interface: T6592: remove interface from conntrack ct_iface_map on deletion

We always have had stale interface entries in the ct_iface_map of nftables/
conntrack for any interface that once belonged to a VRF.

This commit will always clean the nftables interface map when the interface
is deleted from the system.

(cherry picked from commit 17c12bde5c6f314311e7524842fd1ddc254009b4)

3 files changed, 45 insertions, 33 deletions

diff --git a/python/vyos/ifconfig/interface.py b/python/vyos/ifconfig/interface.py
index 748830004..72d3d3afe 100644
--- a/python/vyos/ifconfig/interface.py
+++ b/python/vyos/ifconfig/interface.py
@@ -383,6 +383,9 @@ class Interface(Control):
         # can not delete ALL interfaces, see below
         self.flush_addrs()
 
+        # remove interface from conntrack VRF interface map
+        self._del_interface_from_ct_iface_map()
+
         # ---------------------------------------------------------------------
         # Any class can define an eternal regex in its definition
         # interface matching the regex will not be deleted
@@ -403,36 +406,20 @@ class Interface(Control):
         if netns: cmd = f'ip netns exec {netns} {cmd}'
         return self._cmd(cmd)
 
-    def _set_vrf_ct_zone(self, vrf, old_vrf_tableid=None):
-        """
-        Add/Remove rules in nftables to associate traffic in VRF to an
-        individual conntack zone
-        """
-        # Don't allow for netns yet
-        if 'netns' in self.config:
-            return None
-
-        def nft_check_and_run(nft_command):
-            # Check if deleting is possible first to avoid raising errors
-            _, err = self._popen(f'nft --check {nft_command}')
-            if not err:
-                # Remove map element
-                self._cmd(f'nft {nft_command}')
+    def _nft_check_and_run(self, nft_command):
+        # Check if deleting is possible first to avoid raising errors
+        _, err = self._popen(f'nft --check {nft_command}')
+        if not err:
+            # Remove map element
+            self._cmd(f'nft {nft_command}')
 
-        if vrf:
-            # Get routing table ID for VRF
-            vrf_table_id = get_vrf_tableid(vrf)
-            # Add map element with interface and zone ID
-            if vrf_table_id:
-                # delete old table ID from nftables if it has changed, e.g. interface moved to a different VRF
-                if old_vrf_tableid and old_vrf_tableid != int(vrf_table_id):
-                    nft_del_element = f'delete element inet vrf_zones ct_iface_map {{ "{self.ifname}" }}'
-                    nft_check_and_run(nft_del_element)
+    def _del_interface_from_ct_iface_map(self):
+        nft_command = f'delete element inet vrf_zones ct_iface_map {{ "{self.ifname}" }}'
+        self._nft_check_and_run(nft_command)
 
-                self._cmd(f'nft add element inet vrf_zones ct_iface_map {{ "{self.ifname}" : {vrf_table_id} }}')
-        else:
-            nft_del_element = f'delete element inet vrf_zones ct_iface_map {{ "{self.ifname}" }}'
-            nft_check_and_run(nft_del_element)
+    def _add_interface_to_ct_iface_map(self, vrf_table_id: int):
+        nft_command = f'add element inet vrf_zones ct_iface_map {{ "{self.ifname}" : {vrf_table_id} }}'
+        self._nft_check_and_run(nft_command)
 
     def get_min_mtu(self):
         """
@@ -605,6 +592,10 @@ class Interface(Control):
         >>> Interface('eth0').set_vrf()
         """
 
+        # Don't allow for netns yet
+        if 'netns' in self.config:
+            return False
+
         tmp = self.get_interface('vrf')
         if tmp == vrf:
             return False
@@ -612,7 +603,19 @@ class Interface(Control):
         # Get current VRF table ID
         old_vrf_tableid = get_vrf_tableid(self.ifname)
         self.set_interface('vrf', vrf)
-        self._set_vrf_ct_zone(vrf, old_vrf_tableid)
+
+        if vrf:
+            # Get routing table ID number for VRF
+            vrf_table_id = get_vrf_tableid(vrf)
+            # Add map element with interface and zone ID
+            if vrf_table_id:
+                # delete old table ID from nftables if it has changed, e.g. interface moved to a different VRF
+                if old_vrf_tableid and old_vrf_tableid != int(vrf_table_id):
+                    self._del_interface_from_ct_iface_map()
+                self._add_interface_to_ct_iface_map(vrf_table_id)
+        else:
+            self._del_interface_from_ct_iface_map()
+
         return True
 
     def set_arp_cache_tmo(self, tmo):
diff --git a/python/vyos/ifconfig/l2tpv3.py b/python/vyos/ifconfig/l2tpv3.py
index 85a89ef8b..c1f2803ee 100644
--- a/python/vyos/ifconfig/l2tpv3.py
+++ b/python/vyos/ifconfig/l2tpv3.py
@@ -90,9 +90,17 @@ class L2TPv3If(Interface):
         """
 
         if self.exists(self.ifname):
-            # interface is always A/D down. It needs to be enabled explicitly
             self.set_admin_state('down')
 
+            # remove all assigned IP addresses from interface - this is a bit redundant
+            # as the kernel will remove all addresses on interface deletion
+            self.flush_addrs()
+
+            # remove interface from conntrack VRF interface map, here explicitly and do not
+            # rely on the base class implementation as the interface will
+            # vanish as soon as the l2tp session is deleted
+            self._del_interface_from_ct_iface_map()
+
             if {'tunnel_id', 'session_id'} <= set(self.config):
                 cmd = 'ip l2tp del session tunnel_id {tunnel_id}'
                 cmd += ' session_id {session_id}'
@@ -101,3 +109,5 @@ class L2TPv3If(Interface):
             if 'tunnel_id' in self.config:
                 cmd = 'ip l2tp del tunnel tunnel_id {tunnel_id}'
                 self._cmd(cmd.format(**self.config))
+
+            # No need to call the baseclass as the interface is now already gone
diff --git a/smoketest/scripts/cli/test_interfaces_l2tpv3.py b/smoketest/scripts/cli/test_interfaces_l2tpv3.py
index af3d49f75..abc55e6d2 100755
--- a/smoketest/scripts/cli/test_interfaces_l2tpv3.py
+++ b/smoketest/scripts/cli/test_interfaces_l2tpv3.py
@@ -20,7 +20,7 @@ import unittest
 
 from base_interfaces_test import BasicInterfaceTest
 from vyos.utils.process import cmd
-
+from vyos.utils.kernel import unload_kmod
 class L2TPv3InterfaceTest(BasicInterfaceTest.TestCase):
     @classmethod
     def setUpClass(cls):
@@ -62,7 +62,6 @@ if __name__ == '__main__':
     # reloaded on demand - not needed but test more and more features
     for module in ['l2tp_ip6', 'l2tp_ip', 'l2tp_eth', 'l2tp_eth',
                    'l2tp_netlink', 'l2tp_core']:
-        if os.path.exists(f'/sys/module/{module}'):
-            cmd(f'sudo rmmod {module}')
+        unload_kmod(module)
 
     unittest.main(verbosity=2)