selftests: add a selftest for directed broadcast forwarding

As Ido's suggestion, this patch is to add a selftest for directed
broadcast forwarding with vrf. It does the assertion by checking
the src IP of the echo-reply packet in ping_test_from.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/router_broadcast.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+ALL_TESTS="ping_ipv4"
+NUM_NETIFS=6
+source lib.sh
+
+h1_create()
+{
+	vrf_create "vrf-h1"
+	ip link set dev $h1 master vrf-h1
+
+	ip link set dev vrf-h1 up
+	ip link set dev $h1 up
+
+	ip address add 192.0.2.2/24 dev $h1
+
+	ip route add 198.51.100.0/24 vrf vrf-h1 nexthop via 192.0.2.1
+	ip route add 198.51.200.0/24 vrf vrf-h1 nexthop via 192.0.2.1
+}
+
+h1_destroy()
+{
+	ip route del 198.51.200.0/24 vrf vrf-h1
+	ip route del 198.51.100.0/24 vrf vrf-h1
+
+	ip address del 192.0.2.2/24 dev $h1
+
+	ip link set dev $h1 down
+	vrf_destroy "vrf-h1"
+}
+
+h2_create()
+{
+	vrf_create "vrf-h2"
+	ip link set dev $h2 master vrf-h2
+
+	ip link set dev vrf-h2 up
+	ip link set dev $h2 up
+
+	ip address add 198.51.100.2/24 dev $h2
+
+	ip route add 192.0.2.0/24 vrf vrf-h2 nexthop via 198.51.100.1
+	ip route add 198.51.200.0/24 vrf vrf-h2 nexthop via 198.51.100.1
+}
+
+h2_destroy()
+{
+	ip route del 198.51.200.0/24 vrf vrf-h2
+	ip route del 192.0.2.0/24 vrf vrf-h2
+
+	ip address del 198.51.100.2/24 dev $h2
+
+	ip link set dev $h2 down
+	vrf_destroy "vrf-h2"
+}
+
+h3_create()
+{
+	vrf_create "vrf-h3"
+	ip link set dev $h3 master vrf-h3
+
+	ip link set dev vrf-h3 up
+	ip link set dev $h3 up
+
+	ip address add 198.51.200.2/24 dev $h3
+
+	ip route add 192.0.2.0/24 vrf vrf-h3 nexthop via 198.51.200.1
+	ip route add 198.51.100.0/24 vrf vrf-h3 nexthop via 198.51.200.1
+}
+
+h3_destroy()
+{
+	ip route del 198.51.100.0/24 vrf vrf-h3
+	ip route del 192.0.2.0/24 vrf vrf-h3
+
+	ip address del 198.51.200.2/24 dev $h3
+
+	ip link set dev $h3 down
+	vrf_destroy "vrf-h3"
+}
+
+router_create()
+{
+	ip link set dev $rp1 up
+	ip link set dev $rp2 up
+	ip link set dev $rp3 up
+
+	ip address add 192.0.2.1/24 dev $rp1
+
+	ip address add 198.51.100.1/24 dev $rp2
+	ip address add 198.51.200.1/24 dev $rp3
+}
+
+router_destroy()
+{
+	ip address del 198.51.200.1/24 dev $rp3
+	ip address del 198.51.100.1/24 dev $rp2
+
+	ip address del 192.0.2.1/24 dev $rp1
+
+	ip link set dev $rp3 down
+	ip link set dev $rp2 down
+	ip link set dev $rp1 down
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	rp1=${NETIFS[p2]}
+
+	rp2=${NETIFS[p3]}
+	h2=${NETIFS[p4]}
+
+	rp3=${NETIFS[p5]}
+	h3=${NETIFS[p6]}
+
+	vrf_prepare
+
+	h1_create
+	h2_create
+	h3_create
+
+	router_create
+
+	forwarding_enable
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	forwarding_restore
+
+	router_destroy
+
+	h3_destroy
+	h2_destroy
+	h1_destroy
+
+	vrf_cleanup
+}
+
+bc_forwarding_disable()
+{
+	sysctl_set net.ipv4.conf.all.bc_forwarding 0
+	sysctl_set net.ipv4.conf.$rp1.bc_forwarding 0
+}
+
+bc_forwarding_enable()
+{
+	sysctl_set net.ipv4.conf.all.bc_forwarding 1
+	sysctl_set net.ipv4.conf.$rp1.bc_forwarding 1
+}
+
+bc_forwarding_restore()
+{
+	sysctl_restore net.ipv4.conf.$rp1.bc_forwarding
+	sysctl_restore net.ipv4.conf.all.bc_forwarding
+}
+
+ping_test_from()
+{
+	local oif=$1
+	local dip=$2
+	local from=$3
+	local fail=${4:-0}
+
+	RET=0
+
+	log_info "ping $dip, expected reply from $from"
+	ip vrf exec $(master_name_get $oif) \
+	$PING -I $oif $dip -c 10 -i 0.1 -w 2 -b 2>&1 | grep $from &> /dev/null
+	check_err_fail $fail $?
+}
+
+ping_ipv4()
+{
+	sysctl_set net.ipv4.icmp_echo_ignore_broadcasts 0
+
+	bc_forwarding_disable
+	log_info "bc_forwarding disabled on r1 =>"
+	ping_test_from $h1 198.51.100.255 192.0.2.1
+	log_test "h1 -> net2: reply from r1 (not forwarding)"
+	ping_test_from $h1 198.51.200.255 192.0.2.1
+	log_test "h1 -> net3: reply from r1 (not forwarding)"
+	ping_test_from $h1 192.0.2.255 192.0.2.1
+	log_test "h1 -> net1: reply from r1 (not dropping)"
+	ping_test_from $h1 255.255.255.255 192.0.2.1
+	log_test "h1 -> 255.255.255.255: reply from r1 (not forwarding)"
+
+	ping_test_from $h2 192.0.2.255 198.51.100.1
+	log_test "h2 -> net1: reply from r1 (not forwarding)"
+	ping_test_from $h2 198.51.200.255 198.51.100.1
+	log_test "h2 -> net3: reply from r1 (not forwarding)"
+	ping_test_from $h2 198.51.100.255 198.51.100.1
+	log_test "h2 -> net2: reply from r1 (not dropping)"
+	ping_test_from $h2 255.255.255.255 198.51.100.1
+	log_test "h2 -> 255.255.255.255: reply from r1 (not forwarding)"
+	bc_forwarding_restore
+
+	bc_forwarding_enable
+	log_info "bc_forwarding enabled on r1 =>"
+	ping_test_from $h1 198.51.100.255 198.51.100.2
+	log_test "h1 -> net2: reply from h2 (forwarding)"
+	ping_test_from $h1 198.51.200.255 198.51.200.2
+	log_test "h1 -> net3: reply from h3 (forwarding)"
+	ping_test_from $h1 192.0.2.255 192.0.2.1 1
+	log_test "h1 -> net1: no reply (dropping)"
+	ping_test_from $h1 255.255.255.255 192.0.2.1
+	log_test "h1 -> 255.255.255.255: reply from r1 (not forwarding)"
+
+	ping_test_from $h2 192.0.2.255 192.0.2.2
+	log_test "h2 -> net1: reply from h1 (forwarding)"
+	ping_test_from $h2 198.51.200.255 198.51.200.2
+	log_test "h2 -> net3: reply from h3 (forwarding)"
+	ping_test_from $h2 198.51.100.255 198.51.100.1 1
+	log_test "h2 -> net2: no reply (dropping)"
+	ping_test_from $h2 255.255.255.255 198.51.100.1
+	log_test "h2 -> 255.255.255.255: reply from r1 (not forwarding)"
+	bc_forwarding_restore
+
+	sysctl_restore net.ipv4.icmp_echo_ignore_broadcasts
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS