1/*
2 *	xt_conntrack - Netfilter module to match connection tracking
3 *	information. (Superset of Rusty's minimalistic state match.)
4 *
5 *	(C) 2001  Marc Boucher (marc@mbsi.ca).
6 *	(C) 2006-2012 Patrick McHardy <kaber@trash.net>
7 *	Copyright �� CC Computer Consultants GmbH, 2007 - 2008
8 *
9 *	This program is free software; you can redistribute it and/or modify
10 *	it under the terms of the GNU General Public License version 2 as
11 *	published by the Free Software Foundation.
12 */
13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14#include <linux/module.h>
15#include <linux/skbuff.h>
16#include <net/ipv6.h>
17#include <linux/netfilter/x_tables.h>
18#include <linux/netfilter/xt_conntrack.h>
19#include <net/netfilter/nf_conntrack.h>
20
21MODULE_LICENSE("GPL");
22MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
23MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
24MODULE_DESCRIPTION("Xtables: connection tracking state match");
25MODULE_ALIAS("ipt_conntrack");
26MODULE_ALIAS("ip6t_conntrack");
27
28static bool
29conntrack_addrcmp(const union nf_inet_addr *kaddr,
30                  const union nf_inet_addr *uaddr,
31                  const union nf_inet_addr *umask, unsigned int l3proto)
32{
33	if (l3proto == NFPROTO_IPV4)
34		return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
35	else if (l3proto == NFPROTO_IPV6)
36		return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
37		       &uaddr->in6) == 0;
38	else
39		return false;
40}
41
42static inline bool
43conntrack_mt_origsrc(const struct nf_conn *ct,
44                     const struct xt_conntrack_mtinfo2 *info,
45		     u_int8_t family)
46{
47	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
48	       &info->origsrc_addr, &info->origsrc_mask, family);
49}
50
51static inline bool
52conntrack_mt_origdst(const struct nf_conn *ct,
53                     const struct xt_conntrack_mtinfo2 *info,
54		     u_int8_t family)
55{
56	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
57	       &info->origdst_addr, &info->origdst_mask, family);
58}
59
60static inline bool
61conntrack_mt_replsrc(const struct nf_conn *ct,
62                     const struct xt_conntrack_mtinfo2 *info,
63		     u_int8_t family)
64{
65	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
66	       &info->replsrc_addr, &info->replsrc_mask, family);
67}
68
69static inline bool
70conntrack_mt_repldst(const struct nf_conn *ct,
71                     const struct xt_conntrack_mtinfo2 *info,
72		     u_int8_t family)
73{
74	return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
75	       &info->repldst_addr, &info->repldst_mask, family);
76}
77
78static inline bool
79ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
80                    const struct nf_conn *ct)
81{
82	const struct nf_conntrack_tuple *tuple;
83
84	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
85	if ((info->match_flags & XT_CONNTRACK_PROTO) &&
86	    (nf_ct_protonum(ct) == info->l4proto) ^
87	    !(info->invert_flags & XT_CONNTRACK_PROTO))
88		return false;
89
90	/* Shortcut to match all recognized protocols by using ->src.all. */
91	if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
92	    (tuple->src.u.all == info->origsrc_port) ^
93	    !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
94		return false;
95
96	if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
97	    (tuple->dst.u.all == info->origdst_port) ^
98	    !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
99		return false;
100
101	tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
102
103	if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
104	    (tuple->src.u.all == info->replsrc_port) ^
105	    !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
106		return false;
107
108	if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
109	    (tuple->dst.u.all == info->repldst_port) ^
110	    !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
111		return false;
112
113	return true;
114}
115
116static inline bool
117port_match(u16 min, u16 max, u16 port, bool invert)
118{
119	return (port >= min && port <= max) ^ invert;
120}
121
122static inline bool
123ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
124		       const struct nf_conn *ct)
125{
126	const struct nf_conntrack_tuple *tuple;
127
128	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
129	if ((info->match_flags & XT_CONNTRACK_PROTO) &&
130	    (nf_ct_protonum(ct) == info->l4proto) ^
131	    !(info->invert_flags & XT_CONNTRACK_PROTO))
132		return false;
133
134	/* Shortcut to match all recognized protocols by using ->src.all. */
135	if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
136	    !port_match(info->origsrc_port, info->origsrc_port_high,
137			ntohs(tuple->src.u.all),
138			info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
139		return false;
140
141	if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
142	    !port_match(info->origdst_port, info->origdst_port_high,
143			ntohs(tuple->dst.u.all),
144			info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
145		return false;
146
147	tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
148
149	if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
150	    !port_match(info->replsrc_port, info->replsrc_port_high,
151			ntohs(tuple->src.u.all),
152			info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
153		return false;
154
155	if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
156	    !port_match(info->repldst_port, info->repldst_port_high,
157			ntohs(tuple->dst.u.all),
158			info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
159		return false;
160
161	return true;
162}
163
164static bool
165conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
166             u16 state_mask, u16 status_mask)
167{
168	const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
169	enum ip_conntrack_info ctinfo;
170	const struct nf_conn *ct;
171	unsigned int statebit;
172
173	ct = nf_ct_get(skb, &ctinfo);
174
175	if (ct) {
176		if (nf_ct_is_untracked(ct))
177			statebit = XT_CONNTRACK_STATE_UNTRACKED;
178		else
179			statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
180	} else
181		statebit = XT_CONNTRACK_STATE_INVALID;
182
183	if (info->match_flags & XT_CONNTRACK_STATE) {
184		if (ct != NULL) {
185			if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
186				statebit |= XT_CONNTRACK_STATE_SNAT;
187			if (test_bit(IPS_DST_NAT_BIT, &ct->status))
188				statebit |= XT_CONNTRACK_STATE_DNAT;
189		}
190		if (!!(state_mask & statebit) ^
191		    !(info->invert_flags & XT_CONNTRACK_STATE))
192			return false;
193	}
194
195	if (ct == NULL)
196		return info->match_flags & XT_CONNTRACK_STATE;
197	if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
198	    (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
199	    !(info->invert_flags & XT_CONNTRACK_DIRECTION))
200		return false;
201
202	if (info->match_flags & XT_CONNTRACK_ORIGSRC)
203		if (conntrack_mt_origsrc(ct, info, par->family) ^
204		    !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
205			return false;
206
207	if (info->match_flags & XT_CONNTRACK_ORIGDST)
208		if (conntrack_mt_origdst(ct, info, par->family) ^
209		    !(info->invert_flags & XT_CONNTRACK_ORIGDST))
210			return false;
211
212	if (info->match_flags & XT_CONNTRACK_REPLSRC)
213		if (conntrack_mt_replsrc(ct, info, par->family) ^
214		    !(info->invert_flags & XT_CONNTRACK_REPLSRC))
215			return false;
216
217	if (info->match_flags & XT_CONNTRACK_REPLDST)
218		if (conntrack_mt_repldst(ct, info, par->family) ^
219		    !(info->invert_flags & XT_CONNTRACK_REPLDST))
220			return false;
221
222	if (par->match->revision != 3) {
223		if (!ct_proto_port_check(info, ct))
224			return false;
225	} else {
226		if (!ct_proto_port_check_v3(par->matchinfo, ct))
227			return false;
228	}
229
230	if ((info->match_flags & XT_CONNTRACK_STATUS) &&
231	    (!!(status_mask & ct->status) ^
232	    !(info->invert_flags & XT_CONNTRACK_STATUS)))
233		return false;
234
235	if (info->match_flags & XT_CONNTRACK_EXPIRES) {
236		unsigned long expires = 0;
237
238		if (timer_pending(&ct->timeout))
239			expires = (ct->timeout.expires - jiffies) / HZ;
240		if ((expires >= info->expires_min &&
241		    expires <= info->expires_max) ^
242		    !(info->invert_flags & XT_CONNTRACK_EXPIRES))
243			return false;
244	}
245	return true;
246}
247
248static bool
249conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
250{
251	const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
252
253	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
254}
255
256static bool
257conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
258{
259	const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
260
261	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
262}
263
264static bool
265conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
266{
267	const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
268
269	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
270}
271
272static int conntrack_mt_check(const struct xt_mtchk_param *par)
273{
274	int ret;
275
276	ret = nf_ct_l3proto_try_module_get(par->family);
277	if (ret < 0)
278		pr_info("cannot load conntrack support for proto=%u\n",
279			par->family);
280	return ret;
281}
282
283static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
284{
285	nf_ct_l3proto_module_put(par->family);
286}
287
288static struct xt_match conntrack_mt_reg[] __read_mostly = {
289	{
290		.name       = "conntrack",
291		.revision   = 1,
292		.family     = NFPROTO_UNSPEC,
293		.matchsize  = sizeof(struct xt_conntrack_mtinfo1),
294		.match      = conntrack_mt_v1,
295		.checkentry = conntrack_mt_check,
296		.destroy    = conntrack_mt_destroy,
297		.me         = THIS_MODULE,
298	},
299	{
300		.name       = "conntrack",
301		.revision   = 2,
302		.family     = NFPROTO_UNSPEC,
303		.matchsize  = sizeof(struct xt_conntrack_mtinfo2),
304		.match      = conntrack_mt_v2,
305		.checkentry = conntrack_mt_check,
306		.destroy    = conntrack_mt_destroy,
307		.me         = THIS_MODULE,
308	},
309	{
310		.name       = "conntrack",
311		.revision   = 3,
312		.family     = NFPROTO_UNSPEC,
313		.matchsize  = sizeof(struct xt_conntrack_mtinfo3),
314		.match      = conntrack_mt_v3,
315		.checkentry = conntrack_mt_check,
316		.destroy    = conntrack_mt_destroy,
317		.me         = THIS_MODULE,
318	},
319};
320
321static int __init conntrack_mt_init(void)
322{
323	return xt_register_matches(conntrack_mt_reg,
324	       ARRAY_SIZE(conntrack_mt_reg));
325}
326
327static void __exit conntrack_mt_exit(void)
328{
329	xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
330}
331
332module_init(conntrack_mt_init);
333module_exit(conntrack_mt_exit);
334