tunnel: T3366: support changing tunnel parameters for gre-bridge

Linux prevents changing parameters on a gretap (which is used by gre-bridge)
interfaces. To overcome this limitation a tunnel must be destroyed and recreated
on demand when gre-bridge is used.

2 files changed, 52 insertions, 4 deletions

diff --git a/smoketest/scripts/cli/test_interfaces_tunnel.py b/smoketest/scripts/cli/test_interfaces_tunnel.py
index 5f3791655..a041427a8 100755
--- a/smoketest/scripts/cli/test_interfaces_tunnel.py
+++ b/smoketest/scripts/cli/test_interfaces_tunnel.py
@@ -19,6 +19,7 @@ import json
 
 from vyos.configsession import ConfigSession
 from vyos.configsession import ConfigSessionError
+from vyos.template import inc_ip
 from vyos.util import cmd
 
 from base_interfaces_test import BasicInterfaceTest
@@ -203,5 +204,35 @@ class TunnelInterfaceTest(BasicInterfaceTest.BaseTest):
         # Check if commit is ok
         self.session.commit()
 
+    def test_gretap_parameters_change(self):
+        interface = f'tun1040'
+        gre_key = '10'
+        encapsulation = 'gre-bridge'
+        tos = '20'
+
+        self.session.set(self._base_path + [interface, 'encapsulation', encapsulation])
+        self.session.set(self._base_path + [interface, 'local-ip', self.local_v4])
+        self.session.set(self._base_path + [interface, 'remote-ip', remote_ip4])
+
+        # Check if commit is ok
+        self.session.commit()
+
+        conf = tunnel_conf(interface)
+        self.assertEqual(mtu,           conf['mtu'])
+        self.assertEqual(interface,     conf['ifname'])
+        self.assertEqual('gretap',      conf['linkinfo']['info_kind'])
+        self.assertEqual(self.local_v4, conf['linkinfo']['info_data']['local'])
+        self.assertEqual(remote_ip4,    conf['linkinfo']['info_data']['remote'])
+        self.assertEqual(0,             conf['linkinfo']['info_data']['ttl'])
+
+        # Change remote ip address (inc host by 2
+        new_remote = inc_ip(remote_ip4, 2)
+        self.session.set(self._base_path + [interface, 'remote-ip', new_remote])
+        # Check if commit is ok
+        self.session.commit()
+
+        conf = tunnel_conf(interface)
+        self.assertEqual(new_remote,    conf['linkinfo']['info_data']['remote'])
+
 if __name__ == '__main__':
     unittest.main(verbosity=2)
diff --git a/src/conf_mode/interfaces-tunnel.py b/src/conf_mode/interfaces-tunnel.py
index cb6dca222..748a9d261 100755
--- a/src/conf_mode/interfaces-tunnel.py
+++ b/src/conf_mode/interfaces-tunnel.py
@@ -40,11 +40,22 @@ from vyos.ifconfig import SitIf
 from vyos.ifconfig import Sit6RDIf
 from vyos.template import is_ipv4
 from vyos.template import is_ipv6
+from vyos.util import cmd
 from vyos.util import dict_search
 from vyos import ConfigError
 from vyos import airbag
 airbag.enable()
 
+def get_tunnel_encapsulation(interface):
+    """ Returns the used encapsulation protocol for given interface.
+        If interface does not exist, None is returned.
+    """
+    if not os.path.exists(f'/sys/class/net/{interface}'):
+        return None
+    from json import loads
+    tmp = loads(cmd(f'ip -d -j link show {interface}'))[0]
+    return tmp['linkinfo']['info_kind']
+
 def get_config(config=None):
     """
     Retrive CLI config as dictionary. Dictionary can never be empty, as at least
@@ -124,9 +135,15 @@ def generate(tunnel):
     return None
 
 def apply(tunnel):
-    if 'deleted' in tunnel or 'encapsulation_changed' in tunnel:
-        if tunnel['ifname'] in interfaces():
-            tmp = Interface(tunnel['ifname'])
+    # If a gre-bridge tunnel is already existing we can not "simply" change
+    # local or remote addresses. This returns "Operation not supported" by the
+    # Kernel. There is no other solution to destroy and recreate the tunnel.
+    interface = tunnel['ifname']
+    encap = get_tunnel_encapsulation(interface)
+
+    if 'deleted' in tunnel or 'encapsulation_changed' in tunnel or encap == 'gretap':
+        if interface in interfaces():
+            tmp = Interface(interface)
             tmp.remove()
         if 'deleted' in tunnel:
             return None
@@ -175,7 +192,7 @@ def apply(tunnel):
         if dict_search(our_key, tunnel) and their_key in conf:
             conf[their_key] = dict_search(our_key, tunnel)
 
-    tun = klass(tunnel['ifname'], **conf)
+    tun = klass(interface, **conf)
     tun.change_options()
     tun.update(tunnel)