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ipv6 addrconf: implement RFC7559 router solicitation backoff

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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: Maciej Żenczykowski <maze@google.com>
Acked-by: Erik Kline <ek@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Maciej Żenczykowski 2016-09-27 23:57:58 -07:00 committed by David S. Miller
parent bcdc6efabd
commit bd11f0741f
5 changed files with 49 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/ipv6.h
View File

@ -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;

3
include/net/addrconf.h
View File

@ -1,8 +1,9 @@
#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 */

1
include/net/if_inet6.h
View File

@ -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;

1
include/uapi/linux/ipv6.h
View File

@ -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
};

51
net/ipv6/addrconf.c
View File

@ -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 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
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,