ipv6: add option to drop unicast encapsulated in L2 multicast

In order to solve a problem with 802.11, the so-called hole-196 attack,
add an option (sysctl) called "drop_unicast_in_l2_multicast" which, if
enabled, causes the stack to drop IPv6 unicast packets encapsulated in
link-layer multi- or broadcast frames. Such frames can (as an attack)
be created by any member of the same wireless network and transmitted
as valid encrypted frames since the symmetric key for broadcast frames
is shared between all stations.

Reviewed-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 38b4fef20219..4c413570efe8 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -174,6 +174,7 @@ enum {
         DEVCONF_USE_OIF_ADDRS_ONLY,
         DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT,
         DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
+        DEVCONF_DROP_UNICAST_IN_L2_MULTICAST,
         DEVCONF_MAX
 };