From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Fernando Gont , Hagen Paul Pfeifer , Hannes Frederic Sowa , "David S. Miller" Subject: [PATCH 3.10 03/16] ipv6: stop sending PTB packets for MTU < 1280 Date: Tue, 24 Feb 2015 18:09:55 -0800 Message-Id: <20150225020811.594308663@linuxfoundation.org> In-Reply-To: <20150225020811.453644010@linuxfoundation.org> References: <20150225020811.453644010@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hagen Paul Pfeifer [ Upstream commit 9d289715eb5c252ae15bd547cb252ca547a3c4f2 ] Reduce the attack vector and stop generating IPv6 Fragment Header for paths with an MTU smaller than the minimum required IPv6 MTU size (1280 byte) - called atomic fragments. See IETF I-D "Deprecating the Generation of IPv6 Atomic Fragments" [1] for more information and how this "feature" can be misused. [1] https://tools.ietf.org/html/draft-ietf-6man-deprecate-atomfrag-generation-00 Signed-off-by: Fernando Gont Signed-off-by: Hagen Paul Pfeifer Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/route.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1141,12 +1141,9 @@ static void ip6_rt_update_pmtu(struct ds struct net *net = dev_net(dst->dev); rt6->rt6i_flags |= RTF_MODIFIED; - if (mtu < IPV6_MIN_MTU) { - u32 features = dst_metric(dst, RTAX_FEATURES); + if (mtu < IPV6_MIN_MTU) mtu = IPV6_MIN_MTU; - features |= RTAX_FEATURE_ALLFRAG; - dst_metric_set(dst, RTAX_FEATURES, features); - } + dst_metric_set(dst, RTAX_MTU, mtu); rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires); }