1#include <linux/bpf.h>
 2#include "bpf_helpers.h"
 3#include "bpf_util.h"
 4#include "bpf_endian.h"
 5
 6int _version SEC("version") = 1;
 7
 8#define bpf_printk(fmt, ...)					\
 9({								\
10	       char ____fmt[] = fmt;				\
11	       bpf_trace_printk(____fmt, sizeof(____fmt),	\
12				##__VA_ARGS__);			\
13})
14
15SEC("sk_skb1")
16int bpf_prog1(struct __sk_buff *skb)
17{
18	void *data_end = (void *)(long) skb->data_end;
19	void *data = (void *)(long) skb->data;
20	__u32 lport = skb->local_port;
21	__u32 rport = skb->remote_port;
22	__u8 *d = data;
23	__u32 len = (__u32) data_end - (__u32) data;
24	int err;
25
26	if (data + 10 > data_end) {
27		err = bpf_skb_pull_data(skb, 10);
28		if (err)
29			return SK_DROP;
30
31		data_end = (void *)(long)skb->data_end;
32		data = (void *)(long)skb->data;
33		if (data + 10 > data_end)
34			return SK_DROP;
35	}
36
37	/* This write/read is a bit pointless but tests the verifier and
38	 * strparser handler for read/write pkt data and access into sk
39	 * fields.
40	 */
41	d = data;
42	d[7] = 1;
43	return skb->len;
44}
45
46char _license[] SEC("license") = "GPL";