1// SPDX-License-Identifier: GPL-2.0
2#include <linux/bpf.h>
3#include <bpf/bpf_endian.h>
4#include <bpf/bpf_helpers.h>
5#include <linux/ip.h>
6#include "bpf_tracing_net.h"
7
8/* We don't care about whether the packet can be received by network stack.
9 * Just care if the packet is sent to the correct device at correct direction
10 * and not panic the kernel.
11 */
12static int prepend_dummy_mac(struct __sk_buff *skb)
13{
14	char mac[] = {0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0xf,
15		      0xe, 0xd, 0xc, 0xb, 0xa, 0x08, 0x00};
16
17	if (bpf_skb_change_head(skb, ETH_HLEN, 0))
18		return -1;
19
20	if (bpf_skb_store_bytes(skb, 0, mac, sizeof(mac), 0))
21		return -1;
22
23	return 0;
24}
25
26/* Use the last byte of IP address to redirect the packet */
27static int get_redirect_target(struct __sk_buff *skb)
28{
29	struct iphdr *iph = NULL;
30	void *start = (void *)(long)skb->data;
31	void *end = (void *)(long)skb->data_end;
32
33	if (start + sizeof(*iph) > end)
34		return -1;
35
36	iph = (struct iphdr *)start;
37	return bpf_ntohl(iph->daddr) & 0xff;
38}
39
40SEC("redir_ingress")
41int test_lwt_redirect_in(struct __sk_buff *skb)
42{
43	int target = get_redirect_target(skb);
44
45	if (target < 0)
46		return BPF_OK;
47
48	if (prepend_dummy_mac(skb))
49		return BPF_DROP;
50
51	return bpf_redirect(target, BPF_F_INGRESS);
52}
53
54SEC("redir_egress")
55int test_lwt_redirect_out(struct __sk_buff *skb)
56{
57	int target = get_redirect_target(skb);
58
59	if (target < 0)
60		return BPF_OK;
61
62	if (prepend_dummy_mac(skb))
63		return BPF_DROP;
64
65	return bpf_redirect(target, 0);
66}
67
68SEC("redir_egress_nomac")
69int test_lwt_redirect_out_nomac(struct __sk_buff *skb)
70{
71	int target = get_redirect_target(skb);
72
73	if (target < 0)
74		return BPF_OK;
75
76	return bpf_redirect(target, 0);
77}
78
79SEC("redir_ingress_nomac")
80int test_lwt_redirect_in_nomac(struct __sk_buff *skb)
81{
82	int target = get_redirect_target(skb);
83
84	if (target < 0)
85		return BPF_OK;
86
87	return bpf_redirect(target, BPF_F_INGRESS);
88}
89
90char _license[] SEC("license") = "GPL";
91