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 SEC("cgroup/connect6")
28 int connect_v6_prog(struct bpf_sock_addr *ctx)
29 {
30 struct bpf_sock_tuple tuple = {};
31 struct sockaddr_in6 sa;
32 struct bpf_sock *sk;
33
34 /* Verify that new destination is available. */
35 memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr));
36 memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport));
37
38 tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0);
39 tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1);
40 tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2);
41 tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3);
42
43 tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6);
44
45 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
46 return 0;
47 else if (ctx->type == SOCK_STREAM)
48 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6),
49 BPF_F_CURRENT_NETNS, 0);
50 else
51 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6),
52 BPF_F_CURRENT_NETNS, 0);
53
54 if (!sk)
55 return 0;
56
57 if (sk->src_ip6[0] != tuple.ipv6.daddr[0] ||
58 sk->src_ip6[1] != tuple.ipv6.daddr[1] ||
59 sk->src_ip6[2] != tuple.ipv6.daddr[2] ||
60 sk->src_ip6[3] != tuple.ipv6.daddr[3] ||
61 sk->src_port != DST_REWRITE_PORT6) {
62 bpf_sk_release(sk);
63 return 0;
64 }
65
66 bpf_sk_release(sk);
67
68 /* Rewrite destination. */
69 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
70 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
71 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
72 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
73
74 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
75
76 /* Rewrite source. */
77 memset(&sa, 0, sizeof(sa));
78
79 sa.sin6_family = AF_INET6;
80 sa.sin6_port = bpf_htons(0);
81
82 sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
83 sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
84 sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
85 sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
86
87 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
88 return 0;
89
90 return 1;
91 }
92
93 SEC("cgroup/connect6")
94 int connect_v6_deny_prog(struct bpf_sock_addr *ctx)
95 {
96 return 0;
97 }
98
99 char _license[] SEC("license") = "GPL";
100
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