From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH] bridge: multicast: add sanity check for query source addresses Date: Tue, 4 Mar 2014 10:06:14 +0100 Message-ID: <20140304090614.GA3952@order.stressinduktion.org> References: <1393901855-18231-1-git-send-email-linus.luessing@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, bridge@lists.linux-foundation.org, Stephen Hemminger , "David S. Miller" , linux-kernel@vger.kernel.org, Jan Stancek , Florian Westphal To: Linus =?utf-8?Q?L=C3=BCssing?= Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:38604 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756582AbaCDJGQ (ORCPT ); Tue, 4 Mar 2014 04:06:16 -0500 Content-Disposition: inline In-Reply-To: <1393901855-18231-1-git-send-email-linus.luessing@web.de> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Mar 04, 2014 at 03:57:35AM +0100, Linus L=C3=BCssing wrote: > MLD queries are supposed to have an IPv6 link-local source address > according to RFC2710, section 4 and RFC3810, section 5.1.14. This pat= ch > adds a sanity check to ignore such broken MLD queries. >=20 > Without this check, such malformed MLD queries can result in a > denial of service: The queries are ignored by any MLD listener > therefore they will not respond with an MLD report. However, > without this patch these malformed MLD queries would enable the > snooping part in the bridge code, potentially shutting down the > according ports towards these hosts for multicast traffic as the > bridge did not learn about these listeners. >=20 > Reported-by: Jan Stancek > Signed-off-by: Linus L=C3=BCssing > --- > net/bridge/br_multicast.c | 6 ++++++ > 1 file changed, 6 insertions(+) >=20 > diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c > index ef66365..fb0e36f 100644 > --- a/net/bridge/br_multicast.c > +++ b/net/bridge/br_multicast.c > @@ -1235,6 +1235,12 @@ static int br_ip6_multicast_query(struct net_b= ridge *br, > (port && port->state =3D=3D BR_STATE_DISABLED)) > goto out; > =20 > + /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresse= s */ > + if (!(ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL)) { > + err =3D -EINVAL; > + goto out; > + } > + Shouldn't we allow empty source address, here? Routers are supposed to drop them but bridges care. Linux uses :: as source address as long as no valid LL addresses are available, e.g. at boot-up (RFC3810 5.2.13.). Greetings, Hannes