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
27int _version SEC("version") = 1;
28
29SEC("cgroup/connect6")
30int 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
95char _license[] SEC("license") = "GPL";
96