aboutsummaryrefslogtreecommitdiffstats
path: root/net/phonet/socket.c
blob: 76d499f6af9ab32aa17422ef911497585b6649b7 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
// SPDX-License-Identifier: GPL-2.0-only
/*
 * File: socket.c
 *
 * Phonet sockets
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Authors: Sakari Ailus <sakari.ailus@nokia.com>
 *          Rémi Denis-Courmont
 */

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/poll.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/tcp_states.h>

#include <linux/phonet.h>
#include <linux/export.h>
#include <net/phonet/phonet.h>
#include <net/phonet/pep.h>
#include <net/phonet/pn_dev.h>

static int pn_socket_release(struct socket *sock)
{
	struct sock *sk = sock->sk;

	if (sk) {
		sock->sk = NULL;
		sk->sk_prot->close(sk, 0);
	}
	return 0;
}

#define PN_HASHSIZE	16
#define PN_HASHMASK	(PN_HASHSIZE-1)


static struct  {
	struct hlist_head hlist[PN_HASHSIZE];
	struct mutex lock;
} pnsocks;

void __init pn_sock_init(void)
{
	unsigned int i;

	for (i = 0; i < PN_HASHSIZE; i++)
		INIT_HLIST_HEAD(pnsocks.hlist + i);
	mutex_init(&pnsocks.lock);
}

static struct hlist_head *pn_hash_list(u16 obj)
{
	return pnsocks.hlist + (obj & PN_HASHMASK);
}

/*
 * Find address based on socket address, match only certain fields.
 * Also grab sock if it was found. Remember to sock_put it later.
 */
struct sock *pn_find_sock_by_sa(struct net *net, const struct sockaddr_pn *spn)
{
	struct sock *sknode;
	struct sock *rval = NULL;
	u16 obj = pn_sockaddr_get_object(spn);
	u8 res = spn->spn_resource;
	struct hlist_head *hlist = pn_hash_list(obj);

	rcu_read_lock();
	sk_for_each_rcu(sknode, hlist) {
		struct pn_sock *pn = pn_sk(sknode);
		BUG_ON(!pn->sobject); /* unbound socket */

		if (!net_eq(sock_net(sknode), net))
			continue;
		if (pn_port(obj)) {
			/* Look up socket by port */
			if (pn_port(pn->sobject) != pn_port(obj))
				continue;
		} else {
			/* If port is zero, look up by resource */
			if (pn->resource != res)
				continue;
		}
		if (pn_addr(pn->sobject) &&
		    pn_addr(pn->sobject) != pn_addr(obj))
			continue;

		rval = sknode;
		sock_hold(sknode);
		break;
	}
	rcu_read_unlock();

	return rval;
}

/* Deliver a broadcast packet (only in bottom-half) */
void pn_deliver_sock_broadcast(struct net *net, struct sk_buff *skb)
{
	struct hlist_head *hlist = pnsocks.hlist;
	unsigned int h;

	rcu_read_lock();
	for (h = 0; h < PN_HASHSIZE; h++) {
		struct sock *sknode;

		sk_for_each(sknode, hlist) {
			struct sk_buff *clone;

			if (!net_eq(sock_net(sknode), net))
				continue;
			if (!sock_flag(sknode, SOCK_BROADCAST))
				continue;

			clone = skb_clone(skb, GFP_ATOMIC);
			if (clone) {
				sock_hold(sknode);
				sk_receive_skb(sknode, clone, 0);
			}
		}
		hlist++;
	}
	rcu_read_unlock();
}

int pn_sock_hash(struct sock *sk)
{
	struct hlist_head *hlist = pn_hash_list(pn_sk(sk)->sobject);

	mutex_lock(&pnsocks.lock);
	sk_add_node_rcu(sk, hlist);
	mutex_unlock(&pnsocks.lock);

	return 0;
}
EXPORT_SYMBOL(pn_sock_hash);

void pn_sock_unhash(struct sock *sk)
{
	mutex_lock(&pnsocks.lock);
	sk_del_node_init_rcu(sk);
	mutex_unlock(&pnsocks.lock);
	pn_sock_unbind_all_res(sk);
	synchronize_rcu();
}
EXPORT_SYMBOL(pn_sock_unhash);

static DEFINE_MUTEX(port_mutex);

static int pn_socket_bind(struct socket *sock, struct sockaddr *addr, int len)
{
	struct sock *sk = sock->sk;
	struct pn_sock *pn = pn_sk(sk);
	struct sockaddr_pn *spn = (struct sockaddr_pn *)addr;
	int err;
	u16 handle;
	u8 saddr;

	if (sk->sk_prot->bind)
		return sk->sk_prot->bind(sk, addr, len);

	if (len < sizeof(struct sockaddr_pn))
		return -EINVAL;
	if (spn->spn_family != AF_PHONET)
		return -EAFNOSUPPORT;

	handle = pn_sockaddr_get_object((struct sockaddr_pn *)addr);
	saddr = pn_addr(handle);
	if (saddr && phonet_address_lookup(sock_net(sk), saddr))
		return -EADDRNOTAVAIL;

	lock_sock(sk);
	if (sk->sk_state != TCP_CLOSE || pn_port(pn->sobject)) {
		err = -EINVAL; /* attempt to rebind */
		goto out;
	}
	WARN_ON(sk_hashed(sk));
	mutex_lock(&port_mutex);
	err = sk->sk_prot->get_port(sk, pn_port(handle));
	if (err)
		goto out_port;

	/* get_port() sets the port, bind() sets the address if applicable */
	pn->sobject = pn_object(saddr, pn_port(pn->sobject));
	pn->resource = spn->spn_resource;

	/* Enable RX on the socket */
	err = sk->sk_prot->hash(sk);
out_port:
	mutex_unlock(&port_mutex);
out:
	release_sock(sk);
	return err;
}

static int pn_socket_autobind(struct socket *sock)
{
	struct sockaddr_pn sa;
	int err;

	memset(&sa, 0, sizeof(sa));
	sa.spn_family = AF_PHONET;
	err = pn_socket_bind(sock, (struct sockaddr *)&sa,
				sizeof(struct sockaddr_pn));
	if (err != -EINVAL)
		return err;
	BUG_ON(!pn_port(pn_sk(sock->sk)->sobject));
	return 0; /* socket was already bound */
}

static int pn_socket_connect(struct socket *sock, struct sockaddr *addr,
		int len, int flags)
{
	struct sock *sk = sock->sk;
	struct pn_sock *pn = pn_sk(sk);
	struct sockaddr_pn *spn = (struct sockaddr_pn *)addr;
	struct task_struct *tsk = current;
	long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
	int err;

	if (pn_socket_autobind(sock))
		return -ENOBUFS;
	if (len < sizeof(struct sockaddr_pn))
		return -EINVAL;
	if (spn->spn_family != AF_PHONET)
		return -EAFNOSUPPORT;

	lock_sock(sk);

	switch (sock->state) {
	case SS_UNCONNECTED:
		if (sk->sk_state != TCP_CLOSE) {
			err = -EISCONN;
			goto out;
		}
		break;
	case SS_CONNECTING:
		err = -EALREADY;
		goto out;
	default:
		err = -EISCONN;
		goto out;
	}

	pn->dobject = pn_sockaddr_get_object(spn);
	pn->resource = pn_sockaddr_get_resource(spn);
	sock->state = SS_CONNECTING;

	err = sk->sk_prot->connect(sk, addr, len);
	if (err) {
		sock->state = SS_UNCONNECTED;
		pn->dobject = 0;
		goto out;
	}

	while (sk->sk_state == TCP_SYN_SENT) {
		DEFINE_WAIT(wait);

		if (!timeo) {
			err = -EINPROGRESS;
			goto out;
		}
		if (signal_pending(tsk)) {
			err = sock_intr_errno(timeo);
			goto out;
		}

		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
						TASK_INTERRUPTIBLE);
		release_sock(sk);
		timeo = schedule_timeout(timeo);
		lock_sock(sk);
		finish_wait(sk_sleep(sk), &wait);
	}

	if ((1 << sk->sk_state) & (TCPF_SYN_RECV|TCPF_ESTABLISHED))
		err = 0;
	else if (sk->sk_state == TCP_CLOSE_WAIT)
		err = -ECONNRESET;
	else
		err = -ECONNREFUSED;
	sock->state = err ? SS_UNCONNECTED : SS_CONNECTED;
out:
	release_sock(sk);
	return err;
}

static int pn_socket_accept(struct socket *sock, struct socket *newsock,
			    int flags, bool kern)
{
	struct sock *sk = sock->sk;
	struct sock *newsk;
	int err;

	if (unlikely(sk->sk_state != TCP_LISTEN))
		return -EINVAL;

	newsk = sk->sk_prot->accept(sk, flags, &err, kern);
	if (!newsk)
		return err;

	lock_sock(newsk);
	sock_graft(newsk, newsock);
	newsock->state = SS_CONNECTED;
	release_sock(newsk);
	return 0;
}

static int pn_socket_getname(struct socket *sock, struct sockaddr *addr,
				int peer)
{
	struct sock *sk = sock->sk;
	struct pn_sock *pn = pn_sk(sk);

	memset(addr, 0, sizeof(struct sockaddr_pn));
	addr->sa_family = AF_PHONET;
	if (!peer) /* Race with bind() here is userland's problem. */
		pn_sockaddr_set_object((struct sockaddr_pn *)addr,
					pn->sobject);

	return sizeof(struct sockaddr_pn);
}

static __poll_t pn_socket_poll(struct file *file, struct socket *sock,
					poll_table *wait)
{
	struct sock *sk = sock->sk;
	struct pep_sock *pn = pep_sk(sk);
	__poll_t mask = 0;

	poll_wait(file, sk_sleep(sk), wait);

	if (sk->sk_state == TCP_CLOSE)
		return EPOLLERR;
	if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
		mask |= EPOLLIN | EPOLLRDNORM;
	if (!skb_queue_empty_lockless(&pn->ctrlreq_queue))
		mask |= EPOLLPRI;
	if (!mask && sk->sk_state == TCP_CLOSE_WAIT)
		return EPOLLHUP;

	if (sk->sk_state == TCP_ESTABLISHED &&
		refcount_read(&sk->sk_wmem_alloc) < sk->sk_sndbuf &&
		atomic_read(&pn->tx_credits))
		mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;

	return mask;
}

static int pn_socket_ioctl(struct socket *sock, unsigned int cmd,
				unsigned long arg)
{
	struct sock *sk = sock->sk;
	struct pn_sock *pn = pn_sk(sk);

	if (cmd == SIOCPNGETOBJECT) {
		struct net_device *dev;
		u16 handle;
		u8 saddr;

		if (get_user(handle, (__u16 __user *)arg))
			return -EFAULT;

		lock_sock(sk);
		if (sk->sk_bound_dev_if)
			dev = dev_get_by_index(sock_net(sk),
						sk->sk_bound_dev_if);
		else
			dev = phonet_device_get(sock_net(sk));
		if (dev && (dev->flags & IFF_UP))
			saddr = phonet_address_get(dev, pn_addr(handle));
		else
			saddr = PN_NO_ADDR;
		release_sock(sk);

		if (dev)
			dev_put(dev);
		if (saddr == PN_NO_ADDR)
			return -EHOSTUNREACH;

		handle = pn_object(saddr, pn_port(pn->sobject));
		return put_user(handle, (__u16 __user *)arg);
	}

	return sk->sk_prot->ioctl(sk, cmd, arg);
}

static int pn_socket_listen(struct socket *sock, int backlog)
{
	struct sock *sk = sock->sk;
	int err = 0;

	if (pn_socket_autobind(sock))
		return -ENOBUFS;

	lock_sock(sk);
	if (sock->state != SS_UNCONNECTED) {
		err = -EINVAL;
		goto out;
	}

	if (sk->sk_state != TCP_LISTEN) {
		sk->sk_state = TCP_LISTEN;
		sk->sk_ack_backlog = 0;
	}
	sk->sk_max_ack_backlog = backlog;
out:
	release_sock(sk);
	return err;
}

static int pn_socket_sendmsg(struct socket *sock, struct msghdr *m,
			     size_t total_len)
{
	struct sock *sk = sock->sk;

	if (pn_socket_autobind(sock))
		return -EAGAIN;

	return sk->sk_prot->sendmsg(sk, m, total_len);
}

const struct proto_ops phonet_dgram_ops = {
	.family		= AF_PHONET,
	.owner		= THIS_MODULE,
	.release	= pn_socket_release,
	.bind		= pn_socket_bind,
	.connect	= sock_no_connect,
	.socketpair	= sock_no_socketpair,
	.accept		= sock_no_accept,
	.getname	= pn_socket_getname,
	.poll		= datagram_poll,
	.ioctl		= pn_socket_ioctl,
	.listen		= sock_no_listen,
	.shutdown	= sock_no_shutdown,
	.setsockopt	= sock_no_setsockopt,
	.getsockopt	= sock_no_getsockopt,
#ifdef CONFIG_COMPAT
	.compat_setsockopt = sock_no_setsockopt,
	.compat_getsockopt = sock_no_getsockopt,
#endif
	.sendmsg	= pn_socket_sendmsg,
	.recvmsg	= sock_common_recvmsg,
	.mmap		= sock_no_mmap,
	.sendpage	= sock_no_sendpage,
};

const struct proto_ops phonet_stream_ops = {
	.family		= AF_PHONET,
	.owner		= THIS_MODULE,
	.release	= pn_socket_release,
	.bind		= pn_socket_bind,
	.connect	= pn_socket_connect,
	.socketpair	= sock_no_socketpair,
	.accept		= pn_socket_accept,
	.getname	= pn_socket_getname,
	.poll		= pn_socket_poll,
	.ioctl		= pn_socket_ioctl,
	.listen		= pn_socket_listen,
	.shutdown	= sock_no_shutdown,
	.setsockopt	= sock_common_setsockopt,
	.getsockopt	= sock_common_getsockopt,
#ifdef CONFIG_COMPAT
	.compat_setsockopt = compat_sock_common_setsockopt,
	.compat_getsockopt = compat_sock_common_getsockopt,
#endif
	.sendmsg	= pn_socket_sendmsg,
	.recvmsg	= sock_common_recvmsg,
	.mmap		= sock_no_mmap,
	.sendpage	= sock_no_sendpage,
};
EXPORT_SYMBOL(phonet_stream_ops);

/* allocate port for a socket */
int pn_sock_get_port(struct sock *sk, unsigned short sport)
{
	static int port_cur;
	struct net *net = sock_net(sk);
	struct pn_sock *pn = pn_sk(sk);
	struct sockaddr_pn try_sa;
	struct sock *tmpsk;

	memset(&try_sa, 0, sizeof(struct sockaddr_pn));
	try_sa.spn_family = AF_PHONET;
	WARN_ON(!mutex_is_locked(&port_mutex));
	if (!sport) {
		/* search free port */
		int port, pmin, pmax;

		phonet_get_local_port_range(&pmin, &pmax);
		for (port = pmin; port <= pmax; port++) {
			port_cur++;
			if (port_cur < pmin || port_cur > pmax)
				port_cur = pmin;

			pn_sockaddr_set_port(&try_sa, port_cur);
			tmpsk = pn_find_sock_by_sa(net, &try_sa);
			if (tmpsk == NULL) {
				sport = port_cur;
				goto found;
			} else
				sock_put(tmpsk);
		}
	} else {
		/* try to find specific port */
		pn_sockaddr_set_port(&try_sa, sport);
		tmpsk = pn_find_sock_by_sa(net, &try_sa);
		if (tmpsk == NULL)
			/* No sock there! We can use that port... */
			goto found;
		else
			sock_put(tmpsk);
	}
	/* the port must be in use already */
	return -EADDRINUSE;

found:
	pn->sobject = pn_object(pn_addr(pn->sobject), sport);
	return 0;
}
EXPORT_SYMBOL(pn_sock_get_port);

#ifdef CONFIG_PROC_FS
static struct sock *pn_sock_get_idx(struct seq_file *seq, loff_t pos)
{
	struct net *net = seq_file_net(seq);
	struct hlist_head *hlist = pnsocks.hlist;
	struct sock *sknode;
	unsigned int h;

	for (h = 0; h < PN_HASHSIZE; h++) {
		sk_for_each_rcu(sknode, hlist) {
			if (!net_eq(net, sock_net(sknode)))
				continue;
			if (!pos)
				return sknode;
			pos--;
		}
		hlist++;
	}
	return NULL;
}

static struct sock *pn_sock_get_next(struct seq_file *seq, struct sock *sk)
{
	struct net *net = seq_file_net(seq);

	do
		sk = sk_next(sk);
	while (sk && !net_eq(net, sock_net(sk)));

	return sk;
}

static void *pn_sock_seq_start(struct seq_file *seq, loff_t *pos)
	__acquires(rcu)
{
	rcu_read_lock();
	return *pos ? pn_sock_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *pn_sock_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct sock *sk;

	if (v == SEQ_START_TOKEN)
		sk = pn_sock_get_idx(seq, 0);
	else
		sk = pn_sock_get_next(seq, v);
	(*pos)++;
	return sk;
}

static void pn_sock_seq_stop(struct seq_file *seq, void *v)
	__releases(rcu)
{
	rcu_read_unlock();
}

static int pn_sock_seq_show(struct seq_file *seq, void *v)
{
	seq_setwidth(seq, 127);
	if (v == SEQ_START_TOKEN)
		seq_puts(seq, "pt  loc  rem rs st tx_queue rx_queue "
			"  uid inode ref pointer drops");
	else {
		struct sock *sk = v;
		struct pn_sock *pn = pn_sk(sk);

		seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
			"%d %pK %u",
			sk->sk_protocol, pn->sobject, pn->dobject,
			pn->resource, sk->sk_state,
			sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),
			from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
			sock_i_ino(sk),
			refcount_read(&sk->sk_refcnt), sk,
			atomic_read(&sk->sk_drops));
	}
	seq_pad(seq, '\n');
	return 0;
}

const struct seq_operations pn_sock_seq_ops = {
	.start = pn_sock_seq_start,
	.next = pn_sock_seq_next,
	.stop = pn_sock_seq_stop,
	.show = pn_sock_seq_show,
};
#endif

static struct  {
	struct sock *sk[256];
} pnres;

/*
 * Find and hold socket based on resource.
 */
struct sock *pn_find_sock_by_res(struct net *net, u8 res)
{
	struct sock *sk;

	if (!net_eq(net, &init_net))
		return NULL;

	rcu_read_lock();
	sk = rcu_dereference(pnres.sk[res]);
	if (sk)
		sock_hold(sk);
	rcu_read_unlock();
	return sk;
}

static DEFINE_MUTEX(resource_mutex);

int pn_sock_bind_res(struct sock *sk, u8 res)
{
	int ret = -EADDRINUSE;

	if (!net_eq(sock_net(sk), &init_net))
		return -ENOIOCTLCMD;
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (pn_socket_autobind(sk->sk_socket))
		return -EAGAIN;

	mutex_lock(&resource_mutex);
	if (pnres.sk[res] == NULL) {
		sock_hold(sk);
		rcu_assign_pointer(pnres.sk[res], sk);
		ret = 0;
	}
	mutex_unlock(&resource_mutex);
	return ret;
}

int pn_sock_unbind_res(struct sock *sk, u8 res)
{
	int ret = -ENOENT;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	mutex_lock(&resource_mutex);
	if (pnres.sk[res] == sk) {
		RCU_INIT_POINTER(pnres.sk[res], NULL);
		ret = 0;
	}
	mutex_unlock(&resource_mutex);

	if (ret == 0) {
		synchronize_rcu();
		sock_put(sk);
	}
	return ret;
}

void pn_sock_unbind_all_res(struct sock *sk)
{
	unsigned int res, match = 0;

	mutex_lock(&resource_mutex);
	for (res = 0; res < 256; res++) {
		if (pnres.sk[res] == sk) {
			RCU_INIT_POINTER(pnres.sk[res], NULL);
			match++;
		}
	}
	mutex_unlock(&resource_mutex);

	while (match > 0) {
		__sock_put(sk);
		match--;
	}
	/* Caller is responsible for RCU sync before final sock_put() */
}

#ifdef CONFIG_PROC_FS
static struct sock **pn_res_get_idx(struct seq_file *seq, loff_t pos)
{
	struct net *net = seq_file_net(seq);
	unsigned int i;

	if (!net_eq(net, &init_net))
		return NULL;

	for (i = 0; i < 256; i++) {
		if (pnres.sk[i] == NULL)
			continue;
		if (!pos)
			return pnres.sk + i;
		pos--;
	}
	return NULL;
}

static struct sock **pn_res_get_next(struct seq_file *seq, struct sock **sk)
{
	struct net *net = seq_file_net(seq);
	unsigned int i;

	BUG_ON(!net_eq(net, &init_net));

	for (i = (sk - pnres.sk) + 1; i < 256; i++)
		if (pnres.sk[i])
			return pnres.sk + i;
	return NULL;
}

static void *pn_res_seq_start(struct seq_file *seq, loff_t *pos)
	__acquires(resource_mutex)
{
	mutex_lock(&resource_mutex);
	return *pos ? pn_res_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
}

static void *pn_res_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	struct sock **sk;

	if (v == SEQ_START_TOKEN)
		sk = pn_res_get_idx(seq, 0);
	else
		sk = pn_res_get_next(seq, v);
	(*pos)++;
	return sk;
}

static void pn_res_seq_stop(struct seq_file *seq, void *v)
	__releases(resource_mutex)
{
	mutex_unlock(&resource_mutex);
}

static int pn_res_seq_show(struct seq_file *seq, void *v)
{
	seq_setwidth(seq, 63);
	if (v == SEQ_START_TOKEN)
		seq_puts(seq, "rs   uid inode");
	else {
		struct sock **psk = v;
		struct sock *sk = *psk;

		seq_printf(seq, "%02X %5u %lu",
			   (int) (psk - pnres.sk),
			   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk)),
			   sock_i_ino(sk));
	}
	seq_pad(seq, '\n');
	return 0;
}

const struct seq_operations pn_res_seq_ops = {
	.start = pn_res_seq_start,
	.next = pn_res_seq_next,
	.stop = pn_res_seq_stop,
	.show = pn_res_seq_show,
};
#endif