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 refcount_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 rcu_assign_pointer(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_put_helper(struct nf_conn_help * help)139 static void xt_ct_put_helper(struct nf_conn_help *help)
140 {
141 struct nf_conntrack_helper *helper;
142
143 if (!help)
144 return;
145
146 /* not yet exposed to other cpus, or ruleset
147 * already detached (post-replacement).
148 */
149 helper = rcu_dereference_raw(help->helper);
150 if (helper)
151 nf_conntrack_helper_put(helper);
152 }
153
xt_ct_tg_check(const struct xt_tgchk_param * par,struct xt_ct_target_info_v1 * info)154 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
155 struct xt_ct_target_info_v1 *info)
156 {
157 struct nf_conntrack_zone zone;
158 struct nf_conn_help *help;
159 struct nf_conn *ct;
160 int ret = -EOPNOTSUPP;
161
162 if (info->flags & XT_CT_NOTRACK) {
163 ct = NULL;
164 goto out;
165 }
166
167 #ifndef CONFIG_NF_CONNTRACK_ZONES
168 if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
169 XT_CT_ZONE_DIR_REPL |
170 XT_CT_ZONE_MARK))
171 goto err1;
172 #endif
173
174 ret = nf_ct_netns_get(par->net, par->family);
175 if (ret < 0)
176 goto err1;
177
178 memset(&zone, 0, sizeof(zone));
179 zone.id = info->zone;
180 zone.dir = xt_ct_flags_to_dir(info);
181 if (info->flags & XT_CT_ZONE_MARK)
182 zone.flags |= NF_CT_FLAG_MARK;
183
184 ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
185 if (!ct) {
186 ret = -ENOMEM;
187 goto err2;
188 }
189
190 if ((info->ct_events || info->exp_events) &&
191 !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
192 GFP_KERNEL)) {
193 ret = -EINVAL;
194 goto err3;
195 }
196
197 if (info->helper[0]) {
198 if (strnlen(info->helper, sizeof(info->helper)) == sizeof(info->helper)) {
199 ret = -ENAMETOOLONG;
200 goto err3;
201 }
202
203 ret = xt_ct_set_helper(ct, info->helper, par);
204 if (ret < 0)
205 goto err3;
206 }
207
208 if (info->timeout[0]) {
209 if (strnlen(info->timeout, sizeof(info->timeout)) == sizeof(info->timeout)) {
210 ret = -ENAMETOOLONG;
211 goto err4;
212 }
213
214 ret = xt_ct_set_timeout(ct, par, info->timeout);
215 if (ret < 0)
216 goto err4;
217 }
218 __set_bit(IPS_CONFIRMED_BIT, &ct->status);
219 out:
220 info->ct = ct;
221 return 0;
222
223 err4:
224 help = nfct_help(ct);
225 xt_ct_put_helper(help);
226 err3:
227 nf_ct_tmpl_free(ct);
228 err2:
229 nf_ct_netns_put(par->net, par->family);
230 err1:
231 return ret;
232 }
233
xt_ct_tg_check_v0(const struct xt_tgchk_param * par)234 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
235 {
236 struct xt_ct_target_info *info = par->targinfo;
237 struct xt_ct_target_info_v1 info_v1 = {
238 .flags = info->flags,
239 .zone = info->zone,
240 .ct_events = info->ct_events,
241 .exp_events = info->exp_events,
242 };
243 int ret;
244
245 if (info->flags & ~XT_CT_NOTRACK)
246 return -EINVAL;
247
248 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
249
250 ret = xt_ct_tg_check(par, &info_v1);
251 if (ret < 0)
252 return ret;
253
254 info->ct = info_v1.ct;
255
256 return ret;
257 }
258
xt_ct_tg_check_v1(const struct xt_tgchk_param * par)259 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
260 {
261 struct xt_ct_target_info_v1 *info = par->targinfo;
262
263 if (info->flags & ~XT_CT_NOTRACK)
264 return -EINVAL;
265
266 return xt_ct_tg_check(par, par->targinfo);
267 }
268
xt_ct_tg_check_v2(const struct xt_tgchk_param * par)269 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
270 {
271 struct xt_ct_target_info_v1 *info = par->targinfo;
272
273 if (info->flags & ~XT_CT_MASK)
274 return -EINVAL;
275
276 return xt_ct_tg_check(par, par->targinfo);
277 }
278
xt_ct_tg_destroy(const struct xt_tgdtor_param * par,struct xt_ct_target_info_v1 * info)279 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
280 struct xt_ct_target_info_v1 *info)
281 {
282 struct nf_conn *ct = info->ct;
283 struct nf_conn_help *help;
284
285 if (ct) {
286 help = nfct_help(ct);
287 xt_ct_put_helper(help);
288
289 nf_ct_netns_put(par->net, par->family);
290
291 nf_ct_destroy_timeout(ct);
292 nf_ct_put(info->ct);
293 }
294 }
295
xt_ct_tg_destroy_v0(const struct xt_tgdtor_param * par)296 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
297 {
298 struct xt_ct_target_info *info = par->targinfo;
299 struct xt_ct_target_info_v1 info_v1 = {
300 .flags = info->flags,
301 .zone = info->zone,
302 .ct_events = info->ct_events,
303 .exp_events = info->exp_events,
304 .ct = info->ct,
305 };
306 memcpy(info_v1.helper, info->helper, sizeof(info->helper));
307
308 xt_ct_tg_destroy(par, &info_v1);
309 }
310
xt_ct_tg_destroy_v1(const struct xt_tgdtor_param * par)311 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
312 {
313 xt_ct_tg_destroy(par, par->targinfo);
314 }
315
316 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
317 {
318 .name = "CT",
319 .family = NFPROTO_UNSPEC,
320 .targetsize = sizeof(struct xt_ct_target_info),
321 .usersize = offsetof(struct xt_ct_target_info, ct),
322 .checkentry = xt_ct_tg_check_v0,
323 .destroy = xt_ct_tg_destroy_v0,
324 .target = xt_ct_target_v0,
325 .table = "raw",
326 .me = THIS_MODULE,
327 },
328 {
329 .name = "CT",
330 .family = NFPROTO_UNSPEC,
331 .revision = 1,
332 .targetsize = sizeof(struct xt_ct_target_info_v1),
333 .usersize = offsetof(struct xt_ct_target_info, ct),
334 .checkentry = xt_ct_tg_check_v1,
335 .destroy = xt_ct_tg_destroy_v1,
336 .target = xt_ct_target_v1,
337 .table = "raw",
338 .me = THIS_MODULE,
339 },
340 {
341 .name = "CT",
342 .family = NFPROTO_UNSPEC,
343 .revision = 2,
344 .targetsize = sizeof(struct xt_ct_target_info_v1),
345 .usersize = offsetof(struct xt_ct_target_info, ct),
346 .checkentry = xt_ct_tg_check_v2,
347 .destroy = xt_ct_tg_destroy_v1,
348 .target = xt_ct_target_v1,
349 .table = "raw",
350 .me = THIS_MODULE,
351 },
352 };
353
354 static unsigned int
notrack_tg(struct sk_buff * skb,const struct xt_action_param * par)355 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
356 {
357 /* Previously seen (loopback)? Ignore. */
358 if (skb->_nfct != 0)
359 return XT_CONTINUE;
360
361 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
362
363 return XT_CONTINUE;
364 }
365
366 static struct xt_target notrack_tg_reg __read_mostly = {
367 .name = "NOTRACK",
368 .revision = 0,
369 .family = NFPROTO_UNSPEC,
370 .target = notrack_tg,
371 .table = "raw",
372 .me = THIS_MODULE,
373 };
374
xt_ct_tg_init(void)375 static int __init xt_ct_tg_init(void)
376 {
377 int ret;
378
379 ret = xt_register_target(¬rack_tg_reg);
380 if (ret < 0)
381 return ret;
382
383 ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
384 if (ret < 0) {
385 xt_unregister_target(¬rack_tg_reg);
386 return ret;
387 }
388 return 0;
389 }
390
xt_ct_tg_exit(void)391 static void __exit xt_ct_tg_exit(void)
392 {
393 xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
394 xt_unregister_target(¬rack_tg_reg);
395 }
396
397 module_init(xt_ct_tg_init);
398 module_exit(xt_ct_tg_exit);
399
400 MODULE_LICENSE("GPL");
401 MODULE_DESCRIPTION("Xtables: connection tracking target");
402 MODULE_ALIAS("ipt_CT");
403 MODULE_ALIAS("ip6t_CT");
404 MODULE_ALIAS("ipt_NOTRACK");
405 MODULE_ALIAS("ip6t_NOTRACK");
406