[PATCH net-next v3 1/2] ipv6: add sysctl_mld_qrv to configure query robustness variable

[PATCH net-next v3 1/2] ipv6: add sysctl_mld_qrv to configure query robustness variable

[Hannes Frederic Sowa]

This patch adds a new sysctl_mld_qrv knob to configure the mldv1/v2 query
robustness variable. It specifies how many retransmit of unsolicited mld
retransmit should happen. Admins might want to tune this on lossy links.

Also reset mld state on interface down/up, so we pick up new sysctl
settings during interface up event.

IPv6 certification requests this knob to be available.

I didn't make this knob netns specific, as it is mostly a setting in a
physical environment and should be per host.

Cc: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
v2) no changes to original version

v3) - enhance Documentation/networking/ip-sysctl.txt with sysctl limits
    - fix clamping of remotely received mld_qrv value

 Documentation/networking/ip-sysctl.txt |  5 +++++
 include/net/ipv6.h                     |  1 +
 net/ipv6/mcast.c                       | 25 +++++++++++++++----------
 net/ipv6/sysctl_net_ipv6.c             | 10 ++++++++++
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 3cce8ea..cfc71ac 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1152,6 +1152,11 @@ anycast_src_echo_reply - BOOLEAN
 	FALSE: disabled
 	Default: FALSE
 
+mld_qrv - INTEGER
+	Controls the MLD query robustness variable (see RFC3810 9.1).
+	Default: 2 (as specified by RFC3810 9.1)
+	Minimum: 1 (as specified by RFC6636 4.5)
+
 IPv6 Fragmentation:
 
 ip6frag_high_thresh - INTEGER
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index a2db816..7e247e9 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -121,6 +121,7 @@ struct frag_hdr {
 
 /* sysctls */
 extern int sysctl_mld_max_msf;
+extern int sysctl_mld_qrv;
 
 #define _DEVINC(net, statname, modifier, idev, field)			\
 ({									\
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 7088179..6491942 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -121,6 +121,7 @@ static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml,
 #define IPV6_MLD_MAX_MSF	64
 
 int sysctl_mld_max_msf __read_mostly = IPV6_MLD_MAX_MSF;
+int sysctl_mld_qrv __read_mostly = MLD_QRV_DEFAULT;
 
 /*
  *	socket join on multicast group
@@ -1191,15 +1192,16 @@ static void mld_update_qrv(struct inet6_dev *idev,
 	 * and SHOULD NOT be one. Catch this here if we ever run
 	 * into such a case in future.
 	 */
+	const int min_qrv = min(MLD_QRV_DEFAULT, sysctl_mld_qrv);
 	WARN_ON(idev->mc_qrv == 0);
 
 	if (mlh2->mld2q_qrv > 0)
 		idev->mc_qrv = mlh2->mld2q_qrv;
 
-	if (unlikely(idev->mc_qrv < 2)) {
+	if (unlikely(idev->mc_qrv < min_qrv)) {
 		net_warn_ratelimited("IPv6: MLD: clamping QRV from %u to %u!\n",
-				     idev->mc_qrv, MLD_QRV_DEFAULT);
-		idev->mc_qrv = MLD_QRV_DEFAULT;
+				     idev->mc_qrv, min_qrv);
+		idev->mc_qrv = min_qrv;
 	}
 }
 
@@ -2478,6 +2480,14 @@ void ipv6_mc_down(struct inet6_dev *idev)
 	mld_clear_delrec(idev);
 }
 
+static void ipv6_mc_reset(struct inet6_dev *idev)
+{
+	idev->mc_qrv = sysctl_mld_qrv;
+	idev->mc_qi = MLD_QI_DEFAULT;
+	idev->mc_qri = MLD_QRI_DEFAULT;
+	idev->mc_v1_seen = 0;
+	idev->mc_maxdelay = unsolicited_report_interval(idev);
+}
 
 /* Device going up */
 
@@ -2488,6 +2498,7 @@ void ipv6_mc_up(struct inet6_dev *idev)
 	/* Install multicast list, except for all-nodes (already installed) */
 
 	read_lock_bh(&idev->lock);
+	ipv6_mc_reset(idev);
 	for (i = idev->mc_list; i; i = i->next)
 		igmp6_group_added(i);
 	read_unlock_bh(&idev->lock);
@@ -2508,13 +2519,7 @@ void ipv6_mc_init_dev(struct inet6_dev *idev)
 			(unsigned long)idev);
 	setup_timer(&idev->mc_dad_timer, mld_dad_timer_expire,
 		    (unsigned long)idev);
-
-	idev->mc_qrv = MLD_QRV_DEFAULT;
-	idev->mc_qi = MLD_QI_DEFAULT;
-	idev->mc_qri = MLD_QRI_DEFAULT;
-
-	idev->mc_maxdelay = unsolicited_report_interval(idev);
-	idev->mc_v1_seen = 0;
+	ipv6_mc_reset(idev);
 	write_unlock_bh(&idev->lock);
 }
 
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index 0c56c93..c5c10fa 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -16,6 +16,8 @@
 #include <net/addrconf.h>
 #include <net/inet_frag.h>
 
+static int one = 1;
+
 static struct ctl_table ipv6_table_template[] = {
 	{
 		.procname	= "bindv6only",
@@ -63,6 +65,14 @@ static struct ctl_table ipv6_rotable[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+	{
+		.procname	= "mld_qrv",
+		.data		= &sysctl_mld_qrv,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &one
+	},
 	{ }
 };
 
-- 
1.9.3

[PATCH net-next v3 2/2] ipv4: implement igmp_qrv sysctl to tune igmp robustness variable

[Hannes Frederic Sowa]

As in IPv6 people might increase the igmp query robustness variable to
make sure unsolicited state change reports aren't lost on the network. Add
and document this new knob to igmp code.

RFCs allow tuning this parameter back to first IGMP RFC, so we also use
this setting for all counters, including source specific multicast.

Also take over sysctl value when upping the interface and don't reuse
the last one seen on the interface.

Cc: Flavio Leitner <fbl@redhat.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
v2) Guard sysctl_igmp_qrv with CONFIG_IP_MULTICAST so we don't use
    IGMP_Query_Robustness_Variable without it being defined.

v3) document minimum and default values of igmp_qrv

 Documentation/networking/ip-sysctl.txt |  5 +++++
 include/linux/igmp.h                   |  1 +
 net/ipv4/igmp.c                        | 31 +++++++++++++++----------------
 net/ipv4/sysctl_net_ipv4.c             | 10 ++++++++++
 4 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index cfc71ac..db2383c 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -844,6 +844,11 @@ igmp_max_memberships - INTEGER
 
 	conf/all/*	  is special, changes the settings for all interfaces
 
+igmp_qrv - INTEGER
+	 Controls the IGMP query robustness variable (see RFC2236 8.1).
+	 Default: 2 (as specified by RFC2236 8.1)
+	 Minimum: 1 (as specified by RFC6636 4.5)
+
 log_martians - BOOLEAN
 	Log packets with impossible addresses to kernel log.
 	log_martians for the interface will be enabled if at least one of
diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index f47550d..2c677af 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -39,6 +39,7 @@ static inline struct igmpv3_query *
 
 extern int sysctl_igmp_max_memberships;
 extern int sysctl_igmp_max_msf;
+extern int sysctl_igmp_qrv;
 
 struct ip_sf_socklist {
 	unsigned int		sl_max;
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 890c425..4146153 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -117,7 +117,7 @@
 #define IGMP_V2_Unsolicited_Report_Interval	(10*HZ)
 #define IGMP_V3_Unsolicited_Report_Interval	(1*HZ)
 #define IGMP_Query_Response_Interval		(10*HZ)
-#define IGMP_Unsolicited_Report_Count		2
+#define IGMP_Query_Robustness_Variable		2
 
 
 #define IGMP_Initial_Report_Delay		(1)
@@ -756,8 +756,7 @@ static void igmp_ifc_event(struct in_device *in_dev)
 {
 	if (IGMP_V1_SEEN(in_dev) || IGMP_V2_SEEN(in_dev))
 		return;
-	in_dev->mr_ifc_count = in_dev->mr_qrv ? in_dev->mr_qrv :
-		IGMP_Unsolicited_Report_Count;
+	in_dev->mr_ifc_count = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 	igmp_ifc_start_timer(in_dev, 1);
 }
 
@@ -1086,8 +1085,7 @@ static void igmpv3_add_delrec(struct in_device *in_dev, struct ip_mc_list *im)
 	pmc->interface = im->interface;
 	in_dev_hold(in_dev);
 	pmc->multiaddr = im->multiaddr;
-	pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-		IGMP_Unsolicited_Report_Count;
+	pmc->crcount = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 	pmc->sfmode = im->sfmode;
 	if (pmc->sfmode == MCAST_INCLUDE) {
 		struct ip_sf_list *psf;
@@ -1226,8 +1224,7 @@ static void igmp_group_added(struct ip_mc_list *im)
 	}
 	/* else, v3 */
 
-	im->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-		IGMP_Unsolicited_Report_Count;
+	im->crcount = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 	igmp_ifc_event(in_dev);
 #endif
 }
@@ -1322,7 +1319,7 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
 	spin_lock_init(&im->lock);
 #ifdef CONFIG_IP_MULTICAST
 	setup_timer(&im->timer, igmp_timer_expire, (unsigned long)im);
-	im->unsolicit_count = IGMP_Unsolicited_Report_Count;
+	im->unsolicit_count = sysctl_igmp_qrv;
 #endif
 
 	im->next_rcu = in_dev->mc_list;
@@ -1460,7 +1457,7 @@ void ip_mc_init_dev(struct in_device *in_dev)
 			(unsigned long)in_dev);
 	setup_timer(&in_dev->mr_ifc_timer, igmp_ifc_timer_expire,
 			(unsigned long)in_dev);
-	in_dev->mr_qrv = IGMP_Unsolicited_Report_Count;
+	in_dev->mr_qrv = sysctl_igmp_qrv;
 #endif
 
 	spin_lock_init(&in_dev->mc_tomb_lock);
@@ -1474,6 +1471,9 @@ void ip_mc_up(struct in_device *in_dev)
 
 	ASSERT_RTNL();
 
+#ifdef CONFIG_IP_MULTICAST
+	in_dev->mr_qrv = sysctl_igmp_qrv;
+#endif
 	ip_mc_inc_group(in_dev, IGMP_ALL_HOSTS);
 
 	for_each_pmc_rtnl(in_dev, pmc)
@@ -1540,7 +1540,9 @@ static struct in_device *ip_mc_find_dev(struct net *net, struct ip_mreqn *imr)
  */
 int sysctl_igmp_max_memberships __read_mostly = IP_MAX_MEMBERSHIPS;
 int sysctl_igmp_max_msf __read_mostly = IP_MAX_MSF;
-
+#ifdef CONFIG_IP_MULTICAST
+int sysctl_igmp_qrv __read_mostly = IGMP_Query_Robustness_Variable;
+#endif
 
 static int ip_mc_del1_src(struct ip_mc_list *pmc, int sfmode,
 	__be32 *psfsrc)
@@ -1575,8 +1577,7 @@ static int ip_mc_del1_src(struct ip_mc_list *pmc, int sfmode,
 #ifdef CONFIG_IP_MULTICAST
 		if (psf->sf_oldin &&
 		    !IGMP_V1_SEEN(in_dev) && !IGMP_V2_SEEN(in_dev)) {
-			psf->sf_crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-				IGMP_Unsolicited_Report_Count;
+			psf->sf_crcount = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 			psf->sf_next = pmc->tomb;
 			pmc->tomb = psf;
 			rv = 1;
@@ -1639,8 +1640,7 @@ static int ip_mc_del_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
 		/* filter mode change */
 		pmc->sfmode = MCAST_INCLUDE;
 #ifdef CONFIG_IP_MULTICAST
-		pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-			IGMP_Unsolicited_Report_Count;
+		pmc->crcount = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 		in_dev->mr_ifc_count = pmc->crcount;
 		for (psf = pmc->sources; psf; psf = psf->sf_next)
 			psf->sf_crcount = 0;
@@ -1818,8 +1818,7 @@ static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
 #ifdef CONFIG_IP_MULTICAST
 		/* else no filters; keep old mode for reports */
 
-		pmc->crcount = in_dev->mr_qrv ? in_dev->mr_qrv :
-			IGMP_Unsolicited_Report_Count;
+		pmc->crcount = in_dev->mr_qrv ?: sysctl_igmp_qrv;
 		in_dev->mr_ifc_count = pmc->crcount;
 		for (psf = pmc->sources; psf; psf = psf->sf_next)
 			psf->sf_crcount = 0;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 79a007c..45d156d 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -450,6 +450,16 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
+#ifdef CONFIG_IP_MULTICAST
+	{
+		.procname	= "igmp_qrv",
+		.data		= &sysctl_igmp_qrv,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &one
+	},
+#endif
 	{
 		.procname	= "inet_peer_threshold",
 		.data		= &inet_peer_threshold,
-- 
1.9.3

Re: [PATCH net-next v3 1/2] ipv6: add sysctl_mld_qrv to configure query robustness variable

[Flavio Leitner]

On Tue, Sep 02, 2014 at 03:49:25PM +0200, Hannes Frederic Sowa wrote:
> This patch adds a new sysctl_mld_qrv knob to configure the mldv1/v2 query
> robustness variable. It specifies how many retransmit of unsolicited mld
> retransmit should happen. Admins might want to tune this on lossy links.
> 
> Also reset mld state on interface down/up, so we pick up new sysctl
> settings during interface up event.
> 
> IPv6 certification requests this knob to be available.
> 
> I didn't make this knob netns specific, as it is mostly a setting in a
> physical environment and should be per host.
> 
> Cc: Flavio Leitner <fbl@redhat.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---

Thanks very much Hannes!

Acked-by: Flavio Leitner <fbl@redhat.com>

Re: [PATCH net-next v3 2/2] ipv4: implement igmp_qrv sysctl to tune igmp robustness variable

[Flavio Leitner]

On Tue, Sep 02, 2014 at 03:49:26PM +0200, Hannes Frederic Sowa wrote:
> As in IPv6 people might increase the igmp query robustness variable to
> make sure unsolicited state change reports aren't lost on the network. Add
> and document this new knob to igmp code.
> 
> RFCs allow tuning this parameter back to first IGMP RFC, so we also use
> this setting for all counters, including source specific multicast.
> 
> Also take over sysctl value when upping the interface and don't reuse
> the last one seen on the interface.
> 
> Cc: Flavio Leitner <fbl@redhat.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---

Thanks again,
Acked-by: Flavio Leitner <fbl@redhat.com>

Re: [PATCH net-next v3 1/2] ipv6: add sysctl_mld_qrv to configure query robustness variable

[David Miller]

From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Tue,  2 Sep 2014 15:49:25 +0200

> This patch adds a new sysctl_mld_qrv knob to configure the mldv1/v2 query
> robustness variable. It specifies how many retransmit of unsolicited mld
> retransmit should happen. Admins might want to tune this on lossy links.
> 
> Also reset mld state on interface down/up, so we pick up new sysctl
> settings during interface up event.
> 
> IPv6 certification requests this knob to be available.
> 
> I didn't make this knob netns specific, as it is mostly a setting in a
> physical environment and should be per host.
> 
> Cc: Flavio Leitner <fbl@redhat.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Applied.

Re: [PATCH net-next v3 2/2] ipv4: implement igmp_qrv sysctl to tune igmp robustness variable

[David Miller]

From: Hannes Frederic Sowa <hannes@stressinduktion.org>
Date: Tue,  2 Sep 2014 15:49:26 +0200

> As in IPv6 people might increase the igmp query robustness variable to
> make sure unsolicited state change reports aren't lost on the network. Add
> and document this new knob to igmp code.
> 
> RFCs allow tuning this parameter back to first IGMP RFC, so we also use
> this setting for all counters, including source specific multicast.
> 
> Also take over sysctl value when upping the interface and don't reuse
> the last one seen on the interface.
> 
> Cc: Flavio Leitner <fbl@redhat.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Applied.