1/* SPDX-License-Identifier: GPL-2.0
 2 * Copyright (c) 2018 Facebook
 3 *
 4 * This program is free software; you can redistribute it and/or
 5 * modify it under the terms of version 2 of the GNU General Public
 6 * License as published by the Free Software Foundation.
 7 */
 8#include <linux/bpf.h>
 9#include <linux/if_ether.h>
10#include "bpf_helpers.h"
11
12int _version SEC("version") = 1;
13
14SEC("xdp_adjust_tail")
15int _xdp_adjust_tail(struct xdp_md *xdp)
16{
17	void *data_end = (void *)(long)xdp->data_end;
18	void *data = (void *)(long)xdp->data;
19	int offset = 0;
20
21	if (data_end - data == 54)
22		offset = 256;
23	else
24		offset = 20;
25	if (bpf_xdp_adjust_tail(xdp, 0 - offset))
26		return XDP_DROP;
27	return XDP_TX;
28}
29
30char _license[] SEC("license") = "GPL";