selftests: fib_test: Add a test case for IPv4 broadcast neighbours

Test that resolved neighbours for IPv4 broadcast addresses are
unaffected by the configuration of matching broadcast routes, whereas
unresolved neighbours are invalidated.

Without previous patch:

 # ./fib_tests.sh -t ipv4_bcast_neigh

 IPv4 broadcast neighbour tests
     TEST: Resolved neighbour for broadcast address                      [ OK ]
     TEST: Resolved neighbour for network broadcast address              [ OK ]
     TEST: Unresolved neighbour for broadcast address                    [FAIL]
     TEST: Unresolved neighbour for network broadcast address            [FAIL]

 Tests passed:   2
 Tests failed:   2

With previous patch:

 # ./fib_tests.sh -t ipv4_bcast_neigh

 IPv4 broadcast neighbour tests
     TEST: Resolved neighbour for broadcast address                      [ OK ]
     TEST: Resolved neighbour for network broadcast address              [ OK ]
     TEST: Unresolved neighbour for broadcast address                    [ OK ]
     TEST: Unresolved neighbour for network broadcast address            [ OK ]

 Tests passed:   4
 Tests failed:   0
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/fib_tests.sh

@@ -9,7 +9,7 @@ ret=0
 ksft_skip=4
 
 # all tests in this script. Can be overridden with -t option
-TESTS="unregister down carrier nexthop suppress ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw rp_filter ipv4_del_addr ipv4_mangle ipv6_mangle"
+TESTS="unregister down carrier nexthop suppress ipv6_rt ipv4_rt ipv6_addr_metric ipv4_addr_metric ipv6_route_metrics ipv4_route_metrics ipv4_route_v6_gw rp_filter ipv4_del_addr ipv4_mangle ipv6_mangle ipv4_bcast_neigh"
 
 VERBOSE=0
 PAUSE_ON_FAIL=no
@@ -1954,6 +1954,61 @@ ipv6_mangle_test()
 	route_cleanup
 }
 
+ip_neigh_get_check()
+{
+	ip neigh help 2>&1 | grep -q 'ip neigh get'
+	if [ $? -ne 0 ]; then
+		echo "iproute2 command does not support neigh get. Skipping test"
+		return 1
+	fi
+
+	return 0
+}
+
+ipv4_bcast_neigh_test()
+{
+	local rc
+
+	echo
+	echo "IPv4 broadcast neighbour tests"
+
+	ip_neigh_get_check || return 1
+
+	setup
+
+	set -e
+	run_cmd "$IP neigh add 192.0.2.111 lladdr 00:11:22:33:44:55 nud perm dev dummy0"
+	run_cmd "$IP neigh add 192.0.2.255 lladdr 00:11:22:33:44:55 nud perm dev dummy0"
+
+	run_cmd "$IP neigh get 192.0.2.111 dev dummy0"
+	run_cmd "$IP neigh get 192.0.2.255 dev dummy0"
+
+	run_cmd "$IP address add 192.0.2.1/24 broadcast 192.0.2.111 dev dummy0"
+
+	run_cmd "$IP neigh add 203.0.113.111 nud failed dev dummy0"
+	run_cmd "$IP neigh add 203.0.113.255 nud failed dev dummy0"
+
+	run_cmd "$IP neigh get 203.0.113.111 dev dummy0"
+	run_cmd "$IP neigh get 203.0.113.255 dev dummy0"
+
+	run_cmd "$IP address add 203.0.113.1/24 broadcast 203.0.113.111 dev dummy0"
+	set +e
+
+	run_cmd "$IP neigh get 192.0.2.111 dev dummy0"
+	log_test $? 0 "Resolved neighbour for broadcast address"
+
+	run_cmd "$IP neigh get 192.0.2.255 dev dummy0"
+	log_test $? 0 "Resolved neighbour for network broadcast address"
+
+	run_cmd "$IP neigh get 203.0.113.111 dev dummy0"
+	log_test $? 2 "Unresolved neighbour for broadcast address"
+
+	run_cmd "$IP neigh get 203.0.113.255 dev dummy0"
+	log_test $? 2 "Unresolved neighbour for network broadcast address"
+
+	cleanup
+}
+
 ################################################################################
 # usage
 
@@ -2028,6 +2083,7 @@ do
 	ipv4_route_v6_gw)		ipv4_route_v6_gw_test;;
 	ipv4_mangle)			ipv4_mangle_test;;
 	ipv6_mangle)			ipv6_mangle_test;;
+	ipv4_bcast_neigh)		ipv4_bcast_neigh_test;;
 
 	help) echo "Test names: $TESTS"; exit 0;;
 	esac