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
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@computergmbh.de>");
23 MODULE_DESCRIPTION("Xtables: connection tracking state match");
24 MODULE_ALIAS("ipt_conntrack");
25 MODULE_ALIAS("ip6t_conntrack");
26
27 static bool
conntrack_mt_v0(const struct sk_buff * skb,const struct xt_match_param * par)28 conntrack_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
29 {
30 const struct xt_conntrack_info *sinfo = par->matchinfo;
31 const struct nf_conn *ct;
32 enum ip_conntrack_info ctinfo;
33 unsigned int statebit;
34
35 ct = nf_ct_get(skb, &ctinfo);
36
37 #define FWINV(bool, invflg) ((bool) ^ !!(sinfo->invflags & (invflg)))
38
39 if (ct == &nf_conntrack_untracked)
40 statebit = XT_CONNTRACK_STATE_UNTRACKED;
41 else if (ct)
42 statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
43 else
44 statebit = XT_CONNTRACK_STATE_INVALID;
45
46 if (sinfo->flags & XT_CONNTRACK_STATE) {
47 if (ct) {
48 if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
49 statebit |= XT_CONNTRACK_STATE_SNAT;
50 if (test_bit(IPS_DST_NAT_BIT, &ct->status))
51 statebit |= XT_CONNTRACK_STATE_DNAT;
52 }
53 if (FWINV((statebit & sinfo->statemask) == 0,
54 XT_CONNTRACK_STATE))
55 return false;
56 }
57
58 if (ct == NULL) {
59 if (sinfo->flags & ~XT_CONNTRACK_STATE)
60 return false;
61 return true;
62 }
63
64 if (sinfo->flags & XT_CONNTRACK_PROTO &&
65 FWINV(nf_ct_protonum(ct) !=
66 sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum,
67 XT_CONNTRACK_PROTO))
68 return false;
69
70 if (sinfo->flags & XT_CONNTRACK_ORIGSRC &&
71 FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip &
72 sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) !=
73 sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip,
74 XT_CONNTRACK_ORIGSRC))
75 return false;
76
77 if (sinfo->flags & XT_CONNTRACK_ORIGDST &&
78 FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip &
79 sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) !=
80 sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip,
81 XT_CONNTRACK_ORIGDST))
82 return false;
83
84 if (sinfo->flags & XT_CONNTRACK_REPLSRC &&
85 FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip &
86 sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) !=
87 sinfo->tuple[IP_CT_DIR_REPLY].src.ip,
88 XT_CONNTRACK_REPLSRC))
89 return false;
90
91 if (sinfo->flags & XT_CONNTRACK_REPLDST &&
92 FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip &
93 sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) !=
94 sinfo->tuple[IP_CT_DIR_REPLY].dst.ip,
95 XT_CONNTRACK_REPLDST))
96 return false;
97
98 if (sinfo->flags & XT_CONNTRACK_STATUS &&
99 FWINV((ct->status & sinfo->statusmask) == 0,
100 XT_CONNTRACK_STATUS))
101 return false;
102
103 if(sinfo->flags & XT_CONNTRACK_EXPIRES) {
104 unsigned long expires = timer_pending(&ct->timeout) ?
105 (ct->timeout.expires - jiffies)/HZ : 0;
106
107 if (FWINV(!(expires >= sinfo->expires_min &&
108 expires <= sinfo->expires_max),
109 XT_CONNTRACK_EXPIRES))
110 return false;
111 }
112 return true;
113 #undef FWINV
114 }
115
116 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)117 conntrack_addrcmp(const union nf_inet_addr *kaddr,
118 const union nf_inet_addr *uaddr,
119 const union nf_inet_addr *umask, unsigned int l3proto)
120 {
121 if (l3proto == NFPROTO_IPV4)
122 return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
123 else if (l3proto == NFPROTO_IPV6)
124 return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
125 &uaddr->in6) == 0;
126 else
127 return false;
128 }
129
130 static inline bool
conntrack_mt_origsrc(const struct nf_conn * ct,const struct xt_conntrack_mtinfo1 * info,u_int8_t family)131 conntrack_mt_origsrc(const struct nf_conn *ct,
132 const struct xt_conntrack_mtinfo1 *info,
133 u_int8_t family)
134 {
135 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
136 &info->origsrc_addr, &info->origsrc_mask, family);
137 }
138
139 static inline bool
conntrack_mt_origdst(const struct nf_conn * ct,const struct xt_conntrack_mtinfo1 * info,u_int8_t family)140 conntrack_mt_origdst(const struct nf_conn *ct,
141 const struct xt_conntrack_mtinfo1 *info,
142 u_int8_t family)
143 {
144 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
145 &info->origdst_addr, &info->origdst_mask, family);
146 }
147
148 static inline bool
conntrack_mt_replsrc(const struct nf_conn * ct,const struct xt_conntrack_mtinfo1 * info,u_int8_t family)149 conntrack_mt_replsrc(const struct nf_conn *ct,
150 const struct xt_conntrack_mtinfo1 *info,
151 u_int8_t family)
152 {
153 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
154 &info->replsrc_addr, &info->replsrc_mask, family);
155 }
156
157 static inline bool
conntrack_mt_repldst(const struct nf_conn * ct,const struct xt_conntrack_mtinfo1 * info,u_int8_t family)158 conntrack_mt_repldst(const struct nf_conn *ct,
159 const struct xt_conntrack_mtinfo1 *info,
160 u_int8_t family)
161 {
162 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
163 &info->repldst_addr, &info->repldst_mask, family);
164 }
165
166 static inline bool
ct_proto_port_check(const struct xt_conntrack_mtinfo1 * info,const struct nf_conn * ct)167 ct_proto_port_check(const struct xt_conntrack_mtinfo1 *info,
168 const struct nf_conn *ct)
169 {
170 const struct nf_conntrack_tuple *tuple;
171
172 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
173 if ((info->match_flags & XT_CONNTRACK_PROTO) &&
174 (nf_ct_protonum(ct) == info->l4proto) ^
175 !(info->invert_flags & XT_CONNTRACK_PROTO))
176 return false;
177
178 /* Shortcut to match all recognized protocols by using ->src.all. */
179 if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
180 (tuple->src.u.all == info->origsrc_port) ^
181 !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
182 return false;
183
184 if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
185 (tuple->dst.u.all == info->origdst_port) ^
186 !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
187 return false;
188
189 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
190
191 if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
192 (tuple->src.u.all == info->replsrc_port) ^
193 !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
194 return false;
195
196 if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
197 (tuple->dst.u.all == info->repldst_port) ^
198 !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
199 return false;
200
201 return true;
202 }
203
204 static bool
conntrack_mt(const struct sk_buff * skb,const struct xt_match_param * par)205 conntrack_mt(const struct sk_buff *skb, const struct xt_match_param *par)
206 {
207 const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
208 enum ip_conntrack_info ctinfo;
209 const struct nf_conn *ct;
210 unsigned int statebit;
211
212 ct = nf_ct_get(skb, &ctinfo);
213
214 if (ct == &nf_conntrack_untracked)
215 statebit = XT_CONNTRACK_STATE_UNTRACKED;
216 else if (ct != NULL)
217 statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
218 else
219 statebit = XT_CONNTRACK_STATE_INVALID;
220
221 if (info->match_flags & XT_CONNTRACK_STATE) {
222 if (ct != NULL) {
223 if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
224 statebit |= XT_CONNTRACK_STATE_SNAT;
225 if (test_bit(IPS_DST_NAT_BIT, &ct->status))
226 statebit |= XT_CONNTRACK_STATE_DNAT;
227 }
228 if (!!(info->state_mask & statebit) ^
229 !(info->invert_flags & XT_CONNTRACK_STATE))
230 return false;
231 }
232
233 if (ct == NULL)
234 return info->match_flags & XT_CONNTRACK_STATE;
235 if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
236 (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
237 !!(info->invert_flags & XT_CONNTRACK_DIRECTION))
238 return false;
239
240 if (info->match_flags & XT_CONNTRACK_ORIGSRC)
241 if (conntrack_mt_origsrc(ct, info, par->family) ^
242 !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
243 return false;
244
245 if (info->match_flags & XT_CONNTRACK_ORIGDST)
246 if (conntrack_mt_origdst(ct, info, par->family) ^
247 !(info->invert_flags & XT_CONNTRACK_ORIGDST))
248 return false;
249
250 if (info->match_flags & XT_CONNTRACK_REPLSRC)
251 if (conntrack_mt_replsrc(ct, info, par->family) ^
252 !(info->invert_flags & XT_CONNTRACK_REPLSRC))
253 return false;
254
255 if (info->match_flags & XT_CONNTRACK_REPLDST)
256 if (conntrack_mt_repldst(ct, info, par->family) ^
257 !(info->invert_flags & XT_CONNTRACK_REPLDST))
258 return false;
259
260 if (!ct_proto_port_check(info, ct))
261 return false;
262
263 if ((info->match_flags & XT_CONNTRACK_STATUS) &&
264 (!!(info->status_mask & ct->status) ^
265 !(info->invert_flags & XT_CONNTRACK_STATUS)))
266 return false;
267
268 if (info->match_flags & XT_CONNTRACK_EXPIRES) {
269 unsigned long expires = 0;
270
271 if (timer_pending(&ct->timeout))
272 expires = (ct->timeout.expires - jiffies) / HZ;
273 if ((expires >= info->expires_min &&
274 expires <= info->expires_max) ^
275 !(info->invert_flags & XT_CONNTRACK_EXPIRES))
276 return false;
277 }
278 return true;
279 }
280
conntrack_mt_check(const struct xt_mtchk_param * par)281 static bool conntrack_mt_check(const struct xt_mtchk_param *par)
282 {
283 if (nf_ct_l3proto_try_module_get(par->family) < 0) {
284 printk(KERN_WARNING "can't load conntrack support for "
285 "proto=%u\n", par->family);
286 return false;
287 }
288 return true;
289 }
290
conntrack_mt_destroy(const struct xt_mtdtor_param * par)291 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
292 {
293 nf_ct_l3proto_module_put(par->family);
294 }
295
296 #ifdef CONFIG_COMPAT
297 struct compat_xt_conntrack_info
298 {
299 compat_uint_t statemask;
300 compat_uint_t statusmask;
301 struct ip_conntrack_old_tuple tuple[IP_CT_DIR_MAX];
302 struct in_addr sipmsk[IP_CT_DIR_MAX];
303 struct in_addr dipmsk[IP_CT_DIR_MAX];
304 compat_ulong_t expires_min;
305 compat_ulong_t expires_max;
306 u_int8_t flags;
307 u_int8_t invflags;
308 };
309
conntrack_mt_compat_from_user_v0(void * dst,void * src)310 static void conntrack_mt_compat_from_user_v0(void *dst, void *src)
311 {
312 const struct compat_xt_conntrack_info *cm = src;
313 struct xt_conntrack_info m = {
314 .statemask = cm->statemask,
315 .statusmask = cm->statusmask,
316 .expires_min = cm->expires_min,
317 .expires_max = cm->expires_max,
318 .flags = cm->flags,
319 .invflags = cm->invflags,
320 };
321 memcpy(m.tuple, cm->tuple, sizeof(m.tuple));
322 memcpy(m.sipmsk, cm->sipmsk, sizeof(m.sipmsk));
323 memcpy(m.dipmsk, cm->dipmsk, sizeof(m.dipmsk));
324 memcpy(dst, &m, sizeof(m));
325 }
326
conntrack_mt_compat_to_user_v0(void __user * dst,void * src)327 static int conntrack_mt_compat_to_user_v0(void __user *dst, void *src)
328 {
329 const struct xt_conntrack_info *m = src;
330 struct compat_xt_conntrack_info cm = {
331 .statemask = m->statemask,
332 .statusmask = m->statusmask,
333 .expires_min = m->expires_min,
334 .expires_max = m->expires_max,
335 .flags = m->flags,
336 .invflags = m->invflags,
337 };
338 memcpy(cm.tuple, m->tuple, sizeof(cm.tuple));
339 memcpy(cm.sipmsk, m->sipmsk, sizeof(cm.sipmsk));
340 memcpy(cm.dipmsk, m->dipmsk, sizeof(cm.dipmsk));
341 return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
342 }
343 #endif
344
345 static struct xt_match conntrack_mt_reg[] __read_mostly = {
346 {
347 .name = "conntrack",
348 .revision = 0,
349 .family = NFPROTO_IPV4,
350 .match = conntrack_mt_v0,
351 .checkentry = conntrack_mt_check,
352 .destroy = conntrack_mt_destroy,
353 .matchsize = sizeof(struct xt_conntrack_info),
354 .me = THIS_MODULE,
355 #ifdef CONFIG_COMPAT
356 .compatsize = sizeof(struct compat_xt_conntrack_info),
357 .compat_from_user = conntrack_mt_compat_from_user_v0,
358 .compat_to_user = conntrack_mt_compat_to_user_v0,
359 #endif
360 },
361 {
362 .name = "conntrack",
363 .revision = 1,
364 .family = NFPROTO_UNSPEC,
365 .matchsize = sizeof(struct xt_conntrack_mtinfo1),
366 .match = conntrack_mt,
367 .checkentry = conntrack_mt_check,
368 .destroy = conntrack_mt_destroy,
369 .me = THIS_MODULE,
370 },
371 };
372
conntrack_mt_init(void)373 static int __init conntrack_mt_init(void)
374 {
375 return xt_register_matches(conntrack_mt_reg,
376 ARRAY_SIZE(conntrack_mt_reg));
377 }
378
conntrack_mt_exit(void)379 static void __exit conntrack_mt_exit(void)
380 {
381 xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
382 }
383
384 module_init(conntrack_mt_init);
385 module_exit(conntrack_mt_exit);
386