Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2024 ByteDance */
3#include "vmlinux.h"
4#include <bpf/bpf_helpers.h>
5
6#ifndef PAGE_SIZE
7#define PAGE_SIZE __PAGE_SIZE
8#endif
9#define BPF_SKB_MAX_LEN (PAGE_SIZE << 2)
10
11struct {
12 __uint(type, BPF_MAP_TYPE_SOCKMAP);
13 __uint(max_entries, 1);
14 __type(key, int);
15 __type(value, int);
16} sock_map_rx SEC(".maps");
17
18long change_tail_ret = 1;
19
20SEC("sk_skb")
21int prog_skb_verdict(struct __sk_buff *skb)
22{
23 char *data, *data_end;
24
25 bpf_skb_pull_data(skb, 1);
26 data = (char *)(unsigned long)skb->data;
27 data_end = (char *)(unsigned long)skb->data_end;
28
29 if (data + 1 > data_end)
30 return SK_PASS;
31
32 if (data[0] == 'T') { /* Trim the packet */
33 change_tail_ret = bpf_skb_change_tail(skb, skb->len - 1, 0);
34 return SK_PASS;
35 } else if (data[0] == 'G') { /* Grow the packet */
36 change_tail_ret = bpf_skb_change_tail(skb, skb->len + 1, 0);
37 return SK_PASS;
38 } else if (data[0] == 'E') { /* Error */
39 change_tail_ret = bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0);
40 return SK_PASS;
41 }
42 return SK_PASS;
43}
44
45char _license[] SEC("license") = "GPL";