ipv6: introduce idgen_delay and idgen_retries knobs

This is specified by RFC 7217.

Cc: Erik Kline <ek@google.com>
Cc: Fernando Gont <fgont@si6networks.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: YOSHIFUJI Hideaki/吉藤英明 <hideaki.yoshifuji@miraclelinux.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netns/ipv6.h

@@ -32,6 +32,8 @@ struct netns_sysctl_ipv6 {
 	int icmpv6_time;
 	int anycast_src_echo_reply;
 	int fwmark_reflect;
+	int idgen_retries;
+	int idgen_delay;
 };
 
 struct netns_ipv6 {

net/ipv6/addrconf.c

@@ -1712,6 +1712,7 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 {
 	struct in6_addr addr;
 	struct inet6_dev *idev = ifp->idev;
+	struct net *net = dev_net(ifp->idev->dev);
 
 	if (addrconf_dad_end(ifp)) {
 		in6_ifa_put(ifp);
@@ -1730,11 +1731,9 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 		struct inet6_ifaddr *ifp2;
 		u32 valid_lft, preferred_lft;
 		int pfxlen = ifp->prefix_len;
-		const unsigned int idgen_retries = 3;
-		const unsigned int idgen_delay = 1 * HZ;
 		int retries = ifp->stable_privacy_retry + 1;
 
-		if (retries > idgen_retries) {
+		if (retries > net->ipv6.sysctl.idgen_retries) {
 			net_info_ratelimited("%s: privacy stable address generation failed because of DAD conflicts!\n",
 					     ifp->idev->dev->name);
 			goto errdad;
@@ -1769,7 +1768,7 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 		ifp2->state = INET6_IFADDR_STATE_PREDAD;
 		spin_unlock_bh(&ifp2->lock);
 
-		addrconf_mod_dad_work(ifp2, idgen_delay);
+		addrconf_mod_dad_work(ifp2, net->ipv6.sysctl.idgen_delay);
 		in6_ifa_put(ifp2);
 lock_errdad:
 		spin_lock_bh(&ifp->lock);
@@ -2899,8 +2898,6 @@ static int ipv6_generate_stable_address(struct in6_addr *address,
 					u8 dad_count,
 					const struct inet6_dev *idev)
 {
-	static const int idgen_retries = 3;
-
 	static DEFINE_SPINLOCK(lock);
 	static __u32 digest[SHA_DIGEST_WORDS];
 	static __u32 workspace[SHA_WORKSPACE_WORDS];
@@ -2950,7 +2947,7 @@ retry:
 
 	if (ipv6_reserved_interfaceid(temp)) {
 		dad_count++;
-		if (dad_count > idgen_retries)
+		if (dad_count > dev_net(idev->dev)->ipv6.sysctl.idgen_retries)
 			return -1;
 		goto retry;
 	}

net/ipv6/af_inet6.c

@@ -766,6 +766,8 @@ static int __net_init inet6_net_init(struct net *net)
 	net->ipv6.sysctl.icmpv6_time = 1*HZ;
 	net->ipv6.sysctl.flowlabel_consistency = 1;
 	net->ipv6.sysctl.auto_flowlabels = 0;
+	net->ipv6.sysctl.idgen_retries = 3;
+	net->ipv6.sysctl.idgen_delay = 1 * HZ;
 	atomic_set(&net->ipv6.fib6_sernum, 1);
 
 	err = ipv6_init_mibs(net);

net/ipv6/sysctl_net_ipv6.c

@@ -54,6 +54,20 @@ static struct ctl_table ipv6_table_template[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "idgen_retries",
+		.data		= &init_net.ipv6.sysctl.idgen_retries,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "idgen_delay",
+		.data		= &init_net.ipv6.sysctl.idgen_delay,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+	},
 	{ }
 };
 
@@ -93,6 +107,8 @@ static int __net_init ipv6_sysctl_net_init(struct net *net)
 	ipv6_table[2].data = &net->ipv6.sysctl.flowlabel_consistency;
 	ipv6_table[3].data = &net->ipv6.sysctl.auto_flowlabels;
 	ipv6_table[4].data = &net->ipv6.sysctl.fwmark_reflect;
+	ipv6_table[5].data = &net->ipv6.sysctl.idgen_retries;
+	ipv6_table[6].data = &net->ipv6.sysctl.idgen_delay;
 
 	ipv6_route_table = ipv6_route_sysctl_init(net);
 	if (!ipv6_route_table)