ipsec: input: drop by default for non-matching pkts

As per IPSec RFC4301 [1], any non-matching packets should be dropped by
default. This is handled correctly in ipsec_output.c, however in
ipsec_input.c non-matching packets are allowed to pass as per a matched
BYPASS rule.

For full details, see:
https://lists.fd.io/g/vpp-dev/topic/ipsec_input_output_default/84943480

It appears the ipsec6_input_node only matches PROTECT policies. Until
this is extended to handle BYPASS + DISCARD, we may wish to not drop
by default here, since all IPv6 traffic not matching a PROTECT policy
will be dropped.

[1]: https://datatracker.ietf.org/doc/html/rfc4301

Type: fix
Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
Change-Id: Iddbfd008dbe082486d1928f6a10ffbd83d859a20

1 files changed, 156 insertions, 0 deletions

diff --git a/test/test_ipsec_default.py b/test/test_ipsec_default.py
new file mode 100644
index 00000000000..71bbd759297
--- /dev/null
+++ b/test/test_ipsec_default.py
@@ -0,0 +1,156 @@
+import socket
+import unittest
+
+from util import ppp
+from framework import VppTestRunner
+from template_ipsec import IPSecIPv4Fwd
+
+"""
+When an IPSec SPD is configured on an interface, any inbound packets
+not matching inbound policies, or outbound packets not matching outbound
+policies, must be dropped by default as per RFC4301.
+
+This test uses simple IPv4 forwarding on interfaces with IPSec enabled
+to check if packets with no matching rules are dropped by default.
+
+The basic setup is a single SPD bound to two interfaces, pg0 and pg1.
+
+                    ┌────┐        ┌────┐
+                    │SPD1│        │SPD1│
+                    ├────┤ ─────> ├────┤
+                    │PG0 │        │PG1 │
+                    └────┘        └────┘
+
+First, both inbound and outbound BYPASS policies are configured allowing
+traffic to pass from pg0 -> pg1.
+
+Packets are captured and verified at pg1.
+
+Then either the inbound or outbound policies are removed and we verify
+packets are dropped as expected.
+
+"""
+
+
+class IPSecInboundDefaultDrop(IPSecIPv4Fwd):
+    """ IPSec: inbound packets drop by default with no matching rule """
+    def test_ipsec_inbound_default_drop(self):
+        # configure two interfaces and bind the same SPD to both
+        self.create_interfaces(2)
+        self.spd_create_and_intf_add(1, self.pg_interfaces)
+        pkt_count = 5
+
+        # catch-all inbound BYPASS policy, all interfaces
+        inbound_policy = self.spd_add_rem_policy(
+            1, None, None, socket.IPPROTO_UDP, is_out=0, priority=10,
+            policy_type="bypass", all_ips=True)
+
+        # outbound BYPASS policy allowing traffic from pg0->pg1
+        outbound_policy = self.spd_add_rem_policy(
+            1, self.pg0, self.pg1, socket.IPPROTO_UDP,
+            is_out=1, priority=10, policy_type="bypass")
+
+        # create a packet stream pg0->pg1 + add to pg0
+        packets0 = self.create_stream(self.pg0, self.pg1, pkt_count)
+        self.pg0.add_stream(packets0)
+
+        # with inbound BYPASS rule at pg0, we expect to see forwarded
+        # packets on pg1
+        self.pg_interfaces[1].enable_capture()
+        self.pg_start()
+        cap1 = self.pg1.get_capture()
+        for packet in cap1:
+            try:
+                self.logger.debug(ppp("SPD - Got packet:", packet))
+            except Exception:
+                self.logger.error(
+                    ppp("Unexpected or invalid packet:", packet))
+                raise
+        self.logger.debug("SPD: Num packets: %s", len(cap1.res))
+        # verify captures on pg1
+        self.verify_capture(self.pg0, self.pg1, cap1)
+        # verify policies matched correct number of times
+        self.verify_policy_match(pkt_count, inbound_policy)
+        self.verify_policy_match(pkt_count, outbound_policy)
+
+        # remove inbound catch-all BYPASS rule, traffic should now be dropped
+        self.spd_add_rem_policy(  # inbound, all interfaces
+            1, None, None, socket.IPPROTO_UDP, is_out=0, priority=10,
+            policy_type="bypass", all_ips=True, remove=True)
+
+        # create another packet stream pg0->pg1 + add to pg0
+        packets1 = self.create_stream(self.pg0, self.pg1, pkt_count)
+        self.pg0.add_stream(packets1)
+        self.pg_interfaces[1].enable_capture()
+        self.pg_start()
+        # confirm traffic has now been dropped
+        self.pg1.assert_nothing_captured("inbound pkts with no matching \
+            rules NOT dropped by default")
+        # both policies should not have matched any further packets
+        # since we've dropped at input stage
+        self.verify_policy_match(pkt_count, outbound_policy)
+        self.verify_policy_match(pkt_count, inbound_policy)
+
+
+class IPSecOutboundDefaultDrop(IPSecIPv4Fwd):
+    """ IPSec: outbound packets drop by default with no matching rule """
+    def test_ipsec_inbound_default_drop(self):
+        # configure two interfaces and bind the same SPD to both
+        self.create_interfaces(2)
+        self.spd_create_and_intf_add(1, self.pg_interfaces)
+        pkt_count = 5
+
+        # catch-all inbound BYPASS policy, all interfaces
+        inbound_policy = self.spd_add_rem_policy(
+            1, None, None, socket.IPPROTO_UDP, is_out=0, priority=10,
+            policy_type="bypass", all_ips=True)
+
+        # outbound BYPASS policy allowing traffic from pg0->pg1
+        outbound_policy = self.spd_add_rem_policy(
+            1, self.pg0, self.pg1, socket.IPPROTO_UDP,
+            is_out=1, priority=10, policy_type="bypass")
+
+        # create a packet stream pg0->pg1 + add to pg0
+        packets0 = self.create_stream(self.pg0, self.pg1, pkt_count)
+        self.pg0.add_stream(packets0)
+
+        # with outbound BYPASS rule allowing pg0->pg1, we expect to see
+        # forwarded packets on pg1
+        self.pg_interfaces[1].enable_capture()
+        self.pg_start()
+        cap1 = self.pg1.get_capture()
+        for packet in cap1:
+            try:
+                self.logger.debug(ppp("SPD - Got packet:", packet))
+            except Exception:
+                self.logger.error(
+                    ppp("Unexpected or invalid packet:", packet))
+                raise
+        self.logger.debug("SPD: Num packets: %s", len(cap1.res))
+        # verify captures on pg1
+        self.verify_capture(self.pg0, self.pg1, cap1)
+        # verify policies matched correct number of times
+        self.verify_policy_match(pkt_count, inbound_policy)
+        self.verify_policy_match(pkt_count, outbound_policy)
+
+        # remove outbound rule
+        self.spd_add_rem_policy(
+            1, self.pg0, self.pg1, socket.IPPROTO_UDP,
+            is_out=1, priority=10, policy_type="bypass",
+            remove=True)
+
+        # create another packet stream pg0->pg1 + add to pg0
+        packets1 = self.create_stream(self.pg0, self.pg1, pkt_count)
+        self.pg0.add_stream(packets1)
+        self.pg_interfaces[1].enable_capture()
+        self.pg_start()
+        # confirm traffic was dropped and not forwarded
+        self.pg1.assert_nothing_captured("outbound pkts with no matching \
+            rules NOT dropped by default")
+        # inbound rule should have matched twice the # of pkts now
+        self.verify_policy_match(pkt_count*2, inbound_policy)
+        # as dropped at outbound, outbound policy is the same
+        self.verify_policy_match(pkt_count, outbound_policy)
+
+if __name__ == '__main__':
+    unittest.main(testRunner=VppTestRunner)