1// SPDX-License-Identifier: GPL-2.0
2#include <stdint.h>
3#include <stdbool.h>
4
5#include <linux/bpf.h>
6#include <linux/stddef.h>
7#include <linux/pkt_cls.h>
8#include <linux/if_ether.h>
9#include <linux/ip.h>
10
11#include <bpf/bpf_helpers.h>
12
13volatile const __u32 IFINDEX_SRC;
14volatile const __u32 IFINDEX_DST;
15
16static const __u8 src_mac[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55};
17static const __u8 dst_mac[] = {0x00, 0x22, 0x33, 0x44, 0x55, 0x66};
18
19SEC("tc")
20int tc_chk(struct __sk_buff *skb)
21{
22	return TC_ACT_SHOT;
23}
24
25SEC("tc")
26int tc_dst(struct __sk_buff *skb)
27{
28	return bpf_redirect_peer(IFINDEX_SRC, 0);
29}
30
31SEC("tc")
32int tc_src(struct __sk_buff *skb)
33{
34	return bpf_redirect_peer(IFINDEX_DST, 0);
35}
36
37SEC("tc")
38int tc_dst_l3(struct __sk_buff *skb)
39{
40	return bpf_redirect(IFINDEX_SRC, 0);
41}
42
43SEC("tc")
44int tc_src_l3(struct __sk_buff *skb)
45{
46	__u16 proto = skb->protocol;
47
48	if (bpf_skb_change_head(skb, ETH_HLEN, 0) != 0)
49		return TC_ACT_SHOT;
50
51	if (bpf_skb_store_bytes(skb, 0, &src_mac, ETH_ALEN, 0) != 0)
52		return TC_ACT_SHOT;
53
54	if (bpf_skb_store_bytes(skb, ETH_ALEN, &dst_mac, ETH_ALEN, 0) != 0)
55		return TC_ACT_SHOT;
56
57	if (bpf_skb_store_bytes(skb, ETH_ALEN + ETH_ALEN, &proto, sizeof(__u16), 0) != 0)
58		return TC_ACT_SHOT;
59
60	return bpf_redirect_peer(IFINDEX_DST, 0);
61}
62
63char __license[] SEC("license") = "GPL";
64