for future implementation and discussion.
>
>Any vsock created with /dev/vhost-vsock is a global vsock, accessible
>from any namespace. Any vsock created with /dev/vhost-vsock-netns is a
>"scoped" vsock, accessible only to sockets in its namespace. If a global
>vsock or scoped vsock share the same CID, the scoped vsock takes
>precedence.
>
>If a socket in a namespace connects with a global vsock, the CID becomes
>unavailable to any VMM in that namespace when creating new vsocks. If
>disconnected, the CID becomes available again.
I was talking about this feature with Daniel and he pointed out
something interesting (Daniel please feel free to correct me):
If we have a process in the host that does a listen(AF_VSOCK) in a
namespace, can this receive connections from guests connected to
/dev/vhost-vsock in any namespace?
Should we provide something (e.g. sysctl/sysfs entry) to disable
this behaviour, preventing a process in a namespace from receiving
connections from the global vsock address space (i.e.
/dev/vhost-vsock VMs)?
I understand that by default maybe we should allow this behaviour in
order to not break current applications, but in some cases the user may
want to isolate sockets in a namespace also from being accessed by VMs
running in the global vsock address space.
Indeed in this series we have talked mostly about the host -> guest path
(as the direction of the connection), but little about the guest -> host
path, maybe we should explain it better in the cover/commit
descriptions/documentation.
Thanks,
Stefano
>
>Testing
>
>QEMU with /dev/vhost-vsock-netns support:
> https://github.com/beshleman/qemu/tree/vsock-netns
>
>Test: Scoped vsocks isolated by namespace
>
> host# ip netns add ns1
> host# ip netns add ns2
> host# ip netns exec ns1 \
> qemu-system-x86_64 \
> -m 8G -smp 4 -cpu host -enable-kvm \
> -serial mon:stdio \
> -drive if=virtio,file=${IMAGE1} \
> -device vhost-vsock-pci,netns=on,guest-cid=15
> host# ip netns exec ns2 \
> qemu-system-x86_64 \
> -m 8G -smp 4 -cpu host -enable-kvm \
> -serial mon:stdio \
> -drive if=virtio,file=${IMAGE2} \
> -device vhost-vsock-pci,netns=on,guest-cid=15
>
> host# socat - VSOCK-CONNECT:15:1234
> 2025/03/10 17:09:40 socat[255741] E connect(5, AF=40 cid:15 port:1234, 16): No such device
>
> host# echo foobar1 | sudo ip netns exec ns1 socat - VSOCK-CONNECT:15:1234
> host# echo foobar2 | sudo ip netns exec ns2 socat - VSOCK-CONNECT:15:1234
>
> vm1# socat - VSOCK-LISTEN:1234
> foobar1
> vm2# socat - VSOCK-LISTEN:1234
> foobar2
>
>Test: Global vsocks accessible to any namespace
>
> host# qemu-system-x86_64 \
> -m 8G -smp 4 -cpu host -enable-kvm \
> -serial mon:stdio \
> -drive if=virtio,file=${IMAGE2} \
> -device vhost-vsock-pci,guest-cid=15,netns=off
>
> host# echo foobar | sudo ip netns exec ns1 socat - VSOCK-CONNECT:15:1234
>
> vm# socat - VSOCK-LISTEN:1234
> foobar
>
>Test: Connecting to global vsock makes CID unavailble to namespace
>
> host# qemu-system-x86_64 \
> -m 8G -smp 4 -cpu host -enable-kvm \
> -serial mon:stdio \
> -drive if=virtio,file=${IMAGE2} \
> -device vhost-vsock-pci,guest-cid=15,netns=off
>
> vm# socat - VSOCK-LISTEN:1234
>
> host# sudo ip netns exec ns1 socat - VSOCK-CONNECT:15:1234
> host# ip netns exec ns1 \
> qemu-system-x86_64 \
> -m 8G -smp 4 -cpu host -enable-kvm \
> -serial mon:stdio \
> -drive if=virtio,file=${IMAGE1} \
> -device vhost-vsock-pci,netns=on,guest-cid=15
>
> qemu-system-x86_64: -device vhost-vsock-pci,netns=on,guest-cid=15: vhost-vsock: unable to set guest cid: Address already in use
>
>Signed-off-by: Bobby Eshleman <bobbyeshleman@...il.com>
>---
>Changes in v2:
>- only support vhost-vsock namespaces
>- all g2h namespaces retain old behavior, only common API changes
> impacted by vhost-vsock changes
>- add /dev/vhost-vsock-netns for "opt-in"
>- leave /dev/vhost-vsock to old behavior
>- removed netns module param
>- Link to v1: https://lore.kernel.org/r/20200116172428.311437-1-sgarzare@redhat.com
>
>Changes in 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
>- Link to RFC: https://patchwork.ozlabs.org/cover/1202235/
>
>---
>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-netns device
>
> drivers/vhost/vsock.c | 96 +++++++++++++++++++++++++++------
> include/linux/miscdevice.h | 1 +
> include/linux/virtio_vsock.h | 2 +
> include/net/af_vsock.h | 10 ++--
> net/vmw_vsock/af_vsock.c | 85 +++++++++++++++++++++++------
> net/vmw_vsock/hyperv_transport.c | 2 +-
> net/vmw_vsock/virtio_transport.c | 5 +-
> net/vmw_vsock/virtio_transport_common.c | 14 ++++-
> net/vmw_vsock/vmci_transport.c | 4 +-
> net/vmw_vsock/vsock_loopback.c | 4 +-
> 10 files changed, 180 insertions(+), 43 deletions(-)
>---
>base-commit: 0ea09cbf8350b70ad44d67a1dcb379008a356034
>change-id: 20250312-vsock-netns-45da9424f726
>
>Best regards,
>--
>Bobby Eshleman <bobbyeshleman@...il.com>
>
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