1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <stddef.h> |
3 | #include <string.h> |
4 | #include <linux/bpf.h> |
5 | #include <linux/ip.h> |
6 | #include <linux/ipv6.h> |
7 | #include <bpf/bpf_helpers.h> |
8 | #include <bpf/bpf_endian.h> |
9 | |
10 | struct grehdr { |
11 | __be16 flags; |
12 | __be16 protocol; |
13 | }; |
14 | |
15 | SEC("encap_gre" ) |
16 | int bpf_lwt_encap_gre(struct __sk_buff *skb) |
17 | { |
18 | struct encap_hdr { |
19 | struct iphdr iph; |
20 | struct grehdr greh; |
21 | } hdr; |
22 | int err; |
23 | |
24 | memset(&hdr, 0, sizeof(struct encap_hdr)); |
25 | |
26 | hdr.iph.ihl = 5; |
27 | hdr.iph.version = 4; |
28 | hdr.iph.ttl = 0x40; |
29 | hdr.iph.protocol = 47; /* IPPROTO_GRE */ |
30 | #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ |
31 | hdr.iph.saddr = 0x640110ac; /* 172.16.1.100 */ |
32 | hdr.iph.daddr = 0x641010ac; /* 172.16.16.100 */ |
33 | #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ |
34 | hdr.iph.saddr = 0xac100164; /* 172.16.1.100 */ |
35 | hdr.iph.daddr = 0xac101064; /* 172.16.16.100 */ |
36 | #else |
37 | #error "Fix your compiler's __BYTE_ORDER__?!" |
38 | #endif |
39 | hdr.iph.tot_len = bpf_htons(skb->len + sizeof(struct encap_hdr)); |
40 | |
41 | hdr.greh.protocol = skb->protocol; |
42 | |
43 | err = bpf_lwt_push_encap(skb, BPF_LWT_ENCAP_IP, &hdr, |
44 | sizeof(struct encap_hdr)); |
45 | if (err) |
46 | return BPF_DROP; |
47 | |
48 | return BPF_LWT_REROUTE; |
49 | } |
50 | |
51 | SEC("encap_gre6" ) |
52 | int bpf_lwt_encap_gre6(struct __sk_buff *skb) |
53 | { |
54 | struct encap_hdr { |
55 | struct ipv6hdr ip6hdr; |
56 | struct grehdr greh; |
57 | } hdr; |
58 | int err; |
59 | |
60 | memset(&hdr, 0, sizeof(struct encap_hdr)); |
61 | |
62 | hdr.ip6hdr.version = 6; |
63 | hdr.ip6hdr.payload_len = bpf_htons(skb->len + sizeof(struct grehdr)); |
64 | hdr.ip6hdr.nexthdr = 47; /* IPPROTO_GRE */ |
65 | hdr.ip6hdr.hop_limit = 0x40; |
66 | /* fb01::1 */ |
67 | hdr.ip6hdr.saddr.s6_addr[0] = 0xfb; |
68 | hdr.ip6hdr.saddr.s6_addr[1] = 1; |
69 | hdr.ip6hdr.saddr.s6_addr[15] = 1; |
70 | /* fb10::1 */ |
71 | hdr.ip6hdr.daddr.s6_addr[0] = 0xfb; |
72 | hdr.ip6hdr.daddr.s6_addr[1] = 0x10; |
73 | hdr.ip6hdr.daddr.s6_addr[15] = 1; |
74 | |
75 | hdr.greh.protocol = skb->protocol; |
76 | |
77 | err = bpf_lwt_push_encap(skb, BPF_LWT_ENCAP_IP, &hdr, |
78 | sizeof(struct encap_hdr)); |
79 | if (err) |
80 | return BPF_DROP; |
81 | |
82 | return BPF_LWT_REROUTE; |
83 | } |
84 | |
85 | char _license[] SEC("license" ) = "GPL" ; |
86 | |