From: Edward Cree <ecree@solarflare.com>
Date: Tue, 19 Sep 2017 18:45:56 +0100
Subject: net: change skb->mac_header when Generic XDP calls adjust_head
Patch-mainline: v4.14-rc2
Git-commit: 92dd5452c1be873a1193561f4f691763103d22ac
References: bsc#1056787

Since XDP's view of the packet includes the MAC header, moving the start-
 of-packet with bpf_xdp_adjust_head needs to also update the offset of the
 MAC header (which is relative to skb->head, not to the skb->data that was
 changed).
Without this, tcpdump sees packets starting from the old MAC header rather
 than the new one, at least in my tests on the loopback device.

Fixes: b5cdae3291f7 ("net: Generic XDP")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/core/dev.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3900,6 +3900,7 @@ static u32 netif_receive_generic_xdp(str
 		__skb_pull(skb, off);
 	else if (off < 0)
 		__skb_push(skb, -off);
+	skb->mac_header += off;
 
 	switch (act) {
 	case XDP_REDIRECT: