summaryrefslogtreecommitdiffstats
path: root/net/netfilter/xt_CT.c
blob: ae7f5daeee4362bff5aee9a30a85347de70a2ccc (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
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
/*
 * Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_CT.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_l4proto.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_timeout.h>
#include <net/netfilter/nf_conntrack_zones.h>

static unsigned int xt_ct_target_v0(struct sk_buff *skb,
				    const struct xt_action_param *par)
{
	const struct xt_ct_target_info *info = par->targinfo;
	struct nf_conn *ct = info->ct;

	/* Previously seen (loopback)? Ignore. */
	if (skb->nfct != NULL)
		return XT_CONTINUE;

	atomic_inc(&ct->ct_general.use);
	skb->nfct = &ct->ct_general;
	skb->nfctinfo = IP_CT_NEW;

	return XT_CONTINUE;
}

static unsigned int xt_ct_target_v1(struct sk_buff *skb,
				    const struct xt_action_param *par)
{
	const struct xt_ct_target_info_v1 *info = par->targinfo;
	struct nf_conn *ct = info->ct;

	/* Previously seen (loopback)? Ignore. */
	if (skb->nfct != NULL)
		return XT_CONTINUE;

	atomic_inc(&ct->ct_general.use);
	skb->nfct = &ct->ct_general;
	skb->nfctinfo = IP_CT_NEW;

	return XT_CONTINUE;
}

static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
{
	if (par->family == NFPROTO_IPV4) {
		const struct ipt_entry *e = par->entryinfo;

		if (e->ip.invflags & IPT_INV_PROTO)
			return 0;
		return e->ip.proto;
	} else if (par->family == NFPROTO_IPV6) {
		const struct ip6t_entry *e = par->entryinfo;

		if (e->ipv6.invflags & IP6T_INV_PROTO)
			return 0;
		return e->ipv6.proto;
	} else
		return 0;
}

static int
xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
		 const struct xt_tgchk_param *par)
{
	struct nf_conntrack_helper *helper;
	struct nf_conn_help *help;
	u8 proto;

	proto = xt_ct_find_proto(par);
	if (!proto) {
		pr_info("You must specify a L4 protocol, and not use "
			"inversions on it.\n");
		return -ENOENT;
	}

	helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
						    proto);
	if (helper == NULL) {
		pr_info("No such helper \"%s\"\n", helper_name);
		return -ENOENT;
	}

	help = nf_ct_helper_ext_add(ct, helper, GFP_KERNEL);
	if (help == NULL) {
		module_put(helper->me);
		return -ENOMEM;
	}

	help->helper = helper;
	return 0;
}

static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
{
	struct xt_ct_target_info *info = par->targinfo;
	struct nf_conntrack_tuple t;
	struct nf_conn *ct;
	int ret;

	if (info->flags & ~XT_CT_NOTRACK)
		return -EINVAL;

	if (info->flags & XT_CT_NOTRACK) {
		ct = nf_ct_untracked_get();
		atomic_inc(&ct->ct_general.use);
		goto out;
	}

#ifndef CONFIG_NF_CONNTRACK_ZONES
	if (info->zone)
		goto err1;
#endif

	ret = nf_ct_l3proto_try_module_get(par->family);
	if (ret < 0)
		goto err1;

	memset(&t, 0, sizeof(t));
	ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
	ret = PTR_ERR(ct);
	if (IS_ERR(ct))
		goto err2;

	ret = 0;
	if ((info->ct_events || info->exp_events) &&
	    !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
				  GFP_KERNEL))
		goto err3;

	if (info->helper[0]) {
		ret = xt_ct_set_helper(ct, info->helper, par);
		if (ret < 0)
			goto err3;
	}

	__set_bit(IPS_TEMPLATE_BIT, &ct->status);
	__set_bit(IPS_CONFIRMED_BIT, &ct->status);
out:
	info->ct = ct;
	return 0;

err3:
	nf_conntrack_free(ct);
err2:
	nf_ct_l3proto_module_put(par->family);
err1:
	return ret;
}

#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
{
	typeof(nf_ct_timeout_put_hook) timeout_put;

	timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
	if (timeout_put)
		timeout_put(timeout);
}
#endif

static int
xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
		  const char *timeout_name)
{
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
	typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
	struct ctnl_timeout *timeout;
	struct nf_conn_timeout *timeout_ext;
	struct nf_conntrack_l4proto *l4proto;
	int ret = 0;
	u8 proto;

	rcu_read_lock();
	timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
	if (timeout_find_get == NULL) {
		ret = -ENOENT;
		pr_info("Timeout policy base is empty\n");
		goto out;
	}

	proto = xt_ct_find_proto(par);
	if (!proto) {
		ret = -EINVAL;
		pr_info("You must specify a L4 protocol, and not use "
			"inversions on it.\n");
		goto out;
	}

	timeout = timeout_find_get(timeout_name);
	if (timeout == NULL) {
		ret = -ENOENT;
		pr_info("No such timeout policy \"%s\"\n", timeout_name);
		goto out;
	}

	if (timeout->l3num != par->family) {
		ret = -EINVAL;
		pr_info("Timeout policy `%s' can only be used by L3 protocol "
			"number %d\n", timeout_name, timeout->l3num);
		goto err_put_timeout;
	}
	/* Make sure the timeout policy matches any existing protocol tracker,
	 * otherwise default to generic.
	 */
	l4proto = __nf_ct_l4proto_find(par->family, proto);
	if (timeout->l4proto->l4proto != l4proto->l4proto) {
		ret = -EINVAL;
		pr_info("Timeout policy `%s' can only be used by L4 protocol "
			"number %d\n",
			timeout_name, timeout->l4proto->l4proto);
		goto err_put_timeout;
	}
	timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
	if (timeout_ext == NULL)
		ret = -ENOMEM;

err_put_timeout:
	__xt_ct_tg_timeout_put(timeout);
out:
	rcu_read_unlock();
	return ret;
#else
	return -EOPNOTSUPP;
#endif
}

static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
{
	struct xt_ct_target_info_v1 *info = par->targinfo;
	struct nf_conntrack_tuple t;
	struct nf_conn *ct;
	int ret;

	if (info->flags & ~XT_CT_NOTRACK)
		return -EINVAL;

	if (info->flags & XT_CT_NOTRACK) {
		ct = nf_ct_untracked_get();
		atomic_inc(&ct->ct_general.use);
		goto out;
	}

#ifndef CONFIG_NF_CONNTRACK_ZONES
	if (info->zone)
		goto err1;
#endif

	ret = nf_ct_l3proto_try_module_get(par->family);
	if (ret < 0)
		goto err1;

	memset(&t, 0, sizeof(t));
	ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
	ret = PTR_ERR(ct);
	if (IS_ERR(ct))
		goto err2;

	ret = 0;
	if ((info->ct_events || info->exp_events) &&
	    !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
				  GFP_KERNEL))
		goto err3;

	if (info->helper[0]) {
		ret = xt_ct_set_helper(ct, info->helper, par);
		if (ret < 0)
			goto err3;
	}

	if (info->timeout[0]) {
		ret = xt_ct_set_timeout(ct, par, info->timeout);
		if (ret < 0)
			goto err3;
	}

	__set_bit(IPS_TEMPLATE_BIT, &ct->status);
	__set_bit(IPS_CONFIRMED_BIT, &ct->status);
out:
	info->ct = ct;
	return 0;

err3:
	nf_conntrack_free(ct);
err2:
	nf_ct_l3proto_module_put(par->family);
err1:
	return ret;
}

static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
{
	struct xt_ct_target_info *info = par->targinfo;
	struct nf_conn *ct = info->ct;
	struct nf_conn_help *help;

	if (!nf_ct_is_untracked(ct)) {
		help = nfct_help(ct);
		if (help)
			module_put(help->helper->me);

		nf_ct_l3proto_module_put(par->family);
	}
	nf_ct_put(info->ct);
}

static void xt_ct_destroy_timeout(struct nf_conn *ct)
{
#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
	struct nf_conn_timeout *timeout_ext;
	typeof(nf_ct_timeout_put_hook) timeout_put;

	rcu_read_lock();
	timeout_put = rcu_dereference(nf_ct_timeout_put_hook);

	if (timeout_put) {
		timeout_ext = nf_ct_timeout_find(ct);
		if (timeout_ext)
			timeout_put(timeout_ext->timeout);
	}
	rcu_read_unlock();
#endif
}

static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
{
	struct xt_ct_target_info_v1 *info = par->targinfo;
	struct nf_conn *ct = info->ct;
	struct nf_conn_help *help;

	if (!nf_ct_is_untracked(ct)) {
		help = nfct_help(ct);
		if (help)
			module_put(help->helper->me);

		nf_ct_l3proto_module_put(par->family);

		xt_ct_destroy_timeout(ct);
	}
	nf_ct_put(info->ct);
}

static struct xt_target xt_ct_tg_reg[] __read_mostly = {
	{
		.name		= "CT",
		.family		= NFPROTO_UNSPEC,
		.targetsize	= sizeof(struct xt_ct_target_info),
		.checkentry	= xt_ct_tg_check_v0,
		.destroy	= xt_ct_tg_destroy_v0,
		.target		= xt_ct_target_v0,
		.table		= "raw",
		.me		= THIS_MODULE,
	},
	{
		.name		= "CT",
		.family		= NFPROTO_UNSPEC,
		.revision	= 1,
		.targetsize	= sizeof(struct xt_ct_target_info_v1),
		.checkentry	= xt_ct_tg_check_v1,
		.destroy	= xt_ct_tg_destroy_v1,
		.target		= xt_ct_target_v1,
		.table		= "raw",
		.me		= THIS_MODULE,
	},
};

static int __init xt_ct_tg_init(void)
{
	return xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
}

static void __exit xt_ct_tg_exit(void)
{
	xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
}

module_init(xt_ct_tg_init);
module_exit(xt_ct_tg_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: connection tracking target");
MODULE_ALIAS("ipt_CT");
MODULE_ALIAS("ip6t_CT");