tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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selftests: net: add macvlan multicast test for shared source MAC

Add a selftest that verifies multicast delivery to a macvlan bridge
port when the source MAC of the incoming frame matches the macvlan's
own MAC address.

This scenario occurs with protocols like VRRP where multiple hosts
share the same virtual MAC address. Without the corresponding kernel
change, macvlan bridge mode does not handle this case and the
multicast frame is not delivered.

Signed-off-by: Kibaek Yoo <psykibaek@gmail.com>
Link: https://patch.msgid.link/20260228071613.4360-2-psykibaek@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

authored by

Kibaek Yoo and committed by
Jakub Kicinski 4ad96a7c b52363f7

+94
+1
tools/testing/selftests/net/Makefile
··· 55 55 l2tp.sh \ 56 56 link_netns.py \ 57 57 lwt_dst_cache_ref_loop.sh \ 58 + macvlan_mcast_shared_mac.sh \ 58 59 msg_zerocopy.sh \ 59 60 nat6to4.sh \ 60 61 ndisc_unsolicited_na_test.sh \
+93
tools/testing/selftests/net/macvlan_mcast_shared_mac.sh
··· 1 + #!/bin/bash 2 + # SPDX-License-Identifier: GPL-2.0 3 + # 4 + # Test multicast delivery to macvlan bridge ports when the source MAC 5 + # matches the macvlan's own MAC address (e.g., VRRP virtual MAC shared 6 + # across multiple hosts). 7 + # 8 + # Topology: 9 + # 10 + # NS_SRC NS_BRIDGE 11 + # veth_src (SHARED_MAC) <-----> veth_dst 12 + # | 13 + # +-- macvlan0 (bridge mode, SHARED_MAC) 14 + # 15 + # A multicast packet sent from NS_SRC with source MAC equal to 16 + # macvlan0's MAC must still be delivered to macvlan0. 17 + 18 + source lib.sh 19 + 20 + SHARED_MAC="00:00:5e:00:01:01" 21 + MCAST_ADDR="239.0.0.1" 22 + 23 + setup() { 24 + setup_ns NS_SRC NS_BRIDGE 25 + 26 + ip -net "${NS_BRIDGE}" link add veth_dst type veth \ 27 + peer name veth_src netns "${NS_SRC}" 28 + 29 + ip -net "${NS_SRC}" link set veth_src address "${SHARED_MAC}" 30 + ip -net "${NS_SRC}" link set veth_src up 31 + ip -net "${NS_SRC}" addr add 192.168.1.1/24 dev veth_src 32 + 33 + ip -net "${NS_BRIDGE}" link set veth_dst up 34 + 35 + ip -net "${NS_BRIDGE}" link add macvlan0 link veth_dst \ 36 + type macvlan mode bridge 37 + ip -net "${NS_BRIDGE}" link set macvlan0 address "${SHARED_MAC}" 38 + ip -net "${NS_BRIDGE}" link set macvlan0 up 39 + ip -net "${NS_BRIDGE}" addr add 192.168.1.2/24 dev macvlan0 40 + 41 + # Accept all multicast so the mc_filter passes for any group. 42 + ip -net "${NS_BRIDGE}" link set macvlan0 allmulticast on 43 + } 44 + 45 + cleanup() { 46 + rm -f "${CAPFILE}" "${CAPOUT}" 47 + cleanup_ns "${NS_SRC}" "${NS_BRIDGE}" 48 + } 49 + 50 + test_macvlan_mcast_shared_mac() { 51 + CAPFILE=$(mktemp) 52 + CAPOUT=$(mktemp) 53 + 54 + echo "Testing multicast delivery to macvlan with shared source MAC" 55 + 56 + # Listen for one ICMP packet on macvlan0. 57 + timeout 5s ip netns exec "${NS_BRIDGE}" \ 58 + tcpdump -i macvlan0 -c 1 -w "${CAPFILE}" icmp &> "${CAPOUT}" & 59 + local pid=$! 60 + if ! slowwait 1 grep -qs "listening" "${CAPOUT}"; then 61 + echo "[FAIL] tcpdump did not start listening" 62 + return "${ksft_fail}" 63 + fi 64 + 65 + # Send multicast ping from NS_SRC; source MAC equals macvlan0's MAC. 66 + ip netns exec "${NS_SRC}" \ 67 + ping -W 0.1 -c 3 -I veth_src "${MCAST_ADDR}" &> /dev/null 68 + 69 + wait "${pid}" 70 + 71 + local count 72 + count=$(tcpdump -r "${CAPFILE}" 2>/dev/null | wc -l) 73 + if [[ "${count}" -ge 1 ]]; then 74 + echo "[ OK ]" 75 + return "${ksft_pass}" 76 + else 77 + echo "[FAIL] expected at least 1 ICMP packet on macvlan0," \ 78 + "got ${count}" 79 + return "${ksft_fail}" 80 + fi 81 + } 82 + 83 + if [ ! -x "$(command -v tcpdump)" ]; then 84 + echo "SKIP: Could not run test without tcpdump tool" 85 + exit "${ksft_skip}" 86 + fi 87 + 88 + trap cleanup EXIT 89 + 90 + setup 91 + test_macvlan_mcast_shared_mac 92 + 93 + exit $?