Re: [PATCH net-next v5 2/2] selftests/net/openvswitch: add SCTP flow key test across conntrack NAT

On Fri, Sep 18, 2026 at 10:46:47AM -0400, Minxi Hou wrote:

After conntrack NAT rewrites a packet, OVS refreshes the cached flow
key in ovs_nat_update_key(), which has a per-protocol branch for the
L4 ports (UDP/TCP/SCTP, conntrack.c). Address-only NAT cannot tell a
working SCTP branch from a missing one: the ports survive unchanged
either way, so a post-recirc match on the original port stays green
even with the branch deleted. The suite's NAT coverage drives TCP
over nc, and the merged SCTP test has no conntrack in the path, so
the SCTP branch goes unexercised.

Add test_sctp_nat_connect_v4: untracked client traffic to
192.168.0.20:4443 hits ct(commit,nat(dst=172.31.110.20:5555)),recirc,
and the post-recirc flows match the translated tuple,
ipv4(dst=172.31.110.20),sctp(dst=5555). Reply traffic is matched on
the restored original tuple, sctp(src=4443). With the SCTP branch
broken the translated port never reaches the key, no post-recirc
flow matches, and the association fails. The probe flow uses the
same ct+nat action as the real flows, so a kernel without
CONFIG_NF_NAT rejects it at flow-add time and the test skips instead
of failing. The config fragment sets CONFIG_NETFILTER_ADVANCED=y so
CONFIG_NF_CT_PROTO_SCTP is visible, CONFIG_NF_CT_PROTO_SCTP=y, and
CONFIG_NF_NAT=m so the reference build actually has those pieces.
After the association succeeds the test pushes a known payload
across and waits for the listener to log it.

Signed-off-by: Minxi Hou <redacted>
---
 .../testing/selftests/net/openvswitch/config  |  3 +
 .../selftests/net/openvswitch/openvswitch.sh  | 93 +++++++++++++++++++
 2 files changed, 96 insertions(+)

Reviewed-by: Narcisa Vasile <redacted>