From 289e1e5e00b3e6f655edf0ab83ef8c0b86a6c8bb Mon Sep 17 00:00:00 2001 From: Donald Sharp Date: Mon, 14 Oct 2024 11:25:32 -0400 Subject: [PATCH] zebra: Prevent a kernel route from being there when a connected should There exists a series of events where a kernel route is learned first( that happens to be exactly what a connected route should be ) and FRR ends up with both a kernel route and a connected route, leaving us in a very strange spot. This code change just mirrors the existing code of if there is a connected route drop the kernel route. Here we just do the reverse, if we have a kernel route already and a connected should be created, remove the kernel and keep the connected. Signed-off-by: Donald Sharp (cherry picked from commit 74e25198e74c4066b630515d2971c3c9381d70f2) --- zebra/connected.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/zebra/connected.c b/zebra/connected.c index 404f892f6e5c..5c72de7ab585 100644 --- a/zebra/connected.c +++ b/zebra/connected.c @@ -176,6 +176,40 @@ static void connected_update(struct interface *ifp, struct connected *ifc) connected_announce(ifp, ifc); } +/* + * This function goes through and handles the deletion of a kernel route that happened + * to be the exact same as the connected route, so that the connected route wins. + * This can happen during processing if we happen to receive events in a slightly + * unexpected order. This is similiar to code in the other direction where if we + * have a kernel route don't install it if it perfectly matches a connected route. + */ +static void connected_remove_kernel_for_connected(afi_t afi, safi_t safi, struct zebra_vrf *zvrf, + struct prefix *p, struct nexthop *nh) +{ + struct route_node *rn; + struct route_entry *re; + rib_dest_t *dest; + struct route_table *table = zebra_vrf_table(afi, SAFI_UNICAST, zvrf->vrf->vrf_id); + + rn = route_node_match(table, p); + if (!rn) + return; + + if (!prefix_same(&rn->p, p)) + return; + + dest = rib_dest_from_rnode(rn); + if (!dest || !dest->selected_fib) + return; + + re = dest->selected_fib; + if (re->type != ZEBRA_ROUTE_KERNEL) + return; + + rib_delete(afi, SAFI_UNICAST, zvrf->vrf->vrf_id, ZEBRA_ROUTE_KERNEL, 0, 0, p, NULL, nh, 0, + zvrf->table_id, 0, 0, false); +} + /* Called from if_up(). */ void connected_up(struct interface *ifp, struct connected *ifc) { @@ -283,10 +317,13 @@ void connected_up(struct interface *ifp, struct connected *ifc) } if (!CHECK_FLAG(ifc->flags, ZEBRA_IFA_NOPREFIXROUTE)) { + connected_remove_kernel_for_connected(afi, SAFI_UNICAST, zvrf, &p, &nh); + rib_add(afi, SAFI_UNICAST, zvrf->vrf->vrf_id, ZEBRA_ROUTE_CONNECT, 0, flags, &p, NULL, &nh, 0, zvrf->table_id, metric, 0, 0, 0, false); + connected_remove_kernel_for_connected(afi, SAFI_MULTICAST, zvrf, &p, &nh); rib_add(afi, SAFI_MULTICAST, zvrf->vrf->vrf_id, ZEBRA_ROUTE_CONNECT, 0, flags, &p, NULL, &nh, 0, zvrf->table_id, metric, 0, 0, 0, false);