[IPV6]: Add sysctl to force MLD version.

include/linux/ipv6.h

@@ -136,6 +136,7 @@ struct ipv6_devconf {
 	__s32		rtr_solicits;
 	__s32		rtr_solicit_interval;
 	__s32		rtr_solicit_delay;
+	__s32		force_mld_version;
 #ifdef CONFIG_IPV6_PRIVACY
 	__s32		use_tempaddr;
 	__s32		temp_valid_lft;
@@ -165,6 +166,7 @@ enum {
 	DEVCONF_REGEN_MAX_RETRY,
 	DEVCONF_MAX_DESYNC_FACTOR,
 	DEVCONF_MAX_ADDRESSES,
+	DEVCONF_FORCE_MLD_VERSION,
 	DEVCONF_MAX
 };
 

include/linux/sysctl.h

@@ -424,7 +424,8 @@ enum {
 	NET_IPV6_TEMP_PREFERED_LFT=13,
 	NET_IPV6_REGEN_MAX_RETRY=14,
 	NET_IPV6_MAX_DESYNC_FACTOR=15,
-	NET_IPV6_MAX_ADDRESSES=16
+	NET_IPV6_MAX_ADDRESSES=16,
+	NET_IPV6_FORCE_MLD_VERSION=17
 };
 
 /* /proc/sys/net/ipv6/icmp */

net/ipv6/addrconf.c

@@ -149,6 +149,7 @@ struct ipv6_devconf ipv6_devconf = {
 	.accept_ra		= 1,
 	.accept_redirects	= 1,
 	.autoconf		= 1,
+	.force_mld_version	= 0,
 	.dad_transmits		= 1,
 	.rtr_solicits		= MAX_RTR_SOLICITATIONS,
 	.rtr_solicit_interval	= RTR_SOLICITATION_INTERVAL,
@@ -2739,6 +2740,7 @@ static void inline ipv6_store_devconf(struct ipv6_devconf *cnf,
 	array[DEVCONF_RTR_SOLICITS] = cnf->rtr_solicits;
 	array[DEVCONF_RTR_SOLICIT_INTERVAL] = cnf->rtr_solicit_interval;
 	array[DEVCONF_RTR_SOLICIT_DELAY] = cnf->rtr_solicit_delay;
+	array[DEVCONF_FORCE_MLD_VERSION] = cnf->force_mld_version;
 #ifdef CONFIG_IPV6_PRIVACY
 	array[DEVCONF_USE_TEMPADDR] = cnf->use_tempaddr;
 	array[DEVCONF_TEMP_VALID_LFT] = cnf->temp_valid_lft;
@@ -3042,7 +3044,7 @@ static int addrconf_sysctl_forward_strategy(ctl_table *table,
 static struct addrconf_sysctl_table
 {
 	struct ctl_table_header *sysctl_header;
-	ctl_table addrconf_vars[17];
+	ctl_table addrconf_vars[18];
 	ctl_table addrconf_dev[2];
 	ctl_table addrconf_conf_dir[2];
 	ctl_table addrconf_proto_dir[2];
@@ -3133,6 +3135,14 @@ static struct addrconf_sysctl_table
          		.proc_handler	=	&proc_dointvec_jiffies,
 			.strategy	=	&sysctl_jiffies,
 		},
+		{
+			.ctl_name	=	NET_IPV6_FORCE_MLD_VERSION,
+			.procname	=	"force_mld_version",
+         		.data		=	&ipv6_devconf.force_mld_version,
+			.maxlen		=	sizeof(int),
+			.mode		=	0644,
+         		.proc_handler	=	&proc_dointvec,
+		},
 #ifdef CONFIG_IPV6_PRIVACY
 		{
 			.ctl_name	=	NET_IPV6_USE_TEMPADDR,

net/ipv6/mcast.c

@@ -152,8 +152,10 @@ int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml,
 #define IGMP6_UNSOLICITED_IVAL	(10*HZ)
 #define MLD_QRV_DEFAULT		2
 
-#define MLD_V1_SEEN(idev) ((idev)->mc_v1_seen && \
-		time_before(jiffies, (idev)->mc_v1_seen))
+#define MLD_V1_SEEN(idev) (ipv6_devconf.force_mld_version == 1 || \
+		(idev)->cnf.force_mld_version == 1 || \
+		((idev)->mc_v1_seen && \
+		time_before(jiffies, (idev)->mc_v1_seen)))
 
 #define MLDV2_MASK(value, nb) ((nb)>=32 ? (value) : ((1<<(nb))-1) & (value))
 #define MLDV2_EXP(thresh, nbmant, nbexp, value) \