1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
|
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2024 ByteDance */
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
struct {
__uint(type, BPF_MAP_TYPE_SOCKMAP);
__uint(max_entries, 1);
__type(key, int);
__type(value, int);
} sock_map_rx SEC(".maps");
long change_tail_ret = 1;
SEC("sk_skb")
int prog_skb_verdict(struct __sk_buff *skb)
{
char *data, *data_end;
bpf_skb_pull_data(skb, 1);
data = (char *)(unsigned long)skb->data;
data_end = (char *)(unsigned long)skb->data_end;
if (data + 1 > data_end)
return SK_PASS;
if (data[0] == 'T') { /* Trim the packet */
change_tail_ret = bpf_skb_change_tail(skb, skb->len - 1, 0);
return SK_PASS;
} else if (data[0] == 'G') { /* Grow the packet */
change_tail_ret = bpf_skb_change_tail(skb, skb->len + 1, 0);
return SK_PASS;
} else if (data[0] == 'E') { /* Error */
change_tail_ret = bpf_skb_change_tail(skb, 65535, 0);
return SK_PASS;
}
return SK_PASS;
}
char _license[] SEC("license") = "GPL";
|
