selftests: net: Add a selftest for VXLAN with FDB nexthop groups

Add test cases for VXLAN with FDB nexthop groups, testing both IPv4 and
IPv6. Test basic Tx functionality as well as some corner cases.

Example output:

# ./test_vxlan_nh.sh
TEST: VXLAN FDB nexthop: IPv4 basic Tx [ OK ]
TEST: VXLAN FDB nexthop: IPv6 basic Tx [ OK ]
TEST: VXLAN FDB nexthop: learning [ OK ]
TEST: VXLAN FDB nexthop: IPv4 proxy [ OK ]
TEST: VXLAN FDB nexthop: IPv6 proxy [ OK ]

Signed-off-by: Ido Schimmel <[e-mail]>
Reviewed-by: Nikolay Aleksandrov <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/Makefile

···
 TEST_GEN_PROGS += bind_timewait
 TEST_PROGS += test_vxlan_mdb.sh
 TEST_PROGS += test_bridge_neigh_suppress.sh
+TEST_PROGS += test_vxlan_nh.sh
 TEST_PROGS += test_vxlan_nolocalbypass.sh
 TEST_PROGS += test_bridge_backup_port.sh
 TEST_PROGS += test_neigh.sh

tools/testing/selftests/net/test_vxlan_nh.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source lib.sh
+TESTS="
+	basic_tx_ipv4
+	basic_tx_ipv6
+	learning
+	proxy_ipv4
+	proxy_ipv6
+"
+VERBOSE=0
+
+################################################################################
+# Utilities
+
+run_cmd()
+{
+	local cmd="$1"
+	local out
+	local stderr="2>/dev/null"
+
+	if [ "$VERBOSE" = "1" ]; then
+		echo "COMMAND: $cmd"
+		stderr=
+	fi
+
+	out=$(eval "$cmd" "$stderr")
+	rc=$?
+	if [ "$VERBOSE" -eq 1 ] && [ -n "$out" ]; then
+		echo "    $out"
+	fi
+
+	return $rc
+}
+
+################################################################################
+# Cleanup
+
+exit_cleanup_all()
+{
+	cleanup_all_ns
+	exit "${EXIT_STATUS}"
+}
+
+################################################################################
+# Tests
+
+nh_stats_get()
+{
+	ip -n "$ns1" -s -j nexthop show id 10 | jq ".[][\"group_stats\"][][\"packets\"]"
+}
+
+tc_stats_get()
+{
+	tc_rule_handle_stats_get "dev dummy1 egress" 101 ".packets" "-n $ns1"
+}
+
+basic_tx_common()
+{
+	local af_str=$1; shift
+	local proto=$1; shift
+	local local_addr=$1; shift
+	local plen=$1; shift
+	local remote_addr=$1; shift
+
+	RET=0
+
+	# Test basic Tx functionality. Check that stats are incremented on
+	# both the FDB nexthop group and the egress device.
+
+	run_cmd "ip -n $ns1 link add name dummy1 up type dummy"
+	run_cmd "ip -n $ns1 route add $remote_addr/$plen dev dummy1"
+	run_cmd "tc -n $ns1 qdisc add dev dummy1 clsact"
+	run_cmd "tc -n $ns1 filter add dev dummy1 egress proto $proto pref 1 handle 101 flower ip_proto udp dst_ip $remote_addr dst_port 4789 action pass"
+
+	run_cmd "ip -n $ns1 address add $local_addr/$plen dev lo"
+
+	run_cmd "ip -n $ns1 nexthop add id 1 via $remote_addr fdb"
+	run_cmd "ip -n $ns1 nexthop add id 10 group 1 fdb"
+
+	run_cmd "ip -n $ns1 link add name vx0 up type vxlan id 10010 local $local_addr dstport 4789"
+	run_cmd "bridge -n $ns1 fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10"
+
+	run_cmd "ip netns exec $ns1 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 1 -q"
+
+	busywait "$BUSYWAIT_TIMEOUT" until_counter_is "== 1" nh_stats_get > /dev/null
+	check_err $? "FDB nexthop group stats did not increase"
+
+	busywait "$BUSYWAIT_TIMEOUT" until_counter_is "== 1" tc_stats_get > /dev/null
+	check_err $? "tc filter stats did not increase"
+
+	log_test "VXLAN FDB nexthop: $af_str basic Tx"
+}
+
+basic_tx_ipv4()
+{
+	basic_tx_common "IPv4" ipv4 192.0.2.1 32 192.0.2.2
+}
+
+basic_tx_ipv6()
+{
+	basic_tx_common "IPv6" ipv6 2001:db8:1::1 128 2001:db8:1::2
+}
+
+learning()
+{
+	RET=0
+
+	# When learning is enabled on the VXLAN device, an incoming packet
+	# might try to refresh an FDB entry that points to an FDB nexthop group
+	# instead of an ordinary remote destination. Check that the kernel does
+	# not crash in this situation.
+
+	run_cmd "ip -n $ns1 address add 192.0.2.1/32 dev lo"
+	run_cmd "ip -n $ns1 address add 192.0.2.2/32 dev lo"
+
+	run_cmd "ip -n $ns1 nexthop add id 1 via 192.0.2.3 fdb"
+	run_cmd "ip -n $ns1 nexthop add id 10 group 1 fdb"
+
+	run_cmd "ip -n $ns1 link add name vx0 up type vxlan id 10010 local 192.0.2.1 dstport 12345 localbypass"
+	run_cmd "ip -n $ns1 link add name vx1 up type vxlan id 10020 local 192.0.2.2 dstport 54321 learning"
+
+	run_cmd "bridge -n $ns1 fdb add 00:11:22:33:44:55 dev vx0 self static dst 192.0.2.2 port 54321 vni 10020"
+	run_cmd "bridge -n $ns1 fdb add 00:aa:bb:cc:dd:ee dev vx1 self static nhid 10"
+
+	run_cmd "ip netns exec $ns1 mausezahn vx0 -a 00:aa:bb:cc:dd:ee -b 00:11:22:33:44:55 -c 1 -q"
+
+	log_test "VXLAN FDB nexthop: learning"
+}
+
+proxy_common()
+{
+	local af_str=$1; shift
+	local local_addr=$1; shift
+	local plen=$1; shift
+	local remote_addr=$1; shift
+	local neigh_addr=$1; shift
+	local ping_cmd=$1; shift
+
+	RET=0
+
+	# When the "proxy" option is enabled on the VXLAN device, the device
+	# will suppress ARP requests and IPv6 Neighbor Solicitation messages if
+	# it is able to reply on behalf of the remote host. That is, if a
+	# matching and valid neighbor entry is configured on the VXLAN device
+	# whose MAC address is not behind the "any" remote (0.0.0.0 / ::). The
+	# FDB entry for the neighbor's MAC address might point to an FDB
+	# nexthop group instead of an ordinary remote destination. Check that
+	# the kernel does not crash in this situation.
+
+	run_cmd "ip -n $ns1 address add $local_addr/$plen dev lo"
+
+	run_cmd "ip -n $ns1 nexthop add id 1 via $remote_addr fdb"
+	run_cmd "ip -n $ns1 nexthop add id 10 group 1 fdb"
+
+	run_cmd "ip -n $ns1 link add name vx0 up type vxlan id 10010 local $local_addr dstport 4789 proxy"
+
+	run_cmd "ip -n $ns1 neigh add $neigh_addr lladdr 00:11:22:33:44:55 nud perm dev vx0"
+
+	run_cmd "bridge -n $ns1 fdb add 00:11:22:33:44:55 dev vx0 self static nhid 10"
+
+	run_cmd "ip netns exec $ns1 $ping_cmd"
+
+	log_test "VXLAN FDB nexthop: $af_str proxy"
+}
+
+proxy_ipv4()
+{
+	proxy_common "IPv4" 192.0.2.1 32 192.0.2.2 192.0.2.3 \
+		"arping -b -c 1 -s 192.0.2.1 -I vx0 192.0.2.3"
+}
+
+proxy_ipv6()
+{
+	proxy_common "IPv6" 2001:db8:1::1 128 2001:db8:1::2 2001:db8:1::3 \
+		"ndisc6 -r 1 -s 2001:db8:1::1 -w 1 2001:db8:1::3 vx0"
+}
+
+################################################################################
+# Usage
+
+usage()
+{
+	cat <<EOF
+usage: ${0##*/} OPTS
+
+        -t <test>   Test(s) to run (default: all)
+                    (options: $TESTS)
+        -p          Pause on fail
+        -v          Verbose mode (show commands and output)
+EOF
+}
+
+################################################################################
+# Main
+
+while getopts ":t:pvh" opt; do
+	case $opt in
+		t) TESTS=$OPTARG;;
+		p) PAUSE_ON_FAIL=yes;;
+		v) VERBOSE=$((VERBOSE + 1));;
+		h) usage; exit 0;;
+		*) usage; exit 1;;
+	esac
+done
+
+require_command mausezahn
+require_command arping
+require_command ndisc6
+require_command jq
+
+if ! ip nexthop help 2>&1 | grep -q "stats"; then
+	echo "SKIP: iproute2 ip too old, missing nexthop stats support"
+	exit "$ksft_skip"
+fi
+
+trap exit_cleanup_all EXIT
+
+for t in $TESTS
+do
+	setup_ns ns1; $t; cleanup_all_ns;
+done