selftests: mptcp: join: test for flush/re-add endpoints

After having flushed endpoints that didn't cause the creation of new
subflows, it is important to check endpoints can be re-created, re-using
previously used IDs.

Before the previous commit, the client would not have been able to
re-create the subflow that was previously rejected.

The 'Fixes' tag here below is the same as the one from the previous
commit: this patch here is not fixing anything wrong in the selftests,
but it validates the previous fix for an issue introduced by this commit
ID.

Fixes: 06faa2271034 ("mptcp: remove multi addresses and subflows in PM")
Cc: stable@vger.kernel.org
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240819-net-mptcp-pm-reusing-id-v1-6-38035d40de5b@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index fbb0174145ad32bfad98b93fc4d5e85adf4116e1..f609c02c6123e6baada5a47affb2e96f532b9a6f 100755 (executable)
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -3651,6 +3651,36 @@ endpoint_tests()
                chk_rm_nr 2 1 invert
        fi
 
+       # flush and re-add
+       if reset_with_tcp_filter "flush re-add" ns2 10.0.3.2 REJECT OUTPUT &&
+          mptcp_lib_kallsyms_has "subflow_rebuild_header$"; then
+               pm_nl_set_limits $ns1 0 2
+               pm_nl_set_limits $ns2 1 2
+               # broadcast IP: no packet for this address will be received on ns1
+               pm_nl_add_endpoint $ns1 224.0.0.1 id 2 flags signal
+               pm_nl_add_endpoint $ns2 10.0.3.2 id 3 flags subflow
+               test_linkfail=4 speed=20 \
+                       run_tests $ns1 $ns2 10.0.1.1 &
+               local tests_pid=$!
+
+               wait_attempt_fail $ns2
+               chk_subflow_nr "before flush" 1
+               chk_mptcp_info subflows 0 subflows 0
+
+               pm_nl_flush_endpoint $ns2
+               pm_nl_flush_endpoint $ns1
+               wait_rm_addr $ns2 0
+               ip netns exec "${ns2}" ${iptables} -D OUTPUT -s "10.0.3.2" -p tcp -j REJECT
+               pm_nl_add_endpoint $ns2 10.0.3.2 id 3 flags subflow
+               wait_mpj $ns2
+               pm_nl_add_endpoint $ns1 10.0.3.1 id 2 flags signal
+               wait_mpj $ns2
+               mptcp_lib_kill_wait $tests_pid
+
+               chk_join_nr 2 2 2
+               chk_add_nr 2 2
+               chk_rm_nr 1 0 invert
+       fi
 }
 
 # [$1: error message]