[PATCH net-next v10] selftests/net/openvswitch: add SCTP flow key support and test

[Minxi Hou <houminxi@gmail.com>]

The ovskey flow-string parser has no OVS_KEY_ATTR_SCTP entry, so a
flow string containing sctp(src=.../dst=...) parses without error but
silently drops the L4 key. The resulting flow carries only
ipv4(proto=132), and the kernel rejects it: match_validate() in
flow_netlink.c requires OVS_KEY_ATTR_SCTP when the IP protocol is
IPPROTO_SCTP and returns -EINVAL for the missing key.

Register OVS_KEY_ATTR_SCTP in the parse table and add a matching
selftest that verifies SCTP flow key matching (sctp src/dst port).

One listener serves the whole test. socat's fork option handles each
association in a child, so the flow rules are the only thing that
changes between the three phases and the listener is never restarted
underneath them. -t 1 bounds how long a forked child lingers after
its association closes, and the existing kill -TERM of the captured
pid on teardown removes the listener itself.

Also enable CONFIG_IP_SCTP in the selftest kernel config. The config
checker strips underscores before comparing keys, so the entry sorts
before CONFIG_IPV6 rather than after it.

Signed-off-by: Minxi Hou <houminxi@gmail.com>
---
v10:
  - drop the sctp() key probe. OVS_KEY_ATTR_SCTP is unconditional in
    the kernel datapath (no kconfig gates it in flow_netlink.c), so
    the probe only ever fired for a missing ovs-dpctl.py parse-table
    entry and turned that regression into a skip: the same gap that
    hid the v5 loss. A parse-table regression now fails the test
    instead of skipping it (Jakub)
  - drop setsid. The forked children exit when their association
    closes, socat -t 1 bounds how long they linger, and the existing
    kill -TERM of the captured pid removes the listener itself (Jakub)
  - bound listener child lifetime with socat -t 1 (Jakub)
v9:
  - one forking listener for the whole test instead of restarting it
    between phases (Aaron)
  - signal the daemon's process group on cleanup so the children a
    forking listener leaves behind are reaped
  - sort CONFIG_IP_SCTP the way the config checker compares keys
v8: https://lore.kernel.org/netdev/20260731062655.4088575-1-houminxi@gmail.com/
v7: https://lore.kernel.org/netdev/20260729064549.3647518-1-houminxi@gmail.com/
v6: https://lore.kernel.org/netdev/20260724150624.3457427-1-houminxi@gmail.com/
v5: https://lore.kernel.org/netdev/20260723084203.3483560-1-houminxi@gmail.com/
v4: https://lore.kernel.org/netdev/20260719162657.3263089-1-houminxi@gmail.com/
v3: https://lore.kernel.org/netdev/20260715015446.530018-1-houminxi@gmail.com/
v2: https://lore.kernel.org/netdev/20260707034718.2717982-1-houminxi@gmail.com/
v1: https://lore.kernel.org/netdev/20260702090908.1253688-1-houminxi@gmail.com/
---
 .../testing/selftests/net/openvswitch/config  |  1 +
 .../selftests/net/openvswitch/openvswitch.sh  | 90 +++++++++++++++++++
 .../selftests/net/openvswitch/ovs-dpctl.py    |  5 ++
 3 files changed, 96 insertions(+)

diff --git a/tools/testing/selftests/net/openvswitch/config b/tools/testing/selftests/net/openvswitch/config
index 05ca6affb510..a825e0b5c88e 100644
--- a/tools/testing/selftests/net/openvswitch/config
+++ b/tools/testing/selftests/net/openvswitch/config
@@ -1,5 +1,6 @@
 CONFIG_GENEVE=m
 CONFIG_INET_DIAG=y
+CONFIG_IP_SCTP=y
 CONFIG_IPV6=y
 CONFIG_NETFILTER=y
 CONFIG_NET_IPGRE=m
diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
index f63001dc2510..a31f7fb6882d 100755
--- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
+++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
@@ -33,6 +33,7 @@ tests="
 	action_set				set: SET action rewrites fields
 	trunc					trunc: output truncation
 	icmpv6					icmpv6: ICMPv6 echo type match
+	sctp_connect_v4				sctp: SCTP flow key matching
 	psample					psample: Sampling packets with psample"
 
 info() {
@@ -610,6 +611,95 @@ test_icmpv6() {
 	return 0
 }
 
+# Check for an SCTP endpoint via /proc, which works without sctp_diag.
+sctp_eps_has() {
+	ip netns exec "$1" awk -v p="$2" '$6==p' /proc/net/sctp/eps | grep -q .
+}
+
+# sctp_connect_v4 test
+# - sctp(dst=4443) matches client-to-server INIT
+# - sctp(src=4443) matches server-to-client INIT-ACK
+# - remove flows and verify connection fails, reinstall and recover
+test_sctp_connect_v4() {
+	local t="test_sctp_connect_v4"
+	local srv_ip=172.31.110.20
+
+	modprobe -q sctp 2>/dev/null || return "$ksft_skip"
+	socat -V 2>&1 | grep -q "define WITH_SCTP" || return "$ksft_skip"
+
+	sbx_add "$t" || return $?
+	ovs_add_dp "$t" sctp4 || return 1
+
+	info "create namespaces"
+	for ns in client server; do
+		ovs_add_netns_and_veths "$t" "sctp4" "$ns" \
+		    "${ns:0:1}0" "${ns:0:1}1" || return 1
+	done
+
+	ip netns exec client ip addr add 172.31.110.10/24 dev c1
+	ip netns exec client ip link set c1 up
+	ip netns exec server ip addr add "${srv_ip}/24" dev s1
+	ip netns exec server ip link set s1 up
+
+	# ARP forwarding
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(1),eth(),eth_type(0x0806),arp()' \
+	    '2' || return 1
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0806),arp()' \
+	    '1' || return 1
+
+	# SCTP port matching: dst for request, src for reply
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(1),eth(),eth_type(0x0800),ipv4(proto=132),sctp(dst=4443)' \
+	    '2' || return 1
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0800),ipv4(proto=132),sctp(src=4443)' \
+	    '1' || return 1
+
+	# The listener forks a child per association, so one instance serves
+	# the whole test and the flows stay the only variable. -t 1 bounds
+	# how long a child lingers after its association closes.
+	ovs_netns_spawn_daemon "$t" "server" \
+	    socat -u -t 1 SCTP4-LISTEN:4443,fork STDOUT
+	ovs_wait sctp_eps_has server 4443 || return 1
+
+	info "verify SCTP association with port-keyed flows"
+	ovs_sbx "$t" ip netns exec client \
+	    timeout 3 socat -u STDIN "SCTP4-CONNECT:${srv_ip}:4443" </dev/null \
+	    || return 1
+
+	ovs_del_flows "$t" sctp4
+
+	info "verify connection fails without flows"
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(1),eth(),eth_type(0x0806),arp()' \
+	    '2' || return 1
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0806),arp()' \
+	    '1' || return 1
+
+	ovs_sbx "$t" ip netns exec client \
+	    timeout 3 socat -u STDIN "SCTP4-CONNECT:${srv_ip}:4443" </dev/null \
+	    >/dev/null 2>&1 \
+	    && { info "connection should fail without flows"
+	         return 1; }
+
+	info "reinstall flows and verify recovery"
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(1),eth(),eth_type(0x0800),ipv4(proto=132),sctp(dst=4443)' \
+	    '2' || return 1
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0800),ipv4(proto=132),sctp(src=4443)' \
+	    '1' || return 1
+
+	ovs_sbx "$t" ip netns exec client \
+	    timeout 3 socat -u STDIN "SCTP4-CONNECT:${srv_ip}:4443" </dev/null \
+	    || return 1
+
+	return 0
+}
+
 # psample test
 # - use psample to observe packets
 test_psample() {
diff --git a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
index 3ece07d47281..1615843c225e 100644
--- a/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
+++ b/tools/testing/selftests/net/openvswitch/ovs-dpctl.py
@@ -1984,6 +1984,11 @@ class ovskey(nla):
                 "udp",
                 ovskey.ovs_key_udp,
             ),
+            (
+                "OVS_KEY_ATTR_SCTP",
+                "sctp",
+                ovskey.ovs_key_sctp,
+            ),
             (
                 "OVS_KEY_ATTR_ICMP",
                 "icmp",
-- 
2.55.0