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[mirror_ubuntu-zesty-kernel.git] / net / netlink / af_netlink.c
1 /*
2 * NETLINK Kernel-user communication protocol.
3 *
4 * Authors: Alan Cox <alan@redhat.com>
5 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 *
12 * Tue Jun 26 14:36:48 MEST 2001 Herbert "herp" Rosmanith
13 * added netlink_proto_exit
14 * Tue Jan 22 18:32:44 BRST 2002 Arnaldo C. de Melo <acme@conectiva.com.br>
15 * use nlk_sk, as sk->protinfo is on a diet 8)
16 * Fri Jul 22 19:51:12 MEST 2005 Harald Welte <laforge@gnumonks.org>
17 * - inc module use count of module that owns
18 * the kernel socket in case userspace opens
19 * socket of same protocol
20 * - remove all module support, since netlink is
21 * mandatory if CONFIG_NET=y these days
22 */
23
24 #include <linux/module.h>
25
26 #include <linux/capability.h>
27 #include <linux/kernel.h>
28 #include <linux/init.h>
29 #include <linux/signal.h>
30 #include <linux/sched.h>
31 #include <linux/errno.h>
32 #include <linux/string.h>
33 #include <linux/stat.h>
34 #include <linux/socket.h>
35 #include <linux/un.h>
36 #include <linux/fcntl.h>
37 #include <linux/termios.h>
38 #include <linux/sockios.h>
39 #include <linux/net.h>
40 #include <linux/fs.h>
41 #include <linux/slab.h>
42 #include <asm/uaccess.h>
43 #include <linux/skbuff.h>
44 #include <linux/netdevice.h>
45 #include <linux/rtnetlink.h>
46 #include <linux/proc_fs.h>
47 #include <linux/seq_file.h>
48 #include <linux/notifier.h>
49 #include <linux/security.h>
50 #include <linux/jhash.h>
51 #include <linux/jiffies.h>
52 #include <linux/random.h>
53 #include <linux/bitops.h>
54 #include <linux/mm.h>
55 #include <linux/types.h>
56 #include <linux/audit.h>
57 #include <linux/selinux.h>
58 #include <linux/mutex.h>
59
60 #include <net/net_namespace.h>
61 #include <net/sock.h>
62 #include <net/scm.h>
63 #include <net/netlink.h>
64
65 #define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
66 #define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long))
67
68 struct netlink_sock {
69 /* struct sock has to be the first member of netlink_sock */
70 struct sock sk;
71 u32 pid;
72 u32 dst_pid;
73 u32 dst_group;
74 u32 flags;
75 u32 subscriptions;
76 u32 ngroups;
77 unsigned long *groups;
78 unsigned long state;
79 wait_queue_head_t wait;
80 struct netlink_callback *cb;
81 struct mutex *cb_mutex;
82 struct mutex cb_def_mutex;
83 void (*netlink_rcv)(struct sk_buff *skb);
84 struct module *module;
85 };
86
87 #define NETLINK_KERNEL_SOCKET 0x1
88 #define NETLINK_RECV_PKTINFO 0x2
89
90 static inline struct netlink_sock *nlk_sk(struct sock *sk)
91 {
92 return container_of(sk, struct netlink_sock, sk);
93 }
94
95 static inline int netlink_is_kernel(struct sock *sk)
96 {
97 return nlk_sk(sk)->flags & NETLINK_KERNEL_SOCKET;
98 }
99
100 struct nl_pid_hash {
101 struct hlist_head *table;
102 unsigned long rehash_time;
103
104 unsigned int mask;
105 unsigned int shift;
106
107 unsigned int entries;
108 unsigned int max_shift;
109
110 u32 rnd;
111 };
112
113 struct netlink_table {
114 struct nl_pid_hash hash;
115 struct hlist_head mc_list;
116 unsigned long *listeners;
117 unsigned int nl_nonroot;
118 unsigned int groups;
119 struct mutex *cb_mutex;
120 struct module *module;
121 int registered;
122 };
123
124 static struct netlink_table *nl_table;
125
126 static DECLARE_WAIT_QUEUE_HEAD(nl_table_wait);
127
128 static int netlink_dump(struct sock *sk);
129 static void netlink_destroy_callback(struct netlink_callback *cb);
130
131 static DEFINE_RWLOCK(nl_table_lock);
132 static atomic_t nl_table_users = ATOMIC_INIT(0);
133
134 static ATOMIC_NOTIFIER_HEAD(netlink_chain);
135
136 static u32 netlink_group_mask(u32 group)
137 {
138 return group ? 1 << (group - 1) : 0;
139 }
140
141 static struct hlist_head *nl_pid_hashfn(struct nl_pid_hash *hash, u32 pid)
142 {
143 return &hash->table[jhash_1word(pid, hash->rnd) & hash->mask];
144 }
145
146 static void netlink_sock_destruct(struct sock *sk)
147 {
148 struct netlink_sock *nlk = nlk_sk(sk);
149
150 if (nlk->cb) {
151 if (nlk->cb->done)
152 nlk->cb->done(nlk->cb);
153 netlink_destroy_callback(nlk->cb);
154 }
155
156 skb_queue_purge(&sk->sk_receive_queue);
157
158 if (!sock_flag(sk, SOCK_DEAD)) {
159 printk(KERN_ERR "Freeing alive netlink socket %p\n", sk);
160 return;
161 }
162 BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
163 BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
164 BUG_TRAP(!nlk_sk(sk)->groups);
165 }
166
167 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on
168 * SMP. Look, when several writers sleep and reader wakes them up, all but one
169 * immediately hit write lock and grab all the cpus. Exclusive sleep solves
170 * this, _but_ remember, it adds useless work on UP machines.
171 */
172
173 static void netlink_table_grab(void)
174 __acquires(nl_table_lock)
175 {
176 write_lock_irq(&nl_table_lock);
177
178 if (atomic_read(&nl_table_users)) {
179 DECLARE_WAITQUEUE(wait, current);
180
181 add_wait_queue_exclusive(&nl_table_wait, &wait);
182 for (;;) {
183 set_current_state(TASK_UNINTERRUPTIBLE);
184 if (atomic_read(&nl_table_users) == 0)
185 break;
186 write_unlock_irq(&nl_table_lock);
187 schedule();
188 write_lock_irq(&nl_table_lock);
189 }
190
191 __set_current_state(TASK_RUNNING);
192 remove_wait_queue(&nl_table_wait, &wait);
193 }
194 }
195
196 static void netlink_table_ungrab(void)
197 __releases(nl_table_lock)
198 {
199 write_unlock_irq(&nl_table_lock);
200 wake_up(&nl_table_wait);
201 }
202
203 static inline void
204 netlink_lock_table(void)
205 {
206 /* read_lock() synchronizes us to netlink_table_grab */
207
208 read_lock(&nl_table_lock);
209 atomic_inc(&nl_table_users);
210 read_unlock(&nl_table_lock);
211 }
212
213 static inline void
214 netlink_unlock_table(void)
215 {
216 if (atomic_dec_and_test(&nl_table_users))
217 wake_up(&nl_table_wait);
218 }
219
220 static inline struct sock *netlink_lookup(struct net *net, int protocol,
221 u32 pid)
222 {
223 struct nl_pid_hash *hash = &nl_table[protocol].hash;
224 struct hlist_head *head;
225 struct sock *sk;
226 struct hlist_node *node;
227
228 read_lock(&nl_table_lock);
229 head = nl_pid_hashfn(hash, pid);
230 sk_for_each(sk, node, head) {
231 if ((sk->sk_net == net) && (nlk_sk(sk)->pid == pid)) {
232 sock_hold(sk);
233 goto found;
234 }
235 }
236 sk = NULL;
237 found:
238 read_unlock(&nl_table_lock);
239 return sk;
240 }
241
242 static inline struct hlist_head *nl_pid_hash_zalloc(size_t size)
243 {
244 if (size <= PAGE_SIZE)
245 return kzalloc(size, GFP_ATOMIC);
246 else
247 return (struct hlist_head *)
248 __get_free_pages(GFP_ATOMIC | __GFP_ZERO,
249 get_order(size));
250 }
251
252 static inline void nl_pid_hash_free(struct hlist_head *table, size_t size)
253 {
254 if (size <= PAGE_SIZE)
255 kfree(table);
256 else
257 free_pages((unsigned long)table, get_order(size));
258 }
259
260 static int nl_pid_hash_rehash(struct nl_pid_hash *hash, int grow)
261 {
262 unsigned int omask, mask, shift;
263 size_t osize, size;
264 struct hlist_head *otable, *table;
265 int i;
266
267 omask = mask = hash->mask;
268 osize = size = (mask + 1) * sizeof(*table);
269 shift = hash->shift;
270
271 if (grow) {
272 if (++shift > hash->max_shift)
273 return 0;
274 mask = mask * 2 + 1;
275 size *= 2;
276 }
277
278 table = nl_pid_hash_zalloc(size);
279 if (!table)
280 return 0;
281
282 otable = hash->table;
283 hash->table = table;
284 hash->mask = mask;
285 hash->shift = shift;
286 get_random_bytes(&hash->rnd, sizeof(hash->rnd));
287
288 for (i = 0; i <= omask; i++) {
289 struct sock *sk;
290 struct hlist_node *node, *tmp;
291
292 sk_for_each_safe(sk, node, tmp, &otable[i])
293 __sk_add_node(sk, nl_pid_hashfn(hash, nlk_sk(sk)->pid));
294 }
295
296 nl_pid_hash_free(otable, osize);
297 hash->rehash_time = jiffies + 10 * 60 * HZ;
298 return 1;
299 }
300
301 static inline int nl_pid_hash_dilute(struct nl_pid_hash *hash, int len)
302 {
303 int avg = hash->entries >> hash->shift;
304
305 if (unlikely(avg > 1) && nl_pid_hash_rehash(hash, 1))
306 return 1;
307
308 if (unlikely(len > avg) && time_after(jiffies, hash->rehash_time)) {
309 nl_pid_hash_rehash(hash, 0);
310 return 1;
311 }
312
313 return 0;
314 }
315
316 static const struct proto_ops netlink_ops;
317
318 static void
319 netlink_update_listeners(struct sock *sk)
320 {
321 struct netlink_table *tbl = &nl_table[sk->sk_protocol];
322 struct hlist_node *node;
323 unsigned long mask;
324 unsigned int i;
325
326 for (i = 0; i < NLGRPLONGS(tbl->groups); i++) {
327 mask = 0;
328 sk_for_each_bound(sk, node, &tbl->mc_list) {
329 if (i < NLGRPLONGS(nlk_sk(sk)->ngroups))
330 mask |= nlk_sk(sk)->groups[i];
331 }
332 tbl->listeners[i] = mask;
333 }
334 /* this function is only called with the netlink table "grabbed", which
335 * makes sure updates are visible before bind or setsockopt return. */
336 }
337
338 static int netlink_insert(struct sock *sk, struct net *net, u32 pid)
339 {
340 struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
341 struct hlist_head *head;
342 int err = -EADDRINUSE;
343 struct sock *osk;
344 struct hlist_node *node;
345 int len;
346
347 netlink_table_grab();
348 head = nl_pid_hashfn(hash, pid);
349 len = 0;
350 sk_for_each(osk, node, head) {
351 if ((osk->sk_net == net) && (nlk_sk(osk)->pid == pid))
352 break;
353 len++;
354 }
355 if (node)
356 goto err;
357
358 err = -EBUSY;
359 if (nlk_sk(sk)->pid)
360 goto err;
361
362 err = -ENOMEM;
363 if (BITS_PER_LONG > 32 && unlikely(hash->entries >= UINT_MAX))
364 goto err;
365
366 if (len && nl_pid_hash_dilute(hash, len))
367 head = nl_pid_hashfn(hash, pid);
368 hash->entries++;
369 nlk_sk(sk)->pid = pid;
370 sk_add_node(sk, head);
371 err = 0;
372
373 err:
374 netlink_table_ungrab();
375 return err;
376 }
377
378 static void netlink_remove(struct sock *sk)
379 {
380 netlink_table_grab();
381 if (sk_del_node_init(sk))
382 nl_table[sk->sk_protocol].hash.entries--;
383 if (nlk_sk(sk)->subscriptions)
384 __sk_del_bind_node(sk);
385 netlink_table_ungrab();
386 }
387
388 static struct proto netlink_proto = {
389 .name = "NETLINK",
390 .owner = THIS_MODULE,
391 .obj_size = sizeof(struct netlink_sock),
392 };
393
394 static int __netlink_create(struct net *net, struct socket *sock,
395 struct mutex *cb_mutex, int protocol)
396 {
397 struct sock *sk;
398 struct netlink_sock *nlk;
399
400 sock->ops = &netlink_ops;
401
402 sk = sk_alloc(net, PF_NETLINK, GFP_KERNEL, &netlink_proto);
403 if (!sk)
404 return -ENOMEM;
405
406 sock_init_data(sock, sk);
407
408 nlk = nlk_sk(sk);
409 if (cb_mutex)
410 nlk->cb_mutex = cb_mutex;
411 else {
412 nlk->cb_mutex = &nlk->cb_def_mutex;
413 mutex_init(nlk->cb_mutex);
414 }
415 init_waitqueue_head(&nlk->wait);
416
417 sk->sk_destruct = netlink_sock_destruct;
418 sk->sk_protocol = protocol;
419 return 0;
420 }
421
422 static int netlink_create(struct net *net, struct socket *sock, int protocol)
423 {
424 struct module *module = NULL;
425 struct mutex *cb_mutex;
426 struct netlink_sock *nlk;
427 int err = 0;
428
429 sock->state = SS_UNCONNECTED;
430
431 if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
432 return -ESOCKTNOSUPPORT;
433
434 if (protocol < 0 || protocol >= MAX_LINKS)
435 return -EPROTONOSUPPORT;
436
437 netlink_lock_table();
438 #ifdef CONFIG_KMOD
439 if (!nl_table[protocol].registered) {
440 netlink_unlock_table();
441 request_module("net-pf-%d-proto-%d", PF_NETLINK, protocol);
442 netlink_lock_table();
443 }
444 #endif
445 if (nl_table[protocol].registered &&
446 try_module_get(nl_table[protocol].module))
447 module = nl_table[protocol].module;
448 cb_mutex = nl_table[protocol].cb_mutex;
449 netlink_unlock_table();
450
451 err = __netlink_create(net, sock, cb_mutex, protocol);
452 if (err < 0)
453 goto out_module;
454
455 nlk = nlk_sk(sock->sk);
456 nlk->module = module;
457 out:
458 return err;
459
460 out_module:
461 module_put(module);
462 goto out;
463 }
464
465 static int netlink_release(struct socket *sock)
466 {
467 struct sock *sk = sock->sk;
468 struct netlink_sock *nlk;
469
470 if (!sk)
471 return 0;
472
473 netlink_remove(sk);
474 sock_orphan(sk);
475 nlk = nlk_sk(sk);
476
477 /*
478 * OK. Socket is unlinked, any packets that arrive now
479 * will be purged.
480 */
481
482 sock->sk = NULL;
483 wake_up_interruptible_all(&nlk->wait);
484
485 skb_queue_purge(&sk->sk_write_queue);
486
487 if (nlk->pid && !nlk->subscriptions) {
488 struct netlink_notify n = {
489 .net = sk->sk_net,
490 .protocol = sk->sk_protocol,
491 .pid = nlk->pid,
492 };
493 atomic_notifier_call_chain(&netlink_chain,
494 NETLINK_URELEASE, &n);
495 }
496
497 module_put(nlk->module);
498
499 netlink_table_grab();
500 if (netlink_is_kernel(sk)) {
501 kfree(nl_table[sk->sk_protocol].listeners);
502 nl_table[sk->sk_protocol].module = NULL;
503 nl_table[sk->sk_protocol].registered = 0;
504 } else if (nlk->subscriptions)
505 netlink_update_listeners(sk);
506 netlink_table_ungrab();
507
508 kfree(nlk->groups);
509 nlk->groups = NULL;
510
511 sock_put(sk);
512 return 0;
513 }
514
515 static int netlink_autobind(struct socket *sock)
516 {
517 struct sock *sk = sock->sk;
518 struct net *net = sk->sk_net;
519 struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
520 struct hlist_head *head;
521 struct sock *osk;
522 struct hlist_node *node;
523 s32 pid = current->tgid;
524 int err;
525 static s32 rover = -4097;
526
527 retry:
528 cond_resched();
529 netlink_table_grab();
530 head = nl_pid_hashfn(hash, pid);
531 sk_for_each(osk, node, head) {
532 if ((osk->sk_net != net))
533 continue;
534 if (nlk_sk(osk)->pid == pid) {
535 /* Bind collision, search negative pid values. */
536 pid = rover--;
537 if (rover > -4097)
538 rover = -4097;
539 netlink_table_ungrab();
540 goto retry;
541 }
542 }
543 netlink_table_ungrab();
544
545 err = netlink_insert(sk, net, pid);
546 if (err == -EADDRINUSE)
547 goto retry;
548
549 /* If 2 threads race to autobind, that is fine. */
550 if (err == -EBUSY)
551 err = 0;
552
553 return err;
554 }
555
556 static inline int netlink_capable(struct socket *sock, unsigned int flag)
557 {
558 return (nl_table[sock->sk->sk_protocol].nl_nonroot & flag) ||
559 capable(CAP_NET_ADMIN);
560 }
561
562 static void
563 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
564 {
565 struct netlink_sock *nlk = nlk_sk(sk);
566
567 if (nlk->subscriptions && !subscriptions)
568 __sk_del_bind_node(sk);
569 else if (!nlk->subscriptions && subscriptions)
570 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
571 nlk->subscriptions = subscriptions;
572 }
573
574 static int netlink_realloc_groups(struct sock *sk)
575 {
576 struct netlink_sock *nlk = nlk_sk(sk);
577 unsigned int groups;
578 unsigned long *new_groups;
579 int err = 0;
580
581 netlink_table_grab();
582
583 groups = nl_table[sk->sk_protocol].groups;
584 if (!nl_table[sk->sk_protocol].registered) {
585 err = -ENOENT;
586 goto out_unlock;
587 }
588
589 if (nlk->ngroups >= groups)
590 goto out_unlock;
591
592 new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
593 if (new_groups == NULL) {
594 err = -ENOMEM;
595 goto out_unlock;
596 }
597 memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
598 NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
599
600 nlk->groups = new_groups;
601 nlk->ngroups = groups;
602 out_unlock:
603 netlink_table_ungrab();
604 return err;
605 }
606
607 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
608 int addr_len)
609 {
610 struct sock *sk = sock->sk;
611 struct net *net = sk->sk_net;
612 struct netlink_sock *nlk = nlk_sk(sk);
613 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
614 int err;
615
616 if (nladdr->nl_family != AF_NETLINK)
617 return -EINVAL;
618
619 /* Only superuser is allowed to listen multicasts */
620 if (nladdr->nl_groups) {
621 if (!netlink_capable(sock, NL_NONROOT_RECV))
622 return -EPERM;
623 err = netlink_realloc_groups(sk);
624 if (err)
625 return err;
626 }
627
628 if (nlk->pid) {
629 if (nladdr->nl_pid != nlk->pid)
630 return -EINVAL;
631 } else {
632 err = nladdr->nl_pid ?
633 netlink_insert(sk, net, nladdr->nl_pid) :
634 netlink_autobind(sock);
635 if (err)
636 return err;
637 }
638
639 if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
640 return 0;
641
642 netlink_table_grab();
643 netlink_update_subscriptions(sk, nlk->subscriptions +
644 hweight32(nladdr->nl_groups) -
645 hweight32(nlk->groups[0]));
646 nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
647 netlink_update_listeners(sk);
648 netlink_table_ungrab();
649
650 return 0;
651 }
652
653 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
654 int alen, int flags)
655 {
656 int err = 0;
657 struct sock *sk = sock->sk;
658 struct netlink_sock *nlk = nlk_sk(sk);
659 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
660
661 if (addr->sa_family == AF_UNSPEC) {
662 sk->sk_state = NETLINK_UNCONNECTED;
663 nlk->dst_pid = 0;
664 nlk->dst_group = 0;
665 return 0;
666 }
667 if (addr->sa_family != AF_NETLINK)
668 return -EINVAL;
669
670 /* Only superuser is allowed to send multicasts */
671 if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND))
672 return -EPERM;
673
674 if (!nlk->pid)
675 err = netlink_autobind(sock);
676
677 if (err == 0) {
678 sk->sk_state = NETLINK_CONNECTED;
679 nlk->dst_pid = nladdr->nl_pid;
680 nlk->dst_group = ffs(nladdr->nl_groups);
681 }
682
683 return err;
684 }
685
686 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
687 int *addr_len, int peer)
688 {
689 struct sock *sk = sock->sk;
690 struct netlink_sock *nlk = nlk_sk(sk);
691 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
692
693 nladdr->nl_family = AF_NETLINK;
694 nladdr->nl_pad = 0;
695 *addr_len = sizeof(*nladdr);
696
697 if (peer) {
698 nladdr->nl_pid = nlk->dst_pid;
699 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
700 } else {
701 nladdr->nl_pid = nlk->pid;
702 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
703 }
704 return 0;
705 }
706
707 static void netlink_overrun(struct sock *sk)
708 {
709 if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
710 sk->sk_err = ENOBUFS;
711 sk->sk_error_report(sk);
712 }
713 }
714
715 static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid)
716 {
717 struct sock *sock;
718 struct netlink_sock *nlk;
719
720 sock = netlink_lookup(ssk->sk_net, ssk->sk_protocol, pid);
721 if (!sock)
722 return ERR_PTR(-ECONNREFUSED);
723
724 /* Don't bother queuing skb if kernel socket has no input function */
725 nlk = nlk_sk(sock);
726 if (sock->sk_state == NETLINK_CONNECTED &&
727 nlk->dst_pid != nlk_sk(ssk)->pid) {
728 sock_put(sock);
729 return ERR_PTR(-ECONNREFUSED);
730 }
731 return sock;
732 }
733
734 struct sock *netlink_getsockbyfilp(struct file *filp)
735 {
736 struct inode *inode = filp->f_path.dentry->d_inode;
737 struct sock *sock;
738
739 if (!S_ISSOCK(inode->i_mode))
740 return ERR_PTR(-ENOTSOCK);
741
742 sock = SOCKET_I(inode)->sk;
743 if (sock->sk_family != AF_NETLINK)
744 return ERR_PTR(-EINVAL);
745
746 sock_hold(sock);
747 return sock;
748 }
749
750 /*
751 * Attach a skb to a netlink socket.
752 * The caller must hold a reference to the destination socket. On error, the
753 * reference is dropped. The skb is not send to the destination, just all
754 * all error checks are performed and memory in the queue is reserved.
755 * Return values:
756 * < 0: error. skb freed, reference to sock dropped.
757 * 0: continue
758 * 1: repeat lookup - reference dropped while waiting for socket memory.
759 */
760 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, int nonblock,
761 long *timeo, struct sock *ssk)
762 {
763 struct netlink_sock *nlk;
764
765 nlk = nlk_sk(sk);
766
767 if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
768 test_bit(0, &nlk->state)) {
769 DECLARE_WAITQUEUE(wait, current);
770 if (!*timeo) {
771 if (!ssk || netlink_is_kernel(ssk))
772 netlink_overrun(sk);
773 sock_put(sk);
774 kfree_skb(skb);
775 return -EAGAIN;
776 }
777
778 __set_current_state(TASK_INTERRUPTIBLE);
779 add_wait_queue(&nlk->wait, &wait);
780
781 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
782 test_bit(0, &nlk->state)) &&
783 !sock_flag(sk, SOCK_DEAD))
784 *timeo = schedule_timeout(*timeo);
785
786 __set_current_state(TASK_RUNNING);
787 remove_wait_queue(&nlk->wait, &wait);
788 sock_put(sk);
789
790 if (signal_pending(current)) {
791 kfree_skb(skb);
792 return sock_intr_errno(*timeo);
793 }
794 return 1;
795 }
796 skb_set_owner_r(skb, sk);
797 return 0;
798 }
799
800 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
801 {
802 int len = skb->len;
803
804 skb_queue_tail(&sk->sk_receive_queue, skb);
805 sk->sk_data_ready(sk, len);
806 sock_put(sk);
807 return len;
808 }
809
810 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
811 {
812 kfree_skb(skb);
813 sock_put(sk);
814 }
815
816 static inline struct sk_buff *netlink_trim(struct sk_buff *skb,
817 gfp_t allocation)
818 {
819 int delta;
820
821 skb_orphan(skb);
822
823 delta = skb->end - skb->tail;
824 if (delta * 2 < skb->truesize)
825 return skb;
826
827 if (skb_shared(skb)) {
828 struct sk_buff *nskb = skb_clone(skb, allocation);
829 if (!nskb)
830 return skb;
831 kfree_skb(skb);
832 skb = nskb;
833 }
834
835 if (!pskb_expand_head(skb, 0, -delta, allocation))
836 skb->truesize -= delta;
837
838 return skb;
839 }
840
841 static inline void netlink_rcv_wake(struct sock *sk)
842 {
843 struct netlink_sock *nlk = nlk_sk(sk);
844
845 if (skb_queue_empty(&sk->sk_receive_queue))
846 clear_bit(0, &nlk->state);
847 if (!test_bit(0, &nlk->state))
848 wake_up_interruptible(&nlk->wait);
849 }
850
851 static inline int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb)
852 {
853 int ret;
854 struct netlink_sock *nlk = nlk_sk(sk);
855
856 ret = -ECONNREFUSED;
857 if (nlk->netlink_rcv != NULL) {
858 ret = skb->len;
859 skb_set_owner_r(skb, sk);
860 nlk->netlink_rcv(skb);
861 }
862 kfree_skb(skb);
863 sock_put(sk);
864 return ret;
865 }
866
867 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
868 u32 pid, int nonblock)
869 {
870 struct sock *sk;
871 int err;
872 long timeo;
873
874 skb = netlink_trim(skb, gfp_any());
875
876 timeo = sock_sndtimeo(ssk, nonblock);
877 retry:
878 sk = netlink_getsockbypid(ssk, pid);
879 if (IS_ERR(sk)) {
880 kfree_skb(skb);
881 return PTR_ERR(sk);
882 }
883 if (netlink_is_kernel(sk))
884 return netlink_unicast_kernel(sk, skb);
885
886 err = netlink_attachskb(sk, skb, nonblock, &timeo, ssk);
887 if (err == 1)
888 goto retry;
889 if (err)
890 return err;
891
892 return netlink_sendskb(sk, skb);
893 }
894 EXPORT_SYMBOL(netlink_unicast);
895
896 int netlink_has_listeners(struct sock *sk, unsigned int group)
897 {
898 int res = 0;
899 unsigned long *listeners;
900
901 BUG_ON(!netlink_is_kernel(sk));
902
903 rcu_read_lock();
904 listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
905
906 if (group - 1 < nl_table[sk->sk_protocol].groups)
907 res = test_bit(group - 1, listeners);
908
909 rcu_read_unlock();
910
911 return res;
912 }
913 EXPORT_SYMBOL_GPL(netlink_has_listeners);
914
915 static inline int netlink_broadcast_deliver(struct sock *sk,
916 struct sk_buff *skb)
917 {
918 struct netlink_sock *nlk = nlk_sk(sk);
919
920 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
921 !test_bit(0, &nlk->state)) {
922 skb_set_owner_r(skb, sk);
923 skb_queue_tail(&sk->sk_receive_queue, skb);
924 sk->sk_data_ready(sk, skb->len);
925 return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf;
926 }
927 return -1;
928 }
929
930 struct netlink_broadcast_data {
931 struct sock *exclude_sk;
932 struct net *net;
933 u32 pid;
934 u32 group;
935 int failure;
936 int congested;
937 int delivered;
938 gfp_t allocation;
939 struct sk_buff *skb, *skb2;
940 };
941
942 static inline int do_one_broadcast(struct sock *sk,
943 struct netlink_broadcast_data *p)
944 {
945 struct netlink_sock *nlk = nlk_sk(sk);
946 int val;
947
948 if (p->exclude_sk == sk)
949 goto out;
950
951 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
952 !test_bit(p->group - 1, nlk->groups))
953 goto out;
954
955 if ((sk->sk_net != p->net))
956 goto out;
957
958 if (p->failure) {
959 netlink_overrun(sk);
960 goto out;
961 }
962
963 sock_hold(sk);
964 if (p->skb2 == NULL) {
965 if (skb_shared(p->skb)) {
966 p->skb2 = skb_clone(p->skb, p->allocation);
967 } else {
968 p->skb2 = skb_get(p->skb);
969 /*
970 * skb ownership may have been set when
971 * delivered to a previous socket.
972 */
973 skb_orphan(p->skb2);
974 }
975 }
976 if (p->skb2 == NULL) {
977 netlink_overrun(sk);
978 /* Clone failed. Notify ALL listeners. */
979 p->failure = 1;
980 } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
981 netlink_overrun(sk);
982 } else {
983 p->congested |= val;
984 p->delivered = 1;
985 p->skb2 = NULL;
986 }
987 sock_put(sk);
988
989 out:
990 return 0;
991 }
992
993 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid,
994 u32 group, gfp_t allocation)
995 {
996 struct net *net = ssk->sk_net;
997 struct netlink_broadcast_data info;
998 struct hlist_node *node;
999 struct sock *sk;
1000
1001 skb = netlink_trim(skb, allocation);
1002
1003 info.exclude_sk = ssk;
1004 info.net = net;
1005 info.pid = pid;
1006 info.group = group;
1007 info.failure = 0;
1008 info.congested = 0;
1009 info.delivered = 0;
1010 info.allocation = allocation;
1011 info.skb = skb;
1012 info.skb2 = NULL;
1013
1014 /* While we sleep in clone, do not allow to change socket list */
1015
1016 netlink_lock_table();
1017
1018 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1019 do_one_broadcast(sk, &info);
1020
1021 kfree_skb(skb);
1022
1023 netlink_unlock_table();
1024
1025 if (info.skb2)
1026 kfree_skb(info.skb2);
1027
1028 if (info.delivered) {
1029 if (info.congested && (allocation & __GFP_WAIT))
1030 yield();
1031 return 0;
1032 }
1033 if (info.failure)
1034 return -ENOBUFS;
1035 return -ESRCH;
1036 }
1037 EXPORT_SYMBOL(netlink_broadcast);
1038
1039 struct netlink_set_err_data {
1040 struct sock *exclude_sk;
1041 u32 pid;
1042 u32 group;
1043 int code;
1044 };
1045
1046 static inline int do_one_set_err(struct sock *sk,
1047 struct netlink_set_err_data *p)
1048 {
1049 struct netlink_sock *nlk = nlk_sk(sk);
1050
1051 if (sk == p->exclude_sk)
1052 goto out;
1053
1054 if (sk->sk_net != p->exclude_sk->sk_net)
1055 goto out;
1056
1057 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
1058 !test_bit(p->group - 1, nlk->groups))
1059 goto out;
1060
1061 sk->sk_err = p->code;
1062 sk->sk_error_report(sk);
1063 out:
1064 return 0;
1065 }
1066
1067 void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
1068 {
1069 struct netlink_set_err_data info;
1070 struct hlist_node *node;
1071 struct sock *sk;
1072
1073 info.exclude_sk = ssk;
1074 info.pid = pid;
1075 info.group = group;
1076 info.code = code;
1077
1078 read_lock(&nl_table_lock);
1079
1080 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1081 do_one_set_err(sk, &info);
1082
1083 read_unlock(&nl_table_lock);
1084 }
1085
1086 /* must be called with netlink table grabbed */
1087 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1088 unsigned int group,
1089 int is_new)
1090 {
1091 int old, new = !!is_new, subscriptions;
1092
1093 old = test_bit(group - 1, nlk->groups);
1094 subscriptions = nlk->subscriptions - old + new;
1095 if (new)
1096 __set_bit(group - 1, nlk->groups);
1097 else
1098 __clear_bit(group - 1, nlk->groups);
1099 netlink_update_subscriptions(&nlk->sk, subscriptions);
1100 netlink_update_listeners(&nlk->sk);
1101 }
1102
1103 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1104 char __user *optval, int optlen)
1105 {
1106 struct sock *sk = sock->sk;
1107 struct netlink_sock *nlk = nlk_sk(sk);
1108 unsigned int val = 0;
1109 int err;
1110
1111 if (level != SOL_NETLINK)
1112 return -ENOPROTOOPT;
1113
1114 if (optlen >= sizeof(int) &&
1115 get_user(val, (unsigned int __user *)optval))
1116 return -EFAULT;
1117
1118 switch (optname) {
1119 case NETLINK_PKTINFO:
1120 if (val)
1121 nlk->flags |= NETLINK_RECV_PKTINFO;
1122 else
1123 nlk->flags &= ~NETLINK_RECV_PKTINFO;
1124 err = 0;
1125 break;
1126 case NETLINK_ADD_MEMBERSHIP:
1127 case NETLINK_DROP_MEMBERSHIP: {
1128 if (!netlink_capable(sock, NL_NONROOT_RECV))
1129 return -EPERM;
1130 err = netlink_realloc_groups(sk);
1131 if (err)
1132 return err;
1133 if (!val || val - 1 >= nlk->ngroups)
1134 return -EINVAL;
1135 netlink_table_grab();
1136 netlink_update_socket_mc(nlk, val,
1137 optname == NETLINK_ADD_MEMBERSHIP);
1138 netlink_table_ungrab();
1139 err = 0;
1140 break;
1141 }
1142 default:
1143 err = -ENOPROTOOPT;
1144 }
1145 return err;
1146 }
1147
1148 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1149 char __user *optval, int __user *optlen)
1150 {
1151 struct sock *sk = sock->sk;
1152 struct netlink_sock *nlk = nlk_sk(sk);
1153 int len, val, err;
1154
1155 if (level != SOL_NETLINK)
1156 return -ENOPROTOOPT;
1157
1158 if (get_user(len, optlen))
1159 return -EFAULT;
1160 if (len < 0)
1161 return -EINVAL;
1162
1163 switch (optname) {
1164 case NETLINK_PKTINFO:
1165 if (len < sizeof(int))
1166 return -EINVAL;
1167 len = sizeof(int);
1168 val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
1169 if (put_user(len, optlen) ||
1170 put_user(val, optval))
1171 return -EFAULT;
1172 err = 0;
1173 break;
1174 default:
1175 err = -ENOPROTOOPT;
1176 }
1177 return err;
1178 }
1179
1180 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1181 {
1182 struct nl_pktinfo info;
1183
1184 info.group = NETLINK_CB(skb).dst_group;
1185 put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1186 }
1187
1188 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
1189 struct msghdr *msg, size_t len)
1190 {
1191 struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1192 struct sock *sk = sock->sk;
1193 struct netlink_sock *nlk = nlk_sk(sk);
1194 struct sockaddr_nl *addr = msg->msg_name;
1195 u32 dst_pid;
1196 u32 dst_group;
1197 struct sk_buff *skb;
1198 int err;
1199 struct scm_cookie scm;
1200
1201 if (msg->msg_flags&MSG_OOB)
1202 return -EOPNOTSUPP;
1203
1204 if (NULL == siocb->scm)
1205 siocb->scm = &scm;
1206 err = scm_send(sock, msg, siocb->scm);
1207 if (err < 0)
1208 return err;
1209
1210 if (msg->msg_namelen) {
1211 if (addr->nl_family != AF_NETLINK)
1212 return -EINVAL;
1213 dst_pid = addr->nl_pid;
1214 dst_group = ffs(addr->nl_groups);
1215 if (dst_group && !netlink_capable(sock, NL_NONROOT_SEND))
1216 return -EPERM;
1217 } else {
1218 dst_pid = nlk->dst_pid;
1219 dst_group = nlk->dst_group;
1220 }
1221
1222 if (!nlk->pid) {
1223 err = netlink_autobind(sock);
1224 if (err)
1225 goto out;
1226 }
1227
1228 err = -EMSGSIZE;
1229 if (len > sk->sk_sndbuf - 32)
1230 goto out;
1231 err = -ENOBUFS;
1232 skb = alloc_skb(len, GFP_KERNEL);
1233 if (skb == NULL)
1234 goto out;
1235
1236 NETLINK_CB(skb).pid = nlk->pid;
1237 NETLINK_CB(skb).dst_group = dst_group;
1238 NETLINK_CB(skb).loginuid = audit_get_loginuid(current->audit_context);
1239 selinux_get_task_sid(current, &(NETLINK_CB(skb).sid));
1240 memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
1241
1242 /* What can I do? Netlink is asynchronous, so that
1243 we will have to save current capabilities to
1244 check them, when this message will be delivered
1245 to corresponding kernel module. --ANK (980802)
1246 */
1247
1248 err = -EFAULT;
1249 if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
1250 kfree_skb(skb);
1251 goto out;
1252 }
1253
1254 err = security_netlink_send(sk, skb);
1255 if (err) {
1256 kfree_skb(skb);
1257 goto out;
1258 }
1259
1260 if (dst_group) {
1261 atomic_inc(&skb->users);
1262 netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL);
1263 }
1264 err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT);
1265
1266 out:
1267 return err;
1268 }
1269
1270 static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
1271 struct msghdr *msg, size_t len,
1272 int flags)
1273 {
1274 struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1275 struct scm_cookie scm;
1276 struct sock *sk = sock->sk;
1277 struct netlink_sock *nlk = nlk_sk(sk);
1278 int noblock = flags&MSG_DONTWAIT;
1279 size_t copied;
1280 struct sk_buff *skb;
1281 int err;
1282
1283 if (flags&MSG_OOB)
1284 return -EOPNOTSUPP;
1285
1286 copied = 0;
1287
1288 skb = skb_recv_datagram(sk, flags, noblock, &err);
1289 if (skb == NULL)
1290 goto out;
1291
1292 msg->msg_namelen = 0;
1293
1294 copied = skb->len;
1295 if (len < copied) {
1296 msg->msg_flags |= MSG_TRUNC;
1297 copied = len;
1298 }
1299
1300 skb_reset_transport_header(skb);
1301 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
1302
1303 if (msg->msg_name) {
1304 struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name;
1305 addr->nl_family = AF_NETLINK;
1306 addr->nl_pad = 0;
1307 addr->nl_pid = NETLINK_CB(skb).pid;
1308 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1309 msg->msg_namelen = sizeof(*addr);
1310 }
1311
1312 if (nlk->flags & NETLINK_RECV_PKTINFO)
1313 netlink_cmsg_recv_pktinfo(msg, skb);
1314
1315 if (NULL == siocb->scm) {
1316 memset(&scm, 0, sizeof(scm));
1317 siocb->scm = &scm;
1318 }
1319 siocb->scm->creds = *NETLINK_CREDS(skb);
1320 if (flags & MSG_TRUNC)
1321 copied = skb->len;
1322 skb_free_datagram(sk, skb);
1323
1324 if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2)
1325 netlink_dump(sk);
1326
1327 scm_recv(sock, msg, siocb->scm, flags);
1328 out:
1329 netlink_rcv_wake(sk);
1330 return err ? : copied;
1331 }
1332
1333 static void netlink_data_ready(struct sock *sk, int len)
1334 {
1335 BUG();
1336 }
1337
1338 /*
1339 * We export these functions to other modules. They provide a
1340 * complete set of kernel non-blocking support for message
1341 * queueing.
1342 */
1343
1344 struct sock *
1345 netlink_kernel_create(struct net *net, int unit, unsigned int groups,
1346 void (*input)(struct sk_buff *skb),
1347 struct mutex *cb_mutex, struct module *module)
1348 {
1349 struct socket *sock;
1350 struct sock *sk;
1351 struct netlink_sock *nlk;
1352 unsigned long *listeners = NULL;
1353
1354 BUG_ON(!nl_table);
1355
1356 if (unit < 0 || unit >= MAX_LINKS)
1357 return NULL;
1358
1359 if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
1360 return NULL;
1361
1362 if (__netlink_create(net, sock, cb_mutex, unit) < 0)
1363 goto out_sock_release;
1364
1365 if (groups < 32)
1366 groups = 32;
1367
1368 listeners = kzalloc(NLGRPSZ(groups), GFP_KERNEL);
1369 if (!listeners)
1370 goto out_sock_release;
1371
1372 sk = sock->sk;
1373 sk->sk_data_ready = netlink_data_ready;
1374 if (input)
1375 nlk_sk(sk)->netlink_rcv = input;
1376
1377 if (netlink_insert(sk, net, 0))
1378 goto out_sock_release;
1379
1380 nlk = nlk_sk(sk);
1381 nlk->flags |= NETLINK_KERNEL_SOCKET;
1382
1383 netlink_table_grab();
1384 if (!nl_table[unit].registered) {
1385 nl_table[unit].groups = groups;
1386 nl_table[unit].listeners = listeners;
1387 nl_table[unit].cb_mutex = cb_mutex;
1388 nl_table[unit].module = module;
1389 nl_table[unit].registered = 1;
1390 } else {
1391 kfree(listeners);
1392 }
1393 netlink_table_ungrab();
1394
1395 return sk;
1396
1397 out_sock_release:
1398 kfree(listeners);
1399 sock_release(sock);
1400 return NULL;
1401 }
1402 EXPORT_SYMBOL(netlink_kernel_create);
1403
1404 /**
1405 * netlink_change_ngroups - change number of multicast groups
1406 *
1407 * This changes the number of multicast groups that are available
1408 * on a certain netlink family. Note that it is not possible to
1409 * change the number of groups to below 32. Also note that it does
1410 * not implicitly call netlink_clear_multicast_users() when the
1411 * number of groups is reduced.
1412 *
1413 * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
1414 * @groups: The new number of groups.
1415 */
1416 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
1417 {
1418 unsigned long *listeners, *old = NULL;
1419 struct netlink_table *tbl = &nl_table[sk->sk_protocol];
1420 int err = 0;
1421
1422 if (groups < 32)
1423 groups = 32;
1424
1425 netlink_table_grab();
1426 if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
1427 listeners = kzalloc(NLGRPSZ(groups), GFP_ATOMIC);
1428 if (!listeners) {
1429 err = -ENOMEM;
1430 goto out_ungrab;
1431 }
1432 old = tbl->listeners;
1433 memcpy(listeners, old, NLGRPSZ(tbl->groups));
1434 rcu_assign_pointer(tbl->listeners, listeners);
1435 }
1436 tbl->groups = groups;
1437
1438 out_ungrab:
1439 netlink_table_ungrab();
1440 synchronize_rcu();
1441 kfree(old);
1442 return err;
1443 }
1444 EXPORT_SYMBOL(netlink_change_ngroups);
1445
1446 /**
1447 * netlink_clear_multicast_users - kick off multicast listeners
1448 *
1449 * This function removes all listeners from the given group.
1450 * @ksk: The kernel netlink socket, as returned by
1451 * netlink_kernel_create().
1452 * @group: The multicast group to clear.
1453 */
1454 void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
1455 {
1456 struct sock *sk;
1457 struct hlist_node *node;
1458 struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
1459
1460 netlink_table_grab();
1461
1462 sk_for_each_bound(sk, node, &tbl->mc_list)
1463 netlink_update_socket_mc(nlk_sk(sk), group, 0);
1464
1465 netlink_table_ungrab();
1466 }
1467 EXPORT_SYMBOL(netlink_clear_multicast_users);
1468
1469 void netlink_set_nonroot(int protocol, unsigned int flags)
1470 {
1471 if ((unsigned int)protocol < MAX_LINKS)
1472 nl_table[protocol].nl_nonroot = flags;
1473 }
1474 EXPORT_SYMBOL(netlink_set_nonroot);
1475
1476 static void netlink_destroy_callback(struct netlink_callback *cb)
1477 {
1478 if (cb->skb)
1479 kfree_skb(cb->skb);
1480 kfree(cb);
1481 }
1482
1483 /*
1484 * It looks a bit ugly.
1485 * It would be better to create kernel thread.
1486 */
1487
1488 static int netlink_dump(struct sock *sk)
1489 {
1490 struct netlink_sock *nlk = nlk_sk(sk);
1491 struct netlink_callback *cb;
1492 struct sk_buff *skb;
1493 struct nlmsghdr *nlh;
1494 int len, err = -ENOBUFS;
1495
1496 skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL);
1497 if (!skb)
1498 goto errout;
1499
1500 mutex_lock(nlk->cb_mutex);
1501
1502 cb = nlk->cb;
1503 if (cb == NULL) {
1504 err = -EINVAL;
1505 goto errout_skb;
1506 }
1507
1508 len = cb->dump(skb, cb);
1509
1510 if (len > 0) {
1511 mutex_unlock(nlk->cb_mutex);
1512 skb_queue_tail(&sk->sk_receive_queue, skb);
1513 sk->sk_data_ready(sk, len);
1514 return 0;
1515 }
1516
1517 nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
1518 if (!nlh)
1519 goto errout_skb;
1520
1521 memcpy(nlmsg_data(nlh), &len, sizeof(len));
1522
1523 skb_queue_tail(&sk->sk_receive_queue, skb);
1524 sk->sk_data_ready(sk, skb->len);
1525
1526 if (cb->done)
1527 cb->done(cb);
1528 nlk->cb = NULL;
1529 mutex_unlock(nlk->cb_mutex);
1530
1531 netlink_destroy_callback(cb);
1532 return 0;
1533
1534 errout_skb:
1535 mutex_unlock(nlk->cb_mutex);
1536 kfree_skb(skb);
1537 errout:
1538 return err;
1539 }
1540
1541 int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
1542 struct nlmsghdr *nlh,
1543 int (*dump)(struct sk_buff *skb,
1544 struct netlink_callback *),
1545 int (*done)(struct netlink_callback *))
1546 {
1547 struct netlink_callback *cb;
1548 struct sock *sk;
1549 struct netlink_sock *nlk;
1550
1551 cb = kzalloc(sizeof(*cb), GFP_KERNEL);
1552 if (cb == NULL)
1553 return -ENOBUFS;
1554
1555 cb->dump = dump;
1556 cb->done = done;
1557 cb->nlh = nlh;
1558 atomic_inc(&skb->users);
1559 cb->skb = skb;
1560
1561 sk = netlink_lookup(ssk->sk_net, ssk->sk_protocol, NETLINK_CB(skb).pid);
1562 if (sk == NULL) {
1563 netlink_destroy_callback(cb);
1564 return -ECONNREFUSED;
1565 }
1566 nlk = nlk_sk(sk);
1567 /* A dump is in progress... */
1568 mutex_lock(nlk->cb_mutex);
1569 if (nlk->cb) {
1570 mutex_unlock(nlk->cb_mutex);
1571 netlink_destroy_callback(cb);
1572 sock_put(sk);
1573 return -EBUSY;
1574 }
1575 nlk->cb = cb;
1576 mutex_unlock(nlk->cb_mutex);
1577
1578 netlink_dump(sk);
1579 sock_put(sk);
1580
1581 /* We successfully started a dump, by returning -EINTR we
1582 * signal not to send ACK even if it was requested.
1583 */
1584 return -EINTR;
1585 }
1586 EXPORT_SYMBOL(netlink_dump_start);
1587
1588 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
1589 {
1590 struct sk_buff *skb;
1591 struct nlmsghdr *rep;
1592 struct nlmsgerr *errmsg;
1593 size_t payload = sizeof(*errmsg);
1594
1595 /* error messages get the original request appened */
1596 if (err)
1597 payload += nlmsg_len(nlh);
1598
1599 skb = nlmsg_new(payload, GFP_KERNEL);
1600 if (!skb) {
1601 struct sock *sk;
1602
1603 sk = netlink_lookup(in_skb->sk->sk_net,
1604 in_skb->sk->sk_protocol,
1605 NETLINK_CB(in_skb).pid);
1606 if (sk) {
1607 sk->sk_err = ENOBUFS;
1608 sk->sk_error_report(sk);
1609 sock_put(sk);
1610 }
1611 return;
1612 }
1613
1614 rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
1615 NLMSG_ERROR, sizeof(struct nlmsgerr), 0);
1616 errmsg = nlmsg_data(rep);
1617 errmsg->error = err;
1618 memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
1619 netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
1620 }
1621 EXPORT_SYMBOL(netlink_ack);
1622
1623 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
1624 struct nlmsghdr *))
1625 {
1626 struct nlmsghdr *nlh;
1627 int err;
1628
1629 while (skb->len >= nlmsg_total_size(0)) {
1630 int msglen;
1631
1632 nlh = nlmsg_hdr(skb);
1633 err = 0;
1634
1635 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
1636 return 0;
1637
1638 /* Only requests are handled by the kernel */
1639 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
1640 goto ack;
1641
1642 /* Skip control messages */
1643 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
1644 goto ack;
1645
1646 err = cb(skb, nlh);
1647 if (err == -EINTR)
1648 goto skip;
1649
1650 ack:
1651 if (nlh->nlmsg_flags & NLM_F_ACK || err)
1652 netlink_ack(skb, nlh, err);
1653
1654 skip:
1655 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
1656 if (msglen > skb->len)
1657 msglen = skb->len;
1658 skb_pull(skb, msglen);
1659 }
1660
1661 return 0;
1662 }
1663 EXPORT_SYMBOL(netlink_rcv_skb);
1664
1665 /**
1666 * nlmsg_notify - send a notification netlink message
1667 * @sk: netlink socket to use
1668 * @skb: notification message
1669 * @pid: destination netlink pid for reports or 0
1670 * @group: destination multicast group or 0
1671 * @report: 1 to report back, 0 to disable
1672 * @flags: allocation flags
1673 */
1674 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,
1675 unsigned int group, int report, gfp_t flags)
1676 {
1677 int err = 0;
1678
1679 if (group) {
1680 int exclude_pid = 0;
1681
1682 if (report) {
1683 atomic_inc(&skb->users);
1684 exclude_pid = pid;
1685 }
1686
1687 /* errors reported via destination sk->sk_err */
1688 nlmsg_multicast(sk, skb, exclude_pid, group, flags);
1689 }
1690
1691 if (report)
1692 err = nlmsg_unicast(sk, skb, pid);
1693
1694 return err;
1695 }
1696 EXPORT_SYMBOL(nlmsg_notify);
1697
1698 #ifdef CONFIG_PROC_FS
1699 struct nl_seq_iter {
1700 struct seq_net_private p;
1701 int link;
1702 int hash_idx;
1703 };
1704
1705 static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
1706 {
1707 struct nl_seq_iter *iter = seq->private;
1708 int i, j;
1709 struct sock *s;
1710 struct hlist_node *node;
1711 loff_t off = 0;
1712
1713 for (i = 0; i < MAX_LINKS; i++) {
1714 struct nl_pid_hash *hash = &nl_table[i].hash;
1715
1716 for (j = 0; j <= hash->mask; j++) {
1717 sk_for_each(s, node, &hash->table[j]) {
1718 if (iter->p.net != s->sk_net)
1719 continue;
1720 if (off == pos) {
1721 iter->link = i;
1722 iter->hash_idx = j;
1723 return s;
1724 }
1725 ++off;
1726 }
1727 }
1728 }
1729 return NULL;
1730 }
1731
1732 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
1733 __acquires(nl_table_lock)
1734 {
1735 read_lock(&nl_table_lock);
1736 return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1737 }
1738
1739 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1740 {
1741 struct sock *s;
1742 struct nl_seq_iter *iter;
1743 int i, j;
1744
1745 ++*pos;
1746
1747 if (v == SEQ_START_TOKEN)
1748 return netlink_seq_socket_idx(seq, 0);
1749
1750 iter = seq->private;
1751 s = v;
1752 do {
1753 s = sk_next(s);
1754 } while (s && (iter->p.net != s->sk_net));
1755 if (s)
1756 return s;
1757
1758 i = iter->link;
1759 j = iter->hash_idx + 1;
1760
1761 do {
1762 struct nl_pid_hash *hash = &nl_table[i].hash;
1763
1764 for (; j <= hash->mask; j++) {
1765 s = sk_head(&hash->table[j]);
1766 while (s && (iter->p.net != s->sk_net))
1767 s = sk_next(s);
1768 if (s) {
1769 iter->link = i;
1770 iter->hash_idx = j;
1771 return s;
1772 }
1773 }
1774
1775 j = 0;
1776 } while (++i < MAX_LINKS);
1777
1778 return NULL;
1779 }
1780
1781 static void netlink_seq_stop(struct seq_file *seq, void *v)
1782 __releases(nl_table_lock)
1783 {
1784 read_unlock(&nl_table_lock);
1785 }
1786
1787
1788 static int netlink_seq_show(struct seq_file *seq, void *v)
1789 {
1790 if (v == SEQ_START_TOKEN)
1791 seq_puts(seq,
1792 "sk Eth Pid Groups "
1793 "Rmem Wmem Dump Locks\n");
1794 else {
1795 struct sock *s = v;
1796 struct netlink_sock *nlk = nlk_sk(s);
1797
1798 seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %d\n",
1799 s,
1800 s->sk_protocol,
1801 nlk->pid,
1802 nlk->groups ? (u32)nlk->groups[0] : 0,
1803 atomic_read(&s->sk_rmem_alloc),
1804 atomic_read(&s->sk_wmem_alloc),
1805 nlk->cb,
1806 atomic_read(&s->sk_refcnt)
1807 );
1808
1809 }
1810 return 0;
1811 }
1812
1813 static const struct seq_operations netlink_seq_ops = {
1814 .start = netlink_seq_start,
1815 .next = netlink_seq_next,
1816 .stop = netlink_seq_stop,
1817 .show = netlink_seq_show,
1818 };
1819
1820
1821 static int netlink_seq_open(struct inode *inode, struct file *file)
1822 {
1823 return seq_open_net(inode, file, &netlink_seq_ops,
1824 sizeof(struct nl_seq_iter));
1825 }
1826
1827 static const struct file_operations netlink_seq_fops = {
1828 .owner = THIS_MODULE,
1829 .open = netlink_seq_open,
1830 .read = seq_read,
1831 .llseek = seq_lseek,
1832 .release = seq_release_net,
1833 };
1834
1835 #endif
1836
1837 int netlink_register_notifier(struct notifier_block *nb)
1838 {
1839 return atomic_notifier_chain_register(&netlink_chain, nb);
1840 }
1841 EXPORT_SYMBOL(netlink_register_notifier);
1842
1843 int netlink_unregister_notifier(struct notifier_block *nb)
1844 {
1845 return atomic_notifier_chain_unregister(&netlink_chain, nb);
1846 }
1847 EXPORT_SYMBOL(netlink_unregister_notifier);
1848
1849 static const struct proto_ops netlink_ops = {
1850 .family = PF_NETLINK,
1851 .owner = THIS_MODULE,
1852 .release = netlink_release,
1853 .bind = netlink_bind,
1854 .connect = netlink_connect,
1855 .socketpair = sock_no_socketpair,
1856 .accept = sock_no_accept,
1857 .getname = netlink_getname,
1858 .poll = datagram_poll,
1859 .ioctl = sock_no_ioctl,
1860 .listen = sock_no_listen,
1861 .shutdown = sock_no_shutdown,
1862 .setsockopt = netlink_setsockopt,
1863 .getsockopt = netlink_getsockopt,
1864 .sendmsg = netlink_sendmsg,
1865 .recvmsg = netlink_recvmsg,
1866 .mmap = sock_no_mmap,
1867 .sendpage = sock_no_sendpage,
1868 };
1869
1870 static struct net_proto_family netlink_family_ops = {
1871 .family = PF_NETLINK,
1872 .create = netlink_create,
1873 .owner = THIS_MODULE, /* for consistency 8) */
1874 };
1875
1876 static int __net_init netlink_net_init(struct net *net)
1877 {
1878 #ifdef CONFIG_PROC_FS
1879 if (!proc_net_fops_create(net, "netlink", 0, &netlink_seq_fops))
1880 return -ENOMEM;
1881 #endif
1882 return 0;
1883 }
1884
1885 static void __net_exit netlink_net_exit(struct net *net)
1886 {
1887 #ifdef CONFIG_PROC_FS
1888 proc_net_remove(net, "netlink");
1889 #endif
1890 }
1891
1892 static struct pernet_operations __net_initdata netlink_net_ops = {
1893 .init = netlink_net_init,
1894 .exit = netlink_net_exit,
1895 };
1896
1897 static int __init netlink_proto_init(void)
1898 {
1899 struct sk_buff *dummy_skb;
1900 int i;
1901 unsigned long limit;
1902 unsigned int order;
1903 int err = proto_register(&netlink_proto, 0);
1904
1905 if (err != 0)
1906 goto out;
1907
1908 BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof(dummy_skb->cb));
1909
1910 nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
1911 if (!nl_table)
1912 goto panic;
1913
1914 if (num_physpages >= (128 * 1024))
1915 limit = num_physpages >> (21 - PAGE_SHIFT);
1916 else
1917 limit = num_physpages >> (23 - PAGE_SHIFT);
1918
1919 order = get_bitmask_order(limit) - 1 + PAGE_SHIFT;
1920 limit = (1UL << order) / sizeof(struct hlist_head);
1921 order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1;
1922
1923 for (i = 0; i < MAX_LINKS; i++) {
1924 struct nl_pid_hash *hash = &nl_table[i].hash;
1925
1926 hash->table = nl_pid_hash_zalloc(1 * sizeof(*hash->table));
1927 if (!hash->table) {
1928 while (i-- > 0)
1929 nl_pid_hash_free(nl_table[i].hash.table,
1930 1 * sizeof(*hash->table));
1931 kfree(nl_table);
1932 goto panic;
1933 }
1934 hash->max_shift = order;
1935 hash->shift = 0;
1936 hash->mask = 0;
1937 hash->rehash_time = jiffies;
1938 }
1939
1940 sock_register(&netlink_family_ops);
1941 register_pernet_subsys(&netlink_net_ops);
1942 /* The netlink device handler may be needed early. */
1943 rtnetlink_init();
1944 out:
1945 return err;
1946 panic:
1947 panic("netlink_init: Cannot allocate nl_table\n");
1948 }
1949
1950 core_initcall(netlink_proto_init);
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