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Linux/net/netfilter/nfnetlink.c

Version: ~ [ linux-5.6-rc1 ] ~ [ linux-5.5.2 ] ~ [ linux-5.4.17 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.102 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.170 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.213 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.213 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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(cda, ss->cb[cb_id].attr_count, attr, attrlen,
210                                 ss->cb[cb_id].policy, extack);
211                 if (err < 0) {
212                         rcu_read_unlock();
213                         return err;
214                 }
215 
216                 if (nc->call_rcu) {
217                         err = nc->call_rcu(net, net->nfnl, skb, nlh,
218                                            (const struct nlattr **)cda,
219                                            extack);
220                         rcu_read_unlock();
221                 } else {
222                         rcu_read_unlock();
223                         nfnl_lock(subsys_id);
224                         if (nfnl_dereference_protected(subsys_id) != ss ||
225                             nfnetlink_find_client(type, ss) != nc)
226                                 err = -EAGAIN;
227                         else if (nc->call)
228                                 err = nc->call(net, net->nfnl, skb, nlh,
229                                                (const struct nlattr **)cda,
230                                                extack);
231                         else
232                                 err = -EINVAL;
233                         nfnl_unlock(subsys_id);
234                 }
235                 if (err == -EAGAIN)
236                         goto replay;
237                 return err;
238         }
239 }
240 
241 struct nfnl_err {
242         struct list_head        head;
243         struct nlmsghdr         *nlh;
244         int                     err;
245         struct netlink_ext_ack  extack;
246 };
247 
248 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
249                         const struct netlink_ext_ack *extack)
250 {
251         struct nfnl_err *nfnl_err;
252 
253         nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
254         if (nfnl_err == NULL)
255                 return -ENOMEM;
256 
257         nfnl_err->nlh = nlh;
258         nfnl_err->err = err;
259         nfnl_err->extack = *extack;
260         list_add_tail(&nfnl_err->head, list);
261 
262         return 0;
263 }
264 
265 static void nfnl_err_del(struct nfnl_err *nfnl_err)
266 {
267         list_del(&nfnl_err->head);
268         kfree(nfnl_err);
269 }
270 
271 static void nfnl_err_reset(struct list_head *err_list)
272 {
273         struct nfnl_err *nfnl_err, *next;
274 
275         list_for_each_entry_safe(nfnl_err, next, err_list, head)
276                 nfnl_err_del(nfnl_err);
277 }
278 
279 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
280 {
281         struct nfnl_err *nfnl_err, *next;
282 
283         list_for_each_entry_safe(nfnl_err, next, err_list, head) {
284                 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
285                             &nfnl_err->extack);
286                 nfnl_err_del(nfnl_err);
287         }
288 }
289 
290 enum {
291         NFNL_BATCH_FAILURE      = (1 << 0),
292         NFNL_BATCH_DONE         = (1 << 1),
293         NFNL_BATCH_REPLAY       = (1 << 2),
294 };
295 
296 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
297                                 u16 subsys_id, u32 genid)
298 {
299         struct sk_buff *oskb = skb;
300         struct net *net = sock_net(skb->sk);
301         const struct nfnetlink_subsystem *ss;
302         const struct nfnl_callback *nc;
303         struct netlink_ext_ack extack;
304         LIST_HEAD(err_list);
305         u32 status;
306         int err;
307 
308         if (subsys_id >= NFNL_SUBSYS_COUNT)
309                 return netlink_ack(skb, nlh, -EINVAL, NULL);
310 replay:
311         status = 0;
312 
313         skb = netlink_skb_clone(oskb, GFP_KERNEL);
314         if (!skb)
315                 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
316 
317         nfnl_lock(subsys_id);
318         ss = nfnl_dereference_protected(subsys_id);
319         if (!ss) {
320 #ifdef CONFIG_MODULES
321                 nfnl_unlock(subsys_id);
322                 request_module("nfnetlink-subsys-%d", subsys_id);
323                 nfnl_lock(subsys_id);
324                 ss = nfnl_dereference_protected(subsys_id);
325                 if (!ss)
326 #endif
327                 {
328                         nfnl_unlock(subsys_id);
329                         netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
330                         return kfree_skb(skb);
331                 }
332         }
333 
334         if (!ss->valid_genid || !ss->commit || !ss->abort) {
335                 nfnl_unlock(subsys_id);
336                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
337                 return kfree_skb(skb);
338         }
339 
340         if (!try_module_get(ss->owner)) {
341                 nfnl_unlock(subsys_id);
342                 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
343                 return kfree_skb(skb);
344         }
345 
346         if (!ss->valid_genid(net, genid)) {
347                 module_put(ss->owner);
348                 nfnl_unlock(subsys_id);
349                 netlink_ack(oskb, nlh, -ERESTART, NULL);
350                 return kfree_skb(skb);
351         }
352 
353         nfnl_unlock(subsys_id);
354 
355         while (skb->len >= nlmsg_total_size(0)) {
356                 int msglen, type;
357 
358                 if (fatal_signal_pending(current)) {
359                         nfnl_err_reset(&err_list);
360                         err = -EINTR;
361                         status = NFNL_BATCH_FAILURE;
362                         goto done;
363                 }
364 
365                 memset(&extack, 0, sizeof(extack));
366                 nlh = nlmsg_hdr(skb);
367                 err = 0;
368 
369                 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
370                     skb->len < nlh->nlmsg_len ||
371                     nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
372                         nfnl_err_reset(&err_list);
373                         status |= NFNL_BATCH_FAILURE;
374                         goto done;
375                 }
376 
377                 /* Only requests are handled by the kernel */
378                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
379                         err = -EINVAL;
380                         goto ack;
381                 }
382 
383                 type = nlh->nlmsg_type;
384                 if (type == NFNL_MSG_BATCH_BEGIN) {
385                         /* Malformed: Batch begin twice */
386                         nfnl_err_reset(&err_list);
387                         status |= NFNL_BATCH_FAILURE;
388                         goto done;
389                 } else if (type == NFNL_MSG_BATCH_END) {
390                         status |= NFNL_BATCH_DONE;
391                         goto done;
392                 } else if (type < NLMSG_MIN_TYPE) {
393                         err = -EINVAL;
394                         goto ack;
395                 }
396 
397                 /* We only accept a batch with messages for the same
398                  * subsystem.
399                  */
400                 if (NFNL_SUBSYS_ID(type) != subsys_id) {
401                         err = -EINVAL;
402                         goto ack;
403                 }
404 
405                 nc = nfnetlink_find_client(type, ss);
406                 if (!nc) {
407                         err = -EINVAL;
408                         goto ack;
409                 }
410 
411                 {
412                         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
413                         u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
414                         struct nlattr *cda[NFNL_MAX_ATTR_COUNT + 1];
415                         struct nlattr *attr = (void *)nlh + min_len;
416                         int attrlen = nlh->nlmsg_len - min_len;
417 
418                         /* Sanity-check NFTA_MAX_ATTR */
419                         if (ss->cb[cb_id].attr_count > NFNL_MAX_ATTR_COUNT) {
420                                 err = -ENOMEM;
421                                 goto ack;
422                         }
423 
424                         err = nla_parse(cda, ss->cb[cb_id].attr_count, attr,
425                                         attrlen, ss->cb[cb_id].policy, NULL);
426                         if (err < 0)
427                                 goto ack;
428 
429                         if (nc->call_batch) {
430                                 err = nc->call_batch(net, net->nfnl, skb, nlh,
431                                                      (const struct nlattr **)cda,
432                                                      &extack);
433                         }
434 
435                         /* The lock was released to autoload some module, we
436                          * have to abort and start from scratch using the
437                          * original skb.
438                          */
439                         if (err == -EAGAIN) {
440                                 status |= NFNL_BATCH_REPLAY;
441                                 goto done;
442                         }
443                 }
444 ack:
445                 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
446                         /* Errors are delivered once the full batch has been
447                          * processed, this avoids that the same error is
448                          * reported several times when replaying the batch.
449                          */
450                         if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
451                                 /* We failed to enqueue an error, reset the
452                                  * list of errors and send OOM to userspace
453                                  * pointing to the batch header.
454                                  */
455                                 nfnl_err_reset(&err_list);
456                                 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
457                                             NULL);
458                                 status |= NFNL_BATCH_FAILURE;
459                                 goto done;
460                         }
461                         /* We don't stop processing the batch on errors, thus,
462                          * userspace gets all the errors that the batch
463                          * triggers.
464                          */
465                         if (err)
466                                 status |= NFNL_BATCH_FAILURE;
467                 }
468 
469                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
470                 if (msglen > skb->len)
471                         msglen = skb->len;
472                 skb_pull(skb, msglen);
473         }
474 done:
475         if (status & NFNL_BATCH_REPLAY) {
476                 ss->abort(net, oskb);
477                 nfnl_err_reset(&err_list);
478                 kfree_skb(skb);
479                 module_put(ss->owner);
480                 goto replay;
481         } else if (status == NFNL_BATCH_DONE) {
482                 err = ss->commit(net, oskb);
483                 if (err == -EAGAIN) {
484                         status |= NFNL_BATCH_REPLAY;
485                         goto done;
486                 } else if (err) {
487                         ss->abort(net, oskb);
488                         netlink_ack(oskb, nlmsg_hdr(oskb), err, NULL);
489                 }
490         } else {
491                 ss->abort(net, oskb);
492         }
493         if (ss->cleanup)
494                 ss->cleanup(net);
495 
496         nfnl_err_deliver(&err_list, oskb);
497         kfree_skb(skb);
498         module_put(ss->owner);
499 }
500 
501 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
502         [NFNL_BATCH_GENID]      = { .type = NLA_U32 },
503 };
504 
505 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
506 {
507         int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
508         struct nlattr *attr = (void *)nlh + min_len;
509         struct nlattr *cda[NFNL_BATCH_MAX + 1];
510         int attrlen = nlh->nlmsg_len - min_len;
511         struct nfgenmsg *nfgenmsg;
512         int msglen, err;
513         u32 gen_id = 0;
514         u16 res_id;
515 
516         msglen = NLMSG_ALIGN(nlh->nlmsg_len);
517         if (msglen > skb->len)
518                 msglen = skb->len;
519 
520         if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
521                 return;
522 
523         err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy,
524                         NULL);
525         if (err < 0) {
526                 netlink_ack(skb, nlh, err, NULL);
527                 return;
528         }
529         if (cda[NFNL_BATCH_GENID])
530                 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
531 
532         nfgenmsg = nlmsg_data(nlh);
533         skb_pull(skb, msglen);
534         /* Work around old nft using host byte order */
535         if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
536                 res_id = NFNL_SUBSYS_NFTABLES;
537         else
538                 res_id = ntohs(nfgenmsg->res_id);
539 
540         nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
541 }
542 
543 static void nfnetlink_rcv(struct sk_buff *skb)
544 {
545         struct nlmsghdr *nlh = nlmsg_hdr(skb);
546 
547         if (skb->len < NLMSG_HDRLEN ||
548             nlh->nlmsg_len < NLMSG_HDRLEN ||
549             skb->len < nlh->nlmsg_len)
550                 return;
551 
552         if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
553                 netlink_ack(skb, nlh, -EPERM, NULL);
554                 return;
555         }
556 
557         if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
558                 nfnetlink_rcv_skb_batch(skb, nlh);
559         else
560                 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
561 }
562 
563 #ifdef CONFIG_MODULES
564 static int nfnetlink_bind(struct net *net, int group)
565 {
566         const struct nfnetlink_subsystem *ss;
567         int type;
568 
569         if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
570                 return 0;
571 
572         type = nfnl_group2type[group];
573 
574         rcu_read_lock();
575         ss = nfnetlink_get_subsys(type << 8);
576         rcu_read_unlock();
577         if (!ss)
578                 request_module("nfnetlink-subsys-%d", type);
579         return 0;
580 }
581 #endif
582 
583 static int __net_init nfnetlink_net_init(struct net *net)
584 {
585         struct sock *nfnl;
586         struct netlink_kernel_cfg cfg = {
587                 .groups = NFNLGRP_MAX,
588                 .input  = nfnetlink_rcv,
589 #ifdef CONFIG_MODULES
590                 .bind   = nfnetlink_bind,
591 #endif
592         };
593 
594         nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
595         if (!nfnl)
596                 return -ENOMEM;
597         net->nfnl_stash = nfnl;
598         rcu_assign_pointer(net->nfnl, nfnl);
599         return 0;
600 }
601 
602 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
603 {
604         struct net *net;
605 
606         list_for_each_entry(net, net_exit_list, exit_list)
607                 RCU_INIT_POINTER(net->nfnl, NULL);
608         synchronize_net();
609         list_for_each_entry(net, net_exit_list, exit_list)
610                 netlink_kernel_release(net->nfnl_stash);
611 }
612 
613 static struct pernet_operations nfnetlink_net_ops = {
614         .init           = nfnetlink_net_init,
615         .exit_batch     = nfnetlink_net_exit_batch,
616 };
617 
618 static int __init nfnetlink_init(void)
619 {
620         int i;
621 
622         for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
623                 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
624 
625         for (i=0; i<NFNL_SUBSYS_COUNT; i++)
626                 mutex_init(&table[i].mutex);
627 
628         return register_pernet_subsys(&nfnetlink_net_ops);
629 }
630 
631 static void __exit nfnetlink_exit(void)
632 {
633         unregister_pernet_subsys(&nfnetlink_net_ops);
634 }
635 module_init(nfnetlink_init);
636 module_exit(nfnetlink_exit);
637 

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