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
|
/*
* xt_conntrack - Netfilter module to match connection tracking
* information. (Superset of Rusty's minimalistic state match.)
*
* (C) 2001 Marc Boucher (marc@mbsi.ca).
* (C) 2006-2012 Patrick McHardy <kaber@trash.net>
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
*
* 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/skbuff.h>
#include <net/ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_conntrack.h>
#include <net/netfilter/nf_conntrack.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: connection tracking state match");
MODULE_ALIAS("ipt_conntrack");
MODULE_ALIAS("ip6t_conntrack");
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)
{
if (l3proto == NFPROTO_IPV4)
return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
else if (l3proto == NFPROTO_IPV6)
return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
&uaddr->in6) == 0;
else
return false;
}
static inline bool
conntrack_mt_origsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
&info->origsrc_addr, &info->origsrc_mask, family);
}
static inline bool
conntrack_mt_origdst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
&info->origdst_addr, &info->origdst_mask, family);
}
static inline bool
conntrack_mt_replsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
&info->replsrc_addr, &info->replsrc_mask, family);
}
static inline bool
conntrack_mt_repldst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
&info->repldst_addr, &info->repldst_mask, family);
}
static inline bool
ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
const struct nf_conn *ct)
{
const struct nf_conntrack_tuple *tuple;
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
if ((info->match_flags & XT_CONNTRACK_PROTO) &&
(nf_ct_protonum(ct) == info->l4proto) ^
!(info->invert_flags & XT_CONNTRACK_PROTO))
return false;
/* Shortcut to match all recognized protocols by using ->src.all. */
if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
(tuple->src.u.all == info->origsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
(tuple->dst.u.all == info->origdst_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
return false;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
(tuple->src.u.all == info->replsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
(tuple->dst.u.all == info->repldst_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
return false;
return true;
}
static inline bool
port_match(u16 min, u16 max, u16 port, bool invert)
{
return (port >= min && port <= max) ^ invert;
}
static inline bool
ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
const struct nf_conn *ct)
{
const struct nf_conntrack_tuple *tuple;
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
if ((info->match_flags & XT_CONNTRACK_PROTO) &&
(nf_ct_protonum(ct) == info->l4proto) ^
!(info->invert_flags & XT_CONNTRACK_PROTO))
return false;
/* Shortcut to match all recognized protocols by using ->src.all. */
if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
!port_match(info->origsrc_port, info->origsrc_port_high,
ntohs(tuple->src.u.all),
info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
!port_match(info->origdst_port, info->origdst_port_high,
ntohs(tuple->dst.u.all),
info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
return false;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
!port_match(info->replsrc_port, info->replsrc_port_high,
ntohs(tuple->src.u.all),
info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
!port_match(info->repldst_port, info->repldst_port_high,
ntohs(tuple->dst.u.all),
info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
return false;
return true;
}
static bool
conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
u16 state_mask, u16 status_mask)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
enum ip_conntrack_info ctinfo;
const struct nf_conn *ct;
unsigned int statebit;
ct = nf_ct_get(skb, &ctinfo);
if (ct)
statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
else if (ctinfo == IP_CT_UNTRACKED)
statebit = XT_CONNTRACK_STATE_UNTRACKED;
else
statebit = XT_CONNTRACK_STATE_INVALID;
if (info->match_flags & XT_CONNTRACK_STATE) {
if (ct != NULL) {
if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_SNAT;
if (test_bit(IPS_DST_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_DNAT;
}
if (!!(state_mask & statebit) ^
!(info->invert_flags & XT_CONNTRACK_STATE))
return false;
}
if (ct == NULL)
return info->match_flags & XT_CONNTRACK_STATE;
if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
(CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
!(info->invert_flags & XT_CONNTRACK_DIRECTION))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGSRC)
if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGDST)
if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST))
return false;
if (info->match_flags & XT_CONNTRACK_REPLSRC)
if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC))
return false;
if (info->match_flags & XT_CONNTRACK_REPLDST)
if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST))
return false;
if (par->match->revision != 3) {
if (!ct_proto_port_check(info, ct))
return false;
} else {
if (!ct_proto_port_check_v3(par->matchinfo, ct))
return false;
}
if ((info->match_flags & XT_CONNTRACK_STATUS) &&
(!!(status_mask & ct->status) ^
!(info->invert_flags & XT_CONNTRACK_STATUS)))
return false;
if (info->match_flags & XT_CONNTRACK_EXPIRES) {
unsigned long expires = nf_ct_expires(ct) / HZ;
if ((expires >= info->expires_min &&
expires <= info->expires_max) ^
!(info->invert_flags & XT_CONNTRACK_EXPIRES))
return false;
}
return true;
}
static bool
conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static bool
conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static bool
conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static int conntrack_mt_check(const struct xt_mtchk_param *par)
{
int ret;
ret = nf_ct_netns_get(par->net, par->family);
if (ret < 0)
pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
par->family);
return ret;
}
static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
{
nf_ct_netns_put(par->net, par->family);
}
static struct xt_match conntrack_mt_reg[] __read_mostly = {
{
.name = "conntrack",
.revision = 1,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo1),
.match = conntrack_mt_v1,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
{
.name = "conntrack",
.revision = 2,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo2),
.match = conntrack_mt_v2,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
{
.name = "conntrack",
.revision = 3,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo3),
.match = conntrack_mt_v3,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
};
static int __init conntrack_mt_init(void)
{
return xt_register_matches(conntrack_mt_reg,
ARRAY_SIZE(conntrack_mt_reg));
}
static void __exit conntrack_mt_exit(void)
{
xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
}
module_init(conntrack_mt_init);
module_exit(conntrack_mt_exit);
|
