diff options
| author | Johannes Berg <johannes.berg@intel.com> | 2016-02-04 13:31:19 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-02-11 04:27:36 -0500 |
| commit | abbc30436d39dfed8ebfca338d253f211ac7b094 (patch) | |
| tree | d7ce58e0300818d2effa7a7bd03bd5667f0d9d36 /net/ipv6 | |
| parent | 97daf331455077645ae1f13438bebd3d1a2e94ee (diff) | |
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>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/addrconf.c | 8 | ||||
| -rw-r--r-- | net/ipv6/ip6_input.c | 10 |
2 files changed, 18 insertions, 0 deletions
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 38eeddedfc21..23e325f39f8e 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -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) @@ -5785,6 +5786,13 @@ static struct addrconf_sysctl_table .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 */ } }, diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c index 9075acf081dd..31ac3c56da4b 100644 --- a/net/ipv6/ip6_input.c +++ b/net/ipv6/ip6_input.c @@ -134,6 +134,16 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1) goto err; + /* If enabled, drop unicast packets that were encapsulated in link-layer + * multicast or broadcast to protected against the so-called "hole-196" + * attack in 802.11 wireless. + */ + if (!ipv6_addr_is_multicast(&hdr->daddr) && + (skb->pkt_type == PACKET_BROADCAST || + skb->pkt_type == PACKET_MULTICAST) && + idev->cnf.drop_unicast_in_l2_multicast) + goto err; + /* RFC4291 2.7 * Nodes must not originate a packet to a multicast address whose scope * field contains the reserved value 0; if such a packet is received, it |