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.

We now use the valid_ll_addr_cnt to check if it is necessary to resend
a new report.

Changes since Flavio Leitner's version:
a) adapt for valid_ll_addr_cnt
b) resend first reports directly in the path and just arm the timer for
   mc_qrv-1 resends.

Reported-by: Flavio Leitner <fleitner@redhat.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Flavio Leitner <fbl@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 67 insertions, 5 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 21f702704f24..f68eaf574d7e 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 1628b8f5fb26..736b5fb95474 100644
--- a/include/net/if_inet6.h
+++ b/include/net/if_inet6.h
@@ -174,10 +174,12 @@ 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 20d92ff2d690..12dd2fec045c 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3277,7 +3277,7 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
 {
         struct net_device *dev = ifp->idev->dev;
         struct in6_addr lladdr;
-        bool send_rs;
+        bool send_rs, send_mld;
 
         addrconf_del_dad_timer(ifp);
 
@@ -3293,14 +3293,21 @@ static void addrconf_dad_completed(struct inet6_ifaddr *ifp)
 
         read_lock_bh(&ifp->idev->lock);
         spin_lock(&ifp->lock);
-        send_rs = ipv6_accept_ra(ifp->idev) &&
+        send_mld = ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL &&
+                   ifp->idev->valid_ll_addr_cnt == 1;
+        send_rs = send_mld &&
+                  ipv6_accept_ra(ifp->idev) &&
                   ifp->idev->cnf.rtr_solicits > 0 &&
-                  (dev->flags&IFF_LOOPBACK) == 0 &&
-                  ipv6_addr_type(&ifp->addr) & IPV6_ADDR_LINKLOCAL &&
-                  ifp->idev->valid_ll_addr_cnt == 1;
+                  (dev->flags&IFF_LOOPBACK) == 0;
         spin_unlock(&ifp->lock);
         read_unlock_bh(&ifp->idev->lock);
 
+        /* While dad is in progress mld report's source address is in6_addrany.
+         * Resend with proper ll now.
+         */
+        if (send_mld)
+                ipv6_mc_dad_complete(ifp->idev);
+
         if (send_rs) {
                 /*
                  *      If a host as already performed a random delay
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 72c8bfe06bb4..502c877cbf10 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)
  */
@@ -1815,6 +1823,46 @@ err_out:
         goto out;
 }
 
+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);
+        }
+}
+
+void ipv6_mc_dad_complete(struct inet6_dev *idev)
+{
+        idev->mc_dad_count = idev->mc_qrv;
+        if (idev->mc_dad_count) {
+                mld_resend_report(idev);
+                idev->mc_dad_count--;
+                if (idev->mc_dad_count)
+                        mld_dad_start_timer(idev, idev->mc_maxdelay);
+        }
+}
+
+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)
 {
@@ -2232,6 +2280,8 @@ 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);
@@ -2268,6 +2318,8 @@ 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;