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Linux/net/netlink/af_netlink.c

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

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