ipv6: stop sending PTB packets for MTU < 1280
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>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c910831..166e33b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1160,12 +1160,9 @@
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);
}