network: check the received interface name is actually new

For some reasons I do not know, on interface renaming, kernel once send
netlink message with old interface name, and then send with new name.
If eth0 is renamed, and then new interface appears as eth0, then the
message with the old name 'eth0' makes the interface enters failed
state.

To ignore such invalid(?) rename event messages, let's confirm the
received interface name.

Fixes systemd#20203.

src/network/networkd-link.c

@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <net/if.h>
 #include <netinet/in.h>
 #include <linux/if.h>
 #include <linux/if_arp.h>
@@ -20,6 +21,7 @@
 #include "ethtool-util.h"
 #include "fd-util.h"
 #include "fileio.h"
+#include "format-util.h"
 #include "fs-util.h"
 #include "ipvlan.h"
 #include "missing_network.h"
@@ -2160,6 +2162,7 @@ static int link_update_alternative_names(Link *link, sd_netlink_message *message
 }
 
 static int link_update_name(Link *link, sd_netlink_message *message) {
+        char ifname_from_index[IF_NAMESIZE + 1];
         const char *ifname;
         int r;
 
@@ -2176,6 +2179,16 @@ static int link_update_name(Link *link, sd_netlink_message *message) {
         if (streq(ifname, link->ifname))
                 return 0;
 
+        if (!format_ifname(link->ifindex, ifname_from_index))
+                return log_link_debug_errno(link, SYNTHETIC_ERRNO(ENXIO), "Could not get interface name for index %i.", link->ifindex);
+
+        if (!streq(ifname, ifname_from_index)) {
+                log_link_debug(link, "New interface name '%s' received from the kernel does not correspond "
+                               "with the name currently configured on the actual interface '%s'. Ignoring.",
+                               ifname, ifname_from_index);
+                return 0;
+        }
+
         log_link_info(link, "Interface name change detected, renamed to %s.", ifname);
 
         hashmap_remove(link->manager->links_by_name, link->ifname);