1/*
2 * Copyright 2008 Red Hat, Inc. All rights reserved.
3 * Copyright 2008 Ian Kent <raven@themaw.net>
4 *
5 * This file is part of the Linux kernel and is made available under
6 * the terms of the GNU General Public License, version 2, or at your
7 * option, any later version, incorporated herein by reference.
8 */
9
10#include <linux/module.h>
11#include <linux/vmalloc.h>
12#include <linux/miscdevice.h>
13#include <linux/init.h>
14#include <linux/wait.h>
15#include <linux/namei.h>
16#include <linux/fcntl.h>
17#include <linux/file.h>
18#include <linux/fdtable.h>
19#include <linux/sched.h>
20#include <linux/compat.h>
21#include <linux/syscalls.h>
22#include <linux/magic.h>
23#include <linux/dcache.h>
24#include <linux/uaccess.h>
25#include <linux/slab.h>
26
27#include "autofs_i.h"
28
29/*
30 * This module implements an interface for routing autofs ioctl control
31 * commands via a miscellaneous device file.
32 *
33 * The alternate interface is needed because we need to be able open
34 * an ioctl file descriptor on an autofs mount that may be covered by
35 * another mount. This situation arises when starting automount(8)
36 * or other user space daemon which uses direct mounts or offset
37 * mounts (used for autofs lazy mount/umount of nested mount trees),
38 * which have been left busy at at service shutdown.
39 */
40
41#define AUTOFS_DEV_IOCTL_SIZE	sizeof(struct autofs_dev_ioctl)
42
43typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
44			struct autofs_dev_ioctl *);
45
46static int check_name(const char *name)
47{
48	if (!strchr(name, '/'))
49		return -EINVAL;
50	return 0;
51}
52
53/*
54 * Check a string doesn't overrun the chunk of
55 * memory we copied from user land.
56 */
57static int invalid_str(char *str, size_t size)
58{
59	if (memchr(str, 0, size))
60		return 0;
61	return -EINVAL;
62}
63
64/*
65 * Check that the user compiled against correct version of autofs
66 * misc device code.
67 *
68 * As well as checking the version compatibility this always copies
69 * the kernel interface version out.
70 */
71static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
72{
73	int err = 0;
74
75	if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
76	    (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
77		AUTOFS_WARN("ioctl control interface version mismatch: "
78		     "kernel(%u.%u), user(%u.%u), cmd(%d)",
79		     AUTOFS_DEV_IOCTL_VERSION_MAJOR,
80		     AUTOFS_DEV_IOCTL_VERSION_MINOR,
81		     param->ver_major, param->ver_minor, cmd);
82		err = -EINVAL;
83	}
84
85	/* Fill in the kernel version. */
86	param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
87	param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
88
89	return err;
90}
91
92/*
93 * Copy parameter control struct, including a possible path allocated
94 * at the end of the struct.
95 */
96static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
97{
98	struct autofs_dev_ioctl tmp, *res;
99
100	if (copy_from_user(&tmp, in, sizeof(tmp)))
101		return ERR_PTR(-EFAULT);
102
103	if (tmp.size < sizeof(tmp))
104		return ERR_PTR(-EINVAL);
105
106	if (tmp.size > (PATH_MAX + sizeof(tmp)))
107		return ERR_PTR(-ENAMETOOLONG);
108
109	res = memdup_user(in, tmp.size);
110	if (!IS_ERR(res))
111		res->size = tmp.size;
112
113	return res;
114}
115
116static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
117{
118	kfree(param);
119	return;
120}
121
122/*
123 * Check sanity of parameter control fields and if a path is present
124 * check that it is terminated and contains at least one "/".
125 */
126static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
127{
128	int err;
129
130	err = check_dev_ioctl_version(cmd, param);
131	if (err) {
132		AUTOFS_WARN("invalid device control module version "
133		     "supplied for cmd(0x%08x)", cmd);
134		goto out;
135	}
136
137	if (param->size > sizeof(*param)) {
138		err = invalid_str(param->path, param->size - sizeof(*param));
139		if (err) {
140			AUTOFS_WARN(
141			  "path string terminator missing for cmd(0x%08x)",
142			  cmd);
143			goto out;
144		}
145
146		err = check_name(param->path);
147		if (err) {
148			AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
149				    cmd);
150			goto out;
151		}
152	}
153
154	err = 0;
155out:
156	return err;
157}
158
159/*
160 * Get the autofs super block info struct from the file opened on
161 * the autofs mount point.
162 */
163static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
164{
165	struct autofs_sb_info *sbi = NULL;
166	struct inode *inode;
167
168	if (f) {
169		inode = file_inode(f);
170		sbi = autofs4_sbi(inode->i_sb);
171	}
172	return sbi;
173}
174
175/* Return autofs module protocol version */
176static int autofs_dev_ioctl_protover(struct file *fp,
177				     struct autofs_sb_info *sbi,
178				     struct autofs_dev_ioctl *param)
179{
180	param->protover.version = sbi->version;
181	return 0;
182}
183
184/* Return autofs module protocol sub version */
185static int autofs_dev_ioctl_protosubver(struct file *fp,
186					struct autofs_sb_info *sbi,
187					struct autofs_dev_ioctl *param)
188{
189	param->protosubver.sub_version = sbi->sub_version;
190	return 0;
191}
192
193/* Find the topmost mount satisfying test() */
194static int find_autofs_mount(const char *pathname,
195			     struct path *res,
196			     int test(struct path *path, void *data),
197			     void *data)
198{
199	struct path path;
200	int err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
201	if (err)
202		return err;
203	err = -ENOENT;
204	while (path.dentry == path.mnt->mnt_root) {
205		if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
206			if (test(&path, data)) {
207				path_get(&path);
208				*res = path;
209				err = 0;
210				break;
211			}
212		}
213		if (!follow_up(&path))
214			break;
215	}
216	path_put(&path);
217	return err;
218}
219
220static int test_by_dev(struct path *path, void *p)
221{
222	return path->dentry->d_sb->s_dev == *(dev_t *)p;
223}
224
225static int test_by_type(struct path *path, void *p)
226{
227	struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
228	return ino && ino->sbi->type & *(unsigned *)p;
229}
230
231/*
232 * Open a file descriptor on the autofs mount point corresponding
233 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
234 */
235static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
236{
237	int err, fd;
238
239	fd = get_unused_fd_flags(O_CLOEXEC);
240	if (likely(fd >= 0)) {
241		struct file *filp;
242		struct path path;
243
244		err = find_autofs_mount(name, &path, test_by_dev, &devid);
245		if (err)
246			goto out;
247
248		/*
249		 * Find autofs super block that has the device number
250		 * corresponding to the autofs fs we want to open.
251		 */
252
253		filp = dentry_open(&path, O_RDONLY, current_cred());
254		path_put(&path);
255		if (IS_ERR(filp)) {
256			err = PTR_ERR(filp);
257			goto out;
258		}
259
260		fd_install(fd, filp);
261	}
262
263	return fd;
264
265out:
266	put_unused_fd(fd);
267	return err;
268}
269
270/* Open a file descriptor on an autofs mount point */
271static int autofs_dev_ioctl_openmount(struct file *fp,
272				      struct autofs_sb_info *sbi,
273				      struct autofs_dev_ioctl *param)
274{
275	const char *path;
276	dev_t devid;
277	int err, fd;
278
279	/* param->path has already been checked */
280	if (!param->openmount.devid)
281		return -EINVAL;
282
283	param->ioctlfd = -1;
284
285	path = param->path;
286	devid = new_decode_dev(param->openmount.devid);
287
288	err = 0;
289	fd = autofs_dev_ioctl_open_mountpoint(path, devid);
290	if (unlikely(fd < 0)) {
291		err = fd;
292		goto out;
293	}
294
295	param->ioctlfd = fd;
296out:
297	return err;
298}
299
300/* Close file descriptor allocated above (user can also use close(2)). */
301static int autofs_dev_ioctl_closemount(struct file *fp,
302				       struct autofs_sb_info *sbi,
303				       struct autofs_dev_ioctl *param)
304{
305	return sys_close(param->ioctlfd);
306}
307
308/*
309 * Send "ready" status for an existing wait (either a mount or an expire
310 * request).
311 */
312static int autofs_dev_ioctl_ready(struct file *fp,
313				  struct autofs_sb_info *sbi,
314				  struct autofs_dev_ioctl *param)
315{
316	autofs_wqt_t token;
317
318	token = (autofs_wqt_t) param->ready.token;
319	return autofs4_wait_release(sbi, token, 0);
320}
321
322/*
323 * Send "fail" status for an existing wait (either a mount or an expire
324 * request).
325 */
326static int autofs_dev_ioctl_fail(struct file *fp,
327				 struct autofs_sb_info *sbi,
328				 struct autofs_dev_ioctl *param)
329{
330	autofs_wqt_t token;
331	int status;
332
333	token = (autofs_wqt_t) param->fail.token;
334	status = param->fail.status ? param->fail.status : -ENOENT;
335	return autofs4_wait_release(sbi, token, status);
336}
337
338/*
339 * Set the pipe fd for kernel communication to the daemon.
340 *
341 * Normally this is set at mount using an option but if we
342 * are reconnecting to a busy mount then we need to use this
343 * to tell the autofs mount about the new kernel pipe fd. In
344 * order to protect mounts against incorrectly setting the
345 * pipefd we also require that the autofs mount be catatonic.
346 *
347 * This also sets the process group id used to identify the
348 * controlling process (eg. the owning automount(8) daemon).
349 */
350static int autofs_dev_ioctl_setpipefd(struct file *fp,
351				      struct autofs_sb_info *sbi,
352				      struct autofs_dev_ioctl *param)
353{
354	int pipefd;
355	int err = 0;
356	struct pid *new_pid = NULL;
357
358	if (param->setpipefd.pipefd == -1)
359		return -EINVAL;
360
361	pipefd = param->setpipefd.pipefd;
362
363	mutex_lock(&sbi->wq_mutex);
364	if (!sbi->catatonic) {
365		mutex_unlock(&sbi->wq_mutex);
366		return -EBUSY;
367	} else {
368		struct file *pipe;
369
370		new_pid = get_task_pid(current, PIDTYPE_PGID);
371
372		if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
373			AUTOFS_WARN("Not allowed to change PID namespace");
374			err = -EINVAL;
375			goto out;
376		}
377
378		pipe = fget(pipefd);
379		if (!pipe) {
380			err = -EBADF;
381			goto out;
382		}
383		if (autofs_prepare_pipe(pipe) < 0) {
384			err = -EPIPE;
385			fput(pipe);
386			goto out;
387		}
388		swap(sbi->oz_pgrp, new_pid);
389		sbi->pipefd = pipefd;
390		sbi->pipe = pipe;
391		sbi->catatonic = 0;
392	}
393out:
394	put_pid(new_pid);
395	mutex_unlock(&sbi->wq_mutex);
396	return err;
397}
398
399/*
400 * Make the autofs mount point catatonic, no longer responsive to
401 * mount requests. Also closes the kernel pipe file descriptor.
402 */
403static int autofs_dev_ioctl_catatonic(struct file *fp,
404				      struct autofs_sb_info *sbi,
405				      struct autofs_dev_ioctl *param)
406{
407	autofs4_catatonic_mode(sbi);
408	return 0;
409}
410
411/* Set the autofs mount timeout */
412static int autofs_dev_ioctl_timeout(struct file *fp,
413				    struct autofs_sb_info *sbi,
414				    struct autofs_dev_ioctl *param)
415{
416	unsigned long timeout;
417
418	timeout = param->timeout.timeout;
419	param->timeout.timeout = sbi->exp_timeout / HZ;
420	sbi->exp_timeout = timeout * HZ;
421	return 0;
422}
423
424/*
425 * Return the uid and gid of the last request for the mount
426 *
427 * When reconstructing an autofs mount tree with active mounts
428 * we need to re-connect to mounts that may have used the original
429 * process uid and gid (or string variations of them) for mount
430 * lookups within the map entry.
431 */
432static int autofs_dev_ioctl_requester(struct file *fp,
433				      struct autofs_sb_info *sbi,
434				      struct autofs_dev_ioctl *param)
435{
436	struct autofs_info *ino;
437	struct path path;
438	dev_t devid;
439	int err = -ENOENT;
440
441	if (param->size <= sizeof(*param)) {
442		err = -EINVAL;
443		goto out;
444	}
445
446	devid = sbi->sb->s_dev;
447
448	param->requester.uid = param->requester.gid = -1;
449
450	err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
451	if (err)
452		goto out;
453
454	ino = autofs4_dentry_ino(path.dentry);
455	if (ino) {
456		err = 0;
457		autofs4_expire_wait(path.dentry, 0);
458		spin_lock(&sbi->fs_lock);
459		param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid);
460		param->requester.gid = from_kgid_munged(current_user_ns(), ino->gid);
461		spin_unlock(&sbi->fs_lock);
462	}
463	path_put(&path);
464out:
465	return err;
466}
467
468/*
469 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
470 * more that can be done.
471 */
472static int autofs_dev_ioctl_expire(struct file *fp,
473				   struct autofs_sb_info *sbi,
474				   struct autofs_dev_ioctl *param)
475{
476	struct vfsmount *mnt;
477	int how;
478
479	how = param->expire.how;
480	mnt = fp->f_path.mnt;
481
482	return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
483}
484
485/* Check if autofs mount point is in use */
486static int autofs_dev_ioctl_askumount(struct file *fp,
487				      struct autofs_sb_info *sbi,
488				      struct autofs_dev_ioctl *param)
489{
490	param->askumount.may_umount = 0;
491	if (may_umount(fp->f_path.mnt))
492		param->askumount.may_umount = 1;
493	return 0;
494}
495
496/*
497 * Check if the given path is a mountpoint.
498 *
499 * If we are supplied with the file descriptor of an autofs
500 * mount we're looking for a specific mount. In this case
501 * the path is considered a mountpoint if it is itself a
502 * mountpoint or contains a mount, such as a multi-mount
503 * without a root mount. In this case we return 1 if the
504 * path is a mount point and the super magic of the covering
505 * mount if there is one or 0 if it isn't a mountpoint.
506 *
507 * If we aren't supplied with a file descriptor then we
508 * lookup the path and check if it is the root of a mount.
509 * If a type is given we are looking for a particular autofs
510 * mount and if we don't find a match we return fail. If the
511 * located path is the root of a mount we return 1 along with
512 * the super magic of the mount or 0 otherwise.
513 *
514 * In both cases the the device number (as returned by
515 * new_encode_dev()) is also returned.
516 */
517static int autofs_dev_ioctl_ismountpoint(struct file *fp,
518					 struct autofs_sb_info *sbi,
519					 struct autofs_dev_ioctl *param)
520{
521	struct path path;
522	const char *name;
523	unsigned int type;
524	unsigned int devid, magic;
525	int err = -ENOENT;
526
527	if (param->size <= sizeof(*param)) {
528		err = -EINVAL;
529		goto out;
530	}
531
532	name = param->path;
533	type = param->ismountpoint.in.type;
534
535	param->ismountpoint.out.devid = devid = 0;
536	param->ismountpoint.out.magic = magic = 0;
537
538	if (!fp || param->ioctlfd == -1) {
539		if (autofs_type_any(type))
540			err = kern_path_mountpoint(AT_FDCWD,
541						   name, &path, LOOKUP_FOLLOW);
542		else
543			err = find_autofs_mount(name, &path,
544						test_by_type, &type);
545		if (err)
546			goto out;
547		devid = new_encode_dev(path.dentry->d_sb->s_dev);
548		err = 0;
549		if (path.mnt->mnt_root == path.dentry) {
550			err = 1;
551			magic = path.dentry->d_sb->s_magic;
552		}
553	} else {
554		dev_t dev = sbi->sb->s_dev;
555
556		err = find_autofs_mount(name, &path, test_by_dev, &dev);
557		if (err)
558			goto out;
559
560		devid = new_encode_dev(dev);
561
562		err = have_submounts(path.dentry);
563
564		if (follow_down_one(&path))
565			magic = path.dentry->d_sb->s_magic;
566	}
567
568	param->ismountpoint.out.devid = devid;
569	param->ismountpoint.out.magic = magic;
570	path_put(&path);
571out:
572	return err;
573}
574
575/*
576 * Our range of ioctl numbers isn't 0 based so we need to shift
577 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
578 * lookup.
579 */
580#define cmd_idx(cmd)	(cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
581
582static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
583{
584	static struct {
585		int cmd;
586		ioctl_fn fn;
587	} _ioctls[] = {
588		{cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
589		{cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
590			 autofs_dev_ioctl_protover},
591		{cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
592			 autofs_dev_ioctl_protosubver},
593		{cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
594			 autofs_dev_ioctl_openmount},
595		{cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
596			 autofs_dev_ioctl_closemount},
597		{cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
598			 autofs_dev_ioctl_ready},
599		{cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
600			 autofs_dev_ioctl_fail},
601		{cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
602			 autofs_dev_ioctl_setpipefd},
603		{cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
604			 autofs_dev_ioctl_catatonic},
605		{cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
606			 autofs_dev_ioctl_timeout},
607		{cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
608			 autofs_dev_ioctl_requester},
609		{cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
610			 autofs_dev_ioctl_expire},
611		{cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
612			 autofs_dev_ioctl_askumount},
613		{cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
614			 autofs_dev_ioctl_ismountpoint}
615	};
616	unsigned int idx = cmd_idx(cmd);
617
618	return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
619}
620
621/* ioctl dispatcher */
622static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
623{
624	struct autofs_dev_ioctl *param;
625	struct file *fp;
626	struct autofs_sb_info *sbi;
627	unsigned int cmd_first, cmd;
628	ioctl_fn fn = NULL;
629	int err = 0;
630
631	/* only root can play with this */
632	if (!capable(CAP_SYS_ADMIN))
633		return -EPERM;
634
635	cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
636	cmd = _IOC_NR(command);
637
638	if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
639	    cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
640		return -ENOTTY;
641	}
642
643	/* Copy the parameters into kernel space. */
644	param = copy_dev_ioctl(user);
645	if (IS_ERR(param))
646		return PTR_ERR(param);
647
648	err = validate_dev_ioctl(command, param);
649	if (err)
650		goto out;
651
652	/* The validate routine above always sets the version */
653	if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
654		goto done;
655
656	fn = lookup_dev_ioctl(cmd);
657	if (!fn) {
658		AUTOFS_WARN("unknown command 0x%08x", command);
659		return -ENOTTY;
660	}
661
662	fp = NULL;
663	sbi = NULL;
664
665	/*
666	 * For obvious reasons the openmount can't have a file
667	 * descriptor yet. We don't take a reference to the
668	 * file during close to allow for immediate release.
669	 */
670	if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
671	    cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
672		fp = fget(param->ioctlfd);
673		if (!fp) {
674			if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
675				goto cont;
676			err = -EBADF;
677			goto out;
678		}
679
680		sbi = autofs_dev_ioctl_sbi(fp);
681		if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
682			err = -EINVAL;
683			fput(fp);
684			goto out;
685		}
686
687		/*
688		 * Admin needs to be able to set the mount catatonic in
689		 * order to be able to perform the re-open.
690		 */
691		if (!autofs4_oz_mode(sbi) &&
692		    cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
693			err = -EACCES;
694			fput(fp);
695			goto out;
696		}
697	}
698cont:
699	err = fn(fp, sbi, param);
700
701	if (fp)
702		fput(fp);
703done:
704	if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
705		err = -EFAULT;
706out:
707	free_dev_ioctl(param);
708	return err;
709}
710
711static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
712{
713	int err;
714	err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
715	return (long) err;
716}
717
718#ifdef CONFIG_COMPAT
719static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
720{
721	return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
722}
723#else
724#define autofs_dev_ioctl_compat NULL
725#endif
726
727static const struct file_operations _dev_ioctl_fops = {
728	.unlocked_ioctl	 = autofs_dev_ioctl,
729	.compat_ioctl = autofs_dev_ioctl_compat,
730	.owner	 = THIS_MODULE,
731	.llseek = noop_llseek,
732};
733
734static struct miscdevice _autofs_dev_ioctl_misc = {
735	.minor		= AUTOFS_MINOR,
736	.name  		= AUTOFS_DEVICE_NAME,
737	.fops  		= &_dev_ioctl_fops
738};
739
740MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
741MODULE_ALIAS("devname:autofs");
742
743/* Register/deregister misc character device */
744int __init autofs_dev_ioctl_init(void)
745{
746	int r;
747
748	r = misc_register(&_autofs_dev_ioctl_misc);
749	if (r) {
750		AUTOFS_ERROR("misc_register failed for control device");
751		return r;
752	}
753
754	return 0;
755}
756
757void autofs_dev_ioctl_exit(void)
758{
759	misc_deregister(&_autofs_dev_ioctl_misc);
760	return;
761}
762
763