zebra: fix detection of VRF misconfiguration

The netlink_vrf_change() function is called both when a VRF device
is created in the Linux kernel and when it is activated. This
commit changes this function to perform the VRF misconfiguration
detection only when the VRF device is created, as doing the check
twice would cause a false positive followed by a hard failure (not
to mention the double check is unnecessary since the VRF table ID
can't change once the device is created).

Fixes #6319.

Signed-off-by: Renato Westphal <renato@opensourcerouting.org>

diff --git a/zebra/if_netlink.c b/zebra/if_netlink.c
index 17b6edfed04978e972621a30cf2347bf53e3ac6f..429bb968a52ff7364699fc6509c9b199b246cbf4 100644 (file)
--- a/zebra/if_netlink.c
+++ b/zebra/if_netlink.c
@@ -310,22 +310,25 @@ static void netlink_vrf_change(struct nlmsghdr *h, struct rtattr *tb,
        nl_table_id = *(uint32_t *)RTA_DATA(attr[IFLA_VRF_TABLE]);
 
        if (h->nlmsg_type == RTM_NEWLINK) {
-               vrf_id_t exist_id;
-
                if (IS_ZEBRA_DEBUG_KERNEL)
                        zlog_debug("RTM_NEWLINK for VRF %s(%u) table %u", name,
                                   ifi->ifi_index, nl_table_id);
 
-               exist_id = vrf_lookup_by_table(nl_table_id, ns_id);
-               if (exist_id != VRF_DEFAULT) {
-                       vrf = vrf_lookup_by_id(exist_id);
+               if (!vrf_lookup_by_id((vrf_id_t)ifi->ifi_index)) {
+                       vrf_id_t exist_id;
 
-                       flog_err(
-                               EC_ZEBRA_VRF_MISCONFIGURED,
-                               "VRF %s id %u table id overlaps existing vrf %s, misconfiguration exiting",
-                               name, ifi->ifi_index, vrf->name);
-                       exit(-1);
+                       exist_id = vrf_lookup_by_table(nl_table_id, ns_id);
+                       if (exist_id != VRF_DEFAULT) {
+                               vrf = vrf_lookup_by_id(exist_id);
+
+                               flog_err(
+                                       EC_ZEBRA_VRF_MISCONFIGURED,
+                                       "VRF %s id %u table id overlaps existing vrf %s, misconfiguration exiting",
+                                       name, ifi->ifi_index, vrf->name);
+                               exit(-1);
+                       }
                }
+
                /*
                 * vrf_get is implied creation if it does not exist
                 */