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ipv4: add option to drop gratuitous ARP packets

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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 <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Johannes Berg
2016-02-04 13:31:18 +01:00
committed by David S. Miller
parent 12b74dfadb
commit 97daf33145
4 changed files with 17 additions and 0 deletions
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8
net/ipv4/arp.c
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@@ -735,6 +735,14 @@ static int arp_process(struct net *net, struct sock *sk, 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 (sip == tip && IN_DEV_ORCONF(in_dev, DROP_GRATUITOUS_ARP))
goto out;
/*
* Special case: We must set Frame Relay source Q.922 address
*/