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
13 volatile const __u32 IFINDEX_SRC;
14 volatile const __u32 IFINDEX_DST;
15
16 static const __u8 src_mac[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55};
17 static const __u8 dst_mac[] = {0x00, 0x22, 0x33, 0x44, 0x55, 0x66};
18
19 SEC("tc")
tc_chk(struct __sk_buff * skb)20 int tc_chk(struct __sk_buff *skb)
21 {
22 return TC_ACT_SHOT;
23 }
24
25 SEC("tc")
tc_dst(struct __sk_buff * skb)26 int tc_dst(struct __sk_buff *skb)
27 {
28 return bpf_redirect_peer(IFINDEX_SRC, 0);
29 }
30
31 SEC("tc")
tc_src(struct __sk_buff * skb)32 int tc_src(struct __sk_buff *skb)
33 {
34 return bpf_redirect_peer(IFINDEX_DST, 0);
35 }
36
37 SEC("tc")
tc_dst_ing(struct __sk_buff * skb)38 int tc_dst_ing(struct __sk_buff *skb)
39 {
40 if (!skb->mark) {
41 skb->mark = 0x1;
42 return bpf_redirect_peer(IFINDEX_SRC, BPF_F_EGRESS);
43 }
44
45 return bpf_redirect(IFINDEX_DST, 0);
46 }
47
48 SEC("tc")
tc_src_ing(struct __sk_buff * skb)49 int tc_src_ing(struct __sk_buff *skb)
50 {
51 if (!skb->mark) {
52 skb->mark = 0x1;
53 return bpf_redirect_peer(IFINDEX_DST, BPF_F_EGRESS);
54 }
55
56 return bpf_redirect(IFINDEX_SRC, 0);
57 }
58
59 SEC("tc")
tc_dst_l3(struct __sk_buff * skb)60 int tc_dst_l3(struct __sk_buff *skb)
61 {
62 return bpf_redirect(IFINDEX_SRC, 0);
63 }
64
65 SEC("tc")
tc_src_l3(struct __sk_buff * skb)66 int tc_src_l3(struct __sk_buff *skb)
67 {
68 __u16 proto = skb->protocol;
69
70 if (bpf_skb_change_head(skb, ETH_HLEN, 0) != 0)
71 return TC_ACT_SHOT;
72
73 if (bpf_skb_store_bytes(skb, 0, &src_mac, ETH_ALEN, 0) != 0)
74 return TC_ACT_SHOT;
75
76 if (bpf_skb_store_bytes(skb, ETH_ALEN, &dst_mac, ETH_ALEN, 0) != 0)
77 return TC_ACT_SHOT;
78
79 if (bpf_skb_store_bytes(skb, ETH_ALEN + ETH_ALEN, &proto, sizeof(__u16), 0) != 0)
80 return TC_ACT_SHOT;
81
82 return bpf_redirect_peer(IFINDEX_DST, 0);
83 }
84
85 char __license[] SEC("license") = "GPL";
86