1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
4 */
5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
6 #include <linux/module.h>
7 #include <linux/gfp.h>
8 #include <linux/skbuff.h>
9 #include <linux/netfilter_ipv4/ip_tables.h>
10 #include <linux/netfilter_ipv6/ip6_tables.h>
11 #include <linux/netfilter/x_tables.h>
12 #include <linux/netfilter/xt_CT.h>
13 #include <net/netfilter/nf_conntrack.h>
14 #include <net/netfilter/nf_conntrack_l4proto.h>
15 #include <net/netfilter/nf_conntrack_helper.h>
16 #include <net/netfilter/nf_conntrack_ecache.h>
17 #include <net/netfilter/nf_conntrack_timeout.h>
18 #include <net/netfilter/nf_conntrack_zones.h>
19
xt_ct_target(struct sk_buff * skb,struct nf_conn * ct)20 static inline int xt_ct_target(struct sk_buff *skb, struct nf_conn *ct)
21 {
22 /* Previously seen (loopback)? Ignore. */
23 if (skb->_nfct != 0)
24 return XT_CONTINUE;
25
26 if (ct) {
27 atomic_inc(&ct->ct_general.use);
28 nf_ct_set(skb, ct, IP_CT_NEW);
29 } else {
30 nf_ct_set(skb, ct, IP_CT_UNTRACKED);
31 }
32
33 return XT_CONTINUE;
34 }
35
xt_ct_target_v0(struct sk_buff * skb,const struct xt_action_param * par)36 static unsigned int xt_ct_target_v0(struct sk_buff *skb,
37 const struct xt_action_param *par)
38 {
39 const struct xt_ct_target_info *info = par->targinfo;
40 struct nf_conn *ct = info->ct;
41
42 return xt_ct_target(skb, ct);
43 }
44
xt_ct_target_v1(struct sk_buff * skb,const struct xt_action_param * par)45 static unsigned int xt_ct_target_v1(struct sk_buff *skb,
46 const struct xt_action_param *par)
47 {
48 const struct xt_ct_target_info_v1 *info = par->targinfo;
49 struct nf_conn *ct = info->ct;
50
51 return xt_ct_target(skb, ct);
52 }
53
xt_ct_find_proto(const struct xt_tgchk_param * par)54 static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
55 {
56 if (par->family == NFPROTO_IPV4) {
57 const struct ipt_entry *e = par->entryinfo;
58
59 if (e->ip.invflags & IPT_INV_PROTO)
60 return 0;
61 return e->ip.proto;
62 } else if (par->family == NFPROTO_IPV6) {
63 const struct ip6t_entry *e = par->entryinfo;
64
65 if (e->ipv6.invflags & IP6T_INV_PROTO)
66 return 0;
67 return e->ipv6.proto;
68 } else
69 return 0;
70 }
71
72 static int
xt_ct_set_helper(struct nf_conn * ct,const char * helper_name,const struct xt_tgchk_param * par)73 xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
74 const struct xt_tgchk_param *par)
75 {
76 struct nf_conntrack_helper *helper;
77 struct nf_conn_help *help;
78 u8 proto;
79
80 proto = xt_ct_find_proto(par);
81 if (!proto) {
82 pr_info_ratelimited("You must specify a L4 protocol and not use inversions on it\n");
83 return -ENOENT;
84 }
85
86 helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
87 proto);
88 if (helper == NULL) {
89 pr_info_ratelimited("No such helper \"%s\"\n", helper_name);
90 return -ENOENT;
91 }
92
93 help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
94 if (help == NULL) {
95 nf_conntrack_helper_put(helper);
96 return -ENOMEM;
97 }
98
99 help->helper = helper;
100 return 0;
101 }
102
103 static int
xt_ct_set_timeout(struct nf_conn * ct,const struct xt_tgchk_param * par,const char * timeout_name)104 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
105 const char *timeout_name)
106 {
107 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
108 const struct nf_conntrack_l4proto *l4proto;
109 u8 proto;
110
111 proto = xt_ct_find_proto(par);
112 if (!proto) {
113 pr_info_ratelimited("You must specify a L4 protocol and not "
114 "use inversions on it");
115 return -EINVAL;
116 }
117 l4proto = nf_ct_l4proto_find(proto);
118 return nf_ct_set_timeout(par->net, ct, par->family, l4proto->l4proto,
119 timeout_name);
120
121 #else
122 return -EOPNOTSUPP;
123 #endif
124 }
125
xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 * info)126 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
127 {
128 switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
129 XT_CT_ZONE_DIR_REPL)) {
130 case XT_CT_ZONE_DIR_ORIG:
131 return NF_CT_ZONE_DIR_ORIG;
132 case XT_CT_ZONE_DIR_REPL:
133 return NF_CT_ZONE_DIR_REPL;
134 default:
135 return NF_CT_DEFAULT_ZONE_DIR;
136 }
137 }
138
xt_ct_tg_check(const struct xt_tgchk_param * par,struct xt_ct_target_info_v1 * info)139 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
140 struct xt_ct_target_info_v1 *info)
141 {
142 struct nf_conntrack_zone zone;
143 struct nf_conn_help *help;
144 struct nf_conn *ct;
145 int ret = -EOPNOTSUPP;
146
147 if (info->flags & XT_CT_NOTRACK) {
148 ct = NULL;
149 goto out;
150 }
151
152 #ifndef CONFIG_NF_CONNTRACK_ZONES
153 if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
154 XT_CT_ZONE_DIR_REPL |
155 XT_CT_ZONE_MARK))
156 goto err1;
157 #endif
158
159 ret = nf_ct_netns_get(par->net, par->family);
160 if (ret < 0)
161 goto err1;
162
163 memset(&zone, 0, sizeof(zone));
164 zone.id = info->zone;
165 zone.dir = xt_ct_flags_to_dir(info);
166 if (info->flags & XT_CT_ZONE_MARK)
167 zone.flags |= NF_CT_FLAG_MARK;
168
169 ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
170 if (!ct) {
171 ret = -ENOMEM;
172 goto err2;
173 }
174
175 if ((info->ct_events || info->exp_events) &&
176 !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
177 GFP_KERNEL)) {
178 ret = -EINVAL;
179 goto err3;
180 }
181
182 if (info->helper[0]) {
183 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
184 ret = -ENAMETOOLONG;
185 goto err3;
186 }
187
188 ret = xt_ct_set_helper(ct, info->helper, par);
189 if (ret < 0)
190 goto err3;
191 }
192
193 if (info->timeout[0]) {
194 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
195 ret = -ENAMETOOLONG;
196 goto err4;
197 }
198
199 ret = xt_ct_set_timeout(ct, par, info->timeout);
200 if (ret < 0)
201 goto err4;
202 }
203 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
204 nf_conntrack_get(&ct->ct_general);
205 out:
206 info->ct = ct;
207 return 0;
208
209 err4:
210 help = nfct_help(ct);
211 if (help)
212 nf_conntrack_helper_put(help->helper);
213 err3:
214 nf_ct_tmpl_free(ct);
215 err2:
216 nf_ct_netns_put(par->net, par->family);
217 err1:
218 return ret;
219 }
220
xt_ct_tg_check_v0(const struct xt_tgchk_param * par)221 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
222 {
223 struct xt_ct_target_info *info = par->targinfo;
224 struct xt_ct_target_info_v1 info_v1 = {
225 .flags = info->flags,
226 .zone = info->zone,
227 .ct_events = info->ct_events,
228 .exp_events = info->exp_events,
229 };
230 int ret;
231
232 if (info->flags & ~XT_CT_NOTRACK)
233 return -EINVAL;
234
235 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
236
237 ret = xt_ct_tg_check(par, &info_v1);
238 if (ret < 0)
239 return ret;
240
241 info->ct = info_v1.ct;
242
243 return ret;
244 }
245
xt_ct_tg_check_v1(const struct xt_tgchk_param * par)246 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
247 {
248 struct xt_ct_target_info_v1 *info = par->targinfo;
249
250 if (info->flags & ~XT_CT_NOTRACK)
251 return -EINVAL;
252
253 return xt_ct_tg_check(par, par->targinfo);
254 }
255
xt_ct_tg_check_v2(const struct xt_tgchk_param * par)256 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
257 {
258 struct xt_ct_target_info_v1 *info = par->targinfo;
259
260 if (info->flags & ~XT_CT_MASK)
261 return -EINVAL;
262
263 return xt_ct_tg_check(par, par->targinfo);
264 }
265
xt_ct_tg_destroy(const struct xt_tgdtor_param * par,struct xt_ct_target_info_v1 * info)266 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
267 struct xt_ct_target_info_v1 *info)
268 {
269 struct nf_conn *ct = info->ct;
270 struct nf_conn_help *help;
271
272 if (ct) {
273 help = nfct_help(ct);
274 if (help)
275 nf_conntrack_helper_put(help->helper);
276
277 nf_ct_netns_put(par->net, par->family);
278
279 nf_ct_destroy_timeout(ct);
280 nf_ct_put(info->ct);
281 }
282 }
283
xt_ct_tg_destroy_v0(const struct xt_tgdtor_param * par)284 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
285 {
286 struct xt_ct_target_info *info = par->targinfo;
287 struct xt_ct_target_info_v1 info_v1 = {
288 .flags = info->flags,
289 .zone = info->zone,
290 .ct_events = info->ct_events,
291 .exp_events = info->exp_events,
292 .ct = info->ct,
293 };
294 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
295
296 xt_ct_tg_destroy(par, &info_v1);
297 }
298
xt_ct_tg_destroy_v1(const struct xt_tgdtor_param * par)299 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
300 {
301 xt_ct_tg_destroy(par, par->targinfo);
302 }
303
304 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
305 {
306 .name = "CT",
307 .family = NFPROTO_UNSPEC,
308 .targetsize = sizeof(struct xt_ct_target_info),
309 .usersize = offsetof(struct xt_ct_target_info, ct),
310 .checkentry = xt_ct_tg_check_v0,
311 .destroy = xt_ct_tg_destroy_v0,
312 .target = xt_ct_target_v0,
313 .table = "raw",
314 .me = THIS_MODULE,
315 },
316 {
317 .name = "CT",
318 .family = NFPROTO_UNSPEC,
319 .revision = 1,
320 .targetsize = sizeof(struct xt_ct_target_info_v1),
321 .usersize = offsetof(struct xt_ct_target_info, ct),
322 .checkentry = xt_ct_tg_check_v1,
323 .destroy = xt_ct_tg_destroy_v1,
324 .target = xt_ct_target_v1,
325 .table = "raw",
326 .me = THIS_MODULE,
327 },
328 {
329 .name = "CT",
330 .family = NFPROTO_UNSPEC,
331 .revision = 2,
332 .targetsize = sizeof(struct xt_ct_target_info_v1),
333 .usersize = offsetof(struct xt_ct_target_info, ct),
334 .checkentry = xt_ct_tg_check_v2,
335 .destroy = xt_ct_tg_destroy_v1,
336 .target = xt_ct_target_v1,
337 .table = "raw",
338 .me = THIS_MODULE,
339 },
340 };
341
342 static unsigned int
notrack_tg(struct sk_buff * skb,const struct xt_action_param * par)343 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
344 {
345 /* Previously seen (loopback)? Ignore. */
346 if (skb->_nfct != 0)
347 return XT_CONTINUE;
348
349 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
350
351 return XT_CONTINUE;
352 }
353
354 static struct xt_target notrack_tg_reg __read_mostly = {
355 .name = "NOTRACK",
356 .revision = 0,
357 .family = NFPROTO_UNSPEC,
358 .target = notrack_tg,
359 .table = "raw",
360 .me = THIS_MODULE,
361 };
362
xt_ct_tg_init(void)363 static int __init xt_ct_tg_init(void)
364 {
365 int ret;
366
367 ret = xt_register_target(¬rack_tg_reg);
368 if (ret < 0)
369 return ret;
370
371 ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
372 if (ret < 0) {
373 xt_unregister_target(¬rack_tg_reg);
374 return ret;
375 }
376 return 0;
377 }
378
xt_ct_tg_exit(void)379 static void __exit xt_ct_tg_exit(void)
380 {
381 xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
382 xt_unregister_target(¬rack_tg_reg);
383 }
384
385 module_init(xt_ct_tg_init);
386 module_exit(xt_ct_tg_exit);
387
388 MODULE_LICENSE("GPL");
389 MODULE_DESCRIPTION("Xtables: connection tracking target");
390 MODULE_ALIAS("ipt_CT");
391 MODULE_ALIAS("ip6t_CT");
392 MODULE_ALIAS("ipt_NOTRACK");
393 MODULE_ALIAS("ip6t_NOTRACK");
394
