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 12 int _version SEC("version") = 1; 13 14 SEC("xdp_adjust_tail") _xdp_adjust_tail(struct xdp_md * xdp)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 30 char _license[] SEC("license") = "GPL"; 31