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net: ipv6: mld: implement RFC3810 MLDv2 mode only 

RFC3810, 10. Security Considerations says under subsection 10.1.
Query Message:

  A forged Version 1 Query message will put MLDv2 listeners on that
  link in MLDv1 Host Compatibility Mode. This scenario can be avoided
  by providing MLDv2 hosts with a configuration option to ignore
  Version 1 messages completely.

Hence, implement a MLDv2-only mode that will ignore MLDv1 traffic:

  echo 2 > /proc/sys/net/ipv6/conf/ethX/force_mld_version  or
  echo 2 > /proc/sys/net/ipv6/conf/all/force_mld_version

Note that <all> device has a higher precedence as it was previously
also the case in the macro MLD_V1_SEEN() that would "short-circuit"
if condition on <all> case.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2013-09-04 00:19:40 +02:00 committed by David S. Miller
parent e3f5b17047
commit 58c0ecfd8d
1 changed files with 30 additions and 4 deletions
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34
net/ipv6/mcast.c
View File

@ -1112,11 +1112,34 @@ static bool mld_marksources(struct ifmcaddr6 *pmc, int nsrcs,
return true;
}
static int mld_force_mld_version(const struct inet6_dev *idev)
{
/* Normally, both are 0 here. If enforcement to a particular is
* being used, individual device enforcement will have a lower
* precedence over 'all' device (.../conf/all/force_mld_version).
*/
if (dev_net(idev->dev)->ipv6.devconf_all->force_mld_version != 0)
return dev_net(idev->dev)->ipv6.devconf_all->force_mld_version;
else
return idev->cnf.force_mld_version;
}
static bool mld_in_v2_mode_only(const struct inet6_dev *idev)
{
return mld_force_mld_version(idev) == 2;
}
static bool mld_in_v1_mode_only(const struct inet6_dev *idev)
{
return mld_force_mld_version(idev) == 1;
}
static bool mld_in_v1_mode(const struct inet6_dev *idev)
{
if (dev_net(idev->dev)->ipv6.devconf_all->force_mld_version == 1)
return true;
if (idev->cnf.force_mld_version == 1)
if (mld_in_v2_mode_only(idev))
return false;
if (mld_in_v1_mode_only(idev))
return true;
if (idev->mc_v1_seen && time_before(jiffies, idev->mc_v1_seen))
return true;
@ -1223,7 +1246,6 @@ int igmp6_event_query(struct sk_buff *skb)
return -EINVAL;
idev = __in6_dev_get(skb->dev);
if (idev == NULL)
return 0;
@ -1236,6 +1258,10 @@ int igmp6_event_query(struct sk_buff *skb)
return -EINVAL;
if (len == MLD_V1_QUERY_LEN) {
/* Ignore v1 queries */
if (mld_in_v2_mode_only(idev))
return 0;
/* MLDv1 router present */
max_delay = msecs_to_jiffies(ntohs(mld->mld_maxdelay));