Commit 454594f3 authored by Linus Lüssing's avatar Linus Lüssing Committed by David S. Miller
Browse files

Revert "bridge: only expire the mdb entry when query is received" 



While this commit was a good attempt to fix issues occuring when no
multicast querier is present, this commit still has two more issues:

1) There are cases where mdb entries do not expire even if there is a
querier present. The bridge will unnecessarily continue flooding
multicast packets on the according ports.

2) Never removing an mdb entry could be exploited for a Denial of
Service by an attacker on the local link, slowly, but steadily eating up
all memory.

Actually, this commit became obsolete with
"bridge: disable snooping if there is no querier" (b00589af)
which included fixes for a few more cases.

Therefore reverting the following commits (the commit stated in the
commit message plus three of its follow up fixes):

====================
Revert "bridge: update mdb expiration timer upon reports."
This reverts commit f144febd.
Revert "bridge: do not call setup_timer() multiple times"
This reverts commit 1faabf2a.
Revert "bridge: fix some kernel warning in multicast timer"
This reverts commit c7e8e8a8.
Revert "bridge: only expire the mdb entry when query is received"
This reverts commit 9f00b2e7.
====================

CC: Cong Wang <amwang@redhat.com>
Signed-off-by: default avatarLinus Lüssing <linus.luessing@web.de>
Reviewed-by: default avatarVlad Yasevich <vyasevich@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 02cf4ebd

net/bridge/br_mdb.c

+1 −1
Original line number Diff line number Diff line
@@ -453,7 +453,7 @@ static int __br_mdb_del(struct net_bridge *br, struct br_mdb_entry *entry) 
		call_rcu_bh(&p->rcu, br_multicast_free_pg);

		err = 0;



		if (!mp->ports && !mp->mglist && mp->timer_armed &&

		if (!mp->ports && !mp->mglist &&

		    netif_running(br->dev))

			mod_timer(&mp->timer, jiffies);

		break;

net/bridge/br_multicast.c

+27 −20
Original line number Diff line number Diff line
@@ -272,7 +272,7 @@ static void br_multicast_del_pg(struct net_bridge *br, 
		del_timer(&p->timer);

		call_rcu_bh(&p->rcu, br_multicast_free_pg);



		if (!mp->ports && !mp->mglist && mp->timer_armed &&

		if (!mp->ports && !mp->mglist &&

		    netif_running(br->dev))

			mod_timer(&mp->timer, jiffies);
@@ -611,9 +611,6 @@ rehash: 
		break;



	default:

		/* If we have an existing entry, update it's expire timer */

		mod_timer(&mp->timer,

			  jiffies + br->multicast_membership_interval);

		goto out;

	}
@@ -623,7 +620,6 @@ rehash: 


	mp->br = br;

	mp->addr = *group;



	setup_timer(&mp->timer, br_multicast_group_expired,

		    (unsigned long)mp);
@@ -663,6 +659,7 @@ static int br_multicast_add_group(struct net_bridge *br, 
	struct net_bridge_mdb_entry *mp;

	struct net_bridge_port_group *p;

	struct net_bridge_port_group __rcu **pp;

	unsigned long now = jiffies;

	int err;



	spin_lock(&br->multicast_lock);
@@ -677,18 +674,15 @@ static int br_multicast_add_group(struct net_bridge *br, 


	if (!port) {

		mp->mglist = true;

		mod_timer(&mp->timer, now + br->multicast_membership_interval);

		goto out;

	}



	for (pp = &mp->ports;

	     (p = mlock_dereference(*pp, br)) != NULL;

	     pp = &p->next) {

		if (p->port == port) {

			/* We already have a portgroup, update the timer.  */

			mod_timer(&p->timer,

				  jiffies + br->multicast_membership_interval);

			goto out;

		}

		if (p->port == port)

			goto found;

		if ((unsigned long)p->port < (unsigned long)port)

			break;

	}
@@ -699,6 +693,8 @@ static int br_multicast_add_group(struct net_bridge *br, 
	rcu_assign_pointer(*pp, p);

	br_mdb_notify(br->dev, port, group, RTM_NEWMDB);



found:

	mod_timer(&p->timer, now + br->multicast_membership_interval);

out:

	err = 0;
@@ -1198,9 +1194,6 @@ static int br_ip4_multicast_query(struct net_bridge *br, 
	if (!mp)

		goto out;



	mod_timer(&mp->timer, now + br->multicast_membership_interval);

	mp->timer_armed = true;



	max_delay *= br->multicast_last_member_count;



	if (mp->mglist &&
@@ -1277,9 +1270,6 @@ static int br_ip6_multicast_query(struct net_bridge *br, 
	if (!mp)

		goto out;



	mod_timer(&mp->timer, now + br->multicast_membership_interval);

	mp->timer_armed = true;



	max_delay *= br->multicast_last_member_count;

	if (mp->mglist &&

	    (timer_pending(&mp->timer) ?
@@ -1365,7 +1355,7 @@ static void br_multicast_leave_group(struct net_bridge *br, 
			call_rcu_bh(&p->rcu, br_multicast_free_pg);

			br_mdb_notify(br->dev, port, group, RTM_DELMDB);



			if (!mp->ports && !mp->mglist && mp->timer_armed &&

			if (!mp->ports && !mp->mglist &&

			    netif_running(br->dev))

				mod_timer(&mp->timer, jiffies);

		}
@@ -1377,12 +1367,30 @@ static void br_multicast_leave_group(struct net_bridge *br, 
		     br->multicast_last_member_interval;



	if (!port) {

		if (mp->mglist && mp->timer_armed &&

		if (mp->mglist &&

		    (timer_pending(&mp->timer) ?

		     time_after(mp->timer.expires, time) :

		     try_to_del_timer_sync(&mp->timer) >= 0)) {

			mod_timer(&mp->timer, time);

		}



		goto out;

	}



	for (p = mlock_dereference(mp->ports, br);

	     p != NULL;

	     p = mlock_dereference(p->next, br)) {

		if (p->port != port)

			continue;



		if (!hlist_unhashed(&p->mglist) &&

		    (timer_pending(&p->timer) ?

		     time_after(p->timer.expires, time) :

		     try_to_del_timer_sync(&p->timer) >= 0)) {

			mod_timer(&p->timer, time);

		}



		break;

	}

out:

	spin_unlock(&br->multicast_lock);
@@ -1805,7 +1813,6 @@ void br_multicast_stop(struct net_bridge *br) 
		hlist_for_each_entry_safe(mp, n, &mdb->mhash[i],

					  hlist[ver]) {

			del_timer(&mp->timer);

			mp->timer_armed = false;

			call_rcu_bh(&mp->rcu, br_multicast_free_group);

		}

	}

net/bridge/br_private.h

+0 −1
Original line number Diff line number Diff line
@@ -126,7 +126,6 @@ struct net_bridge_mdb_entry 
	struct timer_list		timer;

	struct br_ip			addr;

	bool				mglist;

	bool				timer_armed;

};



struct net_bridge_mdb_htable

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