From: Yuyang Huang <yuyanghuang@google.com>
Date: Fri, 23 May 2025 03:25:18 +0000 (+0900)
Subject: iproute2: bugfix - restore ip monitor backward compatibility.
X-Git-Tag: v6.15.0~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=969817ce1ddb1aab375d74d0eee6454c13656f84;p=thirdparty%2Fiproute2.git

iproute2: bugfix - restore ip monitor backward compatibility.

The current ip monitor implementation fails on older kernels that lack
newer RTNLGRP_* definitions. As ip monitor is expected to maintain
backward compatibility, this commit updates the code to check if errno
is not EINVAL when rtnl_add_nl_group() fails. This change restores ip
monitor's backward compatibility with older kernel versions.

Cc: David Ahern <dsahern@kernel.org>
Cc: Luca Boccassi <bluca@debian.org>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>

Reported-by: Adel Belhouane <bugs.a.b@free.fr>
Fixes: 19514606dce3 ("iproute2: add 'ip monitor maddress' support")
Closes: https://lore.kernel.org/netdev/CADXeF1GgJ_1tee3hc7gca2Z21Lyi3mzxq52sSfMg3mFQd2rGWQ@mail.gmail.com/T/#t
Signed-off-by: Yuyang Huang <yuyanghuang@google.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---

diff --git a/ip/ipmonitor.c b/ip/ipmonitor.c
index b890b4d0..1f4e860f 100644
--- a/ip/ipmonitor.c
+++ b/ip/ipmonitor.c
@@ -5,6 +5,7 @@
  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  */
 
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -328,38 +329,46 @@ int do_ipmonitor(int argc, char **argv)
 
 	if (lmask & IPMON_LNEXTHOP &&
 	    rtnl_add_nl_group(&rth, RTNLGRP_NEXTHOP) < 0) {
-		fprintf(stderr, "Failed to add nexthop group to list\n");
-		exit(1);
+		if (errno != EINVAL) {
+			fprintf(stderr, "Failed to add nexthop group to list\n");
+			exit(1);
+		}
 	}
 
 	if (lmask & IPMON_LSTATS &&
 	    rtnl_add_nl_group(&rth, RTNLGRP_STATS) < 0 &&
 	    nmask & IPMON_LSTATS) {
-		fprintf(stderr, "Failed to add stats group to list\n");
-		exit(1);
+		if (errno != EINVAL) {
+			fprintf(stderr, "Failed to add stats group to list\n");
+			exit(1);
+		}
 	}
 
 	if (lmask & IPMON_LMADDR) {
 		if ((!preferred_family || preferred_family == AF_INET) &&
 		    rtnl_add_nl_group(&rth, RTNLGRP_IPV4_MCADDR) < 0) {
-			fprintf(stderr,
-				"Failed to add ipv4 mcaddr group to list\n");
-			exit(1);
+			if (errno != EINVAL) {
+				fprintf(stderr, "Failed to add ipv4 mcaddr group to list\n");
+				exit(1);
+			}
 		}
 		if ((!preferred_family || preferred_family == AF_INET6) &&
 		    rtnl_add_nl_group(&rth, RTNLGRP_IPV6_MCADDR) < 0) {
-			fprintf(stderr,
-				"Failed to add ipv6 mcaddr group to list\n");
-			exit(1);
+			if (errno != EINVAL) {
+				fprintf(stderr,
+					"Failed to add ipv6 mcaddr group to list\n");
+				exit(1);
+			}
 		}
 	}
 
 	if (lmask & IPMON_LACADDR) {
 		if ((!preferred_family || preferred_family == AF_INET6) &&
 		    rtnl_add_nl_group(&rth, RTNLGRP_IPV6_ACADDR) < 0) {
-			fprintf(stderr,
-				"Failed to add ipv6 acaddr group to list\n");
-			exit(1);
+			if (errno != EINVAL) {
+				fprintf(stderr, "Failed to add ipv6 acaddr group to list\n");
+				exit(1);
+			}
 		}
 	}