1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (c) 2018 Facebook
3
4 #include <string.h>
5
6 #include <linux/stddef.h>
7 #include <linux/bpf.h>
8 #include <linux/in.h>
9 #include <linux/in6.h>
10 #include <sys/socket.h>
11
12 #include <bpf/bpf_helpers.h>
13 #include <bpf/bpf_endian.h>
14
15 #define SRC_REWRITE_IP6_0 0
16 #define SRC_REWRITE_IP6_1 0
17 #define SRC_REWRITE_IP6_2 0
18 #define SRC_REWRITE_IP6_3 6
19
20 #define DST_REWRITE_IP6_0 0
21 #define DST_REWRITE_IP6_1 0
22 #define DST_REWRITE_IP6_2 0
23 #define DST_REWRITE_IP6_3 1
24
25 #define DST_REWRITE_PORT6 6666
26
27 int _version SEC("version") = 1;
28
29 SEC("cgroup/connect6")
connect_v6_prog(struct bpf_sock_addr * ctx)30 int connect_v6_prog(struct bpf_sock_addr *ctx)
31 {
32 struct bpf_sock_tuple tuple = {};
33 struct sockaddr_in6 sa;
34 struct bpf_sock *sk;
35
36 /* Verify that new destination is available. */
37 memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr));
38 memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport));
39
40 tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0);
41 tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1);
42 tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2);
43 tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3);
44
45 tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6);
46
47 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
48 return 0;
49 else if (ctx->type == SOCK_STREAM)
50 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6),
51 BPF_F_CURRENT_NETNS, 0);
52 else
53 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6),
54 BPF_F_CURRENT_NETNS, 0);
55
56 if (!sk)
57 return 0;
58
59 if (sk->src_ip6[0] != tuple.ipv6.daddr[0] ||
60 sk->src_ip6[1] != tuple.ipv6.daddr[1] ||
61 sk->src_ip6[2] != tuple.ipv6.daddr[2] ||
62 sk->src_ip6[3] != tuple.ipv6.daddr[3] ||
63 sk->src_port != DST_REWRITE_PORT6) {
64 bpf_sk_release(sk);
65 return 0;
66 }
67
68 bpf_sk_release(sk);
69
70 /* Rewrite destination. */
71 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
72 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
73 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
74 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
75
76 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
77
78 /* Rewrite source. */
79 memset(&sa, 0, sizeof(sa));
80
81 sa.sin6_family = AF_INET6;
82 sa.sin6_port = bpf_htons(0);
83
84 sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
85 sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
86 sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
87 sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
88
89 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
90 return 0;
91
92 return 1;
93 }
94
95 char _license[] SEC("license") = "GPL";
96
