[IPV4]: Add per-device sysctl to force IGMP version.

include/linux/inetdevice.h

@@ -21,6 +21,7 @@ struct ipv4_devconf
 	int	medium_id;
 	int	no_xfrm;
 	int	no_policy;
+	int	force_igmp_version;
 	void	*sysctl;
 };
 

include/linux/sysctl.h

@@ -360,6 +360,7 @@ enum
 	NET_IPV4_CONF_MEDIUM_ID=14,
 	NET_IPV4_CONF_NOXFRM=15,
 	NET_IPV4_CONF_NOPOLICY=16,
+	NET_IPV4_CONF_FORCE_IGMP_VERSION=17,
 };
 
 /* /proc/sys/net/ipv4/netfilter */

net/ipv4/devinet.c

@@ -1132,7 +1132,7 @@ int ipv4_doint_and_flush_strategy(ctl_table *table, int *name, int nlen,
 
 static struct devinet_sysctl_table {
 	struct ctl_table_header *sysctl_header;
-	ctl_table		devinet_vars[17];
+	ctl_table		devinet_vars[18];
 	ctl_table		devinet_dev[2];
 	ctl_table		devinet_conf_dir[2];
 	ctl_table		devinet_proto_dir[2];
@@ -1269,6 +1269,15 @@ static struct devinet_sysctl_table {
 			.proc_handler	= &ipv4_doint_and_flush,
 			.strategy	= &ipv4_doint_and_flush_strategy,
 		},
+		{
+			.ctl_name	= NET_IPV4_CONF_FORCE_IGMP_VERSION,
+			.procname	= "force_igmp_version",
+			.data		= &ipv4_devconf.force_igmp_version,
+			.maxlen		= sizeof(int),
+			.mode		= 0644,
+			.proc_handler	= &ipv4_doint_and_flush,
+			.strategy	= &ipv4_doint_and_flush_strategy,
+		},
 	},
 	.devinet_dev = {
 		{

net/ipv4/igmp.c

@@ -126,10 +126,14 @@
  * contradict to specs provided this delay is small enough.
  */
 
-#define IGMP_V1_SEEN(in_dev) ((in_dev)->mr_v1_seen && \
-		time_before(jiffies, (in_dev)->mr_v1_seen))
-#define IGMP_V2_SEEN(in_dev) ((in_dev)->mr_v2_seen && \
-		time_before(jiffies, (in_dev)->mr_v2_seen))
+#define IGMP_V1_SEEN(in_dev) (ipv4_devconf.force_igmp_version == 1 || \
+		(in_dev)->cnf.force_igmp_version == 1 || \
+		((in_dev)->mr_v1_seen && \
+		time_before(jiffies, (in_dev)->mr_v1_seen)))
+#define IGMP_V2_SEEN(in_dev) (ipv4_devconf.force_igmp_version == 2 || \
+		(in_dev)->cnf.force_igmp_version == 2 || \
+		((in_dev)->mr_v2_seen && \
+		time_before(jiffies, (in_dev)->mr_v2_seen)))
 
 static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im);
 static void igmpv3_del_delrec(struct in_device *in_dev, __u32 multiaddr);