xref: /openbmc/linux/net/netfilter/nfnetlink.c (revision 7fc96d71) 
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 	[NFNL_SUBSYS_HOOK] = "nfnl_subsys_hook",
72 };
73 
74 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
75 	[NFNLGRP_CONNTRACK_NEW]		= NFNL_SUBSYS_CTNETLINK,
76 	[NFNLGRP_CONNTRACK_UPDATE]	= NFNL_SUBSYS_CTNETLINK,
77 	[NFNLGRP_CONNTRACK_DESTROY]	= NFNL_SUBSYS_CTNETLINK,
78 	[NFNLGRP_CONNTRACK_EXP_NEW]	= NFNL_SUBSYS_CTNETLINK_EXP,
79 	[NFNLGRP_CONNTRACK_EXP_UPDATE]	= NFNL_SUBSYS_CTNETLINK_EXP,
80 	[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
81 	[NFNLGRP_NFTABLES]		= NFNL_SUBSYS_NFTABLES,
82 	[NFNLGRP_ACCT_QUOTA]		= NFNL_SUBSYS_ACCT,
83 	[NFNLGRP_NFTRACE]		= NFNL_SUBSYS_NFTABLES,
84 };
85 
86 static struct nfnl_net *nfnl_pernet(struct net *net)
87 {
88 	return net_generic(net, nfnetlink_pernet_id);
89 }
90 
91 void nfnl_lock(__u8 subsys_id)
92 {
93 	mutex_lock(&table[subsys_id].mutex);
94 }
95 EXPORT_SYMBOL_GPL(nfnl_lock);
96 
97 void nfnl_unlock(__u8 subsys_id)
98 {
99 	mutex_unlock(&table[subsys_id].mutex);
100 }
101 EXPORT_SYMBOL_GPL(nfnl_unlock);
102 
103 #ifdef CONFIG_PROVE_LOCKING
104 bool lockdep_nfnl_is_held(u8 subsys_id)
105 {
106 	return lockdep_is_held(&table[subsys_id].mutex);
107 }
108 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
109 #endif
110 
111 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
112 {
113 	u8 cb_id;
114 
115 	/* Sanity-check attr_count size to avoid stack buffer overflow. */
116 	for (cb_id = 0; cb_id < n->cb_count; cb_id++)
117 		if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
118 			return -EINVAL;
119 
120 	nfnl_lock(n->subsys_id);
121 	if (table[n->subsys_id].subsys) {
122 		nfnl_unlock(n->subsys_id);
123 		return -EBUSY;
124 	}
125 	rcu_assign_pointer(table[n->subsys_id].subsys, n);
126 	nfnl_unlock(n->subsys_id);
127 
128 	return 0;
129 }
130 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
131 
132 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
133 {
134 	nfnl_lock(n->subsys_id);
135 	table[n->subsys_id].subsys = NULL;
136 	nfnl_unlock(n->subsys_id);
137 	synchronize_rcu();
138 	return 0;
139 }
140 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
141 
142 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
143 {
144 	u8 subsys_id = NFNL_SUBSYS_ID(type);
145 
146 	if (subsys_id >= NFNL_SUBSYS_COUNT)
147 		return NULL;
148 
149 	return rcu_dereference(table[subsys_id].subsys);
150 }
151 
152 static inline const struct nfnl_callback *
153 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
154 {
155 	u8 cb_id = NFNL_MSG_TYPE(type);
156 
157 	if (cb_id >= ss->cb_count)
158 		return NULL;
159 
160 	return &ss->cb[cb_id];
161 }
162 
163 int nfnetlink_has_listeners(struct net *net, unsigned int group)
164 {
165 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
166 
167 	return netlink_has_listeners(nfnlnet->nfnl, group);
168 }
169 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
170 
171 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
172 		   unsigned int group, int echo, gfp_t flags)
173 {
174 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
175 
176 	return nlmsg_notify(nfnlnet->nfnl, skb, portid, group, echo, flags);
177 }
178 EXPORT_SYMBOL_GPL(nfnetlink_send);
179 
180 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
181 {
182 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
183 
184 	return netlink_set_err(nfnlnet->nfnl, portid, group, error);
185 }
186 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
187 
188 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
189 {
190 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
191 	int err;
192 
193 	err = nlmsg_unicast(nfnlnet->nfnl, skb, portid);
194 	if (err == -EAGAIN)
195 		err = -ENOBUFS;
196 
197 	return err;
198 }
199 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
200 
201 void nfnetlink_broadcast(struct net *net, struct sk_buff *skb, __u32 portid,
202 			 __u32 group, gfp_t allocation)
203 {
204 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
205 
206 	netlink_broadcast(nfnlnet->nfnl, skb, portid, group, allocation);
207 }
208 EXPORT_SYMBOL_GPL(nfnetlink_broadcast);
209 
210 /* Process one complete nfnetlink message. */
211 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
212 			     struct netlink_ext_ack *extack)
213 {
214 	struct net *net = sock_net(skb->sk);
215 	const struct nfnl_callback *nc;
216 	const struct nfnetlink_subsystem *ss;
217 	int type, err;
218 
219 	/* All the messages must at least contain nfgenmsg */
220 	if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
221 		return 0;
222 
223 	type = nlh->nlmsg_type;
224 replay:
225 	rcu_read_lock();
226 
227 	ss = nfnetlink_get_subsys(type);
228 	if (!ss) {
229 #ifdef CONFIG_MODULES
230 		rcu_read_unlock();
231 		request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
232 		rcu_read_lock();
233 		ss = nfnetlink_get_subsys(type);
234 		if (!ss)
235 #endif
236 		{
237 			rcu_read_unlock();
238 			return -EINVAL;
239 		}
240 	}
241 
242 	nc = nfnetlink_find_client(type, ss);
243 	if (!nc) {
244 		rcu_read_unlock();
245 		return -EINVAL;
246 	}
247 
248 	{
249 		int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
250 		struct nfnl_net *nfnlnet = nfnl_pernet(net);
251 		u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
252 		struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
253 		struct nlattr *attr = (void *)nlh + min_len;
254 		int attrlen = nlh->nlmsg_len - min_len;
255 		__u8 subsys_id = NFNL_SUBSYS_ID(type);
256 		struct nfnl_info info = {
257 			.net	= net,
258 			.sk	= nfnlnet->nfnl,
259 			.nlh	= nlh,
260 			.nfmsg	= nlmsg_data(nlh),
261 			.extack	= extack,
262 		};
263 
264 		/* Sanity-check NFNL_MAX_ATTR_COUNT */
265 		if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
266 			rcu_read_unlock();
267 			return -ENOMEM;
268 		}
269 
270 		err = nla_parse_deprecated(cda, ss->cb[cb_id].attr_count,
271 					   attr, attrlen,
272 					   ss->cb[cb_id].policy, extack);
273 		if (err < 0) {
274 			rcu_read_unlock();
275 			return err;
276 		}
277 
278 		if (!nc->call) {
279 			rcu_read_unlock();
280 			return -EINVAL;
281 		}
282 
283 		switch (nc->type) {
284 		case NFNL_CB_RCU:
285 			err = nc->call(skb, &info, (const struct nlattr **)cda);
286 			rcu_read_unlock();
287 			break;
288 		case NFNL_CB_MUTEX:
289 			rcu_read_unlock();
290 			nfnl_lock(subsys_id);
291 			if (nfnl_dereference_protected(subsys_id) != ss ||
292 			    nfnetlink_find_client(type, ss) != nc) {
293 				err = -EAGAIN;
294 				break;
295 			}
296 			err = nc->call(skb, &info, (const struct nlattr **)cda);
297 			nfnl_unlock(subsys_id);
298 			break;
299 		default:
300 			rcu_read_unlock();
301 			err = -EINVAL;
302 			break;
303 		}
304 		if (err == -EAGAIN)
305 			goto replay;
306 		return err;
307 	}
308 }
309 
310 struct nfnl_err {
311 	struct list_head	head;
312 	struct nlmsghdr		*nlh;
313 	int			err;
314 	struct netlink_ext_ack	extack;
315 };
316 
317 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
318 			const struct netlink_ext_ack *extack)
319 {
320 	struct nfnl_err *nfnl_err;
321 
322 	nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
323 	if (nfnl_err == NULL)
324 		return -ENOMEM;
325 
326 	nfnl_err->nlh = nlh;
327 	nfnl_err->err = err;
328 	nfnl_err->extack = *extack;
329 	list_add_tail(&nfnl_err->head, list);
330 
331 	return 0;
332 }
333 
334 static void nfnl_err_del(struct nfnl_err *nfnl_err)
335 {
336 	list_del(&nfnl_err->head);
337 	kfree(nfnl_err);
338 }
339 
340 static void nfnl_err_reset(struct list_head *err_list)
341 {
342 	struct nfnl_err *nfnl_err, *next;
343 
344 	list_for_each_entry_safe(nfnl_err, next, err_list, head)
345 		nfnl_err_del(nfnl_err);
346 }
347 
348 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
349 {
350 	struct nfnl_err *nfnl_err, *next;
351 
352 	list_for_each_entry_safe(nfnl_err, next, err_list, head) {
353 		netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
354 			    &nfnl_err->extack);
355 		nfnl_err_del(nfnl_err);
356 	}
357 }
358 
359 enum {
360 	NFNL_BATCH_FAILURE	= (1 << 0),
361 	NFNL_BATCH_DONE		= (1 << 1),
362 	NFNL_BATCH_REPLAY	= (1 << 2),
363 };
364 
365 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
366 				u16 subsys_id, u32 genid)
367 {
368 	struct sk_buff *oskb = skb;
369 	struct net *net = sock_net(skb->sk);
370 	const struct nfnetlink_subsystem *ss;
371 	const struct nfnl_callback *nc;
372 	struct netlink_ext_ack extack;
373 	LIST_HEAD(err_list);
374 	u32 status;
375 	int err;
376 
377 	if (subsys_id >= NFNL_SUBSYS_COUNT)
378 		return netlink_ack(skb, nlh, -EINVAL, NULL);
379 replay:
380 	status = 0;
381 replay_abort:
382 	skb = netlink_skb_clone(oskb, GFP_KERNEL);
383 	if (!skb)
384 		return netlink_ack(oskb, nlh, -ENOMEM, NULL);
385 
386 	nfnl_lock(subsys_id);
387 	ss = nfnl_dereference_protected(subsys_id);
388 	if (!ss) {
389 #ifdef CONFIG_MODULES
390 		nfnl_unlock(subsys_id);
391 		request_module("nfnetlink-subsys-%d", subsys_id);
392 		nfnl_lock(subsys_id);
393 		ss = nfnl_dereference_protected(subsys_id);
394 		if (!ss)
395 #endif
396 		{
397 			nfnl_unlock(subsys_id);
398 			netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
399 			return kfree_skb(skb);
400 		}
401 	}
402 
403 	if (!ss->valid_genid || !ss->commit || !ss->abort) {
404 		nfnl_unlock(subsys_id);
405 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
406 		return kfree_skb(skb);
407 	}
408 
409 	if (!try_module_get(ss->owner)) {
410 		nfnl_unlock(subsys_id);
411 		netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
412 		return kfree_skb(skb);
413 	}
414 
415 	if (!ss->valid_genid(net, genid)) {
416 		module_put(ss->owner);
417 		nfnl_unlock(subsys_id);
418 		netlink_ack(oskb, nlh, -ERESTART, NULL);
419 		return kfree_skb(skb);
420 	}
421 
422 	nfnl_unlock(subsys_id);
423 
424 	while (skb->len >= nlmsg_total_size(0)) {
425 		int msglen, type;
426 
427 		if (fatal_signal_pending(current)) {
428 			nfnl_err_reset(&err_list);
429 			err = -EINTR;
430 			status = NFNL_BATCH_FAILURE;
431 			goto done;
432 		}
433 
434 		memset(&extack, 0, sizeof(extack));
435 		nlh = nlmsg_hdr(skb);
436 		err = 0;
437 
438 		if (nlh->nlmsg_len < NLMSG_HDRLEN ||
439 		    skb->len < nlh->nlmsg_len ||
440 		    nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
441 			nfnl_err_reset(&err_list);
442 			status |= NFNL_BATCH_FAILURE;
443 			goto done;
444 		}
445 
446 		/* Only requests are handled by the kernel */
447 		if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
448 			err = -EINVAL;
449 			goto ack;
450 		}
451 
452 		type = nlh->nlmsg_type;
453 		if (type == NFNL_MSG_BATCH_BEGIN) {
454 			/* Malformed: Batch begin twice */
455 			nfnl_err_reset(&err_list);
456 			status |= NFNL_BATCH_FAILURE;
457 			goto done;
458 		} else if (type == NFNL_MSG_BATCH_END) {
459 			status |= NFNL_BATCH_DONE;
460 			goto done;
461 		} else if (type < NLMSG_MIN_TYPE) {
462 			err = -EINVAL;
463 			goto ack;
464 		}
465 
466 		/* We only accept a batch with messages for the same
467 		 * subsystem.
468 		 */
469 		if (NFNL_SUBSYS_ID(type) != subsys_id) {
470 			err = -EINVAL;
471 			goto ack;
472 		}
473 
474 		nc = nfnetlink_find_client(type, ss);
475 		if (!nc) {
476 			err = -EINVAL;
477 			goto ack;
478 		}
479 
480 		if (nc->type != NFNL_CB_BATCH) {
481 			err = -EINVAL;
482 			goto ack;
483 		}
484 
485 		{
486 			int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
487 			struct nfnl_net *nfnlnet = nfnl_pernet(net);
488 			struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
489 			struct nlattr *attr = (void *)nlh + min_len;
490 			u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
491 			int attrlen = nlh->nlmsg_len - min_len;
492 			struct nfnl_info info = {
493 				.net	= net,
494 				.sk	= nfnlnet->nfnl,
495 				.nlh	= nlh,
496 				.nfmsg	= nlmsg_data(nlh),
497 				.extack	= &extack,
498 			};
499 
500 			/* Sanity-check NFTA_MAX_ATTR */
501 			if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
502 				err = -ENOMEM;
503 				goto ack;
504 			}
505 
506 			err = nla_parse_deprecated(cda,
507 						   ss->cb[cb_id].attr_count,
508 						   attr, attrlen,
509 						   ss->cb[cb_id].policy, NULL);
510 			if (err < 0)
511 				goto ack;
512 
513 			err = nc->call(skb, &info, (const struct nlattr **)cda);
514 
515 			/* The lock was released to autoload some module, we
516 			 * have to abort and start from scratch using the
517 			 * original skb.
518 			 */
519 			if (err == -EAGAIN) {
520 				status |= NFNL_BATCH_REPLAY;
521 				goto done;
522 			}
523 		}
524 ack:
525 		if (nlh->nlmsg_flags & NLM_F_ACK || err) {
526 			/* Errors are delivered once the full batch has been
527 			 * processed, this avoids that the same error is
528 			 * reported several times when replaying the batch.
529 			 */
530 			if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
531 				/* We failed to enqueue an error, reset the
532 				 * list of errors and send OOM to userspace
533 				 * pointing to the batch header.
534 				 */
535 				nfnl_err_reset(&err_list);
536 				netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
537 					    NULL);
538 				status |= NFNL_BATCH_FAILURE;
539 				goto done;
540 			}
541 			/* We don't stop processing the batch on errors, thus,
542 			 * userspace gets all the errors that the batch
543 			 * triggers.
544 			 */
545 			if (err)
546 				status |= NFNL_BATCH_FAILURE;
547 		}
548 
549 		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
550 		if (msglen > skb->len)
551 			msglen = skb->len;
552 		skb_pull(skb, msglen);
553 	}
554 done:
555 	if (status & NFNL_BATCH_REPLAY) {
556 		ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
557 		nfnl_err_reset(&err_list);
558 		kfree_skb(skb);
559 		module_put(ss->owner);
560 		goto replay;
561 	} else if (status == NFNL_BATCH_DONE) {
562 		err = ss->commit(net, oskb);
563 		if (err == -EAGAIN) {
564 			status |= NFNL_BATCH_REPLAY;
565 			goto done;
566 		} else if (err) {
567 			ss->abort(net, oskb, NFNL_ABORT_NONE);
568 			netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
569 		}
570 	} else {
571 		enum nfnl_abort_action abort_action;
572 
573 		if (status & NFNL_BATCH_FAILURE)
574 			abort_action = NFNL_ABORT_NONE;
575 		else
576 			abort_action = NFNL_ABORT_VALIDATE;
577 
578 		err = ss->abort(net, oskb, abort_action);
579 		if (err == -EAGAIN) {
580 			nfnl_err_reset(&err_list);
581 			kfree_skb(skb);
582 			module_put(ss->owner);
583 			status |= NFNL_BATCH_FAILURE;
584 			goto replay_abort;
585 		}
586 	}
587 	if (ss->cleanup)
588 		ss->cleanup(net);
589 
590 	nfnl_err_deliver(&err_list, oskb);
591 	kfree_skb(skb);
592 	module_put(ss->owner);
593 }
594 
595 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
596 	[NFNL_BATCH_GENID]	= { .type = NLA_U32 },
597 };
598 
599 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
600 {
601 	int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
602 	struct nlattr *attr = (void *)nlh + min_len;
603 	struct nlattr *cda[NFNL_BATCH_MAX + 1];
604 	int attrlen = nlh->nlmsg_len - min_len;
605 	struct nfgenmsg *nfgenmsg;
606 	int msglen, err;
607 	u32 gen_id = 0;
608 	u16 res_id;
609 
610 	msglen = NLMSG_ALIGN(nlh->nlmsg_len);
611 	if (msglen > skb->len)
612 		msglen = skb->len;
613 
614 	if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
615 		return;
616 
617 	err = nla_parse_deprecated(cda, NFNL_BATCH_MAX, attr, attrlen,
618 				   nfnl_batch_policy, NULL);
619 	if (err < 0) {
620 		netlink_ack(skb, nlh, err, NULL);
621 		return;
622 	}
623 	if (cda[NFNL_BATCH_GENID])
624 		gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
625 
626 	nfgenmsg = nlmsg_data(nlh);
627 	skb_pull(skb, msglen);
628 	/* Work around old nft using host byte order */
629 	if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
630 		res_id = NFNL_SUBSYS_NFTABLES;
631 	else
632 		res_id = ntohs(nfgenmsg->res_id);
633 
634 	nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
635 }
636 
637 static void nfnetlink_rcv(struct sk_buff *skb)
638 {
639 	struct nlmsghdr *nlh = nlmsg_hdr(skb);
640 
641 	if (skb->len < NLMSG_HDRLEN ||
642 	    nlh->nlmsg_len < NLMSG_HDRLEN ||
643 	    skb->len < nlh->nlmsg_len)
644 		return;
645 
646 	if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
647 		netlink_ack(skb, nlh, -EPERM, NULL);
648 		return;
649 	}
650 
651 	if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
652 		nfnetlink_rcv_skb_batch(skb, nlh);
653 	else
654 		netlink_rcv_skb(skb, nfnetlink_rcv_msg);
655 }
656 
657 static int nfnetlink_bind(struct net *net, int group)
658 {
659 	const struct nfnetlink_subsystem *ss;
660 	int type;
661 
662 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
663 		return 0;
664 
665 	type = nfnl_group2type[group];
666 
667 	rcu_read_lock();
668 	ss = nfnetlink_get_subsys(type << 8);
669 	rcu_read_unlock();
670 	if (!ss)
671 		request_module_nowait("nfnetlink-subsys-%d", type);
672 
673 #ifdef CONFIG_NF_CONNTRACK_EVENTS
674 	if (type == NFNL_SUBSYS_CTNETLINK) {
675 		nfnl_lock(NFNL_SUBSYS_CTNETLINK);
676 		WRITE_ONCE(net->ct.ctnetlink_has_listener, true);
677 		nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
678 	}
679 #endif
680 	return 0;
681 }
682 
683 static void nfnetlink_unbind(struct net *net, int group)
684 {
685 #ifdef CONFIG_NF_CONNTRACK_EVENTS
686 	if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
687 		return;
688 
689 	if (nfnl_group2type[group] == NFNL_SUBSYS_CTNETLINK) {
690 		nfnl_lock(NFNL_SUBSYS_CTNETLINK);
691 		if (!nfnetlink_has_listeners(net, group))
692 			WRITE_ONCE(net->ct.ctnetlink_has_listener, false);
693 		nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
694 	}
695 #endif
696 }
697 
698 static int __net_init nfnetlink_net_init(struct net *net)
699 {
700 	struct nfnl_net *nfnlnet = nfnl_pernet(net);
701 	struct netlink_kernel_cfg cfg = {
702 		.groups	= NFNLGRP_MAX,
703 		.input	= nfnetlink_rcv,
704 		.bind	= nfnetlink_bind,
705 		.unbind	= nfnetlink_unbind,
706 	};
707 
708 	nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
709 	if (!nfnlnet->nfnl)
710 		return -ENOMEM;
711 	return 0;
712 }
713 
714 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
715 {
716 	struct nfnl_net *nfnlnet;
717 	struct net *net;
718 
719 	list_for_each_entry(net, net_exit_list, exit_list) {
720 		nfnlnet = nfnl_pernet(net);
721 
722 		netlink_kernel_release(nfnlnet->nfnl);
723 	}
724 }
725 
726 static struct pernet_operations nfnetlink_net_ops = {
727 	.init		= nfnetlink_net_init,
728 	.exit_batch	= nfnetlink_net_exit_batch,
729 	.id		= &nfnetlink_pernet_id,
730 	.size		= sizeof(struct nfnl_net),
731 };
732 
733 static int __init nfnetlink_init(void)
734 {
735 	int i;
736 
737 	for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
738 		BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
739 
740 	for (i=0; i<NFNL_SUBSYS_COUNT; i++)
741 		__mutex_init(&table[i].mutex, nfnl_lockdep_names[i], &nfnl_lockdep_keys[i]);
742 
743 	return register_pernet_subsys(&nfnetlink_net_ops);
744 }
745 
746 static void __exit nfnetlink_exit(void)
747 {
748 	unregister_pernet_subsys(&nfnetlink_net_ops);
749 }
750 module_init(nfnetlink_init);
751 module_exit(nfnetlink_exit);
752