xref: /openbmc/linux/net/netfilter/xt_conntrack.c (revision fca3aa16) 
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 
21 MODULE_LICENSE("GPL");
22 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
23 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
24 MODULE_DESCRIPTION("Xtables: connection tracking state match");
25 MODULE_ALIAS("ipt_conntrack");
26 MODULE_ALIAS("ip6t_conntrack");
27 
28 static bool
29 conntrack_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 
42 static inline bool
43 conntrack_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 
51 static inline bool
52 conntrack_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 
60 static inline bool
61 conntrack_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 
69 static inline bool
70 conntrack_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 
78 static inline bool
79 ct_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 
116 static inline bool
117 port_match(u16 min, u16 max, u16 port, bool invert)
118 {
119 	return (port >= min && port <= max) ^ invert;
120 }
121 
122 static inline bool
123 ct_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 
164 static bool
165 conntrack_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 		statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
177 	else if (ctinfo == IP_CT_UNTRACKED)
178 		statebit = XT_CONNTRACK_STATE_UNTRACKED;
179 	else
180 		statebit = XT_CONNTRACK_STATE_INVALID;
181 
182 	if (info->match_flags & XT_CONNTRACK_STATE) {
183 		if (ct != NULL) {
184 			if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
185 				statebit |= XT_CONNTRACK_STATE_SNAT;
186 			if (test_bit(IPS_DST_NAT_BIT, &ct->status))
187 				statebit |= XT_CONNTRACK_STATE_DNAT;
188 		}
189 		if (!!(state_mask & statebit) ^
190 		    !(info->invert_flags & XT_CONNTRACK_STATE))
191 			return false;
192 	}
193 
194 	if (ct == NULL)
195 		return info->match_flags & XT_CONNTRACK_STATE;
196 	if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
197 	    (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
198 	    !(info->invert_flags & XT_CONNTRACK_DIRECTION))
199 		return false;
200 
201 	if (info->match_flags & XT_CONNTRACK_ORIGSRC)
202 		if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
203 		    !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
204 			return false;
205 
206 	if (info->match_flags & XT_CONNTRACK_ORIGDST)
207 		if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
208 		    !(info->invert_flags & XT_CONNTRACK_ORIGDST))
209 			return false;
210 
211 	if (info->match_flags & XT_CONNTRACK_REPLSRC)
212 		if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
213 		    !(info->invert_flags & XT_CONNTRACK_REPLSRC))
214 			return false;
215 
216 	if (info->match_flags & XT_CONNTRACK_REPLDST)
217 		if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
218 		    !(info->invert_flags & XT_CONNTRACK_REPLDST))
219 			return false;
220 
221 	if (par->match->revision != 3) {
222 		if (!ct_proto_port_check(info, ct))
223 			return false;
224 	} else {
225 		if (!ct_proto_port_check_v3(par->matchinfo, ct))
226 			return false;
227 	}
228 
229 	if ((info->match_flags & XT_CONNTRACK_STATUS) &&
230 	    (!!(status_mask & ct->status) ^
231 	    !(info->invert_flags & XT_CONNTRACK_STATUS)))
232 		return false;
233 
234 	if (info->match_flags & XT_CONNTRACK_EXPIRES) {
235 		unsigned long expires = nf_ct_expires(ct) / HZ;
236 
237 		if ((expires >= info->expires_min &&
238 		    expires <= info->expires_max) ^
239 		    !(info->invert_flags & XT_CONNTRACK_EXPIRES))
240 			return false;
241 	}
242 	return true;
243 }
244 
245 static bool
246 conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
247 {
248 	const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
249 
250 	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
251 }
252 
253 static bool
254 conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
255 {
256 	const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
257 
258 	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
259 }
260 
261 static bool
262 conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
263 {
264 	const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
265 
266 	return conntrack_mt(skb, par, info->state_mask, info->status_mask);
267 }
268 
269 static int conntrack_mt_check(const struct xt_mtchk_param *par)
270 {
271 	int ret;
272 
273 	ret = nf_ct_netns_get(par->net, par->family);
274 	if (ret < 0)
275 		pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
276 				    par->family);
277 	return ret;
278 }
279 
280 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
281 {
282 	nf_ct_netns_put(par->net, par->family);
283 }
284 
285 static struct xt_match conntrack_mt_reg[] __read_mostly = {
286 	{
287 		.name       = "conntrack",
288 		.revision   = 1,
289 		.family     = NFPROTO_UNSPEC,
290 		.matchsize  = sizeof(struct xt_conntrack_mtinfo1),
291 		.match      = conntrack_mt_v1,
292 		.checkentry = conntrack_mt_check,
293 		.destroy    = conntrack_mt_destroy,
294 		.me         = THIS_MODULE,
295 	},
296 	{
297 		.name       = "conntrack",
298 		.revision   = 2,
299 		.family     = NFPROTO_UNSPEC,
300 		.matchsize  = sizeof(struct xt_conntrack_mtinfo2),
301 		.match      = conntrack_mt_v2,
302 		.checkentry = conntrack_mt_check,
303 		.destroy    = conntrack_mt_destroy,
304 		.me         = THIS_MODULE,
305 	},
306 	{
307 		.name       = "conntrack",
308 		.revision   = 3,
309 		.family     = NFPROTO_UNSPEC,
310 		.matchsize  = sizeof(struct xt_conntrack_mtinfo3),
311 		.match      = conntrack_mt_v3,
312 		.checkentry = conntrack_mt_check,
313 		.destroy    = conntrack_mt_destroy,
314 		.me         = THIS_MODULE,
315 	},
316 };
317 
318 static int __init conntrack_mt_init(void)
319 {
320 	return xt_register_matches(conntrack_mt_reg,
321 	       ARRAY_SIZE(conntrack_mt_reg));
322 }
323 
324 static void __exit conntrack_mt_exit(void)
325 {
326 	xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
327 }
328 
329 module_init(conntrack_mt_init);
330 module_exit(conntrack_mt_exit);
331