| From | Ben Hutchings <> | Date | Tue, 05 May 2015 02:16:39 +0100 | Subject | [PATCH 3.2 187/221] ipv6: stop sending PTB packets for MTU < 1280 |
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3.2.69-rc1 review patch. If anyone has any objections, please let me know.
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From: Hagen Paul Pfeifer <hagen@jauu.net>
[ 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 <fgont@si6networks.com> Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/ipv6/route.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
--- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1018,12 +1018,9 @@ static void ip6_rt_update_pmtu(struct ds if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) { 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); } }
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