core: fix nm_netns_ip_route_ecmp_commit() to return regular single-hop routeth/tmp7

nm_netns_ip_route_ecmp_commit() returns the ECMP routes that didn't find
a merge-partner. It expects NML3Cfg to configure such routes in
platform.

Note that these routes have a positive "weight", which was used for
tracking the ECMP information in NML3Cfg and NMNetns.

But in kernel, single-hop routes don't have a weight. All routes in
NMPlatform will have a zero weight. While it somewhat works to call
nm_platform_ip_route_add() with a single-hop route of non-zero weight,
the result will be a different(!) route. This means for example that
nm_platform_ip_route_sync() will search the NMPlatform cache for whether
the routes exist, but in the cache single-hop routes with positive weight
never exist.

The proper solution is that nm_netns_ip_route_ecmp_commit() does not
tell NML3Cfg to add a route, that cannot be added. Instead, it must
first normalize the weight to zero, to have a "regular" single-hop
route.

Fixes: 5b5ce4268211 ('nm-netns: track ECMP routes')

1 files changed, 26 insertions, 1 deletions

diff --git a/src/core/nm-netns.c b/src/core/nm-netns.c
index 7c279cafc3..e0bd19bbe0 100644
--- a/src/core/nm-netns.c
+++ b/src/core/nm-netns.c
@@ -916,6 +916,8 @@ nm_netns_ip_route_ecmp_commit(NMNetns    *self,
         }
 
         if (route->n_nexthops <= 1) {
+            NMPObject *route_clone;
+
             /* This is a single hop route. Return it to the caller. */
             if (!*out_singlehop_routes) {
                 /* Note that the returned array does not own a reference. This
@@ -924,7 +926,30 @@ nm_netns_ip_route_ecmp_commit(NMNetns    *self,
                 *out_singlehop_routes =
                     g_ptr_array_new_with_free_func((GDestroyNotify) nmp_object_unref);
             }
-            g_ptr_array_add(*out_singlehop_routes, (gpointer) nmp_object_ref(route_obj));
+
+            /* We have here a IPv4 single-hop route. For internal tracking purposes,
+             * this route has a positive "weight" (which was used to mark it as a candidate
+             * for ECMP merging). Now we want to return this route to NML3Cfg and add it
+             * as regular single-hop routes.
+             *
+             * A single-hop route in kernel always has a "weight" of zero. This route
+             * cannot be added as-is. Well, if we would, then the result would be
+             * a different(!) route (with a zero "weight").
+             *
+             * Anticipate that and normalize the route now to be a regular single-hop
+             * route (with weight zero). nm_platform_ip_route_normalize() does that.
+             * We really want to return a regular route here, not the route with a positive
+             * weight that exists for internal tracking purposes.
+             */
+            nm_assert(route_obj->ip4_route.weight > 0u);
+            nm_assert(NMP_OBJECT_GET_TYPE(route_obj) == NMP_OBJECT_TYPE_IP4_ROUTE);
+
+            route_clone = nmp_object_clone(route_obj, FALSE);
+            nm_platform_ip_route_normalize(AF_INET,
+                                           NMP_OBJECT_CAST_IP_ROUTE(route_clone),
+                                           NMP_IP_ROUTE_NORMALIZE_FLAGS_NONE);
+            g_ptr_array_add(*out_singlehop_routes, route_clone);
+
             if (changed) {
                 _LOGT("ecmp-route: single-hop %s",
                       nmp_object_to_string(route_obj,