xref: /linux/net/netfilter/nfnetlink_cttimeout.c (revision 44f57d78) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
4  * (C) 2012 by Vyatta Inc. <http://www.vyatta.com>
5  */
6 #include <linux/init.h>
7 #include <linux/module.h>
8 #include <linux/kernel.h>
9 #include <linux/rculist.h>
10 #include <linux/rculist_nulls.h>
11 #include <linux/types.h>
12 #include <linux/timer.h>
13 #include <linux/security.h>
14 #include <linux/skbuff.h>
15 #include <linux/errno.h>
16 #include <linux/netlink.h>
17 #include <linux/spinlock.h>
18 #include <linux/interrupt.h>
19 #include <linux/slab.h>
20 
21 #include <linux/netfilter.h>
22 #include <net/netlink.h>
23 #include <net/sock.h>
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_core.h>
26 #include <net/netfilter/nf_conntrack_l4proto.h>
27 #include <net/netfilter/nf_conntrack_tuple.h>
28 #include <net/netfilter/nf_conntrack_timeout.h>
29 
30 #include <linux/netfilter/nfnetlink.h>
31 #include <linux/netfilter/nfnetlink_cttimeout.h>
32 
33 MODULE_LICENSE("GPL");
34 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
35 MODULE_DESCRIPTION("cttimeout: Extended Netfilter Connection Tracking timeout tuning");
36 
37 static const struct nla_policy cttimeout_nla_policy[CTA_TIMEOUT_MAX+1] = {
38 	[CTA_TIMEOUT_NAME]	= { .type = NLA_NUL_STRING,
39 				    .len  = CTNL_TIMEOUT_NAME_MAX - 1},
40 	[CTA_TIMEOUT_L3PROTO]	= { .type = NLA_U16 },
41 	[CTA_TIMEOUT_L4PROTO]	= { .type = NLA_U8 },
42 	[CTA_TIMEOUT_DATA]	= { .type = NLA_NESTED },
43 };
44 
45 static int
46 ctnl_timeout_parse_policy(void *timeout,
47 			  const struct nf_conntrack_l4proto *l4proto,
48 			  struct net *net, const struct nlattr *attr)
49 {
50 	struct nlattr **tb;
51 	int ret = 0;
52 
53 	tb = kcalloc(l4proto->ctnl_timeout.nlattr_max + 1, sizeof(*tb),
54 		     GFP_KERNEL);
55 
56 	if (!tb)
57 		return -ENOMEM;
58 
59 	ret = nla_parse_nested_deprecated(tb,
60 					  l4proto->ctnl_timeout.nlattr_max,
61 					  attr,
62 					  l4proto->ctnl_timeout.nla_policy,
63 					  NULL);
64 	if (ret < 0)
65 		goto err;
66 
67 	ret = l4proto->ctnl_timeout.nlattr_to_obj(tb, net, timeout);
68 
69 err:
70 	kfree(tb);
71 	return ret;
72 }
73 
74 static int cttimeout_new_timeout(struct net *net, struct sock *ctnl,
75 				 struct sk_buff *skb,
76 				 const struct nlmsghdr *nlh,
77 				 const struct nlattr * const cda[],
78 				 struct netlink_ext_ack *extack)
79 {
80 	__u16 l3num;
81 	__u8 l4num;
82 	const struct nf_conntrack_l4proto *l4proto;
83 	struct ctnl_timeout *timeout, *matching = NULL;
84 	char *name;
85 	int ret;
86 
87 	if (!cda[CTA_TIMEOUT_NAME] ||
88 	    !cda[CTA_TIMEOUT_L3PROTO] ||
89 	    !cda[CTA_TIMEOUT_L4PROTO] ||
90 	    !cda[CTA_TIMEOUT_DATA])
91 		return -EINVAL;
92 
93 	name = nla_data(cda[CTA_TIMEOUT_NAME]);
94 	l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
95 	l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
96 
97 	list_for_each_entry(timeout, &net->nfct_timeout_list, head) {
98 		if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
99 			continue;
100 
101 		if (nlh->nlmsg_flags & NLM_F_EXCL)
102 			return -EEXIST;
103 
104 		matching = timeout;
105 		break;
106 	}
107 
108 	if (matching) {
109 		if (nlh->nlmsg_flags & NLM_F_REPLACE) {
110 			/* You cannot replace one timeout policy by another of
111 			 * different kind, sorry.
112 			 */
113 			if (matching->timeout.l3num != l3num ||
114 			    matching->timeout.l4proto->l4proto != l4num)
115 				return -EINVAL;
116 
117 			return ctnl_timeout_parse_policy(&matching->timeout.data,
118 							 matching->timeout.l4proto,
119 							 net, cda[CTA_TIMEOUT_DATA]);
120 		}
121 
122 		return -EBUSY;
123 	}
124 
125 	l4proto = nf_ct_l4proto_find(l4num);
126 
127 	/* This protocol is not supportted, skip. */
128 	if (l4proto->l4proto != l4num) {
129 		ret = -EOPNOTSUPP;
130 		goto err_proto_put;
131 	}
132 
133 	timeout = kzalloc(sizeof(struct ctnl_timeout) +
134 			  l4proto->ctnl_timeout.obj_size, GFP_KERNEL);
135 	if (timeout == NULL) {
136 		ret = -ENOMEM;
137 		goto err_proto_put;
138 	}
139 
140 	ret = ctnl_timeout_parse_policy(&timeout->timeout.data, l4proto, net,
141 					cda[CTA_TIMEOUT_DATA]);
142 	if (ret < 0)
143 		goto err;
144 
145 	strcpy(timeout->name, nla_data(cda[CTA_TIMEOUT_NAME]));
146 	timeout->timeout.l3num = l3num;
147 	timeout->timeout.l4proto = l4proto;
148 	refcount_set(&timeout->refcnt, 1);
149 	list_add_tail_rcu(&timeout->head, &net->nfct_timeout_list);
150 
151 	return 0;
152 err:
153 	kfree(timeout);
154 err_proto_put:
155 	return ret;
156 }
157 
158 static int
159 ctnl_timeout_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
160 		       int event, struct ctnl_timeout *timeout)
161 {
162 	struct nlmsghdr *nlh;
163 	struct nfgenmsg *nfmsg;
164 	unsigned int flags = portid ? NLM_F_MULTI : 0;
165 	const struct nf_conntrack_l4proto *l4proto = timeout->timeout.l4proto;
166 	struct nlattr *nest_parms;
167 	int ret;
168 
169 	event = nfnl_msg_type(NFNL_SUBSYS_CTNETLINK_TIMEOUT, event);
170 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
171 	if (nlh == NULL)
172 		goto nlmsg_failure;
173 
174 	nfmsg = nlmsg_data(nlh);
175 	nfmsg->nfgen_family = AF_UNSPEC;
176 	nfmsg->version = NFNETLINK_V0;
177 	nfmsg->res_id = 0;
178 
179 	if (nla_put_string(skb, CTA_TIMEOUT_NAME, timeout->name) ||
180 	    nla_put_be16(skb, CTA_TIMEOUT_L3PROTO,
181 			 htons(timeout->timeout.l3num)) ||
182 	    nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, l4proto->l4proto) ||
183 	    nla_put_be32(skb, CTA_TIMEOUT_USE,
184 			 htonl(refcount_read(&timeout->refcnt))))
185 		goto nla_put_failure;
186 
187 	nest_parms = nla_nest_start(skb, CTA_TIMEOUT_DATA);
188 	if (!nest_parms)
189 		goto nla_put_failure;
190 
191 	ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, &timeout->timeout.data);
192 	if (ret < 0)
193 		goto nla_put_failure;
194 
195 	nla_nest_end(skb, nest_parms);
196 
197 	nlmsg_end(skb, nlh);
198 	return skb->len;
199 
200 nlmsg_failure:
201 nla_put_failure:
202 	nlmsg_cancel(skb, nlh);
203 	return -1;
204 }
205 
206 static int
207 ctnl_timeout_dump(struct sk_buff *skb, struct netlink_callback *cb)
208 {
209 	struct net *net = sock_net(skb->sk);
210 	struct ctnl_timeout *cur, *last;
211 
212 	if (cb->args[2])
213 		return 0;
214 
215 	last = (struct ctnl_timeout *)cb->args[1];
216 	if (cb->args[1])
217 		cb->args[1] = 0;
218 
219 	rcu_read_lock();
220 	list_for_each_entry_rcu(cur, &net->nfct_timeout_list, head) {
221 		if (last) {
222 			if (cur != last)
223 				continue;
224 
225 			last = NULL;
226 		}
227 		if (ctnl_timeout_fill_info(skb, NETLINK_CB(cb->skb).portid,
228 					   cb->nlh->nlmsg_seq,
229 					   NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
230 					   IPCTNL_MSG_TIMEOUT_NEW, cur) < 0) {
231 			cb->args[1] = (unsigned long)cur;
232 			break;
233 		}
234 	}
235 	if (!cb->args[1])
236 		cb->args[2] = 1;
237 	rcu_read_unlock();
238 	return skb->len;
239 }
240 
241 static int cttimeout_get_timeout(struct net *net, struct sock *ctnl,
242 				 struct sk_buff *skb,
243 				 const struct nlmsghdr *nlh,
244 				 const struct nlattr * const cda[],
245 				 struct netlink_ext_ack *extack)
246 {
247 	int ret = -ENOENT;
248 	char *name;
249 	struct ctnl_timeout *cur;
250 
251 	if (nlh->nlmsg_flags & NLM_F_DUMP) {
252 		struct netlink_dump_control c = {
253 			.dump = ctnl_timeout_dump,
254 		};
255 		return netlink_dump_start(ctnl, skb, nlh, &c);
256 	}
257 
258 	if (!cda[CTA_TIMEOUT_NAME])
259 		return -EINVAL;
260 	name = nla_data(cda[CTA_TIMEOUT_NAME]);
261 
262 	list_for_each_entry(cur, &net->nfct_timeout_list, head) {
263 		struct sk_buff *skb2;
264 
265 		if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
266 			continue;
267 
268 		skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
269 		if (skb2 == NULL) {
270 			ret = -ENOMEM;
271 			break;
272 		}
273 
274 		ret = ctnl_timeout_fill_info(skb2, NETLINK_CB(skb).portid,
275 					     nlh->nlmsg_seq,
276 					     NFNL_MSG_TYPE(nlh->nlmsg_type),
277 					     IPCTNL_MSG_TIMEOUT_NEW, cur);
278 		if (ret <= 0) {
279 			kfree_skb(skb2);
280 			break;
281 		}
282 		ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid,
283 					MSG_DONTWAIT);
284 		if (ret > 0)
285 			ret = 0;
286 
287 		/* this avoids a loop in nfnetlink. */
288 		return ret == -EAGAIN ? -ENOBUFS : ret;
289 	}
290 	return ret;
291 }
292 
293 /* try to delete object, fail if it is still in use. */
294 static int ctnl_timeout_try_del(struct net *net, struct ctnl_timeout *timeout)
295 {
296 	int ret = 0;
297 
298 	/* We want to avoid races with ctnl_timeout_put. So only when the
299 	 * current refcnt is 1, we decrease it to 0.
300 	 */
301 	if (refcount_dec_if_one(&timeout->refcnt)) {
302 		/* We are protected by nfnl mutex. */
303 		list_del_rcu(&timeout->head);
304 		nf_ct_untimeout(net, &timeout->timeout);
305 		kfree_rcu(timeout, rcu_head);
306 	} else {
307 		ret = -EBUSY;
308 	}
309 	return ret;
310 }
311 
312 static int cttimeout_del_timeout(struct net *net, struct sock *ctnl,
313 				 struct sk_buff *skb,
314 				 const struct nlmsghdr *nlh,
315 				 const struct nlattr * const cda[],
316 				 struct netlink_ext_ack *extack)
317 {
318 	struct ctnl_timeout *cur, *tmp;
319 	int ret = -ENOENT;
320 	char *name;
321 
322 	if (!cda[CTA_TIMEOUT_NAME]) {
323 		list_for_each_entry_safe(cur, tmp, &net->nfct_timeout_list,
324 					 head)
325 			ctnl_timeout_try_del(net, cur);
326 
327 		return 0;
328 	}
329 	name = nla_data(cda[CTA_TIMEOUT_NAME]);
330 
331 	list_for_each_entry(cur, &net->nfct_timeout_list, head) {
332 		if (strncmp(cur->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
333 			continue;
334 
335 		ret = ctnl_timeout_try_del(net, cur);
336 		if (ret < 0)
337 			return ret;
338 
339 		break;
340 	}
341 	return ret;
342 }
343 
344 static int cttimeout_default_set(struct net *net, struct sock *ctnl,
345 				 struct sk_buff *skb,
346 				 const struct nlmsghdr *nlh,
347 				 const struct nlattr * const cda[],
348 				 struct netlink_ext_ack *extack)
349 {
350 	const struct nf_conntrack_l4proto *l4proto;
351 	__u8 l4num;
352 	int ret;
353 
354 	if (!cda[CTA_TIMEOUT_L3PROTO] ||
355 	    !cda[CTA_TIMEOUT_L4PROTO] ||
356 	    !cda[CTA_TIMEOUT_DATA])
357 		return -EINVAL;
358 
359 	l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
360 	l4proto = nf_ct_l4proto_find(l4num);
361 
362 	/* This protocol is not supported, skip. */
363 	if (l4proto->l4proto != l4num) {
364 		ret = -EOPNOTSUPP;
365 		goto err;
366 	}
367 
368 	ret = ctnl_timeout_parse_policy(NULL, l4proto, net,
369 					cda[CTA_TIMEOUT_DATA]);
370 	if (ret < 0)
371 		goto err;
372 
373 	return 0;
374 err:
375 	return ret;
376 }
377 
378 static int
379 cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid,
380 			    u32 seq, u32 type, int event, u16 l3num,
381 			    const struct nf_conntrack_l4proto *l4proto,
382 			    const unsigned int *timeouts)
383 {
384 	struct nlmsghdr *nlh;
385 	struct nfgenmsg *nfmsg;
386 	unsigned int flags = portid ? NLM_F_MULTI : 0;
387 	struct nlattr *nest_parms;
388 	int ret;
389 
390 	event = nfnl_msg_type(NFNL_SUBSYS_CTNETLINK_TIMEOUT, event);
391 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
392 	if (nlh == NULL)
393 		goto nlmsg_failure;
394 
395 	nfmsg = nlmsg_data(nlh);
396 	nfmsg->nfgen_family = AF_UNSPEC;
397 	nfmsg->version = NFNETLINK_V0;
398 	nfmsg->res_id = 0;
399 
400 	if (nla_put_be16(skb, CTA_TIMEOUT_L3PROTO, htons(l3num)) ||
401 	    nla_put_u8(skb, CTA_TIMEOUT_L4PROTO, l4proto->l4proto))
402 		goto nla_put_failure;
403 
404 	nest_parms = nla_nest_start(skb, CTA_TIMEOUT_DATA);
405 	if (!nest_parms)
406 		goto nla_put_failure;
407 
408 	ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, timeouts);
409 	if (ret < 0)
410 		goto nla_put_failure;
411 
412 	nla_nest_end(skb, nest_parms);
413 
414 	nlmsg_end(skb, nlh);
415 	return skb->len;
416 
417 nlmsg_failure:
418 nla_put_failure:
419 	nlmsg_cancel(skb, nlh);
420 	return -1;
421 }
422 
423 static int cttimeout_default_get(struct net *net, struct sock *ctnl,
424 				 struct sk_buff *skb,
425 				 const struct nlmsghdr *nlh,
426 				 const struct nlattr * const cda[],
427 				 struct netlink_ext_ack *extack)
428 {
429 	const struct nf_conntrack_l4proto *l4proto;
430 	unsigned int *timeouts = NULL;
431 	struct sk_buff *skb2;
432 	int ret, err;
433 	__u16 l3num;
434 	__u8 l4num;
435 
436 	if (!cda[CTA_TIMEOUT_L3PROTO] || !cda[CTA_TIMEOUT_L4PROTO])
437 		return -EINVAL;
438 
439 	l3num = ntohs(nla_get_be16(cda[CTA_TIMEOUT_L3PROTO]));
440 	l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
441 	l4proto = nf_ct_l4proto_find(l4num);
442 
443 	err = -EOPNOTSUPP;
444 	if (l4proto->l4proto != l4num)
445 		goto err;
446 
447 	switch (l4proto->l4proto) {
448 	case IPPROTO_ICMP:
449 		timeouts = &nf_icmp_pernet(net)->timeout;
450 		break;
451 	case IPPROTO_TCP:
452 		timeouts = nf_tcp_pernet(net)->timeouts;
453 		break;
454 	case IPPROTO_UDP: /* fallthrough */
455 	case IPPROTO_UDPLITE:
456 		timeouts = nf_udp_pernet(net)->timeouts;
457 		break;
458 	case IPPROTO_DCCP:
459 #ifdef CONFIG_NF_CT_PROTO_DCCP
460 		timeouts = nf_dccp_pernet(net)->dccp_timeout;
461 #endif
462 		break;
463 	case IPPROTO_ICMPV6:
464 		timeouts = &nf_icmpv6_pernet(net)->timeout;
465 		break;
466 	case IPPROTO_SCTP:
467 #ifdef CONFIG_NF_CT_PROTO_SCTP
468 		timeouts = nf_sctp_pernet(net)->timeouts;
469 #endif
470 		break;
471 	case IPPROTO_GRE:
472 #ifdef CONFIG_NF_CT_PROTO_GRE
473 		timeouts = nf_gre_pernet(net)->timeouts;
474 #endif
475 		break;
476 	case 255:
477 		timeouts = &nf_generic_pernet(net)->timeout;
478 		break;
479 	default:
480 		WARN_ONCE(1, "Missing timeouts for proto %d", l4proto->l4proto);
481 		break;
482 	}
483 
484 	if (!timeouts)
485 		goto err;
486 
487 	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
488 	if (skb2 == NULL) {
489 		err = -ENOMEM;
490 		goto err;
491 	}
492 
493 	ret = cttimeout_default_fill_info(net, skb2, NETLINK_CB(skb).portid,
494 					  nlh->nlmsg_seq,
495 					  NFNL_MSG_TYPE(nlh->nlmsg_type),
496 					  IPCTNL_MSG_TIMEOUT_DEFAULT_SET,
497 					  l3num, l4proto, timeouts);
498 	if (ret <= 0) {
499 		kfree_skb(skb2);
500 		err = -ENOMEM;
501 		goto err;
502 	}
503 	ret = netlink_unicast(ctnl, skb2, NETLINK_CB(skb).portid, MSG_DONTWAIT);
504 	if (ret > 0)
505 		ret = 0;
506 
507 	/* this avoids a loop in nfnetlink. */
508 	return ret == -EAGAIN ? -ENOBUFS : ret;
509 err:
510 	return err;
511 }
512 
513 static struct nf_ct_timeout *ctnl_timeout_find_get(struct net *net,
514 						   const char *name)
515 {
516 	struct ctnl_timeout *timeout, *matching = NULL;
517 
518 	list_for_each_entry_rcu(timeout, &net->nfct_timeout_list, head) {
519 		if (strncmp(timeout->name, name, CTNL_TIMEOUT_NAME_MAX) != 0)
520 			continue;
521 
522 		if (!try_module_get(THIS_MODULE))
523 			goto err;
524 
525 		if (!refcount_inc_not_zero(&timeout->refcnt)) {
526 			module_put(THIS_MODULE);
527 			goto err;
528 		}
529 		matching = timeout;
530 		break;
531 	}
532 err:
533 	return matching ? &matching->timeout : NULL;
534 }
535 
536 static void ctnl_timeout_put(struct nf_ct_timeout *t)
537 {
538 	struct ctnl_timeout *timeout =
539 		container_of(t, struct ctnl_timeout, timeout);
540 
541 	if (refcount_dec_and_test(&timeout->refcnt))
542 		kfree_rcu(timeout, rcu_head);
543 
544 	module_put(THIS_MODULE);
545 }
546 
547 static const struct nfnl_callback cttimeout_cb[IPCTNL_MSG_TIMEOUT_MAX] = {
548 	[IPCTNL_MSG_TIMEOUT_NEW]	= { .call = cttimeout_new_timeout,
549 					    .attr_count = CTA_TIMEOUT_MAX,
550 					    .policy = cttimeout_nla_policy },
551 	[IPCTNL_MSG_TIMEOUT_GET]	= { .call = cttimeout_get_timeout,
552 					    .attr_count = CTA_TIMEOUT_MAX,
553 					    .policy = cttimeout_nla_policy },
554 	[IPCTNL_MSG_TIMEOUT_DELETE]	= { .call = cttimeout_del_timeout,
555 					    .attr_count = CTA_TIMEOUT_MAX,
556 					    .policy = cttimeout_nla_policy },
557 	[IPCTNL_MSG_TIMEOUT_DEFAULT_SET]= { .call = cttimeout_default_set,
558 					    .attr_count = CTA_TIMEOUT_MAX,
559 					    .policy = cttimeout_nla_policy },
560 	[IPCTNL_MSG_TIMEOUT_DEFAULT_GET]= { .call = cttimeout_default_get,
561 					    .attr_count = CTA_TIMEOUT_MAX,
562 					    .policy = cttimeout_nla_policy },
563 };
564 
565 static const struct nfnetlink_subsystem cttimeout_subsys = {
566 	.name				= "conntrack_timeout",
567 	.subsys_id			= NFNL_SUBSYS_CTNETLINK_TIMEOUT,
568 	.cb_count			= IPCTNL_MSG_TIMEOUT_MAX,
569 	.cb				= cttimeout_cb,
570 };
571 
572 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTNETLINK_TIMEOUT);
573 
574 static int __net_init cttimeout_net_init(struct net *net)
575 {
576 	INIT_LIST_HEAD(&net->nfct_timeout_list);
577 
578 	return 0;
579 }
580 
581 static void __net_exit cttimeout_net_exit(struct net *net)
582 {
583 	struct ctnl_timeout *cur, *tmp;
584 
585 	nf_ct_unconfirmed_destroy(net);
586 	nf_ct_untimeout(net, NULL);
587 
588 	list_for_each_entry_safe(cur, tmp, &net->nfct_timeout_list, head) {
589 		list_del_rcu(&cur->head);
590 
591 		if (refcount_dec_and_test(&cur->refcnt))
592 			kfree_rcu(cur, rcu_head);
593 	}
594 }
595 
596 static struct pernet_operations cttimeout_ops = {
597 	.init	= cttimeout_net_init,
598 	.exit	= cttimeout_net_exit,
599 };
600 
601 static int __init cttimeout_init(void)
602 {
603 	int ret;
604 
605 	ret = register_pernet_subsys(&cttimeout_ops);
606 	if (ret < 0)
607 		return ret;
608 
609 	ret = nfnetlink_subsys_register(&cttimeout_subsys);
610 	if (ret < 0) {
611 		pr_err("cttimeout_init: cannot register cttimeout with "
612 			"nfnetlink.\n");
613 		goto err_out;
614 	}
615 	RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, ctnl_timeout_find_get);
616 	RCU_INIT_POINTER(nf_ct_timeout_put_hook, ctnl_timeout_put);
617 	return 0;
618 
619 err_out:
620 	unregister_pernet_subsys(&cttimeout_ops);
621 	return ret;
622 }
623 
624 static void __exit cttimeout_exit(void)
625 {
626 	nfnetlink_subsys_unregister(&cttimeout_subsys);
627 
628 	unregister_pernet_subsys(&cttimeout_ops);
629 	RCU_INIT_POINTER(nf_ct_timeout_find_get_hook, NULL);
630 	RCU_INIT_POINTER(nf_ct_timeout_put_hook, NULL);
631 	synchronize_rcu();
632 }
633 
634 module_init(cttimeout_init);
635 module_exit(cttimeout_exit);
636