Return-path: Received: from mail-wi0-f181.google.com ([209.85.212.181]:37918 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752946Ab3LCJU0 (ORCPT ); Tue, 3 Dec 2013 04:20:26 -0500 Received: by mail-wi0-f181.google.com with SMTP id hq4so6160432wib.2 for ; Tue, 03 Dec 2013 01:20:25 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <1386010316-2540-1-git-send-email-johannes@sipsolutions.net> References: <1386010316-2540-1-git-send-email-johannes@sipsolutions.net> From: Krishna Chaitanya Date: Tue, 3 Dec 2013 14:50:05 +0530 Message-ID: (sfid-20131203_102035_600752_954AB66F) Subject: Re: [RFC] cfg80211/mac80211: drop GTK-protected unicast IP packets To: Johannes Berg Cc: linux-wireless , j@w1.fi, Johannes Berg Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Tue, Dec 3, 2013 at 12:21 AM, Johannes Berg wrote: > From: Johannes Berg > > The GTK is shared by all stations in an 802.11 BSS and as such any > one of them can send forged group-addressed frames. To prevent this > kind of attack, drop unicast IP packets if they were protected with > the GTK, i.e. were multicast packets at the 802.11 layer. > > Based in part on a patch by Jouni that did the same but in the IP > stack, which was considered too intrusive. > As per RFC 1122 this is an invalid case: When a host sends a datagram to a link-layer broadcast address, the IP destination address MUST be a legal IP broadcast or IP multicast address. A host SHOULD silently discard a datagram that is received via a link-layer broadcast (see Section 2.4) but does not specify an IP multicast or broadcast destination address. We can simply drop this frame irrespective of GTK/PTK is used.