summaryrefslogtreecommitdiff
path: root/net/netfilter/xt_socket.c
blob: 76e01f292aaff638f8c9c37583bc33b3ea942b65 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Transparent proxy support for Linux/iptables
 *
 * Copyright (C) 2007-2008 BalaBit IT Ltd.
 * Author: Krisztian Kovacs
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <net/tcp.h>
#include <net/udp.h>
#include <net/icmp.h>
#include <net/sock.h>
#include <net/inet_sock.h>
#include <net/netfilter/ipv4/nf_defrag_ipv4.h>

#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <net/inet6_hashtables.h>
#include <net/netfilter/ipv6/nf_defrag_ipv6.h>
#endif

#include <net/netfilter/nf_socket.h>
#include <linux/netfilter/xt_socket.h>

/* "socket" match based redirection (no specific rule)
 * ===================================================
 *
 * There are connections with dynamic endpoints (e.g. FTP data
 * connection) that the user is unable to add explicit rules
 * for. These are taken care of by a generic "socket" rule. It is
 * assumed that the proxy application is trusted to open such
 * connections without explicit iptables rule (except of course the
 * generic 'socket' rule). In this case the following sockets are
 * matched in preference order:
 *
 *   - match: if there's a fully established connection matching the
 *     _packet_ tuple
 *
 *   - match: if there's a non-zero bound listener (possibly with a
 *     non-local address) We don't accept zero-bound listeners, since
 *     then local services could intercept traffic going through the
 *     box.
 */
static bool
socket_match(const struct sk_buff *skb, struct xt_action_param *par,
	     const struct xt_socket_mtinfo1 *info)
{
	struct sk_buff *pskb = (struct sk_buff *)skb;
	struct sock *sk = skb->sk;

	if (sk && !net_eq(xt_net(par), sock_net(sk)))
		sk = NULL;

	if (!sk)
		sk = nf_sk_lookup_slow_v4(xt_net(par), skb, xt_in(par));

	if (sk) {
		bool wildcard;
		bool transparent = true;

		/* Ignore sockets listening on INADDR_ANY,
		 * unless XT_SOCKET_NOWILDCARD is set
		 */
		wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
			    sk_fullsock(sk) &&
			    inet_sk(sk)->inet_rcv_saddr == 0);

		/* Ignore non-transparent sockets,
		 * if XT_SOCKET_TRANSPARENT is used
		 */
		if (info->flags & XT_SOCKET_TRANSPARENT)
			transparent = inet_sk_transparent(sk);

		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
		    transparent && sk_fullsock(sk))
			pskb->mark = READ_ONCE(sk->sk_mark);

		if (sk != skb->sk)
			sock_gen_put(sk);

		if (wildcard || !transparent)
			sk = NULL;
	}

	return sk != NULL;
}

static bool
socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par)
{
	static struct xt_socket_mtinfo1 xt_info_v0 = {
		.flags = 0,
	};

	return socket_match(skb, par, &xt_info_v0);
}

static bool
socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
{
	return socket_match(skb, par, par->matchinfo);
}

#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
static bool
socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
	struct sk_buff *pskb = (struct sk_buff *)skb;
	struct sock *sk = skb->sk;

	if (sk && !net_eq(xt_net(par), sock_net(sk)))
		sk = NULL;

	if (!sk)
		sk = nf_sk_lookup_slow_v6(xt_net(par), skb, xt_in(par));

	if (sk) {
		bool wildcard;
		bool transparent = true;

		/* Ignore sockets listening on INADDR_ANY
		 * unless XT_SOCKET_NOWILDCARD is set
		 */
		wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) &&
			    sk_fullsock(sk) &&
			    ipv6_addr_any(&sk->sk_v6_rcv_saddr));

		/* Ignore non-transparent sockets,
		 * if XT_SOCKET_TRANSPARENT is used
		 */
		if (info->flags & XT_SOCKET_TRANSPARENT)
			transparent = inet_sk_transparent(sk);

		if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard &&
		    transparent && sk_fullsock(sk))
			pskb->mark = READ_ONCE(sk->sk_mark);

		if (sk != skb->sk)
			sock_gen_put(sk);

		if (wildcard || !transparent)
			sk = NULL;
	}

	return sk != NULL;
}
#endif

static int socket_mt_enable_defrag(struct net *net, int family)
{
	switch (family) {
	case NFPROTO_IPV4:
		return nf_defrag_ipv4_enable(net);
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	case NFPROTO_IPV6:
		return nf_defrag_ipv6_enable(net);
#endif
	}
	WARN_ONCE(1, "Unknown family %d\n", family);
	return 0;
}

static int socket_mt_v1_check(const struct xt_mtchk_param *par)
{
	const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo;
	int err;

	err = socket_mt_enable_defrag(par->net, par->family);
	if (err)
		return err;

	if (info->flags & ~XT_SOCKET_FLAGS_V1) {
		pr_info_ratelimited("unknown flags 0x%x\n",
				    info->flags & ~XT_SOCKET_FLAGS_V1);
		return -EINVAL;
	}
	return 0;
}

static int socket_mt_v2_check(const struct xt_mtchk_param *par)
{
	const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo;
	int err;

	err = socket_mt_enable_defrag(par->net, par->family);
	if (err)
		return err;

	if (info->flags & ~XT_SOCKET_FLAGS_V2) {
		pr_info_ratelimited("unknown flags 0x%x\n",
				    info->flags & ~XT_SOCKET_FLAGS_V2);
		return -EINVAL;
	}
	return 0;
}

static int socket_mt_v3_check(const struct xt_mtchk_param *par)
{
	const struct xt_socket_mtinfo3 *info =
				    (struct xt_socket_mtinfo3 *)par->matchinfo;
	int err;

	err = socket_mt_enable_defrag(par->net, par->family);
	if (err)
		return err;
	if (info->flags & ~XT_SOCKET_FLAGS_V3) {
		pr_info_ratelimited("unknown flags 0x%x\n",
				    info->flags & ~XT_SOCKET_FLAGS_V3);
		return -EINVAL;
	}
	return 0;
}

static void socket_mt_destroy(const struct xt_mtdtor_param *par)
{
	if (par->family == NFPROTO_IPV4)
		nf_defrag_ipv4_disable(par->net);
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	else if (par->family == NFPROTO_IPV6)
		nf_defrag_ipv6_disable(par->net);
#endif
}

static struct xt_match socket_mt_reg[] __read_mostly = {
	{
		.name		= "socket",
		.revision	= 0,
		.family		= NFPROTO_IPV4,
		.match		= socket_mt4_v0,
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
	{
		.name		= "socket",
		.revision	= 1,
		.family		= NFPROTO_IPV4,
		.match		= socket_mt4_v1_v2_v3,
		.destroy	= socket_mt_destroy,
		.checkentry	= socket_mt_v1_check,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	{
		.name		= "socket",
		.revision	= 1,
		.family		= NFPROTO_IPV6,
		.match		= socket_mt6_v1_v2_v3,
		.checkentry	= socket_mt_v1_check,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.destroy	= socket_mt_destroy,
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#endif
	{
		.name		= "socket",
		.revision	= 2,
		.family		= NFPROTO_IPV4,
		.match		= socket_mt4_v1_v2_v3,
		.checkentry	= socket_mt_v2_check,
		.destroy	= socket_mt_destroy,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	{
		.name		= "socket",
		.revision	= 2,
		.family		= NFPROTO_IPV6,
		.match		= socket_mt6_v1_v2_v3,
		.checkentry	= socket_mt_v2_check,
		.destroy	= socket_mt_destroy,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#endif
	{
		.name		= "socket",
		.revision	= 3,
		.family		= NFPROTO_IPV4,
		.match		= socket_mt4_v1_v2_v3,
		.checkentry	= socket_mt_v3_check,
		.destroy	= socket_mt_destroy,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
	{
		.name		= "socket",
		.revision	= 3,
		.family		= NFPROTO_IPV6,
		.match		= socket_mt6_v1_v2_v3,
		.checkentry	= socket_mt_v3_check,
		.destroy	= socket_mt_destroy,
		.matchsize	= sizeof(struct xt_socket_mtinfo1),
		.hooks		= (1 << NF_INET_PRE_ROUTING) |
				  (1 << NF_INET_LOCAL_IN),
		.me		= THIS_MODULE,
	},
#endif
};

static int __init socket_mt_init(void)
{
	return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
}

static void __exit socket_mt_exit(void)
{
	xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg));
}

module_init(socket_mt_init);
module_exit(socket_mt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
MODULE_DESCRIPTION("x_tables socket match module");
MODULE_ALIAS("ipt_socket");
MODULE_ALIAS("ip6t_socket");