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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_helpers.h"
13#include "bpf_endian.h"
14
15#define SRC_REWRITE_IP4 0x7f000004U
16#define DST_REWRITE_IP4 0x7f000001U
17#define DST_REWRITE_PORT4 4444
18
19int _version SEC("version") = 1;
20
21SEC("cgroup/connect4")
22int connect_v4_prog(struct bpf_sock_addr *ctx)
23{
24 struct bpf_sock_tuple tuple = {};
25 struct sockaddr_in sa;
26 struct bpf_sock *sk;
27
28 /* Verify that new destination is available. */
29 memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));
30 memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));
31
32 tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);
33 tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);
34
35 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
36 return 0;
37 else if (ctx->type == SOCK_STREAM)
38 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4),
39 BPF_F_CURRENT_NETNS, 0);
40 else
41 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4),
42 BPF_F_CURRENT_NETNS, 0);
43
44 if (!sk)
45 return 0;
46
47 if (sk->src_ip4 != tuple.ipv4.daddr ||
48 sk->src_port != DST_REWRITE_PORT4) {
49 bpf_sk_release(sk);
50 return 0;
51 }
52
53 bpf_sk_release(sk);
54
55 /* Rewrite destination. */
56 ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
57 ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
58
59 /* Rewrite source. */
60 memset(&sa, 0, sizeof(sa));
61
62 sa.sin_family = AF_INET;
63 sa.sin_port = bpf_htons(0);
64 sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
65
66 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
67 return 0;
68
69 return 1;
70}
71
72char _license[] SEC("license") = "GPL";
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 <linux/tcp.h>
11#include <linux/if.h>
12#include <errno.h>
13
14#include <bpf/bpf_helpers.h>
15#include <bpf/bpf_endian.h>
16
17#include "bpf_tcp_helpers.h"
18
19#define SRC_REWRITE_IP4 0x7f000004U
20#define DST_REWRITE_IP4 0x7f000001U
21#define DST_REWRITE_PORT4 4444
22
23#ifndef TCP_CA_NAME_MAX
24#define TCP_CA_NAME_MAX 16
25#endif
26
27#ifndef TCP_NOTSENT_LOWAT
28#define TCP_NOTSENT_LOWAT 25
29#endif
30
31#ifndef IFNAMSIZ
32#define IFNAMSIZ 16
33#endif
34
35__attribute__ ((noinline))
36int do_bind(struct bpf_sock_addr *ctx)
37{
38 struct sockaddr_in sa = {};
39
40 sa.sin_family = AF_INET;
41 sa.sin_port = bpf_htons(0);
42 sa.sin_addr.s_addr = bpf_htonl(SRC_REWRITE_IP4);
43
44 if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
45 return 0;
46
47 return 1;
48}
49
50static __inline int verify_cc(struct bpf_sock_addr *ctx,
51 char expected[TCP_CA_NAME_MAX])
52{
53 char buf[TCP_CA_NAME_MAX];
54 int i;
55
56 if (bpf_getsockopt(ctx, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))
57 return 1;
58
59 for (i = 0; i < TCP_CA_NAME_MAX; i++) {
60 if (buf[i] != expected[i])
61 return 1;
62 if (buf[i] == 0)
63 break;
64 }
65
66 return 0;
67}
68
69static __inline int set_cc(struct bpf_sock_addr *ctx)
70{
71 char reno[TCP_CA_NAME_MAX] = "reno";
72 char cubic[TCP_CA_NAME_MAX] = "cubic";
73
74 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &reno, sizeof(reno)))
75 return 1;
76 if (verify_cc(ctx, reno))
77 return 1;
78
79 if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &cubic, sizeof(cubic)))
80 return 1;
81 if (verify_cc(ctx, cubic))
82 return 1;
83
84 return 0;
85}
86
87static __inline int bind_to_device(struct bpf_sock_addr *ctx)
88{
89 char veth1[IFNAMSIZ] = "test_sock_addr1";
90 char veth2[IFNAMSIZ] = "test_sock_addr2";
91 char missing[IFNAMSIZ] = "nonexistent_dev";
92 char del_bind[IFNAMSIZ] = "";
93
94 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
95 &veth1, sizeof(veth1)))
96 return 1;
97 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
98 &veth2, sizeof(veth2)))
99 return 1;
100 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
101 &missing, sizeof(missing)) != -ENODEV)
102 return 1;
103 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_BINDTODEVICE,
104 &del_bind, sizeof(del_bind)))
105 return 1;
106
107 return 0;
108}
109
110static __inline int set_keepalive(struct bpf_sock_addr *ctx)
111{
112 int zero = 0, one = 1;
113
114 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof(one)))
115 return 1;
116 if (ctx->type == SOCK_STREAM) {
117 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPIDLE, &one, sizeof(one)))
118 return 1;
119 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPINTVL, &one, sizeof(one)))
120 return 1;
121 if (bpf_setsockopt(ctx, SOL_TCP, TCP_KEEPCNT, &one, sizeof(one)))
122 return 1;
123 if (bpf_setsockopt(ctx, SOL_TCP, TCP_SYNCNT, &one, sizeof(one)))
124 return 1;
125 if (bpf_setsockopt(ctx, SOL_TCP, TCP_USER_TIMEOUT, &one, sizeof(one)))
126 return 1;
127 }
128 if (bpf_setsockopt(ctx, SOL_SOCKET, SO_KEEPALIVE, &zero, sizeof(zero)))
129 return 1;
130
131 return 0;
132}
133
134static __inline int set_notsent_lowat(struct bpf_sock_addr *ctx)
135{
136 int lowat = 65535;
137
138 if (ctx->type == SOCK_STREAM) {
139 if (bpf_setsockopt(ctx, SOL_TCP, TCP_NOTSENT_LOWAT, &lowat, sizeof(lowat)))
140 return 1;
141 }
142
143 return 0;
144}
145
146SEC("cgroup/connect4")
147int connect_v4_prog(struct bpf_sock_addr *ctx)
148{
149 struct bpf_sock_tuple tuple = {};
150 struct bpf_sock *sk;
151
152 /* Verify that new destination is available. */
153 memset(&tuple.ipv4.saddr, 0, sizeof(tuple.ipv4.saddr));
154 memset(&tuple.ipv4.sport, 0, sizeof(tuple.ipv4.sport));
155
156 tuple.ipv4.daddr = bpf_htonl(DST_REWRITE_IP4);
157 tuple.ipv4.dport = bpf_htons(DST_REWRITE_PORT4);
158
159 /* Bind to device and unbind it. */
160 if (bind_to_device(ctx))
161 return 0;
162
163 if (set_keepalive(ctx))
164 return 0;
165
166 if (set_notsent_lowat(ctx))
167 return 0;
168
169 if (ctx->type != SOCK_STREAM && ctx->type != SOCK_DGRAM)
170 return 0;
171 else if (ctx->type == SOCK_STREAM)
172 sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple.ipv4),
173 BPF_F_CURRENT_NETNS, 0);
174 else
175 sk = bpf_sk_lookup_udp(ctx, &tuple, sizeof(tuple.ipv4),
176 BPF_F_CURRENT_NETNS, 0);
177
178 if (!sk)
179 return 0;
180
181 if (sk->src_ip4 != tuple.ipv4.daddr ||
182 sk->src_port != DST_REWRITE_PORT4) {
183 bpf_sk_release(sk);
184 return 0;
185 }
186
187 bpf_sk_release(sk);
188
189 /* Rewrite congestion control. */
190 if (ctx->type == SOCK_STREAM && set_cc(ctx))
191 return 0;
192
193 /* Rewrite destination. */
194 ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
195 ctx->user_port = bpf_htons(DST_REWRITE_PORT4);
196
197 return do_bind(ctx) ? 1 : 0;
198}
199
200char _license[] SEC("license") = "GPL";