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ipv6: add option to drop unicast encapsulated in L2 multicast

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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>
This commit is contained in:
Johannes Berg
2016-02-04 13:31:19 +01:00
committed by David S. Miller
parent 97daf33145
commit abbc30436d
5 changed files with 26 additions and 0 deletions
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8
net/ipv6/addrconf.c
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@@ -4711,6 +4711,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
array[DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN] = cnf->ignore_routes_with_linkdown;
/* we omit DEVCONF_STABLE_SECRET for now */
array[DEVCONF_USE_OIF_ADDRS_ONLY] = cnf->use_oif_addrs_only;
array[DEVCONF_DROP_UNICAST_IN_L2_MULTICAST] = cnf->drop_unicast_in_l2_multicast;
}
static inline size_t inet6_ifla6_size(void)
@@ -5784,6 +5785,13 @@ static struct addrconf_sysctl_table
.mode = 0644,
.proc_handler = addrconf_sysctl_ignore_routes_with_linkdown,
},
{
.procname = "drop_unicast_in_l2_multicast",
.data = &ipv6_devconf.drop_unicast_in_l2_multicast,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec,
},
{
/* sentinel */
}