[PATCH net-next v2 2/2] selftests: openvswitch: add pop_vlan test
From: Minxi Hou
Date: Fri May 01 2026 - 09:40:55 EST
Add a test for the OVS datapath POP_VLAN action. The test uses
the VLAN sub-interface of a veth pair to generate 802.1Q tagged
frames and verifies that pop_vlan correctly strips the VLAN tag
before delivery via pcap frame capture.
The test has two verifications:
- Negative: forward tagged frames without pop_vlan, verify the
VLAN tag is still present on the egress interface.
- Positive: apply pop_vlan, verify the tag is removed and an
untagged ICMP echo request arrives at the egress interface.
Static ARP entries avoid the complexity of VLAN-tagged ARP
resolution (the egress side has no VLAN sub-interface and cannot
process tagged ARP).
Signed-off-by: Minxi Hou <houminxi@xxxxxxxxx>
---
v1 -> v2: rebase to latest net-next/main, drop --base=auto
.../selftests/net/openvswitch/openvswitch.sh | 132 ++++++++++++++++++
1 file changed, 132 insertions(+)
diff --git a/tools/testing/selftests/net/openvswitch/openvswitch.sh b/tools/testing/selftests/net/openvswitch/openvswitch.sh
index b327d3061ed5..cd614ff7b740 100755
--- a/tools/testing/selftests/net/openvswitch/openvswitch.sh
+++ b/tools/testing/selftests/net/openvswitch/openvswitch.sh
@@ -27,6 +27,7 @@ tests="
upcall_interfaces ovs: test the upcall interfaces
tunnel_metadata ovs: test extraction of tunnel metadata
drop_reason drop: test drop reasons are emitted
+ pop_vlan vlan-pop: POP_VLAN action strips 802.1Q tag
psample psample: Sampling packets with psample"
info() {
@@ -830,6 +831,137 @@ test_tunnel_metadata() {
return 0
}
+test_pop_vlan() {
+ modprobe -q openvswitch 2>/dev/null || true
+ [ -d /sys/module/openvswitch ] || return $ksft_skip
+ ip netns add __test_pop_vlan_netns__ 2>/dev/null || \
+ { info "CONFIG_NET_NS missing"; return $ksft_skip; }
+ ip netns del __test_pop_vlan_netns__ 2>/dev/null
+ modprobe -q 8021q 2>/dev/null || true
+ [ -d /sys/module/8021q ] || { info "CONFIG_VLAN_8021Q missing"; return $ksft_skip; }
+
+ local sbx="test_pop_vlan"
+ sbx_add "$sbx" || return $ksft_skip
+ ovs_add_dp "$sbx" vlandp || return 1
+
+ # --- baseline: untagged forwarding ---
+ ovs_add_netns_and_veths "$sbx" vlandp ns1 veth1 ns1veth 192.0.2.1/24 || return 1
+ ovs_add_netns_and_veths "$sbx" vlandp ns2 veth2 ns2veth 192.0.2.2/24 || return 1
+
+ # ARP + IPv4 bidirectional (all untagged)
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(1),eth(),eth_type(0x0806),arp()' '2' || return 1
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(2),eth(),eth_type(0x0806),arp()' '1' || return 1
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(1),eth(),eth_type(0x0800),ipv4()' '2' || return 1
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(2),eth(),eth_type(0x0800),ipv4()' '1' || return 1
+ ip netns exec ns1 ping -c 3 -W 2 192.0.2.2 || return 1
+
+ # --- POP_VLAN test ---
+ # Register cleanup before creating resources (safe on failure paths)
+ on_exit "ip -n ns1 link del ns1veth.10 2>/dev/null || true
+ ip -n ns2 addr del 198.51.100.2/24 dev ns2veth 2>/dev/null || true"
+
+ # ns1: VLAN sub-interface generates tagged frames
+ ip -n ns1 link add link ns1veth name ns1veth.10 type vlan id 10
+ ip -n ns1 addr add 198.51.100.1/24 dev ns1veth.10
+ ip -n ns1 link set ns1veth.10 up
+
+ # ns2: no VLAN sub-interface. POP delivers untagged frames to ns2veth
+ ip -n ns2 addr add 198.51.100.2/24 dev ns2veth
+
+ # veth disable VLAN offload + GRO (ensure kernel software tag processing)
+ if command -v ethtool >/dev/null 2>&1; then
+ ip netns exec ns1 ethtool -k ns1veth 2>/dev/null | grep -q vlan-offload && \
+ ip netns exec ns1 ethtool -K ns1veth rx-vlan-offload off \
+ tx-vlan-offload off gro off 2>/dev/null || true
+ ip netns exec ns2 ethtool -k ns2veth 2>/dev/null | grep -q vlan-offload && \
+ ip netns exec ns2 ethtool -K ns2veth rx-vlan-offload off \
+ tx-vlan-offload off gro off 2>/dev/null || true
+ fi
+
+ ovs_del_flows "$sbx" vlandp
+
+ # Static ARP avoids VLAN-tagged ARP complexity (ns2 has no VLAN
+ # sub-interface, so tagged ARP would be invisible to ns2).
+ local ns1veth10mac ns2mac
+ ns1veth10mac=$(ip -n ns1 link show ns1veth.10 | \
+ awk '/link\/ether/ {print $2}')
+ ns2mac=$(ip -n ns2 link show ns2veth | \
+ awk '/link\/ether/ {print $2}')
+ [ -n "$ns1veth10mac" ] && echo "$ns1veth10mac" | \
+ grep -qE "^([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}$" || return 1
+ [ -n "$ns2mac" ] && echo "$ns2mac" | \
+ grep -qE "^([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}$" || return 1
+ ip -n ns1 neigh replace 198.51.100.2 lladdr "$ns2mac" \
+ dev ns1veth.10 nud permanent || return 1
+ ip -n ns2 neigh replace 198.51.100.1 lladdr "$ns1veth10mac" \
+ dev ns2veth nud permanent || return 1
+
+ # --- Negative check: fwd without pop_vlan, VLAN tag stays ---
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(1),eth(),eth_type(0x8100),vlan(vid=10),encap(eth_type(0x0800),ipv4(src=198.51.100.1,proto=1),icmp())' \
+ '2' || return 1
+
+ local pcap_no_pop
+ pcap_no_pop=$(mktemp --suffix=.pcap)
+ on_exit "rm -f $pcap_no_pop"
+ ip netns exec ns2 tcpdump -nei ns2veth -w "$pcap_no_pop" -U &
+ local tpid_no_pop=$!
+ on_exit "kill $tpid_no_pop 2>/dev/null || true"
+ sleep $((WAIT_TIMEOUT / 5 < 2 ? 2 : WAIT_TIMEOUT / 5))
+
+ ip netns exec ns1 ping -I ns1veth.10 -c 3 -W 1 198.51.100.2 \
+ >/dev/null 2>&1 || true
+ kill $tpid_no_pop 2>/dev/null || true; wait $tpid_no_pop 2>/dev/null || true
+
+ # assert: VLAN tag still present (no pop_vlan in action)
+ tcpdump -nr "$pcap_no_pop" 'vlan' 2>/dev/null | grep -q . || {
+ info "FAIL: negative check: no VLAN tag (expected tag present)"; return 1
+ }
+
+ ovs_del_flows "$sbx" vlandp
+
+ # --- Positive: pop_vlan strips tag ---
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(1),eth(),eth_type(0x8100),vlan(vid=10),encap(eth_type(0x0800),ipv4(src=198.51.100.1,proto=1),icmp())' \
+ 'pop_vlan,2' || return 1
+ ovs_add_flow "$sbx" vlandp \
+ 'in_port(2),eth(),eth_type(0x0800),ipv4()' '1' || return 1
+
+ local pcap
+ pcap=$(mktemp --suffix=.pcap)
+ on_exit "rm -f $pcap"
+ ip netns exec ns2 tcpdump -nei ns2veth -w "$pcap" -U &
+ local tpid=$!
+ on_exit "kill $tpid 2>/dev/null || true"
+ sleep $((WAIT_TIMEOUT / 5 < 2 ? 2 : WAIT_TIMEOUT / 5))
+
+ # ping reply unreachable: ns1veth.10 only accepts tagged frames,
+ # ns2 sends untagged reply -> dropped by ns1veth.10.
+ local ping_rc=0
+ ip netns exec ns1 ping -I ns1veth.10 -c 3 -W 1 198.51.100.2 \
+ >/dev/null 2>&1 || ping_rc=$?
+ kill $tpid 2>/dev/null || true; wait $tpid 2>/dev/null || true
+
+ # ping failure is expected (reply path asymmetric)
+ [ "$ping_rc" -ne 0 ] || \
+ info "NOTE: ping succeeded unexpectedly (reply reached ns1veth.10)"
+
+ # assert: no VLAN tag (POP succeeded), untagged ICMP echo request arrived
+ tcpdump -nr "$pcap" 'vlan' 2>/dev/null | grep -q . && {
+ info "FAIL: POP_VLAN: VLAN tag still present"; return 1
+ }
+ tcpdump -nr "$pcap" 'icmp and icmp[icmptype]=8' \
+ 2>/dev/null | grep -q . || {
+ info "FAIL: POP_VLAN: no untagged ICMP echo request"; return 1
+ }
+
+ return 0
+}
+
run_test() {
(
tname="$1"
--
2.53.0