From 92dd5452c1be873a1193561f4f691763103d22ac Mon Sep 17 00:00:00 2001 From: Edward Cree Date: Tue, 19 Sep 2017 18:45:56 +0100 Subject: [PATCH] net: change skb->mac_header when Generic XDP calls adjust_head 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 Signed-off-by: David S. Miller --- net/core/dev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/core/dev.c b/net/core/dev.c index fb766d906148..9a2254f9802f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3892,6 +3892,7 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, __skb_pull(skb, off); else if (off < 0) __skb_push(skb, -off); + skb->mac_header += off; switch (act) { case XDP_REDIRECT: -- 2.20.1