Re: [PATCH net-next 12/12] selftests: net: selftest for ipvlan-macnat mode

[Paolo Abeni <pabeni@redhat.com>]

On 11/20/25 6:49 PM, Dmitry Skorodumov wrote:
> diff --git a/tools/testing/selftests/net/ipvtap_macnat_bridge.py b/tools/testing/selftests/net/ipvtap_macnat_bridge.py
> new file mode 100755
> index 000000000000..7dc4a626e5bb
> --- /dev/null
> +++ b/tools/testing/selftests/net/ipvtap_macnat_bridge.py
[...]
> +    TAP = sys.argv[1]
> +    IPVTAP = sys.argv[2]
> +
> +    print(f"Starting TAP bridge between {TAP} and {IPVTAP} in {ns_name}")
> +    bridge = TapBridge(TAP, IPVTAP)
> +    bridge.run()

This is not a complete review, but you need to add CONFIG_IPVTAP and
CONFIG_TAP to tools/testing/selftests/net/config.

> diff --git a/tools/testing/selftests/net/ipvtap_macnat_test.sh b/tools/testing/selftests/net/ipvtap_macnat_test.sh
> new file mode 100755
> index 000000000000..927d75af776b
> --- /dev/null
> +++ b/tools/testing/selftests/net/ipvtap_macnat_test.sh
> @@ -0,0 +1,333 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Tests for ipvtap in macnat mode
> +
> +NS_TST0=ipvlan-tst-0
> +NS_TST1=ipvlan-tst-1
> +NS_PHY=ipvlan-tst-phy

Please use lib.sh / setup_ns instead, to avoid netns name conflicts and
leverage automatic cleanup

> +
> +IP_HOST=172.25.0.1
> +IP_PHY=172.25.0.2
> +IP_TST0=172.25.0.10
> +IP_TST1=172.25.0.30
> +
> +IP_OK0=("172.25.0.10" "172.25.0.11" "172.25.0.12" "172.25.0.13")
> +IP6_OK0=("fc00::10" "fc00::11" "fc00::12" "fc00::13" )
> +
> +IP_OVFL0="172.25.0.14"
> +IP6_OVFL0="fc00::14"
> +
> +IP6_HOST=fc00::1
> +IP6_PHY=fc00::2
> +IP6_TST0=fc00::10
> +IP6_TST1=fc00::30
> +
> +MAC_HOST="92:3a:00:00:00:01"
> +MAC_PHY="92:3a:00:00:00:02"
> +MAC_TST0="92:3a:00:00:00:10"
> +MAC_TST1="92:3a:00:00:00:30"
> +
> +VETH_HOST=vethtst
> +VETH_PHY=vethtst.p
> +
> +#
> +# The testing environment looks this way:
> +#
> +# |------HOST------|     |------PHY-------|
> +# |      veth<----------------->veth      |
> +# |------|--|------|     |----------------|
> +#        |  |
> +#        |  |            |-----TST0-------|
> +#        |  |------------|----ipvtap      |
> +#        |               |----------------|
> +#        |
> +#        |               |-----TST1-------|
> +#        |---------------|----ivtap       |
> +#                        |----------------|
> +#
> +# The macnat mode is for virtual machines, so ipvtap-interface is supposed
> +# to be used only for traffic monitoring and doesn't have ip-address.
> +#
> +# To simulate a virtual machine on ipvtap, we create TAP-interfaces
> +# in TST environments and assing IP-addresses to them.
> +# TAP and IPVTAP are connected with simple python script.
> +#
> +
> +ns_run() {
> +	ns=$1
> +	shift
> +	if [[ "$ns" == "default" ]]; then
> +		"$@" >/dev/null
> +	else
> +		ip netns exec "$ns" "$@" >/dev/null
> +	fi
> +}
> +
> +configure_ns() {
> +	local ns=$1
> +	local n=$2
> +	local ip=$3
> +	local ip6=$4
> +	local mac=$5
> +
> +	ns_run "$ns" ip link set lo up
> +
> +	if ! ip link add netns "$ns" name "ipvtap0.$n" link $VETH_HOST \
> +	    type ipvtap mode l2macnat bridge; then
> +		exit_error "FAIL: Failed to configure ipvtap link."
> +	fi
> +	ns_run "$ns" ip link set "ipvtap0.$n" up
> +
> +	ns_run "$ns" ip tuntap add mode tap "tap0.$n"
> +	ns_run "$ns" ip link set dev "tap0.$n" address "$mac"
> +	# disable dad
> +	ns_run "$ns" sysctl -w "net/ipv6/conf/tap0.$n/accept_dad"=0
> +	ns_run "$ns" ip link set "tap0.$n" up
> +	ns_run "$ns" ip a a "$ip/24" dev "tap0.$n"
> +	ns_run "$ns" ip a a "$ip6/64" dev "tap0.$n"
> +}
> +
> +start_macnat_bridge() {
> +	local ns=$1
> +	local n=$2
> +	ip netns exec "$ns" python3 ipvtap_macnat_bridge.py \
> +		"tap0.$n" "ipvtap0.$n" &
> +}
> +
> +configure_veth() {
> +	local ns=$1
> +	local veth=$2
> +	local ip=$3
> +	local ip6=$4
> +	local mac=$5
> +
> +	ns_run "$ns" ip link set lo up
> +	ns_run "$ns" ethtool -K "$veth" tx off rx off
> +	ns_run "$ns" ip link set dev "$veth" address "$mac"
> +	ns_run "$ns" ip link set "$veth" up
> +	ns_run "$ns" ip a a "$ip/24" dev "$veth"
> +	ns_run "$ns" ip a a "$ip6/64" dev "$veth"
> +}
> +
> +setup_env() {
> +	ip netns add $NS_TST0
> +	ip netns add $NS_TST1
> +	ip netns add $NS_PHY
> +
> +	# setup simulated other-host (phy) and host itself
> +	ip link add $VETH_HOST type veth peer name $VETH_PHY \
> +	    netns $NS_PHY >/dev/null
> +
> +	# host config
> +	configure_veth default $VETH_HOST $IP_HOST $IP6_HOST $MAC_HOST
> +	configure_veth $NS_PHY $VETH_PHY $IP_PHY $IP6_PHY $MAC_PHY
> +
> +	# TST namespaces config
> +	configure_ns $NS_TST0 0 $IP_TST0 $IP6_TST0 $MAC_TST0
> +	configure_ns $NS_TST1 1 $IP_TST1 $IP6_TST1 $MAC_TST1
> +}
> +
> +ping_all() {
> +	# This will learn MAC/IP addresses on ipvtap
> +	local ns=$1
> +
> +	ns_run "$ns" ping -c 1 $IP_TST0
> +	ns_run "$ns" ping -c 1 $IP6_TST0
> +
> +	ns_run "$ns" ping -c 1 $IP_TST1
> +	ns_run "$ns" ping -c 1 $IP6_TST1
> +
> +	ns_run "$ns" ping -c 1 $IP_HOST
> +	ns_run "$ns" ping -c 1 $IP6_HOST
> +
> +	ns_run "$ns" ping -c 1 $IP_PHY
> +	ns_run "$ns" ping -c 1 $IP6_PHY
> +}
> +
> +check_mac_eq() {
> +	# Ensure IP corresponds to MAC.
> +	local ns=$1
> +	local ip=$2
> +	local mac=$3
> +	local dev=$4
> +
> +	if [[ "$ns" == "default" ]]; then
> +		out=$(
> +			ip neigh show "$ip" dev "$dev" \
> +			| grep "$ip" \
> +			| grep "$mac"
> +		)
> +	else
> +		out=$(
> +			ip netns exec "$ns" \
> +			ip neigh show "$ip" dev "$dev" \
> +			| grep "$ip" \
> +			| grep "$mac"
> +		)
> +	fi
> +
> +	if [[ $out'X' == "X" ]]; then
> +		exit_error "FAIL: '$ip' is not '$mac'"
> +	fi
> +}
> +
> +cleanup_env() {
> +	ip link del $VETH_HOST
> +	ip netns del $NS_TST0
> +	ip netns del $NS_TST1
> +	ip netns del $NS_PHY
> +}
> +
> +exit_error() {
> +	echo "$1"
> +	exit 1

It would be better to try to run all the test-cases and return a single
fail/success code. lib.sh can help with that. too.

/P