From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756059AbaCDC5s (ORCPT ); Mon, 3 Mar 2014 21:57:48 -0500 Received: from mout.web.de ([212.227.15.3]:54881 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755929AbaCDC5q (ORCPT ); Mon, 3 Mar 2014 21:57:46 -0500 From: =?UTF-8?q?Linus=20L=C3=BCssing?= To: netdev@vger.kernel.org Cc: bridge@lists.linux-foundation.org, Stephen Hemminger , "David S. Miller" , linux-kernel@vger.kernel.org, Jan Stancek , Florian Westphal , =?UTF-8?q?Linus=20L=C3=BCssing?= Subject: [PATCH] bridge: multicast: add sanity check for query source addresses Date: Tue, 4 Mar 2014 03:57:35 +0100 Message-Id: <1393901855-18231-1-git-send-email-linus.luessing@web.de> X-Mailer: git-send-email 1.9.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K0:+iLylx3khIMy5UaaYok5M3rpxiCUNfSnfthvKabSV7h0zLfOKLZ aD6Zc/h1N9iUKlBdWEsi66lXYC48GITy6ZpgU5ughSkcBFmucg6cHfQE/frI7Iots9sqtvG nSM5F00U96lavRfHUatYhMav8CScejXbxu/mHOqUkeQatsVAW6qv11BVHlKO1SvKoSPDyED 2CnSGMEe1i5nqgaN25uiw== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org MLD queries are supposed to have an IPv6 link-local source address according to RFC2710, section 4 and RFC3810, section 5.1.14. This patch adds a sanity check to ignore such broken MLD queries. 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. Reported-by: Jan Stancek Signed-off-by: Linus Lüssing --- net/bridge/br_multicast.c | 6 ++++++ 1 file changed, 6 insertions(+) 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_bridge *br, (port && port->state == BR_STATE_DISABLED)) goto out; + /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */ + if (!(ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL)) { + err = -EINVAL; + goto out; + } + if (skb->len == sizeof(*mld)) { if (!pskb_may_pull(skb, sizeof(*mld))) { err = -EINVAL; -- 1.7.10.4