dev-ioctl.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright 2008 Red Hat, Inc. All rights reserved.
  4 * Copyright 2008 Ian Kent <raven@themaw.net>
  5 */
  6
  7#include <linux/module.h>
  8#include <linux/miscdevice.h>
  9#include <linux/compat.h>
 10#include <linux/fdtable.h>
 11#include <linux/magic.h>
 12#include <linux/nospec.h>
 13
 14#include "autofs_i.h"
 15
 16/*
 17 * This module implements an interface for routing autofs ioctl control
 18 * commands via a miscellaneous device file.
 19 *
 20 * The alternate interface is needed because we need to be able open
 21 * an ioctl file descriptor on an autofs mount that may be covered by
 22 * another mount. This situation arises when starting automount(8)
 23 * or other user space daemon which uses direct mounts or offset
 24 * mounts (used for autofs lazy mount/umount of nested mount trees),
 25 * which have been left busy at service shutdown.
 26 */
 27
 28typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
 29			struct autofs_dev_ioctl *);
 30
 31static int check_name(const char *name)
 32{
 33	if (!strchr(name, '/'))
 34		return -EINVAL;
 35	return 0;
 36}
 37
 38/*
 39 * Check a string doesn't overrun the chunk of
 40 * memory we copied from user land.
 41 */
 42static int invalid_str(char *str, size_t size)
 43{
 44	if (memchr(str, 0, size))
 45		return 0;
 46	return -EINVAL;
 47}
 48
 49/*
 50 * Check that the user compiled against correct version of autofs
 51 * misc device code.
 52 *
 53 * As well as checking the version compatibility this always copies
 54 * the kernel interface version out.
 55 */
 56static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
 57{
 58	int err = 0;
 59
 60	if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
 61	    (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
 62		pr_warn("ioctl control interface version mismatch: "
 63			"kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
 64			AUTOFS_DEV_IOCTL_VERSION_MAJOR,
 65			AUTOFS_DEV_IOCTL_VERSION_MINOR,
 66			param->ver_major, param->ver_minor, cmd);
 67		err = -EINVAL;
 68	}
 69
 70	/* Fill in the kernel version. */
 71	param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 72	param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 73
 74	return err;
 75}
 76
 77/*
 78 * Copy parameter control struct, including a possible path allocated
 79 * at the end of the struct.
 80 */
 81static struct autofs_dev_ioctl *
 82copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
 83{
 84	struct autofs_dev_ioctl tmp, *res;
 85
 86	if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
 87		return ERR_PTR(-EFAULT);
 88
 89	if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
 90		return ERR_PTR(-EINVAL);
 91
 92	if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
 93		return ERR_PTR(-ENAMETOOLONG);
 94
 95	res = memdup_user(in, tmp.size);
 96	if (!IS_ERR(res))
 97		res->size = tmp.size;
 98
 99	return res;
100}
101
102static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
103{
104	kfree(param);
105}
106
107/*
108 * Check sanity of parameter control fields and if a path is present
109 * check that it is terminated and contains at least one "/".
110 */
111static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
112{
113	unsigned int inr = _IOC_NR(cmd);
114	int err;
115
116	err = check_dev_ioctl_version(cmd, param);
117	if (err) {
118		pr_warn("invalid device control module version "
119			"supplied for cmd(0x%08x)\n", cmd);
120		goto out;
121	}
122
123	if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
124		err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
125		if (err) {
126			pr_warn(
127			  "path string terminator missing for cmd(0x%08x)\n",
128			  cmd);
129			goto out;
130		}
131
132		/* Setting the per-dentry expire timeout requires a trailing
133		 * path component, ie. no '/', so invert the logic of the
134		 * check_name() return for AUTOFS_DEV_IOCTL_TIMEOUT_CMD.
135		 */
136		err = check_name(param->path);
137		if (inr == AUTOFS_DEV_IOCTL_TIMEOUT_CMD)
138			err = err ? 0 : -EINVAL;
139		if (err) {
140			pr_warn("invalid path supplied for cmd(0x%08x)\n",
141				cmd);
142			goto out;
143		}
144	} else {
145		if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
146		    inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
147		    inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
148			err = -EINVAL;
149			goto out;
150		}
151	}
152
153	err = 0;
154out:
155	return err;
156}
157
158/* Return autofs dev ioctl version */
159static int autofs_dev_ioctl_version(struct file *fp,
160				    struct autofs_sb_info *sbi,
161				    struct autofs_dev_ioctl *param)
162{
163	/* This should have already been set. */
164	param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
165	param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
166	return 0;
167}
168
169/* Return autofs module protocol version */
170static int autofs_dev_ioctl_protover(struct file *fp,
171				     struct autofs_sb_info *sbi,
172				     struct autofs_dev_ioctl *param)
173{
174	param->protover.version = sbi->version;
175	return 0;
176}
177
178/* Return autofs module protocol sub version */
179static int autofs_dev_ioctl_protosubver(struct file *fp,
180					struct autofs_sb_info *sbi,
181					struct autofs_dev_ioctl *param)
182{
183	param->protosubver.sub_version = sbi->sub_version;
184	return 0;
185}
186
187/* Find the topmost mount satisfying test() */
188static int find_autofs_mount(const char *pathname,
189			     struct path *res,
190			     int test(const struct path *path, void *data),
191			     void *data)
192{
193	struct path path;
194	int err;
195
196	err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
197	if (err)
198		return err;
199	err = -ENOENT;
200	while (path.dentry == path.mnt->mnt_root) {
201		if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
202			if (test(&path, data)) {
203				path_get(&path);
204				*res = path;
205				err = 0;
206				break;
207			}
208		}
209		if (!follow_up(&path))
210			break;
211	}
212	path_put(&path);
213	return err;
214}
215
216static int test_by_dev(const struct path *path, void *p)
217{
218	return path->dentry->d_sb->s_dev == *(dev_t *)p;
219}
220
221static int test_by_type(const struct path *path, void *p)
222{
223	struct autofs_info *ino = autofs_dentry_ino(path->dentry);
224
225	return ino && ino->sbi->type & *(unsigned *)p;
226}
227
228/*
229 * Open a file descriptor on the autofs mount point corresponding
230 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
231 */
232static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
233{
234	struct path path __free(path_put) = {};
235	int err;
236
237	err = find_autofs_mount(name, &path, test_by_dev, &devid);
238	if (err)
239		return err;
240
241	return FD_ADD(O_CLOEXEC, dentry_open(&path, O_RDONLY, current_cred()));
242}
243
244/* Open a file descriptor on an autofs mount point */
245static int autofs_dev_ioctl_openmount(struct file *fp,
246				      struct autofs_sb_info *sbi,
247				      struct autofs_dev_ioctl *param)
248{
249	const char *path;
250	dev_t devid;
251	int err, fd;
252
253	/* param->path has been checked in validate_dev_ioctl() */
254
255	if (!param->openmount.devid)
256		return -EINVAL;
257
258	param->ioctlfd = -1;
259
260	path = param->path;
261	devid = new_decode_dev(param->openmount.devid);
262
263	err = 0;
264	fd = autofs_dev_ioctl_open_mountpoint(path, devid);
265	if (unlikely(fd < 0)) {
266		err = fd;
267		goto out;
268	}
269
270	param->ioctlfd = fd;
271out:
272	return err;
273}
274
275/* Close file descriptor allocated above (user can also use close(2)). */
276static int autofs_dev_ioctl_closemount(struct file *fp,
277				       struct autofs_sb_info *sbi,
278				       struct autofs_dev_ioctl *param)
279{
280	return close_fd(param->ioctlfd);
281}
282
283/*
284 * Send "ready" status for an existing wait (either a mount or an expire
285 * request).
286 */
287static int autofs_dev_ioctl_ready(struct file *fp,
288				  struct autofs_sb_info *sbi,
289				  struct autofs_dev_ioctl *param)
290{
291	autofs_wqt_t token;
292
293	token = (autofs_wqt_t) param->ready.token;
294	return autofs_wait_release(sbi, token, 0);
295}
296
297/*
298 * Send "fail" status for an existing wait (either a mount or an expire
299 * request).
300 */
301static int autofs_dev_ioctl_fail(struct file *fp,
302				 struct autofs_sb_info *sbi,
303				 struct autofs_dev_ioctl *param)
304{
305	autofs_wqt_t token;
306	int status;
307
308	token = (autofs_wqt_t) param->fail.token;
309	status = param->fail.status < 0 ? param->fail.status : -ENOENT;
310	return autofs_wait_release(sbi, token, status);
311}
312
313/*
314 * Set the pipe fd for kernel communication to the daemon.
315 *
316 * Normally this is set at mount using an option but if we
317 * are reconnecting to a busy mount then we need to use this
318 * to tell the autofs mount about the new kernel pipe fd. In
319 * order to protect mounts against incorrectly setting the
320 * pipefd we also require that the autofs mount be catatonic.
321 *
322 * This also sets the process group id used to identify the
323 * controlling process (eg. the owning automount(8) daemon).
324 */
325static int autofs_dev_ioctl_setpipefd(struct file *fp,
326				      struct autofs_sb_info *sbi,
327				      struct autofs_dev_ioctl *param)
328{
329	int pipefd;
330	int err = 0;
331	struct pid *new_pid = NULL;
332
333	if (param->setpipefd.pipefd == -1)
334		return -EINVAL;
335
336	pipefd = param->setpipefd.pipefd;
337
338	mutex_lock(&sbi->wq_mutex);
339	if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
340		mutex_unlock(&sbi->wq_mutex);
341		return -EBUSY;
342	} else {
343		struct file *pipe;
344
345		new_pid = get_task_pid(current, PIDTYPE_PGID);
346
347		if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
348			pr_warn("not allowed to change PID namespace\n");
349			err = -EINVAL;
350			goto out;
351		}
352
353		pipe = fget(pipefd);
354		if (!pipe) {
355			err = -EBADF;
356			goto out;
357		}
358		if (autofs_prepare_pipe(pipe) < 0) {
359			err = -EPIPE;
360			fput(pipe);
361			goto out;
362		}
363		swap(sbi->oz_pgrp, new_pid);
364		sbi->pipefd = pipefd;
365		sbi->pipe = pipe;
366		sbi->mnt_ns_id = to_ns_common(current->nsproxy->mnt_ns)->ns_id;
367		sbi->flags &= ~AUTOFS_SBI_CATATONIC;
368	}
369out:
370	put_pid(new_pid);
371	mutex_unlock(&sbi->wq_mutex);
372	return err;
373}
374
375/*
376 * Make the autofs mount point catatonic, no longer responsive to
377 * mount requests. Also closes the kernel pipe file descriptor.
378 */
379static int autofs_dev_ioctl_catatonic(struct file *fp,
380				      struct autofs_sb_info *sbi,
381				      struct autofs_dev_ioctl *param)
382{
383	autofs_catatonic_mode(sbi);
384	return 0;
385}
386
387/*
388 * Set the autofs mount expire timeout.
389 *
390 * There are two places an expire timeout can be set, in the autofs
391 * super block info. (this is all that's needed for direct and offset
392 * mounts because there's a distinct mount corresponding to each of
393 * these) and per-dentry within within the dentry info. If a per-dentry
394 * timeout is set it will override the expire timeout set in the parent
395 * autofs super block info.
396 *
397 * If setting the autofs super block expire timeout the autofs_dev_ioctl
398 * size field will be equal to the autofs_dev_ioctl structure size. If
399 * setting the per-dentry expire timeout the mount point name is passed
400 * in the autofs_dev_ioctl path field and the size field updated to
401 * reflect this.
402 *
403 * Setting the autofs mount expire timeout sets the timeout in the super
404 * block info. struct. Setting the per-dentry timeout does a little more.
405 * If the timeout is equal to -1 the per-dentry timeout (and flag) is
406 * cleared which reverts to using the super block timeout, otherwise if
407 * timeout is 0 the timeout is set to this value and the flag is left
408 * set which disables expiration for the mount point, lastly the flag
409 * and the timeout are set enabling the dentry to use this timeout.
410 */
411static int autofs_dev_ioctl_timeout(struct file *fp,
412				    struct autofs_sb_info *sbi,
413				    struct autofs_dev_ioctl *param)
414{
415	unsigned long timeout = param->timeout.timeout;
416
417	/* If setting the expire timeout for an individual indirect
418	 * mount point dentry the mount trailing component path is
419	 * placed in param->path and param->size adjusted to account
420	 * for it otherwise param->size it is set to the structure
421	 * size.
422	 */
423	if (param->size == AUTOFS_DEV_IOCTL_SIZE) {
424		param->timeout.timeout = sbi->exp_timeout / HZ;
425		sbi->exp_timeout = timeout * HZ;
426	} else {
427		struct dentry *base = fp->f_path.dentry;
428		int path_len = param->size - AUTOFS_DEV_IOCTL_SIZE - 1;
429		struct dentry *dentry;
430		struct autofs_info *ino;
431
432		if (!autofs_type_indirect(sbi->type))
433			return -EINVAL;
434
435		dentry = try_lookup_noperm(&QSTR_LEN(param->path, path_len),
436					   base);
437		if (IS_ERR_OR_NULL(dentry))
438			return dentry ? PTR_ERR(dentry) : -ENOENT;
439		ino = autofs_dentry_ino(dentry);
440		if (!ino) {
441			dput(dentry);
442			return -ENOENT;
443		}
444
445		if (ino->exp_timeout && ino->flags & AUTOFS_INF_EXPIRE_SET)
446			param->timeout.timeout = ino->exp_timeout / HZ;
447		else
448			param->timeout.timeout = sbi->exp_timeout / HZ;
449
450		if (timeout == -1) {
451			/* Revert to using the super block timeout */
452			ino->flags &= ~AUTOFS_INF_EXPIRE_SET;
453			ino->exp_timeout = 0;
454		} else {
455			/* Set the dentry expire flag and timeout.
456			 *
457			 * If timeout is 0 it will prevent the expire
458			 * of this particular automount.
459			 */
460			ino->flags |= AUTOFS_INF_EXPIRE_SET;
461			ino->exp_timeout = timeout * HZ;
462		}
463
464		/* An expire timeout greater than the superblock timeout
465		 * could be a problem at shutdown but the super block
466		 * timeout itself can change so all we can really do is
467		 * warn the user.
468		 */
469		if (ino->flags & AUTOFS_INF_EXPIRE_SET &&
470		    ino->exp_timeout > sbi->exp_timeout)
471			pr_warn("per-mount expire timeout is greater than "
472				"the parent autofs mount timeout which could "
473				"prevent shutdown\n");
474
475		dput(dentry);
476	}
477
478	return 0;
479}
480
481/*
482 * Return the uid and gid of the last request for the mount
483 *
484 * When reconstructing an autofs mount tree with active mounts
485 * we need to re-connect to mounts that may have used the original
486 * process uid and gid (or string variations of them) for mount
487 * lookups within the map entry.
488 */
489static int autofs_dev_ioctl_requester(struct file *fp,
490				      struct autofs_sb_info *sbi,
491				      struct autofs_dev_ioctl *param)
492{
493	struct autofs_info *ino;
494	struct path path;
495	dev_t devid;
496	int err = -ENOENT;
497
498	/* param->path has been checked in validate_dev_ioctl() */
499
500	devid = sbi->sb->s_dev;
501
502	param->requester.uid = param->requester.gid = -1;
503
504	err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
505	if (err)
506		goto out;
507
508	ino = autofs_dentry_ino(path.dentry);
509	if (ino) {
510		err = 0;
511		autofs_expire_wait(&path, 0);
512		spin_lock(&sbi->fs_lock);
513		param->requester.uid =
514			from_kuid_munged(current_user_ns(), ino->uid);
515		param->requester.gid =
516			from_kgid_munged(current_user_ns(), ino->gid);
517		spin_unlock(&sbi->fs_lock);
518	}
519	path_put(&path);
520out:
521	return err;
522}
523
524/*
525 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
526 * more that can be done.
527 */
528static int autofs_dev_ioctl_expire(struct file *fp,
529				   struct autofs_sb_info *sbi,
530				   struct autofs_dev_ioctl *param)
531{
532	struct vfsmount *mnt;
533	int how;
534
535	how = param->expire.how;
536	mnt = fp->f_path.mnt;
537
538	return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
539}
540
541/* Check if autofs mount point is in use */
542static int autofs_dev_ioctl_askumount(struct file *fp,
543				      struct autofs_sb_info *sbi,
544				      struct autofs_dev_ioctl *param)
545{
546	param->askumount.may_umount = 0;
547	if (may_umount(fp->f_path.mnt))
548		param->askumount.may_umount = 1;
549	return 0;
550}
551
552/*
553 * Check if the given path is a mountpoint.
554 *
555 * If we are supplied with the file descriptor of an autofs
556 * mount we're looking for a specific mount. In this case
557 * the path is considered a mountpoint if it is itself a
558 * mountpoint or contains a mount, such as a multi-mount
559 * without a root mount. In this case we return 1 if the
560 * path is a mount point and the super magic of the covering
561 * mount if there is one or 0 if it isn't a mountpoint.
562 *
563 * If we aren't supplied with a file descriptor then we
564 * lookup the path and check if it is the root of a mount.
565 * If a type is given we are looking for a particular autofs
566 * mount and if we don't find a match we return fail. If the
567 * located path is the root of a mount we return 1 along with
568 * the super magic of the mount or 0 otherwise.
569 *
570 * In both cases the device number (as returned by
571 * new_encode_dev()) is also returned.
572 */
573static int autofs_dev_ioctl_ismountpoint(struct file *fp,
574					 struct autofs_sb_info *sbi,
575					 struct autofs_dev_ioctl *param)
576{
577	struct path path;
578	const char *name;
579	unsigned int type;
580	unsigned int devid, magic;
581	int err = -ENOENT;
582
583	/* param->path has been checked in validate_dev_ioctl() */
584
585	name = param->path;
586	type = param->ismountpoint.in.type;
587
588	param->ismountpoint.out.devid = devid = 0;
589	param->ismountpoint.out.magic = magic = 0;
590
591	if (!fp || param->ioctlfd == -1) {
592		if (autofs_type_any(type))
593			err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
594					&path);
595		else
596			err = find_autofs_mount(name, &path,
597						test_by_type, &type);
598		if (err)
599			goto out;
600		devid = new_encode_dev(path.dentry->d_sb->s_dev);
601		err = 0;
602		if (path.mnt->mnt_root == path.dentry) {
603			err = 1;
604			magic = path.dentry->d_sb->s_magic;
605		}
606	} else {
607		dev_t dev = sbi->sb->s_dev;
608
609		err = find_autofs_mount(name, &path, test_by_dev, &dev);
610		if (err)
611			goto out;
612
613		devid = new_encode_dev(dev);
614
615		err = path_has_submounts(&path);
616
617		if (follow_down_one(&path))
618			magic = path.dentry->d_sb->s_magic;
619	}
620
621	param->ismountpoint.out.devid = devid;
622	param->ismountpoint.out.magic = magic;
623	path_put(&path);
624out:
625	return err;
626}
627
628/*
629 * Our range of ioctl numbers isn't 0 based so we need to shift
630 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
631 * lookup.
632 */
633#define cmd_idx(cmd)	(cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
634
635static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
636{
637	static const ioctl_fn _ioctls[] = {
638		autofs_dev_ioctl_version,
639		autofs_dev_ioctl_protover,
640		autofs_dev_ioctl_protosubver,
641		autofs_dev_ioctl_openmount,
642		autofs_dev_ioctl_closemount,
643		autofs_dev_ioctl_ready,
644		autofs_dev_ioctl_fail,
645		autofs_dev_ioctl_setpipefd,
646		autofs_dev_ioctl_catatonic,
647		autofs_dev_ioctl_timeout,
648		autofs_dev_ioctl_requester,
649		autofs_dev_ioctl_expire,
650		autofs_dev_ioctl_askumount,
651		autofs_dev_ioctl_ismountpoint,
652	};
653	unsigned int idx = cmd_idx(cmd);
654
655	if (idx >= ARRAY_SIZE(_ioctls))
656		return NULL;
657	idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
658	return _ioctls[idx];
659}
660
661/* ioctl dispatcher */
662static int _autofs_dev_ioctl(unsigned int command,
663			     struct autofs_dev_ioctl __user *user)
664{
665	struct autofs_dev_ioctl *param;
666	struct file *fp;
667	struct autofs_sb_info *sbi;
668	unsigned int cmd_first, cmd;
669	ioctl_fn fn = NULL;
670	int err = 0;
671
672	cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
673	cmd = _IOC_NR(command);
674
675	if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
676	    cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
677		return -ENOTTY;
678	}
679
680	/* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
681	 * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
682	 */
683	if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
684	    cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
685	    !capable(CAP_SYS_ADMIN))
686		return -EPERM;
687
688	/* Copy the parameters into kernel space. */
689	param = copy_dev_ioctl(user);
690	if (IS_ERR(param))
691		return PTR_ERR(param);
692
693	err = validate_dev_ioctl(command, param);
694	if (err)
695		goto out;
696
697	fn = lookup_dev_ioctl(cmd);
698	if (!fn) {
699		pr_warn("unknown command 0x%08x\n", command);
700		err = -ENOTTY;
701		goto out;
702	}
703
704	fp = NULL;
705	sbi = NULL;
706
707	/*
708	 * For obvious reasons the openmount can't have a file
709	 * descriptor yet. We don't take a reference to the
710	 * file during close to allow for immediate release,
711	 * and the same for retrieving ioctl version.
712	 */
713	if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
714	    cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
715	    cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
716		struct super_block *sb;
717
718		fp = fget(param->ioctlfd);
719		if (!fp) {
720			if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
721				goto cont;
722			err = -EBADF;
723			goto out;
724		}
725
726		sb = file_inode(fp)->i_sb;
727		if (sb->s_type != &autofs_fs_type) {
728			err = -EINVAL;
729			fput(fp);
730			goto out;
731		}
732		sbi = autofs_sbi(sb);
733
734		/*
735		 * Admin needs to be able to set the mount catatonic in
736		 * order to be able to perform the re-open.
737		 */
738		if (!autofs_oz_mode(sbi) &&
739		    cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
740			err = -EACCES;
741			fput(fp);
742			goto out;
743		}
744	}
745cont:
746	err = fn(fp, sbi, param);
747
748	if (fp)
749		fput(fp);
750	if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
751		err = -EFAULT;
752out:
753	free_dev_ioctl(param);
754	return err;
755}
756
757static long autofs_dev_ioctl(struct file *file, unsigned int command,
758			     unsigned long u)
759{
760	int err;
761
762	err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
763	return (long) err;
764}
765
766#ifdef CONFIG_COMPAT
767static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
768				    unsigned long u)
769{
770	return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
771}
772#else
773#define autofs_dev_ioctl_compat NULL
774#endif
775
776static const struct file_operations _dev_ioctl_fops = {
777	.unlocked_ioctl	 = autofs_dev_ioctl,
778	.compat_ioctl = autofs_dev_ioctl_compat,
779	.owner	 = THIS_MODULE,
780	.llseek = noop_llseek,
781};
782
783static struct miscdevice _autofs_dev_ioctl_misc = {
784	.minor		= AUTOFS_MINOR,
785	.name		= AUTOFS_DEVICE_NAME,
786	.fops		= &_dev_ioctl_fops,
787	.mode           = 0644,
788};
789
790MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
791MODULE_ALIAS("devname:autofs");
792
793/* Register/deregister misc character device */
794int __init autofs_dev_ioctl_init(void)
795{
796	int r;
797
798	r = misc_register(&_autofs_dev_ioctl_misc);
799	if (r) {
800		pr_err("misc_register failed for control device\n");
801		return r;
802	}
803
804	return 0;
805}
806
807void autofs_dev_ioctl_exit(void)
808{
809	misc_deregister(&_autofs_dev_ioctl_misc);
810}