network: Add support to ignore foreign routes

man/networkd.conf.xml

@@ -61,6 +61,15 @@
         <listitem><para>Specifies the time interval to calculate the traffic speed of each interface.
         If <varname>SpeedMeter=no</varname>, the value is ignored. Defaults to 10sec.</para></listitem>
       </varlistentry>
+
+      <varlistentry>
+        <term><varname>ManageForeignRoutes=</varname></term>
+        <listitem><para>A boolean. When true, <command>systemd-networkd</command> will store any routes
+        configured by other tools in its memory. When false, <command>systemd-networkd</command> will
+        not manage the foreign routes, thus they are kept even if <varname>KeepConfiguration=</varname>
+        is false. Defaults to yes.</para></listitem>
+      </varlistentry>
+
     </variablelist>
   </refsect1>
 

src/network/networkd-gperf.gperf

@@ -20,5 +20,6 @@ struct ConfigPerfItem;
 %%
 Network.SpeedMeter,            config_parse_bool,                      0,          offsetof(Manager, use_speed_meter)
 Network.SpeedMeterIntervalSec, config_parse_sec,                       0,          offsetof(Manager, speed_meter_interval_usec)
+Network.ManageForeignRoutes,   config_parse_bool,                      0,          offsetof(Manager, manage_foreign_routes)
 DHCP.DUIDType,                 config_parse_duid_type,                 0,          offsetof(Manager, duid)
 DHCP.DUIDRawData,              config_parse_duid_rawdata,              0,          offsetof(Manager, duid)

src/network/networkd-manager.c

@@ -494,7 +494,8 @@ int manager_rtnl_process_route(sd_netlink *rtnl, sd_netlink_message *message, vo
 
                 log_link_debug(link,
                                "%s route: dst: %s%s, src: %s, gw: %s, prefsrc: %s, scope: %s, table: %s, proto: %s, type: %s",
-                               type == RTM_DELROUTE ? "Forgetting" : route ? "Received remembered" : "Remembering",
+                               (!route && !link->manager->manage_foreign_routes) || type == RTM_DELROUTE ? "Forgetting" :
+                               route ? "Received remembered" : "Remembering",
                                strna(buf_dst), strempty(buf_dst_prefixlen),
                                strna(buf_src), strna(buf_gw), strna(buf_prefsrc),
                                format_route_scope(tmp->scope, buf_scope, sizeof buf_scope),
@@ -505,7 +506,7 @@ int manager_rtnl_process_route(sd_netlink *rtnl, sd_netlink_message *message, vo
 
         switch (type) {
         case RTM_NEWROUTE:
-                if (!route) {
+                if (!route && link->manager->manage_foreign_routes) {
                         /* A route appeared that we did not request */
                         r = route_add_foreign(link, tmp, &route);
                         if (r < 0) {
@@ -1747,6 +1748,7 @@ int manager_new(Manager **ret) {
 
         *m = (Manager) {
                 .speed_meter_interval_usec = SPEED_METER_DEFAULT_TIME_INTERVAL,
+                .manage_foreign_routes = true,
         };
 
         m->state_file = strdup("/run/systemd/netif/state");

src/network/networkd-manager.h

@@ -30,6 +30,7 @@ struct Manager {
         bool enumerating:1;
         bool dirty:1;
         bool restarting:1;
+        bool manage_foreign_routes;
 
         Set *dirty_links;
 

src/network/networkd.conf

@@ -14,6 +14,7 @@
 [Network]
 #SpeedMeter=no
 #SpeedMeterIntervalSec=10sec
+#ManageForeignRoutes=yes
 
 [DHCP]
 #DUIDType=vendor