Commit bd11f074 authored by Maciej Żenczykowski's avatar Maciej Żenczykowski Committed by David S. Miller
Browse files

ipv6 addrconf: implement RFC7559 router solicitation backoff 

This implements:
  https://tools.ietf.org/html/rfc7559

Backoff is performed according to RFC3315 section 14:
  https://tools.ietf.org/html/rfc3315#section-14



We allow setting /proc/sys/net/ipv6/conf/*/router_solicitations
to a negative value meaning an unlimited number of retransmits,
and we make this the new default (inline with the RFC).

We also add a new setting:
  /proc/sys/net/ipv6/conf/*/router_solicitation_max_interval
defaulting to 1 hour (per RFC recommendation).

Signed-off-by: default avatarMaciej Żenczykowski <maze@google.com>
Acked-by: default avatarErik Kline <ek@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bcdc6efa

include/linux/ipv6.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ struct ipv6_devconf { 
	__s32		dad_transmits;

	__s32		rtr_solicits;

	__s32		rtr_solicit_interval;

	__s32		rtr_solicit_max_interval;

	__s32		rtr_solicit_delay;

	__s32		force_mld_version;

	__s32		mldv1_unsolicited_report_interval;

include/net/addrconf.h

+2 −1
Original line number Diff line number Diff line 
#ifndef _ADDRCONF_H

#define _ADDRCONF_H



#define MAX_RTR_SOLICITATIONS		3

#define MAX_RTR_SOLICITATIONS		-1		/* unlimited */

#define RTR_SOLICITATION_INTERVAL	(4*HZ)

#define RTR_SOLICITATION_MAX_INTERVAL	(3600*HZ)	/* 1 hour */



#define MIN_VALID_LIFETIME		(2*3600)	/* 2 hours */

include/net/if_inet6.h

+1 −0
Original line number Diff line number Diff line
@@ -201,6 +201,7 @@ struct inet6_dev { 
	struct ipv6_devstat	stats;



	struct timer_list	rs_timer;

	__s32			rs_interval;	/* in jiffies */

	__u8			rs_probes;



	__u8			addr_gen_mode;

include/uapi/linux/ipv6.h

+1 −0
Original line number Diff line number Diff line
@@ -177,6 +177,7 @@ enum { 
	DEVCONF_DROP_UNICAST_IN_L2_MULTICAST,

	DEVCONF_DROP_UNSOLICITED_NA,

	DEVCONF_KEEP_ADDR_ON_DOWN,

	DEVCONF_RTR_SOLICIT_MAX_INTERVAL,

	DEVCONF_MAX

};

net/ipv6/addrconf.c

+44 −7
Original line number Diff line number Diff line
@@ -112,6 +112,27 @@ static inline u32 cstamp_delta(unsigned long cstamp) 
	return (cstamp - INITIAL_JIFFIES) * 100UL / HZ;

}



static inline s32 rfc3315_s14_backoff_init(s32 irt)

{

	/* multiply 'initial retransmission time' by 0.9 .. 1.1 */

	u64 tmp = (900000 + prandom_u32() % 200001) * (u64)irt;

	do_div(tmp, 1000000);

	return (s32)tmp;

}



static inline s32 rfc3315_s14_backoff_update(s32 rt, s32 mrt)

{

	/* multiply 'retransmission timeout' by 1.9 .. 2.1 */

	u64 tmp = (1900000 + prandom_u32() % 200001) * (u64)rt;

	do_div(tmp, 1000000);

	if ((s32)tmp > mrt) {

		/* multiply 'maximum retransmission time' by 0.9 .. 1.1 */

		tmp = (900000 + prandom_u32() % 200001) * (u64)mrt;

		do_div(tmp, 1000000);

	}

	return (s32)tmp;

}



#ifdef CONFIG_SYSCTL

static int addrconf_sysctl_register(struct inet6_dev *idev);

static void addrconf_sysctl_unregister(struct inet6_dev *idev);
@@ -187,6 +208,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { 
	.dad_transmits		= 1,

	.rtr_solicits		= MAX_RTR_SOLICITATIONS,

	.rtr_solicit_interval	= RTR_SOLICITATION_INTERVAL,

	.rtr_solicit_max_interval = RTR_SOLICITATION_MAX_INTERVAL,

	.rtr_solicit_delay	= MAX_RTR_SOLICITATION_DELAY,

	.use_tempaddr		= 0,

	.temp_valid_lft		= TEMP_VALID_LIFETIME,
@@ -232,6 +254,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { 
	.dad_transmits		= 1,

	.rtr_solicits		= MAX_RTR_SOLICITATIONS,

	.rtr_solicit_interval	= RTR_SOLICITATION_INTERVAL,

	.rtr_solicit_max_interval = RTR_SOLICITATION_MAX_INTERVAL,

	.rtr_solicit_delay	= MAX_RTR_SOLICITATION_DELAY,

	.use_tempaddr		= 0,

	.temp_valid_lft		= TEMP_VALID_LIFETIME,
@@ -3687,7 +3710,7 @@ static void addrconf_rs_timer(unsigned long data) 
	if (idev->if_flags & IF_RA_RCVD)

		goto out;



	if (idev->rs_probes++ < idev->cnf.rtr_solicits) {

	if (idev->rs_probes++ < idev->cnf.rtr_solicits || idev->cnf.rtr_solicits < 0) {

		write_unlock(&idev->lock);

		if (!ipv6_get_lladdr(dev, &lladdr, IFA_F_TENTATIVE))

			ndisc_send_rs(dev, &lladdr,
@@ -3696,11 +3719,13 @@ static void addrconf_rs_timer(unsigned long data) 
			goto put;



		write_lock(&idev->lock);

		idev->rs_interval = rfc3315_s14_backoff_update(

			idev->rs_interval, idev->cnf.rtr_solicit_max_interval);

		/* The wait after the last probe can be shorter */

		addrconf_mod_rs_timer(idev, (idev->rs_probes ==

					     idev->cnf.rtr_solicits) ?

				      idev->cnf.rtr_solicit_delay :

				      idev->cnf.rtr_solicit_interval);

				      idev->rs_interval);

	} else {

		/*

		 * Note: we do not support deprecated "all on-link"
@@ -3949,7 +3974,7 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp) 
	send_mld = ifp->scope == IFA_LINK && ipv6_lonely_lladdr(ifp);

	send_rs = send_mld &&

		  ipv6_accept_ra(ifp->idev) &&

		  ifp->idev->cnf.rtr_solicits > 0 &&

		  ifp->idev->cnf.rtr_solicits != 0 &&

		  (dev->flags&IFF_LOOPBACK) == 0;

	read_unlock_bh(&ifp->idev->lock);
@@ -3971,10 +3996,11 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp) 


		write_lock_bh(&ifp->idev->lock);

		spin_lock(&ifp->lock);

		ifp->idev->rs_interval = rfc3315_s14_backoff_init(

			ifp->idev->cnf.rtr_solicit_interval);

		ifp->idev->rs_probes = 1;

		ifp->idev->if_flags |= IF_RS_SENT;

		addrconf_mod_rs_timer(ifp->idev,

				      ifp->idev->cnf.rtr_solicit_interval);

		addrconf_mod_rs_timer(ifp->idev, ifp->idev->rs_interval);

		spin_unlock(&ifp->lock);

		write_unlock_bh(&ifp->idev->lock);

	}
@@ -4891,6 +4917,8 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, 
	array[DEVCONF_RTR_SOLICITS] = cnf->rtr_solicits;

	array[DEVCONF_RTR_SOLICIT_INTERVAL] =

		jiffies_to_msecs(cnf->rtr_solicit_interval);

	array[DEVCONF_RTR_SOLICIT_MAX_INTERVAL] =

		jiffies_to_msecs(cnf->rtr_solicit_max_interval);

	array[DEVCONF_RTR_SOLICIT_DELAY] =

		jiffies_to_msecs(cnf->rtr_solicit_delay);

	array[DEVCONF_FORCE_MLD_VERSION] = cnf->force_mld_version;
@@ -5099,7 +5127,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token) 
		return -EINVAL;

	if (!ipv6_accept_ra(idev))

		return -EINVAL;

	if (idev->cnf.rtr_solicits <= 0)

	if (idev->cnf.rtr_solicits == 0)

		return -EINVAL;



	write_lock_bh(&idev->lock);
@@ -5128,8 +5156,10 @@ update_lft: 


	if (update_rs) {

		idev->if_flags |= IF_RS_SENT;

		idev->rs_interval = rfc3315_s14_backoff_init(

			idev->cnf.rtr_solicit_interval);

		idev->rs_probes = 1;

		addrconf_mod_rs_timer(idev, idev->cnf.rtr_solicit_interval);

		addrconf_mod_rs_timer(idev, idev->rs_interval);

	}



	/* Well, that's kinda nasty ... */
@@ -5777,6 +5807,13 @@ static const struct ctl_table addrconf_sysctl[] = { 
		.mode		= 0644,

		.proc_handler	= proc_dointvec_jiffies,

	},

	{

		.procname	= "router_solicitation_max_interval",

		.data		= &ipv6_devconf.rtr_solicit_max_interval,

		.maxlen		= sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_dointvec_jiffies,

	},

	{

		.procname	= "router_solicitation_delay",

		.data		= &ipv6_devconf.rtr_solicit_delay,

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