xref: /openbmc/linux/net/netfilter/nfnetlink.c (revision 07c7c6bf) 
1 /* Netfilter messages via netlink socket. Allows for user space
2  * protocol helpers and general trouble making from userspace.
3  *
4  * (C) 2001 by Jay Schulist <jschlst@samba.org>,
5  * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
6  * (C) 2005-2017 by Pablo Neira Ayuso <pablo@netfilter.org>
7  *
8  * Initial netfilter messages via netlink development funded and
9  * generally made possible by Network Robots, Inc. (www.networkrobots.com)
10  *
11  * Further development of this code funded by Astaro AG (http://www.astaro.com)
12  *
13  * This software may be used and distributed according to the terms
14  * of the GNU General Public License, incorporated herein by reference.
15  */
16 
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/socket.h>
20 #include <linux/kernel.h>
21 #include <linux/string.h>
22 #include <linux/sockios.h>
23 #include <linux/net.h>
24 #include <linux/skbuff.h>
25 #include <linux/uaccess.h>
26 #include <net/sock.h>
27 #include <linux/init.h>
28 #include <linux/sched/signal.h>
29 
30 #include <net/netlink.h>
31 #include <linux/netfilter/nfnetlink.h>
32 
33 MODULE_LICENSE("GPL");
34 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
35 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
36 
37 #define nfnl_dereference_protected(id) \
38 	rcu_dereference_protected(table[(id)].subsys, \
39 				  lockdep_nfnl_is_held((id)))
40 
41 #define NFNL_MAX_ATTR_COUNT	32
42 
43 static struct {
44 	struct mutex				mutex;
45 	const struct nfnetlink_subsystem __rcu	*subsys;
46 } table[NFNL_SUBSYS_COUNT];
47 
48 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
49 	[NFNLGRP_CONNTRACK_NEW]		= NFNL_SUBSYS_CTNETLINK,
50 	[NFNLGRP_CONNTRACK_UPDATE]	= NFNL_SUBSYS_CTNETLINK,
51 	[NFNLGRP_CONNTRACK_DESTROY]	= NFNL_SUBSYS_CTNETLINK,
52 	[NFNLGRP_CONNTRACK_EXP_NEW]	= NFNL_SUBSYS_CTNETLINK_EXP,
53 	[NFNLGRP_CONNTRACK_EXP_UPDATE]	= NFNL_SUBSYS_CTNETLINK_EXP,
54 	[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
55 	[NFNLGRP_NFTABLES]		= NFNL_SUBSYS_NFTABLES,
56 	[NFNLGRP_ACCT_QUOTA]		= NFNL_SUBSYS_ACCT,
57 	[NFNLGRP_NFTRACE]		= NFNL_SUBSYS_NFTABLES,
58 };
59 
60 void nfnl_lock(__u8 subsys_id)
61 {
62 	mutex_lock(&table[subsys_id].mutex);
63 }
64 EXPORT_SYMBOL_GPL(nfnl_lock);
65 
66 void nfnl_unlock(__u8 subsys_id)
67 {
68 	mutex_unlock(&table[subsys_id].mutex);
69 }
70 EXPORT_SYMBOL_GPL(nfnl_unlock);
71 
72 #ifdef CONFIG_PROVE_LOCKING
73 bool lockdep_nfnl_is_held(u8 subsys_id)
74 {
75 	return lockdep_is_held(&table[subsys_id].mutex);
76 }
77 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
78 #endif
79 
80 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
81 {
82 	u8 cb_id;
83 
84 	/* Sanity-check attr_count size to avoid stack buffer overflow. */
85 	for (cb_id = 0; cb_id < n->cb_count; cb_id++)
86 		if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
87 			return -EINVAL;
88 
89 	nfnl_lock(n->subsys_id);
90 	if (table[n->subsys_id].subsys) {
91 		nfnl_unlock(n->subsys_id);
92 		return -EBUSY;
93 	}
94 	rcu_assign_pointer(table[n->subsys_id].subsys, n);
95 	nfnl_unlock(n->subsys_id);
96 
97 	return 0;
98 }
99 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
100 
101 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
102 {
103 	nfnl_lock(n->subsys_id);
104 	table[n->subsys_id].subsys = NULL;
105 	nfnl_unlock(n->subsys_id);
106 	synchronize_rcu();
107 	return 0;
108 }
109 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
110 
111 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
112 {
113 	u8 subsys_id = NFNL_SUBSYS_ID(type);
114 
115 	if (subsys_id >= NFNL_SUBSYS_COUNT)
116 		return NULL;
117 
118 	return rcu_dereference(table[subsys_id].subsys);
119 }
120 
121 static inline const struct nfnl_callback *
122 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
123 {
124 	u8 cb_id = NFNL_MSG_TYPE(type);
125 
126 	if (cb_id >= ss->cb_count)
127 		return NULL;
128 
129 	return &ss->cb[cb_id];
130 }
131 
132 int nfnetlink_has_listeners(struct net *net, unsigned int group)
133 {
134 	return netlink_has_listeners(net->nfnl, group);
135 }
136 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
137 
138 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
139 		   unsigned int group, int echo, gfp_t flags)
140 {
141 	return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
142 }
143 EXPORT_SYMBOL_GPL(nfnetlink_send);
144 
145 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
146 {
147 	return netlink_set_err(net->nfnl, portid, group, error);
148 }
149 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
150 
151 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
152 		      int flags)
153 {
154 	return netlink_unicast(net->nfnl, skb, portid, flags);
155 }
156 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
157 
158 /* Process one complete nfnetlink message. */
159 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
160 			     struct netlink_ext_ack *extack)
161 {
162 	struct net *net = sock_net(skb->sk);
163 	const struct nfnl_callback *nc;
164 	const struct nfnetlink_subsystem *ss;
165 	int type, err;
166 
167 	/* All the messages must at least contain nfgenmsg */
168 	if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
169 		return 0;
170 
171 	type = nlh->nlmsg_type;
172 replay:
173 	rcu_read_lock();
174 	ss = nfnetlink_get_subsys(type);
175 	if (!ss) {
176 #ifdef CONFIG_MODULES
177 		rcu_read_unlock();
178 		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
179 		rcu_read_lock();
180 		ss = nfnetlink_get_subsys(type);
181 		if (!ss)
182 #endif
183 		{
184 			rcu_read_unlock();
185 			return -EINVAL;
186 		}
187 	}
188 
189 	nc = nfnetlink_find_client(type, ss);
190 	if (!nc) {
191 		rcu_read_unlock();
192 		return -EINVAL;
193 	}
194 
195 	{
196 		int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
197 		u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
198 		struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
199 		struct nlattr *attr = (void *)nlh + min_len;
200 		int attrlen = nlh->nlmsg_len - min_len;
201 		__u8 subsys_id = NFNL_SUBSYS_ID(type);
202 
203 		/* Sanity-check NFNL_MAX_ATTR_COUNT */
204 		if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
205 			rcu_read_unlock();
206 			return -ENOMEM;
207 		}
208 
209 		err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
210 					   attr, attrlen,
211 					   ss->cb[cb_id].policy, extack);
212 		if (err < 0) {
213 			rcu_read_unlock();
214 			return err;
215 		}
216 
217 		if (nc->call_rcu) {
218 			err = nc->call_rcu(net, net->nfnl, skb, nlh,
219 					   (const struct nlattr **)cda,
220 					   extack);
221 			rcu_read_unlock();
222 		} else {
223 			rcu_read_unlock();
224 			nfnl_lock(subsys_id);
225 			if (nfnl_dereference_protected(subsys_id) != ss ||
226 			    nfnetlink_find_client(type, ss) != nc)
227 				err = -EAGAIN;
228 			else if (nc->call)
229 				err = nc->call(net, net->nfnl, skb, nlh,
230 					       (const struct nlattr **)cda,
231 					       extack);
232 			else
233 				err = -EINVAL;
234 			nfnl_unlock(subsys_id);
235 		}
236 		if (err == -EAGAIN)
237 			goto replay;
238 		return err;
239 	}
240 }
241 
242 struct nfnl_err {
243 	struct list_head	head;
244 	struct nlmsghdr		*nlh;
245 	int			err;
246 	struct netlink_ext_ack	extack;
247 };
248 
249 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
250 			const struct netlink_ext_ack *extack)
251 {
252 	struct nfnl_err *nfnl_err;
253 
254 	nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
255 	if (nfnl_err == NULL)
256 		return -ENOMEM;
257 
258 	nfnl_err->nlh = nlh;
259 	nfnl_err->err = err;
260 	nfnl_err->extack = *extack;
261 	list_add_tail(&nfnl_err->head, list);
262 
263 	return 0;
264 }
265 
266 static void nfnl_err_del(struct nfnl_err *nfnl_err)
267 {
268 	list_del(&nfnl_err->head);
269 	kfree(nfnl_err);
270 }
271 
272 static void nfnl_err_reset(struct list_head *err_list)
273 {
274 	struct nfnl_err *nfnl_err, *next;
275 
276 	list_for_each_entry_safe(nfnl_err, next, err_list, head)
277 		nfnl_err_del(nfnl_err);
278 }
279 
280 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
281 {
282 	struct nfnl_err *nfnl_err, *next;
283 
284 	list_for_each_entry_safe(nfnl_err, next, err_list, head) {
285 		netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
286 			    &nfnl_err->extack);
287 		nfnl_err_del(nfnl_err);
288 	}
289 }
290 
291 enum {
292 	NFNL_BATCH_FAILURE	= (1 << 0),
293 	NFNL_BATCH_DONE		= (1 << 1),
294 	NFNL_BATCH_REPLAY	= (1 << 2),
295 };
296 
297 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
298 				u16 subsys_id, u32 genid)
299 {
300 	struct sk_buff *oskb = skb;
301 	struct net *net = sock_net(skb->sk);
302 	const struct nfnetlink_subsystem *ss;
303 	const struct nfnl_callback *nc;
304 	struct netlink_ext_ack extack;
305 	LIST_HEAD(err_list);
306 	u32 status;
307 	int err;
308 
309 	if (subsys_id >= NFNL_SUBSYS_COUNT)
310 		return netlink_ack(skb, nlh, -EINVAL, NULL);
311 replay:
312 	status = 0;
313 
314 	skb = netlink_skb_clone(oskb, GFP_KERNEL);
315 	if (!skb)
316 		return netlink_ack(oskb, nlh, -ENOMEM, NULL);
317 
318 	nfnl_lock(subsys_id);
319 	ss = nfnl_dereference_protected(subsys_id);
320 	if (!ss) {
321 #ifdef CONFIG_MODULES
322 		nfnl_unlock(subsys_id);
323 		request_module("nfnetlink-subsys-%d", subsys_id);
324 		nfnl_lock(subsys_id);
325 		ss = nfnl_dereference_protected(subsys_id);
326 		if (!ss)
327 #endif
328 		{
329 			nfnl_unlock(subsys_id);
330 			netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
331 			return kfree_skb(skb);
332 		}
333 	}
334 
335 	if (!ss->valid_genid || !ss->commit || !ss->abort) {
336 		nfnl_unlock(subsys_id);
337 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
338 		return kfree_skb(skb);
339 	}
340 
341 	if (!try_module_get(ss->owner)) {
342 		nfnl_unlock(subsys_id);
343 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
344 		return kfree_skb(skb);
345 	}
346 
347 	if (!ss->valid_genid(net, genid)) {
348 		module_put(ss->owner);
349 		nfnl_unlock(subsys_id);
350 		netlink_ack(oskb, nlh, -ERESTART, NULL);
351 		return kfree_skb(skb);
352 	}
353 
354 	nfnl_unlock(subsys_id);
355 
356 	while (skb->len >= nlmsg_total_size(0)) {
357 		int msglen, type;
358 
359 		if (fatal_signal_pending(current)) {
360 			nfnl_err_reset(&err_list);
361 			err = -EINTR;
362 			status = NFNL_BATCH_FAILURE;
363 			goto done;
364 		}
365 
366 		memset(&extack, 0, sizeof(extack));
367 		nlh = nlmsg_hdr(skb);
368 		err = 0;
369 
370 		if (nlh->nlmsg_len < NLMSG_HDRLEN ||
371 		    skb->len < nlh->nlmsg_len ||
372 		    nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
373 			nfnl_err_reset(&err_list);
374 			status |= NFNL_BATCH_FAILURE;
375 			goto done;
376 		}
377 
378 		/* Only requests are handled by the kernel */
379 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
380 			err = -EINVAL;
381 			goto ack;
382 		}
383 
384 		type = nlh->nlmsg_type;
385 		if (type == NFNL_MSG_BATCH_BEGIN) {
386 			/* Malformed: Batch begin twice */
387 			nfnl_err_reset(&err_list);
388 			status |= NFNL_BATCH_FAILURE;
389 			goto done;
390 		} else if (type == NFNL_MSG_BATCH_END) {
391 			status |= NFNL_BATCH_DONE;
392 			goto done;
393 		} else if (type < NLMSG_MIN_TYPE) {
394 			err = -EINVAL;
395 			goto ack;
396 		}
397 
398 		/* We only accept a batch with messages for the same
399 		 * subsystem.
400 		 */
401 		if (NFNL_SUBSYS_ID(type) != subsys_id) {
402 			err = -EINVAL;
403 			goto ack;
404 		}
405 
406 		nc = nfnetlink_find_client(type, ss);
407 		if (!nc) {
408 			err = -EINVAL;
409 			goto ack;
410 		}
411 
412 		{
413 			int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
414 			u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
415 			struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
416 			struct nlattr *attr = (void *)nlh + min_len;
417 			int attrlen = nlh->nlmsg_len - min_len;
418 
419 			/* Sanity-check NFTA_MAX_ATTR */
420 			if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
421 				err = -ENOMEM;
422 				goto ack;
423 			}
424 
425 			err = nla_parse_deprecated(cda,
426 						   ss->cb[cb_id].attr_count,
427 						   attr, attrlen,
428 						   ss->cb[cb_id].policy, NULL);
429 			if (err < 0)
430 				goto ack;
431 
432 			if (nc->call_batch) {
433 				err = nc->call_batch(net, net->nfnl, skb, nlh,
434 						     (const struct nlattr **)cda,
435 						     &extack);
436 			}
437 
438 			/* The lock was released to autoload some module, we
439 			 * have to abort and start from scratch using the
440 			 * original skb.
441 			 */
442 			if (err == -EAGAIN) {
443 				status |= NFNL_BATCH_REPLAY;
444 				goto done;
445 			}
446 		}
447 ack:
448 		if (nlh->nlmsg_flags & NLM_F_ACK || err) {
449 			/* Errors are delivered once the full batch has been
450 			 * processed, this avoids that the same error is
451 			 * reported several times when replaying the batch.
452 			 */
453 			if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
454 				/* We failed to enqueue an error, reset the
455 				 * list of errors and send OOM to userspace
456 				 * pointing to the batch header.
457 				 */
458 				nfnl_err_reset(&err_list);
459 				netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
460 					    NULL);
461 				status |= NFNL_BATCH_FAILURE;
462 				goto done;
463 			}
464 			/* We don't stop processing the batch on errors, thus,
465 			 * userspace gets all the errors that the batch
466 			 * triggers.
467 			 */
468 			if (err)
469 				status |= NFNL_BATCH_FAILURE;
470 		}
471 
472 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
473 		if (msglen > skb->len)
474 			msglen = skb->len;
475 		skb_pull(skb, msglen);
476 	}
477 done:
478 	if (status & NFNL_BATCH_REPLAY) {
479 		ss->abort(net, oskb);
480 		nfnl_err_reset(&err_list);
481 		kfree_skb(skb);
482 		module_put(ss->owner);
483 		goto replay;
484 	} else if (status == NFNL_BATCH_DONE) {
485 		err = ss->commit(net, oskb);
486 		if (err == -EAGAIN) {
487 			status |= NFNL_BATCH_REPLAY;
488 			goto done;
489 		} else if (err) {
490 			ss->abort(net, oskb);
491 			netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
492 		}
493 	} else {
494 		ss->abort(net, oskb);
495 	}
496 	if (ss->cleanup)
497 		ss->cleanup(net);
498 
499 	nfnl_err_deliver(&err_list, oskb);
500 	kfree_skb(skb);
501 	module_put(ss->owner);
502 }
503 
504 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
505 	[NFNL_BATCH_GENID]	= { .type = NLA_U32 },
506 };
507 
508 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
509 {
510 	int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
511 	struct nlattr *attr = (void *)nlh + min_len;
512 	struct nlattr *cda[NFNL_BATCH_MAX + 1];
513 	int attrlen = nlh->nlmsg_len - min_len;
514 	struct nfgenmsg *nfgenmsg;
515 	int msglen, err;
516 	u32 gen_id = 0;
517 	u16 res_id;
518 
519 	msglen = NLMSG_ALIGN(nlh->nlmsg_len);
520 	if (msglen > skb->len)
521 		msglen = skb->len;
522 
523 	if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
524 		return;
525 
526 	err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
527 				   nfnl_batch_policy, NULL);
528 	if (err < 0) {
529 		netlink_ack(skb, nlh, err, NULL);
530 		return;
531 	}
532 	if (cda[NFNL_BATCH_GENID])
533 		gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
534 
535 	nfgenmsg = nlmsg_data(nlh);
536 	skb_pull(skb, msglen);
537 	/* Work around old nft using host byte order */
538 	if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
539 		res_id = NFNL_SUBSYS_NFTABLES;
540 	else
541 		res_id = ntohs(nfgenmsg->res_id);
542 
543 	nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
544 }
545 
546 static void nfnetlink_rcv(struct sk_buff *skb)
547 {
548 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
549 
550 	if (skb->len < NLMSG_HDRLEN ||
551 	    nlh->nlmsg_len < NLMSG_HDRLEN ||
552 	    skb->len < nlh->nlmsg_len)
553 		return;
554 
555 	if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
556 		netlink_ack(skb, nlh, -EPERM, NULL);
557 		return;
558 	}
559 
560 	if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
561 		nfnetlink_rcv_skb_batch(skb, nlh);
562 	else
563 		netlink_rcv_skb(skb, nfnetlink_rcv_msg);
564 }
565 
566 #ifdef CONFIG_MODULES
567 static int nfnetlink_bind(struct net *net, int group)
568 {
569 	const struct nfnetlink_subsystem *ss;
570 	int type;
571 
572 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
573 		return 0;
574 
575 	type = nfnl_group2type[group];
576 
577 	rcu_read_lock();
578 	ss = nfnetlink_get_subsys(type << 8);
579 	rcu_read_unlock();
580 	if (!ss)
581 		request_module("nfnetlink-subsys-%d", type);
582 	return 0;
583 }
584 #endif
585 
586 static int __net_init nfnetlink_net_init(struct net *net)
587 {
588 	struct sock *nfnl;
589 	struct netlink_kernel_cfg cfg = {
590 		.groups	= NFNLGRP_MAX,
591 		.input	= nfnetlink_rcv,
592 #ifdef CONFIG_MODULES
593 		.bind	= nfnetlink_bind,
594 #endif
595 	};
596 
597 	nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
598 	if (!nfnl)
599 		return -ENOMEM;
600 	net->nfnl_stash = nfnl;
601 	rcu_assign_pointer(net->nfnl, nfnl);
602 	return 0;
603 }
604 
605 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
606 {
607 	struct net *net;
608 
609 	list_for_each_entry(net, net_exit_list, exit_list)
610 		RCU_INIT_POINTER(net->nfnl, NULL);
611 	synchronize_net();
612 	list_for_each_entry(net, net_exit_list, exit_list)
613 		netlink_kernel_release(net->nfnl_stash);
614 }
615 
616 static struct pernet_operations nfnetlink_net_ops = {
617 	.init		= nfnetlink_net_init,
618 	.exit_batch	= nfnetlink_net_exit_batch,
619 };
620 
621 static int __init nfnetlink_init(void)
622 {
623 	int i;
624 
625 	for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
626 		BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
627 
628 	for (i=0; i<NFNL_SUBSYS_COUNT; i++)
629 		mutex_init(&table[i].mutex);
630 
631 	return register_pernet_subsys(&nfnetlink_net_ops);
632 }
633 
634 static void __exit nfnetlink_exit(void)
635 {
636 	unregister_pernet_subsys(&nfnetlink_net_ops);
637 }
638 module_init(nfnetlink_init);
639 module_exit(nfnetlink_exit);
640