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