[PATCH RFC net-next v4 00/12] vsock: add namespace support to vhost-vsock

[Bobby Eshleman <bobbyeshleman@gmail.com>]

This series adds namespace support to vhost-vsock. It does not add
namespaces to any of the guest transports (virtio-vsock, hyperv, or
vmci).

The current revision only supports two modes: local or global. Local
mode is complete isolation of namespaces, while global mode is complete
sharing between namespaces of CIDs (the original behavior).

Future may include supporting a mixed mode, which I expect to be more
complicated because socket lookups will have to include new logic and
API changes to behave differently based on if the lookup is part of a
mixed mode CID allocation, a global CID allocation, a mixed-to-global
connection (allowed), or a global-to-mixed connection (not allowed).

Modes are per-netns and write-once. This allows a system to configure
namespaces independently (some may share CIDs, others are completely
isolated). This also supports future mixed use cases, where there may be
namespaces in global mode spinning up VMs while there are
mixed mode namespaces that provide services to the VMs, but are not
allowed to allocate from the global CID pool.

Thanks again for everyone's help and reviews!

Signed-off-by: Bobby Eshleman <bobbyeshleman@gmail.com>
To: Stefano Garzarella <sgarzare@redhat.com>
To: Shuah Khan <shuah@kernel.org>
To: David S. Miller <davem@davemloft.net>
To: Eric Dumazet <edumazet@google.com>
To: Jakub Kicinski <kuba@kernel.org>
To: Paolo Abeni <pabeni@redhat.com>
To: Simon Horman <horms@kernel.org>
To: Stefan Hajnoczi <stefanha@redhat.com>
To: Michael S. Tsirkin <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
To: Eugenio Pérez <eperezma@redhat.com>
To: K. Y. Srinivasan <kys@microsoft.com>
To: Haiyang Zhang <haiyangz@microsoft.com>
To: Wei Liu <wei.liu@kernel.org>
To: Dexuan Cui <decui@microsoft.com>
To: Bryan Tan <bryan-bt.tan@broadcom.com>
To: Vishnu Dasa <vishnu.dasa@broadcom.com>
To: Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
Cc: virtualization@lists.linux.dev
Cc: netdev@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-hyperv@vger.kernel.org
Cc: berrange@redhat.com

Changes in v4:
- removed RFC tag
- implemented loopback support
- renamed new tests to better reflect behavior
- completed suite of tests with permutations of ns modes and vsock_test
  as guest/host
- simplified socat bridging with unix socket instead of tcp + veth
- only use vsock_test for success case, socat for failure case (context
  in commit message)
- lots of cleanup

Changes in v3:
- add notion of "modes"
- add procfs /proc/net/vsock_ns_mode
- local and global modes only
- no /dev/vhost-vsock-netns
- vmtest.sh already merged, so new patch just adds new tests for NS
- Link to v2:
  https://lore.kernel.org/kvm/20250312-vsock-netns-v2-0-84bffa1aa97a@gmail.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/

---
Bobby Eshleman (12):
      vsock: a per-net vsock NS mode state
      vsock: add net to vsock skb cb
      vsock: add netns to af_vsock core
      vsock/virtio: add netns to virtio transport common
      vhost/vsock: add netns support
      vsock/virtio: use the global netns
      hv_sock: add netns hooks
      vsock/vmci: add netns hooks
      vsock/loopback: add netns support
      selftests/vsock: improve logging in vmtest.sh
      selftests/vsock: invoke vsock_test through helpers
      selftests/vsock: add namespace tests

 MAINTAINERS                             |    1 +
 drivers/vhost/vsock.c                   |   48 +-
 include/linux/virtio_vsock.h            |   12 +
 include/net/af_vsock.h                  |   59 +-
 include/net/net_namespace.h             |    4 +
 include/net/netns/vsock.h               |   21 +
 net/vmw_vsock/af_vsock.c                |  204 +++++-
 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          |   59 +-
 tools/testing/selftests/vsock/vmtest.sh | 1088 ++++++++++++++++++++++++++-----
 13 files changed, 1330 insertions(+), 191 deletions(-)
---
base-commit: dd500e4aecf25e48e874ca7628697969df679493
change-id: 20250325-vsock-vmtest-b3a21d2102c2

Best regards,
-- 
Bobby Eshleman <bobbyeshleman@meta.com>