selftests: fcnal: Test SO_DONTROUTE on TCP sockets.

Use nettest --{client,server}-dontroute to test the kernel behaviour
with TCP sockets having the SO_DONTROUTE option. Sending packets to a
neighbour (on link) host, should work. When the host is behind a
router, sending should fail.

Client and server sockets are tested independently, so that we can
cover different TCP kernel paths.

SO_DONTROUTE also affects the syncookies path. So ipv4_tcp_dontroute()
is made to work with or without syncookies, to cover both paths.

Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 21ca914..3a1f305 100755 (executable)
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -1098,6 +1098,59 @@ test_ipv4_md5_vrf__global_server__bind_ifindex0()
        set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
 }
 
+ipv4_tcp_dontroute()
+{
+       local syncookies=$1
+       local nsa_syncookies
+       local nsb_syncookies
+       local a
+
+       #
+       # Link local connection tests (SO_DONTROUTE).
+       # Connections should succeed only when the remote IP address is
+       # on link (doesn't need to be routed through a gateway).
+       #
+
+       nsa_syncookies=$(ip netns exec "${NSA}" sysctl -n net.ipv4.tcp_syncookies)
+       nsb_syncookies=$(ip netns exec "${NSB}" sysctl -n net.ipv4.tcp_syncookies)
+       ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+       ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${syncookies}
+
+       # Test with eth1 address (on link).
+
+       a=${NSB_IP}
+       log_start
+       do_run_cmd nettest -B -N "${NSA}" -O "${NSB}" -r ${a} --client-dontroute
+       log_test_addr ${a} $? 0 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+       a=${NSB_IP}
+       log_start
+       do_run_cmd nettest -B -N "${NSA}" -O "${NSB}" -r ${a} --server-dontroute
+       log_test_addr ${a} $? 0 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+       # Test with loopback address (routed).
+       #
+       # The client would use the eth1 address as source IP by default.
+       # Therefore, we need to use the -c option here, to force the use of the
+       # routed (loopback) address as source IP (so that the server will try
+       # to respond to a routed address and not a link local one).
+
+       a=${NSB_LO_IP}
+       log_start
+       show_hint "Should fail 'Network is unreachable' since server is not on link"
+       do_run_cmd nettest -B -N "${NSA}" -O "${NSB}" -c "${NSA_LO_IP}" -r ${a} --client-dontroute
+       log_test_addr ${a} $? 1 "SO_DONTROUTE client, syncookies=${syncookies}"
+
+       a=${NSB_LO_IP}
+       log_start
+       show_hint "Should timeout since server cannot respond (client is not on link)"
+       do_run_cmd nettest -B -N "${NSA}" -O "${NSB}" -c "${NSA_LO_IP}" -r ${a} --server-dontroute
+       log_test_addr ${a} $? 2 "SO_DONTROUTE server, syncookies=${syncookies}"
+
+       ip netns exec "${NSB}" sysctl -wq net.ipv4.tcp_syncookies=${nsb_syncookies}
+       ip netns exec "${NSA}" sysctl -wq net.ipv4.tcp_syncookies=${nsa_syncookies}
+}
+
 ipv4_tcp_novrf()
 {
        local a
@@ -1217,6 +1270,9 @@ ipv4_tcp_novrf()
        log_test_addr ${a} $? 1 "No server, device client, local conn"
 
        ipv4_tcp_md5_novrf
+
+       ipv4_tcp_dontroute 0
+       ipv4_tcp_dontroute 2
 }
 
 ipv4_tcp_vrf()