xref: /openbmc/linux/net/netfilter/nfnetlink.c (revision 5f66f73b) 
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 			err = -EINVAL;
299 			break;
300 		}
301 		if (err == -EAGAIN)
302 			goto replay;
303 		return err;
304 	}
305 }
306 
307 struct nfnl_err {
308 	struct list_head	head;
309 	struct nlmsghdr		*nlh;
310 	int			err;
311 	struct netlink_ext_ack	extack;
312 };
313 
314 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
315 			const struct netlink_ext_ack *extack)
316 {
317 	struct nfnl_err *nfnl_err;
318 
319 	nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
320 	if (nfnl_err == NULL)
321 		return -ENOMEM;
322 
323 	nfnl_err->nlh = nlh;
324 	nfnl_err->err = err;
325 	nfnl_err->extack = *extack;
326 	list_add_tail(&nfnl_err->head, list);
327 
328 	return 0;
329 }
330 
331 static void nfnl_err_del(struct nfnl_err *nfnl_err)
332 {
333 	list_del(&nfnl_err->head);
334 	kfree(nfnl_err);
335 }
336 
337 static void nfnl_err_reset(struct list_head *err_list)
338 {
339 	struct nfnl_err *nfnl_err, *next;
340 
341 	list_for_each_entry_safe(nfnl_err, next, err_list, head)
342 		nfnl_err_del(nfnl_err);
343 }
344 
345 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
346 {
347 	struct nfnl_err *nfnl_err, *next;
348 
349 	list_for_each_entry_safe(nfnl_err, next, err_list, head) {
350 		netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
351 			    &nfnl_err->extack);
352 		nfnl_err_del(nfnl_err);
353 	}
354 }
355 
356 enum {
357 	NFNL_BATCH_FAILURE	= (1 << 0),
358 	NFNL_BATCH_DONE		= (1 << 1),
359 	NFNL_BATCH_REPLAY	= (1 << 2),
360 };
361 
362 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
363 				u16 subsys_id, u32 genid)
364 {
365 	struct sk_buff *oskb = skb;
366 	struct net *net = sock_net(skb->sk);
367 	const struct nfnetlink_subsystem *ss;
368 	const struct nfnl_callback *nc;
369 	struct netlink_ext_ack extack;
370 	LIST_HEAD(err_list);
371 	u32 status;
372 	int err;
373 
374 	if (subsys_id >= NFNL_SUBSYS_COUNT)
375 		return netlink_ack(skb, nlh, -EINVAL, NULL);
376 replay:
377 	status = 0;
378 replay_abort:
379 	skb = netlink_skb_clone(oskb, GFP_KERNEL);
380 	if (!skb)
381 		return netlink_ack(oskb, nlh, -ENOMEM, NULL);
382 
383 	nfnl_lock(subsys_id);
384 	ss = nfnl_dereference_protected(subsys_id);
385 	if (!ss) {
386 #ifdef CONFIG_MODULES
387 		nfnl_unlock(subsys_id);
388 		request_module("nfnetlink-subsys-%d", subsys_id);
389 		nfnl_lock(subsys_id);
390 		ss = nfnl_dereference_protected(subsys_id);
391 		if (!ss)
392 #endif
393 		{
394 			nfnl_unlock(subsys_id);
395 			netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
396 			return kfree_skb(skb);
397 		}
398 	}
399 
400 	if (!ss->valid_genid || !ss->commit || !ss->abort) {
401 		nfnl_unlock(subsys_id);
402 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
403 		return kfree_skb(skb);
404 	}
405 
406 	if (!try_module_get(ss->owner)) {
407 		nfnl_unlock(subsys_id);
408 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
409 		return kfree_skb(skb);
410 	}
411 
412 	if (!ss->valid_genid(net, genid)) {
413 		module_put(ss->owner);
414 		nfnl_unlock(subsys_id);
415 		netlink_ack(oskb, nlh, -ERESTART, NULL);
416 		return kfree_skb(skb);
417 	}
418 
419 	nfnl_unlock(subsys_id);
420 
421 	while (skb->len >= nlmsg_total_size(0)) {
422 		int msglen, type;
423 
424 		if (fatal_signal_pending(current)) {
425 			nfnl_err_reset(&err_list);
426 			err = -EINTR;
427 			status = NFNL_BATCH_FAILURE;
428 			goto done;
429 		}
430 
431 		memset(&extack, 0, sizeof(extack));
432 		nlh = nlmsg_hdr(skb);
433 		err = 0;
434 
435 		if (nlh->nlmsg_len < NLMSG_HDRLEN ||
436 		    skb->len < nlh->nlmsg_len ||
437 		    nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
438 			nfnl_err_reset(&err_list);
439 			status |= NFNL_BATCH_FAILURE;
440 			goto done;
441 		}
442 
443 		/* Only requests are handled by the kernel */
444 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
445 			err = -EINVAL;
446 			goto ack;
447 		}
448 
449 		type = nlh->nlmsg_type;
450 		if (type == NFNL_MSG_BATCH_BEGIN) {
451 			/* Malformed: Batch begin twice */
452 			nfnl_err_reset(&err_list);
453 			status |= NFNL_BATCH_FAILURE;
454 			goto done;
455 		} else if (type == NFNL_MSG_BATCH_END) {
456 			status |= NFNL_BATCH_DONE;
457 			goto done;
458 		} else if (type < NLMSG_MIN_TYPE) {
459 			err = -EINVAL;
460 			goto ack;
461 		}
462 
463 		/* We only accept a batch with messages for the same
464 		 * subsystem.
465 		 */
466 		if (NFNL_SUBSYS_ID(type) != subsys_id) {
467 			err = -EINVAL;
468 			goto ack;
469 		}
470 
471 		nc = nfnetlink_find_client(type, ss);
472 		if (!nc) {
473 			err = -EINVAL;
474 			goto ack;
475 		}
476 
477 		if (nc->type != NFNL_CB_BATCH) {
478 			err = -EINVAL;
479 			goto ack;
480 		}
481 
482 		{
483 			int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
484 			struct nfnl_net *nfnlnet = nfnl_pernet(net);
485 			struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
486 			struct nlattr *attr = (void *)nlh + min_len;
487 			u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
488 			int attrlen = nlh->nlmsg_len - min_len;
489 			struct nfnl_info info = {
490 				.net	= net,
491 				.sk	= nfnlnet->nfnl,
492 				.nlh	= nlh,
493 				.extack	= &extack,
494 			};
495 
496 			/* Sanity-check NFTA_MAX_ATTR */
497 			if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
498 				err = -ENOMEM;
499 				goto ack;
500 			}
501 
502 			err = nla_parse_deprecated(cda,
503 						   ss->cb[cb_id].attr_count,
504 						   attr, attrlen,
505 						   ss->cb[cb_id].policy, NULL);
506 			if (err < 0)
507 				goto ack;
508 
509 			err = nc->call(skb, &info, (const struct nlattr **)cda);
510 
511 			/* The lock was released to autoload some module, we
512 			 * have to abort and start from scratch using the
513 			 * original skb.
514 			 */
515 			if (err == -EAGAIN) {
516 				status |= NFNL_BATCH_REPLAY;
517 				goto done;
518 			}
519 		}
520 ack:
521 		if (nlh->nlmsg_flags & NLM_F_ACK || err) {
522 			/* Errors are delivered once the full batch has been
523 			 * processed, this avoids that the same error is
524 			 * reported several times when replaying the batch.
525 			 */
526 			if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
527 				/* We failed to enqueue an error, reset the
528 				 * list of errors and send OOM to userspace
529 				 * pointing to the batch header.
530 				 */
531 				nfnl_err_reset(&err_list);
532 				netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
533 					    NULL);
534 				status |= NFNL_BATCH_FAILURE;
535 				goto done;
536 			}
537 			/* We don't stop processing the batch on errors, thus,
538 			 * userspace gets all the errors that the batch
539 			 * triggers.
540 			 */
541 			if (err)
542 				status |= NFNL_BATCH_FAILURE;
543 		}
544 
545 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
546 		if (msglen > skb->len)
547 			msglen = skb->len;
548 		skb_pull(skb, msglen);
549 	}
550 done:
551 	if (status & NFNL_BATCH_REPLAY) {
552 		ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
553 		nfnl_err_reset(&err_list);
554 		kfree_skb(skb);
555 		module_put(ss->owner);
556 		goto replay;
557 	} else if (status == NFNL_BATCH_DONE) {
558 		err = ss->commit(net, oskb);
559 		if (err == -EAGAIN) {
560 			status |= NFNL_BATCH_REPLAY;
561 			goto done;
562 		} else if (err) {
563 			ss->abort(net, oskb, NFNL_ABORT_NONE);
564 			netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
565 		}
566 	} else {
567 		enum nfnl_abort_action abort_action;
568 
569 		if (status & NFNL_BATCH_FAILURE)
570 			abort_action = NFNL_ABORT_NONE;
571 		else
572 			abort_action = NFNL_ABORT_VALIDATE;
573 
574 		err = ss->abort(net, oskb, abort_action);
575 		if (err == -EAGAIN) {
576 			nfnl_err_reset(&err_list);
577 			kfree_skb(skb);
578 			module_put(ss->owner);
579 			status |= NFNL_BATCH_FAILURE;
580 			goto replay_abort;
581 		}
582 	}
583 	if (ss->cleanup)
584 		ss->cleanup(net);
585 
586 	nfnl_err_deliver(&err_list, oskb);
587 	kfree_skb(skb);
588 	module_put(ss->owner);
589 }
590 
591 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
592 	[NFNL_BATCH_GENID]	= { .type = NLA_U32 },
593 };
594 
595 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
596 {
597 	int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
598 	struct nlattr *attr = (void *)nlh + min_len;
599 	struct nlattr *cda[NFNL_BATCH_MAX + 1];
600 	int attrlen = nlh->nlmsg_len - min_len;
601 	struct nfgenmsg *nfgenmsg;
602 	int msglen, err;
603 	u32 gen_id = 0;
604 	u16 res_id;
605 
606 	msglen = NLMSG_ALIGN(nlh->nlmsg_len);
607 	if (msglen > skb->len)
608 		msglen = skb->len;
609 
610 	if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
611 		return;
612 
613 	err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
614 				   nfnl_batch_policy, NULL);
615 	if (err < 0) {
616 		netlink_ack(skb, nlh, err, NULL);
617 		return;
618 	}
619 	if (cda[NFNL_BATCH_GENID])
620 		gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
621 
622 	nfgenmsg = nlmsg_data(nlh);
623 	skb_pull(skb, msglen);
624 	/* Work around old nft using host byte order */
625 	if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
626 		res_id = NFNL_SUBSYS_NFTABLES;
627 	else
628 		res_id = ntohs(nfgenmsg->res_id);
629 
630 	nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
631 }
632 
633 static void nfnetlink_rcv(struct sk_buff *skb)
634 {
635 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
636 
637 	if (skb->len < NLMSG_HDRLEN ||
638 	    nlh->nlmsg_len < NLMSG_HDRLEN ||
639 	    skb->len < nlh->nlmsg_len)
640 		return;
641 
642 	if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
643 		netlink_ack(skb, nlh, -EPERM, NULL);
644 		return;
645 	}
646 
647 	if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
648 		nfnetlink_rcv_skb_batch(skb, nlh);
649 	else
650 		netlink_rcv_skb(skb, nfnetlink_rcv_msg);
651 }
652 
653 #ifdef CONFIG_MODULES
654 static int nfnetlink_bind(struct net *net, int group)
655 {
656 	const struct nfnetlink_subsystem *ss;
657 	int type;
658 
659 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
660 		return 0;
661 
662 	type = nfnl_group2type[group];
663 
664 	rcu_read_lock();
665 	ss = nfnetlink_get_subsys(type << 8);
666 	rcu_read_unlock();
667 	if (!ss)
668 		request_module_nowait("nfnetlink-subsys-%d", type);
669 	return 0;
670 }
671 #endif
672 
673 static int __net_init nfnetlink_net_init(struct net *net)
674 {
675 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
676 	struct netlink_kernel_cfg cfg = {
677 		.groups	= NFNLGRP_MAX,
678 		.input	= nfnetlink_rcv,
679 #ifdef CONFIG_MODULES
680 		.bind	= nfnetlink_bind,
681 #endif
682 	};
683 
684 	nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
685 	if (!nfnlnet->nfnl)
686 		return -ENOMEM;
687 	return 0;
688 }
689 
690 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
691 {
692 	struct nfnl_net *nfnlnet;
693 	struct net *net;
694 
695 	list_for_each_entry(net, net_exit_list, exit_list) {
696 		nfnlnet = nfnl_pernet(net);
697 
698 		netlink_kernel_release(nfnlnet->nfnl);
699 	}
700 }
701 
702 static struct pernet_operations nfnetlink_net_ops = {
703 	.init		= nfnetlink_net_init,
704 	.exit_batch	= nfnetlink_net_exit_batch,
705 	.id		= &nfnetlink_pernet_id,
706 	.size		= sizeof(struct nfnl_net),
707 };
708 
709 static int __init nfnetlink_init(void)
710 {
711 	int i;
712 
713 	for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
714 		BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
715 
716 	for (i=0; i<NFNL_SUBSYS_COUNT; i++)
717 		__mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
718 
719 	return register_pernet_subsys(&nfnetlink_net_ops);
720 }
721 
722 static void __exit nfnetlink_exit(void)
723 {
724 	unregister_pernet_subsys(&nfnetlink_net_ops);
725 }
726 module_init(nfnetlink_init);
727 module_exit(nfnetlink_exit);
728