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.h>
33#include <linux/netfilter/nfnetlink.h>
34
35MODULE_LICENSE("GPL");
36MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
37MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
38MODULE_DESCRIPTION("Netfilter messages via netlink socket");
39
40#define nfnl_dereference_protected(id) \
41 rcu_dereference_protected(table[(id)].subsys, \
42 lockdep_nfnl_is_held((id)))
43
44#define NFNL_MAX_ATTR_COUNT 32
45
46static unsigned int nfnetlink_pernet_id __read_mostly;
47
48#ifdef CONFIG_NF_CONNTRACK_EVENTS
49static DEFINE_SPINLOCK(nfnl_grp_active_lock);
50#endif
51
52struct nfnl_net {
53 struct sock *nfnl;
54};
55
56static struct {
57 struct mutex mutex;
58 const struct nfnetlink_subsystem __rcu *subsys;
59} table[NFNL_SUBSYS_COUNT];
60
61static struct lock_class_key nfnl_lockdep_keys[NFNL_SUBSYS_COUNT];
62
63static const char *const nfnl_lockdep_names[NFNL_SUBSYS_COUNT] = {
64 [NFNL_SUBSYS_NONE] = "nfnl_subsys_none",
65 [NFNL_SUBSYS_CTNETLINK] = "nfnl_subsys_ctnetlink",
66 [NFNL_SUBSYS_CTNETLINK_EXP] = "nfnl_subsys_ctnetlink_exp",
67 [NFNL_SUBSYS_QUEUE] = "nfnl_subsys_queue",
68 [NFNL_SUBSYS_ULOG] = "nfnl_subsys_ulog",
69 [NFNL_SUBSYS_OSF] = "nfnl_subsys_osf",
70 [NFNL_SUBSYS_IPSET] = "nfnl_subsys_ipset",
71 [NFNL_SUBSYS_ACCT] = "nfnl_subsys_acct",
72 [NFNL_SUBSYS_CTNETLINK_TIMEOUT] = "nfnl_subsys_cttimeout",
73 [NFNL_SUBSYS_CTHELPER] = "nfnl_subsys_cthelper",
74 [NFNL_SUBSYS_NFTABLES] = "nfnl_subsys_nftables",
75 [NFNL_SUBSYS_NFT_COMPAT] = "nfnl_subsys_nftcompat",
76 [NFNL_SUBSYS_HOOK] = "nfnl_subsys_hook",
77};
78
79static const int nfnl_group2type[NFNLGRP_MAX+1] = {
80 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
81 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK,
82 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK,
83 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP,
84 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP,
85 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
86 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES,
87 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT,
88 [NFNLGRP_NFTRACE] = NFNL_SUBSYS_NFTABLES,
89};
90
91static struct nfnl_net *nfnl_pernet(struct net *net)
92{
93 return net_generic(net, id: nfnetlink_pernet_id);
94}
95
96void nfnl_lock(__u8 subsys_id)
97{
98 mutex_lock(&table[subsys_id].mutex);
99}
100EXPORT_SYMBOL_GPL(nfnl_lock);
101
102void nfnl_unlock(__u8 subsys_id)
103{
104 mutex_unlock(lock: &table[subsys_id].mutex);
105}
106EXPORT_SYMBOL_GPL(nfnl_unlock);
107
108#ifdef CONFIG_PROVE_LOCKING
109bool lockdep_nfnl_is_held(u8 subsys_id)
110{
111 return lockdep_is_held(&table[subsys_id].mutex);
112}
113EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
114#endif
115
116int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
117{
118 u8 cb_id;
119
120 /* Sanity-check attr_count size to avoid stack buffer overflow. */
121 for (cb_id = 0; cb_id < n->cb_count; cb_id++)
122 if (WARN_ON(n->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT))
123 return -EINVAL;
124
125 nfnl_lock(n->subsys_id);
126 if (table[n->subsys_id].subsys) {
127 nfnl_unlock(n->subsys_id);
128 return -EBUSY;
129 }
130 rcu_assign_pointer(table[n->subsys_id].subsys, n);
131 nfnl_unlock(n->subsys_id);
132
133 return 0;
134}
135EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
136
137int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
138{
139 nfnl_lock(n->subsys_id);
140 table[n->subsys_id].subsys = NULL;
141 nfnl_unlock(n->subsys_id);
142 synchronize_rcu();
143 return 0;
144}
145EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
146
147static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
148{
149 u8 subsys_id = NFNL_SUBSYS_ID(type);
150
151 if (subsys_id >= NFNL_SUBSYS_COUNT)
152 return NULL;
153
154 return rcu_dereference(table[subsys_id].subsys);
155}
156
157static inline const struct nfnl_callback *
158nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
159{
160 u8 cb_id = NFNL_MSG_TYPE(type);
161
162 if (cb_id >= ss->cb_count)
163 return NULL;
164
165 return &ss->cb[cb_id];
166}
167
168int nfnetlink_has_listeners(struct net *net, unsigned int group)
169{
170 struct nfnl_net *nfnlnet = nfnl_pernet(net);
171
172 return netlink_has_listeners(sk: nfnlnet->nfnl, group);
173}
174EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
175
176int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
177 unsigned int group, int echo, gfp_t flags)
178{
179 struct nfnl_net *nfnlnet = nfnl_pernet(net);
180
181 return nlmsg_notify(sk: nfnlnet->nfnl, skb, portid, group, report: echo, flags);
182}
183EXPORT_SYMBOL_GPL(nfnetlink_send);
184
185int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
186{
187 struct nfnl_net *nfnlnet = nfnl_pernet(net);
188
189 return netlink_set_err(ssk: nfnlnet->nfnl, portid, group, code: error);
190}
191EXPORT_SYMBOL_GPL(nfnetlink_set_err);
192
193int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid)
194{
195 struct nfnl_net *nfnlnet = nfnl_pernet(net);
196 int err;
197
198 err = nlmsg_unicast(sk: nfnlnet->nfnl, skb, portid);
199 if (err == -EAGAIN)
200 err = -ENOBUFS;
201
202 return err;
203}
204EXPORT_SYMBOL_GPL(nfnetlink_unicast);
205
206void nfnetlink_broadcast(struct net *net, struct sk_buff *skb, __u32 portid,
207 __u32 group, gfp_t allocation)
208{
209 struct nfnl_net *nfnlnet = nfnl_pernet(net);
210
211 netlink_broadcast(ssk: nfnlnet->nfnl, skb, portid, group, allocation);
212}
213EXPORT_SYMBOL_GPL(nfnetlink_broadcast);
214
215/* Process one complete nfnetlink message. */
216static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
217 struct netlink_ext_ack *extack)
218{
219 struct net *net = sock_net(sk: skb->sk);
220 const struct nfnl_callback *nc;
221 const struct nfnetlink_subsystem *ss;
222 int type, err;
223
224 /* All the messages must at least contain nfgenmsg */
225 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
226 return 0;
227
228 type = nlh->nlmsg_type;
229replay:
230 rcu_read_lock();
231
232 ss = nfnetlink_get_subsys(type);
233 if (!ss) {
234#ifdef CONFIG_MODULES
235 rcu_read_unlock();
236 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
237 rcu_read_lock();
238 ss = nfnetlink_get_subsys(type);
239 if (!ss)
240#endif
241 {
242 rcu_read_unlock();
243 return -EINVAL;
244 }
245 }
246
247 nc = nfnetlink_find_client(type, ss);
248 if (!nc) {
249 rcu_read_unlock();
250 return -EINVAL;
251 }
252
253 {
254 int min_len = nlmsg_total_size(payload: sizeof(struct nfgenmsg));
255 struct nfnl_net *nfnlnet = nfnl_pernet(net);
256 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
257 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
258 struct nlattr *attr = (void *)nlh + min_len;
259 int attrlen = nlh->nlmsg_len - min_len;
260 __u8 subsys_id = NFNL_SUBSYS_ID(type);
261 struct nfnl_info info = {
262 .net = net,
263 .sk = nfnlnet->nfnl,
264 .nlh = nlh,
265 .nfmsg = nlmsg_data(nlh),
266 .extack = extack,
267 };
268
269 /* Sanity-check NFNL_MAX_ATTR_COUNT */
270 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
271 rcu_read_unlock();
272 return -ENOMEM;
273 }
274
275 err = nla_parse_deprecated(tb: cda, maxtype: ss->cb[cb_id].attr_count,
276 head: attr, len: attrlen,
277 policy: ss->cb[cb_id].policy, extack);
278 if (err < 0) {
279 rcu_read_unlock();
280 return err;
281 }
282
283 if (!nc->call) {
284 rcu_read_unlock();
285 return -EINVAL;
286 }
287
288 switch (nc->type) {
289 case NFNL_CB_RCU:
290 err = nc->call(skb, &info, (const struct nlattr **)cda);
291 rcu_read_unlock();
292 break;
293 case NFNL_CB_MUTEX:
294 rcu_read_unlock();
295 nfnl_lock(subsys_id);
296 if (nfnl_dereference_protected(subsys_id) != ss ||
297 nfnetlink_find_client(type, ss) != nc) {
298 nfnl_unlock(subsys_id);
299 err = -EAGAIN;
300 break;
301 }
302 err = nc->call(skb, &info, (const struct nlattr **)cda);
303 nfnl_unlock(subsys_id);
304 break;
305 default:
306 rcu_read_unlock();
307 err = -EINVAL;
308 break;
309 }
310 if (err == -EAGAIN)
311 goto replay;
312 return err;
313 }
314}
315
316struct nfnl_err {
317 struct list_head head;
318 struct nlmsghdr *nlh;
319 int err;
320 struct netlink_ext_ack extack;
321};
322
323static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
324 const struct netlink_ext_ack *extack)
325{
326 struct nfnl_err *nfnl_err;
327
328 nfnl_err = kmalloc(size: sizeof(struct nfnl_err), GFP_KERNEL);
329 if (nfnl_err == NULL)
330 return -ENOMEM;
331
332 nfnl_err->nlh = nlh;
333 nfnl_err->err = err;
334 nfnl_err->extack = *extack;
335 list_add_tail(new: &nfnl_err->head, head: list);
336
337 return 0;
338}
339
340static void nfnl_err_del(struct nfnl_err *nfnl_err)
341{
342 list_del(entry: &nfnl_err->head);
343 kfree(objp: nfnl_err);
344}
345
346static void nfnl_err_reset(struct list_head *err_list)
347{
348 struct nfnl_err *nfnl_err, *next;
349
350 list_for_each_entry_safe(nfnl_err, next, err_list, head)
351 nfnl_err_del(nfnl_err);
352}
353
354static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
355{
356 struct nfnl_err *nfnl_err, *next;
357
358 list_for_each_entry_safe(nfnl_err, next, err_list, head) {
359 netlink_ack(in_skb: skb, nlh: nfnl_err->nlh, err: nfnl_err->err,
360 extack: &nfnl_err->extack);
361 nfnl_err_del(nfnl_err);
362 }
363}
364
365enum {
366 NFNL_BATCH_FAILURE = (1 << 0),
367 NFNL_BATCH_DONE = (1 << 1),
368 NFNL_BATCH_REPLAY = (1 << 2),
369};
370
371static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
372 u16 subsys_id, u32 genid)
373{
374 struct sk_buff *oskb = skb;
375 struct net *net = sock_net(sk: skb->sk);
376 const struct nfnetlink_subsystem *ss;
377 const struct nfnl_callback *nc;
378 struct netlink_ext_ack extack;
379 LIST_HEAD(err_list);
380 u32 status;
381 int err;
382
383 if (subsys_id >= NFNL_SUBSYS_COUNT)
384 return netlink_ack(in_skb: skb, nlh, err: -EINVAL, NULL);
385replay:
386 status = 0;
387replay_abort:
388 skb = netlink_skb_clone(skb: oskb, GFP_KERNEL);
389 if (!skb)
390 return netlink_ack(in_skb: oskb, nlh, err: -ENOMEM, NULL);
391
392 nfnl_lock(subsys_id);
393 ss = nfnl_dereference_protected(subsys_id);
394 if (!ss) {
395#ifdef CONFIG_MODULES
396 nfnl_unlock(subsys_id);
397 request_module("nfnetlink-subsys-%d", subsys_id);
398 nfnl_lock(subsys_id);
399 ss = nfnl_dereference_protected(subsys_id);
400 if (!ss)
401#endif
402 {
403 nfnl_unlock(subsys_id);
404 netlink_ack(in_skb: oskb, nlh, err: -EOPNOTSUPP, NULL);
405 return kfree_skb(skb);
406 }
407 }
408
409 if (!ss->valid_genid || !ss->commit || !ss->abort) {
410 nfnl_unlock(subsys_id);
411 netlink_ack(in_skb: oskb, nlh, err: -EOPNOTSUPP, NULL);
412 return kfree_skb(skb);
413 }
414
415 if (!try_module_get(module: ss->owner)) {
416 nfnl_unlock(subsys_id);
417 netlink_ack(in_skb: oskb, nlh, err: -EOPNOTSUPP, NULL);
418 return kfree_skb(skb);
419 }
420
421 if (!ss->valid_genid(net, genid)) {
422 module_put(module: ss->owner);
423 nfnl_unlock(subsys_id);
424 netlink_ack(in_skb: oskb, nlh, err: -ERESTART, NULL);
425 return kfree_skb(skb);
426 }
427
428 nfnl_unlock(subsys_id);
429
430 while (skb->len >= nlmsg_total_size(payload: 0)) {
431 int msglen, type;
432
433 if (fatal_signal_pending(current)) {
434 nfnl_err_reset(err_list: &err_list);
435 err = -EINTR;
436 status = NFNL_BATCH_FAILURE;
437 goto done;
438 }
439
440 memset(&extack, 0, sizeof(extack));
441 nlh = nlmsg_hdr(skb);
442 err = 0;
443
444 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
445 skb->len < nlh->nlmsg_len ||
446 nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
447 nfnl_err_reset(err_list: &err_list);
448 status |= NFNL_BATCH_FAILURE;
449 goto done;
450 }
451
452 /* Only requests are handled by the kernel */
453 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
454 err = -EINVAL;
455 goto ack;
456 }
457
458 type = nlh->nlmsg_type;
459 if (type == NFNL_MSG_BATCH_BEGIN) {
460 /* Malformed: Batch begin twice */
461 nfnl_err_reset(err_list: &err_list);
462 status |= NFNL_BATCH_FAILURE;
463 goto done;
464 } else if (type == NFNL_MSG_BATCH_END) {
465 status |= NFNL_BATCH_DONE;
466 goto done;
467 } else if (type < NLMSG_MIN_TYPE) {
468 err = -EINVAL;
469 goto ack;
470 }
471
472 /* We only accept a batch with messages for the same
473 * subsystem.
474 */
475 if (NFNL_SUBSYS_ID(type) != subsys_id) {
476 err = -EINVAL;
477 goto ack;
478 }
479
480 nc = nfnetlink_find_client(type, ss);
481 if (!nc) {
482 err = -EINVAL;
483 goto ack;
484 }
485
486 if (nc->type != NFNL_CB_BATCH) {
487 err = -EINVAL;
488 goto ack;
489 }
490
491 {
492 int min_len = nlmsg_total_size(payload: sizeof(struct nfgenmsg));
493 struct nfnl_net *nfnlnet = nfnl_pernet(net);
494 struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
495 struct nlattr *attr = (void *)nlh + min_len;
496 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
497 int attrlen = nlh->nlmsg_len - min_len;
498 struct nfnl_info info = {
499 .net = net,
500 .sk = nfnlnet->nfnl,
501 .nlh = nlh,
502 .nfmsg = nlmsg_data(nlh),
503 .extack = &extack,
504 };
505
506 /* Sanity-check NFTA_MAX_ATTR */
507 if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
508 err = -ENOMEM;
509 goto ack;
510 }
511
512 err = nla_parse_deprecated(tb: cda,
513 maxtype: ss->cb[cb_id].attr_count,
514 head: attr, len: attrlen,
515 policy: ss->cb[cb_id].policy, NULL);
516 if (err < 0)
517 goto ack;
518
519 err = nc->call(skb, &info, (const struct nlattr **)cda);
520
521 /* The lock was released to autoload some module, we
522 * have to abort and start from scratch using the
523 * original skb.
524 */
525 if (err == -EAGAIN) {
526 status |= NFNL_BATCH_REPLAY;
527 goto done;
528 }
529 }
530ack:
531 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
532 /* Errors are delivered once the full batch has been
533 * processed, this avoids that the same error is
534 * reported several times when replaying the batch.
535 */
536 if (err == -ENOMEM ||
537 nfnl_err_add(list: &err_list, nlh, err, extack: &extack) < 0) {
538 /* We failed to enqueue an error, reset the
539 * list of errors and send OOM to userspace
540 * pointing to the batch header.
541 */
542 nfnl_err_reset(err_list: &err_list);
543 netlink_ack(in_skb: oskb, nlh: nlmsg_hdr(skb: oskb), err: -ENOMEM,
544 NULL);
545 status |= NFNL_BATCH_FAILURE;
546 goto done;
547 }
548 /* We don't stop processing the batch on errors, thus,
549 * userspace gets all the errors that the batch
550 * triggers.
551 */
552 if (err)
553 status |= NFNL_BATCH_FAILURE;
554 }
555
556 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
557 if (msglen > skb->len)
558 msglen = skb->len;
559 skb_pull(skb, len: msglen);
560 }
561done:
562 if (status & NFNL_BATCH_REPLAY) {
563 ss->abort(net, oskb, NFNL_ABORT_AUTOLOAD);
564 nfnl_err_reset(err_list: &err_list);
565 kfree_skb(skb);
566 module_put(module: ss->owner);
567 goto replay;
568 } else if (status == NFNL_BATCH_DONE) {
569 err = ss->commit(net, oskb);
570 if (err == -EAGAIN) {
571 status |= NFNL_BATCH_REPLAY;
572 goto done;
573 } else if (err) {
574 ss->abort(net, oskb, NFNL_ABORT_NONE);
575 netlink_ack(in_skb: oskb, nlh: nlmsg_hdr(skb: oskb), err, NULL);
576 }
577 } else {
578 enum nfnl_abort_action abort_action;
579
580 if (status & NFNL_BATCH_FAILURE)
581 abort_action = NFNL_ABORT_NONE;
582 else
583 abort_action = NFNL_ABORT_VALIDATE;
584
585 err = ss->abort(net, oskb, abort_action);
586 if (err == -EAGAIN) {
587 nfnl_err_reset(err_list: &err_list);
588 kfree_skb(skb);
589 module_put(module: ss->owner);
590 status |= NFNL_BATCH_FAILURE;
591 goto replay_abort;
592 }
593 }
594
595 nfnl_err_deliver(err_list: &err_list, skb: oskb);
596 kfree_skb(skb);
597 module_put(module: ss->owner);
598}
599
600static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
601 [NFNL_BATCH_GENID] = { .type = NLA_U32 },
602};
603
604static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
605{
606 int min_len = nlmsg_total_size(payload: sizeof(struct nfgenmsg));
607 struct nlattr *attr = (void *)nlh + min_len;
608 struct nlattr *cda[NFNL_BATCH_MAX + 1];
609 int attrlen = nlh->nlmsg_len - min_len;
610 struct nfgenmsg *nfgenmsg;
611 int msglen, err;
612 u32 gen_id = 0;
613 u16 res_id;
614
615 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
616 if (msglen > skb->len)
617 msglen = skb->len;
618
619 if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
620 return;
621
622 err = nla_parse_deprecated(tb: cda, NFNL_BATCH_MAX, head: attr, len: attrlen,
623 policy: nfnl_batch_policy, NULL);
624 if (err < 0) {
625 netlink_ack(in_skb: skb, nlh, err, NULL);
626 return;
627 }
628 if (cda[NFNL_BATCH_GENID])
629 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
630
631 nfgenmsg = nlmsg_data(nlh);
632 skb_pull(skb, len: msglen);
633 /* Work around old nft using host byte order */
634 if (nfgenmsg->res_id == (__force __be16)NFNL_SUBSYS_NFTABLES)
635 res_id = NFNL_SUBSYS_NFTABLES;
636 else
637 res_id = ntohs(nfgenmsg->res_id);
638
639 nfnetlink_rcv_batch(skb, nlh, subsys_id: res_id, genid: gen_id);
640}
641
642static void nfnetlink_rcv(struct sk_buff *skb)
643{
644 struct nlmsghdr *nlh = nlmsg_hdr(skb);
645
646 if (skb->len < NLMSG_HDRLEN ||
647 nlh->nlmsg_len < NLMSG_HDRLEN ||
648 skb->len < nlh->nlmsg_len)
649 return;
650
651 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
652 netlink_ack(in_skb: skb, nlh, err: -EPERM, NULL);
653 return;
654 }
655
656 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
657 nfnetlink_rcv_skb_batch(skb, nlh);
658 else
659 netlink_rcv_skb(skb, cb: nfnetlink_rcv_msg);
660}
661
662static void nfnetlink_bind_event(struct net *net, unsigned int group)
663{
664#ifdef CONFIG_NF_CONNTRACK_EVENTS
665 int type, group_bit;
666 u8 v;
667
668 /* All NFNLGRP_CONNTRACK_* group bits fit into u8.
669 * The other groups are not relevant and can be ignored.
670 */
671 if (group >= 8)
672 return;
673
674 type = nfnl_group2type[group];
675
676 switch (type) {
677 case NFNL_SUBSYS_CTNETLINK:
678 break;
679 case NFNL_SUBSYS_CTNETLINK_EXP:
680 break;
681 default:
682 return;
683 }
684
685 group_bit = (1 << group);
686
687 spin_lock(lock: &nfnl_grp_active_lock);
688 v = READ_ONCE(nf_ctnetlink_has_listener);
689 if ((v & group_bit) == 0) {
690 v |= group_bit;
691
692 /* read concurrently without nfnl_grp_active_lock held. */
693 WRITE_ONCE(nf_ctnetlink_has_listener, v);
694 }
695
696 spin_unlock(lock: &nfnl_grp_active_lock);
697#endif
698}
699
700static int nfnetlink_bind(struct net *net, int group)
701{
702 const struct nfnetlink_subsystem *ss;
703 int type;
704
705 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
706 return 0;
707
708 type = nfnl_group2type[group];
709
710 rcu_read_lock();
711 ss = nfnetlink_get_subsys(type: type << 8);
712 rcu_read_unlock();
713 if (!ss)
714 request_module_nowait("nfnetlink-subsys-%d", type);
715
716 nfnetlink_bind_event(net, group);
717 return 0;
718}
719
720static void nfnetlink_unbind(struct net *net, int group)
721{
722#ifdef CONFIG_NF_CONNTRACK_EVENTS
723 int type, group_bit;
724
725 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
726 return;
727
728 type = nfnl_group2type[group];
729
730 switch (type) {
731 case NFNL_SUBSYS_CTNETLINK:
732 break;
733 case NFNL_SUBSYS_CTNETLINK_EXP:
734 break;
735 default:
736 return;
737 }
738
739 /* ctnetlink_has_listener is u8 */
740 if (group >= 8)
741 return;
742
743 group_bit = (1 << group);
744
745 spin_lock(lock: &nfnl_grp_active_lock);
746 if (!nfnetlink_has_listeners(net, group)) {
747 u8 v = READ_ONCE(nf_ctnetlink_has_listener);
748
749 v &= ~group_bit;
750
751 /* read concurrently without nfnl_grp_active_lock held. */
752 WRITE_ONCE(nf_ctnetlink_has_listener, v);
753 }
754 spin_unlock(lock: &nfnl_grp_active_lock);
755#endif
756}
757
758static int __net_init nfnetlink_net_init(struct net *net)
759{
760 struct nfnl_net *nfnlnet = nfnl_pernet(net);
761 struct netlink_kernel_cfg cfg = {
762 .groups = NFNLGRP_MAX,
763 .input = nfnetlink_rcv,
764 .bind = nfnetlink_bind,
765 .unbind = nfnetlink_unbind,
766 };
767
768 nfnlnet->nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, cfg: &cfg);
769 if (!nfnlnet->nfnl)
770 return -ENOMEM;
771 return 0;
772}
773
774static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
775{
776 struct nfnl_net *nfnlnet;
777 struct net *net;
778
779 list_for_each_entry(net, net_exit_list, exit_list) {
780 nfnlnet = nfnl_pernet(net);
781
782 netlink_kernel_release(sk: nfnlnet->nfnl);
783 }
784}
785
786static struct pernet_operations nfnetlink_net_ops = {
787 .init = nfnetlink_net_init,
788 .exit_batch = nfnetlink_net_exit_batch,
789 .id = &nfnetlink_pernet_id,
790 .size = sizeof(struct nfnl_net),
791};
792
793static int __init nfnetlink_init(void)
794{
795 int i;
796
797 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
798 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
799
800 for (i=0; i<NFNL_SUBSYS_COUNT; i++)
801 __mutex_init(lock: &table[i].mutex, name: nfnl_lockdep_names[i], key: &nfnl_lockdep_keys[i]);
802
803 return register_pernet_subsys(&nfnetlink_net_ops);
804}
805
806static void __exit nfnetlink_exit(void)
807{
808 unregister_pernet_subsys(&nfnetlink_net_ops);
809}
810module_init(nfnetlink_init);
811module_exit(nfnetlink_exit);
812

source code of linux/net/netfilter/nfnetlink.c