summaryrefslogtreecommitdiff
path: root/fs/autofs/dev-ioctl.c
blob: a2281ab2b957421d48d369411da0c488d893982b (plain)
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
/*
 * Copyright 2008 Red Hat, Inc. All rights reserved.
 * Copyright 2008 Ian Kent <raven@themaw.net>
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 */

#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/namei.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/magic.h>
#include <linux/dcache.h>
#include <linux/uaccess.h>
#include <linux/slab.h>

#include "autofs_i.h"

/*
 * This module implements an interface for routing autofs ioctl control
 * commands via a miscellaneous device file.
 *
 * The alternate interface is needed because we need to be able open
 * an ioctl file descriptor on an autofs mount that may be covered by
 * another mount. This situation arises when starting automount(8)
 * or other user space daemon which uses direct mounts or offset
 * mounts (used for autofs lazy mount/umount of nested mount trees),
 * which have been left busy at at service shutdown.
 */

typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
			struct autofs_dev_ioctl *);

static int check_name(const char *name)
{
	if (!strchr(name, '/'))
		return -EINVAL;
	return 0;
}

/*
 * Check a string doesn't overrun the chunk of
 * memory we copied from user land.
 */
static int invalid_str(char *str, size_t size)
{
	if (memchr(str, 0, size))
		return 0;
	return -EINVAL;
}

/*
 * Check that the user compiled against correct version of autofs
 * misc device code.
 *
 * As well as checking the version compatibility this always copies
 * the kernel interface version out.
 */
static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
{
	int err = 0;

	if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
	    (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
		pr_warn("ioctl control interface version mismatch: "
			"kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
			AUTOFS_DEV_IOCTL_VERSION_MAJOR,
			AUTOFS_DEV_IOCTL_VERSION_MINOR,
			param->ver_major, param->ver_minor, cmd);
		err = -EINVAL;
	}

	/* Fill in the kernel version. */
	param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
	param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;

	return err;
}

/*
 * Copy parameter control struct, including a possible path allocated
 * at the end of the struct.
 */
static struct autofs_dev_ioctl *
copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
{
	struct autofs_dev_ioctl tmp, *res;

	if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
		return ERR_PTR(-EFAULT);

	if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
		return ERR_PTR(-EINVAL);

	if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
		return ERR_PTR(-ENAMETOOLONG);

	res = memdup_user(in, tmp.size);
	if (!IS_ERR(res))
		res->size = tmp.size;

	return res;
}

static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
{
	kfree(param);
}

/*
 * Check sanity of parameter control fields and if a path is present
 * check that it is terminated and contains at least one "/".
 */
static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
{
	int err;

	err = check_dev_ioctl_version(cmd, param);
	if (err) {
		pr_warn("invalid device control module version "
			"supplied for cmd(0x%08x)\n", cmd);
		goto out;
	}

	if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
		err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
		if (err) {
			pr_warn(
			  "path string terminator missing for cmd(0x%08x)\n",
			  cmd);
			goto out;
		}

		err = check_name(param->path);
		if (err) {
			pr_warn("invalid path supplied for cmd(0x%08x)\n",
				cmd);
			goto out;
		}
	}

	err = 0;
out:
	return err;
}

/*
 * Get the autofs super block info struct from the file opened on
 * the autofs mount point.
 */
static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
{
	struct autofs_sb_info *sbi = NULL;
	struct inode *inode;

	if (f) {
		inode = file_inode(f);
		sbi = autofs_sbi(inode->i_sb);
	}
	return sbi;
}

/* Return autofs dev ioctl version */
static int autofs_dev_ioctl_version(struct file *fp,
				    struct autofs_sb_info *sbi,
				    struct autofs_dev_ioctl *param)
{
	/* This should have already been set. */
	param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
	param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
	return 0;
}

/* Return autofs module protocol version */
static int autofs_dev_ioctl_protover(struct file *fp,
				     struct autofs_sb_info *sbi,
				     struct autofs_dev_ioctl *param)
{
	param->protover.version = sbi->version;
	return 0;
}

/* Return autofs module protocol sub version */
static int autofs_dev_ioctl_protosubver(struct file *fp,
					struct autofs_sb_info *sbi,
					struct autofs_dev_ioctl *param)
{
	param->protosubver.sub_version = sbi->sub_version;
	return 0;
}

/* Find the topmost mount satisfying test() */
static int find_autofs_mount(const char *pathname,
			     struct path *res,
			     int test(const struct path *path, void *data),
			     void *data)
{
	struct path path;
	int err;

	err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
	if (err)
		return err;
	err = -ENOENT;
	while (path.dentry == path.mnt->mnt_root) {
		if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
			if (test(&path, data)) {
				path_get(&path);
				*res = path;
				err = 0;
				break;
			}
		}
		if (!follow_up(&path))
			break;
	}
	path_put(&path);
	return err;
}

static int test_by_dev(const struct path *path, void *p)
{
	return path->dentry->d_sb->s_dev == *(dev_t *)p;
}

static int test_by_type(const struct path *path, void *p)
{
	struct autofs_info *ino = autofs_dentry_ino(path->dentry);

	return ino && ino->sbi->type & *(unsigned *)p;
}

/*
 * Open a file descriptor on the autofs mount point corresponding
 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 */
static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
{
	int err, fd;

	fd = get_unused_fd_flags(O_CLOEXEC);
	if (likely(fd >= 0)) {
		struct file *filp;
		struct path path;

		err = find_autofs_mount(name, &path, test_by_dev, &devid);
		if (err)
			goto out;

		filp = dentry_open(&path, O_RDONLY, current_cred());
		path_put(&path);
		if (IS_ERR(filp)) {
			err = PTR_ERR(filp);
			goto out;
		}

		fd_install(fd, filp);
	}

	return fd;

out:
	put_unused_fd(fd);
	return err;
}

/* Open a file descriptor on an autofs mount point */
static int autofs_dev_ioctl_openmount(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	const char *path;
	dev_t devid;
	int err, fd;

	/* param->path has already been checked */
	if (!param->openmount.devid)
		return -EINVAL;

	param->ioctlfd = -1;

	path = param->path;
	devid = new_decode_dev(param->openmount.devid);

	err = 0;
	fd = autofs_dev_ioctl_open_mountpoint(path, devid);
	if (unlikely(fd < 0)) {
		err = fd;
		goto out;
	}

	param->ioctlfd = fd;
out:
	return err;
}

/* Close file descriptor allocated above (user can also use close(2)). */
static int autofs_dev_ioctl_closemount(struct file *fp,
				       struct autofs_sb_info *sbi,
				       struct autofs_dev_ioctl *param)
{
	return ksys_close(param->ioctlfd);
}

/*
 * Send "ready" status for an existing wait (either a mount or an expire
 * request).
 */
static int autofs_dev_ioctl_ready(struct file *fp,
				  struct autofs_sb_info *sbi,
				  struct autofs_dev_ioctl *param)
{
	autofs_wqt_t token;

	token = (autofs_wqt_t) param->ready.token;
	return autofs_wait_release(sbi, token, 0);
}

/*
 * Send "fail" status for an existing wait (either a mount or an expire
 * request).
 */
static int autofs_dev_ioctl_fail(struct file *fp,
				 struct autofs_sb_info *sbi,
				 struct autofs_dev_ioctl *param)
{
	autofs_wqt_t token;
	int status;

	token = (autofs_wqt_t) param->fail.token;
	status = param->fail.status < 0 ? param->fail.status : -ENOENT;
	return autofs_wait_release(sbi, token, status);
}

/*
 * Set the pipe fd for kernel communication to the daemon.
 *
 * Normally this is set at mount using an option but if we
 * are reconnecting to a busy mount then we need to use this
 * to tell the autofs mount about the new kernel pipe fd. In
 * order to protect mounts against incorrectly setting the
 * pipefd we also require that the autofs mount be catatonic.
 *
 * This also sets the process group id used to identify the
 * controlling process (eg. the owning automount(8) daemon).
 */
static int autofs_dev_ioctl_setpipefd(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	int pipefd;
	int err = 0;
	struct pid *new_pid = NULL;

	if (param->setpipefd.pipefd == -1)
		return -EINVAL;

	pipefd = param->setpipefd.pipefd;

	mutex_lock(&sbi->wq_mutex);
	if (!sbi->catatonic) {
		mutex_unlock(&sbi->wq_mutex);
		return -EBUSY;
	} else {
		struct file *pipe;

		new_pid = get_task_pid(current, PIDTYPE_PGID);

		if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
			pr_warn("not allowed to change PID namespace\n");
			err = -EINVAL;
			goto out;
		}

		pipe = fget(pipefd);
		if (!pipe) {
			err = -EBADF;
			goto out;
		}
		if (autofs_prepare_pipe(pipe) < 0) {
			err = -EPIPE;
			fput(pipe);
			goto out;
		}
		swap(sbi->oz_pgrp, new_pid);
		sbi->pipefd = pipefd;
		sbi->pipe = pipe;
		sbi->catatonic = 0;
	}
out:
	put_pid(new_pid);
	mutex_unlock(&sbi->wq_mutex);
	return err;
}

/*
 * Make the autofs mount point catatonic, no longer responsive to
 * mount requests. Also closes the kernel pipe file descriptor.
 */
static int autofs_dev_ioctl_catatonic(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	autofs_catatonic_mode(sbi);
	return 0;
}

/* Set the autofs mount timeout */
static int autofs_dev_ioctl_timeout(struct file *fp,
				    struct autofs_sb_info *sbi,
				    struct autofs_dev_ioctl *param)
{
	unsigned long timeout;

	timeout = param->timeout.timeout;
	param->timeout.timeout = sbi->exp_timeout / HZ;
	sbi->exp_timeout = timeout * HZ;
	return 0;
}

/*
 * Return the uid and gid of the last request for the mount
 *
 * When reconstructing an autofs mount tree with active mounts
 * we need to re-connect to mounts that may have used the original
 * process uid and gid (or string variations of them) for mount
 * lookups within the map entry.
 */
static int autofs_dev_ioctl_requester(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	struct autofs_info *ino;
	struct path path;
	dev_t devid;
	int err = -ENOENT;

	if (param->size <= AUTOFS_DEV_IOCTL_SIZE) {
		err = -EINVAL;
		goto out;
	}

	devid = sbi->sb->s_dev;

	param->requester.uid = param->requester.gid = -1;

	err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
	if (err)
		goto out;

	ino = autofs_dentry_ino(path.dentry);
	if (ino) {
		err = 0;
		autofs_expire_wait(&path, 0);
		spin_lock(&sbi->fs_lock);
		param->requester.uid =
			from_kuid_munged(current_user_ns(), ino->uid);
		param->requester.gid =
			from_kgid_munged(current_user_ns(), ino->gid);
		spin_unlock(&sbi->fs_lock);
	}
	path_put(&path);
out:
	return err;
}

/*
 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 * more that can be done.
 */
static int autofs_dev_ioctl_expire(struct file *fp,
				   struct autofs_sb_info *sbi,
				   struct autofs_dev_ioctl *param)
{
	struct vfsmount *mnt;
	int how;

	how = param->expire.how;
	mnt = fp->f_path.mnt;

	return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
}

/* Check if autofs mount point is in use */
static int autofs_dev_ioctl_askumount(struct file *fp,
				      struct autofs_sb_info *sbi,
				      struct autofs_dev_ioctl *param)
{
	param->askumount.may_umount = 0;
	if (may_umount(fp->f_path.mnt))
		param->askumount.may_umount = 1;
	return 0;
}

/*
 * Check if the given path is a mountpoint.
 *
 * If we are supplied with the file descriptor of an autofs
 * mount we're looking for a specific mount. In this case
 * the path is considered a mountpoint if it is itself a
 * mountpoint or contains a mount, such as a multi-mount
 * without a root mount. In this case we return 1 if the
 * path is a mount point and the super magic of the covering
 * mount if there is one or 0 if it isn't a mountpoint.
 *
 * If we aren't supplied with a file descriptor then we
 * lookup the path and check if it is the root of a mount.
 * If a type is given we are looking for a particular autofs
 * mount and if we don't find a match we return fail. If the
 * located path is the root of a mount we return 1 along with
 * the super magic of the mount or 0 otherwise.
 *
 * In both cases the the device number (as returned by
 * new_encode_dev()) is also returned.
 */
static int autofs_dev_ioctl_ismountpoint(struct file *fp,
					 struct autofs_sb_info *sbi,
					 struct autofs_dev_ioctl *param)
{
	struct path path;
	const char *name;
	unsigned int type;
	unsigned int devid, magic;
	int err = -ENOENT;

	if (param->size <= AUTOFS_DEV_IOCTL_SIZE) {
		err = -EINVAL;
		goto out;
	}

	name = param->path;
	type = param->ismountpoint.in.type;

	param->ismountpoint.out.devid = devid = 0;
	param->ismountpoint.out.magic = magic = 0;

	if (!fp || param->ioctlfd == -1) {
		if (autofs_type_any(type))
			err = kern_path_mountpoint(AT_FDCWD,
						   name, &path, LOOKUP_FOLLOW);
		else
			err = find_autofs_mount(name, &path,
						test_by_type, &type);
		if (err)
			goto out;
		devid = new_encode_dev(path.dentry->d_sb->s_dev);
		err = 0;
		if (path.mnt->mnt_root == path.dentry) {
			err = 1;
			magic = path.dentry->d_sb->s_magic;
		}
	} else {
		dev_t dev = sbi->sb->s_dev;

		err = find_autofs_mount(name, &path, test_by_dev, &dev);
		if (err)
			goto out;

		devid = new_encode_dev(dev);

		err = path_has_submounts(&path);

		if (follow_down_one(&path))
			magic = path.dentry->d_sb->s_magic;
	}

	param->ismountpoint.out.devid = devid;
	param->ismountpoint.out.magic = magic;
	path_put(&path);
out:
	return err;
}

/*
 * Our range of ioctl numbers isn't 0 based so we need to shift
 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 * lookup.
 */
#define cmd_idx(cmd)	(cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))

static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
{
	static ioctl_fn _ioctls[] = {
		autofs_dev_ioctl_version,
		autofs_dev_ioctl_protover,
		autofs_dev_ioctl_protosubver,
		autofs_dev_ioctl_openmount,
		autofs_dev_ioctl_closemount,
		autofs_dev_ioctl_ready,
		autofs_dev_ioctl_fail,
		autofs_dev_ioctl_setpipefd,
		autofs_dev_ioctl_catatonic,
		autofs_dev_ioctl_timeout,
		autofs_dev_ioctl_requester,
		autofs_dev_ioctl_expire,
		autofs_dev_ioctl_askumount,
		autofs_dev_ioctl_ismountpoint,
	};
	unsigned int idx = cmd_idx(cmd);

	return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
}

/* ioctl dispatcher */
static int _autofs_dev_ioctl(unsigned int command,
			     struct autofs_dev_ioctl __user *user)
{
	struct autofs_dev_ioctl *param;
	struct file *fp;
	struct autofs_sb_info *sbi;
	unsigned int cmd_first, cmd;
	ioctl_fn fn = NULL;
	int err = 0;

	cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
	cmd = _IOC_NR(command);

	if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
	    cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
		return -ENOTTY;
	}

	/* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
	 * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
	 */
	if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
	    cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
	    !capable(CAP_SYS_ADMIN))
		return -EPERM;

	/* Copy the parameters into kernel space. */
	param = copy_dev_ioctl(user);
	if (IS_ERR(param))
		return PTR_ERR(param);

	err = validate_dev_ioctl(command, param);
	if (err)
		goto out;

	fn = lookup_dev_ioctl(cmd);
	if (!fn) {
		pr_warn("unknown command 0x%08x\n", command);
		err = -ENOTTY;
		goto out;
	}

	fp = NULL;
	sbi = NULL;

	/*
	 * For obvious reasons the openmount can't have a file
	 * descriptor yet. We don't take a reference to the
	 * file during close to allow for immediate release,
	 * and the same for retrieving ioctl version.
	 */
	if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
	    cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
	    cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
		fp = fget(param->ioctlfd);
		if (!fp) {
			if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
				goto cont;
			err = -EBADF;
			goto out;
		}

		sbi = autofs_dev_ioctl_sbi(fp);
		if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
			err = -EINVAL;
			fput(fp);
			goto out;
		}

		/*
		 * Admin needs to be able to set the mount catatonic in
		 * order to be able to perform the re-open.
		 */
		if (!autofs_oz_mode(sbi) &&
		    cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
			err = -EACCES;
			fput(fp);
			goto out;
		}
	}
cont:
	err = fn(fp, sbi, param);

	if (fp)
		fput(fp);
	if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
		err = -EFAULT;
out:
	free_dev_ioctl(param);
	return err;
}

static long autofs_dev_ioctl(struct file *file, unsigned int command,
			     unsigned long u)
{
	int err;

	err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
	return (long) err;
}

#ifdef CONFIG_COMPAT
static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
				    unsigned long u)
{
	return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
}
#else
#define autofs_dev_ioctl_compat NULL
#endif

static const struct file_operations _dev_ioctl_fops = {
	.unlocked_ioctl	 = autofs_dev_ioctl,
	.compat_ioctl = autofs_dev_ioctl_compat,
	.owner	 = THIS_MODULE,
	.llseek = noop_llseek,
};

static struct miscdevice _autofs_dev_ioctl_misc = {
	.minor		= AUTOFS_MINOR,
	.name		= AUTOFS_DEVICE_NAME,
	.fops		= &_dev_ioctl_fops,
	.mode           = 0644,
};

MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
MODULE_ALIAS("devname:autofs");

/* Register/deregister misc character device */
int __init autofs_dev_ioctl_init(void)
{
	int r;

	r = misc_register(&_autofs_dev_ioctl_misc);
	if (r) {
		pr_err("misc_register failed for control device\n");
		return r;
	}

	return 0;
}

void autofs_dev_ioctl_exit(void)
{
	misc_deregister(&_autofs_dev_ioctl_misc);
}