Hello,
On Fri, 10 Apr 2015, Johannes Berg wrote:
> From: Johannes Berg <[email protected]>
>
> In certain 802.11 wireless deployments, there will be ARP proxies
> that use knowledge of the network to correctly answer requests.
> To prevent gratuitous ARP frames on the shared medium from being
> a problem, on such deployments wireless needs to drop them.
>
> Enable this by providing an option called "drop_gratuitous_arp".
>
> Signed-off-by: Johannes Berg <[email protected]>
> diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> index 5f5c674e130a..5487d5e5191e 100644
> --- a/net/ipv4/arp.c
> +++ b/net/ipv4/arp.c
> @@ -715,6 +715,14 @@ static int arp_process(struct sk_buff *skb)
> (!IN_DEV_ROUTE_LOCALNET(in_dev) && ipv4_is_loopback(tip)))
> goto out;
>
> + /*
> + * For some 802.11 wireless deployments (and possibly other networks),
> + * there will be an ARP proxy and gratuitous ARP frames are attacks
> + * and thus should not be accepted.
> + */
> + if (IN_DEV_CONF_GET(in_dev, DROP_GRATUITOUS_ARP) && sip == tip)
> + goto out;
Does it happen for any pkt_type? IN_DEV_ARP_ACCEPT
is not ON by default, so new entries are not created but
update can happen at any time, even with simple request like
who-has OURIP tell PROXYIP and sha=hacker_mac sent by
attackers. Is that the only gap that needs to be protected
with this patch?
May be only arptable_filter can help here to
protect ARP?
Regards
--
Julian Anastasov <[email protected]>
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
