networkd: link - drop foreign config when configuring link

This is a change in behavior:

Before we would never remove any state, only add to it, we now drop unwanted
state from any link the moment we start managing it.

Note however, that we still will not remove any foreign state added at runtime,
to avoid any feedback loops. However, we make no guarantees about coexisting
with third-party tools that change the state of the links we manage.

1 files changed, 33 insertions, 0 deletions

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index a7d0908bdd..00c57b2960 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -2017,6 +2017,35 @@ static int link_set_ipv6_hop_limit(Link *link) {
         return 0;
 }
 
+static int link_drop_foreign_config(Link *link) {
+        Address *address;
+        Route *route;
+        Iterator i;
+        int r;
+
+        SET_FOREACH(address, link->addresses_foreign, i) {
+                /* we consider IPv6LL addresses to be managed by the kernel */
+                if (address->family == AF_INET6 && in_addr_is_link_local(AF_INET6, &address->in_addr) == 1)
+                        continue;
+
+                r = address_remove(address, link, link_address_remove_handler);
+                if (r < 0)
+                        return r;
+        }
+
+        SET_FOREACH(route, link->routes_foreign, i) {
+                /* do not touch routes managed by the kernel */
+                if (route->protocol == RTPROT_KERNEL)
+                        continue;
+
+                r = route_remove(route, link, link_address_remove_handler);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
 static int link_configure(Link *link) {
         int r;
 
@@ -2024,6 +2053,10 @@ static int link_configure(Link *link) {
         assert(link->network);
         assert(link->state == LINK_STATE_PENDING);
 
+        r = link_drop_foreign_config(link);
+        if (r < 0)
+                return r;
+
         r = link_set_bridge_fdb(link);
         if (r < 0)
                 return r;