From d2895063305712cd9e5d7f4361f9343bf3b3f00b Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Mon, 12 Jul 2021 21:23:41 +0900
Subject: [PATCH] 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 #20203.

(cherry picked from commit 176b8be10ffce2f8c1fc931a37904a528057016f)

Conflict:NA
Reference:https://github.com/systemd/systemd/commit/d2895063305712cd9e5d7f4361f9343bf3b3f00b
---
 src/network/networkd-link.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 9421ce1aa6..d58b700050 100644
--- a/src/network/networkd-link.c
+++ b/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>
@@ -21,6 +22,7 @@
 #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"
@@ -2161,6 +2163,7 @@ 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;
 
@@ -2177,6 +2180,16 @@ 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);
-- 
2.33.0