4.13-stable review patch. If anyone has any objections, please let me know.
------------------
From: Edward Cree <ecree@xxxxxxxxxxxxxx>
[ Upstream commit 92dd5452c1be873a1193561f4f691763103d22ac ]
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@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/core/dev.c | 1 +
1 file changed, 1 insertion(+)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4408,6 +4408,7 @@ 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_TX: