1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun // Copyright (c) 2018 Facebook
3*4882a593Smuzhiyun
4*4882a593Smuzhiyun #include <string.h>
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun #include <linux/stddef.h>
7*4882a593Smuzhiyun #include <linux/bpf.h>
8*4882a593Smuzhiyun #include <linux/in.h>
9*4882a593Smuzhiyun #include <linux/in6.h>
10*4882a593Smuzhiyun #include <sys/socket.h>
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #include <bpf/bpf_helpers.h>
13*4882a593Smuzhiyun #include <bpf/bpf_endian.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #define SRC_REWRITE_IP6_0 0
16*4882a593Smuzhiyun #define SRC_REWRITE_IP6_1 0
17*4882a593Smuzhiyun #define SRC_REWRITE_IP6_2 0
18*4882a593Smuzhiyun #define SRC_REWRITE_IP6_3 6
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun #define DST_REWRITE_IP6_0 0
21*4882a593Smuzhiyun #define DST_REWRITE_IP6_1 0
22*4882a593Smuzhiyun #define DST_REWRITE_IP6_2 0
23*4882a593Smuzhiyun #define DST_REWRITE_IP6_3 1
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun #define DST_REWRITE_PORT6 6666
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun int _version SEC("version") = 1;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun SEC("cgroup/connect6")
connect_v6_prog(struct bpf_sock_addr * ctx)30*4882a593Smuzhiyun int connect_v6_prog(struct bpf_sock_addr *ctx)
31*4882a593Smuzhiyun {
32*4882a593Smuzhiyun struct bpf_sock_tuple tuple = {};
33*4882a593Smuzhiyun struct sockaddr_in6 sa;
34*4882a593Smuzhiyun struct bpf_sock *sk;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun /* Verify that new destination is available. */
37*4882a593Smuzhiyun memset(&tuple.ipv6.saddr, 0, sizeof(tuple.ipv6.saddr));
38*4882a593Smuzhiyun memset(&tuple.ipv6.sport, 0, sizeof(tuple.ipv6.sport));
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun tuple.ipv6.daddr[0] = bpf_htonl(DST_REWRITE_IP6_0);
41*4882a593Smuzhiyun tuple.ipv6.daddr[1] = bpf_htonl(DST_REWRITE_IP6_1);
42*4882a593Smuzhiyun tuple.ipv6.daddr[2] = bpf_htonl(DST_REWRITE_IP6_2);
43*4882a593Smuzhiyun tuple.ipv6.daddr[3] = bpf_htonl(DST_REWRITE_IP6_3);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun tuple.ipv6.dport = bpf_htons(DST_REWRITE_PORT6);
46*4882a593Smuzhiyun
47*4882a593Smuzhiyun if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
48*4882a593Smuzhiyun return 0;
49*4882a593Smuzhiyun else if (ctx->type == SOCK_STREAM)
50*4882a593Smuzhiyun sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv6),
51*4882a593Smuzhiyun BPF_F_CURRENT_NETNS, 0);
52*4882a593Smuzhiyun else
53*4882a593Smuzhiyun sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv6),
54*4882a593Smuzhiyun BPF_F_CURRENT_NETNS, 0);
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun if (!sk)
57*4882a593Smuzhiyun return 0;
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun if (sk->src_ip6[0] != tuple.ipv6.daddr[0] ||
60*4882a593Smuzhiyun sk->src_ip6[1] != tuple.ipv6.daddr[1] ||
61*4882a593Smuzhiyun sk->src_ip6[2] != tuple.ipv6.daddr[2] ||
62*4882a593Smuzhiyun sk->src_ip6[3] != tuple.ipv6.daddr[3] ||
63*4882a593Smuzhiyun sk->src_port != DST_REWRITE_PORT6) {
64*4882a593Smuzhiyun bpf_sk_release(sk);
65*4882a593Smuzhiyun return 0;
66*4882a593Smuzhiyun }
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun bpf_sk_release(sk);
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun /* Rewrite destination. */
71*4882a593Smuzhiyun ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
72*4882a593Smuzhiyun ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
73*4882a593Smuzhiyun ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
74*4882a593Smuzhiyun ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun /* Rewrite source. */
79*4882a593Smuzhiyun memset(&sa, 0, sizeof(sa));
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun sa.sin6_family = AF_INET6;
82*4882a593Smuzhiyun sa.sin6_port = bpf_htons(0);
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun sa.sin6_addr.s6_addr32[0] = bpf_htonl(SRC_REWRITE_IP6_0);
85*4882a593Smuzhiyun sa.sin6_addr.s6_addr32[1] = bpf_htonl(SRC_REWRITE_IP6_1);
86*4882a593Smuzhiyun sa.sin6_addr.s6_addr32[2] = bpf_htonl(SRC_REWRITE_IP6_2);
87*4882a593Smuzhiyun sa.sin6_addr.s6_addr32[3] = bpf_htonl(SRC_REWRITE_IP6_3);
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
90*4882a593Smuzhiyun return 0;
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun return 1;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
96