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Message-ID: <20130521150616.GA8513@obelix.rh>
Date: Tue, 21 May 2013 12:06:16 -0300
From: Flavio Leitner <fbl@...hat.com>
To: Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc: netdev@...r.kernel.org,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
David Miller <davem@...emloft.net>
Subject: Re: possible bug in IPv6 MLD retransmissions
On Sat, May 18, 2013 at 07:31:05PM +0200, Hannes Frederic Sowa wrote:
> On Fri, May 17, 2013 at 12:24:49AM -0300, Flavio Leitner wrote:
> > A tcpdump captured while adding an IPv6 link-local address shows
> > two MLD reports. One with source ``::'' and another with the permanent
> > address.
> >
> > Well, if you increase dad_retransmits from 1 to 10, for instance,
> > then both MLD reports are sent with source address ``::'' which
> > according with specs should be ignored by the routers.
> >
> > [...]
> >
> > Therefore, I believe this is a bug in IPv6 MLD because it should
> > sent at least 2 MLD reports after DAD is completed.
> > The specs says:
> >
> > [..]
> >
> > Does that make any sense?
>
> Yes, this is unfortunate. RFC3590 clarifies this also for MLDv1 messages.
>
> Could you try following patch I just came up with?
It does work, but it would be better to send [Robustness Variable]
times, right?
thanks!
[PATCH] ipv6: resend MLD report if a link-local address completes DAD
RFC3590/RFC3810 specifies we should resend MLD reports as soon as a
valid link-local address is available. This patch always resends MLD
reports if a link-local address completes dad (even a valid one was
already available).
Reported-by: Flavio Leitner <fleitner@...hat.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: Flavio Leitner <fbl@...hat.com>
---
include/net/addrconf.h | 1 +
include/net/if_inet6.h | 2 ++
net/ipv6/addrconf.c | 9 ++++++++-
net/ipv6/mcast.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 58 insertions(+), 1 deletion(-)
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 84a6440..ddd331c 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -155,6 +155,7 @@ extern bool ipv6_chk_mcast_addr(struct net_device *dev,
const struct in6_addr *group,
const struct in6_addr *src_addr);
+extern void ipv6_mc_dad_complete(struct inet6_dev *idev);
/*
* identify MLD packets for MLD filter exceptions
*/
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
index 100fb8c..5c195b1 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -172,10 +172,12 @@ struct inet6_dev {
unsigned char mc_qrv;
unsigned char mc_gq_running;
unsigned char mc_ifc_count;
+ unsigned char mc_dad_count;
unsigned long mc_v1_seen;
unsigned long mc_maxdelay;
struct timer_list mc_gq_timer; /* general query timer */
struct timer_list mc_ifc_timer; /* interface change timer */
+ struct timer_list mc_dad_timer; /* dad complete mc timer */
struct ifacaddr6 *ac_list;
rwlock_t lock;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d1ab6ab..800222b 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3272,6 +3272,7 @@ out:
static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
{
struct net_device *dev = ifp->idev->dev;
+ int type = ipv6_addr_type(&ifp->addr);
/*
* Configure the address for reception. Now it is valid.
@@ -3279,6 +3280,12 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
ipv6_ifa_notify(RTM_NEWADDR, ifp);
+ /* While dad is in progress mld report's source address is in6_addrany.
+ * Resend with proper ll now.
+ */
+ if (type & IPV6_ADDR_LINKLOCAL)
+ ipv6_mc_dad_complete(ifp->idev);
+
/* If added prefix is link local and we are prepared to process
router advertisements, start sending router solicitations.
*/
@@ -3286,7 +3293,7 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
if (ipv6_accept_ra(ifp->idev) &&
ifp->idev->cnf.rtr_solicits > 0 &&
(dev->flags&IFF_LOOPBACK) == 0 &&
- (ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL)) {
+ (type & IPV6_ADDR_LINKLOCAL)) {
/*
* If a host as already performed a random delay
* [...] as part of DAD [...] there is no need
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index bfa6cc3..9941ff7 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -999,6 +999,14 @@ static void mld_ifc_start_timer(struct inet6_dev *idev, int delay)
in6_dev_hold(idev);
}
+static void mld_dad_start_timer(struct inet6_dev *idev, int delay)
+{
+ int tv = net_random() % delay;
+
+ if (!mod_timer(&idev->mc_dad_timer, jiffies+tv+2))
+ in6_dev_hold(idev);
+}
+
/*
* IGMP handling (alias multicast ICMPv6 messages)
*/
@@ -1814,6 +1822,41 @@ err_out:
goto out;
}
+void ipv6_mc_dad_complete(struct inet6_dev *idev)
+{
+ idev->mc_dad_count = idev->mc_qrv;
+ mld_dad_start_timer(idev, 1);
+}
+
+static void mld_resend_report(struct inet6_dev *idev)
+{
+ if (MLD_V1_SEEN(idev)) {
+ struct ifmcaddr6 *mcaddr;
+ read_lock_bh(&idev->lock);
+ for (mcaddr = idev->mc_list; mcaddr; mcaddr = mcaddr->next) {
+ if (!(mcaddr->mca_flags & MAF_NOREPORT))
+ igmp6_send(&mcaddr->mca_addr, idev->dev,
+ ICMPV6_MGM_REPORT);
+ }
+ read_unlock_bh(&idev->lock);
+ } else {
+ mld_send_report(idev, NULL);
+ }
+}
+
+static void mld_dad_timer_expire(unsigned long data)
+{
+ struct inet6_dev *idev = (struct inet6_dev *)data;
+
+ mld_resend_report(idev);
+ if (idev->mc_dad_count) {
+ idev->mc_dad_count--;
+ if (idev->mc_dad_count)
+ mld_dad_start_timer(idev, idev->mc_maxdelay);
+ }
+ __in6_dev_put(idev);
+}
+
static int ip6_mc_del1_src(struct ifmcaddr6 *pmc, int sfmode,
const struct in6_addr *psfsrc)
{
@@ -2231,6 +2274,8 @@ void ipv6_mc_down(struct inet6_dev *idev)
idev->mc_gq_running = 0;
if (del_timer(&idev->mc_gq_timer))
__in6_dev_put(idev);
+ if (del_timer(&idev->mc_dad_timer))
+ __in6_dev_put(idev);
for (i = idev->mc_list; i; i=i->next)
igmp6_group_dropped(i);
@@ -2267,6 +2312,8 @@ void ipv6_mc_init_dev(struct inet6_dev *idev)
idev->mc_ifc_count = 0;
setup_timer(&idev->mc_ifc_timer, mld_ifc_timer_expire,
(unsigned long)idev);
+ setup_timer(&idev->mc_dad_timer, mld_dad_timer_expire,
+ (unsigned long)idev);
idev->mc_qrv = MLD_QRV_DEFAULT;
idev->mc_maxdelay = IGMP6_UNSOLICITED_IVAL;
idev->mc_v1_seen = 0;
--
1.8.1.4
--
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