selftests: mptcp: add tests for subflow creation failure

Verify that, when multiple endpoints are available, subflows
creation proceed even when the first additional subflow creation
fails - due to packet drop on the relevant link

Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/mptcp/config

@@ -18,4 +18,5 @@ CONFIG_NFT_TPROXY=m
 CONFIG_NFT_SOCKET=m
 CONFIG_IP_ADVANCED_ROUTER=y
 CONFIG_IP_MULTIPLE_TABLES=y
+CONFIG_IP_NF_TARGET_REJECT=m
 CONFIG_IPV6_MULTIPLE_TABLES=y

tools/testing/selftests/net/mptcp/mptcp_join.sh

@@ -975,6 +975,22 @@ chk_link_usage()
  fi
 }
 
+wait_for_tw()
+{
+ local timeout_ms=$((timeout_poll * 1000))
+ local time=0
+ local ns=$1
+
+ while [ $time -lt $timeout_ms ]; do
+ local cnt=$(ip netns exec $ns ss -t state time-wait |wc -l)
+
+ [ "$cnt" = 1 ] && return 1
+ time=$((time + 100))
+ sleep 0.1
+ done
+ return 1
+}
+
 subflows_tests()
 {
  reset
@@ -1032,6 +1048,61 @@ subflows_tests()
  chk_join_nr "single subflow, dev" 1 1 1
 }
 
+subflows_error_tests()
+{
+ # If a single subflow is configured, and matches the MPC src
+ # address, no additional subflow should be created
+ reset
+ ip netns exec $ns1 ./pm_nl_ctl limits 0 1
+ ip netns exec $ns2 ./pm_nl_ctl limits 0 1
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.1.2 flags subflow
+ run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+ chk_join_nr "no MPC address reuse with single endpoint" 0 0 0
+
+ # multiple subflows, with subflow creation error
+ reset
+ ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+ ip netns exec $ns2 ./pm_nl_ctl limits 0 2
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+ ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
+ run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+ chk_join_nr "multiple subflows, with failing subflow" 1 1 1
+
+ # multiple subflows, with subflow timeout on MPJ
+ reset
+ ip netns exec $ns1 ./pm_nl_ctl limits 0 2
+ ip netns exec $ns2 ./pm_nl_ctl limits 0 2
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+ ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j DROP
+ run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow
+ chk_join_nr "multiple subflows, with subflow timeout" 1 1 1
+
+ # multiple subflows, check that the endpoint corresponding to
+ # closed subflow (due to reset) is not reused if additional
+ # subflows are added later
+ reset
+ ip netns exec $ns1 ./pm_nl_ctl limits 0 1
+ ip netns exec $ns2 ./pm_nl_ctl limits 0 1
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.3.2 flags subflow
+ ip netns exec $ns1 iptables -A INPUT -s 10.0.3.2 -p tcp -j REJECT
+ run_tests $ns1 $ns2 10.0.1.1 0 0 0 slow &
+
+ # updates in the child shell do not have any effect here, we
+ # need to bump the test counter for the above case
+ TEST_COUNT=$((TEST_COUNT))
+
+ # mpj subflow will be in TW after the reset
+ wait_for_tw $ns2
+ ip netns exec $ns2 ./pm_nl_ctl add 10.0.2.2 flags subflow
+ wait
+
+ # additional subflow could be created only if the PM select
+ # the later endpoint, skipping the already used one
+ chk_join_nr "multiple subflows, fair usage on close" 1 1 1
+}
+
 signal_address_tests()
 {
  # add_address, unused
@@ -1843,6 +1914,7 @@ fullmesh_tests()
 all_tests()
 {
  subflows_tests
+ subflows_error_tests
  signal_address_tests
  link_failure_tests
  add_addr_timeout_tests
@@ -1862,6 +1934,7 @@ usage()
 {
  echo "mptcp_join usage:"
  echo " -f subflows_tests"
+ echo " -e subflows_error_tests"
  echo " -s signal_address_tests"
  echo " -l link_failure_tests"
  echo " -t add_addr_timeout_tests"
@@ -1910,11 +1983,14 @@ if [ $do_all_tests -eq 1 ]; then
  exit $ret
 fi
 
-while getopts 'fsltra64bpkdmchCS' opt; do
+while getopts 'fesltra64bpkdmchCS' opt; do
  case $opt in
  f)
  subflows_tests
  ;;
+ e)
+ subflows_error_tests
+ ;;
  s)
  signal_address_tests
  ;;