selftests: mptcp: enable syncookie only in absence of reorders

Syncookie validation may fail for OoO packets, causing spurious
resets and self-tests failures, so let's force syncookie only
for tests iteration with no OoO.

Fixes: fed61c4b584c ("selftests: mptcp: make 2nd net namespace use tcp syn cookies unconditionally")
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/198
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 9ca5f1b..2b495dc 100755 (executable)
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -197,9 +197,6 @@ ip -net "$ns4" link set ns4eth3 up
 ip -net "$ns4" route add default via 10.0.3.2
 ip -net "$ns4" route add default via dead:beef:3::2
 
-# use TCP syn cookies, even if no flooding was detected.
-ip netns exec "$ns2" sysctl -q net.ipv4.tcp_syncookies=2
-
 set_ethtool_flags() {
        local ns="$1"
        local dev="$2"
@@ -737,6 +734,14 @@ for sender in $ns1 $ns2 $ns3 $ns4;do
                exit $ret
        fi
 
+       # ns1<->ns2 is not subject to reordering/tc delays. Use it to test
+       # mptcp syncookie support.
+       if [ $sender = $ns1 ]; then
+               ip netns exec "$ns2" sysctl -q net.ipv4.tcp_syncookies=2
+       else
+               ip netns exec "$ns2" sysctl -q net.ipv4.tcp_syncookies=1
+       fi
+
        run_tests "$ns2" $sender 10.0.1.2
        run_tests "$ns2" $sender dead:beef:1::2
        run_tests "$ns2" $sender 10.0.2.1