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// SPDX-License-Identifier: GPL-2.0
/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <bpf/bpf_helpers.h>
int _version SEC("version") = 1;
SEC("xdp.frags")
int xdp_adjust_frags(struct xdp_md *xdp)
{
__u8 *data_end = (void *)(long)xdp->data_end;
__u8 *data = (void *)(long)xdp->data;
__u8 val[16] = {};
__u32 offset;
int err;
if (data + sizeof(__u32) > data_end)
return XDP_DROP;
offset = *(__u32 *)data;
err = bpf_xdp_load_bytes(xdp, offset, val, sizeof(val));
if (err < 0)
return XDP_DROP;
if (val[0] != 0xaa || val[15] != 0xaa) /* marker */
return XDP_DROP;
val[0] = 0xbb; /* update the marker */
val[15] = 0xbb;
err = bpf_xdp_store_bytes(xdp, offset, val, sizeof(val));
if (err < 0)
return XDP_DROP;
return XDP_PASS;
}
char _license[] SEC("license") = "GPL";
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