net: clear local_df when passing skb between namespaces

We must clear local_df when passing the skb between namespaces as the
packet is not local to the new namespace any more and thus may not get
fragmented by local rules. Fred Templin noticed that other namespaces
do fragment IPv6 packets while forwarding. Instead they should have send
back a PTB.

The same problem should be present when forwarding DF-IPv4 packets
between namespaces.

Reported-by: Templin, Fred L <Fred.L.Templin@boeing.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 2718fed53d8c..06e72d3cdf60 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3584,6 +3584,7 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet)
         skb->tstamp.tv64 = 0;
         skb->pkt_type = PACKET_HOST;
         skb->skb_iif = 0;
+        skb->local_df = 0;
         skb_dst_drop(skb);
         skb->mark = 0;
         secpath_reset(skb);