Commit abbc3043 authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller

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: default avatarJulian Anastasov <ja@ssi.bg>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 97daf331
...@@ -1674,6 +1674,12 @@ stable_secret - IPv6 address ...@@ -1674,6 +1674,12 @@ stable_secret - IPv6 address
By default the stable secret is unset. By default the stable secret is unset.
drop_unicast_in_l2_multicast - BOOLEAN
Drop any unicast IPv6 packets that are received in link-layer
multicast (or broadcast) frames.
By default this is turned off.
icmp/*: icmp/*:
ratelimit - INTEGER ratelimit - INTEGER
Limit the maximal rates for sending ICMPv6 packets. Limit the maximal rates for sending ICMPv6 packets.
......
...@@ -50,6 +50,7 @@ struct ipv6_devconf { ...@@ -50,6 +50,7 @@ struct ipv6_devconf {
__s32 mc_forwarding; __s32 mc_forwarding;
#endif #endif
__s32 disable_ipv6; __s32 disable_ipv6;
__s32 drop_unicast_in_l2_multicast;
__s32 accept_dad; __s32 accept_dad;
__s32 force_tllao; __s32 force_tllao;
__s32 ndisc_notify; __s32 ndisc_notify;
......
...@@ -174,6 +174,7 @@ enum { ...@@ -174,6 +174,7 @@ enum {
DEVCONF_USE_OIF_ADDRS_ONLY, DEVCONF_USE_OIF_ADDRS_ONLY,
DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT, DEVCONF_ACCEPT_RA_MIN_HOP_LIMIT,
DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN, DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
DEVCONF_DROP_UNICAST_IN_L2_MULTICAST,
DEVCONF_MAX DEVCONF_MAX
}; };
......
...@@ -4711,6 +4711,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, ...@@ -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; array[DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN] = cnf->ignore_routes_with_linkdown;
/* we omit DEVCONF_STABLE_SECRET for now */ /* we omit DEVCONF_STABLE_SECRET for now */
array[DEVCONF_USE_OIF_ADDRS_ONLY] = cnf->use_oif_addrs_only; 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) static inline size_t inet6_ifla6_size(void)
...@@ -5784,6 +5785,13 @@ static struct addrconf_sysctl_table ...@@ -5784,6 +5785,13 @@ static struct addrconf_sysctl_table
.mode = 0644, .mode = 0644,
.proc_handler = addrconf_sysctl_ignore_routes_with_linkdown, .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 */ /* sentinel */
} }
......
...@@ -134,6 +134,16 @@ int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt ...@@ -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) IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
goto err; 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 /* RFC4291 2.7
* Nodes must not originate a packet to a multicast address whose scope * 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 * field contains the reserved value 0; if such a packet is received, it
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment