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Linux/net/netlink/af_netlink.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /*
  3  * NETLINK      Kernel-user communication protocol.
  4  *
  5  *              Authors:        Alan Cox <alan@lxorguk.ukuu.org.uk>
  6  *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  7  *                              Patrick McHardy <kaber@trash.net>
  8  *
  9  * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
 10  *                               added netlink_proto_exit
 11  * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
 12  *                               use nlk_sk, as sk->protinfo is on a diet 8)
 13  * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
 14  *                               - inc module use count of module that owns
 15  *                                 the kernel socket in case userspace opens
 16  *                                 socket of same protocol
 17  *                               - remove all module support, since netlink is
 18  *                                 mandatory if CONFIG_NET=y these days
 19  */
 20 
 21 #include <linux/module.h>
 22 
 23 #include <linux/capability.h>
 24 #include <linux/kernel.h>
 25 #include <linux/init.h>
 26 #include <linux/signal.h>
 27 #include <linux/sched.h>
 28 #include <linux/errno.h>
 29 #include <linux/string.h>
 30 #include <linux/stat.h>
 31 #include <linux/socket.h>
 32 #include <linux/un.h>
 33 #include <linux/fcntl.h>
 34 #include <linux/termios.h>
 35 #include <linux/sockios.h>
 36 #include <linux/net.h>
 37 #include <linux/fs.h>
 38 #include <linux/slab.h>
 39 #include <linux/uaccess.h>
 40 #include <linux/skbuff.h>
 41 #include <linux/netdevice.h>
 42 #include <linux/rtnetlink.h>
 43 #include <linux/proc_fs.h>
 44 #include <linux/seq_file.h>
 45 #include <linux/notifier.h>
 46 #include <linux/security.h>
 47 #include <linux/jhash.h>
 48 #include <linux/jiffies.h>
 49 #include <linux/random.h>
 50 #include <linux/bitops.h>
 51 #include <linux/mm.h>
 52 #include <linux/types.h>
 53 #include <linux/audit.h>
 54 #include <linux/mutex.h>
 55 #include <linux/vmalloc.h>
 56 #include <linux/if_arp.h>
 57 #include <linux/rhashtable.h>
 58 #include <asm/cacheflush.h>
 59 #include <linux/hash.h>
 60 #include <linux/genetlink.h>
 61 #include <linux/net_namespace.h>
 62 #include <linux/nospec.h>
 63 
 64 #include <net/net_namespace.h>
 65 #include <net/netns/generic.h>
 66 #include <net/sock.h>
 67 #include <net/scm.h>
 68 #include <net/netlink.h>
 69 
 70 #include "af_netlink.h"
 71 
 72 struct listeners {
 73         struct rcu_head         rcu;
 74         unsigned long           masks[0];
 75 };
 76 
 77 /* state bits */
 78 #define NETLINK_S_CONGESTED             0x0
 79 
 80 static inline int netlink_is_kernel(struct sock *sk)
 81 {
 82         return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
 83 }
 84 
 85 struct netlink_table *nl_table __read_mostly;
 86 EXPORT_SYMBOL_GPL(nl_table);
 87 
 88 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 89 
 90 static struct lock_class_key nlk_cb_mutex_keys[MAX_LINKS];
 91 
 92 static const char *const nlk_cb_mutex_key_strings[MAX_LINKS + 1] = {
 93         "nlk_cb_mutex-ROUTE",
 94         "nlk_cb_mutex-1",
 95         "nlk_cb_mutex-USERSOCK",
 96         "nlk_cb_mutex-FIREWALL",
 97         "nlk_cb_mutex-SOCK_DIAG",
 98         "nlk_cb_mutex-NFLOG",
 99         "nlk_cb_mutex-XFRM",
100         "nlk_cb_mutex-SELINUX",
101         "nlk_cb_mutex-ISCSI",
102         "nlk_cb_mutex-AUDIT",
103         "nlk_cb_mutex-FIB_LOOKUP",
104         "nlk_cb_mutex-CONNECTOR",
105         "nlk_cb_mutex-NETFILTER",
106         "nlk_cb_mutex-IP6_FW",
107         "nlk_cb_mutex-DNRTMSG",
108         "nlk_cb_mutex-KOBJECT_UEVENT",
109         "nlk_cb_mutex-GENERIC",
110         "nlk_cb_mutex-17",
111         "nlk_cb_mutex-SCSITRANSPORT",
112         "nlk_cb_mutex-ECRYPTFS",
113         "nlk_cb_mutex-RDMA",
114         "nlk_cb_mutex-CRYPTO",
115         "nlk_cb_mutex-SMC",
116         "nlk_cb_mutex-23",
117         "nlk_cb_mutex-24",
118         "nlk_cb_mutex-25",
119         "nlk_cb_mutex-26",
120         "nlk_cb_mutex-27",
121         "nlk_cb_mutex-28",
122         "nlk_cb_mutex-29",
123         "nlk_cb_mutex-30",
124         "nlk_cb_mutex-31",
125         "nlk_cb_mutex-MAX_LINKS"
126 };
127 
128 static int netlink_dump(struct sock *sk);
129 
130 /* nl_table locking explained:
131  * Lookup and traversal are protected with an RCU read-side lock. Insertion
132  * and removal are protected with per bucket lock while using RCU list
133  * modification primitives and may run in parallel to RCU protected lookups.
134  * Destruction of the Netlink socket may only occur *after* nl_table_lock has
135  * been acquired * either during or after the socket has been removed from
136  * the list and after an RCU grace period.
137  */
138 DEFINE_RWLOCK(nl_table_lock);
139 EXPORT_SYMBOL_GPL(nl_table_lock);
140 static atomic_t nl_table_users = ATOMIC_INIT(0);
141 
142 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
143 
144 static BLOCKING_NOTIFIER_HEAD(netlink_chain);
145 
146 
147 static const struct rhashtable_params netlink_rhashtable_params;
148 
149 static inline u32 netlink_group_mask(u32 group)
150 {
151         return group ? 1 << (group - 1) : 0;
152 }
153 
154 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
155                                            gfp_t gfp_mask)
156 {
157         unsigned int len = skb_end_offset(skb);
158         struct sk_buff *new;
159 
160         new = alloc_skb(len, gfp_mask);
161         if (new == NULL)
162                 return NULL;
163 
164         NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
165         NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
166         NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
167 
168         skb_put_data(new, skb->data, len);
169         return new;
170 }
171 
172 static unsigned int netlink_tap_net_id;
173 
174 struct netlink_tap_net {
175         struct list_head netlink_tap_all;
176         struct mutex netlink_tap_lock;
177 };
178 
179 int netlink_add_tap(struct netlink_tap *nt)
180 {
181         struct net *net = dev_net(nt->dev);
182         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
183 
184         if (unlikely(nt->dev->type != ARPHRD_NETLINK))
185                 return -EINVAL;
186 
187         mutex_lock(&nn->netlink_tap_lock);
188         list_add_rcu(&nt->list, &nn->netlink_tap_all);
189         mutex_unlock(&nn->netlink_tap_lock);
190 
191         __module_get(nt->module);
192 
193         return 0;
194 }
195 EXPORT_SYMBOL_GPL(netlink_add_tap);
196 
197 static int __netlink_remove_tap(struct netlink_tap *nt)
198 {
199         struct net *net = dev_net(nt->dev);
200         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
201         bool found = false;
202         struct netlink_tap *tmp;
203 
204         mutex_lock(&nn->netlink_tap_lock);
205 
206         list_for_each_entry(tmp, &nn->netlink_tap_all, list) {
207                 if (nt == tmp) {
208                         list_del_rcu(&nt->list);
209                         found = true;
210                         goto out;
211                 }
212         }
213 
214         pr_warn("__netlink_remove_tap: %p not found\n", nt);
215 out:
216         mutex_unlock(&nn->netlink_tap_lock);
217 
218         if (found)
219                 module_put(nt->module);
220 
221         return found ? 0 : -ENODEV;
222 }
223 
224 int netlink_remove_tap(struct netlink_tap *nt)
225 {
226         int ret;
227 
228         ret = __netlink_remove_tap(nt);
229         synchronize_net();
230 
231         return ret;
232 }
233 EXPORT_SYMBOL_GPL(netlink_remove_tap);
234 
235 static __net_init int netlink_tap_init_net(struct net *net)
236 {
237         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
238 
239         INIT_LIST_HEAD(&nn->netlink_tap_all);
240         mutex_init(&nn->netlink_tap_lock);
241         return 0;
242 }
243 
244 static struct pernet_operations netlink_tap_net_ops = {
245         .init = netlink_tap_init_net,
246         .id   = &netlink_tap_net_id,
247         .size = sizeof(struct netlink_tap_net),
248 };
249 
250 static bool netlink_filter_tap(const struct sk_buff *skb)
251 {
252         struct sock *sk = skb->sk;
253 
254         /* We take the more conservative approach and
255          * whitelist socket protocols that may pass.
256          */
257         switch (sk->sk_protocol) {
258         case NETLINK_ROUTE:
259         case NETLINK_USERSOCK:
260         case NETLINK_SOCK_DIAG:
261         case NETLINK_NFLOG:
262         case NETLINK_XFRM:
263         case NETLINK_FIB_LOOKUP:
264         case NETLINK_NETFILTER:
265         case NETLINK_GENERIC:
266                 return true;
267         }
268 
269         return false;
270 }
271 
272 static int __netlink_deliver_tap_skb(struct sk_buff *skb,
273                                      struct net_device *dev)
274 {
275         struct sk_buff *nskb;
276         struct sock *sk = skb->sk;
277         int ret = -ENOMEM;
278 
279         if (!net_eq(dev_net(dev), sock_net(sk)))
280                 return 0;
281 
282         dev_hold(dev);
283 
284         if (is_vmalloc_addr(skb->head))
285                 nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
286         else
287                 nskb = skb_clone(skb, GFP_ATOMIC);
288         if (nskb) {
289                 nskb->dev = dev;
290                 nskb->protocol = htons((u16) sk->sk_protocol);
291                 nskb->pkt_type = netlink_is_kernel(sk) ?
292                                  PACKET_KERNEL : PACKET_USER;
293                 skb_reset_network_header(nskb);
294                 ret = dev_queue_xmit(nskb);
295                 if (unlikely(ret > 0))
296                         ret = net_xmit_errno(ret);
297         }
298 
299         dev_put(dev);
300         return ret;
301 }
302 
303 static void __netlink_deliver_tap(struct sk_buff *skb, struct netlink_tap_net *nn)
304 {
305         int ret;
306         struct netlink_tap *tmp;
307 
308         if (!netlink_filter_tap(skb))
309                 return;
310 
311         list_for_each_entry_rcu(tmp, &nn->netlink_tap_all, list) {
312                 ret = __netlink_deliver_tap_skb(skb, tmp->dev);
313                 if (unlikely(ret))
314                         break;
315         }
316 }
317 
318 static void netlink_deliver_tap(struct net *net, struct sk_buff *skb)
319 {
320         struct netlink_tap_net *nn = net_generic(net, netlink_tap_net_id);
321 
322         rcu_read_lock();
323 
324         if (unlikely(!list_empty(&nn->netlink_tap_all)))
325                 __netlink_deliver_tap(skb, nn);
326 
327         rcu_read_unlock();
328 }
329 
330 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
331                                        struct sk_buff *skb)
332 {
333         if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
334                 netlink_deliver_tap(sock_net(dst), skb);
335 }
336 
337 static void netlink_overrun(struct sock *sk)
338 {
339         struct netlink_sock *nlk = nlk_sk(sk);
340 
341         if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
342                 if (!test_and_set_bit(NETLINK_S_CONGESTED,
343                                       &nlk_sk(sk)->state)) {
344                         sk->sk_err = ENOBUFS;
345                         sk->sk_error_report(sk);
346                 }
347         }
348         atomic_inc(&sk->sk_drops);
349 }
350 
351 static void netlink_rcv_wake(struct sock *sk)
352 {
353         struct netlink_sock *nlk = nlk_sk(sk);
354 
355         if (skb_queue_empty(&sk->sk_receive_queue))
356                 clear_bit(NETLINK_S_CONGESTED, &nlk->state);
357         if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
358                 wake_up_interruptible(&nlk->wait);
359 }
360 
361 static void netlink_skb_destructor(struct sk_buff *skb)
362 {
363         if (is_vmalloc_addr(skb->head)) {
364                 if (!skb->cloned ||
365                     !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
366                         vfree(skb->head);
367 
368                 skb->head = NULL;
369         }
370         if (skb->sk != NULL)
371                 sock_rfree(skb);
372 }
373 
374 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
375 {
376         WARN_ON(skb->sk != NULL);
377         skb->sk = sk;
378         skb->destructor = netlink_skb_destructor;
379         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
380         sk_mem_charge(sk, skb->truesize);
381 }
382 
383 static void netlink_sock_destruct(struct sock *sk)
384 {
385         struct netlink_sock *nlk = nlk_sk(sk);
386 
387         if (nlk->cb_running) {
388                 if (nlk->cb.done)
389                         nlk->cb.done(&nlk->cb);
390                 module_put(nlk->cb.module);
391                 kfree_skb(nlk->cb.skb);
392         }
393 
394         skb_queue_purge(&sk->sk_receive_queue);
395 
396         if (!sock_flag(sk, SOCK_DEAD)) {
397                 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
398                 return;
399         }
400 
401         WARN_ON(atomic_read(&sk->sk_rmem_alloc));
402         WARN_ON(refcount_read(&sk->sk_wmem_alloc));
403         WARN_ON(nlk_sk(sk)->groups);
404 }
405 
406 static void netlink_sock_destruct_work(struct work_struct *work)
407 {
408         struct netlink_sock *nlk = container_of(work, struct netlink_sock,
409                                                 work);
410 
411         sk_free(&nlk->sk);
412 }
413 
414 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
415  * SMP. Look, when several writers sleep and reader wakes them up, all but one
416  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
417  * this, _but_ remember, it adds useless work on UP machines.
418  */
419 
420 void netlink_table_grab(void)
421         __acquires(nl_table_lock)
422 {
423         might_sleep();
424 
425         write_lock_irq(&nl_table_lock);
426 
427         if (atomic_read(&nl_table_users)) {
428                 DECLARE_WAITQUEUE(wait, current);
429 
430                 add_wait_queue_exclusive(&nl_table_wait, &wait);
431                 for (;;) {
432                         set_current_state(TASK_UNINTERRUPTIBLE);
433                         if (atomic_read(&nl_table_users) == 0)
434                                 break;
435                         write_unlock_irq(&nl_table_lock);
436                         schedule();
437                         write_lock_irq(&nl_table_lock);
438                 }
439 
440                 __set_current_state(TASK_RUNNING);
441                 remove_wait_queue(&nl_table_wait, &wait);
442         }
443 }
444 
445 void netlink_table_ungrab(void)
446         __releases(nl_table_lock)
447 {
448         write_unlock_irq(&nl_table_lock);
449         wake_up(&nl_table_wait);
450 }
451 
452 static inline void
453 netlink_lock_table(void)
454 {
455         /* read_lock() synchronizes us to netlink_table_grab */
456 
457         read_lock(&nl_table_lock);
458         atomic_inc(&nl_table_users);
459         read_unlock(&nl_table_lock);
460 }
461 
462 static inline void
463 netlink_unlock_table(void)
464 {
465         if (atomic_dec_and_test(&nl_table_users))
466                 wake_up(&nl_table_wait);
467 }
468 
469 struct netlink_compare_arg
470 {
471         possible_net_t pnet;
472         u32 portid;
473 };
474 
475 /* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
476 #define netlink_compare_arg_len \
477         (offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
478 
479 static inline int netlink_compare(struct rhashtable_compare_arg *arg,
480                                   const void *ptr)
481 {
482         const struct netlink_compare_arg *x = arg->key;
483         const struct netlink_sock *nlk = ptr;
484 
485         return nlk->portid != x->portid ||
486                !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
487 }
488 
489 static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
490                                      struct net *net, u32 portid)
491 {
492         memset(arg, 0, sizeof(*arg));
493         write_pnet(&arg->pnet, net);
494         arg->portid = portid;
495 }
496 
497 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
498                                      struct net *net)
499 {
500         struct netlink_compare_arg arg;
501 
502         netlink_compare_arg_init(&arg, net, portid);
503         return rhashtable_lookup_fast(&table->hash, &arg,
504                                       netlink_rhashtable_params);
505 }
506 
507 static int __netlink_insert(struct netlink_table *table, struct sock *sk)
508 {
509         struct netlink_compare_arg arg;
510 
511         netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
512         return rhashtable_lookup_insert_key(&table->hash, &arg,
513                                             &nlk_sk(sk)->node,
514                                             netlink_rhashtable_params);
515 }
516 
517 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
518 {
519         struct netlink_table *table = &nl_table[protocol];
520         struct sock *sk;
521 
522         rcu_read_lock();
523         sk = __netlink_lookup(table, portid, net);
524         if (sk)
525                 sock_hold(sk);
526         rcu_read_unlock();
527 
528         return sk;
529 }
530 
531 static const struct proto_ops netlink_ops;
532 
533 static void
534 netlink_update_listeners(struct sock *sk)
535 {
536         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
537         unsigned long mask;
538         unsigned int i;
539         struct listeners *listeners;
540 
541         listeners = nl_deref_protected(tbl->listeners);
542         if (!listeners)
543                 return;
544 
545         for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
546                 mask = 0;
547                 sk_for_each_bound(sk, &tbl->mc_list) {
548                         if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
549                                 mask |= nlk_sk(sk)->groups[i];
550                 }
551                 listeners->masks[i] = mask;
552         }
553         /* this function is only called with the netlink table "grabbed", which
554          * makes sure updates are visible before bind or setsockopt return. */
555 }
556 
557 static int netlink_insert(struct sock *sk, u32 portid)
558 {
559         struct netlink_table *table = &nl_table[sk->sk_protocol];
560         int err;
561 
562         lock_sock(sk);
563 
564         err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
565         if (nlk_sk(sk)->bound)
566                 goto err;
567 
568         nlk_sk(sk)->portid = portid;
569         sock_hold(sk);
570 
571         err = __netlink_insert(table, sk);
572         if (err) {
573                 /* In case the hashtable backend returns with -EBUSY
574                  * from here, it must not escape to the caller.
575                  */
576                 if (unlikely(err == -EBUSY))
577                         err = -EOVERFLOW;
578                 if (err == -EEXIST)
579                         err = -EADDRINUSE;
580                 sock_put(sk);
581                 goto err;
582         }
583 
584         /* We need to ensure that the socket is hashed and visible. */
585         smp_wmb();
586         nlk_sk(sk)->bound = portid;
587 
588 err:
589         release_sock(sk);
590         return err;
591 }
592 
593 static void netlink_remove(struct sock *sk)
594 {
595         struct netlink_table *table;
596 
597         table = &nl_table[sk->sk_protocol];
598         if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
599                                     netlink_rhashtable_params)) {
600                 WARN_ON(refcount_read(&sk->sk_refcnt) == 1);
601                 __sock_put(sk);
602         }
603 
604         netlink_table_grab();
605         if (nlk_sk(sk)->subscriptions) {
606                 __sk_del_bind_node(sk);
607                 netlink_update_listeners(sk);
608         }
609         if (sk->sk_protocol == NETLINK_GENERIC)
610                 atomic_inc(&genl_sk_destructing_cnt);
611         netlink_table_ungrab();
612 }
613 
614 static struct proto netlink_proto = {
615         .name     = "NETLINK",
616         .owner    = THIS_MODULE,
617         .obj_size = sizeof(struct netlink_sock),
618 };
619 
620 static int __netlink_create(struct net *net, struct socket *sock,
621                             struct mutex *cb_mutex, int protocol,
622                             int kern)
623 {
624         struct sock *sk;
625         struct netlink_sock *nlk;
626 
627         sock->ops = &netlink_ops;
628 
629         sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
630         if (!sk)
631                 return -ENOMEM;
632 
633         sock_init_data(sock, sk);
634 
635         nlk = nlk_sk(sk);
636         if (cb_mutex) {
637                 nlk->cb_mutex = cb_mutex;
638         } else {
639                 nlk->cb_mutex = &nlk->cb_def_mutex;
640                 mutex_init(nlk->cb_mutex);
641                 lockdep_set_class_and_name(nlk->cb_mutex,
642                                            nlk_cb_mutex_keys + protocol,
643                                            nlk_cb_mutex_key_strings[protocol]);
644         }
645         init_waitqueue_head(&nlk->wait);
646 
647         sk->sk_destruct = netlink_sock_destruct;
648         sk->sk_protocol = protocol;
649         return 0;
650 }
651 
652 static int netlink_create(struct net *net, struct socket *sock, int protocol,
653                           int kern)
654 {
655         struct module *module = NULL;
656         struct mutex *cb_mutex;
657         struct netlink_sock *nlk;
658         int (*bind)(struct net *net, int group);
659         void (*unbind)(struct net *net, int group);
660         int err = 0;
661 
662         sock->state = SS_UNCONNECTED;
663 
664         if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
665                 return -ESOCKTNOSUPPORT;
666 
667         if (protocol < 0 || protocol >= MAX_LINKS)
668                 return -EPROTONOSUPPORT;
669         protocol = array_index_nospec(protocol, MAX_LINKS);
670 
671         netlink_lock_table();
672 #ifdef CONFIG_MODULES
673         if (!nl_table[protocol].registered) {
674                 netlink_unlock_table();
675                 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
676                 netlink_lock_table();
677         }
678 #endif
679         if (nl_table[protocol].registered &&
680             try_module_get(nl_table[protocol].module))
681                 module = nl_table[protocol].module;
682         else
683                 err = -EPROTONOSUPPORT;
684         cb_mutex = nl_table[protocol].cb_mutex;
685         bind = nl_table[protocol].bind;
686         unbind = nl_table[protocol].unbind;
687         netlink_unlock_table();
688 
689         if (err < 0)
690                 goto out;
691 
692         err = __netlink_create(net, sock, cb_mutex, protocol, kern);
693         if (err < 0)
694                 goto out_module;
695 
696         local_bh_disable();
697         sock_prot_inuse_add(net, &netlink_proto, 1);
698         local_bh_enable();
699 
700         nlk = nlk_sk(sock->sk);
701         nlk->module = module;
702         nlk->netlink_bind = bind;
703         nlk->netlink_unbind = unbind;
704 out:
705         return err;
706 
707 out_module:
708         module_put(module);
709         goto out;
710 }
711 
712 static void deferred_put_nlk_sk(struct rcu_head *head)
713 {
714         struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
715         struct sock *sk = &nlk->sk;
716 
717         kfree(nlk->groups);
718         nlk->groups = NULL;
719 
720         if (!refcount_dec_and_test(&sk->sk_refcnt))
721                 return;
722 
723         if (nlk->cb_running && nlk->cb.done) {
724                 INIT_WORK(&nlk->work, netlink_sock_destruct_work);
725                 schedule_work(&nlk->work);
726                 return;
727         }
728 
729         sk_free(sk);
730 }
731 
732 static int netlink_release(struct socket *sock)
733 {
734         struct sock *sk = sock->sk;
735         struct netlink_sock *nlk;
736 
737         if (!sk)
738                 return 0;
739 
740         netlink_remove(sk);
741         sock_orphan(sk);
742         nlk = nlk_sk(sk);
743 
744         /*
745          * OK. Socket is unlinked, any packets that arrive now
746          * will be purged.
747          */
748 
749         /* must not acquire netlink_table_lock in any way again before unbind
750          * and notifying genetlink is done as otherwise it might deadlock
751          */
752         if (nlk->netlink_unbind) {
753                 int i;
754 
755                 for (i = 0; i < nlk->ngroups; i++)
756                         if (test_bit(i, nlk->groups))
757                                 nlk->netlink_unbind(sock_net(sk), i + 1);
758         }
759         if (sk->sk_protocol == NETLINK_GENERIC &&
760             atomic_dec_return(&genl_sk_destructing_cnt) == 0)
761                 wake_up(&genl_sk_destructing_waitq);
762 
763         sock->sk = NULL;
764         wake_up_interruptible_all(&nlk->wait);
765 
766         skb_queue_purge(&sk->sk_write_queue);
767 
768         if (nlk->portid && nlk->bound) {
769                 struct netlink_notify n = {
770                                                 .net = sock_net(sk),
771                                                 .protocol = sk->sk_protocol,
772                                                 .portid = nlk->portid,
773                                           };
774                 blocking_notifier_call_chain(&netlink_chain,
775                                 NETLINK_URELEASE, &n);
776         }
777 
778         module_put(nlk->module);
779 
780         if (netlink_is_kernel(sk)) {
781                 netlink_table_grab();
782                 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
783                 if (--nl_table[sk->sk_protocol].registered == 0) {
784                         struct listeners *old;
785 
786                         old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
787                         RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
788                         kfree_rcu(old, rcu);
789                         nl_table[sk->sk_protocol].module = NULL;
790                         nl_table[sk->sk_protocol].bind = NULL;
791                         nl_table[sk->sk_protocol].unbind = NULL;
792                         nl_table[sk->sk_protocol].flags = 0;
793                         nl_table[sk->sk_protocol].registered = 0;
794                 }
795                 netlink_table_ungrab();
796         }
797 
798         local_bh_disable();
799         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
800         local_bh_enable();
801         call_rcu(&nlk->rcu, deferred_put_nlk_sk);
802         return 0;
803 }
804 
805 static int netlink_autobind(struct socket *sock)
806 {
807         struct sock *sk = sock->sk;
808         struct net *net = sock_net(sk);
809         struct netlink_table *table = &nl_table[sk->sk_protocol];
810         s32 portid = task_tgid_vnr(current);
811         int err;
812         s32 rover = -4096;
813         bool ok;
814 
815 retry:
816         cond_resched();
817         rcu_read_lock();
818         ok = !__netlink_lookup(table, portid, net);
819         rcu_read_unlock();
820         if (!ok) {
821                 /* Bind collision, search negative portid values. */
822                 if (rover == -4096)
823                         /* rover will be in range [S32_MIN, -4097] */
824                         rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
825                 else if (rover >= -4096)
826                         rover = -4097;
827                 portid = rover--;
828                 goto retry;
829         }
830 
831         err = netlink_insert(sk, portid);
832         if (err == -EADDRINUSE)
833                 goto retry;
834 
835         /* If 2 threads race to autobind, that is fine.  */
836         if (err == -EBUSY)
837                 err = 0;
838 
839         return err;
840 }
841 
842 /**
843  * __netlink_ns_capable - General netlink message capability test
844  * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
845  * @user_ns: The user namespace of the capability to use
846  * @cap: The capability to use
847  *
848  * Test to see if the opener of the socket we received the message
849  * from had when the netlink socket was created and the sender of the
850  * message has has the capability @cap in the user namespace @user_ns.
851  */
852 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
853                         struct user_namespace *user_ns, int cap)
854 {
855         return ((nsp->flags & NETLINK_SKB_DST) ||
856                 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
857                 ns_capable(user_ns, cap);
858 }
859 EXPORT_SYMBOL(__netlink_ns_capable);
860 
861 /**
862  * netlink_ns_capable - General netlink message capability test
863  * @skb: socket buffer holding a netlink command from userspace
864  * @user_ns: The user namespace of the capability to use
865  * @cap: The capability to use
866  *
867  * Test to see if the opener of the socket we received the message
868  * from had when the netlink socket was created and the sender of the
869  * message has has the capability @cap in the user namespace @user_ns.
870  */
871 bool netlink_ns_capable(const struct sk_buff *skb,
872                         struct user_namespace *user_ns, int cap)
873 {
874         return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
875 }
876 EXPORT_SYMBOL(netlink_ns_capable);
877 
878 /**
879  * netlink_capable - Netlink global message capability test
880  * @skb: socket buffer holding a netlink command from userspace
881  * @cap: The capability to use
882  *
883  * Test to see if the opener of the socket we received the message
884  * from had when the netlink socket was created and the sender of the
885  * message has has the capability @cap in all user namespaces.
886  */
887 bool netlink_capable(const struct sk_buff *skb, int cap)
888 {
889         return netlink_ns_capable(skb, &init_user_ns, cap);
890 }
891 EXPORT_SYMBOL(netlink_capable);
892 
893 /**
894  * netlink_net_capable - Netlink network namespace message capability test
895  * @skb: socket buffer holding a netlink command from userspace
896  * @cap: The capability to use
897  *
898  * Test to see if the opener of the socket we received the message
899  * from had when the netlink socket was created and the sender of the
900  * message has has the capability @cap over the network namespace of
901  * the socket we received the message from.
902  */
903 bool netlink_net_capable(const struct sk_buff *skb, int cap)
904 {
905         return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
906 }
907 EXPORT_SYMBOL(netlink_net_capable);
908 
909 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
910 {
911         return (nl_table[sock->sk->sk_protocol].flags & flag) ||
912                 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
913 }
914 
915 static void
916 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
917 {
918         struct netlink_sock *nlk = nlk_sk(sk);
919 
920         if (nlk->subscriptions && !subscriptions)
921                 __sk_del_bind_node(sk);
922         else if (!nlk->subscriptions && subscriptions)
923                 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
924         nlk->subscriptions = subscriptions;
925 }
926 
927 static int netlink_realloc_groups(struct sock *sk)
928 {
929         struct netlink_sock *nlk = nlk_sk(sk);
930         unsigned int groups;
931         unsigned long *new_groups;
932         int err = 0;
933 
934         netlink_table_grab();
935 
936         groups = nl_table[sk->sk_protocol].groups;
937         if (!nl_table[sk->sk_protocol].registered) {
938                 err = -ENOENT;
939                 goto out_unlock;
940         }
941 
942         if (nlk->ngroups >= groups)
943                 goto out_unlock;
944 
945         new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
946         if (new_groups == NULL) {
947                 err = -ENOMEM;
948                 goto out_unlock;
949         }
950         memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
951                NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
952 
953         nlk->groups = new_groups;
954         nlk->ngroups = groups;
955  out_unlock:
956         netlink_table_ungrab();
957         return err;
958 }
959 
960 static void netlink_undo_bind(int group, long unsigned int groups,
961                               struct sock *sk)
962 {
963         struct netlink_sock *nlk = nlk_sk(sk);
964         int undo;
965 
966         if (!nlk->netlink_unbind)
967                 return;
968 
969         for (undo = 0; undo < group; undo++)
970                 if (test_bit(undo, &groups))
971                         nlk->netlink_unbind(sock_net(sk), undo + 1);
972 }
973 
974 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
975                         int addr_len)
976 {
977         struct sock *sk = sock->sk;
978         struct net *net = sock_net(sk);
979         struct netlink_sock *nlk = nlk_sk(sk);
980         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
981         int err = 0;
982         unsigned long groups;
983         bool bound;
984 
985         if (addr_len < sizeof(struct sockaddr_nl))
986                 return -EINVAL;
987 
988         if (nladdr->nl_family != AF_NETLINK)
989                 return -EINVAL;
990         groups = nladdr->nl_groups;
991 
992         /* Only superuser is allowed to listen multicasts */
993         if (groups) {
994                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
995                         return -EPERM;
996                 err = netlink_realloc_groups(sk);
997                 if (err)
998                         return err;
999         }
1000 
1001         if (nlk->ngroups < BITS_PER_LONG)
1002                 groups &= (1UL << nlk->ngroups) - 1;
1003 
1004         bound = nlk->bound;
1005         if (bound) {
1006                 /* Ensure nlk->portid is up-to-date. */
1007                 smp_rmb();
1008 
1009                 if (nladdr->nl_pid != nlk->portid)
1010                         return -EINVAL;
1011         }
1012 
1013         netlink_lock_table();
1014         if (nlk->netlink_bind && groups) {
1015                 int group;
1016 
1017                 for (group = 0; group < nlk->ngroups; group++) {
1018                         if (!test_bit(group, &groups))
1019                                 continue;
1020                         err = nlk->netlink_bind(net, group + 1);
1021                         if (!err)
1022                                 continue;
1023                         netlink_undo_bind(group, groups, sk);
1024                         goto unlock;
1025                 }
1026         }
1027 
1028         /* No need for barriers here as we return to user-space without
1029          * using any of the bound attributes.
1030          */
1031         if (!bound) {
1032                 err = nladdr->nl_pid ?
1033                         netlink_insert(sk, nladdr->nl_pid) :
1034                         netlink_autobind(sock);
1035                 if (err) {
1036                         netlink_undo_bind(nlk->ngroups, groups, sk);
1037                         goto unlock;
1038                 }
1039         }
1040 
1041         if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
1042                 goto unlock;
1043         netlink_unlock_table();
1044 
1045         netlink_table_grab();
1046         netlink_update_subscriptions(sk, nlk->subscriptions +
1047                                          hweight32(groups) -
1048                                          hweight32(nlk->groups[0]));
1049         nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
1050         netlink_update_listeners(sk);
1051         netlink_table_ungrab();
1052 
1053         return 0;
1054 
1055 unlock:
1056         netlink_unlock_table();
1057         return err;
1058 }
1059 
1060 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
1061                            int alen, int flags)
1062 {
1063         int err = 0;
1064         struct sock *sk = sock->sk;
1065         struct netlink_sock *nlk = nlk_sk(sk);
1066         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
1067 
1068         if (alen < sizeof(addr->sa_family))
1069                 return -EINVAL;
1070 
1071         if (addr->sa_family == AF_UNSPEC) {
1072                 sk->sk_state    = NETLINK_UNCONNECTED;
1073                 nlk->dst_portid = 0;
1074                 nlk->dst_group  = 0;
1075                 return 0;
1076         }
1077         if (addr->sa_family != AF_NETLINK)
1078                 return -EINVAL;
1079 
1080         if (alen < sizeof(struct sockaddr_nl))
1081                 return -EINVAL;
1082 
1083         if ((nladdr->nl_groups || nladdr->nl_pid) &&
1084             !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1085                 return -EPERM;
1086 
1087         /* No need for barriers here as we return to user-space without
1088          * using any of the bound attributes.
1089          */
1090         if (!nlk->bound)
1091                 err = netlink_autobind(sock);
1092 
1093         if (err == 0) {
1094                 sk->sk_state    = NETLINK_CONNECTED;
1095                 nlk->dst_portid = nladdr->nl_pid;
1096                 nlk->dst_group  = ffs(nladdr->nl_groups);
1097         }
1098 
1099         return err;
1100 }
1101 
1102 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1103                            int peer)
1104 {
1105         struct sock *sk = sock->sk;
1106         struct netlink_sock *nlk = nlk_sk(sk);
1107         DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1108 
1109         nladdr->nl_family = AF_NETLINK;
1110         nladdr->nl_pad = 0;
1111 
1112         if (peer) {
1113                 nladdr->nl_pid = nlk->dst_portid;
1114                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
1115         } else {
1116                 nladdr->nl_pid = nlk->portid;
1117                 netlink_lock_table();
1118                 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1119                 netlink_unlock_table();
1120         }
1121         return sizeof(*nladdr);
1122 }
1123 
1124 static int netlink_ioctl(struct socket *sock, unsigned int cmd,
1125                          unsigned long arg)
1126 {
1127         /* try to hand this ioctl down to the NIC drivers.
1128          */
1129         return -ENOIOCTLCMD;
1130 }
1131 
1132 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1133 {
1134         struct sock *sock;
1135         struct netlink_sock *nlk;
1136 
1137         sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1138         if (!sock)
1139                 return ERR_PTR(-ECONNREFUSED);
1140 
1141         /* Don't bother queuing skb if kernel socket has no input function */
1142         nlk = nlk_sk(sock);
1143         if (sock->sk_state == NETLINK_CONNECTED &&
1144             nlk->dst_portid != nlk_sk(ssk)->portid) {
1145                 sock_put(sock);
1146                 return ERR_PTR(-ECONNREFUSED);
1147         }
1148         return sock;
1149 }
1150 
1151 struct sock *netlink_getsockbyfilp(struct file *filp)
1152 {
1153         struct inode *inode = file_inode(filp);
1154         struct sock *sock;
1155 
1156         if (!S_ISSOCK(inode->i_mode))
1157                 return ERR_PTR(-ENOTSOCK);
1158 
1159         sock = SOCKET_I(inode)->sk;
1160         if (sock->sk_family != AF_NETLINK)
1161                 return ERR_PTR(-EINVAL);
1162 
1163         sock_hold(sock);
1164         return sock;
1165 }
1166 
1167 static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
1168                                                int broadcast)
1169 {
1170         struct sk_buff *skb;
1171         void *data;
1172 
1173         if (size <= NLMSG_GOODSIZE || broadcast)
1174                 return alloc_skb(size, GFP_KERNEL);
1175 
1176         size = SKB_DATA_ALIGN(size) +
1177                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1178 
1179         data = vmalloc(size);
1180         if (data == NULL)
1181                 return NULL;
1182 
1183         skb = __build_skb(data, size);
1184         if (skb == NULL)
1185                 vfree(data);
1186         else
1187                 skb->destructor = netlink_skb_destructor;
1188 
1189         return skb;
1190 }
1191 
1192 /*
1193  * Attach a skb to a netlink socket.
1194  * The caller must hold a reference to the destination socket. On error, the
1195  * reference is dropped. The skb is not send to the destination, just all
1196  * all error checks are performed and memory in the queue is reserved.
1197  * Return values:
1198  * < 0: error. skb freed, reference to sock dropped.
1199  * 0: continue
1200  * 1: repeat lookup - reference dropped while waiting for socket memory.
1201  */
1202 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1203                       long *timeo, struct sock *ssk)
1204 {
1205         struct netlink_sock *nlk;
1206 
1207         nlk = nlk_sk(sk);
1208 
1209         if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1210              test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
1211                 DECLARE_WAITQUEUE(wait, current);
1212                 if (!*timeo) {
1213                         if (!ssk || netlink_is_kernel(ssk))
1214                                 netlink_overrun(sk);
1215                         sock_put(sk);
1216                         kfree_skb(skb);
1217                         return -EAGAIN;
1218                 }
1219 
1220                 __set_current_state(TASK_INTERRUPTIBLE);
1221                 add_wait_queue(&nlk->wait, &wait);
1222 
1223                 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1224                      test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
1225                     !sock_flag(sk, SOCK_DEAD))
1226                         *timeo = schedule_timeout(*timeo);
1227 
1228                 __set_current_state(TASK_RUNNING);
1229                 remove_wait_queue(&nlk->wait, &wait);
1230                 sock_put(sk);
1231 
1232                 if (signal_pending(current)) {
1233                         kfree_skb(skb);
1234                         return sock_intr_errno(*timeo);
1235                 }
1236                 return 1;
1237         }
1238         netlink_skb_set_owner_r(skb, sk);
1239         return 0;
1240 }
1241 
1242 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1243 {
1244         int len = skb->len;
1245 
1246         netlink_deliver_tap(sock_net(sk), skb);
1247 
1248         skb_queue_tail(&sk->sk_receive_queue, skb);
1249         sk->sk_data_ready(sk);
1250         return len;
1251 }
1252 
1253 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1254 {
1255         int len = __netlink_sendskb(sk, skb);
1256 
1257         sock_put(sk);
1258         return len;
1259 }
1260 
1261 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1262 {
1263         kfree_skb(skb);
1264         sock_put(sk);
1265 }
1266 
1267 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1268 {
1269         int delta;
1270 
1271         WARN_ON(skb->sk != NULL);
1272         delta = skb->end - skb->tail;
1273         if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
1274                 return skb;
1275 
1276         if (skb_shared(skb)) {
1277                 struct sk_buff *nskb = skb_clone(skb, allocation);
1278                 if (!nskb)
1279                         return skb;
1280                 consume_skb(skb);
1281                 skb = nskb;
1282         }
1283 
1284         pskb_expand_head(skb, 0, -delta,
1285                          (allocation & ~__GFP_DIRECT_RECLAIM) |
1286                          __GFP_NOWARN | __GFP_NORETRY);
1287         return skb;
1288 }
1289 
1290 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1291                                   struct sock *ssk)
1292 {
1293         int ret;
1294         struct netlink_sock *nlk = nlk_sk(sk);
1295 
1296         ret = -ECONNREFUSED;
1297         if (nlk->netlink_rcv != NULL) {
1298                 ret = skb->len;
1299                 netlink_skb_set_owner_r(skb, sk);
1300                 NETLINK_CB(skb).sk = ssk;
1301                 netlink_deliver_tap_kernel(sk, ssk, skb);
1302                 nlk->netlink_rcv(skb);
1303                 consume_skb(skb);
1304         } else {
1305                 kfree_skb(skb);
1306         }
1307         sock_put(sk);
1308         return ret;
1309 }
1310 
1311 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1312                     u32 portid, int nonblock)
1313 {
1314         struct sock *sk;
1315         int err;
1316         long timeo;
1317 
1318         skb = netlink_trim(skb, gfp_any());
1319 
1320         timeo = sock_sndtimeo(ssk, nonblock);
1321 retry:
1322         sk = netlink_getsockbyportid(ssk, portid);
1323         if (IS_ERR(sk)) {
1324                 kfree_skb(skb);
1325                 return PTR_ERR(sk);
1326         }
1327         if (netlink_is_kernel(sk))
1328                 return netlink_unicast_kernel(sk, skb, ssk);
1329 
1330         if (sk_filter(sk, skb)) {
1331                 err = skb->len;
1332                 kfree_skb(skb);
1333                 sock_put(sk);
1334                 return err;
1335         }
1336 
1337         err = netlink_attachskb(sk, skb, &timeo, ssk);
1338         if (err == 1)
1339                 goto retry;
1340         if (err)
1341                 return err;
1342 
1343         return netlink_sendskb(sk, skb);
1344 }
1345 EXPORT_SYMBOL(netlink_unicast);
1346 
1347 int netlink_has_listeners(struct sock *sk, unsigned int group)
1348 {
1349         int res = 0;
1350         struct listeners *listeners;
1351 
1352         BUG_ON(!netlink_is_kernel(sk));
1353 
1354         rcu_read_lock();
1355         listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1356 
1357         if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1358                 res = test_bit(group - 1, listeners->masks);
1359 
1360         rcu_read_unlock();
1361 
1362         return res;
1363 }
1364 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1365 
1366 bool netlink_strict_get_check(struct sk_buff *skb)
1367 {
1368         const struct netlink_sock *nlk = nlk_sk(NETLINK_CB(skb).sk);
1369 
1370         return nlk->flags & NETLINK_F_STRICT_CHK;
1371 }
1372 EXPORT_SYMBOL_GPL(netlink_strict_get_check);
1373 
1374 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1375 {
1376         struct netlink_sock *nlk = nlk_sk(sk);
1377 
1378         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1379             !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
1380                 netlink_skb_set_owner_r(skb, sk);
1381                 __netlink_sendskb(sk, skb);
1382                 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1383         }
1384         return -1;
1385 }
1386 
1387 struct netlink_broadcast_data {
1388         struct sock *exclude_sk;
1389         struct net *net;
1390         u32 portid;
1391         u32 group;
1392         int failure;
1393         int delivery_failure;
1394         int congested;
1395         int delivered;
1396         gfp_t allocation;
1397         struct sk_buff *skb, *skb2;
1398         int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1399         void *tx_data;
1400 };
1401 
1402 static void do_one_broadcast(struct sock *sk,
1403                                     struct netlink_broadcast_data *p)
1404 {
1405         struct netlink_sock *nlk = nlk_sk(sk);
1406         int val;
1407 
1408         if (p->exclude_sk == sk)
1409                 return;
1410 
1411         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1412             !test_bit(p->group - 1, nlk->groups))
1413                 return;
1414 
1415         if (!net_eq(sock_net(sk), p->net)) {
1416                 if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID))
1417                         return;
1418 
1419                 if (!peernet_has_id(sock_net(sk), p->net))
1420                         return;
1421 
1422                 if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns,
1423                                      CAP_NET_BROADCAST))
1424                         return;
1425         }
1426 
1427         if (p->failure) {
1428                 netlink_overrun(sk);
1429                 return;
1430         }
1431 
1432         sock_hold(sk);
1433         if (p->skb2 == NULL) {
1434                 if (skb_shared(p->skb)) {
1435                         p->skb2 = skb_clone(p->skb, p->allocation);
1436                 } else {
1437                         p->skb2 = skb_get(p->skb);
1438                         /*
1439                          * skb ownership may have been set when
1440                          * delivered to a previous socket.
1441                          */
1442                         skb_orphan(p->skb2);
1443                 }
1444         }
1445         if (p->skb2 == NULL) {
1446                 netlink_overrun(sk);
1447                 /* Clone failed. Notify ALL listeners. */
1448                 p->failure = 1;
1449                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1450                         p->delivery_failure = 1;
1451                 goto out;
1452         }
1453         if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1454                 kfree_skb(p->skb2);
1455                 p->skb2 = NULL;
1456                 goto out;
1457         }
1458         if (sk_filter(sk, p->skb2)) {
1459                 kfree_skb(p->skb2);
1460                 p->skb2 = NULL;
1461                 goto out;
1462         }
1463         NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
1464         if (NETLINK_CB(p->skb2).nsid != NETNSA_NSID_NOT_ASSIGNED)
1465                 NETLINK_CB(p->skb2).nsid_is_set = true;
1466         val = netlink_broadcast_deliver(sk, p->skb2);
1467         if (val < 0) {
1468                 netlink_overrun(sk);
1469                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1470                         p->delivery_failure = 1;
1471         } else {
1472                 p->congested |= val;
1473                 p->delivered = 1;
1474                 p->skb2 = NULL;
1475         }
1476 out:
1477         sock_put(sk);
1478 }
1479 
1480 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid,
1481         u32 group, gfp_t allocation,
1482         int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1483         void *filter_data)
1484 {
1485         struct net *net = sock_net(ssk);
1486         struct netlink_broadcast_data info;
1487         struct sock *sk;
1488 
1489         skb = netlink_trim(skb, allocation);
1490 
1491         info.exclude_sk = ssk;
1492         info.net = net;
1493         info.portid = portid;
1494         info.group = group;
1495         info.failure = 0;
1496         info.delivery_failure = 0;
1497         info.congested = 0;
1498         info.delivered = 0;
1499         info.allocation = allocation;
1500         info.skb = skb;
1501         info.skb2 = NULL;
1502         info.tx_filter = filter;
1503         info.tx_data = filter_data;
1504 
1505         /* While we sleep in clone, do not allow to change socket list */
1506 
1507         netlink_lock_table();
1508 
1509         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1510                 do_one_broadcast(sk, &info);
1511 
1512         consume_skb(skb);
1513 
1514         netlink_unlock_table();
1515 
1516         if (info.delivery_failure) {
1517                 kfree_skb(info.skb2);
1518                 return -ENOBUFS;
1519         }
1520         consume_skb(info.skb2);
1521 
1522         if (info.delivered) {
1523                 if (info.congested && gfpflags_allow_blocking(allocation))
1524                         yield();
1525                 return 0;
1526         }
1527         return -ESRCH;
1528 }
1529 EXPORT_SYMBOL(netlink_broadcast_filtered);
1530 
1531 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
1532                       u32 group, gfp_t allocation)
1533 {
1534         return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
1535                 NULL, NULL);
1536 }
1537 EXPORT_SYMBOL(netlink_broadcast);
1538 
1539 struct netlink_set_err_data {
1540         struct sock *exclude_sk;
1541         u32 portid;
1542         u32 group;
1543         int code;
1544 };
1545 
1546 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1547 {
1548         struct netlink_sock *nlk = nlk_sk(sk);
1549         int ret = 0;
1550 
1551         if (sk == p->exclude_sk)
1552                 goto out;
1553 
1554         if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1555                 goto out;
1556 
1557         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1558             !test_bit(p->group - 1, nlk->groups))
1559                 goto out;
1560 
1561         if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) {
1562                 ret = 1;
1563                 goto out;
1564         }
1565 
1566         sk->sk_err = p->code;
1567         sk->sk_error_report(sk);
1568 out:
1569         return ret;
1570 }
1571 
1572 /**
1573  * netlink_set_err - report error to broadcast listeners
1574  * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1575  * @portid: the PORTID of a process that we want to skip (if any)
1576  * @group: the broadcast group that will notice the error
1577  * @code: error code, must be negative (as usual in kernelspace)
1578  *
1579  * This function returns the number of broadcast listeners that have set the
1580  * NETLINK_NO_ENOBUFS socket option.
1581  */
1582 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
1583 {
1584         struct netlink_set_err_data info;
1585         struct sock *sk;
1586         int ret = 0;
1587 
1588         info.exclude_sk = ssk;
1589         info.portid = portid;
1590         info.group = group;
1591         /* sk->sk_err wants a positive error value */
1592         info.code = -code;
1593 
1594         read_lock(&nl_table_lock);
1595 
1596         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1597                 ret += do_one_set_err(sk, &info);
1598 
1599         read_unlock(&nl_table_lock);
1600         return ret;
1601 }
1602 EXPORT_SYMBOL(netlink_set_err);
1603 
1604 /* must be called with netlink table grabbed */
1605 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1606                                      unsigned int group,
1607                                      int is_new)
1608 {
1609         int old, new = !!is_new, subscriptions;
1610 
1611         old = test_bit(group - 1, nlk->groups);
1612         subscriptions = nlk->subscriptions - old + new;
1613         if (new)
1614                 __set_bit(group - 1, nlk->groups);
1615         else
1616                 __clear_bit(group - 1, nlk->groups);
1617         netlink_update_subscriptions(&nlk->sk, subscriptions);
1618         netlink_update_listeners(&nlk->sk);
1619 }
1620 
1621 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1622                               char __user *optval, unsigned int optlen)
1623 {
1624         struct sock *sk = sock->sk;
1625         struct netlink_sock *nlk = nlk_sk(sk);
1626         unsigned int val = 0;
1627         int err;
1628 
1629         if (level != SOL_NETLINK)
1630                 return -ENOPROTOOPT;
1631 
1632         if (optlen >= sizeof(int) &&
1633             get_user(val, (unsigned int __user *)optval))
1634                 return -EFAULT;
1635 
1636         switch (optname) {
1637         case NETLINK_PKTINFO:
1638                 if (val)
1639                         nlk->flags |= NETLINK_F_RECV_PKTINFO;
1640                 else
1641                         nlk->flags &= ~NETLINK_F_RECV_PKTINFO;
1642                 err = 0;
1643                 break;
1644         case NETLINK_ADD_MEMBERSHIP:
1645         case NETLINK_DROP_MEMBERSHIP: {
1646                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1647                         return -EPERM;
1648                 err = netlink_realloc_groups(sk);
1649                 if (err)
1650                         return err;
1651                 if (!val || val - 1 >= nlk->ngroups)
1652                         return -EINVAL;
1653                 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
1654                         err = nlk->netlink_bind(sock_net(sk), val);
1655                         if (err)
1656                                 return err;
1657                 }
1658                 netlink_table_grab();
1659                 netlink_update_socket_mc(nlk, val,
1660                                          optname == NETLINK_ADD_MEMBERSHIP);
1661                 netlink_table_ungrab();
1662                 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
1663                         nlk->netlink_unbind(sock_net(sk), val);
1664 
1665                 err = 0;
1666                 break;
1667         }
1668         case NETLINK_BROADCAST_ERROR:
1669                 if (val)
1670                         nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR;
1671                 else
1672                         nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR;
1673                 err = 0;
1674                 break;
1675         case NETLINK_NO_ENOBUFS:
1676                 if (val) {
1677                         nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS;
1678                         clear_bit(NETLINK_S_CONGESTED, &nlk->state);
1679                         wake_up_interruptible(&nlk->wait);
1680                 } else {
1681                         nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS;
1682                 }
1683                 err = 0;
1684                 break;
1685         case NETLINK_LISTEN_ALL_NSID:
1686                 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
1687                         return -EPERM;
1688 
1689                 if (val)
1690                         nlk->flags |= NETLINK_F_LISTEN_ALL_NSID;
1691                 else
1692                         nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
1693                 err = 0;
1694                 break;
1695         case NETLINK_CAP_ACK:
1696                 if (val)
1697                         nlk->flags |= NETLINK_F_CAP_ACK;
1698                 else
1699                         nlk->flags &= ~NETLINK_F_CAP_ACK;
1700                 err = 0;
1701                 break;
1702         case NETLINK_EXT_ACK:
1703                 if (val)
1704                         nlk->flags |= NETLINK_F_EXT_ACK;
1705                 else
1706                         nlk->flags &= ~NETLINK_F_EXT_ACK;
1707                 err = 0;
1708                 break;
1709         case NETLINK_GET_STRICT_CHK:
1710                 if (val)
1711                         nlk->flags |= NETLINK_F_STRICT_CHK;
1712                 else
1713                         nlk->flags &= ~NETLINK_F_STRICT_CHK;
1714                 err = 0;
1715                 break;
1716         default:
1717                 err = -ENOPROTOOPT;
1718         }
1719         return err;
1720 }
1721 
1722 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1723                               char __user *optval, int __user *optlen)
1724 {
1725         struct sock *sk = sock->sk;
1726         struct netlink_sock *nlk = nlk_sk(sk);
1727         int len, val, err;
1728 
1729         if (level != SOL_NETLINK)
1730                 return -ENOPROTOOPT;
1731 
1732         if (get_user(len, optlen))
1733                 return -EFAULT;
1734         if (len < 0)
1735                 return -EINVAL;
1736 
1737         switch (optname) {
1738         case NETLINK_PKTINFO:
1739                 if (len < sizeof(int))
1740                         return -EINVAL;
1741                 len = sizeof(int);
1742                 val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0;
1743                 if (put_user(len, optlen) ||
1744                     put_user(val, optval))
1745                         return -EFAULT;
1746                 err = 0;
1747                 break;
1748         case NETLINK_BROADCAST_ERROR:
1749                 if (len < sizeof(int))
1750                         return -EINVAL;
1751                 len = sizeof(int);
1752                 val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0;
1753                 if (put_user(len, optlen) ||
1754                     put_user(val, optval))
1755                         return -EFAULT;
1756                 err = 0;
1757                 break;
1758         case NETLINK_NO_ENOBUFS:
1759                 if (len < sizeof(int))
1760                         return -EINVAL;
1761                 len = sizeof(int);
1762                 val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0;
1763                 if (put_user(len, optlen) ||
1764                     put_user(val, optval))
1765                         return -EFAULT;
1766                 err = 0;
1767                 break;
1768         case NETLINK_LIST_MEMBERSHIPS: {
1769                 int pos, idx, shift;
1770 
1771                 err = 0;
1772                 netlink_lock_table();
1773                 for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
1774                         if (len - pos < sizeof(u32))
1775                                 break;
1776 
1777                         idx = pos / sizeof(unsigned long);
1778                         shift = (pos % sizeof(unsigned long)) * 8;
1779                         if (put_user((u32)(nlk->groups[idx] >> shift),
1780                                      (u32 __user *)(optval + pos))) {
1781                                 err = -EFAULT;
1782                                 break;
1783                         }
1784                 }
1785                 if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
1786                         err = -EFAULT;
1787                 netlink_unlock_table();
1788                 break;
1789         }
1790         case NETLINK_CAP_ACK:
1791                 if (len < sizeof(int))
1792                         return -EINVAL;
1793                 len = sizeof(int);
1794                 val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0;
1795                 if (put_user(len, optlen) ||
1796                     put_user(val, optval))
1797                         return -EFAULT;
1798                 err = 0;
1799                 break;
1800         case NETLINK_EXT_ACK:
1801                 if (len < sizeof(int))
1802                         return -EINVAL;
1803                 len = sizeof(int);
1804                 val = nlk->flags & NETLINK_F_EXT_ACK ? 1 : 0;
1805                 if (put_user(len, optlen) || put_user(val, optval))
1806                         return -EFAULT;
1807                 err = 0;
1808                 break;
1809         case NETLINK_GET_STRICT_CHK:
1810                 if (len < sizeof(int))
1811                         return -EINVAL;
1812                 len = sizeof(int);
1813                 val = nlk->flags & NETLINK_F_STRICT_CHK ? 1 : 0;
1814                 if (put_user(len, optlen) || put_user(val, optval))
1815                         return -EFAULT;
1816                 err = 0;
1817                 break;
1818         default:
1819                 err = -ENOPROTOOPT;
1820         }
1821         return err;
1822 }
1823 
1824 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1825 {
1826         struct nl_pktinfo info;
1827 
1828         info.group = NETLINK_CB(skb).dst_group;
1829         put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1830 }
1831 
1832 static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg,
1833                                          struct sk_buff *skb)
1834 {
1835         if (!NETLINK_CB(skb).nsid_is_set)
1836                 return;
1837 
1838         put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int),
1839                  &NETLINK_CB(skb).nsid);
1840 }
1841 
1842 static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
1843 {
1844         struct sock *sk = sock->sk;
1845         struct netlink_sock *nlk = nlk_sk(sk);
1846         DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1847         u32 dst_portid;
1848         u32 dst_group;
1849         struct sk_buff *skb;
1850         int err;
1851         struct scm_cookie scm;
1852         u32 netlink_skb_flags = 0;
1853 
1854         if (msg->msg_flags&MSG_OOB)
1855                 return -EOPNOTSUPP;
1856 
1857         err = scm_send(sock, msg, &scm, true);
1858         if (err < 0)
1859                 return err;
1860 
1861         if (msg->msg_namelen) {
1862                 err = -EINVAL;
1863                 if (msg->msg_namelen < sizeof(struct sockaddr_nl))
1864                         goto out;
1865                 if (addr->nl_family != AF_NETLINK)
1866                         goto out;
1867                 dst_portid = addr->nl_pid;
1868                 dst_group = ffs(addr->nl_groups);
1869                 err =  -EPERM;
1870                 if ((dst_group || dst_portid) &&
1871                     !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1872                         goto out;
1873                 netlink_skb_flags |= NETLINK_SKB_DST;
1874         } else {
1875                 dst_portid = nlk->dst_portid;
1876                 dst_group = nlk->dst_group;
1877         }
1878 
1879         if (!nlk->bound) {
1880                 err = netlink_autobind(sock);
1881                 if (err)
1882                         goto out;
1883         } else {
1884                 /* Ensure nlk is hashed and visible. */
1885                 smp_rmb();
1886         }
1887 
1888         err = -EMSGSIZE;
1889         if (len > sk->sk_sndbuf - 32)
1890                 goto out;
1891         err = -ENOBUFS;
1892         skb = netlink_alloc_large_skb(len, dst_group);
1893         if (skb == NULL)
1894                 goto out;
1895 
1896         NETLINK_CB(skb).portid  = nlk->portid;
1897         NETLINK_CB(skb).dst_group = dst_group;
1898         NETLINK_CB(skb).creds   = scm.creds;
1899         NETLINK_CB(skb).flags   = netlink_skb_flags;
1900 
1901         err = -EFAULT;
1902         if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
1903                 kfree_skb(skb);
1904                 goto out;
1905         }
1906 
1907         err = security_netlink_send(sk, skb);
1908         if (err) {
1909                 kfree_skb(skb);
1910                 goto out;
1911         }
1912 
1913         if (dst_group) {
1914                 refcount_inc(&skb->users);
1915                 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
1916         }
1917         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
1918 
1919 out:
1920         scm_destroy(&scm);
1921         return err;
1922 }
1923 
1924 static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
1925                            int flags)
1926 {
1927         struct scm_cookie scm;
1928         struct sock *sk = sock->sk;
1929         struct netlink_sock *nlk = nlk_sk(sk);
1930         int noblock = flags&MSG_DONTWAIT;
1931         size_t copied;
1932         struct sk_buff *skb, *data_skb;
1933         int err, ret;
1934 
1935         if (flags&MSG_OOB)
1936                 return -EOPNOTSUPP;
1937 
1938         copied = 0;
1939 
1940         skb = skb_recv_datagram(sk, flags, noblock, &err);
1941         if (skb == NULL)
1942                 goto out;
1943 
1944         data_skb = skb;
1945 
1946 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
1947         if (unlikely(skb_shinfo(skb)->frag_list)) {
1948                 /*
1949                  * If this skb has a frag_list, then here that means that we
1950                  * will have to use the frag_list skb's data for compat tasks
1951                  * and the regular skb's data for normal (non-compat) tasks.
1952                  *
1953                  * If we need to send the compat skb, assign it to the
1954                  * 'data_skb' variable so that it will be used below for data
1955                  * copying. We keep 'skb' for everything else, including
1956                  * freeing both later.
1957                  */
1958                 if (flags & MSG_CMSG_COMPAT)
1959                         data_skb = skb_shinfo(skb)->frag_list;
1960         }
1961 #endif
1962 
1963         /* Record the max length of recvmsg() calls for future allocations */
1964         nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
1965         nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
1966                                      SKB_WITH_OVERHEAD(32768));
1967 
1968         copied = data_skb->len;
1969         if (len < copied) {
1970                 msg->msg_flags |= MSG_TRUNC;
1971                 copied = len;
1972         }
1973 
1974         skb_reset_transport_header(data_skb);
1975         err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
1976 
1977         if (msg->msg_name) {
1978                 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1979                 addr->nl_family = AF_NETLINK;
1980                 addr->nl_pad    = 0;
1981                 addr->nl_pid    = NETLINK_CB(skb).portid;
1982                 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1983                 msg->msg_namelen = sizeof(*addr);
1984         }
1985 
1986         if (nlk->flags & NETLINK_F_RECV_PKTINFO)
1987                 netlink_cmsg_recv_pktinfo(msg, skb);
1988         if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
1989                 netlink_cmsg_listen_all_nsid(sk, msg, skb);
1990 
1991         memset(&scm, 0, sizeof(scm));
1992         scm.creds = *NETLINK_CREDS(skb);
1993         if (flags & MSG_TRUNC)
1994                 copied = data_skb->len;
1995 
1996         skb_free_datagram(sk, skb);
1997 
1998         if (nlk->cb_running &&
1999             atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
2000                 ret = netlink_dump(sk);
2001                 if (ret) {
2002                         sk->sk_err = -ret;
2003                         sk->sk_error_report(sk);
2004                 }
2005         }
2006 
2007         scm_recv(sock, msg, &scm, flags);
2008 out:
2009         netlink_rcv_wake(sk);
2010         return err ? : copied;
2011 }
2012 
2013 static void netlink_data_ready(struct sock *sk)
2014 {
2015         BUG();
2016 }
2017 
2018 /*
2019  *      We export these functions to other modules. They provide a
2020  *      complete set of kernel non-blocking support for message
2021  *      queueing.
2022  */
2023 
2024 struct sock *
2025 __netlink_kernel_create(struct net *net, int unit, struct module *module,
2026                         struct netlink_kernel_cfg *cfg)
2027 {
2028         struct socket *sock;
2029         struct sock *sk;
2030         struct netlink_sock *nlk;
2031         struct listeners *listeners = NULL;
2032         struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
2033         unsigned int groups;
2034 
2035         BUG_ON(!nl_table);
2036 
2037         if (unit < 0 || unit >= MAX_LINKS)
2038                 return NULL;
2039 
2040         if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
2041                 return NULL;
2042 
2043         if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0)
2044                 goto out_sock_release_nosk;
2045 
2046         sk = sock->sk;
2047 
2048         if (!cfg || cfg->groups < 32)
2049                 groups = 32;
2050         else
2051                 groups = cfg->groups;
2052 
2053         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2054         if (!listeners)
2055                 goto out_sock_release;
2056 
2057         sk->sk_data_ready = netlink_data_ready;
2058         if (cfg && cfg->input)
2059                 nlk_sk(sk)->netlink_rcv = cfg->input;
2060 
2061         if (netlink_insert(sk, 0))
2062                 goto out_sock_release;
2063 
2064         nlk = nlk_sk(sk);
2065         nlk->flags |= NETLINK_F_KERNEL_SOCKET;
2066 
2067         netlink_table_grab();
2068         if (!nl_table[unit].registered) {
2069                 nl_table[unit].groups = groups;
2070                 rcu_assign_pointer(nl_table[unit].listeners, listeners);
2071                 nl_table[unit].cb_mutex = cb_mutex;
2072                 nl_table[unit].module = module;
2073                 if (cfg) {
2074                         nl_table[unit].bind = cfg->bind;
2075                         nl_table[unit].unbind = cfg->unbind;
2076                         nl_table[unit].flags = cfg->flags;
2077                         if (cfg->compare)
2078                                 nl_table[unit].compare = cfg->compare;
2079                 }
2080                 nl_table[unit].registered = 1;
2081         } else {
2082                 kfree(listeners);
2083                 nl_table[unit].registered++;
2084         }
2085         netlink_table_ungrab();
2086         return sk;
2087 
2088 out_sock_release:
2089         kfree(listeners);
2090         netlink_kernel_release(sk);
2091         return NULL;
2092 
2093 out_sock_release_nosk:
2094         sock_release(sock);
2095         return NULL;
2096 }
2097 EXPORT_SYMBOL(__netlink_kernel_create);
2098 
2099 void
2100 netlink_kernel_release(struct sock *sk)
2101 {
2102         if (sk == NULL || sk->sk_socket == NULL)
2103                 return;
2104 
2105         sock_release(sk->sk_socket);
2106 }
2107 EXPORT_SYMBOL(netlink_kernel_release);
2108 
2109 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
2110 {
2111         struct listeners *new, *old;
2112         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
2113 
2114         if (groups < 32)
2115                 groups = 32;
2116 
2117         if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
2118                 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
2119                 if (!new)
2120                         return -ENOMEM;
2121                 old = nl_deref_protected(tbl->listeners);
2122                 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
2123                 rcu_assign_pointer(tbl->listeners, new);
2124 
2125                 kfree_rcu(old, rcu);
2126         }
2127         tbl->groups = groups;
2128 
2129         return 0;
2130 }
2131 
2132 /**
2133  * netlink_change_ngroups - change number of multicast groups
2134  *
2135  * This changes the number of multicast groups that are available
2136  * on a certain netlink family. Note that it is not possible to
2137  * change the number of groups to below 32. Also note that it does
2138  * not implicitly call netlink_clear_multicast_users() when the
2139  * number of groups is reduced.
2140  *
2141  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2142  * @groups: The new number of groups.
2143  */
2144 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2145 {
2146         int err;
2147 
2148         netlink_table_grab();
2149         err = __netlink_change_ngroups(sk, groups);
2150         netlink_table_ungrab();
2151 
2152         return err;
2153 }
2154 
2155 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2156 {
2157         struct sock *sk;
2158         struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2159 
2160         sk_for_each_bound(sk, &tbl->mc_list)
2161                 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2162 }
2163 
2164 struct nlmsghdr *
2165 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2166 {
2167         struct nlmsghdr *nlh;
2168         int size = nlmsg_msg_size(len);
2169 
2170         nlh = skb_put(skb, NLMSG_ALIGN(size));
2171         nlh->nlmsg_type = type;
2172         nlh->nlmsg_len = size;
2173         nlh->nlmsg_flags = flags;
2174         nlh->nlmsg_pid = portid;
2175         nlh->nlmsg_seq = seq;
2176         if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2177                 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2178         return nlh;
2179 }
2180 EXPORT_SYMBOL(__nlmsg_put);
2181 
2182 /*
2183  * It looks a bit ugly.
2184  * It would be better to create kernel thread.
2185  */
2186 
2187 static int netlink_dump(struct sock *sk)
2188 {
2189         struct netlink_sock *nlk = nlk_sk(sk);
2190         struct netlink_ext_ack extack = {};
2191         struct netlink_callback *cb;
2192         struct sk_buff *skb = NULL;
2193         struct nlmsghdr *nlh;
2194         struct module *module;
2195         int err = -ENOBUFS;
2196         int alloc_min_size;
2197         int alloc_size;
2198 
2199         mutex_lock(nlk->cb_mutex);
2200         if (!nlk->cb_running) {
2201                 err = -EINVAL;
2202                 goto errout_skb;
2203         }
2204 
2205         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2206                 goto errout_skb;
2207 
2208         /* NLMSG_GOODSIZE is small to avoid high order allocations being
2209          * required, but it makes sense to _attempt_ a 16K bytes allocation
2210          * to reduce number of system calls on dump operations, if user
2211          * ever provided a big enough buffer.
2212          */
2213         cb = &nlk->cb;
2214         alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2215 
2216         if (alloc_min_size < nlk->max_recvmsg_len) {
2217                 alloc_size = nlk->max_recvmsg_len;
2218                 skb = alloc_skb(alloc_size,
2219                                 (GFP_KERNEL & ~__GFP_DIRECT_RECLAIM) |
2220                                 __GFP_NOWARN | __GFP_NORETRY);
2221         }
2222         if (!skb) {
2223                 alloc_size = alloc_min_size;
2224                 skb = alloc_skb(alloc_size, GFP_KERNEL);
2225         }
2226         if (!skb)
2227                 goto errout_skb;
2228 
2229         /* Trim skb to allocated size. User is expected to provide buffer as
2230          * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
2231          * netlink_recvmsg())). dump will pack as many smaller messages as
2232          * could fit within the allocated skb. skb is typically allocated
2233          * with larger space than required (could be as much as near 2x the
2234          * requested size with align to next power of 2 approach). Allowing
2235          * dump to use the excess space makes it difficult for a user to have a
2236          * reasonable static buffer based on the expected largest dump of a
2237          * single netdev. The outcome is MSG_TRUNC error.
2238          */
2239         skb_reserve(skb, skb_tailroom(skb) - alloc_size);
2240         netlink_skb_set_owner_r(skb, sk);
2241 
2242         if (nlk->dump_done_errno > 0) {
2243                 cb->extack = &extack;
2244                 nlk->dump_done_errno = cb->dump(skb, cb);
2245                 cb->extack = NULL;
2246         }
2247 
2248         if (nlk->dump_done_errno > 0 ||
2249             skb_tailroom(skb) < nlmsg_total_size(sizeof(nlk->dump_done_errno))) {
2250                 mutex_unlock(nlk->cb_mutex);
2251 
2252                 if (sk_filter(sk, skb))
2253                         kfree_skb(skb);
2254                 else
2255                         __netlink_sendskb(sk, skb);
2256                 return 0;
2257         }
2258 
2259         nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE,
2260                                sizeof(nlk->dump_done_errno),
2261                                NLM_F_MULTI | cb->answer_flags);
2262         if (WARN_ON(!nlh))
2263                 goto errout_skb;
2264 
2265         nl_dump_check_consistent(cb, nlh);
2266 
2267         memcpy(nlmsg_data(nlh), &nlk->dump_done_errno,
2268                sizeof(nlk->dump_done_errno));
2269 
2270         if (extack._msg && nlk->flags & NETLINK_F_EXT_ACK) {
2271                 nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
2272                 if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack._msg))
2273                         nlmsg_end(skb, nlh);
2274         }
2275 
2276         if (sk_filter(sk, skb))
2277                 kfree_skb(skb);
2278         else
2279                 __netlink_sendskb(sk, skb);
2280 
2281         if (cb->done)
2282                 cb->done(cb);
2283 
2284         nlk->cb_running = false;
2285         module = cb->module;
2286         skb = cb->skb;
2287         mutex_unlock(nlk->cb_mutex);
2288         module_put(module);
2289         consume_skb(skb);
2290         return 0;
2291 
2292 errout_skb:
2293         mutex_unlock(nlk->cb_mutex);
2294         kfree_skb(skb);
2295         return err;
2296 }
2297 
2298 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2299                          const struct nlmsghdr *nlh,
2300                          struct netlink_dump_control *control)
2301 {
2302         struct netlink_sock *nlk, *nlk2;
2303         struct netlink_callback *cb;
2304         struct sock *sk;
2305         int ret;
2306 
2307         refcount_inc(&skb->users);
2308 
2309         sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2310         if (sk == NULL) {
2311                 ret = -ECONNREFUSED;
2312                 goto error_free;
2313         }
2314 
2315         nlk = nlk_sk(sk);
2316         mutex_lock(nlk->cb_mutex);
2317         /* A dump is in progress... */
2318         if (nlk->cb_running) {
2319                 ret = -EBUSY;
2320                 goto error_unlock;
2321         }
2322         /* add reference of module which cb->dump belongs to */
2323         if (!try_module_get(control->module)) {
2324                 ret = -EPROTONOSUPPORT;
2325                 goto error_unlock;
2326         }
2327 
2328         cb = &nlk->cb;
2329         memset(cb, 0, sizeof(*cb));
2330         cb->dump = control->dump;
2331         cb->done = control->done;
2332         cb->nlh = nlh;
2333         cb->data = control->data;
2334         cb->module = control->module;
2335         cb->min_dump_alloc = control->min_dump_alloc;
2336         cb->skb = skb;
2337 
2338         nlk2 = nlk_sk(NETLINK_CB(skb).sk);
2339         cb->strict_check = !!(nlk2->flags & NETLINK_F_STRICT_CHK);
2340 
2341         if (control->start) {
2342                 ret = control->start(cb);
2343                 if (ret)
2344                         goto error_put;
2345         }
2346 
2347         nlk->cb_running = true;
2348         nlk->dump_done_errno = INT_MAX;
2349 
2350         mutex_unlock(nlk->cb_mutex);
2351 
2352         ret = netlink_dump(sk);
2353 
2354         sock_put(sk);
2355 
2356         if (ret)
2357                 return ret;
2358 
2359         /* We successfully started a dump, by returning -EINTR we
2360          * signal not to send ACK even if it was requested.
2361          */
2362         return -EINTR;
2363 
2364 error_put:
2365         module_put(control->module);
2366 error_unlock:
2367         sock_put(sk);
2368         mutex_unlock(nlk->cb_mutex);
2369 error_free:
2370         kfree_skb(skb);
2371         return ret;
2372 }
2373 EXPORT_SYMBOL(__netlink_dump_start);
2374 
2375 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
2376                  const struct netlink_ext_ack *extack)
2377 {
2378         struct sk_buff *skb;
2379         struct nlmsghdr *rep;
2380         struct nlmsgerr *errmsg;
2381         size_t payload = sizeof(*errmsg);
2382         size_t tlvlen = 0;
2383         struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
2384         unsigned int flags = 0;
2385         bool nlk_has_extack = nlk->flags & NETLINK_F_EXT_ACK;
2386 
2387         /* Error messages get the original request appened, unless the user
2388          * requests to cap the error message, and get extra error data if
2389          * requested.
2390          */
2391         if (nlk_has_extack && extack && extack->_msg)
2392                 tlvlen += nla_total_size(strlen(extack->_msg) + 1);
2393 
2394         if (err) {
2395                 if (!(nlk->flags & NETLINK_F_CAP_ACK))
2396                         payload += nlmsg_len(nlh);
2397                 else
2398                         flags |= NLM_F_CAPPED;
2399                 if (nlk_has_extack && extack && extack->bad_attr)
2400                         tlvlen += nla_total_size(sizeof(u32));
2401         } else {
2402                 flags |= NLM_F_CAPPED;
2403 
2404                 if (nlk_has_extack && extack && extack->cookie_len)
2405                         tlvlen += nla_total_size(extack->cookie_len);
2406         }
2407 
2408         if (tlvlen)
2409                 flags |= NLM_F_ACK_TLVS;
2410 
2411         skb = nlmsg_new(payload + tlvlen, GFP_KERNEL);
2412         if (!skb) {
2413                 NETLINK_CB(in_skb).sk->sk_err = ENOBUFS;
2414                 NETLINK_CB(in_skb).sk->sk_error_report(NETLINK_CB(in_skb).sk);
2415                 return;
2416         }
2417 
2418         rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2419                           NLMSG_ERROR, payload, flags);
2420         errmsg = nlmsg_data(rep);
2421         errmsg->error = err;
2422         memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
2423 
2424         if (nlk_has_extack && extack) {
2425                 if (extack->_msg) {
2426                         WARN_ON(nla_put_string(skb, NLMSGERR_ATTR_MSG,
2427                                                extack->_msg));
2428                 }
2429                 if (err) {
2430                         if (extack->bad_attr &&
2431                             !WARN_ON((u8 *)extack->bad_attr < in_skb->data ||
2432                                      (u8 *)extack->bad_attr >= in_skb->data +
2433                                                                in_skb->len))
2434                                 WARN_ON(nla_put_u32(skb, NLMSGERR_ATTR_OFFS,
2435                                                     (u8 *)extack->bad_attr -
2436                                                     in_skb->data));
2437                 } else {
2438                         if (extack->cookie_len)
2439                                 WARN_ON(nla_put(skb, NLMSGERR_ATTR_COOKIE,
2440                                                 extack->cookie_len,
2441                                                 extack->cookie));
2442                 }
2443         }
2444 
2445         nlmsg_end(skb, rep);
2446 
2447         netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
2448 }
2449 EXPORT_SYMBOL(netlink_ack);
2450 
2451 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2452                                                    struct nlmsghdr *,
2453                                                    struct netlink_ext_ack *))
2454 {
2455         struct netlink_ext_ack extack;
2456         struct nlmsghdr *nlh;
2457         int err;
2458 
2459         while (skb->len >= nlmsg_total_size(0)) {
2460                 int msglen;
2461 
2462                 memset(&extack, 0, sizeof(extack));
2463                 nlh = nlmsg_hdr(skb);
2464                 err = 0;
2465 
2466                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2467                         return 0;
2468 
2469                 /* Only requests are handled by the kernel */
2470                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2471                         goto ack;
2472 
2473                 /* Skip control messages */
2474                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2475                         goto ack;
2476 
2477                 err = cb(skb, nlh, &extack);
2478                 if (err == -EINTR)
2479                         goto skip;
2480 
2481 ack:
2482                 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2483                         netlink_ack(skb, nlh, err, &extack);
2484 
2485 skip:
2486                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2487                 if (msglen > skb->len)
2488                         msglen = skb->len;
2489                 skb_pull(skb, msglen);
2490         }
2491 
2492         return 0;
2493 }
2494 EXPORT_SYMBOL(netlink_rcv_skb);
2495 
2496 /**
2497  * nlmsg_notify - send a notification netlink message
2498  * @sk: netlink socket to use
2499  * @skb: notification message
2500  * @portid: destination netlink portid for reports or 0
2501  * @group: destination multicast group or 0
2502  * @report: 1 to report back, 0 to disable
2503  * @flags: allocation flags
2504  */
2505 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2506                  unsigned int group, int report, gfp_t flags)
2507 {
2508         int err = 0;
2509 
2510         if (group) {
2511                 int exclude_portid = 0;
2512 
2513                 if (report) {
2514                         refcount_inc(&skb->users);
2515                         exclude_portid = portid;
2516                 }
2517 
2518                 /* errors reported via destination sk->sk_err, but propagate
2519                  * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2520                 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2521         }
2522 
2523         if (report) {
2524                 int err2;
2525 
2526                 err2 = nlmsg_unicast(sk, skb, portid);
2527                 if (!err || err == -ESRCH)
2528                         err = err2;
2529         }
2530 
2531         return err;
2532 }
2533 EXPORT_SYMBOL(nlmsg_notify);
2534 
2535 #ifdef CONFIG_PROC_FS
2536 struct nl_seq_iter {
2537         struct seq_net_private p;
2538         struct rhashtable_iter hti;
2539         int link;
2540 };
2541 
2542 static void netlink_walk_start(struct nl_seq_iter *iter)
2543 {
2544         rhashtable_walk_enter(&nl_table[iter->link].hash, &iter->hti);
2545         rhashtable_walk_start(&iter->hti);
2546 }
2547 
2548 static void netlink_walk_stop(struct nl_seq_iter *iter)
2549 {
2550         rhashtable_walk_stop(&iter->hti);
2551         rhashtable_walk_exit(&iter->hti);
2552 }
2553 
2554 static void *__netlink_seq_next(struct seq_file *seq)
2555 {
2556         struct nl_seq_iter *iter = seq->private;
2557         struct netlink_sock *nlk;
2558 
2559         do {
2560                 for (;;) {
2561                         nlk = rhashtable_walk_next(&iter->hti);
2562 
2563                         if (IS_ERR(nlk)) {
2564                                 if (PTR_ERR(nlk) == -EAGAIN)
2565                                         continue;
2566 
2567                                 return nlk;
2568                         }
2569 
2570                         if (nlk)
2571                                 break;
2572 
2573                         netlink_walk_stop(iter);
2574                         if (++iter->link >= MAX_LINKS)
2575                                 return NULL;
2576 
2577                         netlink_walk_start(iter);
2578                 }
2579         } while (sock_net(&nlk->sk) != seq_file_net(seq));
2580 
2581         return nlk;
2582 }
2583 
2584 static void *netlink_seq_start(struct seq_file *seq, loff_t *posp)
2585 {
2586         struct nl_seq_iter *iter = seq->private;
2587         void *obj = SEQ_START_TOKEN;
2588         loff_t pos;
2589 
2590         iter->link = 0;
2591 
2592         netlink_walk_start(iter);
2593 
2594         for (pos = *posp; pos && obj && !IS_ERR(obj); pos--)
2595                 obj = __netlink_seq_next(seq);
2596 
2597         return obj;
2598 }
2599 
2600 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2601 {
2602         ++*pos;
2603         return __netlink_seq_next(seq);
2604 }
2605 
2606 static void netlink_seq_stop(struct seq_file *seq, void *v)
2607 {
2608         struct nl_seq_iter *iter = seq->private;
2609 
2610         if (iter->link >= MAX_LINKS)
2611                 return;
2612 
2613         netlink_walk_stop(iter);
2614 }
2615 
2616 
2617 static int netlink_seq_show(struct seq_file *seq, void *v)
2618 {
2619         if (v == SEQ_START_TOKEN) {
2620                 seq_puts(seq,
2621                          "sk               Eth Pid        Groups   "
2622                          "Rmem     Wmem     Dump  Locks    Drops    Inode\n");
2623         } else {
2624                 struct sock *s = v;
2625                 struct netlink_sock *nlk = nlk_sk(s);
2626 
2627                 seq_printf(seq, "%pK %-3d %-10u %08x %-8d %-8d %-5d %-8d %-8u %-8lu\n",
2628                            s,
2629                            s->sk_protocol,
2630                            nlk->portid,
2631                            nlk->groups ? (u32)nlk->groups[0] : 0,
2632                            sk_rmem_alloc_get(s),
2633                            sk_wmem_alloc_get(s),
2634                            nlk->cb_running,
2635                            refcount_read(&s->sk_refcnt),
2636                            atomic_read(&s->sk_drops),
2637                            sock_i_ino(s)
2638                         );
2639 
2640         }
2641         return 0;
2642 }
2643 
2644 static const struct seq_operations netlink_seq_ops = {
2645         .start  = netlink_seq_start,
2646         .next   = netlink_seq_next,
2647         .stop   = netlink_seq_stop,
2648         .show   = netlink_seq_show,
2649 };
2650 #endif
2651 
2652 int netlink_register_notifier(struct notifier_block *nb)
2653 {
2654         return blocking_notifier_chain_register(&netlink_chain, nb);
2655 }
2656 EXPORT_SYMBOL(netlink_register_notifier);
2657 
2658 int netlink_unregister_notifier(struct notifier_block *nb)
2659 {
2660         return blocking_notifier_chain_unregister(&netlink_chain, nb);
2661 }
2662 EXPORT_SYMBOL(netlink_unregister_notifier);
2663 
2664 static const struct proto_ops netlink_ops = {
2665         .family =       PF_NETLINK,
2666         .owner =        THIS_MODULE,
2667         .release =      netlink_release,
2668         .bind =         netlink_bind,
2669         .connect =      netlink_connect,
2670         .socketpair =   sock_no_socketpair,
2671         .accept =       sock_no_accept,
2672         .getname =      netlink_getname,
2673         .poll =         datagram_poll,
2674         .ioctl =        netlink_ioctl,
2675         .listen =       sock_no_listen,
2676         .shutdown =     sock_no_shutdown,
2677         .setsockopt =   netlink_setsockopt,
2678         .getsockopt =   netlink_getsockopt,
2679         .sendmsg =      netlink_sendmsg,
2680         .recvmsg =      netlink_recvmsg,
2681         .mmap =         sock_no_mmap,
2682         .sendpage =     sock_no_sendpage,
2683 };
2684 
2685 static const struct net_proto_family netlink_family_ops = {
2686         .family = PF_NETLINK,
2687         .create = netlink_create,
2688         .owner  = THIS_MODULE,  /* for consistency 8) */
2689 };
2690 
2691 static int __net_init netlink_net_init(struct net *net)
2692 {
2693 #ifdef CONFIG_PROC_FS
2694         if (!proc_create_net("netlink", 0, net->proc_net, &netlink_seq_ops,
2695                         sizeof(struct nl_seq_iter)))
2696                 return -ENOMEM;
2697 #endif
2698         return 0;
2699 }
2700 
2701 static void __net_exit netlink_net_exit(struct net *net)
2702 {
2703 #ifdef CONFIG_PROC_FS
2704         remove_proc_entry("netlink", net->proc_net);
2705 #endif
2706 }
2707 
2708 static void __init netlink_add_usersock_entry(void)
2709 {
2710         struct listeners *listeners;
2711         int groups = 32;
2712 
2713         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2714         if (!listeners)
2715                 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2716 
2717         netlink_table_grab();
2718 
2719         nl_table[NETLINK_USERSOCK].groups = groups;
2720         rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2721         nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2722         nl_table[NETLINK_USERSOCK].registered = 1;
2723         nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
2724 
2725         netlink_table_ungrab();
2726 }
2727 
2728 static struct pernet_operations __net_initdata netlink_net_ops = {
2729         .init = netlink_net_init,
2730         .exit = netlink_net_exit,
2731 };
2732 
2733 static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
2734 {
2735         const struct netlink_sock *nlk = data;
2736         struct netlink_compare_arg arg;
2737 
2738         netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
2739         return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
2740 }
2741 
2742 static const struct rhashtable_params netlink_rhashtable_params = {
2743         .head_offset = offsetof(struct netlink_sock, node),
2744         .key_len = netlink_compare_arg_len,
2745         .obj_hashfn = netlink_hash,
2746         .obj_cmpfn = netlink_compare,
2747         .automatic_shrinking = true,
2748 };
2749 
2750 static int __init netlink_proto_init(void)
2751 {
2752         int i;
2753         int err = proto_register(&netlink_proto, 0);
2754 
2755         if (err != 0)
2756                 goto out;
2757 
2758         BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2759 
2760         nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2761         if (!nl_table)
2762                 goto panic;
2763 
2764         for (i = 0; i < MAX_LINKS; i++) {
2765                 if (rhashtable_init(&nl_table[i].hash,
2766                                     &netlink_rhashtable_params) < 0) {
2767                         while (--i > 0)
2768                                 rhashtable_destroy(&nl_table[i].hash);
2769                         kfree(nl_table);
2770                         goto panic;
2771                 }
2772         }
2773 
2774         netlink_add_usersock_entry();
2775 
2776         sock_register(&netlink_family_ops);
2777         register_pernet_subsys(&netlink_net_ops);
2778         register_pernet_subsys(&netlink_tap_net_ops);
2779         /* The netlink device handler may be needed early. */
2780         rtnetlink_init();
2781 out:
2782         return err;
2783 panic:
2784         panic("netlink_init: Cannot allocate nl_table\n");
2785 }
2786 
2787 core_initcall(netlink_proto_init);
2788 

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