From 58c0ecfd8d9871cfa35bcdbf3e7b3ee9ca62ea67 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Wed, 4 Sep 2013 00:19:40 +0200 Subject: [PATCH] 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 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 case. Signed-off-by: Daniel Borkmann Cc: Hannes Frederic Sowa Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv6/mcast.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 005b22fd6bcb..c916568d838a 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -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)); -- 2.30.2