selftests/net: test nexthop without gw

This test implement the scenario described in the commit
"ip: fix dflt addr selection for connected nexthop".
The test configures a nexthop object with an output device only (no gateway
address) and a route that uses this nexthop. The goal is to check if the
kernel selects a valid source address.

Link: https://lore.kernel.org/netdev/[email protected]/
Signed-off-by: Nicolas Dichtel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: NicolasDichtel

tools/testing/selftests/net/Makefile

@@ -11,7 +11,7 @@ TEST_PROGS += udpgso_bench.sh fib_rule_tests.sh msg_zerocopy.sh psock_snd.sh
 TEST_PROGS += udpgro_bench.sh udpgro.sh test_vxlan_under_vrf.sh reuseport_addr_any.sh
 TEST_PROGS += test_vxlan_fdb_changelink.sh so_txtime.sh ipv6_flowlabel.sh
 TEST_PROGS += tcp_fastopen_backup_key.sh fcnal-test.sh l2tp.sh traceroute.sh
-TEST_PROGS += fin_ack_lat.sh fib_nexthop_multiprefix.sh fib_nexthops.sh
+TEST_PROGS += fin_ack_lat.sh fib_nexthop_multiprefix.sh fib_nexthops.sh fib_nexthop_nongw.sh
 TEST_PROGS += altnames.sh icmp.sh icmp_redirect.sh ip6_gre_headroom.sh
 TEST_PROGS += route_localnet.sh
 TEST_PROGS += reuseaddr_ports_exhausted.sh

tools/testing/selftests/net/fib_nexthop_nongw.sh

@@ -0,0 +1,119 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# ns: h1               | ns: h2
+#   192.168.0.1/24     |
+#            eth0      |
+#                      |       192.168.1.1/32
+#            veth0 <---|---> veth1
+# Validate source address selection for route without gateway
+
+PAUSE_ON_FAIL=no
+VERBOSE=0
+ret=0
+
+################################################################################
+# helpers
+
+log_test()
+{
+	local rc=$1
+	local expected=$2
+	local msg="$3"
+
+	if [ ${rc} -eq ${expected} ]; then
+		printf "TEST: %-60s  [ OK ]\n" "${msg}"
+		nsuccess=$((nsuccess+1))
+	else
+		ret=1
+		nfail=$((nfail+1))
+		printf "TEST: %-60s  [FAIL]\n" "${msg}"
+		if [ "${PAUSE_ON_FAIL}" = "yes" ]; then
+			echo
+			echo "hit enter to continue, 'q' to quit"
+			read a
+			[ "$a" = "q" ] && exit 1
+		fi
+	fi
+
+	[ "$VERBOSE" = "1" ] && echo
+}
+
+run_cmd()
+{
+	local cmd="$*"
+	local out
+	local rc
+
+	if [ "$VERBOSE" = "1" ]; then
+		echo "COMMAND: $cmd"
+	fi
+
+	out=$(eval $cmd 2>&1)
+	rc=$?
+	if [ "$VERBOSE" = "1" -a -n "$out" ]; then
+		echo "$out"
+	fi
+
+	[ "$VERBOSE" = "1" ] && echo
+
+	return $rc
+}
+
+################################################################################
+# config
+setup()
+{
+	ip netns add h1
+	ip -n h1 link set lo up
+	ip netns add h2
+	ip -n h2 link set lo up
+
+	# Add a fake eth0 to support an ip address
+	ip -n h1 link add name eth0 type dummy
+	ip -n h1 link set eth0 up
+	ip -n h1 address add 192.168.0.1/24 dev eth0
+
+	# Configure veths (same @mac, arp off)
+	ip -n h1 link add name veth0 type veth peer name veth1 netns h2
+	ip -n h1 link set veth0 up
+
+	ip -n h2 link set veth1 up
+
+	# Configure @IP in the peer netns
+	ip -n h2 address add 192.168.1.1/32 dev veth1
+	ip -n h2 route add default dev veth1
+
+	# Add a nexthop without @gw and use it in a route
+	ip -n h1 nexthop add id 1 dev veth0
+	ip -n h1 route add 192.168.1.1 nhid 1
+}
+
+cleanup()
+{
+	ip netns del h1 2>/dev/null
+	ip netns del h2 2>/dev/null
+}
+
+trap cleanup EXIT
+
+################################################################################
+# main
+
+while getopts :pv o
+do
+	case $o in
+		p) PAUSE_ON_FAIL=yes;;
+		v) VERBOSE=1;;
+	esac
+done
+
+cleanup
+setup
+
+run_cmd ip -netns h1 route get 192.168.1.1
+log_test $? 0 "nexthop: get route with nexthop without gw"
+run_cmd ip netns exec h1 ping -c1 192.168.1.1
+log_test $? 0 "nexthop: ping through nexthop without gw"
+
+exit $ret