[PATCH net-next v6 2/2] selftests/net/openvswitch: add SCTP flow key test

[Minxi Hou <houminxi@gmail.com>]

Add test_sctp_connect_v4() to verify OVS can match on SCTP flow keys
(sctp src/dst port).

The test sets up client and server namespaces connected through an
OVS bridge, installs port-keyed flows, and verifies:
  - sctp(dst=4443) matches client-to-server INIT
  - sctp(src=4443) matches server-to-client INIT-ACK
  - removing flows drops the connection
  - reinstalling flows restores connectivity

The listener readiness probe reads /proc/net/sctp/eps instead of ss:
ss requires the sctp_diag interface, which is not enabled on all
kernels, while /proc/net/sctp/eps exists whenever SCTP is loaded.

Signed-off-by: Minxi Hou <houminxi@gmail.com>
---
 .../selftests/net/openvswitch/openvswitch.sh  | 121 ++++++++++++++++++
 1 file changed, 121 insertions(+)

diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
index 853dbc1b00d7..b448324527d8 100755
--- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
+++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
@@ -34,6 +34,7 @@ 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() {
@@ -611,6 +612,126 @@ 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 "${srv_ip}/24" dev s1
+	ip netns exec server ip link set s1 up
+
+	# Probe: check if kernel supports sctp flow key.
+	ovs_add_flow "$t" sctp4 \
+	    'in_port(1),eth(),eth_type(0x0800),ipv4(proto=132),sctp(dst=4443)' \
+	    '2' &>/dev/null
+	if [ $? -ne 0 ]; then
+		info "no support for sctp key - skipping"
+		ovs_exit_sig
+		return $ksft_skip
+	fi
+	ovs_del_flows "$t" sctp4
+
+	# 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
+
+	ovs_netns_spawn_daemon "$t" "server" \
+	    socat -u SCTP4-LISTEN:4443 STDOUT
+	local server_pid="$pid"
+	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 "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0806),arp()' \
+	    '1' || return 1
+
+	kill -TERM "$server_pid" 2>/dev/null
+	local i=0
+	while kill -0 "$server_pid" 2>/dev/null && [ "$i" -lt 5 ]; do
+	    sleep 0.2
+	    i=$((i + 1))
+	done
+	ovs_netns_spawn_daemon "$t" "server" \
+	    socat -u SCTP4-LISTEN:4443 STDOUT
+	server_pid="$pid"
+	ovs_wait sctp_eps_has server 4443 || return 1
+
+	ovs_sbx "$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 "$t" sctp4 \
+	    'in_port(2),eth(),eth_type(0x0800),ipv4(proto=132),sctp(src=4443)' \
+	    '1' || return 1
+
+	kill -TERM "$server_pid" 2>/dev/null
+	i=0
+	while kill -0 "$server_pid" 2>/dev/null && [ "$i" -lt 5 ]; do
+	    sleep 0.2
+	    i=$((i + 1))
+	done
+	ovs_netns_spawn_daemon "$t" "server" \
+	    socat -u SCTP4-LISTEN:4443 STDOUT
+	server_pid="$pid"
+	ovs_wait sctp_eps_has server 4443 || return 1
+
+	ovs_sbx "$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() {
-- 
2.55.0