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Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block
[deliverable/linux.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 BUG_ON(nl_table[sk->sk_protocol].registered == 0);
502 if (--nl_table[sk->sk_protocol].registered == 0) {
503 kfree(nl_table[sk->sk_protocol].listeners);
504 nl_table[sk->sk_protocol].module = NULL;
505 nl_table[sk->sk_protocol].registered = 0;
506 }
507 } else if (nlk->subscriptions)
508 netlink_update_listeners(sk);
509 netlink_table_ungrab();
510
511 kfree(nlk->groups);
512 nlk->groups = NULL;
513
514 sock_put(sk);
515 return 0;
516 }
517
518 static int netlink_autobind(struct socket *sock)
519 {
520 struct sock *sk = sock->sk;
521 struct net *net = sk->sk_net;
522 struct nl_pid_hash *hash = &nl_table[sk->sk_protocol].hash;
523 struct hlist_head *head;
524 struct sock *osk;
525 struct hlist_node *node;
526 s32 pid = current->tgid;
527 int err;
528 static s32 rover = -4097;
529
530 retry:
531 cond_resched();
532 netlink_table_grab();
533 head = nl_pid_hashfn(hash, pid);
534 sk_for_each(osk, node, head) {
535 if ((osk->sk_net != net))
536 continue;
537 if (nlk_sk(osk)->pid == pid) {
538 /* Bind collision, search negative pid values. */
539 pid = rover--;
540 if (rover > -4097)
541 rover = -4097;
542 netlink_table_ungrab();
543 goto retry;
544 }
545 }
546 netlink_table_ungrab();
547
548 err = netlink_insert(sk, net, pid);
549 if (err == -EADDRINUSE)
550 goto retry;
551
552 /* If 2 threads race to autobind, that is fine. */
553 if (err == -EBUSY)
554 err = 0;
555
556 return err;
557 }
558
559 static inline int netlink_capable(struct socket *sock, unsigned int flag)
560 {
561 return (nl_table[sock->sk->sk_protocol].nl_nonroot & flag) ||
562 capable(CAP_NET_ADMIN);
563 }
564
565 static void
566 netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
567 {
568 struct netlink_sock *nlk = nlk_sk(sk);
569
570 if (nlk->subscriptions && !subscriptions)
571 __sk_del_bind_node(sk);
572 else if (!nlk->subscriptions && subscriptions)
573 sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
574 nlk->subscriptions = subscriptions;
575 }
576
577 static int netlink_realloc_groups(struct sock *sk)
578 {
579 struct netlink_sock *nlk = nlk_sk(sk);
580 unsigned int groups;
581 unsigned long *new_groups;
582 int err = 0;
583
584 netlink_table_grab();
585
586 groups = nl_table[sk->sk_protocol].groups;
587 if (!nl_table[sk->sk_protocol].registered) {
588 err = -ENOENT;
589 goto out_unlock;
590 }
591
592 if (nlk->ngroups >= groups)
593 goto out_unlock;
594
595 new_groups = krealloc(nlk->groups, NLGRPSZ(groups), GFP_ATOMIC);
596 if (new_groups == NULL) {
597 err = -ENOMEM;
598 goto out_unlock;
599 }
600 memset((char *)new_groups + NLGRPSZ(nlk->ngroups), 0,
601 NLGRPSZ(groups) - NLGRPSZ(nlk->ngroups));
602
603 nlk->groups = new_groups;
604 nlk->ngroups = groups;
605 out_unlock:
606 netlink_table_ungrab();
607 return err;
608 }
609
610 static int netlink_bind(struct socket *sock, struct sockaddr *addr,
611 int addr_len)
612 {
613 struct sock *sk = sock->sk;
614 struct net *net = sk->sk_net;
615 struct netlink_sock *nlk = nlk_sk(sk);
616 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
617 int err;
618
619 if (nladdr->nl_family != AF_NETLINK)
620 return -EINVAL;
621
622 /* Only superuser is allowed to listen multicasts */
623 if (nladdr->nl_groups) {
624 if (!netlink_capable(sock, NL_NONROOT_RECV))
625 return -EPERM;
626 err = netlink_realloc_groups(sk);
627 if (err)
628 return err;
629 }
630
631 if (nlk->pid) {
632 if (nladdr->nl_pid != nlk->pid)
633 return -EINVAL;
634 } else {
635 err = nladdr->nl_pid ?
636 netlink_insert(sk, net, nladdr->nl_pid) :
637 netlink_autobind(sock);
638 if (err)
639 return err;
640 }
641
642 if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
643 return 0;
644
645 netlink_table_grab();
646 netlink_update_subscriptions(sk, nlk->subscriptions +
647 hweight32(nladdr->nl_groups) -
648 hweight32(nlk->groups[0]));
649 nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups;
650 netlink_update_listeners(sk);
651 netlink_table_ungrab();
652
653 return 0;
654 }
655
656 static int netlink_connect(struct socket *sock, struct sockaddr *addr,
657 int alen, int flags)
658 {
659 int err = 0;
660 struct sock *sk = sock->sk;
661 struct netlink_sock *nlk = nlk_sk(sk);
662 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
663
664 if (addr->sa_family == AF_UNSPEC) {
665 sk->sk_state = NETLINK_UNCONNECTED;
666 nlk->dst_pid = 0;
667 nlk->dst_group = 0;
668 return 0;
669 }
670 if (addr->sa_family != AF_NETLINK)
671 return -EINVAL;
672
673 /* Only superuser is allowed to send multicasts */
674 if (nladdr->nl_groups && !netlink_capable(sock, NL_NONROOT_SEND))
675 return -EPERM;
676
677 if (!nlk->pid)
678 err = netlink_autobind(sock);
679
680 if (err == 0) {
681 sk->sk_state = NETLINK_CONNECTED;
682 nlk->dst_pid = nladdr->nl_pid;
683 nlk->dst_group = ffs(nladdr->nl_groups);
684 }
685
686 return err;
687 }
688
689 static int netlink_getname(struct socket *sock, struct sockaddr *addr,
690 int *addr_len, int peer)
691 {
692 struct sock *sk = sock->sk;
693 struct netlink_sock *nlk = nlk_sk(sk);
694 struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
695
696 nladdr->nl_family = AF_NETLINK;
697 nladdr->nl_pad = 0;
698 *addr_len = sizeof(*nladdr);
699
700 if (peer) {
701 nladdr->nl_pid = nlk->dst_pid;
702 nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
703 } else {
704 nladdr->nl_pid = nlk->pid;
705 nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0;
706 }
707 return 0;
708 }
709
710 static void netlink_overrun(struct sock *sk)
711 {
712 if (!test_and_set_bit(0, &nlk_sk(sk)->state)) {
713 sk->sk_err = ENOBUFS;
714 sk->sk_error_report(sk);
715 }
716 }
717
718 static struct sock *netlink_getsockbypid(struct sock *ssk, u32 pid)
719 {
720 struct sock *sock;
721 struct netlink_sock *nlk;
722
723 sock = netlink_lookup(ssk->sk_net, ssk->sk_protocol, pid);
724 if (!sock)
725 return ERR_PTR(-ECONNREFUSED);
726
727 /* Don't bother queuing skb if kernel socket has no input function */
728 nlk = nlk_sk(sock);
729 if (sock->sk_state == NETLINK_CONNECTED &&
730 nlk->dst_pid != nlk_sk(ssk)->pid) {
731 sock_put(sock);
732 return ERR_PTR(-ECONNREFUSED);
733 }
734 return sock;
735 }
736
737 struct sock *netlink_getsockbyfilp(struct file *filp)
738 {
739 struct inode *inode = filp->f_path.dentry->d_inode;
740 struct sock *sock;
741
742 if (!S_ISSOCK(inode->i_mode))
743 return ERR_PTR(-ENOTSOCK);
744
745 sock = SOCKET_I(inode)->sk;
746 if (sock->sk_family != AF_NETLINK)
747 return ERR_PTR(-EINVAL);
748
749 sock_hold(sock);
750 return sock;
751 }
752
753 /*
754 * Attach a skb to a netlink socket.
755 * The caller must hold a reference to the destination socket. On error, the
756 * reference is dropped. The skb is not send to the destination, just all
757 * all error checks are performed and memory in the queue is reserved.
758 * Return values:
759 * < 0: error. skb freed, reference to sock dropped.
760 * 0: continue
761 * 1: repeat lookup - reference dropped while waiting for socket memory.
762 */
763 int netlink_attachskb(struct sock *sk, struct sk_buff *skb, int nonblock,
764 long *timeo, struct sock *ssk)
765 {
766 struct netlink_sock *nlk;
767
768 nlk = nlk_sk(sk);
769
770 if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
771 test_bit(0, &nlk->state)) {
772 DECLARE_WAITQUEUE(wait, current);
773 if (!*timeo) {
774 if (!ssk || netlink_is_kernel(ssk))
775 netlink_overrun(sk);
776 sock_put(sk);
777 kfree_skb(skb);
778 return -EAGAIN;
779 }
780
781 __set_current_state(TASK_INTERRUPTIBLE);
782 add_wait_queue(&nlk->wait, &wait);
783
784 if ((atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
785 test_bit(0, &nlk->state)) &&
786 !sock_flag(sk, SOCK_DEAD))
787 *timeo = schedule_timeout(*timeo);
788
789 __set_current_state(TASK_RUNNING);
790 remove_wait_queue(&nlk->wait, &wait);
791 sock_put(sk);
792
793 if (signal_pending(current)) {
794 kfree_skb(skb);
795 return sock_intr_errno(*timeo);
796 }
797 return 1;
798 }
799 skb_set_owner_r(skb, sk);
800 return 0;
801 }
802
803 int netlink_sendskb(struct sock *sk, struct sk_buff *skb)
804 {
805 int len = skb->len;
806
807 skb_queue_tail(&sk->sk_receive_queue, skb);
808 sk->sk_data_ready(sk, len);
809 sock_put(sk);
810 return len;
811 }
812
813 void netlink_detachskb(struct sock *sk, struct sk_buff *skb)
814 {
815 kfree_skb(skb);
816 sock_put(sk);
817 }
818
819 static inline struct sk_buff *netlink_trim(struct sk_buff *skb,
820 gfp_t allocation)
821 {
822 int delta;
823
824 skb_orphan(skb);
825
826 delta = skb->end - skb->tail;
827 if (delta * 2 < skb->truesize)
828 return skb;
829
830 if (skb_shared(skb)) {
831 struct sk_buff *nskb = skb_clone(skb, allocation);
832 if (!nskb)
833 return skb;
834 kfree_skb(skb);
835 skb = nskb;
836 }
837
838 if (!pskb_expand_head(skb, 0, -delta, allocation))
839 skb->truesize -= delta;
840
841 return skb;
842 }
843
844 static inline void netlink_rcv_wake(struct sock *sk)
845 {
846 struct netlink_sock *nlk = nlk_sk(sk);
847
848 if (skb_queue_empty(&sk->sk_receive_queue))
849 clear_bit(0, &nlk->state);
850 if (!test_bit(0, &nlk->state))
851 wake_up_interruptible(&nlk->wait);
852 }
853
854 static inline int netlink_unicast_kernel(struct sock *sk, struct sk_buff *skb)
855 {
856 int ret;
857 struct netlink_sock *nlk = nlk_sk(sk);
858
859 ret = -ECONNREFUSED;
860 if (nlk->netlink_rcv != NULL) {
861 ret = skb->len;
862 skb_set_owner_r(skb, sk);
863 nlk->netlink_rcv(skb);
864 }
865 kfree_skb(skb);
866 sock_put(sk);
867 return ret;
868 }
869
870 int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
871 u32 pid, int nonblock)
872 {
873 struct sock *sk;
874 int err;
875 long timeo;
876
877 skb = netlink_trim(skb, gfp_any());
878
879 timeo = sock_sndtimeo(ssk, nonblock);
880 retry:
881 sk = netlink_getsockbypid(ssk, pid);
882 if (IS_ERR(sk)) {
883 kfree_skb(skb);
884 return PTR_ERR(sk);
885 }
886 if (netlink_is_kernel(sk))
887 return netlink_unicast_kernel(sk, skb);
888
889 err = netlink_attachskb(sk, skb, nonblock, &timeo, ssk);
890 if (err == 1)
891 goto retry;
892 if (err)
893 return err;
894
895 return netlink_sendskb(sk, skb);
896 }
897 EXPORT_SYMBOL(netlink_unicast);
898
899 int netlink_has_listeners(struct sock *sk, unsigned int group)
900 {
901 int res = 0;
902 unsigned long *listeners;
903
904 BUG_ON(!netlink_is_kernel(sk));
905
906 rcu_read_lock();
907 listeners = rcu_dereference(nl_table[sk->sk_protocol].listeners);
908
909 if (group - 1 < nl_table[sk->sk_protocol].groups)
910 res = test_bit(group - 1, listeners);
911
912 rcu_read_unlock();
913
914 return res;
915 }
916 EXPORT_SYMBOL_GPL(netlink_has_listeners);
917
918 static inline int netlink_broadcast_deliver(struct sock *sk,
919 struct sk_buff *skb)
920 {
921 struct netlink_sock *nlk = nlk_sk(sk);
922
923 if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf &&
924 !test_bit(0, &nlk->state)) {
925 skb_set_owner_r(skb, sk);
926 skb_queue_tail(&sk->sk_receive_queue, skb);
927 sk->sk_data_ready(sk, skb->len);
928 return atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf;
929 }
930 return -1;
931 }
932
933 struct netlink_broadcast_data {
934 struct sock *exclude_sk;
935 struct net *net;
936 u32 pid;
937 u32 group;
938 int failure;
939 int congested;
940 int delivered;
941 gfp_t allocation;
942 struct sk_buff *skb, *skb2;
943 };
944
945 static inline int do_one_broadcast(struct sock *sk,
946 struct netlink_broadcast_data *p)
947 {
948 struct netlink_sock *nlk = nlk_sk(sk);
949 int val;
950
951 if (p->exclude_sk == sk)
952 goto out;
953
954 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
955 !test_bit(p->group - 1, nlk->groups))
956 goto out;
957
958 if ((sk->sk_net != p->net))
959 goto out;
960
961 if (p->failure) {
962 netlink_overrun(sk);
963 goto out;
964 }
965
966 sock_hold(sk);
967 if (p->skb2 == NULL) {
968 if (skb_shared(p->skb)) {
969 p->skb2 = skb_clone(p->skb, p->allocation);
970 } else {
971 p->skb2 = skb_get(p->skb);
972 /*
973 * skb ownership may have been set when
974 * delivered to a previous socket.
975 */
976 skb_orphan(p->skb2);
977 }
978 }
979 if (p->skb2 == NULL) {
980 netlink_overrun(sk);
981 /* Clone failed. Notify ALL listeners. */
982 p->failure = 1;
983 } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
984 netlink_overrun(sk);
985 } else {
986 p->congested |= val;
987 p->delivered = 1;
988 p->skb2 = NULL;
989 }
990 sock_put(sk);
991
992 out:
993 return 0;
994 }
995
996 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid,
997 u32 group, gfp_t allocation)
998 {
999 struct net *net = ssk->sk_net;
1000 struct netlink_broadcast_data info;
1001 struct hlist_node *node;
1002 struct sock *sk;
1003
1004 skb = netlink_trim(skb, allocation);
1005
1006 info.exclude_sk = ssk;
1007 info.net = net;
1008 info.pid = pid;
1009 info.group = group;
1010 info.failure = 0;
1011 info.congested = 0;
1012 info.delivered = 0;
1013 info.allocation = allocation;
1014 info.skb = skb;
1015 info.skb2 = NULL;
1016
1017 /* While we sleep in clone, do not allow to change socket list */
1018
1019 netlink_lock_table();
1020
1021 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1022 do_one_broadcast(sk, &info);
1023
1024 kfree_skb(skb);
1025
1026 netlink_unlock_table();
1027
1028 if (info.skb2)
1029 kfree_skb(info.skb2);
1030
1031 if (info.delivered) {
1032 if (info.congested && (allocation & __GFP_WAIT))
1033 yield();
1034 return 0;
1035 }
1036 if (info.failure)
1037 return -ENOBUFS;
1038 return -ESRCH;
1039 }
1040 EXPORT_SYMBOL(netlink_broadcast);
1041
1042 struct netlink_set_err_data {
1043 struct sock *exclude_sk;
1044 u32 pid;
1045 u32 group;
1046 int code;
1047 };
1048
1049 static inline int do_one_set_err(struct sock *sk,
1050 struct netlink_set_err_data *p)
1051 {
1052 struct netlink_sock *nlk = nlk_sk(sk);
1053
1054 if (sk == p->exclude_sk)
1055 goto out;
1056
1057 if (sk->sk_net != p->exclude_sk->sk_net)
1058 goto out;
1059
1060 if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
1061 !test_bit(p->group - 1, nlk->groups))
1062 goto out;
1063
1064 sk->sk_err = p->code;
1065 sk->sk_error_report(sk);
1066 out:
1067 return 0;
1068 }
1069
1070 void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
1071 {
1072 struct netlink_set_err_data info;
1073 struct hlist_node *node;
1074 struct sock *sk;
1075
1076 info.exclude_sk = ssk;
1077 info.pid = pid;
1078 info.group = group;
1079 info.code = code;
1080
1081 read_lock(&nl_table_lock);
1082
1083 sk_for_each_bound(sk, node, &nl_table[ssk->sk_protocol].mc_list)
1084 do_one_set_err(sk, &info);
1085
1086 read_unlock(&nl_table_lock);
1087 }
1088
1089 /* must be called with netlink table grabbed */
1090 static void netlink_update_socket_mc(struct netlink_sock *nlk,
1091 unsigned int group,
1092 int is_new)
1093 {
1094 int old, new = !!is_new, subscriptions;
1095
1096 old = test_bit(group - 1, nlk->groups);
1097 subscriptions = nlk->subscriptions - old + new;
1098 if (new)
1099 __set_bit(group - 1, nlk->groups);
1100 else
1101 __clear_bit(group - 1, nlk->groups);
1102 netlink_update_subscriptions(&nlk->sk, subscriptions);
1103 netlink_update_listeners(&nlk->sk);
1104 }
1105
1106 static int netlink_setsockopt(struct socket *sock, int level, int optname,
1107 char __user *optval, int optlen)
1108 {
1109 struct sock *sk = sock->sk;
1110 struct netlink_sock *nlk = nlk_sk(sk);
1111 unsigned int val = 0;
1112 int err;
1113
1114 if (level != SOL_NETLINK)
1115 return -ENOPROTOOPT;
1116
1117 if (optlen >= sizeof(int) &&
1118 get_user(val, (unsigned int __user *)optval))
1119 return -EFAULT;
1120
1121 switch (optname) {
1122 case NETLINK_PKTINFO:
1123 if (val)
1124 nlk->flags |= NETLINK_RECV_PKTINFO;
1125 else
1126 nlk->flags &= ~NETLINK_RECV_PKTINFO;
1127 err = 0;
1128 break;
1129 case NETLINK_ADD_MEMBERSHIP:
1130 case NETLINK_DROP_MEMBERSHIP: {
1131 if (!netlink_capable(sock, NL_NONROOT_RECV))
1132 return -EPERM;
1133 err = netlink_realloc_groups(sk);
1134 if (err)
1135 return err;
1136 if (!val || val - 1 >= nlk->ngroups)
1137 return -EINVAL;
1138 netlink_table_grab();
1139 netlink_update_socket_mc(nlk, val,
1140 optname == NETLINK_ADD_MEMBERSHIP);
1141 netlink_table_ungrab();
1142 err = 0;
1143 break;
1144 }
1145 default:
1146 err = -ENOPROTOOPT;
1147 }
1148 return err;
1149 }
1150
1151 static int netlink_getsockopt(struct socket *sock, int level, int optname,
1152 char __user *optval, int __user *optlen)
1153 {
1154 struct sock *sk = sock->sk;
1155 struct netlink_sock *nlk = nlk_sk(sk);
1156 int len, val, err;
1157
1158 if (level != SOL_NETLINK)
1159 return -ENOPROTOOPT;
1160
1161 if (get_user(len, optlen))
1162 return -EFAULT;
1163 if (len < 0)
1164 return -EINVAL;
1165
1166 switch (optname) {
1167 case NETLINK_PKTINFO:
1168 if (len < sizeof(int))
1169 return -EINVAL;
1170 len = sizeof(int);
1171 val = nlk->flags & NETLINK_RECV_PKTINFO ? 1 : 0;
1172 if (put_user(len, optlen) ||
1173 put_user(val, optval))
1174 return -EFAULT;
1175 err = 0;
1176 break;
1177 default:
1178 err = -ENOPROTOOPT;
1179 }
1180 return err;
1181 }
1182
1183 static void netlink_cmsg_recv_pktinfo(struct msghdr *msg, struct sk_buff *skb)
1184 {
1185 struct nl_pktinfo info;
1186
1187 info.group = NETLINK_CB(skb).dst_group;
1188 put_cmsg(msg, SOL_NETLINK, NETLINK_PKTINFO, sizeof(info), &info);
1189 }
1190
1191 static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
1192 struct msghdr *msg, size_t len)
1193 {
1194 struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1195 struct sock *sk = sock->sk;
1196 struct netlink_sock *nlk = nlk_sk(sk);
1197 struct sockaddr_nl *addr = msg->msg_name;
1198 u32 dst_pid;
1199 u32 dst_group;
1200 struct sk_buff *skb;
1201 int err;
1202 struct scm_cookie scm;
1203
1204 if (msg->msg_flags&MSG_OOB)
1205 return -EOPNOTSUPP;
1206
1207 if (NULL == siocb->scm)
1208 siocb->scm = &scm;
1209 err = scm_send(sock, msg, siocb->scm);
1210 if (err < 0)
1211 return err;
1212
1213 if (msg->msg_namelen) {
1214 if (addr->nl_family != AF_NETLINK)
1215 return -EINVAL;
1216 dst_pid = addr->nl_pid;
1217 dst_group = ffs(addr->nl_groups);
1218 if (dst_group && !netlink_capable(sock, NL_NONROOT_SEND))
1219 return -EPERM;
1220 } else {
1221 dst_pid = nlk->dst_pid;
1222 dst_group = nlk->dst_group;
1223 }
1224
1225 if (!nlk->pid) {
1226 err = netlink_autobind(sock);
1227 if (err)
1228 goto out;
1229 }
1230
1231 err = -EMSGSIZE;
1232 if (len > sk->sk_sndbuf - 32)
1233 goto out;
1234 err = -ENOBUFS;
1235 skb = alloc_skb(len, GFP_KERNEL);
1236 if (skb == NULL)
1237 goto out;
1238
1239 NETLINK_CB(skb).pid = nlk->pid;
1240 NETLINK_CB(skb).dst_group = dst_group;
1241 NETLINK_CB(skb).loginuid = audit_get_loginuid(current->audit_context);
1242 selinux_get_task_sid(current, &(NETLINK_CB(skb).sid));
1243 memcpy(NETLINK_CREDS(skb), &siocb->scm->creds, sizeof(struct ucred));
1244
1245 /* What can I do? Netlink is asynchronous, so that
1246 we will have to save current capabilities to
1247 check them, when this message will be delivered
1248 to corresponding kernel module. --ANK (980802)
1249 */
1250
1251 err = -EFAULT;
1252 if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
1253 kfree_skb(skb);
1254 goto out;
1255 }
1256
1257 err = security_netlink_send(sk, skb);
1258 if (err) {
1259 kfree_skb(skb);
1260 goto out;
1261 }
1262
1263 if (dst_group) {
1264 atomic_inc(&skb->users);
1265 netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL);
1266 }
1267 err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT);
1268
1269 out:
1270 return err;
1271 }
1272
1273 static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
1274 struct msghdr *msg, size_t len,
1275 int flags)
1276 {
1277 struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1278 struct scm_cookie scm;
1279 struct sock *sk = sock->sk;
1280 struct netlink_sock *nlk = nlk_sk(sk);
1281 int noblock = flags&MSG_DONTWAIT;
1282 size_t copied;
1283 struct sk_buff *skb;
1284 int err;
1285
1286 if (flags&MSG_OOB)
1287 return -EOPNOTSUPP;
1288
1289 copied = 0;
1290
1291 skb = skb_recv_datagram(sk, flags, noblock, &err);
1292 if (skb == NULL)
1293 goto out;
1294
1295 msg->msg_namelen = 0;
1296
1297 copied = skb->len;
1298 if (len < copied) {
1299 msg->msg_flags |= MSG_TRUNC;
1300 copied = len;
1301 }
1302
1303 skb_reset_transport_header(skb);
1304 err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
1305
1306 if (msg->msg_name) {
1307 struct sockaddr_nl *addr = (struct sockaddr_nl *)msg->msg_name;
1308 addr->nl_family = AF_NETLINK;
1309 addr->nl_pad = 0;
1310 addr->nl_pid = NETLINK_CB(skb).pid;
1311 addr->nl_groups = netlink_group_mask(NETLINK_CB(skb).dst_group);
1312 msg->msg_namelen = sizeof(*addr);
1313 }
1314
1315 if (nlk->flags & NETLINK_RECV_PKTINFO)
1316 netlink_cmsg_recv_pktinfo(msg, skb);
1317
1318 if (NULL == siocb->scm) {
1319 memset(&scm, 0, sizeof(scm));
1320 siocb->scm = &scm;
1321 }
1322 siocb->scm->creds = *NETLINK_CREDS(skb);
1323 if (flags & MSG_TRUNC)
1324 copied = skb->len;
1325 skb_free_datagram(sk, skb);
1326
1327 if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2)
1328 netlink_dump(sk);
1329
1330 scm_recv(sock, msg, siocb->scm, flags);
1331 out:
1332 netlink_rcv_wake(sk);
1333 return err ? : copied;
1334 }
1335
1336 static void netlink_data_ready(struct sock *sk, int len)
1337 {
1338 BUG();
1339 }
1340
1341 /*
1342 * We export these functions to other modules. They provide a
1343 * complete set of kernel non-blocking support for message
1344 * queueing.
1345 */
1346
1347 static void __netlink_release(struct sock *sk)
1348 {
1349 /*
1350 * Last sock_put should drop referrence to sk->sk_net. It has already
1351 * been dropped in netlink_kernel_create. Taking referrence to stopping
1352 * namespace is not an option.
1353 * Take referrence to a socket to remove it from netlink lookup table
1354 * _alive_ and after that destroy it in the context of init_net.
1355 */
1356
1357 sock_hold(sk);
1358 sock_release(sk->sk_socket);
1359 sk->sk_net = get_net(&init_net);
1360 sock_put(sk);
1361 }
1362
1363 struct sock *
1364 netlink_kernel_create(struct net *net, int unit, unsigned int groups,
1365 void (*input)(struct sk_buff *skb),
1366 struct mutex *cb_mutex, struct module *module)
1367 {
1368 struct socket *sock;
1369 struct sock *sk;
1370 struct netlink_sock *nlk;
1371 unsigned long *listeners = NULL;
1372
1373 BUG_ON(!nl_table);
1374
1375 if (unit < 0 || unit >= MAX_LINKS)
1376 return NULL;
1377
1378 if (sock_create_lite(PF_NETLINK, SOCK_DGRAM, unit, &sock))
1379 return NULL;
1380
1381 /*
1382 * We have to just have a reference on the net from sk, but don't
1383 * get_net it. Besides, we cannot get and then put the net here.
1384 * So we create one inside init_net and the move it to net.
1385 */
1386
1387 if (__netlink_create(&init_net, sock, cb_mutex, unit) < 0)
1388 goto out_sock_release_nosk;
1389
1390 sk = sock->sk;
1391 put_net(sk->sk_net);
1392 sk->sk_net = net;
1393
1394 if (groups < 32)
1395 groups = 32;
1396
1397 listeners = kzalloc(NLGRPSZ(groups), GFP_KERNEL);
1398 if (!listeners)
1399 goto out_sock_release;
1400
1401 sk->sk_data_ready = netlink_data_ready;
1402 if (input)
1403 nlk_sk(sk)->netlink_rcv = input;
1404
1405 if (netlink_insert(sk, net, 0))
1406 goto out_sock_release;
1407
1408 nlk = nlk_sk(sk);
1409 nlk->flags |= NETLINK_KERNEL_SOCKET;
1410
1411 netlink_table_grab();
1412 if (!nl_table[unit].registered) {
1413 nl_table[unit].groups = groups;
1414 nl_table[unit].listeners = listeners;
1415 nl_table[unit].cb_mutex = cb_mutex;
1416 nl_table[unit].module = module;
1417 nl_table[unit].registered = 1;
1418 } else {
1419 kfree(listeners);
1420 nl_table[unit].registered++;
1421 }
1422 netlink_table_ungrab();
1423 return sk;
1424
1425 out_sock_release:
1426 kfree(listeners);
1427 __netlink_release(sk);
1428 return NULL;
1429
1430 out_sock_release_nosk:
1431 sock_release(sock);
1432 return NULL;
1433 }
1434 EXPORT_SYMBOL(netlink_kernel_create);
1435
1436
1437 void
1438 netlink_kernel_release(struct sock *sk)
1439 {
1440 if (sk == NULL || sk->sk_socket == NULL)
1441 return;
1442
1443 __netlink_release(sk);
1444 }
1445 EXPORT_SYMBOL(netlink_kernel_release);
1446
1447
1448 /**
1449 * netlink_change_ngroups - change number of multicast groups
1450 *
1451 * This changes the number of multicast groups that are available
1452 * on a certain netlink family. Note that it is not possible to
1453 * change the number of groups to below 32. Also note that it does
1454 * not implicitly call netlink_clear_multicast_users() when the
1455 * number of groups is reduced.
1456 *
1457 * @sk: The kernel netlink socket, as returned by netlink_kernel_create().
1458 * @groups: The new number of groups.
1459 */
1460 int netlink_change_ngroups(struct sock *sk, unsigned int groups)
1461 {
1462 unsigned long *listeners, *old = NULL;
1463 struct netlink_table *tbl = &nl_table[sk->sk_protocol];
1464 int err = 0;
1465
1466 if (groups < 32)
1467 groups = 32;
1468
1469 netlink_table_grab();
1470 if (NLGRPSZ(tbl->groups) < NLGRPSZ(groups)) {
1471 listeners = kzalloc(NLGRPSZ(groups), GFP_ATOMIC);
1472 if (!listeners) {
1473 err = -ENOMEM;
1474 goto out_ungrab;
1475 }
1476 old = tbl->listeners;
1477 memcpy(listeners, old, NLGRPSZ(tbl->groups));
1478 rcu_assign_pointer(tbl->listeners, listeners);
1479 }
1480 tbl->groups = groups;
1481
1482 out_ungrab:
1483 netlink_table_ungrab();
1484 synchronize_rcu();
1485 kfree(old);
1486 return err;
1487 }
1488 EXPORT_SYMBOL(netlink_change_ngroups);
1489
1490 /**
1491 * netlink_clear_multicast_users - kick off multicast listeners
1492 *
1493 * This function removes all listeners from the given group.
1494 * @ksk: The kernel netlink socket, as returned by
1495 * netlink_kernel_create().
1496 * @group: The multicast group to clear.
1497 */
1498 void netlink_clear_multicast_users(struct sock *ksk, unsigned int group)
1499 {
1500 struct sock *sk;
1501 struct hlist_node *node;
1502 struct netlink_table *tbl = &nl_table[ksk->sk_protocol];
1503
1504 netlink_table_grab();
1505
1506 sk_for_each_bound(sk, node, &tbl->mc_list)
1507 netlink_update_socket_mc(nlk_sk(sk), group, 0);
1508
1509 netlink_table_ungrab();
1510 }
1511 EXPORT_SYMBOL(netlink_clear_multicast_users);
1512
1513 void netlink_set_nonroot(int protocol, unsigned int flags)
1514 {
1515 if ((unsigned int)protocol < MAX_LINKS)
1516 nl_table[protocol].nl_nonroot = flags;
1517 }
1518 EXPORT_SYMBOL(netlink_set_nonroot);
1519
1520 static void netlink_destroy_callback(struct netlink_callback *cb)
1521 {
1522 if (cb->skb)
1523 kfree_skb(cb->skb);
1524 kfree(cb);
1525 }
1526
1527 /*
1528 * It looks a bit ugly.
1529 * It would be better to create kernel thread.
1530 */
1531
1532 static int netlink_dump(struct sock *sk)
1533 {
1534 struct netlink_sock *nlk = nlk_sk(sk);
1535 struct netlink_callback *cb;
1536 struct sk_buff *skb;
1537 struct nlmsghdr *nlh;
1538 int len, err = -ENOBUFS;
1539
1540 skb = sock_rmalloc(sk, NLMSG_GOODSIZE, 0, GFP_KERNEL);
1541 if (!skb)
1542 goto errout;
1543
1544 mutex_lock(nlk->cb_mutex);
1545
1546 cb = nlk->cb;
1547 if (cb == NULL) {
1548 err = -EINVAL;
1549 goto errout_skb;
1550 }
1551
1552 len = cb->dump(skb, cb);
1553
1554 if (len > 0) {
1555 mutex_unlock(nlk->cb_mutex);
1556 skb_queue_tail(&sk->sk_receive_queue, skb);
1557 sk->sk_data_ready(sk, len);
1558 return 0;
1559 }
1560
1561 nlh = nlmsg_put_answer(skb, cb, NLMSG_DONE, sizeof(len), NLM_F_MULTI);
1562 if (!nlh)
1563 goto errout_skb;
1564
1565 memcpy(nlmsg_data(nlh), &len, sizeof(len));
1566
1567 skb_queue_tail(&sk->sk_receive_queue, skb);
1568 sk->sk_data_ready(sk, skb->len);
1569
1570 if (cb->done)
1571 cb->done(cb);
1572 nlk->cb = NULL;
1573 mutex_unlock(nlk->cb_mutex);
1574
1575 netlink_destroy_callback(cb);
1576 return 0;
1577
1578 errout_skb:
1579 mutex_unlock(nlk->cb_mutex);
1580 kfree_skb(skb);
1581 errout:
1582 return err;
1583 }
1584
1585 int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
1586 struct nlmsghdr *nlh,
1587 int (*dump)(struct sk_buff *skb,
1588 struct netlink_callback *),
1589 int (*done)(struct netlink_callback *))
1590 {
1591 struct netlink_callback *cb;
1592 struct sock *sk;
1593 struct netlink_sock *nlk;
1594
1595 cb = kzalloc(sizeof(*cb), GFP_KERNEL);
1596 if (cb == NULL)
1597 return -ENOBUFS;
1598
1599 cb->dump = dump;
1600 cb->done = done;
1601 cb->nlh = nlh;
1602 atomic_inc(&skb->users);
1603 cb->skb = skb;
1604
1605 sk = netlink_lookup(ssk->sk_net, ssk->sk_protocol, NETLINK_CB(skb).pid);
1606 if (sk == NULL) {
1607 netlink_destroy_callback(cb);
1608 return -ECONNREFUSED;
1609 }
1610 nlk = nlk_sk(sk);
1611 /* A dump is in progress... */
1612 mutex_lock(nlk->cb_mutex);
1613 if (nlk->cb) {
1614 mutex_unlock(nlk->cb_mutex);
1615 netlink_destroy_callback(cb);
1616 sock_put(sk);
1617 return -EBUSY;
1618 }
1619 nlk->cb = cb;
1620 mutex_unlock(nlk->cb_mutex);
1621
1622 netlink_dump(sk);
1623 sock_put(sk);
1624
1625 /* We successfully started a dump, by returning -EINTR we
1626 * signal not to send ACK even if it was requested.
1627 */
1628 return -EINTR;
1629 }
1630 EXPORT_SYMBOL(netlink_dump_start);
1631
1632 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err)
1633 {
1634 struct sk_buff *skb;
1635 struct nlmsghdr *rep;
1636 struct nlmsgerr *errmsg;
1637 size_t payload = sizeof(*errmsg);
1638
1639 /* error messages get the original request appened */
1640 if (err)
1641 payload += nlmsg_len(nlh);
1642
1643 skb = nlmsg_new(payload, GFP_KERNEL);
1644 if (!skb) {
1645 struct sock *sk;
1646
1647 sk = netlink_lookup(in_skb->sk->sk_net,
1648 in_skb->sk->sk_protocol,
1649 NETLINK_CB(in_skb).pid);
1650 if (sk) {
1651 sk->sk_err = ENOBUFS;
1652 sk->sk_error_report(sk);
1653 sock_put(sk);
1654 }
1655 return;
1656 }
1657
1658 rep = __nlmsg_put(skb, NETLINK_CB(in_skb).pid, nlh->nlmsg_seq,
1659 NLMSG_ERROR, sizeof(struct nlmsgerr), 0);
1660 errmsg = nlmsg_data(rep);
1661 errmsg->error = err;
1662 memcpy(&errmsg->msg, nlh, err ? nlh->nlmsg_len : sizeof(*nlh));
1663 netlink_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).pid, MSG_DONTWAIT);
1664 }
1665 EXPORT_SYMBOL(netlink_ack);
1666
1667 int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
1668 struct nlmsghdr *))
1669 {
1670 struct nlmsghdr *nlh;
1671 int err;
1672
1673 while (skb->len >= nlmsg_total_size(0)) {
1674 int msglen;
1675
1676 nlh = nlmsg_hdr(skb);
1677 err = 0;
1678
1679 if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
1680 return 0;
1681
1682 /* Only requests are handled by the kernel */
1683 if (!(nlh->nlmsg_flags & NLM_F_REQUEST))
1684 goto ack;
1685
1686 /* Skip control messages */
1687 if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
1688 goto ack;
1689
1690 err = cb(skb, nlh);
1691 if (err == -EINTR)
1692 goto skip;
1693
1694 ack:
1695 if (nlh->nlmsg_flags & NLM_F_ACK || err)
1696 netlink_ack(skb, nlh, err);
1697
1698 skip:
1699 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
1700 if (msglen > skb->len)
1701 msglen = skb->len;
1702 skb_pull(skb, msglen);
1703 }
1704
1705 return 0;
1706 }
1707 EXPORT_SYMBOL(netlink_rcv_skb);
1708
1709 /**
1710 * nlmsg_notify - send a notification netlink message
1711 * @sk: netlink socket to use
1712 * @skb: notification message
1713 * @pid: destination netlink pid for reports or 0
1714 * @group: destination multicast group or 0
1715 * @report: 1 to report back, 0 to disable
1716 * @flags: allocation flags
1717 */
1718 int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,
1719 unsigned int group, int report, gfp_t flags)
1720 {
1721 int err = 0;
1722
1723 if (group) {
1724 int exclude_pid = 0;
1725
1726 if (report) {
1727 atomic_inc(&skb->users);
1728 exclude_pid = pid;
1729 }
1730
1731 /* errors reported via destination sk->sk_err */
1732 nlmsg_multicast(sk, skb, exclude_pid, group, flags);
1733 }
1734
1735 if (report)
1736 err = nlmsg_unicast(sk, skb, pid);
1737
1738 return err;
1739 }
1740 EXPORT_SYMBOL(nlmsg_notify);
1741
1742 #ifdef CONFIG_PROC_FS
1743 struct nl_seq_iter {
1744 struct seq_net_private p;
1745 int link;
1746 int hash_idx;
1747 };
1748
1749 static struct sock *netlink_seq_socket_idx(struct seq_file *seq, loff_t pos)
1750 {
1751 struct nl_seq_iter *iter = seq->private;
1752 int i, j;
1753 struct sock *s;
1754 struct hlist_node *node;
1755 loff_t off = 0;
1756
1757 for (i = 0; i < MAX_LINKS; i++) {
1758 struct nl_pid_hash *hash = &nl_table[i].hash;
1759
1760 for (j = 0; j <= hash->mask; j++) {
1761 sk_for_each(s, node, &hash->table[j]) {
1762 if (iter->p.net != s->sk_net)
1763 continue;
1764 if (off == pos) {
1765 iter->link = i;
1766 iter->hash_idx = j;
1767 return s;
1768 }
1769 ++off;
1770 }
1771 }
1772 }
1773 return NULL;
1774 }
1775
1776 static void *netlink_seq_start(struct seq_file *seq, loff_t *pos)
1777 __acquires(nl_table_lock)
1778 {
1779 read_lock(&nl_table_lock);
1780 return *pos ? netlink_seq_socket_idx(seq, *pos - 1) : SEQ_START_TOKEN;
1781 }
1782
1783 static void *netlink_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1784 {
1785 struct sock *s;
1786 struct nl_seq_iter *iter;
1787 int i, j;
1788
1789 ++*pos;
1790
1791 if (v == SEQ_START_TOKEN)
1792 return netlink_seq_socket_idx(seq, 0);
1793
1794 iter = seq->private;
1795 s = v;
1796 do {
1797 s = sk_next(s);
1798 } while (s && (iter->p.net != s->sk_net));
1799 if (s)
1800 return s;
1801
1802 i = iter->link;
1803 j = iter->hash_idx + 1;
1804
1805 do {
1806 struct nl_pid_hash *hash = &nl_table[i].hash;
1807
1808 for (; j <= hash->mask; j++) {
1809 s = sk_head(&hash->table[j]);
1810 while (s && (iter->p.net != s->sk_net))
1811 s = sk_next(s);
1812 if (s) {
1813 iter->link = i;
1814 iter->hash_idx = j;
1815 return s;
1816 }
1817 }
1818
1819 j = 0;
1820 } while (++i < MAX_LINKS);
1821
1822 return NULL;
1823 }
1824
1825 static void netlink_seq_stop(struct seq_file *seq, void *v)
1826 __releases(nl_table_lock)
1827 {
1828 read_unlock(&nl_table_lock);
1829 }
1830
1831
1832 static int netlink_seq_show(struct seq_file *seq, void *v)
1833 {
1834 if (v == SEQ_START_TOKEN)
1835 seq_puts(seq,
1836 "sk Eth Pid Groups "
1837 "Rmem Wmem Dump Locks\n");
1838 else {
1839 struct sock *s = v;
1840 struct netlink_sock *nlk = nlk_sk(s);
1841
1842 seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %d\n",
1843 s,
1844 s->sk_protocol,
1845 nlk->pid,
1846 nlk->groups ? (u32)nlk->groups[0] : 0,
1847 atomic_read(&s->sk_rmem_alloc),
1848 atomic_read(&s->sk_wmem_alloc),
1849 nlk->cb,
1850 atomic_read(&s->sk_refcnt)
1851 );
1852
1853 }
1854 return 0;
1855 }
1856
1857 static const struct seq_operations netlink_seq_ops = {
1858 .start = netlink_seq_start,
1859 .next = netlink_seq_next,
1860 .stop = netlink_seq_stop,
1861 .show = netlink_seq_show,
1862 };
1863
1864
1865 static int netlink_seq_open(struct inode *inode, struct file *file)
1866 {
1867 return seq_open_net(inode, file, &netlink_seq_ops,
1868 sizeof(struct nl_seq_iter));
1869 }
1870
1871 static const struct file_operations netlink_seq_fops = {
1872 .owner = THIS_MODULE,
1873 .open = netlink_seq_open,
1874 .read = seq_read,
1875 .llseek = seq_lseek,
1876 .release = seq_release_net,
1877 };
1878
1879 #endif
1880
1881 int netlink_register_notifier(struct notifier_block *nb)
1882 {
1883 return atomic_notifier_chain_register(&netlink_chain, nb);
1884 }
1885 EXPORT_SYMBOL(netlink_register_notifier);
1886
1887 int netlink_unregister_notifier(struct notifier_block *nb)
1888 {
1889 return atomic_notifier_chain_unregister(&netlink_chain, nb);
1890 }
1891 EXPORT_SYMBOL(netlink_unregister_notifier);
1892
1893 static const struct proto_ops netlink_ops = {
1894 .family = PF_NETLINK,
1895 .owner = THIS_MODULE,
1896 .release = netlink_release,
1897 .bind = netlink_bind,
1898 .connect = netlink_connect,
1899 .socketpair = sock_no_socketpair,
1900 .accept = sock_no_accept,
1901 .getname = netlink_getname,
1902 .poll = datagram_poll,
1903 .ioctl = sock_no_ioctl,
1904 .listen = sock_no_listen,
1905 .shutdown = sock_no_shutdown,
1906 .setsockopt = netlink_setsockopt,
1907 .getsockopt = netlink_getsockopt,
1908 .sendmsg = netlink_sendmsg,
1909 .recvmsg = netlink_recvmsg,
1910 .mmap = sock_no_mmap,
1911 .sendpage = sock_no_sendpage,
1912 };
1913
1914 static struct net_proto_family netlink_family_ops = {
1915 .family = PF_NETLINK,
1916 .create = netlink_create,
1917 .owner = THIS_MODULE, /* for consistency 8) */
1918 };
1919
1920 static int __net_init netlink_net_init(struct net *net)
1921 {
1922 #ifdef CONFIG_PROC_FS
1923 if (!proc_net_fops_create(net, "netlink", 0, &netlink_seq_fops))
1924 return -ENOMEM;
1925 #endif
1926 return 0;
1927 }
1928
1929 static void __net_exit netlink_net_exit(struct net *net)
1930 {
1931 #ifdef CONFIG_PROC_FS
1932 proc_net_remove(net, "netlink");
1933 #endif
1934 }
1935
1936 static struct pernet_operations __net_initdata netlink_net_ops = {
1937 .init = netlink_net_init,
1938 .exit = netlink_net_exit,
1939 };
1940
1941 static int __init netlink_proto_init(void)
1942 {
1943 struct sk_buff *dummy_skb;
1944 int i;
1945 unsigned long limit;
1946 unsigned int order;
1947 int err = proto_register(&netlink_proto, 0);
1948
1949 if (err != 0)
1950 goto out;
1951
1952 BUILD_BUG_ON(sizeof(struct netlink_skb_parms) > sizeof(dummy_skb->cb));
1953
1954 nl_table = kcalloc(MAX_LINKS, sizeof(*nl_table), GFP_KERNEL);
1955 if (!nl_table)
1956 goto panic;
1957
1958 if (num_physpages >= (128 * 1024))
1959 limit = num_physpages >> (21 - PAGE_SHIFT);
1960 else
1961 limit = num_physpages >> (23 - PAGE_SHIFT);
1962
1963 order = get_bitmask_order(limit) - 1 + PAGE_SHIFT;
1964 limit = (1UL << order) / sizeof(struct hlist_head);
1965 order = get_bitmask_order(min(limit, (unsigned long)UINT_MAX)) - 1;
1966
1967 for (i = 0; i < MAX_LINKS; i++) {
1968 struct nl_pid_hash *hash = &nl_table[i].hash;
1969
1970 hash->table = nl_pid_hash_zalloc(1 * sizeof(*hash->table));
1971 if (!hash->table) {
1972 while (i-- > 0)
1973 nl_pid_hash_free(nl_table[i].hash.table,
1974 1 * sizeof(*hash->table));
1975 kfree(nl_table);
1976 goto panic;
1977 }
1978 hash->max_shift = order;
1979 hash->shift = 0;
1980 hash->mask = 0;
1981 hash->rehash_time = jiffies;
1982 }
1983
1984 sock_register(&netlink_family_ops);
1985 register_pernet_subsys(&netlink_net_ops);
1986 /* The netlink device handler may be needed early. */
1987 rtnetlink_init();
1988 out:
1989 return err;
1990 panic:
1991 panic("netlink_init: Cannot allocate nl_table\n");
1992 }
1993
1994 core_initcall(netlink_proto_init);
Linux kernel - Deliverables
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