xref: /openbmc/linux/net/netfilter/nfnetlink.c (revision 79e790ff) 
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 <net/netns/generic.h>
32 #include <linux/netfilter/nfnetlink.h>
33 
34 MODULE_LICENSE("GPL");
35 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
36 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
37 MODULE_DESCRIPTION("Netfilter messages via netlink socket");
38 
39 #define nfnl_dereference_protected(id) \
40 	rcu_dereference_protected(table[(id)].subsys, \
41 				  lockdep_nfnl_is_held((id)))
42 
43 #define NFNL_MAX_ATTR_COUNT	32
44 
45 static unsigned int nfnetlink_pernet_id __read_mostly;
46 
47 struct nfnl_net {
48 	struct sock *nfnl;
49 };
50 
51 static struct {
52 	struct mutex				mutex;
53 	const struct nfnetlink_subsystem __rcu	*subsys;
54 } table[NFNL_SUBSYS_COUNT];
55 
56 static struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT];
57 
58 static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = {
59 	[NFNL_SUBSYS_NONE] = "nfnl_subsys_none",
60 	[NFNL_SUBSYS_CTNETLINK] = "nfnl_subsys_ctnetlink",
61 	[NFNL_SUBSYS_CTNETLINK_EXP] = "nfnl_subsys_ctnetlink_exp",
62 	[NFNL_SUBSYS_QUEUE] = "nfnl_subsys_queue",
63 	[NFNL_SUBSYS_ULOG] = "nfnl_subsys_ulog",
64 	[NFNL_SUBSYS_OSF] = "nfnl_subsys_osf",
65 	[NFNL_SUBSYS_IPSET] = "nfnl_subsys_ipset",
66 	[NFNL_SUBSYS_ACCT] = "nfnl_subsys_acct",
67 	[NFNL_SUBSYS_CTNETLINK_TIMEOUT] = "nfnl_subsys_cttimeout",
68 	[NFNL_SUBSYS_CTHELPER] = "nfnl_subsys_cthelper",
69 	[NFNL_SUBSYS_NFTABLES] = "nfnl_subsys_nftables",
70 	[NFNL_SUBSYS_NFT_COMPAT] = "nfnl_subsys_nftcompat",
71 };
72 
73 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
74 	[NFNLGRP_CONNTRACK_NEW]		= NFNL_SUBSYS_CTNETLINK,
75 	[NFNLGRP_CONNTRACK_UPDATE]	= NFNL_SUBSYS_CTNETLINK,
76 	[NFNLGRP_CONNTRACK_DESTROY]	= NFNL_SUBSYS_CTNETLINK,
77 	[NFNLGRP_CONNTRACK_EXP_NEW]	= NFNL_SUBSYS_CTNETLINK_EXP,
78 	[NFNLGRP_CONNTRACK_EXP_UPDATE]	= NFNL_SUBSYS_CTNETLINK_EXP,
79 	[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
80 	[NFNLGRP_NFTABLES]		= NFNL_SUBSYS_NFTABLES,
81 	[NFNLGRP_ACCT_QUOTA]		= NFNL_SUBSYS_ACCT,
82 	[NFNLGRP_NFTRACE]		= NFNL_SUBSYS_NFTABLES,
83 };
84 
85 static struct nfnl_net *nfnl_pernet(struct net *net)
86 {
87 	return net_generic(net, nfnetlink_pernet_id);
88 }
89 
90 void nfnl_lock(__u8 subsys_id)
91 {
92 	mutex_lock(&table[subsys_id].mutex);
93 }
94 EXPORT_SYMBOL_GPL(nfnl_lock);
95 
96 void nfnl_unlock(__u8 subsys_id)
97 {
98 	mutex_unlock(&table[subsys_id].mutex);
99 }
100 EXPORT_SYMBOL_GPL(nfnl_unlock);
101 
102 #ifdef CONFIG_PROVE_LOCKING
103 bool lockdep_nfnl_is_held(u8 subsys_id)
104 {
105 	return lockdep_is_held(&table[subsys_id].mutex);
106 }
107 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
108 #endif
109 
110 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
111 {
112 	u8 cb_id;
113 
114 	/* Sanity-check attr_count size to avoid stack buffer overflow. */
115 	for (cb_id = 0; cb_id < n->cb_count; cb_id++)
116 		if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
117 			return -EINVAL;
118 
119 	nfnl_lock(n->subsys_id);
120 	if (table[n->subsys_id].subsys) {
121 		nfnl_unlock(n->subsys_id);
122 		return -EBUSY;
123 	}
124 	rcu_assign_pointer(table[n->subsys_id].subsys, n);
125 	nfnl_unlock(n->subsys_id);
126 
127 	return 0;
128 }
129 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
130 
131 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
132 {
133 	nfnl_lock(n->subsys_id);
134 	table[n->subsys_id].subsys = NULL;
135 	nfnl_unlock(n->subsys_id);
136 	synchronize_rcu();
137 	return 0;
138 }
139 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
140 
141 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
142 {
143 	u8 subsys_id = NFNL_SUBSYS_ID(type);
144 
145 	if (subsys_id >= NFNL_SUBSYS_COUNT)
146 		return NULL;
147 
148 	return rcu_dereference(table[subsys_id].subsys);
149 }
150 
151 static inline const struct nfnl_callback *
152 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
153 {
154 	u8 cb_id = NFNL_MSG_TYPE(type);
155 
156 	if (cb_id >= ss->cb_count)
157 		return NULL;
158 
159 	return &ss->cb[cb_id];
160 }
161 
162 int nfnetlink_has_listeners(struct net *net, unsigned int group)
163 {
164 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
165 
166 	return netlink_has_listeners(nfnlnet->nfnl, group);
167 }
168 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
169 
170 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
171 		   unsigned int group, int echo, gfp_t flags)
172 {
173 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
174 
175 	return nlmsg_notify(nfnlnet->nfnl, skb, portid, group, echo, flags);
176 }
177 EXPORT_SYMBOL_GPL(nfnetlink_send);
178 
179 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
180 {
181 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
182 
183 	return netlink_set_err(nfnlnet->nfnl, portid, group, error);
184 }
185 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
186 
187 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
188 {
189 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
190 	int err;
191 
192 	err = nlmsg_unicast(nfnlnet->nfnl, skb, portid);
193 	if (err == -EAGAIN)
194 		err = -ENOBUFS;
195 
196 	return err;
197 }
198 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
199 
200 void nfnetlink_broadcast(struct net *net, struct sk_buff *skb, __u32 portid,
201 			 __u32 group, gfp_t allocation)
202 {
203 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
204 
205 	netlink_broadcast(nfnlnet->nfnl, skb, portid, group, allocation);
206 }
207 EXPORT_SYMBOL_GPL(nfnetlink_broadcast);
208 
209 /* Process one complete nfnetlink message. */
210 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
211 			     struct netlink_ext_ack *extack)
212 {
213 	struct net *net = sock_net(skb->sk);
214 	const struct nfnl_callback *nc;
215 	const struct nfnetlink_subsystem *ss;
216 	int type, err;
217 
218 	/* All the messages must at least contain nfgenmsg */
219 	if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
220 		return 0;
221 
222 	type = nlh->nlmsg_type;
223 replay:
224 	rcu_read_lock();
225 
226 	ss = nfnetlink_get_subsys(type);
227 	if (!ss) {
228 #ifdef CONFIG_MODULES
229 		rcu_read_unlock();
230 		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
231 		rcu_read_lock();
232 		ss = nfnetlink_get_subsys(type);
233 		if (!ss)
234 #endif
235 		{
236 			rcu_read_unlock();
237 			return -EINVAL;
238 		}
239 	}
240 
241 	nc = nfnetlink_find_client(type, ss);
242 	if (!nc) {
243 		rcu_read_unlock();
244 		return -EINVAL;
245 	}
246 
247 	{
248 		int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
249 		struct nfnl_net *nfnlnet = nfnl_pernet(net);
250 		u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
251 		struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
252 		struct nlattr *attr = (void *)nlh + min_len;
253 		int attrlen = nlh->nlmsg_len - min_len;
254 		__u8 subsys_id = NFNL_SUBSYS_ID(type);
255 		struct nfnl_info info = {
256 			.net	= net,
257 			.sk	= nfnlnet->nfnl,
258 			.nlh	= nlh,
259 			.extack	= extack,
260 		};
261 
262 		/* Sanity-check NFNL_MAX_ATTR_COUNT */
263 		if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
264 			rcu_read_unlock();
265 			return -ENOMEM;
266 		}
267 
268 		err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
269 					   attr, attrlen,
270 					   ss->cb[cb_id].policy, extack);
271 		if (err < 0) {
272 			rcu_read_unlock();
273 			return err;
274 		}
275 
276 		if (!nc->call) {
277 			rcu_read_unlock();
278 			return -EINVAL;
279 		}
280 
281 		switch (nc->type) {
282 		case NFNL_CB_RCU:
283 			err = nc->call(skb, &info, (const struct nlattr **)cda);
284 			rcu_read_unlock();
285 			break;
286 		case NFNL_CB_MUTEX:
287 			rcu_read_unlock();
288 			nfnl_lock(subsys_id);
289 			if (nfnl_dereference_protected(subsys_id) != ss ||
290 			    nfnetlink_find_client(type, ss) != nc) {
291 				err = -EAGAIN;
292 				break;
293 			}
294 			err = nc->call(skb, &info, (const struct nlattr **)cda);
295 			nfnl_unlock(subsys_id);
296 			break;
297 		default:
298 			rcu_read_unlock();
299 			err = -EINVAL;
300 			break;
301 		}
302 		if (err == -EAGAIN)
303 			goto replay;
304 		return err;
305 	}
306 }
307 
308 struct nfnl_err {
309 	struct list_head	head;
310 	struct nlmsghdr		*nlh;
311 	int			err;
312 	struct netlink_ext_ack	extack;
313 };
314 
315 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
316 			const struct netlink_ext_ack *extack)
317 {
318 	struct nfnl_err *nfnl_err;
319 
320 	nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
321 	if (nfnl_err == NULL)
322 		return -ENOMEM;
323 
324 	nfnl_err->nlh = nlh;
325 	nfnl_err->err = err;
326 	nfnl_err->extack = *extack;
327 	list_add_tail(&nfnl_err->head, list);
328 
329 	return 0;
330 }
331 
332 static void nfnl_err_del(struct nfnl_err *nfnl_err)
333 {
334 	list_del(&nfnl_err->head);
335 	kfree(nfnl_err);
336 }
337 
338 static void nfnl_err_reset(struct list_head *err_list)
339 {
340 	struct nfnl_err *nfnl_err, *next;
341 
342 	list_for_each_entry_safe(nfnl_err, next, err_list, head)
343 		nfnl_err_del(nfnl_err);
344 }
345 
346 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
347 {
348 	struct nfnl_err *nfnl_err, *next;
349 
350 	list_for_each_entry_safe(nfnl_err, next, err_list, head) {
351 		netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
352 			    &nfnl_err->extack);
353 		nfnl_err_del(nfnl_err);
354 	}
355 }
356 
357 enum {
358 	NFNL_BATCH_FAILURE	= (1 << 0),
359 	NFNL_BATCH_DONE		= (1 << 1),
360 	NFNL_BATCH_REPLAY	= (1 << 2),
361 };
362 
363 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
364 				u16 subsys_id, u32 genid)
365 {
366 	struct sk_buff *oskb = skb;
367 	struct net *net = sock_net(skb->sk);
368 	const struct nfnetlink_subsystem *ss;
369 	const struct nfnl_callback *nc;
370 	struct netlink_ext_ack extack;
371 	LIST_HEAD(err_list);
372 	u32 status;
373 	int err;
374 
375 	if (subsys_id >= NFNL_SUBSYS_COUNT)
376 		return netlink_ack(skb, nlh, -EINVAL, NULL);
377 replay:
378 	status = 0;
379 replay_abort:
380 	skb = netlink_skb_clone(oskb, GFP_KERNEL);
381 	if (!skb)
382 		return netlink_ack(oskb, nlh, -ENOMEM, NULL);
383 
384 	nfnl_lock(subsys_id);
385 	ss = nfnl_dereference_protected(subsys_id);
386 	if (!ss) {
387 #ifdef CONFIG_MODULES
388 		nfnl_unlock(subsys_id);
389 		request_module("nfnetlink-subsys-%d", subsys_id);
390 		nfnl_lock(subsys_id);
391 		ss = nfnl_dereference_protected(subsys_id);
392 		if (!ss)
393 #endif
394 		{
395 			nfnl_unlock(subsys_id);
396 			netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
397 			return kfree_skb(skb);
398 		}
399 	}
400 
401 	if (!ss->valid_genid || !ss->commit || !ss->abort) {
402 		nfnl_unlock(subsys_id);
403 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
404 		return kfree_skb(skb);
405 	}
406 
407 	if (!try_module_get(ss->owner)) {
408 		nfnl_unlock(subsys_id);
409 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
410 		return kfree_skb(skb);
411 	}
412 
413 	if (!ss->valid_genid(net, genid)) {
414 		module_put(ss->owner);
415 		nfnl_unlock(subsys_id);
416 		netlink_ack(oskb, nlh, -ERESTART, NULL);
417 		return kfree_skb(skb);
418 	}
419 
420 	nfnl_unlock(subsys_id);
421 
422 	while (skb->len >= nlmsg_total_size(0)) {
423 		int msglen, type;
424 
425 		if (fatal_signal_pending(current)) {
426 			nfnl_err_reset(&err_list);
427 			err = -EINTR;
428 			status = NFNL_BATCH_FAILURE;
429 			goto done;
430 		}
431 
432 		memset(&extack, 0, sizeof(extack));
433 		nlh = nlmsg_hdr(skb);
434 		err = 0;
435 
436 		if (nlh->nlmsg_len < NLMSG_HDRLEN ||
437 		    skb->len < nlh->nlmsg_len ||
438 		    nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
439 			nfnl_err_reset(&err_list);
440 			status |= NFNL_BATCH_FAILURE;
441 			goto done;
442 		}
443 
444 		/* Only requests are handled by the kernel */
445 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
446 			err = -EINVAL;
447 			goto ack;
448 		}
449 
450 		type = nlh->nlmsg_type;
451 		if (type == NFNL_MSG_BATCH_BEGIN) {
452 			/* Malformed: Batch begin twice */
453 			nfnl_err_reset(&err_list);
454 			status |= NFNL_BATCH_FAILURE;
455 			goto done;
456 		} else if (type == NFNL_MSG_BATCH_END) {
457 			status |= NFNL_BATCH_DONE;
458 			goto done;
459 		} else if (type < NLMSG_MIN_TYPE) {
460 			err = -EINVAL;
461 			goto ack;
462 		}
463 
464 		/* We only accept a batch with messages for the same
465 		 * subsystem.
466 		 */
467 		if (NFNL_SUBSYS_ID(type) != subsys_id) {
468 			err = -EINVAL;
469 			goto ack;
470 		}
471 
472 		nc = nfnetlink_find_client(type, ss);
473 		if (!nc) {
474 			err = -EINVAL;
475 			goto ack;
476 		}
477 
478 		if (nc->type != NFNL_CB_BATCH) {
479 			err = -EINVAL;
480 			goto ack;
481 		}
482 
483 		{
484 			int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
485 			struct nfnl_net *nfnlnet = nfnl_pernet(net);
486 			struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
487 			struct nlattr *attr = (void *)nlh + min_len;
488 			u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
489 			int attrlen = nlh->nlmsg_len - min_len;
490 			struct nfnl_info info = {
491 				.net	= net,
492 				.sk	= nfnlnet->nfnl,
493 				.nlh	= nlh,
494 				.extack	= &extack,
495 			};
496 
497 			/* Sanity-check NFTA_MAX_ATTR */
498 			if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
499 				err = -ENOMEM;
500 				goto ack;
501 			}
502 
503 			err = nla_parse_deprecated(cda,
504 						   ss->cb[cb_id].attr_count,
505 						   attr, attrlen,
506 						   ss->cb[cb_id].policy, NULL);
507 			if (err < 0)
508 				goto ack;
509 
510 			err = nc->call(skb, &info, (const struct nlattr **)cda);
511 
512 			/* The lock was released to autoload some module, we
513 			 * have to abort and start from scratch using the
514 			 * original skb.
515 			 */
516 			if (err == -EAGAIN) {
517 				status |= NFNL_BATCH_REPLAY;
518 				goto done;
519 			}
520 		}
521 ack:
522 		if (nlh->nlmsg_flags & NLM_F_ACK || err) {
523 			/* Errors are delivered once the full batch has been
524 			 * processed, this avoids that the same error is
525 			 * reported several times when replaying the batch.
526 			 */
527 			if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
528 				/* We failed to enqueue an error, reset the
529 				 * list of errors and send OOM to userspace
530 				 * pointing to the batch header.
531 				 */
532 				nfnl_err_reset(&err_list);
533 				netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
534 					    NULL);
535 				status |= NFNL_BATCH_FAILURE;
536 				goto done;
537 			}
538 			/* We don't stop processing the batch on errors, thus,
539 			 * userspace gets all the errors that the batch
540 			 * triggers.
541 			 */
542 			if (err)
543 				status |= NFNL_BATCH_FAILURE;
544 		}
545 
546 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
547 		if (msglen > skb->len)
548 			msglen = skb->len;
549 		skb_pull(skb, msglen);
550 	}
551 done:
552 	if (status & NFNL_BATCH_REPLAY) {
553 		ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
554 		nfnl_err_reset(&err_list);
555 		kfree_skb(skb);
556 		module_put(ss->owner);
557 		goto replay;
558 	} else if (status == NFNL_BATCH_DONE) {
559 		err = ss->commit(net, oskb);
560 		if (err == -EAGAIN) {
561 			status |= NFNL_BATCH_REPLAY;
562 			goto done;
563 		} else if (err) {
564 			ss->abort(net, oskb, NFNL_ABORT_NONE);
565 			netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
566 		}
567 	} else {
568 		enum nfnl_abort_action abort_action;
569 
570 		if (status & NFNL_BATCH_FAILURE)
571 			abort_action = NFNL_ABORT_NONE;
572 		else
573 			abort_action = NFNL_ABORT_VALIDATE;
574 
575 		err = ss->abort(net, oskb, abort_action);
576 		if (err == -EAGAIN) {
577 			nfnl_err_reset(&err_list);
578 			kfree_skb(skb);
579 			module_put(ss->owner);
580 			status |= NFNL_BATCH_FAILURE;
581 			goto replay_abort;
582 		}
583 	}
584 	if (ss->cleanup)
585 		ss->cleanup(net);
586 
587 	nfnl_err_deliver(&err_list, oskb);
588 	kfree_skb(skb);
589 	module_put(ss->owner);
590 }
591 
592 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
593 	[NFNL_BATCH_GENID]	= { .type = NLA_U32 },
594 };
595 
596 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
597 {
598 	int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
599 	struct nlattr *attr = (void *)nlh + min_len;
600 	struct nlattr *cda[NFNL_BATCH_MAX + 1];
601 	int attrlen = nlh->nlmsg_len - min_len;
602 	struct nfgenmsg *nfgenmsg;
603 	int msglen, err;
604 	u32 gen_id = 0;
605 	u16 res_id;
606 
607 	msglen = NLMSG_ALIGN(nlh->nlmsg_len);
608 	if (msglen > skb->len)
609 		msglen = skb->len;
610 
611 	if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
612 		return;
613 
614 	err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
615 				   nfnl_batch_policy, NULL);
616 	if (err < 0) {
617 		netlink_ack(skb, nlh, err, NULL);
618 		return;
619 	}
620 	if (cda[NFNL_BATCH_GENID])
621 		gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
622 
623 	nfgenmsg = nlmsg_data(nlh);
624 	skb_pull(skb, msglen);
625 	/* Work around old nft using host byte order */
626 	if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
627 		res_id = NFNL_SUBSYS_NFTABLES;
628 	else
629 		res_id = ntohs(nfgenmsg->res_id);
630 
631 	nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
632 }
633 
634 static void nfnetlink_rcv(struct sk_buff *skb)
635 {
636 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
637 
638 	if (skb->len < NLMSG_HDRLEN ||
639 	    nlh->nlmsg_len < NLMSG_HDRLEN ||
640 	    skb->len < nlh->nlmsg_len)
641 		return;
642 
643 	if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
644 		netlink_ack(skb, nlh, -EPERM, NULL);
645 		return;
646 	}
647 
648 	if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
649 		nfnetlink_rcv_skb_batch(skb, nlh);
650 	else
651 		netlink_rcv_skb(skb, nfnetlink_rcv_msg);
652 }
653 
654 #ifdef CONFIG_MODULES
655 static int nfnetlink_bind(struct net *net, int group)
656 {
657 	const struct nfnetlink_subsystem *ss;
658 	int type;
659 
660 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
661 		return 0;
662 
663 	type = nfnl_group2type[group];
664 
665 	rcu_read_lock();
666 	ss = nfnetlink_get_subsys(type << 8);
667 	rcu_read_unlock();
668 	if (!ss)
669 		request_module_nowait("nfnetlink-subsys-%d", type);
670 	return 0;
671 }
672 #endif
673 
674 static int __net_init nfnetlink_net_init(struct net *net)
675 {
676 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
677 	struct netlink_kernel_cfg cfg = {
678 		.groups	= NFNLGRP_MAX,
679 		.input	= nfnetlink_rcv,
680 #ifdef CONFIG_MODULES
681 		.bind	= nfnetlink_bind,
682 #endif
683 	};
684 
685 	nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
686 	if (!nfnlnet->nfnl)
687 		return -ENOMEM;
688 	return 0;
689 }
690 
691 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
692 {
693 	struct nfnl_net *nfnlnet;
694 	struct net *net;
695 
696 	list_for_each_entry(net, net_exit_list, exit_list) {
697 		nfnlnet = nfnl_pernet(net);
698 
699 		netlink_kernel_release(nfnlnet->nfnl);
700 	}
701 }
702 
703 static struct pernet_operations nfnetlink_net_ops = {
704 	.init		= nfnetlink_net_init,
705 	.exit_batch	= nfnetlink_net_exit_batch,
706 	.id		= &nfnetlink_pernet_id,
707 	.size		= sizeof(struct nfnl_net),
708 };
709 
710 static int __init nfnetlink_init(void)
711 {
712 	int i;
713 
714 	for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
715 		BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
716 
717 	for (i=0; i<NFNL_SUBSYS_COUNT; i++)
718 		__mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
719 
720 	return register_pernet_subsys(&nfnetlink_net_ops);
721 }
722 
723 static void __exit nfnetlink_exit(void)
724 {
725 	unregister_pernet_subsys(&nfnetlink_net_ops);
726 }
727 module_init(nfnetlink_init);
728 module_exit(nfnetlink_exit);
729