default-route: also configure default-routes for assumed connections

Previously for assumed connections we would never configure a default route.
That has serious problems for example in the following two scenarios:

  - the default-route might have a limited lifetime from a previous
    SLAAC/accept_ra setting. In this case, once we assume the connection
    we must also ensure that we extend the lifetime of the default
    route.
  - the gateway could be received via DHCP/RA and it might change.
    If we ignore default-routes for assumed connection we miss that
    change.

The problem is that the notion of "assumed connection" wrongly combines
two conflicting goals (related bug bgo#746440):
  a) have an external device that is entirely unmanged by NM.
  b) do a seamless takeover of a previously managed connection at start,
     but still fully manage.

This patch changes the handling of default-routes towards meaning b).

https://bugzilla.redhat.com/show_bug.cgi?id=1224291

1 files changed, 13 insertions, 7 deletions

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index f8fcf70ed4..35418ccb17 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -3093,7 +3093,7 @@ ip4_config_merge_and_apply (NMDevice *self,
 	if (priv->wwan_ip4_config)
 		nm_ip4_config_merge (composite, priv->wwan_ip4_config);
 
-	/* Merge user overrides into the composite config. For assumed connection,
+	/* Merge user overrides into the composite config. For assumed connections,
 	 * con_ip4_config is empty. */
 	if (priv->con_ip4_config)
 		nm_ip4_config_merge (composite, priv->con_ip4_config);
@@ -3122,14 +3122,12 @@ ip4_config_merge_and_apply (NMDevice *self,
 		goto END_ADD_DEFAULT_ROUTE;
 	}
 
-	if (nm_device_uses_assumed_connection (self))
-		goto END_ADD_DEFAULT_ROUTE;
-
 	connection_has_default_route
 	    = nm_default_route_manager_ip4_connection_has_default_route (nm_default_route_manager_get (),
 	                                                                 connection, &connection_is_never_default);
 
 	if (   !priv->default_route.v4_configure_first_time
+	    && !nm_device_uses_assumed_connection (self)
 	    && connection_is_never_default) {
 		/* If the connection is explicitly configured as never-default, we enforce the (absense of the)
 		 * default-route only once. That allows the user to configure a connection as never-default,
@@ -3137,6 +3135,11 @@ ip4_config_merge_and_apply (NMDevice *self,
 		goto END_ADD_DEFAULT_ROUTE;
 	}
 
+	/* At this point, we treat assumed and non-assumed connections alike.
+	 * For assumed connections we do that because we still manage RA and DHCP
+	 * leases for them, so we must extend/update the default route on commits.
+	 */
+
 	/* we are about to commit (for a non-assumed connection). Enforce whatever we have
 	 * configured. */
 	priv->default_route.v4_configure_first_time = FALSE;
@@ -3716,14 +3719,12 @@ ip6_config_merge_and_apply (NMDevice *self,
 		goto END_ADD_DEFAULT_ROUTE;
 	}
 
-	if (nm_device_uses_assumed_connection (self))
-		goto END_ADD_DEFAULT_ROUTE;
-
 	connection_has_default_route
 	    = nm_default_route_manager_ip6_connection_has_default_route (nm_default_route_manager_get (),
 	                                                                 connection, &connection_is_never_default);
 
 	if (   !priv->default_route.v6_configure_first_time
+	    && !nm_device_uses_assumed_connection (self)
 	    && connection_is_never_default) {
 		/* If the connection is explicitly configured as never-default, we enforce the (absence of the)
 		 * default-route only once. That allows the user to configure a connection as never-default,
@@ -3731,6 +3732,11 @@ ip6_config_merge_and_apply (NMDevice *self,
 		goto END_ADD_DEFAULT_ROUTE;
 	}
 
+	/* At this point, we treat assumed and non-assumed connections alike.
+	 * For assumed connections we do that because we still manage RA and DHCP
+	 * leases for them, so we must extend/update the default route on commits.
+	 */
+
 	/* we are about to commit (for a non-assumed connection). Enforce whatever we have
 	 * configured. */
 	priv->default_route.v6_configure_first_time = FALSE;