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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 <asm/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 
 66 #include <net/net_namespace.h>
 67 #include <net/sock.h>
 68 #include <net/scm.h>
 69 #include <net/netlink.h>
 70 
 71 #include "af_netlink.h"
 72 
 73 struct listeners {
 74         struct rcu_head         rcu;
 75         unsigned long           masks[0];
 76 };
 77 
 78 /* state bits */
 79 #define NETLINK_S_CONGESTED             0x0
 80 
 81 /* flags */
 82 #define NETLINK_F_KERNEL_SOCKET         0x1
 83 #define NETLINK_F_RECV_PKTINFO          0x2
 84 #define NETLINK_F_BROADCAST_SEND_ERROR  0x4
 85 #define NETLINK_F_RECV_NO_ENOBUFS       0x8
 86 #define NETLINK_F_LISTEN_ALL_NSID       0x10
 87 #define NETLINK_F_CAP_ACK               0x20
 88 
 89 static inline int netlink_is_kernel(struct sock *sk)
 90 {
 91         return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
 92 }
 93 
 94 struct netlink_table *nl_table __read_mostly;
 95 EXPORT_SYMBOL_GPL(nl_table);
 96 
 97 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
 98 
 99 static int netlink_dump(struct sock *sk);
100 static void netlink_skb_destructor(struct sk_buff *skb);
101 
102 /* nl_table locking explained:
103  * Lookup and traversal are protected with an RCU read-side lock. Insertion
104  * and removal are protected with per bucket lock while using RCU list
105  * modification primitives and may run in parallel to RCU protected lookups.
106  * Destruction of the Netlink socket may only occur *after* nl_table_lock has
107  * been acquired * either during or after the socket has been removed from
108  * the list and after an RCU grace period.
109  */
110 DEFINE_RWLOCK(nl_table_lock);
111 EXPORT_SYMBOL_GPL(nl_table_lock);
112 static atomic_t nl_table_users = ATOMIC_INIT(0);
113 
114 #define nl_deref_protected(X) rcu_dereference_protected(X, lockdep_is_held(&nl_table_lock));
115 
116 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
117 
118 static DEFINE_SPINLOCK(netlink_tap_lock);
119 static struct list_head netlink_tap_all __read_mostly;
120 
121 static const struct rhashtable_params netlink_rhashtable_params;
122 
123 static inline u32 netlink_group_mask(u32 group)
124 {
125         return group ? 1 << (group - 1) : 0;
126 }
127 
128 static struct sk_buff *netlink_to_full_skb(const struct sk_buff *skb,
129                                            gfp_t gfp_mask)
130 {
131         unsigned int len = skb_end_offset(skb);
132         struct sk_buff *new;
133 
134         new = alloc_skb(len, gfp_mask);
135         if (new == NULL)
136                 return NULL;
137 
138         NETLINK_CB(new).portid = NETLINK_CB(skb).portid;
139         NETLINK_CB(new).dst_group = NETLINK_CB(skb).dst_group;
140         NETLINK_CB(new).creds = NETLINK_CB(skb).creds;
141 
142         memcpy(skb_put(new, len), skb->data, len);
143         return new;
144 }
145 
146 int netlink_add_tap(struct netlink_tap *nt)
147 {
148         if (unlikely(nt->dev->type != ARPHRD_NETLINK))
149                 return -EINVAL;
150 
151         spin_lock(&netlink_tap_lock);
152         list_add_rcu(&nt->list, &netlink_tap_all);
153         spin_unlock(&netlink_tap_lock);
154 
155         __module_get(nt->module);
156 
157         return 0;
158 }
159 EXPORT_SYMBOL_GPL(netlink_add_tap);
160 
161 static int __netlink_remove_tap(struct netlink_tap *nt)
162 {
163         bool found = false;
164         struct netlink_tap *tmp;
165 
166         spin_lock(&netlink_tap_lock);
167 
168         list_for_each_entry(tmp, &netlink_tap_all, list) {
169                 if (nt == tmp) {
170                         list_del_rcu(&nt->list);
171                         found = true;
172                         goto out;
173                 }
174         }
175 
176         pr_warn("__netlink_remove_tap: %p not found\n", nt);
177 out:
178         spin_unlock(&netlink_tap_lock);
179 
180         if (found)
181                 module_put(nt->module);
182 
183         return found ? 0 : -ENODEV;
184 }
185 
186 int netlink_remove_tap(struct netlink_tap *nt)
187 {
188         int ret;
189 
190         ret = __netlink_remove_tap(nt);
191         synchronize_net();
192 
193         return ret;
194 }
195 EXPORT_SYMBOL_GPL(netlink_remove_tap);
196 
197 static bool netlink_filter_tap(const struct sk_buff *skb)
198 {
199         struct sock *sk = skb->sk;
200 
201         /* We take the more conservative approach and
202          * whitelist socket protocols that may pass.
203          */
204         switch (sk->sk_protocol) {
205         case NETLINK_ROUTE:
206         case NETLINK_USERSOCK:
207         case NETLINK_SOCK_DIAG:
208         case NETLINK_NFLOG:
209         case NETLINK_XFRM:
210         case NETLINK_FIB_LOOKUP:
211         case NETLINK_NETFILTER:
212         case NETLINK_GENERIC:
213                 return true;
214         }
215 
216         return false;
217 }
218 
219 static int __netlink_deliver_tap_skb(struct sk_buff *skb,
220                                      struct net_device *dev)
221 {
222         struct sk_buff *nskb;
223         struct sock *sk = skb->sk;
224         int ret = -ENOMEM;
225 
226         dev_hold(dev);
227 
228         if (is_vmalloc_addr(skb->head))
229                 nskb = netlink_to_full_skb(skb, GFP_ATOMIC);
230         else
231                 nskb = skb_clone(skb, GFP_ATOMIC);
232         if (nskb) {
233                 nskb->dev = dev;
234                 nskb->protocol = htons((u16) sk->sk_protocol);
235                 nskb->pkt_type = netlink_is_kernel(sk) ?
236                                  PACKET_KERNEL : PACKET_USER;
237                 skb_reset_network_header(nskb);
238                 ret = dev_queue_xmit(nskb);
239                 if (unlikely(ret > 0))
240                         ret = net_xmit_errno(ret);
241         }
242 
243         dev_put(dev);
244         return ret;
245 }
246 
247 static void __netlink_deliver_tap(struct sk_buff *skb)
248 {
249         int ret;
250         struct netlink_tap *tmp;
251 
252         if (!netlink_filter_tap(skb))
253                 return;
254 
255         list_for_each_entry_rcu(tmp, &netlink_tap_all, list) {
256                 ret = __netlink_deliver_tap_skb(skb, tmp->dev);
257                 if (unlikely(ret))
258                         break;
259         }
260 }
261 
262 static void netlink_deliver_tap(struct sk_buff *skb)
263 {
264         rcu_read_lock();
265 
266         if (unlikely(!list_empty(&netlink_tap_all)))
267                 __netlink_deliver_tap(skb);
268 
269         rcu_read_unlock();
270 }
271 
272 static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,
273                                        struct sk_buff *skb)
274 {
275         if (!(netlink_is_kernel(dst) && netlink_is_kernel(src)))
276                 netlink_deliver_tap(skb);
277 }
278 
279 static void netlink_overrun(struct sock *sk)
280 {
281         struct netlink_sock *nlk = nlk_sk(sk);
282 
283         if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
284                 if (!test_and_set_bit(NETLINK_S_CONGESTED,
285                                       &nlk_sk(sk)->state)) {
286                         sk->sk_err = ENOBUFS;
287                         sk->sk_error_report(sk);
288                 }
289         }
290         atomic_inc(&sk->sk_drops);
291 }
292 
293 static void netlink_rcv_wake(struct sock *sk)
294 {
295         struct netlink_sock *nlk = nlk_sk(sk);
296 
297         if (skb_queue_empty(&sk->sk_receive_queue))
298                 clear_bit(NETLINK_S_CONGESTED, &nlk->state);
299         if (!test_bit(NETLINK_S_CONGESTED, &nlk->state))
300                 wake_up_interruptible(&nlk->wait);
301 }
302 
303 static void netlink_skb_destructor(struct sk_buff *skb)
304 {
305         if (is_vmalloc_addr(skb->head)) {
306                 if (!skb->cloned ||
307                     !atomic_dec_return(&(skb_shinfo(skb)->dataref)))
308                         vfree(skb->head);
309 
310                 skb->head = NULL;
311         }
312         if (skb->sk != NULL)
313                 sock_rfree(skb);
314 }
315 
316 static void netlink_skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
317 {
318         WARN_ON(skb->sk != NULL);
319         skb->sk = sk;
320         skb->destructor = netlink_skb_destructor;
321         atomic_add(skb->truesize, &sk->sk_rmem_alloc);
322         sk_mem_charge(sk, skb->truesize);
323 }
324 
325 static void netlink_sock_destruct(struct sock *sk)
326 {
327         struct netlink_sock *nlk = nlk_sk(sk);
328 
329         if (nlk->cb_running) {
330                 if (nlk->cb.done)
331                         nlk->cb.done(&nlk->cb);
332 
333                 module_put(nlk->cb.module);
334                 kfree_skb(nlk->cb.skb);
335         }
336 
337         skb_queue_purge(&sk->sk_receive_queue);
338 
339         if (!sock_flag(sk, SOCK_DEAD)) {
340                 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
341                 return;
342         }
343 
344         WARN_ON(atomic_read(&sk->sk_rmem_alloc));
345         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
346         WARN_ON(nlk_sk(sk)->groups);
347 }
348 
349 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
350  * SMP. Look, when several writers sleep and reader wakes them up, all but one
351  * immediately hit write lock and grab all the cpus. Exclusive sleep solves
352  * this, _but_ remember, it adds useless work on UP machines.
353  */
354 
355 void netlink_table_grab(void)
356         __acquires(nl_table_lock)
357 {
358         might_sleep();
359 
360         write_lock_irq(&nl_table_lock);
361 
362         if (atomic_read(&nl_table_users)) {
363                 DECLARE_WAITQUEUE(wait, current);
364 
365                 add_wait_queue_exclusive(&nl_table_wait, &wait);
366                 for (;;) {
367                         set_current_state(TASK_UNINTERRUPTIBLE);
368                         if (atomic_read(&nl_table_users) == 0)
369                                 break;
370                         write_unlock_irq(&nl_table_lock);
371                         schedule();
372                         write_lock_irq(&nl_table_lock);
373                 }
374 
375                 __set_current_state(TASK_RUNNING);
376                 remove_wait_queue(&nl_table_wait, &wait);
377         }
378 }
379 
380 void netlink_table_ungrab(void)
381         __releases(nl_table_lock)
382 {
383         write_unlock_irq(&nl_table_lock);
384         wake_up(&nl_table_wait);
385 }
386 
387 static inline void
388 netlink_lock_table(void)
389 {
390         /* read_lock() synchronizes us to netlink_table_grab */
391 
392         read_lock(&nl_table_lock);
393         atomic_inc(&nl_table_users);
394         read_unlock(&nl_table_lock);
395 }
396 
397 static inline void
398 netlink_unlock_table(void)
399 {
400         if (atomic_dec_and_test(&nl_table_users))
401                 wake_up(&nl_table_wait);
402 }
403 
404 struct netlink_compare_arg
405 {
406         possible_net_t pnet;
407         u32 portid;
408 };
409 
410 /* Doing sizeof directly may yield 4 extra bytes on 64-bit. */
411 #define netlink_compare_arg_len \
412         (offsetof(struct netlink_compare_arg, portid) + sizeof(u32))
413 
414 static inline int netlink_compare(struct rhashtable_compare_arg *arg,
415                                   const void *ptr)
416 {
417         const struct netlink_compare_arg *x = arg->key;
418         const struct netlink_sock *nlk = ptr;
419 
420         return nlk->portid != x->portid ||
421                !net_eq(sock_net(&nlk->sk), read_pnet(&x->pnet));
422 }
423 
424 static void netlink_compare_arg_init(struct netlink_compare_arg *arg,
425                                      struct net *net, u32 portid)
426 {
427         memset(arg, 0, sizeof(*arg));
428         write_pnet(&arg->pnet, net);
429         arg->portid = portid;
430 }
431 
432 static struct sock *__netlink_lookup(struct netlink_table *table, u32 portid,
433                                      struct net *net)
434 {
435         struct netlink_compare_arg arg;
436 
437         netlink_compare_arg_init(&arg, net, portid);
438         return rhashtable_lookup_fast(&table->hash, &arg,
439                                       netlink_rhashtable_params);
440 }
441 
442 static int __netlink_insert(struct netlink_table *table, struct sock *sk)
443 {
444         struct netlink_compare_arg arg;
445 
446         netlink_compare_arg_init(&arg, sock_net(sk), nlk_sk(sk)->portid);
447         return rhashtable_lookup_insert_key(&table->hash, &arg,
448                                             &nlk_sk(sk)->node,
449                                             netlink_rhashtable_params);
450 }
451 
452 static struct sock *netlink_lookup(struct net *net, int protocol, u32 portid)
453 {
454         struct netlink_table *table = &nl_table[protocol];
455         struct sock *sk;
456 
457         rcu_read_lock();
458         sk = __netlink_lookup(table, portid, net);
459         if (sk)
460                 sock_hold(sk);
461         rcu_read_unlock();
462 
463         return sk;
464 }
465 
466 static const struct proto_ops netlink_ops;
467 
468 static void
469 netlink_update_listeners(struct sock *sk)
470 {
471         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
472         unsigned long mask;
473         unsigned int i;
474         struct listeners *listeners;
475 
476         listeners = nl_deref_protected(tbl->listeners);
477         if (!listeners)
478                 return;
479 
480         for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
481                 mask = 0;
482                 sk_for_each_bound(sk, &tbl->mc_list) {
483                         if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
484                                 mask |= nlk_sk(sk)->groups[i];
485                 }
486                 listeners->masks[i] = mask;
487         }
488         /* this function is only called with the netlink table "grabbed", which
489          * makes sure updates are visible before bind or setsockopt return. */
490 }
491 
492 static int netlink_insert(struct sock *sk, u32 portid)
493 {
494         struct netlink_table *table = &nl_table[sk->sk_protocol];
495         int err;
496 
497         lock_sock(sk);
498 
499         err = nlk_sk(sk)->portid == portid ? 0 : -EBUSY;
500         if (nlk_sk(sk)->bound)
501                 goto err;
502 
503         err = -ENOMEM;
504         if (BITS_PER_LONG > 32 &&
505             unlikely(atomic_read(&table->hash.nelems) >= UINT_MAX))
506                 goto err;
507 
508         nlk_sk(sk)->portid = portid;
509         sock_hold(sk);
510 
511         err = __netlink_insert(table, sk);
512         if (err) {
513                 /* In case the hashtable backend returns with -EBUSY
514                  * from here, it must not escape to the caller.
515                  */
516                 if (unlikely(err == -EBUSY))
517                         err = -EOVERFLOW;
518                 if (err == -EEXIST)
519                         err = -EADDRINUSE;
520                 sock_put(sk);
521                 goto err;
522         }
523 
524         /* We need to ensure that the socket is hashed and visible. */
525         smp_wmb();
526         nlk_sk(sk)->bound = portid;
527 
528 err:
529         release_sock(sk);
530         return err;
531 }
532 
533 static void netlink_remove(struct sock *sk)
534 {
535         struct netlink_table *table;
536 
537         table = &nl_table[sk->sk_protocol];
538         if (!rhashtable_remove_fast(&table->hash, &nlk_sk(sk)->node,
539                                     netlink_rhashtable_params)) {
540                 WARN_ON(atomic_read(&sk->sk_refcnt) == 1);
541                 __sock_put(sk);
542         }
543 
544         netlink_table_grab();
545         if (nlk_sk(sk)->subscriptions) {
546                 __sk_del_bind_node(sk);
547                 netlink_update_listeners(sk);
548         }
549         if (sk->sk_protocol == NETLINK_GENERIC)
550                 atomic_inc(&genl_sk_destructing_cnt);
551         netlink_table_ungrab();
552 }
553 
554 static struct proto netlink_proto = {
555         .name     = "NETLINK",
556         .owner    = THIS_MODULE,
557         .obj_size = sizeof(struct netlink_sock),
558 };
559 
560 static int __netlink_create(struct net *net, struct socket *sock,
561                             struct mutex *cb_mutex, int protocol,
562                             int kern)
563 {
564         struct sock *sk;
565         struct netlink_sock *nlk;
566 
567         sock->ops = &netlink_ops;
568 
569         sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto, kern);
570         if (!sk)
571                 return -ENOMEM;
572 
573         sock_init_data(sock, sk);
574 
575         nlk = nlk_sk(sk);
576         if (cb_mutex) {
577                 nlk->cb_mutex = cb_mutex;
578         } else {
579                 nlk->cb_mutex = &nlk->cb_def_mutex;
580                 mutex_init(nlk->cb_mutex);
581         }
582         init_waitqueue_head(&nlk->wait);
583 
584         sk->sk_destruct = netlink_sock_destruct;
585         sk->sk_protocol = protocol;
586         return 0;
587 }
588 
589 static int netlink_create(struct net *net, struct socket *sock, int protocol,
590                           int kern)
591 {
592         struct module *module = NULL;
593         struct mutex *cb_mutex;
594         struct netlink_sock *nlk;
595         int (*bind)(struct net *net, int group);
596         void (*unbind)(struct net *net, int group);
597         int err = 0;
598 
599         sock->state = SS_UNCONNECTED;
600 
601         if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
602                 return -ESOCKTNOSUPPORT;
603 
604         if (protocol < 0 || protocol >= MAX_LINKS)
605                 return -EPROTONOSUPPORT;
606 
607         netlink_lock_table();
608 #ifdef CONFIG_MODULES
609         if (!nl_table[protocol].registered) {
610                 netlink_unlock_table();
611                 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
612                 netlink_lock_table();
613         }
614 #endif
615         if (nl_table[protocol].registered &&
616             try_module_get(nl_table[protocol].module))
617                 module = nl_table[protocol].module;
618         else
619                 err = -EPROTONOSUPPORT;
620         cb_mutex = nl_table[protocol].cb_mutex;
621         bind = nl_table[protocol].bind;
622         unbind = nl_table[protocol].unbind;
623         netlink_unlock_table();
624 
625         if (err < 0)
626                 goto out;
627 
628         err = __netlink_create(net, sock, cb_mutex, protocol, kern);
629         if (err < 0)
630                 goto out_module;
631 
632         local_bh_disable();
633         sock_prot_inuse_add(net, &netlink_proto, 1);
634         local_bh_enable();
635 
636         nlk = nlk_sk(sock->sk);
637         nlk->module = module;
638         nlk->netlink_bind = bind;
639         nlk->netlink_unbind = unbind;
640 out:
641         return err;
642 
643 out_module:
644         module_put(module);
645         goto out;
646 }
647 
648 static void deferred_put_nlk_sk(struct rcu_head *head)
649 {
650         struct netlink_sock *nlk = container_of(head, struct netlink_sock, rcu);
651 
652         sock_put(&nlk->sk);
653 }
654 
655 static int netlink_release(struct socket *sock)
656 {
657         struct sock *sk = sock->sk;
658         struct netlink_sock *nlk;
659 
660         if (!sk)
661                 return 0;
662 
663         netlink_remove(sk);
664         sock_orphan(sk);
665         nlk = nlk_sk(sk);
666 
667         /*
668          * OK. Socket is unlinked, any packets that arrive now
669          * will be purged.
670          */
671 
672         /* must not acquire netlink_table_lock in any way again before unbind
673          * and notifying genetlink is done as otherwise it might deadlock
674          */
675         if (nlk->netlink_unbind) {
676                 int i;
677 
678                 for (i = 0; i < nlk->ngroups; i++)
679                         if (test_bit(i, nlk->groups))
680                                 nlk->netlink_unbind(sock_net(sk), i + 1);
681         }
682         if (sk->sk_protocol == NETLINK_GENERIC &&
683             atomic_dec_return(&genl_sk_destructing_cnt) == 0)
684                 wake_up(&genl_sk_destructing_waitq);
685 
686         sock->sk = NULL;
687         wake_up_interruptible_all(&nlk->wait);
688 
689         skb_queue_purge(&sk->sk_write_queue);
690 
691         if (nlk->portid && nlk->bound) {
692                 struct netlink_notify n = {
693                                                 .net = sock_net(sk),
694                                                 .protocol = sk->sk_protocol,
695                                                 .portid = nlk->portid,
696                                           };
697                 atomic_notifier_call_chain(&netlink_chain,
698                                 NETLINK_URELEASE, &n);
699         }
700 
701         module_put(nlk->module);
702 
703         if (netlink_is_kernel(sk)) {
704                 netlink_table_grab();
705                 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
706                 if (--nl_table[sk->sk_protocol].registered == 0) {
707                         struct listeners *old;
708 
709                         old = nl_deref_protected(nl_table[sk->sk_protocol].listeners);
710                         RCU_INIT_POINTER(nl_table[sk->sk_protocol].listeners, NULL);
711                         kfree_rcu(old, rcu);
712                         nl_table[sk->sk_protocol].module = NULL;
713                         nl_table[sk->sk_protocol].bind = NULL;
714                         nl_table[sk->sk_protocol].unbind = NULL;
715                         nl_table[sk->sk_protocol].flags = 0;
716                         nl_table[sk->sk_protocol].registered = 0;
717                 }
718                 netlink_table_ungrab();
719         }
720 
721         kfree(nlk->groups);
722         nlk->groups = NULL;
723 
724         local_bh_disable();
725         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
726         local_bh_enable();
727         call_rcu(&nlk->rcu, deferred_put_nlk_sk);
728         return 0;
729 }
730 
731 static int netlink_autobind(struct socket *sock)
732 {
733         struct sock *sk = sock->sk;
734         struct net *net = sock_net(sk);
735         struct netlink_table *table = &nl_table[sk->sk_protocol];
736         s32 portid = task_tgid_vnr(current);
737         int err;
738         s32 rover = -4096;
739         bool ok;
740 
741 retry:
742         cond_resched();
743         rcu_read_lock();
744         ok = !__netlink_lookup(table, portid, net);
745         rcu_read_unlock();
746         if (!ok) {
747                 /* Bind collision, search negative portid values. */
748                 if (rover == -4096)
749                         /* rover will be in range [S32_MIN, -4097] */
750                         rover = S32_MIN + prandom_u32_max(-4096 - S32_MIN);
751                 else if (rover >= -4096)
752                         rover = -4097;
753                 portid = rover--;
754                 goto retry;
755         }
756 
757         err = netlink_insert(sk, portid);
758         if (err == -EADDRINUSE)
759                 goto retry;
760 
761         /* If 2 threads race to autobind, that is fine.  */
762         if (err == -EBUSY)
763                 err = 0;
764 
765         return err;
766 }
767 
768 /**
769  * __netlink_ns_capable - General netlink message capability test
770  * @nsp: NETLINK_CB of the socket buffer holding a netlink command from userspace.
771  * @user_ns: The user namespace of the capability to use
772  * @cap: The capability to use
773  *
774  * Test to see if the opener of the socket we received the message
775  * from had when the netlink socket was created and the sender of the
776  * message has has the capability @cap in the user namespace @user_ns.
777  */
778 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
779                         struct user_namespace *user_ns, int cap)
780 {
781         return ((nsp->flags & NETLINK_SKB_DST) ||
782                 file_ns_capable(nsp->sk->sk_socket->file, user_ns, cap)) &&
783                 ns_capable(user_ns, cap);
784 }
785 EXPORT_SYMBOL(__netlink_ns_capable);
786 
787 /**
788  * netlink_ns_capable - General netlink message capability test
789  * @skb: socket buffer holding a netlink command from userspace
790  * @user_ns: The user namespace of the capability to use
791  * @cap: The capability to use
792  *
793  * Test to see if the opener of the socket we received the message
794  * from had when the netlink socket was created and the sender of the
795  * message has has the capability @cap in the user namespace @user_ns.
796  */
797 bool netlink_ns_capable(const struct sk_buff *skb,
798                         struct user_namespace *user_ns, int cap)
799 {
800         return __netlink_ns_capable(&NETLINK_CB(skb), user_ns, cap);
801 }
802 EXPORT_SYMBOL(netlink_ns_capable);
803 
804 /**
805  * netlink_capable - Netlink global message capability test
806  * @skb: socket buffer holding a netlink command from userspace
807  * @cap: The capability to use
808  *
809  * Test to see if the opener of the socket we received the message
810  * from had when the netlink socket was created and the sender of the
811  * message has has the capability @cap in all user namespaces.
812  */
813 bool netlink_capable(const struct sk_buff *skb, int cap)
814 {
815         return netlink_ns_capable(skb, &init_user_ns, cap);
816 }
817 EXPORT_SYMBOL(netlink_capable);
818 
819 /**
820  * netlink_net_capable - Netlink network namespace message capability test
821  * @skb: socket buffer holding a netlink command from userspace
822  * @cap: The capability to use
823  *
824  * Test to see if the opener of the socket we received the message
825  * from had when the netlink socket was created and the sender of the
826  * message has has the capability @cap over the network namespace of
827  * the socket we received the message from.
828  */
829 bool netlink_net_capable(const struct sk_buff *skb, int cap)
830 {
831         return netlink_ns_capable(skb, sock_net(skb->sk)->user_ns, cap);
832 }
833 EXPORT_SYMBOL(netlink_net_capable);
834 
835 static inline int netlink_allowed(const struct socket *sock, unsigned int flag)
836 {
837         return (nl_table[sock->sk->sk_protocol].flags & flag) ||
838                 ns_capable(sock_net(sock->sk)->user_ns, CAP_NET_ADMIN);
839 }
840 
841 static void
842 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
843 {
844         struct netlink_sock *nlk = nlk_sk(sk);
845 
846         if (nlk->subscriptions && !subscriptions)
847                 __sk_del_bind_node(sk);
848         else if (!nlk->subscriptions && subscriptions)
849                 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
850         nlk->subscriptions = subscriptions;
851 }
852 
853 static int netlink_realloc_groups(struct sock *sk)
854 {
855         struct netlink_sock *nlk = nlk_sk(sk);
856         unsigned int groups;
857         unsigned long *new_groups;
858         int err = 0;
859 
860         netlink_table_grab();
861 
862         groups = nl_table[sk->sk_protocol].groups;
863         if (!nl_table[sk->sk_protocol].registered) {
864                 err = -ENOENT;
865                 goto out_unlock;
866         }
867 
868         if (nlk->ngroups >= groups)
869                 goto out_unlock;
870 
871         new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
872         if (new_groups == NULL) {
873                 err = -ENOMEM;
874                 goto out_unlock;
875         }
876         memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
877                NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
878 
879         nlk->groups = new_groups;
880         nlk->ngroups = groups;
881  out_unlock:
882         netlink_table_ungrab();
883         return err;
884 }
885 
886 static void netlink_undo_bind(int group, long unsigned int groups,
887                               struct sock *sk)
888 {
889         struct netlink_sock *nlk = nlk_sk(sk);
890         int undo;
891 
892         if (!nlk->netlink_unbind)
893                 return;
894 
895         for (undo = 0; undo < group; undo++)
896                 if (test_bit(undo, &groups))
897                         nlk->netlink_unbind(sock_net(sk), undo + 1);
898 }
899 
900 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
901                         int addr_len)
902 {
903         struct sock *sk = sock->sk;
904         struct net *net = sock_net(sk);
905         struct netlink_sock *nlk = nlk_sk(sk);
906         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
907         int err;
908         long unsigned int groups = nladdr->nl_groups;
909         bool bound;
910 
911         if (addr_len < sizeof(struct sockaddr_nl))
912                 return -EINVAL;
913 
914         if (nladdr->nl_family != AF_NETLINK)
915                 return -EINVAL;
916 
917         /* Only superuser is allowed to listen multicasts */
918         if (groups) {
919                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
920                         return -EPERM;
921                 err = netlink_realloc_groups(sk);
922                 if (err)
923                         return err;
924         }
925 
926         bound = nlk->bound;
927         if (bound) {
928                 /* Ensure nlk->portid is up-to-date. */
929                 smp_rmb();
930 
931                 if (nladdr->nl_pid != nlk->portid)
932                         return -EINVAL;
933         }
934 
935         if (nlk->netlink_bind && groups) {
936                 int group;
937 
938                 for (group = 0; group < nlk->ngroups; group++) {
939                         if (!test_bit(group, &groups))
940                                 continue;
941                         err = nlk->netlink_bind(net, group + 1);
942                         if (!err)
943                                 continue;
944                         netlink_undo_bind(group, groups, sk);
945                         return err;
946                 }
947         }
948 
949         /* No need for barriers here as we return to user-space without
950          * using any of the bound attributes.
951          */
952         if (!bound) {
953                 err = nladdr->nl_pid ?
954                         netlink_insert(sk, nladdr->nl_pid) :
955                         netlink_autobind(sock);
956                 if (err) {
957                         netlink_undo_bind(nlk->ngroups, groups, sk);
958                         return err;
959                 }
960         }
961 
962         if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
963                 return 0;
964 
965         netlink_table_grab();
966         netlink_update_subscriptions(sk, nlk->subscriptions +
967                                          hweight32(groups) -
968                                          hweight32(nlk->groups[0]));
969         nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | groups;
970         netlink_update_listeners(sk);
971         netlink_table_ungrab();
972 
973         return 0;
974 }
975 
976 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
977                            int alen, int flags)
978 {
979         int err = 0;
980         struct sock *sk = sock->sk;
981         struct netlink_sock *nlk = nlk_sk(sk);
982         struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
983 
984         if (alen < sizeof(addr->sa_family))
985                 return -EINVAL;
986 
987         if (addr->sa_family == AF_UNSPEC) {
988                 sk->sk_state    = NETLINK_UNCONNECTED;
989                 nlk->dst_portid = 0;
990                 nlk->dst_group  = 0;
991                 return 0;
992         }
993         if (addr->sa_family != AF_NETLINK)
994                 return -EINVAL;
995 
996         if ((nladdr->nl_groups || nladdr->nl_pid) &&
997             !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
998                 return -EPERM;
999 
1000         /* No need for barriers here as we return to user-space without
1001          * using any of the bound attributes.
1002          */
1003         if (!nlk->bound)
1004                 err = netlink_autobind(sock);
1005 
1006         if (err == 0) {
1007                 sk->sk_state    = NETLINK_CONNECTED;
1008                 nlk->dst_portid = nladdr->nl_pid;
1009                 nlk->dst_group  = ffs(nladdr->nl_groups);
1010         }
1011 
1012         return err;
1013 }
1014 
1015 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
1016                            int *addr_len, int peer)
1017 {
1018         struct sock *sk = sock->sk;
1019         struct netlink_sock *nlk = nlk_sk(sk);
1020         DECLARE_SOCKADDR(struct sockaddr_nl *, nladdr, addr);
1021 
1022         nladdr->nl_family = AF_NETLINK;
1023         nladdr->nl_pad = 0;
1024         *addr_len = sizeof(*nladdr);
1025 
1026         if (peer) {
1027                 nladdr->nl_pid = nlk->dst_portid;
1028                 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
1029         } else {
1030                 nladdr->nl_pid = nlk->portid;
1031                 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
1032         }
1033         return 0;
1034 }
1035 
1036 static int netlink_ioctl(struct socket *sock, unsigned int cmd,
1037                          unsigned long arg)
1038 {
1039         /* try to hand this ioctl down to the NIC drivers.
1040          */
1041         return -ENOIOCTLCMD;
1042 }
1043 
1044 static struct sock *netlink_getsockbyportid(struct sock *ssk, u32 portid)
1045 {
1046         struct sock *sock;
1047         struct netlink_sock *nlk;
1048 
1049         sock = netlink_lookup(sock_net(ssk), ssk->sk_protocol, portid);
1050         if (!sock)
1051                 return ERR_PTR(-ECONNREFUSED);
1052 
1053         /* Don't bother queuing skb if kernel socket has no input function */
1054         nlk = nlk_sk(sock);
1055         if (sock->sk_state == NETLINK_CONNECTED &&
1056             nlk->dst_portid != nlk_sk(ssk)->portid) {
1057                 sock_put(sock);
1058                 return ERR_PTR(-ECONNREFUSED);
1059         }
1060         return sock;
1061 }
1062 
1063 struct sock *netlink_getsockbyfilp(struct file *filp)
1064 {
1065         struct inode *inode = file_inode(filp);
1066         struct sock *sock;
1067 
1068         if (!S_ISSOCK(inode->i_mode))
1069                 return ERR_PTR(-ENOTSOCK);
1070 
1071         sock = SOCKET_I(inode)->sk;
1072         if (sock->sk_family != AF_NETLINK)
1073                 return ERR_PTR(-EINVAL);
1074 
1075         sock_hold(sock);
1076         return sock;
1077 }
1078 
1079 static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
1080                                                int broadcast)
1081 {
1082         struct sk_buff *skb;
1083         void *data;
1084 
1085         if (size <= NLMSG_GOODSIZE || broadcast)
1086                 return alloc_skb(size, GFP_KERNEL);
1087 
1088         size = SKB_DATA_ALIGN(size) +
1089                SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
1090 
1091         data = vmalloc(size);
1092         if (data == NULL)
1093                 return NULL;
1094 
1095         skb = __build_skb(data, size);
1096         if (skb == NULL)
1097                 vfree(data);
1098         else
1099                 skb->destructor = netlink_skb_destructor;
1100 
1101         return skb;
1102 }
1103 
1104 /*
1105  * Attach a skb to a netlink socket.
1106  * The caller must hold a reference to the destination socket. On error, the
1107  * reference is dropped. The skb is not send to the destination, just all
1108  * all error checks are performed and memory in the queue is reserved.
1109  * Return values:
1110  * < 0: error. skb freed, reference to sock dropped.
1111  * 0: continue
1112  * 1: repeat lookup - reference dropped while waiting for socket memory.
1113  */
1114 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
1115                       long *timeo, struct sock *ssk)
1116 {
1117         struct netlink_sock *nlk;
1118 
1119         nlk = nlk_sk(sk);
1120 
1121         if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1122              test_bit(NETLINK_S_CONGESTED, &nlk->state))) {
1123                 DECLARE_WAITQUEUE(wait, current);
1124                 if (!*timeo) {
1125                         if (!ssk || netlink_is_kernel(ssk))
1126                                 netlink_overrun(sk);
1127                         sock_put(sk);
1128                         kfree_skb(skb);
1129                         return -EAGAIN;
1130                 }
1131 
1132                 __set_current_state(TASK_INTERRUPTIBLE);
1133                 add_wait_queue(&nlk->wait, &wait);
1134 
1135                 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
1136                      test_bit(NETLINK_S_CONGESTED, &nlk->state)) &&
1137                     !sock_flag(sk, SOCK_DEAD))
1138                         *timeo = schedule_timeout(*timeo);
1139 
1140                 __set_current_state(TASK_RUNNING);
1141                 remove_wait_queue(&nlk->wait, &wait);
1142                 sock_put(sk);
1143 
1144                 if (signal_pending(current)) {
1145                         kfree_skb(skb);
1146                         return sock_intr_errno(*timeo);
1147                 }
1148                 return 1;
1149         }
1150         netlink_skb_set_owner_r(skb, sk);
1151         return 0;
1152 }
1153 
1154 static int __netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1155 {
1156         int len = skb->len;
1157 
1158         netlink_deliver_tap(skb);
1159 
1160         skb_queue_tail(&sk->sk_receive_queue, skb);
1161         sk->sk_data_ready(sk);
1162         return len;
1163 }
1164 
1165 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
1166 {
1167         int len = __netlink_sendskb(sk, skb);
1168 
1169         sock_put(sk);
1170         return len;
1171 }
1172 
1173 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
1174 {
1175         kfree_skb(skb);
1176         sock_put(sk);
1177 }
1178 
1179 static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
1180 {
1181         int delta;
1182 
1183         WARN_ON(skb->sk != NULL);
1184         delta = skb->end - skb->tail;
1185         if (is_vmalloc_addr(skb->head) || delta * 2 < skb->truesize)
1186                 return skb;
1187 
1188         if (skb_shared(skb)) {
1189                 struct sk_buff *nskb = skb_clone(skb, allocation);
1190                 if (!nskb)
1191                         return skb;
1192                 consume_skb(skb);
1193                 skb = nskb;
1194         }
1195 
1196         if (!pskb_expand_head(skb, 0, -delta, allocation))
1197                 skb->truesize -= delta;
1198 
1199         return skb;
1200 }
1201 
1202 static int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb,
1203                                   struct sock *ssk)
1204 {
1205         int ret;
1206         struct netlink_sock *nlk = nlk_sk(sk);
1207 
1208         ret = -ECONNREFUSED;
1209         if (nlk->netlink_rcv != NULL) {
1210                 ret = skb->len;
1211                 netlink_skb_set_owner_r(skb, sk);
1212                 NETLINK_CB(skb).sk = ssk;
1213                 netlink_deliver_tap_kernel(sk, ssk, skb);
1214                 nlk->netlink_rcv(skb);
1215                 consume_skb(skb);
1216         } else {
1217                 kfree_skb(skb);
1218         }
1219         sock_put(sk);
1220         return ret;
1221 }
1222 
1223 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
1224                     u32 portid, int nonblock)
1225 {
1226         struct sock *sk;
1227         int err;
1228         long timeo;
1229 
1230         skb = netlink_trim(skb, gfp_any());
1231 
1232         timeo = sock_sndtimeo(ssk, nonblock);
1233 retry:
1234         sk = netlink_getsockbyportid(ssk, portid);
1235         if (IS_ERR(sk)) {
1236                 kfree_skb(skb);
1237                 return PTR_ERR(sk);
1238         }
1239         if (netlink_is_kernel(sk))
1240                 return netlink_unicast_kernel(sk, skb, ssk);
1241 
1242         if (sk_filter(sk, skb)) {
1243                 err = skb->len;
1244                 kfree_skb(skb);
1245                 sock_put(sk);
1246                 return err;
1247         }
1248 
1249         err = netlink_attachskb(sk, skb, &timeo, ssk);
1250         if (err == 1)
1251                 goto retry;
1252         if (err)
1253                 return err;
1254 
1255         return netlink_sendskb(sk, skb);
1256 }
1257 EXPORT_SYMBOL(netlink_unicast);
1258 
1259 int netlink_has_listeners(struct sock *sk, unsigned int group)
1260 {
1261         int res = 0;
1262         struct listeners *listeners;
1263 
1264         BUG_ON(!netlink_is_kernel(sk));
1265 
1266         rcu_read_lock();
1267         listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
1268 
1269         if (listeners && group - 1 < nl_table[sk->sk_protocol].groups)
1270                 res = test_bit(group - 1, listeners->masks);
1271 
1272         rcu_read_unlock();
1273 
1274         return res;
1275 }
1276 EXPORT_SYMBOL_GPL(netlink_has_listeners);
1277 
1278 static int netlink_broadcast_deliver(struct sock *sk, struct sk_buff *skb)
1279 {
1280         struct netlink_sock *nlk = nlk_sk(sk);
1281 
1282         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
1283             !test_bit(NETLINK_S_CONGESTED, &nlk->state)) {
1284                 netlink_skb_set_owner_r(skb, sk);
1285                 __netlink_sendskb(sk, skb);
1286                 return atomic_read(&sk->sk_rmem_alloc) > (sk->sk_rcvbuf >> 1);
1287         }
1288         return -1;
1289 }
1290 
1291 struct netlink_broadcast_data {
1292         struct sock *exclude_sk;
1293         struct net *net;
1294         u32 portid;
1295         u32 group;
1296         int failure;
1297         int delivery_failure;
1298         int congested;
1299         int delivered;
1300         gfp_t allocation;
1301         struct sk_buff *skb, *skb2;
1302         int (*tx_filter)(struct sock *dsk, struct sk_buff *skb, void *data);
1303         void *tx_data;
1304 };
1305 
1306 static void do_one_broadcast(struct sock *sk,
1307                                     struct netlink_broadcast_data *p)
1308 {
1309         struct netlink_sock *nlk = nlk_sk(sk);
1310         int val;
1311 
1312         if (p->exclude_sk == sk)
1313                 return;
1314 
1315         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1316             !test_bit(p->group - 1, nlk->groups))
1317                 return;
1318 
1319         if (!net_eq(sock_net(sk), p->net)) {
1320                 if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID))
1321                         return;
1322 
1323                 if (!peernet_has_id(sock_net(sk), p->net))
1324                         return;
1325 
1326                 if (!file_ns_capable(sk->sk_socket->file, p->net->user_ns,
1327                                      CAP_NET_BROADCAST))
1328                         return;
1329         }
1330 
1331         if (p->failure) {
1332                 netlink_overrun(sk);
1333                 return;
1334         }
1335 
1336         sock_hold(sk);
1337         if (p->skb2 == NULL) {
1338                 if (skb_shared(p->skb)) {
1339                         p->skb2 = skb_clone(p->skb, p->allocation);
1340                 } else {
1341                         p->skb2 = skb_get(p->skb);
1342                         /*
1343                          * skb ownership may have been set when
1344                          * delivered to a previous socket.
1345                          */
1346                         skb_orphan(p->skb2);
1347                 }
1348         }
1349         if (p->skb2 == NULL) {
1350                 netlink_overrun(sk);
1351                 /* Clone failed. Notify ALL listeners. */
1352                 p->failure = 1;
1353                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1354                         p->delivery_failure = 1;
1355                 goto out;
1356         }
1357         if (p->tx_filter && p->tx_filter(sk, p->skb2, p->tx_data)) {
1358                 kfree_skb(p->skb2);
1359                 p->skb2 = NULL;
1360                 goto out;
1361         }
1362         if (sk_filter(sk, p->skb2)) {
1363                 kfree_skb(p->skb2);
1364                 p->skb2 = NULL;
1365                 goto out;
1366         }
1367         NETLINK_CB(p->skb2).nsid = peernet2id(sock_net(sk), p->net);
1368         NETLINK_CB(p->skb2).nsid_is_set = true;
1369         val = netlink_broadcast_deliver(sk, p->skb2);
1370         if (val < 0) {
1371                 netlink_overrun(sk);
1372                 if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
1373                         p->delivery_failure = 1;
1374         } else {
1375                 p->congested |= val;
1376                 p->delivered = 1;
1377                 p->skb2 = NULL;
1378         }
1379 out:
1380         sock_put(sk);
1381 }
1382 
1383 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb, u32 portid,
1384         u32 group, gfp_t allocation,
1385         int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
1386         void *filter_data)
1387 {
1388         struct net *net = sock_net(ssk);
1389         struct netlink_broadcast_data info;
1390         struct sock *sk;
1391 
1392         skb = netlink_trim(skb, allocation);
1393 
1394         info.exclude_sk = ssk;
1395         info.net = net;
1396         info.portid = portid;
1397         info.group = group;
1398         info.failure = 0;
1399         info.delivery_failure = 0;
1400         info.congested = 0;
1401         info.delivered = 0;
1402         info.allocation = allocation;
1403         info.skb = skb;
1404         info.skb2 = NULL;
1405         info.tx_filter = filter;
1406         info.tx_data = filter_data;
1407 
1408         /* While we sleep in clone, do not allow to change socket list */
1409 
1410         netlink_lock_table();
1411 
1412         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1413                 do_one_broadcast(sk, &info);
1414 
1415         consume_skb(skb);
1416 
1417         netlink_unlock_table();
1418 
1419         if (info.delivery_failure) {
1420                 kfree_skb(info.skb2);
1421                 return -ENOBUFS;
1422         }
1423         consume_skb(info.skb2);
1424 
1425         if (info.delivered) {
1426                 if (info.congested && gfpflags_allow_blocking(allocation))
1427                         yield();
1428                 return 0;
1429         }
1430         return -ESRCH;
1431 }
1432 EXPORT_SYMBOL(netlink_broadcast_filtered);
1433 
1434 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 portid,
1435                       u32 group, gfp_t allocation)
1436 {
1437         return netlink_broadcast_filtered(ssk, skb, portid, group, allocation,
1438                 NULL, NULL);
1439 }
1440 EXPORT_SYMBOL(netlink_broadcast);
1441 
1442 struct netlink_set_err_data {
1443         struct sock *exclude_sk;
1444         u32 portid;
1445         u32 group;
1446         int code;
1447 };
1448 
1449 static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
1450 {
1451         struct netlink_sock *nlk = nlk_sk(sk);
1452         int ret = 0;
1453 
1454         if (sk == p->exclude_sk)
1455                 goto out;
1456 
1457         if (!net_eq(sock_net(sk), sock_net(p->exclude_sk)))
1458                 goto out;
1459 
1460         if (nlk->portid == p->portid || p->group - 1 >= nlk->ngroups ||
1461             !test_bit(p->group - 1, nlk->groups))
1462                 goto out;
1463 
1464         if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) {
1465                 ret = 1;
1466                 goto out;
1467         }
1468 
1469         sk->sk_err = p->code;
1470         sk->sk_error_report(sk);
1471 out:
1472         return ret;
1473 }
1474 
1475 /**
1476  * netlink_set_err - report error to broadcast listeners
1477  * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
1478  * @portid: the PORTID of a process that we want to skip (if any)
1479  * @group: the broadcast group that will notice the error
1480  * @code: error code, must be negative (as usual in kernelspace)
1481  *
1482  * This function returns the number of broadcast listeners that have set the
1483  * NETLINK_NO_ENOBUFS socket option.
1484  */
1485 int netlink_set_err(struct sock *ssk, u32 portid, u32 group, int code)
1486 {
1487         struct netlink_set_err_data info;
1488         struct sock *sk;
1489         int ret = 0;
1490 
1491         info.exclude_sk = ssk;
1492         info.portid = portid;
1493         info.group = group;
1494         /* sk->sk_err wants a positive error value */
1495         info.code = -code;
1496 
1497         read_lock(&nl_table_lock);
1498 
1499         sk_for_each_bound(sk, &nl_table[ssk->sk_protocol].mc_list)
1500                 ret += do_one_set_err(sk, &info);
1501 
1502         read_unlock(&nl_table_lock);
1503         return ret;
1504 }
1505 EXPORT_SYMBOL(netlink_set_err);
1506 
1507 /* must be called with netlink table grabbed */
1508 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1509                                      unsigned int group,
1510                                      int is_new)
1511 {
1512         int old, new = !!is_new, subscriptions;
1513 
1514         old = test_bit(group - 1, nlk->groups);
1515         subscriptions = nlk->subscriptions - old + new;
1516         if (new)
1517                 __set_bit(group - 1, nlk->groups);
1518         else
1519                 __clear_bit(group - 1, nlk->groups);
1520         netlink_update_subscriptions(&nlk->sk, subscriptions);
1521         netlink_update_listeners(&nlk->sk);
1522 }
1523 
1524 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1525                               char __user *optval, unsigned int optlen)
1526 {
1527         struct sock *sk = sock->sk;
1528         struct netlink_sock *nlk = nlk_sk(sk);
1529         unsigned int val = 0;
1530         int err;
1531 
1532         if (level != SOL_NETLINK)
1533                 return -ENOPROTOOPT;
1534 
1535         if (optlen >= sizeof(int) &&
1536             get_user(val, (unsigned int __user *)optval))
1537                 return -EFAULT;
1538 
1539         switch (optname) {
1540         case NETLINK_PKTINFO:
1541                 if (val)
1542                         nlk->flags |= NETLINK_F_RECV_PKTINFO;
1543                 else
1544                         nlk->flags &= ~NETLINK_F_RECV_PKTINFO;
1545                 err = 0;
1546                 break;
1547         case NETLINK_ADD_MEMBERSHIP:
1548         case NETLINK_DROP_MEMBERSHIP: {
1549                 if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
1550                         return -EPERM;
1551                 err = netlink_realloc_groups(sk);
1552                 if (err)
1553                         return err;
1554                 if (!val || val - 1 >= nlk->ngroups)
1555                         return -EINVAL;
1556                 if (optname == NETLINK_ADD_MEMBERSHIP && nlk->netlink_bind) {
1557                         err = nlk->netlink_bind(sock_net(sk), val);
1558                         if (err)
1559                                 return err;
1560                 }
1561                 netlink_table_grab();
1562                 netlink_update_socket_mc(nlk, val,
1563                                          optname == NETLINK_ADD_MEMBERSHIP);
1564                 netlink_table_ungrab();
1565                 if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
1566                         nlk->netlink_unbind(sock_net(sk), val);
1567 
1568                 err = 0;
1569                 break;
1570         }
1571         case NETLINK_BROADCAST_ERROR:
1572                 if (val)
1573                         nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR;
1574                 else
1575                         nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR;
1576                 err = 0;
1577                 break;
1578         case NETLINK_NO_ENOBUFS:
1579                 if (val) {
1580                         nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS;
1581                         clear_bit(NETLINK_S_CONGESTED, &nlk->state);
1582                         wake_up_interruptible(&nlk->wait);
1583                 } else {
1584                         nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS;
1585                 }
1586                 err = 0;
1587                 break;
1588         case NETLINK_LISTEN_ALL_NSID:
1589                 if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
1590                         return -EPERM;
1591 
1592                 if (val)
1593                         nlk->flags |= NETLINK_F_LISTEN_ALL_NSID;
1594                 else
1595                         nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
1596                 err = 0;
1597                 break;
1598         case NETLINK_CAP_ACK:
1599                 if (val)
1600                         nlk->flags |= NETLINK_F_CAP_ACK;
1601                 else
1602                         nlk->flags &= ~NETLINK_F_CAP_ACK;
1603                 err = 0;
1604                 break;
1605         default:
1606                 err = -ENOPROTOOPT;
1607         }
1608         return err;
1609 }
1610 
1611 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1612                               char __user *optval, int __user *optlen)
1613 {
1614         struct sock *sk = sock->sk;
1615         struct netlink_sock *nlk = nlk_sk(sk);
1616         int len, val, err;
1617 
1618         if (level != SOL_NETLINK)
1619                 return -ENOPROTOOPT;
1620 
1621         if (get_user(len, optlen))
1622                 return -EFAULT;
1623         if (len < 0)
1624                 return -EINVAL;
1625 
1626         switch (optname) {
1627         case NETLINK_PKTINFO:
1628                 if (len < sizeof(int))
1629                         return -EINVAL;
1630                 len = sizeof(int);
1631                 val = nlk->flags & NETLINK_F_RECV_PKTINFO ? 1 : 0;
1632                 if (put_user(len, optlen) ||
1633                     put_user(val, optval))
1634                         return -EFAULT;
1635                 err = 0;
1636                 break;
1637         case NETLINK_BROADCAST_ERROR:
1638                 if (len < sizeof(int))
1639                         return -EINVAL;
1640                 len = sizeof(int);
1641                 val = nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR ? 1 : 0;
1642                 if (put_user(len, optlen) ||
1643                     put_user(val, optval))
1644                         return -EFAULT;
1645                 err = 0;
1646                 break;
1647         case NETLINK_NO_ENOBUFS:
1648                 if (len < sizeof(int))
1649                         return -EINVAL;
1650                 len = sizeof(int);
1651                 val = nlk->flags & NETLINK_F_RECV_NO_ENOBUFS ? 1 : 0;
1652                 if (put_user(len, optlen) ||
1653                     put_user(val, optval))
1654                         return -EFAULT;
1655                 err = 0;
1656                 break;
1657         case NETLINK_LIST_MEMBERSHIPS: {
1658                 int pos, idx, shift;
1659 
1660                 err = 0;
1661                 netlink_lock_table();
1662                 for (pos = 0; pos * 8 < nlk->ngroups; pos += sizeof(u32)) {
1663                         if (len - pos < sizeof(u32))
1664                                 break;
1665 
1666                         idx = pos / sizeof(unsigned long);
1667                         shift = (pos % sizeof(unsigned long)) * 8;
1668                         if (put_user((u32)(nlk->groups[idx] >> shift),
1669                                      (u32 __user *)(optval + pos))) {
1670                                 err = -EFAULT;
1671                                 break;
1672                         }
1673                 }
1674                 if (put_user(ALIGN(nlk->ngroups / 8, sizeof(u32)), optlen))
1675                         err = -EFAULT;
1676                 netlink_unlock_table();
1677                 break;
1678         }
1679         case NETLINK_CAP_ACK:
1680                 if (len < sizeof(int))
1681                         return -EINVAL;
1682                 len = sizeof(int);
1683                 val = nlk->flags & NETLINK_F_CAP_ACK ? 1 : 0;
1684                 if (put_user(len, optlen) ||
1685                     put_user(val, optval))
1686                         return -EFAULT;
1687                 err = 0;
1688                 break;
1689         default:
1690                 err = -ENOPROTOOPT;
1691         }
1692         return err;
1693 }
1694 
1695 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1696 {
1697         struct nl_pktinfo info;
1698 
1699         info.group = NETLINK_CB(skb).dst_group;
1700         put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1701 }
1702 
1703 static void netlink_cmsg_listen_all_nsid(struct sock *sk, struct msghdr *msg,
1704                                          struct sk_buff *skb)
1705 {
1706         if (!NETLINK_CB(skb).nsid_is_set)
1707                 return;
1708 
1709         put_cmsg(msg, SOL_NETLINK, NETLINK_LISTEN_ALL_NSID, sizeof(int),
1710                  &NETLINK_CB(skb).nsid);
1711 }
1712 
1713 static int netlink_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
1714 {
1715         struct sock *sk = sock->sk;
1716         struct netlink_sock *nlk = nlk_sk(sk);
1717         DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1718         u32 dst_portid;
1719         u32 dst_group;
1720         struct sk_buff *skb;
1721         int err;
1722         struct scm_cookie scm;
1723         u32 netlink_skb_flags = 0;
1724 
1725         if (msg->msg_flags&MSG_OOB)
1726                 return -EOPNOTSUPP;
1727 
1728         err = scm_send(sock, msg, &scm, true);
1729         if (err < 0)
1730                 return err;
1731 
1732         if (msg->msg_namelen) {
1733                 err = -EINVAL;
1734                 if (addr->nl_family != AF_NETLINK)
1735                         goto out;
1736                 dst_portid = addr->nl_pid;
1737                 dst_group = ffs(addr->nl_groups);
1738                 err =  -EPERM;
1739                 if ((dst_group || dst_portid) &&
1740                     !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
1741                         goto out;
1742                 netlink_skb_flags |= NETLINK_SKB_DST;
1743         } else {
1744                 dst_portid = nlk->dst_portid;
1745                 dst_group = nlk->dst_group;
1746         }
1747 
1748         if (!nlk->bound) {
1749                 err = netlink_autobind(sock);
1750                 if (err)
1751                         goto out;
1752         } else {
1753                 /* Ensure nlk is hashed and visible. */
1754                 smp_rmb();
1755         }
1756 
1757         err = -EMSGSIZE;
1758         if (len > sk->sk_sndbuf - 32)
1759                 goto out;
1760         err = -ENOBUFS;
1761         skb = netlink_alloc_large_skb(len, dst_group);
1762         if (skb == NULL)
1763                 goto out;
1764 
1765         NETLINK_CB(skb).portid  = nlk->portid;
1766         NETLINK_CB(skb).dst_group = dst_group;
1767         NETLINK_CB(skb).creds   = scm.creds;
1768         NETLINK_CB(skb).flags   = netlink_skb_flags;
1769 
1770         err = -EFAULT;
1771         if (memcpy_from_msg(skb_put(skb, len), msg, len)) {
1772                 kfree_skb(skb);
1773                 goto out;
1774         }
1775 
1776         err = security_netlink_send(sk, skb);
1777         if (err) {
1778                 kfree_skb(skb);
1779                 goto out;
1780         }
1781 
1782         if (dst_group) {
1783                 atomic_inc(&skb->users);
1784                 netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
1785         }
1786         err = netlink_unicast(sk, skb, dst_portid, msg->msg_flags&MSG_DONTWAIT);
1787 
1788 out:
1789         scm_destroy(&scm);
1790         return err;
1791 }
1792 
1793 static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
1794                            int flags)
1795 {
1796         struct scm_cookie scm;
1797         struct sock *sk = sock->sk;
1798         struct netlink_sock *nlk = nlk_sk(sk);
1799         int noblock = flags&MSG_DONTWAIT;
1800         size_t copied;
1801         struct sk_buff *skb, *data_skb;
1802         int err, ret;
1803 
1804         if (flags&MSG_OOB)
1805                 return -EOPNOTSUPP;
1806 
1807         copied = 0;
1808 
1809         skb = skb_recv_datagram(sk, flags, noblock, &err);
1810         if (skb == NULL)
1811                 goto out;
1812 
1813         data_skb = skb;
1814 
1815 #ifdef CONFIG_COMPAT_NETLINK_MESSAGES
1816         if (unlikely(skb_shinfo(skb)->frag_list)) {
1817                 /*
1818                  * If this skb has a frag_list, then here that means that we
1819                  * will have to use the frag_list skb's data for compat tasks
1820                  * and the regular skb's data for normal (non-compat) tasks.
1821                  *
1822                  * If we need to send the compat skb, assign it to the
1823                  * 'data_skb' variable so that it will be used below for data
1824                  * copying. We keep 'skb' for everything else, including
1825                  * freeing both later.
1826                  */
1827                 if (flags & MSG_CMSG_COMPAT)
1828                         data_skb = skb_shinfo(skb)->frag_list;
1829         }
1830 #endif
1831 
1832         /* Record the max length of recvmsg() calls for future allocations */
1833         nlk->max_recvmsg_len = max(nlk->max_recvmsg_len, len);
1834         nlk->max_recvmsg_len = min_t(size_t, nlk->max_recvmsg_len,
1835                                      16384);
1836 
1837         copied = data_skb->len;
1838         if (len < copied) {
1839                 msg->msg_flags |= MSG_TRUNC;
1840                 copied = len;
1841         }
1842 
1843         skb_reset_transport_header(data_skb);
1844         err = skb_copy_datagram_msg(data_skb, 0, msg, copied);
1845 
1846         if (msg->msg_name) {
1847                 DECLARE_SOCKADDR(struct sockaddr_nl *, addr, msg->msg_name);
1848                 addr->nl_family = AF_NETLINK;
1849                 addr->nl_pad    = 0;
1850                 addr->nl_pid    = NETLINK_CB(skb).portid;
1851                 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1852                 msg->msg_namelen = sizeof(*addr);
1853         }
1854 
1855         if (nlk->flags & NETLINK_F_RECV_PKTINFO)
1856                 netlink_cmsg_recv_pktinfo(msg, skb);
1857         if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
1858                 netlink_cmsg_listen_all_nsid(sk, msg, skb);
1859 
1860         memset(&scm, 0, sizeof(scm));
1861         scm.creds = *NETLINK_CREDS(skb);
1862         if (flags & MSG_TRUNC)
1863                 copied = data_skb->len;
1864 
1865         skb_free_datagram(sk, skb);
1866 
1867         if (nlk->cb_running &&
1868             atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
1869                 ret = netlink_dump(sk);
1870                 if (ret) {
1871                         sk->sk_err = -ret;
1872                         sk->sk_error_report(sk);
1873                 }
1874         }
1875 
1876         scm_recv(sock, msg, &scm, flags);
1877 out:
1878         netlink_rcv_wake(sk);
1879         return err ? : copied;
1880 }
1881 
1882 static void netlink_data_ready(struct sock *sk)
1883 {
1884         BUG();
1885 }
1886 
1887 /*
1888  *      We export these functions to other modules. They provide a
1889  *      complete set of kernel non-blocking support for message
1890  *      queueing.
1891  */
1892 
1893 struct sock *
1894 __netlink_kernel_create(struct net *net, int unit, struct module *module,
1895                         struct netlink_kernel_cfg *cfg)
1896 {
1897         struct socket *sock;
1898         struct sock *sk;
1899         struct netlink_sock *nlk;
1900         struct listeners *listeners = NULL;
1901         struct mutex *cb_mutex = cfg ? cfg->cb_mutex : NULL;
1902         unsigned int groups;
1903 
1904         BUG_ON(!nl_table);
1905 
1906         if (unit < 0 || unit >= MAX_LINKS)
1907                 return NULL;
1908 
1909         if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
1910                 return NULL;
1911 
1912         if (__netlink_create(net, sock, cb_mutex, unit, 1) < 0)
1913                 goto out_sock_release_nosk;
1914 
1915         sk = sock->sk;
1916 
1917         if (!cfg || cfg->groups < 32)
1918                 groups = 32;
1919         else
1920                 groups = cfg->groups;
1921 
1922         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
1923         if (!listeners)
1924                 goto out_sock_release;
1925 
1926         sk->sk_data_ready = netlink_data_ready;
1927         if (cfg && cfg->input)
1928                 nlk_sk(sk)->netlink_rcv = cfg->input;
1929 
1930         if (netlink_insert(sk, 0))
1931                 goto out_sock_release;
1932 
1933         nlk = nlk_sk(sk);
1934         nlk->flags |= NETLINK_F_KERNEL_SOCKET;
1935 
1936         netlink_table_grab();
1937         if (!nl_table[unit].registered) {
1938                 nl_table[unit].groups = groups;
1939                 rcu_assign_pointer(nl_table[unit].listeners, listeners);
1940                 nl_table[unit].cb_mutex = cb_mutex;
1941                 nl_table[unit].module = module;
1942                 if (cfg) {
1943                         nl_table[unit].bind = cfg->bind;
1944                         nl_table[unit].unbind = cfg->unbind;
1945                         nl_table[unit].flags = cfg->flags;
1946                         if (cfg->compare)
1947                                 nl_table[unit].compare = cfg->compare;
1948                 }
1949                 nl_table[unit].registered = 1;
1950         } else {
1951                 kfree(listeners);
1952                 nl_table[unit].registered++;
1953         }
1954         netlink_table_ungrab();
1955         return sk;
1956 
1957 out_sock_release:
1958         kfree(listeners);
1959         netlink_kernel_release(sk);
1960         return NULL;
1961 
1962 out_sock_release_nosk:
1963         sock_release(sock);
1964         return NULL;
1965 }
1966 EXPORT_SYMBOL(__netlink_kernel_create);
1967 
1968 void
1969 netlink_kernel_release(struct sock *sk)
1970 {
1971         if (sk == NULL || sk->sk_socket == NULL)
1972                 return;
1973 
1974         sock_release(sk->sk_socket);
1975 }
1976 EXPORT_SYMBOL(netlink_kernel_release);
1977 
1978 int __netlink_change_ngroups(struct sock *sk, unsigned int groups)
1979 {
1980         struct listeners *new, *old;
1981         struct netlink_table *tbl = &nl_table[sk->sk_protocol];
1982 
1983         if (groups < 32)
1984                 groups = 32;
1985 
1986         if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
1987                 new = kzalloc(sizeof(*new) + NLGRPSZ(groups), GFP_ATOMIC);
1988                 if (!new)
1989                         return -ENOMEM;
1990                 old = nl_deref_protected(tbl->listeners);
1991                 memcpy(new->masks, old->masks, NLGRPSZ(tbl->groups));
1992                 rcu_assign_pointer(tbl->listeners, new);
1993 
1994                 kfree_rcu(old, rcu);
1995         }
1996         tbl->groups = groups;
1997 
1998         return 0;
1999 }
2000 
2001 /**
2002  * netlink_change_ngroups - change number of multicast groups
2003  *
2004  * This changes the number of multicast groups that are available
2005  * on a certain netlink family. Note that it is not possible to
2006  * change the number of groups to below 32. Also note that it does
2007  * not implicitly call netlink_clear_multicast_users() when the
2008  * number of groups is reduced.
2009  *
2010  * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
2011  * @groups: The new number of groups.
2012  */
2013 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
2014 {
2015         int err;
2016 
2017         netlink_table_grab();
2018         err = __netlink_change_ngroups(sk, groups);
2019         netlink_table_ungrab();
2020 
2021         return err;
2022 }
2023 
2024 void __netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
2025 {
2026         struct sock *sk;
2027         struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
2028 
2029         sk_for_each_bound(sk, &tbl->mc_list)
2030                 netlink_update_socket_mc(nlk_sk(sk), group, 0);
2031 }
2032 
2033 struct nlmsghdr *
2034 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags)
2035 {
2036         struct nlmsghdr *nlh;
2037         int size = nlmsg_msg_size(len);
2038 
2039         nlh = (struct nlmsghdr *)skb_put(skb, NLMSG_ALIGN(size));
2040         nlh->nlmsg_type = type;
2041         nlh->nlmsg_len = size;
2042         nlh->nlmsg_flags = flags;
2043         nlh->nlmsg_pid = portid;
2044         nlh->nlmsg_seq = seq;
2045         if (!__builtin_constant_p(size) || NLMSG_ALIGN(size) - size != 0)
2046                 memset(nlmsg_data(nlh) + len, 0, NLMSG_ALIGN(size) - size);
2047         return nlh;
2048 }
2049 EXPORT_SYMBOL(__nlmsg_put);
2050 
2051 /*
2052  * It looks a bit ugly.
2053  * It would be better to create kernel thread.
2054  */
2055 
2056 static int netlink_dump(struct sock *sk)
2057 {
2058         struct netlink_sock *nlk = nlk_sk(sk);
2059         struct netlink_callback *cb;
2060         struct sk_buff *skb = NULL;
2061         struct nlmsghdr *nlh;
2062         struct module *module;
2063         int len, err = -ENOBUFS;
2064         int alloc_min_size;
2065         int alloc_size;
2066 
2067         mutex_lock(nlk->cb_mutex);
2068         if (!nlk->cb_running) {
2069                 err = -EINVAL;
2070                 goto errout_skb;
2071         }
2072 
2073         if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
2074                 goto errout_skb;
2075 
2076         /* NLMSG_GOODSIZE is small to avoid high order allocations being
2077          * required, but it makes sense to _attempt_ a 16K bytes allocation
2078          * to reduce number of system calls on dump operations, if user
2079          * ever provided a big enough buffer.
2080          */
2081         cb = &nlk->cb;
2082         alloc_min_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
2083 
2084         if (alloc_min_size < nlk->max_recvmsg_len) {
2085                 alloc_size = nlk->max_recvmsg_len;
2086                 skb = alloc_skb(alloc_size, GFP_KERNEL |
2087                                             __GFP_NOWARN | __GFP_NORETRY);
2088         }
2089         if (!skb) {
2090                 alloc_size = alloc_min_size;
2091                 skb = alloc_skb(alloc_size, GFP_KERNEL);
2092         }
2093         if (!skb)
2094                 goto errout_skb;
2095 
2096         /* Trim skb to allocated size. User is expected to provide buffer as
2097          * large as max(min_dump_alloc, 16KiB (mac_recvmsg_len capped at
2098          * netlink_recvmsg())). dump will pack as many smaller messages as
2099          * could fit within the allocated skb. skb is typically allocated
2100          * with larger space than required (could be as much as near 2x the
2101          * requested size with align to next power of 2 approach). Allowing
2102          * dump to use the excess space makes it difficult for a user to have a
2103          * reasonable static buffer based on the expected largest dump of a
2104          * single netdev. The outcome is MSG_TRUNC error.
2105          */
2106         skb_reserve(skb, skb_tailroom(skb) - alloc_size);
2107         netlink_skb_set_owner_r(skb, sk);
2108 
2109         len = cb->dump(skb, cb);
2110 
2111         if (len > 0) {
2112                 mutex_unlock(nlk->cb_mutex);
2113 
2114                 if (sk_filter(sk, skb))
2115                         kfree_skb(skb);
2116                 else
2117                         __netlink_sendskb(sk, skb);
2118                 return 0;
2119         }
2120 
2121         nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
2122         if (!nlh)
2123                 goto errout_skb;
2124 
2125         nl_dump_check_consistent(cb, nlh);
2126 
2127         memcpy(nlmsg_data(nlh), &len, sizeof(len));
2128 
2129         if (sk_filter(sk, skb))
2130                 kfree_skb(skb);
2131         else
2132                 __netlink_sendskb(sk, skb);
2133 
2134         if (cb->done)
2135                 cb->done(cb);
2136 
2137         nlk->cb_running = false;
2138         module = cb->module;
2139         skb = cb->skb;
2140         mutex_unlock(nlk->cb_mutex);
2141         module_put(module);
2142         consume_skb(skb);
2143         return 0;
2144 
2145 errout_skb:
2146         mutex_unlock(nlk->cb_mutex);
2147         kfree_skb(skb);
2148         return err;
2149 }
2150 
2151 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
2152                          const struct nlmsghdr *nlh,
2153                          struct netlink_dump_control *control)
2154 {
2155         struct netlink_callback *cb;
2156         struct sock *sk;
2157         struct netlink_sock *nlk;
2158         int ret;
2159 
2160         atomic_inc(&skb->users);
2161 
2162         sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
2163         if (sk == NULL) {
2164                 ret = -ECONNREFUSED;
2165                 goto error_free;
2166         }
2167 
2168         nlk = nlk_sk(sk);
2169         mutex_lock(nlk->cb_mutex);
2170         /* A dump is in progress... */
2171         if (nlk->cb_running) {
2172                 ret = -EBUSY;
2173                 goto error_unlock;
2174         }
2175         /* add reference of module which cb->dump belongs to */
2176         if (!try_module_get(control->module)) {
2177                 ret = -EPROTONOSUPPORT;
2178                 goto error_unlock;
2179         }
2180 
2181         cb = &nlk->cb;
2182         memset(cb, 0, sizeof(*cb));
2183         cb->start = control->start;
2184         cb->dump = control->dump;
2185         cb->done = control->done;
2186         cb->nlh = nlh;
2187         cb->data = control->data;
2188         cb->module = control->module;
2189         cb->min_dump_alloc = control->min_dump_alloc;
2190         cb->skb = skb;
2191 
2192         nlk->cb_running = true;
2193 
2194         mutex_unlock(nlk->cb_mutex);
2195 
2196         if (cb->start)
2197                 cb->start(cb);
2198 
2199         ret = netlink_dump(sk);
2200         sock_put(sk);
2201 
2202         if (ret)
2203                 return ret;
2204 
2205         /* We successfully started a dump, by returning -EINTR we
2206          * signal not to send ACK even if it was requested.
2207          */
2208         return -EINTR;
2209 
2210 error_unlock:
2211         sock_put(sk);
2212         mutex_unlock(nlk->cb_mutex);
2213 error_free:
2214         kfree_skb(skb);
2215         return ret;
2216 }
2217 EXPORT_SYMBOL(__netlink_dump_start);
2218 
2219 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
2220 {
2221         struct sk_buff *skb;
2222         struct nlmsghdr *rep;
2223         struct nlmsgerr *errmsg;
2224         size_t payload = sizeof(*errmsg);
2225         struct netlink_sock *nlk = nlk_sk(NETLINK_CB(in_skb).sk);
2226 
2227         /* Error messages get the original request appened, unless the user
2228          * requests to cap the error message.
2229          */
2230         if (!(nlk->flags & NETLINK_F_CAP_ACK) && err)
2231                 payload += nlmsg_len(nlh);
2232 
2233         skb = nlmsg_new(payload, GFP_KERNEL);
2234         if (!skb) {
2235                 struct sock *sk;
2236 
2237                 sk = netlink_lookup(sock_net(in_skb->sk),
2238                                     in_skb->sk->sk_protocol,
2239                                     NETLINK_CB(in_skb).portid);
2240                 if (sk) {
2241                         sk->sk_err = ENOBUFS;
2242                         sk->sk_error_report(sk);
2243                         sock_put(sk);
2244                 }
2245                 return;
2246         }
2247 
2248         rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
2249                           NLMSG_ERROR, payload, 0);
2250         errmsg = nlmsg_data(rep);
2251         errmsg->error = err;
2252         memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
2253         netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid, MSG_DONTWAIT);
2254 }
2255 EXPORT_SYMBOL(netlink_ack);
2256 
2257 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
2258                                                      struct nlmsghdr *))
2259 {
2260         struct nlmsghdr *nlh;
2261         int err;
2262 
2263         while (skb->len >= nlmsg_total_size(0)) {
2264                 int msglen;
2265 
2266                 nlh = nlmsg_hdr(skb);
2267                 err = 0;
2268 
2269                 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
2270                         return 0;
2271 
2272                 /* Only requests are handled by the kernel */
2273                 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
2274                         goto ack;
2275 
2276                 /* Skip control messages */
2277                 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
2278                         goto ack;
2279 
2280                 err = cb(skb, nlh);
2281                 if (err == -EINTR)
2282                         goto skip;
2283 
2284 ack:
2285                 if (nlh->nlmsg_flags & NLM_F_ACK || err)
2286                         netlink_ack(skb, nlh, err);
2287 
2288 skip:
2289                 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
2290                 if (msglen > skb->len)
2291                         msglen = skb->len;
2292                 skb_pull(skb, msglen);
2293         }
2294 
2295         return 0;
2296 }
2297 EXPORT_SYMBOL(netlink_rcv_skb);
2298 
2299 /**
2300  * nlmsg_notify - send a notification netlink message
2301  * @sk: netlink socket to use
2302  * @skb: notification message
2303  * @portid: destination netlink portid for reports or 0
2304  * @group: destination multicast group or 0
2305  * @report: 1 to report back, 0 to disable
2306  * @flags: allocation flags
2307  */
2308 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
2309                  unsigned int group, int report, gfp_t flags)
2310 {
2311         int err = 0;
2312 
2313         if (group) {
2314                 int exclude_portid = 0;
2315 
2316                 if (report) {
2317                         atomic_inc(&skb->users);
2318                         exclude_portid = portid;
2319                 }
2320 
2321                 /* errors reported via destination sk->sk_err, but propagate
2322                  * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
2323                 err = nlmsg_multicast(sk, skb, exclude_portid, group, flags);
2324         }
2325 
2326         if (report) {
2327                 int err2;
2328 
2329                 err2 = nlmsg_unicast(sk, skb, portid);
2330                 if (!err || err == -ESRCH)
2331                         err = err2;
2332         }
2333 
2334         return err;
2335 }
2336 EXPORT_SYMBOL(nlmsg_notify);
2337 
2338 #ifdef CONFIG_PROC_FS
2339 struct nl_seq_iter {
2340         struct seq_net_private p;
2341         struct rhashtable_iter hti;
2342         int link;
2343 };
2344 
2345 static int netlink_walk_start(struct nl_seq_iter *iter)
2346 {
2347         int err;
2348 
2349         err = rhashtable_walk_init(&nl_table[iter->link].hash, &iter->hti,
2350                                    GFP_KERNEL);
2351         if (err) {
2352                 iter->link = MAX_LINKS;
2353                 return err;
2354         }
2355 
2356         err = rhashtable_walk_start(&iter->hti);
2357         return err == -EAGAIN ? 0 : err;
2358 }
2359 
2360 static void netlink_walk_stop(struct nl_seq_iter *iter)
2361 {
2362         rhashtable_walk_stop(&iter->hti);
2363         rhashtable_walk_exit(&iter->hti);
2364 }
2365 
2366 static void *__netlink_seq_next(struct seq_file *seq)
2367 {
2368         struct nl_seq_iter *iter = seq->private;
2369         struct netlink_sock *nlk;
2370 
2371         do {
2372                 for (;;) {
2373                         int err;
2374 
2375                         nlk = rhashtable_walk_next(&iter->hti);
2376 
2377                         if (IS_ERR(nlk)) {
2378                                 if (PTR_ERR(nlk) == -EAGAIN)
2379                                         continue;
2380 
2381                                 return nlk;
2382                         }
2383 
2384                         if (nlk)
2385                                 break;
2386 
2387                         netlink_walk_stop(iter);
2388                         if (++iter->link >= MAX_LINKS)
2389                                 return NULL;
2390 
2391                         err = netlink_walk_start(iter);
2392                         if (err)
2393                                 return ERR_PTR(err);
2394                 }
2395         } while (sock_net(&nlk->sk) != seq_file_net(seq));
2396 
2397         return nlk;
2398 }
2399 
2400 static void *netlink_seq_start(struct seq_file *seq, loff_t *posp)
2401 {
2402         struct nl_seq_iter *iter = seq->private;
2403         void *obj = SEQ_START_TOKEN;
2404         loff_t pos;
2405         int err;
2406 
2407         iter->link = 0;
2408 
2409         err = netlink_walk_start(iter);
2410         if (err)
2411                 return ERR_PTR(err);
2412 
2413         for (pos = *posp; pos && obj && !IS_ERR(obj); pos--)
2414                 obj = __netlink_seq_next(seq);
2415 
2416         return obj;
2417 }
2418 
2419 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2420 {
2421         ++*pos;
2422         return __netlink_seq_next(seq);
2423 }
2424 
2425 static void netlink_seq_stop(struct seq_file *seq, void *v)
2426 {
2427         struct nl_seq_iter *iter = seq->private;
2428 
2429         if (iter->link >= MAX_LINKS)
2430                 return;
2431 
2432         netlink_walk_stop(iter);
2433 }
2434 
2435 
2436 static int netlink_seq_show(struct seq_file *seq, void *v)
2437 {
2438         if (v == SEQ_START_TOKEN) {
2439                 seq_puts(seq,
2440                          "sk       Eth Pid    Groups   "
2441                          "Rmem     Wmem     Dump     Locks     Drops     Inode\n");
2442         } else {
2443                 struct sock *s = v;
2444                 struct netlink_sock *nlk = nlk_sk(s);
2445 
2446                 seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %d %-8d %-8d %-8lu\n",
2447                            s,
2448                            s->sk_protocol,
2449                            nlk->portid,
2450                            nlk->groups ? (u32)nlk->groups[0] : 0,
2451                            sk_rmem_alloc_get(s),
2452                            sk_wmem_alloc_get(s),
2453                            nlk->cb_running,
2454                            atomic_read(&s->sk_refcnt),
2455                            atomic_read(&s->sk_drops),
2456                            sock_i_ino(s)
2457                         );
2458 
2459         }
2460         return 0;
2461 }
2462 
2463 static const struct seq_operations netlink_seq_ops = {
2464         .start  = netlink_seq_start,
2465         .next   = netlink_seq_next,
2466         .stop   = netlink_seq_stop,
2467         .show   = netlink_seq_show,
2468 };
2469 
2470 
2471 static int netlink_seq_open(struct inode *inode, struct file *file)
2472 {
2473         return seq_open_net(inode, file, &netlink_seq_ops,
2474                                 sizeof(struct nl_seq_iter));
2475 }
2476 
2477 static const struct file_operations netlink_seq_fops = {
2478         .owner          = THIS_MODULE,
2479         .open           = netlink_seq_open,
2480         .read           = seq_read,
2481         .llseek         = seq_lseek,
2482         .release        = seq_release_net,
2483 };
2484 
2485 #endif
2486 
2487 int netlink_register_notifier(struct notifier_block *nb)
2488 {
2489         return atomic_notifier_chain_register(&netlink_chain, nb);
2490 }
2491 EXPORT_SYMBOL(netlink_register_notifier);
2492 
2493 int netlink_unregister_notifier(struct notifier_block *nb)
2494 {
2495         return atomic_notifier_chain_unregister(&netlink_chain, nb);
2496 }
2497 EXPORT_SYMBOL(netlink_unregister_notifier);
2498 
2499 static const struct proto_ops netlink_ops = {
2500         .family =       PF_NETLINK,
2501         .owner =        THIS_MODULE,
2502         .release =      netlink_release,
2503         .bind =         netlink_bind,
2504         .connect =      netlink_connect,
2505         .socketpair =   sock_no_socketpair,
2506         .accept =       sock_no_accept,
2507         .getname =      netlink_getname,
2508         .poll =         datagram_poll,
2509         .ioctl =        netlink_ioctl,
2510         .listen =       sock_no_listen,
2511         .shutdown =     sock_no_shutdown,
2512         .setsockopt =   netlink_setsockopt,
2513         .getsockopt =   netlink_getsockopt,
2514         .sendmsg =      netlink_sendmsg,
2515         .recvmsg =      netlink_recvmsg,
2516         .mmap =         sock_no_mmap,
2517         .sendpage =     sock_no_sendpage,
2518 };
2519 
2520 static const struct net_proto_family netlink_family_ops = {
2521         .family = PF_NETLINK,
2522         .create = netlink_create,
2523         .owner  = THIS_MODULE,  /* for consistency 8) */
2524 };
2525 
2526 static int __net_init netlink_net_init(struct net *net)
2527 {
2528 #ifdef CONFIG_PROC_FS
2529         if (!proc_create("netlink", 0, net->proc_net, &netlink_seq_fops))
2530                 return -ENOMEM;
2531 #endif
2532         return 0;
2533 }
2534 
2535 static void __net_exit netlink_net_exit(struct net *net)
2536 {
2537 #ifdef CONFIG_PROC_FS
2538         remove_proc_entry("netlink", net->proc_net);
2539 #endif
2540 }
2541 
2542 static void __init netlink_add_usersock_entry(void)
2543 {
2544         struct listeners *listeners;
2545         int groups = 32;
2546 
2547         listeners = kzalloc(sizeof(*listeners) + NLGRPSZ(groups), GFP_KERNEL);
2548         if (!listeners)
2549                 panic("netlink_add_usersock_entry: Cannot allocate listeners\n");
2550 
2551         netlink_table_grab();
2552 
2553         nl_table[NETLINK_USERSOCK].groups = groups;
2554         rcu_assign_pointer(nl_table[NETLINK_USERSOCK].listeners, listeners);
2555         nl_table[NETLINK_USERSOCK].module = THIS_MODULE;
2556         nl_table[NETLINK_USERSOCK].registered = 1;
2557         nl_table[NETLINK_USERSOCK].flags = NL_CFG_F_NONROOT_SEND;
2558 
2559         netlink_table_ungrab();
2560 }
2561 
2562 static struct pernet_operations __net_initdata netlink_net_ops = {
2563         .init = netlink_net_init,
2564         .exit = netlink_net_exit,
2565 };
2566 
2567 static inline u32 netlink_hash(const void *data, u32 len, u32 seed)
2568 {
2569         const struct netlink_sock *nlk = data;
2570         struct netlink_compare_arg arg;
2571 
2572         netlink_compare_arg_init(&arg, sock_net(&nlk->sk), nlk->portid);
2573         return jhash2((u32 *)&arg, netlink_compare_arg_len / sizeof(u32), seed);
2574 }
2575 
2576 static const struct rhashtable_params netlink_rhashtable_params = {
2577         .head_offset = offsetof(struct netlink_sock, node),
2578         .key_len = netlink_compare_arg_len,
2579         .obj_hashfn = netlink_hash,
2580         .obj_cmpfn = netlink_compare,
2581         .automatic_shrinking = true,
2582 };
2583 
2584 static int __init netlink_proto_init(void)
2585 {
2586         int i;
2587         int err = proto_register(&netlink_proto, 0);
2588 
2589         if (err != 0)
2590                 goto out;
2591 
2592         BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2593 
2594         nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
2595         if (!nl_table)
2596                 goto panic;
2597 
2598         for (i = 0; i < MAX_LINKS; i++) {
2599                 if (rhashtable_init(&nl_table[i].hash,
2600                                     &netlink_rhashtable_params) < 0) {
2601                         while (--i > 0)
2602                                 rhashtable_destroy(&nl_table[i].hash);
2603                         kfree(nl_table);
2604                         goto panic;
2605                 }
2606         }
2607 
2608         INIT_LIST_HEAD(&netlink_tap_all);
2609 
2610         netlink_add_usersock_entry();
2611 
2612         sock_register(&netlink_family_ops);
2613         register_pernet_subsys(&netlink_net_ops);
2614         /* The netlink device handler may be needed early. */
2615         rtnetlink_init();
2616 out:
2617         return err;
2618 panic:
2619         panic("netlink_init: Cannot allocate nl_table\n");
2620 }
2621 
2622 core_initcall(netlink_proto_init);
2623 

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