tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2018 Facebook
3
4#include <linux/stddef.h>
5#include <linux/bpf.h>
6#include <sys/socket.h>
7
8#include <bpf/bpf_helpers.h>
9#include <bpf/bpf_endian.h>
10
11#include <bpf_sockopt_helpers.h>
12
13#define SRC_REWRITE_IP6_0 0
14#define SRC_REWRITE_IP6_1 0
15#define SRC_REWRITE_IP6_2 0
16#define SRC_REWRITE_IP6_3 6
17
18#define DST_REWRITE_IP6_0 0
19#define DST_REWRITE_IP6_1 0
20#define DST_REWRITE_IP6_2 0
21#define DST_REWRITE_IP6_3 1
22
23#define DST_REWRITE_IP6_V4_MAPPED_0 0
24#define DST_REWRITE_IP6_V4_MAPPED_1 0
25#define DST_REWRITE_IP6_V4_MAPPED_2 0x0000FFFF
26#define DST_REWRITE_IP6_V4_MAPPED_3 0xc0a80004 // 192.168.0.4
27
28#define DST_REWRITE_PORT6 6666
29
30SEC("cgroup/sendmsg6")
31int sendmsg_v6_prog(struct bpf_sock_addr *ctx)
32{
33 if (ctx->type != SOCK_DGRAM)
34 return 0;
35
36 if (!get_set_sk_priority(ctx))
37 return 0;
38
39 /* Rewrite source. */
40 if (ctx->msg_src_ip6[3] == bpf_htonl(1) ||
41 ctx->msg_src_ip6[3] == bpf_htonl(0)) {
42 ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
43 ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
44 ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
45 ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
46 } else {
47 /* Unexpected source. Reject sendmsg. */
48 return 0;
49 }
50
51 /* Rewrite destination. */
52 if (ctx->user_ip6[0] == bpf_htonl(0xFACEB00C)) {
53 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_0);
54 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_1);
55 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_2);
56 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_3);
57
58 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
59 } else {
60 /* Unexpected destination. Reject sendmsg. */
61 return 0;
62 }
63
64 return 1;
65}
66
67SEC("cgroup/sendmsg6")
68int sendmsg_v6_v4mapped_prog(struct bpf_sock_addr *ctx)
69{
70 /* Rewrite source. */
71 ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
72 ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
73 ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
74 ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
75
76 /* Rewrite destination. */
77 ctx->user_ip6[0] = bpf_htonl(DST_REWRITE_IP6_V4_MAPPED_0);
78 ctx->user_ip6[1] = bpf_htonl(DST_REWRITE_IP6_V4_MAPPED_1);
79 ctx->user_ip6[2] = bpf_htonl(DST_REWRITE_IP6_V4_MAPPED_2);
80 ctx->user_ip6[3] = bpf_htonl(DST_REWRITE_IP6_V4_MAPPED_3);
81
82 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
83
84 return 1;
85}
86
87SEC("cgroup/sendmsg6")
88int sendmsg_v6_wildcard_prog(struct bpf_sock_addr *ctx)
89{
90 /* Rewrite source. */
91 ctx->msg_src_ip6[0] = bpf_htonl(SRC_REWRITE_IP6_0);
92 ctx->msg_src_ip6[1] = bpf_htonl(SRC_REWRITE_IP6_1);
93 ctx->msg_src_ip6[2] = bpf_htonl(SRC_REWRITE_IP6_2);
94 ctx->msg_src_ip6[3] = bpf_htonl(SRC_REWRITE_IP6_3);
95
96 /* Rewrite destination. */
97 ctx->user_ip6[0] = bpf_htonl(0);
98 ctx->user_ip6[1] = bpf_htonl(0);
99 ctx->user_ip6[2] = bpf_htonl(0);
100 ctx->user_ip6[3] = bpf_htonl(0);
101
102 ctx->user_port = bpf_htons(DST_REWRITE_PORT6);
103
104 return 1;
105}
106
107SEC("cgroup/sendmsg6")
108int sendmsg_v6_preserve_dst_prog(struct bpf_sock_addr *ctx)
109{
110 return 1;
111}
112
113SEC("cgroup/sendmsg6")
114int sendmsg_v6_deny_prog(struct bpf_sock_addr *ctx)
115{
116 return 0;
117}
118
119char _license[] SEC("license") = "GPL";