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

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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" (b00589af3b)
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 f144febd93.
Revert "bridge: do not call setup_timer() multiple times"
This reverts commit 1faabf2aab.
Revert "bridge: fix some kernel warning in multicast timer"
This reverts commit c7e8e8a8f7.
Revert "bridge: only expire the mdb entry when query is received"
This reverts commit 9f00b2e7cf.
====================

CC: Cong Wang <amwang@redhat.com>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Reviewed-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Linus Lüssing 2013-10-20 00:58:57 +02:00 committed by David S. Miller
parent 02cf4ebd82
commit 454594f3b9
3 changed files with 28 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
net/bridge/br_mdb.c
View File

@ -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;

47
net/bridge/br_multicast.c
View File

@ -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);
}
}

1
net/bridge/br_private.h
View File

@ -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