1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * xt_conntrack - Netfilter module to match connection tracking
4 * information. (Superset of Rusty's minimalistic state match.)
5 *
6 * (C) 2001 Marc Boucher (marc@mbsi.ca).
7 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
8 * Copyright © CC Computer Consultants GmbH, 2007 - 2008
9 */
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 #include <linux/module.h>
12 #include <linux/skbuff.h>
13 #include <net/ipv6.h>
14 #include <linux/netfilter/x_tables.h>
15 #include <linux/netfilter/xt_conntrack.h>
16 #include <net/netfilter/nf_conntrack.h>
17
18 MODULE_LICENSE("GPL");
19 MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
20 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
21 MODULE_DESCRIPTION("Xtables: connection tracking state match");
22 MODULE_ALIAS("ipt_conntrack");
23 MODULE_ALIAS("ip6t_conntrack");
24
25 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)26 conntrack_addrcmp(const union nf_inet_addr *kaddr,
27 const union nf_inet_addr *uaddr,
28 const union nf_inet_addr *umask, unsigned int l3proto)
29 {
30 if (l3proto == NFPROTO_IPV4)
31 return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
32 else if (l3proto == NFPROTO_IPV6)
33 return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
34 &uaddr->in6) == 0;
35 else
36 return false;
37 }
38
39 static inline bool
conntrack_mt_origsrc(const struct nf_conn * ct,const struct xt_conntrack_mtinfo2 * info,u_int8_t family)40 conntrack_mt_origsrc(const struct nf_conn *ct,
41 const struct xt_conntrack_mtinfo2 *info,
42 u_int8_t family)
43 {
44 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
45 &info->origsrc_addr, &info->origsrc_mask, family);
46 }
47
48 static inline bool
conntrack_mt_origdst(const struct nf_conn * ct,const struct xt_conntrack_mtinfo2 * info,u_int8_t family)49 conntrack_mt_origdst(const struct nf_conn *ct,
50 const struct xt_conntrack_mtinfo2 *info,
51 u_int8_t family)
52 {
53 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
54 &info->origdst_addr, &info->origdst_mask, family);
55 }
56
57 static inline bool
conntrack_mt_replsrc(const struct nf_conn * ct,const struct xt_conntrack_mtinfo2 * info,u_int8_t family)58 conntrack_mt_replsrc(const struct nf_conn *ct,
59 const struct xt_conntrack_mtinfo2 *info,
60 u_int8_t family)
61 {
62 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
63 &info->replsrc_addr, &info->replsrc_mask, family);
64 }
65
66 static inline bool
conntrack_mt_repldst(const struct nf_conn * ct,const struct xt_conntrack_mtinfo2 * info,u_int8_t family)67 conntrack_mt_repldst(const struct nf_conn *ct,
68 const struct xt_conntrack_mtinfo2 *info,
69 u_int8_t family)
70 {
71 return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
72 &info->repldst_addr, &info->repldst_mask, family);
73 }
74
75 static inline bool
ct_proto_port_check(const struct xt_conntrack_mtinfo2 * info,const struct nf_conn * ct)76 ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
77 const struct nf_conn *ct)
78 {
79 const struct nf_conntrack_tuple *tuple;
80
81 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
82 if ((info->match_flags & XT_CONNTRACK_PROTO) &&
83 (nf_ct_protonum(ct) == info->l4proto) ^
84 !(info->invert_flags & XT_CONNTRACK_PROTO))
85 return false;
86
87 /* Shortcut to match all recognized protocols by using ->src.all. */
88 if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
89 (tuple->src.u.all == info->origsrc_port) ^
90 !(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
91 return false;
92
93 if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
94 (tuple->dst.u.all == info->origdst_port) ^
95 !(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
96 return false;
97
98 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
99
100 if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
101 (tuple->src.u.all == info->replsrc_port) ^
102 !(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
103 return false;
104
105 if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
106 (tuple->dst.u.all == info->repldst_port) ^
107 !(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
108 return false;
109
110 return true;
111 }
112
113 static inline bool
port_match(u16 min,u16 max,u16 port,bool invert)114 port_match(u16 min, u16 max, u16 port, bool invert)
115 {
116 return (port >= min && port <= max) ^ invert;
117 }
118
119 static inline bool
ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 * info,const struct nf_conn * ct)120 ct_proto_port_check_v3(const struct xt_conntrack_mtinfo3 *info,
121 const struct nf_conn *ct)
122 {
123 const struct nf_conntrack_tuple *tuple;
124
125 tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
126 if ((info->match_flags & XT_CONNTRACK_PROTO) &&
127 (nf_ct_protonum(ct) == info->l4proto) ^
128 !(info->invert_flags & XT_CONNTRACK_PROTO))
129 return false;
130
131 /* Shortcut to match all recognized protocols by using ->src.all. */
132 if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
133 !port_match(info->origsrc_port, info->origsrc_port_high,
134 ntohs(tuple->src.u.all),
135 info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
136 return false;
137
138 if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
139 !port_match(info->origdst_port, info->origdst_port_high,
140 ntohs(tuple->dst.u.all),
141 info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
142 return false;
143
144 tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
145
146 if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
147 !port_match(info->replsrc_port, info->replsrc_port_high,
148 ntohs(tuple->src.u.all),
149 info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
150 return false;
151
152 if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
153 !port_match(info->repldst_port, info->repldst_port_high,
154 ntohs(tuple->dst.u.all),
155 info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
156 return false;
157
158 return true;
159 }
160
161 static bool
conntrack_mt(const struct sk_buff * skb,struct xt_action_param * par,u16 state_mask,u16 status_mask)162 conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
163 u16 state_mask, u16 status_mask)
164 {
165 const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
166 enum ip_conntrack_info ctinfo;
167 const struct nf_conn *ct;
168 unsigned int statebit;
169
170 ct = nf_ct_get(skb, &ctinfo);
171
172 if (ct)
173 statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
174 else if (ctinfo == IP_CT_UNTRACKED)
175 statebit = XT_CONNTRACK_STATE_UNTRACKED;
176 else
177 statebit = XT_CONNTRACK_STATE_INVALID;
178
179 if (info->match_flags & XT_CONNTRACK_STATE) {
180 if (ct != NULL) {
181 if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
182 statebit |= XT_CONNTRACK_STATE_SNAT;
183 if (test_bit(IPS_DST_NAT_BIT, &ct->status))
184 statebit |= XT_CONNTRACK_STATE_DNAT;
185 }
186 if (!!(state_mask & statebit) ^
187 !(info->invert_flags & XT_CONNTRACK_STATE))
188 return false;
189 }
190
191 if (ct == NULL)
192 return info->match_flags & XT_CONNTRACK_STATE;
193 if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
194 (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
195 !(info->invert_flags & XT_CONNTRACK_DIRECTION))
196 return false;
197
198 if (info->match_flags & XT_CONNTRACK_ORIGSRC)
199 if (conntrack_mt_origsrc(ct, info, xt_family(par)) ^
200 !(info->invert_flags & XT_CONNTRACK_ORIGSRC))
201 return false;
202
203 if (info->match_flags & XT_CONNTRACK_ORIGDST)
204 if (conntrack_mt_origdst(ct, info, xt_family(par)) ^
205 !(info->invert_flags & XT_CONNTRACK_ORIGDST))
206 return false;
207
208 if (info->match_flags & XT_CONNTRACK_REPLSRC)
209 if (conntrack_mt_replsrc(ct, info, xt_family(par)) ^
210 !(info->invert_flags & XT_CONNTRACK_REPLSRC))
211 return false;
212
213 if (info->match_flags & XT_CONNTRACK_REPLDST)
214 if (conntrack_mt_repldst(ct, info, xt_family(par)) ^
215 !(info->invert_flags & XT_CONNTRACK_REPLDST))
216 return false;
217
218 if (par->match->revision != 3) {
219 if (!ct_proto_port_check(info, ct))
220 return false;
221 } else {
222 if (!ct_proto_port_check_v3(par->matchinfo, ct))
223 return false;
224 }
225
226 if ((info->match_flags & XT_CONNTRACK_STATUS) &&
227 (!!(status_mask & ct->status) ^
228 !(info->invert_flags & XT_CONNTRACK_STATUS)))
229 return false;
230
231 if (info->match_flags & XT_CONNTRACK_EXPIRES) {
232 unsigned long expires = nf_ct_expires(ct) / HZ;
233
234 if ((expires >= info->expires_min &&
235 expires <= info->expires_max) ^
236 !(info->invert_flags & XT_CONNTRACK_EXPIRES))
237 return false;
238 }
239 return true;
240 }
241
242 static bool
conntrack_mt_v1(const struct sk_buff * skb,struct xt_action_param * par)243 conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
244 {
245 const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
246
247 return conntrack_mt(skb, par, info->state_mask, info->status_mask);
248 }
249
250 static bool
conntrack_mt_v2(const struct sk_buff * skb,struct xt_action_param * par)251 conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
252 {
253 const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
254
255 return conntrack_mt(skb, par, info->state_mask, info->status_mask);
256 }
257
258 static bool
conntrack_mt_v3(const struct sk_buff * skb,struct xt_action_param * par)259 conntrack_mt_v3(const struct sk_buff *skb, struct xt_action_param *par)
260 {
261 const struct xt_conntrack_mtinfo3 *info = par->matchinfo;
262
263 return conntrack_mt(skb, par, info->state_mask, info->status_mask);
264 }
265
conntrack_mt_check(const struct xt_mtchk_param * par)266 static int conntrack_mt_check(const struct xt_mtchk_param *par)
267 {
268 int ret;
269
270 ret = nf_ct_netns_get(par->net, par->family);
271 if (ret < 0)
272 pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
273 par->family);
274 return ret;
275 }
276
conntrack_mt_destroy(const struct xt_mtdtor_param * par)277 static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
278 {
279 nf_ct_netns_put(par->net, par->family);
280 }
281
282 static struct xt_match conntrack_mt_reg[] __read_mostly = {
283 {
284 .name = "conntrack",
285 .revision = 1,
286 .family = NFPROTO_UNSPEC,
287 .matchsize = sizeof(struct xt_conntrack_mtinfo1),
288 .match = conntrack_mt_v1,
289 .checkentry = conntrack_mt_check,
290 .destroy = conntrack_mt_destroy,
291 .me = THIS_MODULE,
292 },
293 {
294 .name = "conntrack",
295 .revision = 2,
296 .family = NFPROTO_UNSPEC,
297 .matchsize = sizeof(struct xt_conntrack_mtinfo2),
298 .match = conntrack_mt_v2,
299 .checkentry = conntrack_mt_check,
300 .destroy = conntrack_mt_destroy,
301 .me = THIS_MODULE,
302 },
303 {
304 .name = "conntrack",
305 .revision = 3,
306 .family = NFPROTO_UNSPEC,
307 .matchsize = sizeof(struct xt_conntrack_mtinfo3),
308 .match = conntrack_mt_v3,
309 .checkentry = conntrack_mt_check,
310 .destroy = conntrack_mt_destroy,
311 .me = THIS_MODULE,
312 },
313 };
314
conntrack_mt_init(void)315 static int __init conntrack_mt_init(void)
316 {
317 return xt_register_matches(conntrack_mt_reg,
318 ARRAY_SIZE(conntrack_mt_reg));
319 }
320
conntrack_mt_exit(void)321 static void __exit conntrack_mt_exit(void)
322 {
323 xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
324 }
325
326 module_init(conntrack_mt_init);
327 module_exit(conntrack_mt_exit);
328