Merge pull request #4833 from c-po/fix-veth-removal

veth: T7990: fix stale DHCP clients when removing virtual Ethernet pairs

2 files changed, 27 insertions, 3 deletions

diff --git a/python/vyos/ifconfig/interface.py b/python/vyos/ifconfig/interface.py
index ad634c4d7..f03d0cb68 100644
--- a/python/vyos/ifconfig/interface.py
+++ b/python/vyos/ifconfig/interface.py
@@ -371,7 +371,7 @@ class Interface(Control):
         if 'netns' in self.config: cmd = f'ip netns exec {netns} {cmd}'
         self._cmd(cmd)
 
-    def remove(self):
+    def remove(self, skip_delete=False):
         """
         Remove interface from operating system. Removing the interface
         deconfigures all assigned IP addresses and clear possible DHCP(v6)
@@ -388,12 +388,20 @@ class Interface(Control):
 
         # remove all assigned IP addresses from interface - this is a bit redundant
         # as the kernel will remove all addresses on interface deletion, but we
-        # can not delete ALL interfaces, see below
+        # can not delete ALL interfaces, see below.
+        #
+        # This will internally stop DHCP(v6) if running
         self.flush_addrs()
 
         # remove interface from conntrack VRF interface map
         self._del_interface_from_ct_iface_map()
 
+        # Some interfaces - mainly veth pairs - should be properly de-configured
+        # but not deleted. Deleting one veth pair member will delete the other,
+        # we need need a way to skip the deletion.
+        if skip_delete:
+            return
+
         # ---------------------------------------------------------------------
         # Any class can define an eternal regex in its definition
         # interface matching the regex will not be deleted
diff --git a/python/vyos/ifconfig/veth.py b/python/vyos/ifconfig/veth.py
index f4075fa02..9868ea526 100644
--- a/python/vyos/ifconfig/veth.py
+++ b/python/vyos/ifconfig/veth.py
@@ -14,7 +14,8 @@
 # License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 from vyos.ifconfig.interface import Interface
-
+from vyos.utils.dict import dict_search
+from vyos.utils.network import get_interface_config
 
 @Interface.register
 class VethIf(Interface):
@@ -51,3 +52,18 @@ class VethIf(Interface):
 
         # interface is always A/D down. It needs to be enabled explicitly
         self.set_admin_state('down')
+
+    def remove(self):
+        # The oddity with virtual-ethernet pairs is, if you delete one - the OS
+        # Kernel will immediately delete the other interface, leaving no
+        # possibility to properly shutdown the peer-interface.
+        #
+        # We deconfigure the second veth pair interface during deletion, but
+        # skip it's actual call to "ip link del dev ..."
+        tmp = get_interface_config(self.ifname)
+        peer = tmp.get('link', dict_search('linkinfo.info_kind', tmp))
+        if peer != None:
+            Interface(peer).remove(skip_delete=True)
+
+        # always forward to the base class
+        super().remove()