[PATCH 4.19 011/170] net: clear skb->tstamp in forwarding paths

From: Greg Kroah-Hartman
Date: Mon Jan 07 2019 - 08:21:06 EST

4.19-stable review patch. If anyone has any objections, please let me know.


From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 8203e2d844d34af247a151d8ebd68553a6e91785 ]

Sergey reported that forwarding was no longer working
if fq packet scheduler was used.

This is caused by the recent switch to EDT model, since incoming
packets might have been timestamped by __net_timestamp()

__net_timestamp() uses ktime_get_real(), while fq expects packets

The fix is to clear skb->tstamp in forwarding paths.

Fixes: 80b14dee2bea ("net: Add a new socket option for a future transmit time.")
Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: Sergey Matyukevich <geomatsi@xxxxxxxxx>
Tested-by: Sergey Matyukevich <geomatsi@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
net/ipv4/ip_forward.c | 1 +
net/ipv6/ip6_output.c | 1 +
2 files changed, 2 insertions(+)

--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -72,6 +72,7 @@ static int ip_forward_finish(struct net
if (unlikely(opt->optlen))

+ skb->tstamp = 0;
return dst_output(net, sk, skb);

--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -378,6 +378,7 @@ static inline int ip6_forward_finish(str
__IP6_ADD_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len);

+ skb->tstamp = 0;
return dst_output(net, sk, skb);