Commit 92dd5452 authored Sep 19, 2017 by Edward Cree Committed by David S. Miller Sep 20, 2017

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: b5cdae32 ("net: Generic XDP")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent c2a64bb9

net/core/dev.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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:

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