1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
4 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
5 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
6 */
7
8 #include <linux/capability.h>
9 #include <linux/compat.h>
10
11 #include "autofs_i.h"
12
13 static int autofs_dir_symlink(struct inode *, struct dentry *, const char *);
14 static int autofs_dir_unlink(struct inode *, struct dentry *);
15 static int autofs_dir_rmdir(struct inode *, struct dentry *);
16 static int autofs_dir_mkdir(struct inode *, struct dentry *, umode_t);
17 static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
18 #ifdef CONFIG_COMPAT
19 static long autofs_root_compat_ioctl(struct file *,
20 unsigned int, unsigned long);
21 #endif
22 static int autofs_dir_open(struct inode *inode, struct file *file);
23 static struct dentry *autofs_lookup(struct inode *,
24 struct dentry *, unsigned int);
25 static struct vfsmount *autofs_d_automount(struct path *);
26 static int autofs_d_manage(const struct path *, bool);
27 static void autofs_dentry_release(struct dentry *);
28
29 const struct file_operations autofs_root_operations = {
30 .open = dcache_dir_open,
31 .release = dcache_dir_close,
32 .read = generic_read_dir,
33 .iterate_shared = dcache_readdir,
34 .llseek = dcache_dir_lseek,
35 .unlocked_ioctl = autofs_root_ioctl,
36 #ifdef CONFIG_COMPAT
37 .compat_ioctl = autofs_root_compat_ioctl,
38 #endif
39 };
40
41 const struct file_operations autofs_dir_operations = {
42 .open = autofs_dir_open,
43 .release = dcache_dir_close,
44 .read = generic_read_dir,
45 .iterate_shared = dcache_readdir,
46 .llseek = dcache_dir_lseek,
47 };
48
49 const struct inode_operations autofs_dir_inode_operations = {
50 .lookup = autofs_lookup,
51 .unlink = autofs_dir_unlink,
52 .symlink = autofs_dir_symlink,
53 .mkdir = autofs_dir_mkdir,
54 .rmdir = autofs_dir_rmdir,
55 };
56
57 const struct dentry_operations autofs_dentry_operations = {
58 .d_automount = autofs_d_automount,
59 .d_manage = autofs_d_manage,
60 .d_release = autofs_dentry_release,
61 };
62
autofs_del_active(struct dentry * dentry)63 static void autofs_del_active(struct dentry *dentry)
64 {
65 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
66 struct autofs_info *ino;
67
68 ino = autofs_dentry_ino(dentry);
69 spin_lock(&sbi->lookup_lock);
70 list_del_init(&ino->active);
71 spin_unlock(&sbi->lookup_lock);
72 }
73
autofs_dir_open(struct inode * inode,struct file * file)74 static int autofs_dir_open(struct inode *inode, struct file *file)
75 {
76 struct dentry *dentry = file->f_path.dentry;
77 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
78
79 pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
80
81 if (autofs_oz_mode(sbi))
82 goto out;
83
84 /*
85 * An empty directory in an autofs file system is always a
86 * mount point. The daemon must have failed to mount this
87 * during lookup so it doesn't exist. This can happen, for
88 * example, if user space returns an incorrect status for a
89 * mount request. Otherwise we're doing a readdir on the
90 * autofs file system so just let the libfs routines handle
91 * it.
92 */
93 spin_lock(&sbi->lookup_lock);
94 if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {
95 spin_unlock(&sbi->lookup_lock);
96 return -ENOENT;
97 }
98 spin_unlock(&sbi->lookup_lock);
99
100 out:
101 return dcache_dir_open(inode, file);
102 }
103
autofs_dentry_release(struct dentry * de)104 static void autofs_dentry_release(struct dentry *de)
105 {
106 struct autofs_info *ino = autofs_dentry_ino(de);
107 struct autofs_sb_info *sbi = autofs_sbi(de->d_sb);
108
109 pr_debug("releasing %p\n", de);
110
111 if (!ino)
112 return;
113
114 if (sbi) {
115 spin_lock(&sbi->lookup_lock);
116 if (!list_empty(&ino->active))
117 list_del(&ino->active);
118 if (!list_empty(&ino->expiring))
119 list_del(&ino->expiring);
120 spin_unlock(&sbi->lookup_lock);
121 }
122
123 autofs_free_ino(ino);
124 }
125
autofs_lookup_active(struct dentry * dentry)126 static struct dentry *autofs_lookup_active(struct dentry *dentry)
127 {
128 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
129 struct dentry *parent = dentry->d_parent;
130 const struct qstr *name = &dentry->d_name;
131 unsigned int len = name->len;
132 unsigned int hash = name->hash;
133 const unsigned char *str = name->name;
134 struct list_head *p, *head;
135
136 head = &sbi->active_list;
137 if (list_empty(head))
138 return NULL;
139 spin_lock(&sbi->lookup_lock);
140 list_for_each(p, head) {
141 struct autofs_info *ino;
142 struct dentry *active;
143 const struct qstr *qstr;
144
145 ino = list_entry(p, struct autofs_info, active);
146 active = ino->dentry;
147
148 spin_lock(&active->d_lock);
149
150 /* Already gone? */
151 if ((int) d_count(active) <= 0)
152 goto next;
153
154 qstr = &active->d_name;
155
156 if (active->d_name.hash != hash)
157 goto next;
158 if (active->d_parent != parent)
159 goto next;
160
161 if (qstr->len != len)
162 goto next;
163 if (memcmp(qstr->name, str, len))
164 goto next;
165
166 if (d_unhashed(active)) {
167 dget_dlock(active);
168 spin_unlock(&active->d_lock);
169 spin_unlock(&sbi->lookup_lock);
170 return active;
171 }
172 next:
173 spin_unlock(&active->d_lock);
174 }
175 spin_unlock(&sbi->lookup_lock);
176
177 return NULL;
178 }
179
autofs_lookup_expiring(struct dentry * dentry,bool rcu_walk)180 static struct dentry *autofs_lookup_expiring(struct dentry *dentry,
181 bool rcu_walk)
182 {
183 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
184 struct dentry *parent = dentry->d_parent;
185 const struct qstr *name = &dentry->d_name;
186 unsigned int len = name->len;
187 unsigned int hash = name->hash;
188 const unsigned char *str = name->name;
189 struct list_head *p, *head;
190
191 head = &sbi->expiring_list;
192 if (list_empty(head))
193 return NULL;
194 spin_lock(&sbi->lookup_lock);
195 list_for_each(p, head) {
196 struct autofs_info *ino;
197 struct dentry *expiring;
198 const struct qstr *qstr;
199
200 if (rcu_walk) {
201 spin_unlock(&sbi->lookup_lock);
202 return ERR_PTR(-ECHILD);
203 }
204
205 ino = list_entry(p, struct autofs_info, expiring);
206 expiring = ino->dentry;
207
208 spin_lock(&expiring->d_lock);
209
210 /* We've already been dentry_iput or unlinked */
211 if (d_really_is_negative(expiring))
212 goto next;
213
214 qstr = &expiring->d_name;
215
216 if (expiring->d_name.hash != hash)
217 goto next;
218 if (expiring->d_parent != parent)
219 goto next;
220
221 if (qstr->len != len)
222 goto next;
223 if (memcmp(qstr->name, str, len))
224 goto next;
225
226 if (d_unhashed(expiring)) {
227 dget_dlock(expiring);
228 spin_unlock(&expiring->d_lock);
229 spin_unlock(&sbi->lookup_lock);
230 return expiring;
231 }
232 next:
233 spin_unlock(&expiring->d_lock);
234 }
235 spin_unlock(&sbi->lookup_lock);
236
237 return NULL;
238 }
239
autofs_mount_wait(const struct path * path,bool rcu_walk)240 static int autofs_mount_wait(const struct path *path, bool rcu_walk)
241 {
242 struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
243 struct autofs_info *ino = autofs_dentry_ino(path->dentry);
244 int status = 0;
245
246 if (ino->flags & AUTOFS_INF_PENDING) {
247 if (rcu_walk)
248 return -ECHILD;
249 pr_debug("waiting for mount name=%pd\n", path->dentry);
250 status = autofs_wait(sbi, path, NFY_MOUNT);
251 pr_debug("mount wait done status=%d\n", status);
252 ino->last_used = jiffies;
253 return status;
254 }
255 if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
256 ino->last_used = jiffies;
257 return status;
258 }
259
do_expire_wait(const struct path * path,bool rcu_walk)260 static int do_expire_wait(const struct path *path, bool rcu_walk)
261 {
262 struct dentry *dentry = path->dentry;
263 struct dentry *expiring;
264
265 expiring = autofs_lookup_expiring(dentry, rcu_walk);
266 if (IS_ERR(expiring))
267 return PTR_ERR(expiring);
268 if (!expiring)
269 return autofs_expire_wait(path, rcu_walk);
270 else {
271 const struct path this = { .mnt = path->mnt, .dentry = expiring };
272 /*
273 * If we are racing with expire the request might not
274 * be quite complete, but the directory has been removed
275 * so it must have been successful, just wait for it.
276 */
277 autofs_expire_wait(&this, 0);
278 autofs_del_expiring(expiring);
279 dput(expiring);
280 }
281 return 0;
282 }
283
autofs_mountpoint_changed(struct path * path)284 static struct dentry *autofs_mountpoint_changed(struct path *path)
285 {
286 struct dentry *dentry = path->dentry;
287 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
288
289 /*
290 * If this is an indirect mount the dentry could have gone away
291 * as a result of an expire and a new one created.
292 */
293 if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
294 struct dentry *parent = dentry->d_parent;
295 struct autofs_info *ino;
296 struct dentry *new;
297
298 new = d_lookup(parent, &dentry->d_name);
299 if (!new)
300 return NULL;
301 ino = autofs_dentry_ino(new);
302 ino->last_used = jiffies;
303 dput(path->dentry);
304 path->dentry = new;
305 }
306 return path->dentry;
307 }
308
autofs_d_automount(struct path * path)309 static struct vfsmount *autofs_d_automount(struct path *path)
310 {
311 struct dentry *dentry = path->dentry;
312 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
313 struct autofs_info *ino = autofs_dentry_ino(dentry);
314 int status;
315
316 pr_debug("dentry=%p %pd\n", dentry, dentry);
317
318 /* The daemon never triggers a mount. */
319 if (autofs_oz_mode(sbi))
320 return NULL;
321
322 /*
323 * If an expire request is pending everyone must wait.
324 * If the expire fails we're still mounted so continue
325 * the follow and return. A return of -EAGAIN (which only
326 * happens with indirect mounts) means the expire completed
327 * and the directory was removed, so just go ahead and try
328 * the mount.
329 */
330 status = do_expire_wait(path, 0);
331 if (status && status != -EAGAIN)
332 return NULL;
333
334 /* Callback to the daemon to perform the mount or wait */
335 spin_lock(&sbi->fs_lock);
336 if (ino->flags & AUTOFS_INF_PENDING) {
337 spin_unlock(&sbi->fs_lock);
338 status = autofs_mount_wait(path, 0);
339 if (status)
340 return ERR_PTR(status);
341 goto done;
342 }
343
344 /*
345 * If the dentry is a symlink it's equivalent to a directory
346 * having path_is_mountpoint() true, so there's no need to call
347 * back to the daemon.
348 */
349 if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
350 spin_unlock(&sbi->fs_lock);
351 goto done;
352 }
353
354 if (!path_is_mountpoint(path)) {
355 /*
356 * It's possible that user space hasn't removed directories
357 * after umounting a rootless multi-mount, although it
358 * should. For v5 path_has_submounts() is sufficient to
359 * handle this because the leaves of the directory tree under
360 * the mount never trigger mounts themselves (they have an
361 * autofs trigger mount mounted on them). But v4 pseudo direct
362 * mounts do need the leaves to trigger mounts. In this case
363 * we have no choice but to use the list_empty() check and
364 * require user space behave.
365 */
366 if (sbi->version > 4) {
367 if (path_has_submounts(path)) {
368 spin_unlock(&sbi->fs_lock);
369 goto done;
370 }
371 } else {
372 if (!simple_empty(dentry)) {
373 spin_unlock(&sbi->fs_lock);
374 goto done;
375 }
376 }
377 ino->flags |= AUTOFS_INF_PENDING;
378 spin_unlock(&sbi->fs_lock);
379 status = autofs_mount_wait(path, 0);
380 spin_lock(&sbi->fs_lock);
381 ino->flags &= ~AUTOFS_INF_PENDING;
382 if (status) {
383 spin_unlock(&sbi->fs_lock);
384 return ERR_PTR(status);
385 }
386 }
387 spin_unlock(&sbi->fs_lock);
388 done:
389 /* Mount succeeded, check if we ended up with a new dentry */
390 dentry = autofs_mountpoint_changed(path);
391 if (!dentry)
392 return ERR_PTR(-ENOENT);
393
394 return NULL;
395 }
396
autofs_d_manage(const struct path * path,bool rcu_walk)397 static int autofs_d_manage(const struct path *path, bool rcu_walk)
398 {
399 struct dentry *dentry = path->dentry;
400 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
401 struct autofs_info *ino = autofs_dentry_ino(dentry);
402 int status;
403
404 pr_debug("dentry=%p %pd\n", dentry, dentry);
405
406 /* The daemon never waits. */
407 if (autofs_oz_mode(sbi)) {
408 if (!path_is_mountpoint(path))
409 return -EISDIR;
410 return 0;
411 }
412
413 /* Wait for pending expires */
414 if (do_expire_wait(path, rcu_walk) == -ECHILD)
415 return -ECHILD;
416
417 /*
418 * This dentry may be under construction so wait on mount
419 * completion.
420 */
421 status = autofs_mount_wait(path, rcu_walk);
422 if (status)
423 return status;
424
425 if (rcu_walk) {
426 /* We don't need fs_lock in rcu_walk mode,
427 * just testing 'AUTOFS_INFO_NO_RCU' is enough.
428 * simple_empty() takes a spinlock, so leave it
429 * to last.
430 * We only return -EISDIR when certain this isn't
431 * a mount-trap.
432 */
433 struct inode *inode;
434
435 if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
436 return 0;
437 if (path_is_mountpoint(path))
438 return 0;
439 inode = d_inode_rcu(dentry);
440 if (inode && S_ISLNK(inode->i_mode))
441 return -EISDIR;
442 if (list_empty(&dentry->d_subdirs))
443 return 0;
444 if (!simple_empty(dentry))
445 return -EISDIR;
446 return 0;
447 }
448
449 spin_lock(&sbi->fs_lock);
450 /*
451 * If the dentry has been selected for expire while we slept
452 * on the lock then it might go away. We'll deal with that in
453 * ->d_automount() and wait on a new mount if the expire
454 * succeeds or return here if it doesn't (since there's no
455 * mount to follow with a rootless multi-mount).
456 */
457 if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
458 /*
459 * Any needed mounting has been completed and the path
460 * updated so check if this is a rootless multi-mount so
461 * we can avoid needless calls ->d_automount() and avoid
462 * an incorrect ELOOP error return.
463 */
464 if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
465 (d_really_is_positive(dentry) && d_is_symlink(dentry)))
466 status = -EISDIR;
467 }
468 spin_unlock(&sbi->fs_lock);
469
470 return status;
471 }
472
473 /* Lookups in the root directory */
autofs_lookup(struct inode * dir,struct dentry * dentry,unsigned int flags)474 static struct dentry *autofs_lookup(struct inode *dir,
475 struct dentry *dentry, unsigned int flags)
476 {
477 struct autofs_sb_info *sbi;
478 struct autofs_info *ino;
479 struct dentry *active;
480
481 pr_debug("name = %pd\n", dentry);
482
483 /* File name too long to exist */
484 if (dentry->d_name.len > NAME_MAX)
485 return ERR_PTR(-ENAMETOOLONG);
486
487 sbi = autofs_sbi(dir->i_sb);
488
489 pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
490 current->pid, task_pgrp_nr(current),
491 sbi->flags & AUTOFS_SBI_CATATONIC,
492 autofs_oz_mode(sbi));
493
494 active = autofs_lookup_active(dentry);
495 if (active)
496 return active;
497 else {
498 /*
499 * A dentry that is not within the root can never trigger a
500 * mount operation, unless the directory already exists, so we
501 * can return fail immediately. The daemon however does need
502 * to create directories within the file system.
503 */
504 if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
505 return ERR_PTR(-ENOENT);
506
507 ino = autofs_new_ino(sbi);
508 if (!ino)
509 return ERR_PTR(-ENOMEM);
510
511 spin_lock(&sbi->lookup_lock);
512 spin_lock(&dentry->d_lock);
513 /* Mark entries in the root as mount triggers */
514 if (IS_ROOT(dentry->d_parent) &&
515 autofs_type_indirect(sbi->type))
516 __managed_dentry_set_managed(dentry);
517 dentry->d_fsdata = ino;
518 ino->dentry = dentry;
519
520 list_add(&ino->active, &sbi->active_list);
521 spin_unlock(&sbi->lookup_lock);
522 spin_unlock(&dentry->d_lock);
523 }
524 return NULL;
525 }
526
autofs_dir_symlink(struct inode * dir,struct dentry * dentry,const char * symname)527 static int autofs_dir_symlink(struct inode *dir,
528 struct dentry *dentry,
529 const char *symname)
530 {
531 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
532 struct autofs_info *ino = autofs_dentry_ino(dentry);
533 struct autofs_info *p_ino;
534 struct inode *inode;
535 size_t size = strlen(symname);
536 char *cp;
537
538 pr_debug("%s <- %pd\n", symname, dentry);
539
540 if (!autofs_oz_mode(sbi))
541 return -EACCES;
542
543 /* autofs_oz_mode() needs to allow path walks when the
544 * autofs mount is catatonic but the state of an autofs
545 * file system needs to be preserved over restarts.
546 */
547 if (sbi->flags & AUTOFS_SBI_CATATONIC)
548 return -EACCES;
549
550 BUG_ON(!ino);
551
552 autofs_clean_ino(ino);
553
554 autofs_del_active(dentry);
555
556 cp = kmalloc(size + 1, GFP_KERNEL);
557 if (!cp)
558 return -ENOMEM;
559
560 strcpy(cp, symname);
561
562 inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555);
563 if (!inode) {
564 kfree(cp);
565 return -ENOMEM;
566 }
567 inode->i_private = cp;
568 inode->i_size = size;
569 d_add(dentry, inode);
570
571 dget(dentry);
572 ino->count++;
573 p_ino = autofs_dentry_ino(dentry->d_parent);
574 p_ino->count++;
575
576 dir->i_mtime = current_time(dir);
577
578 return 0;
579 }
580
581 /*
582 * NOTE!
583 *
584 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
585 * that the file no longer exists. However, doing that means that the
586 * VFS layer can turn the dentry into a negative dentry. We don't want
587 * this, because the unlink is probably the result of an expire.
588 * We simply d_drop it and add it to a expiring list in the super block,
589 * which allows the dentry lookup to check for an incomplete expire.
590 *
591 * If a process is blocked on the dentry waiting for the expire to finish,
592 * it will invalidate the dentry and try to mount with a new one.
593 *
594 * Also see autofs_dir_rmdir()..
595 */
autofs_dir_unlink(struct inode * dir,struct dentry * dentry)596 static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
597 {
598 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
599 struct autofs_info *ino = autofs_dentry_ino(dentry);
600 struct autofs_info *p_ino;
601
602 if (!autofs_oz_mode(sbi))
603 return -EACCES;
604
605 /* autofs_oz_mode() needs to allow path walks when the
606 * autofs mount is catatonic but the state of an autofs
607 * file system needs to be preserved over restarts.
608 */
609 if (sbi->flags & AUTOFS_SBI_CATATONIC)
610 return -EACCES;
611
612 ino->count--;
613 p_ino = autofs_dentry_ino(dentry->d_parent);
614 p_ino->count--;
615 dput(ino->dentry);
616
617 d_inode(dentry)->i_size = 0;
618 clear_nlink(d_inode(dentry));
619
620 dir->i_mtime = current_time(dir);
621
622 spin_lock(&sbi->lookup_lock);
623 __autofs_add_expiring(dentry);
624 d_drop(dentry);
625 spin_unlock(&sbi->lookup_lock);
626
627 return 0;
628 }
629
630 /*
631 * Version 4 of autofs provides a pseudo direct mount implementation
632 * that relies on directories at the leaves of a directory tree under
633 * an indirect mount to trigger mounts. To allow for this we need to
634 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
635 * of the directory tree. There is no need to clear the automount flag
636 * following a mount or restore it after an expire because these mounts
637 * are always covered. However, it is necessary to ensure that these
638 * flags are clear on non-empty directories to avoid unnecessary calls
639 * during path walks.
640 */
autofs_set_leaf_automount_flags(struct dentry * dentry)641 static void autofs_set_leaf_automount_flags(struct dentry *dentry)
642 {
643 struct dentry *parent;
644
645 /* root and dentrys in the root are already handled */
646 if (IS_ROOT(dentry->d_parent))
647 return;
648
649 managed_dentry_set_managed(dentry);
650
651 parent = dentry->d_parent;
652 /* only consider parents below dentrys in the root */
653 if (IS_ROOT(parent->d_parent))
654 return;
655 managed_dentry_clear_managed(parent);
656 }
657
autofs_clear_leaf_automount_flags(struct dentry * dentry)658 static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
659 {
660 struct dentry *parent;
661
662 /* flags for dentrys in the root are handled elsewhere */
663 if (IS_ROOT(dentry->d_parent))
664 return;
665
666 managed_dentry_clear_managed(dentry);
667
668 parent = dentry->d_parent;
669 /* only consider parents below dentrys in the root */
670 if (IS_ROOT(parent->d_parent))
671 return;
672 if (autofs_dentry_ino(parent)->count == 2)
673 managed_dentry_set_managed(parent);
674 }
675
autofs_dir_rmdir(struct inode * dir,struct dentry * dentry)676 static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
677 {
678 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
679 struct autofs_info *ino = autofs_dentry_ino(dentry);
680 struct autofs_info *p_ino;
681
682 pr_debug("dentry %p, removing %pd\n", dentry, dentry);
683
684 if (!autofs_oz_mode(sbi))
685 return -EACCES;
686
687 /* autofs_oz_mode() needs to allow path walks when the
688 * autofs mount is catatonic but the state of an autofs
689 * file system needs to be preserved over restarts.
690 */
691 if (sbi->flags & AUTOFS_SBI_CATATONIC)
692 return -EACCES;
693
694 if (ino->count != 1)
695 return -ENOTEMPTY;
696
697 spin_lock(&sbi->lookup_lock);
698 __autofs_add_expiring(dentry);
699 d_drop(dentry);
700 spin_unlock(&sbi->lookup_lock);
701
702 if (sbi->version < 5)
703 autofs_clear_leaf_automount_flags(dentry);
704
705 ino->count--;
706 p_ino = autofs_dentry_ino(dentry->d_parent);
707 p_ino->count--;
708 dput(ino->dentry);
709 d_inode(dentry)->i_size = 0;
710 clear_nlink(d_inode(dentry));
711
712 if (dir->i_nlink)
713 drop_nlink(dir);
714
715 return 0;
716 }
717
autofs_dir_mkdir(struct inode * dir,struct dentry * dentry,umode_t mode)718 static int autofs_dir_mkdir(struct inode *dir,
719 struct dentry *dentry, umode_t mode)
720 {
721 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
722 struct autofs_info *ino = autofs_dentry_ino(dentry);
723 struct autofs_info *p_ino;
724 struct inode *inode;
725
726 if (!autofs_oz_mode(sbi))
727 return -EACCES;
728
729 /* autofs_oz_mode() needs to allow path walks when the
730 * autofs mount is catatonic but the state of an autofs
731 * file system needs to be preserved over restarts.
732 */
733 if (sbi->flags & AUTOFS_SBI_CATATONIC)
734 return -EACCES;
735
736 pr_debug("dentry %p, creating %pd\n", dentry, dentry);
737
738 BUG_ON(!ino);
739
740 autofs_clean_ino(ino);
741
742 autofs_del_active(dentry);
743
744 inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode);
745 if (!inode)
746 return -ENOMEM;
747 d_add(dentry, inode);
748
749 if (sbi->version < 5)
750 autofs_set_leaf_automount_flags(dentry);
751
752 dget(dentry);
753 ino->count++;
754 p_ino = autofs_dentry_ino(dentry->d_parent);
755 p_ino->count++;
756 inc_nlink(dir);
757 dir->i_mtime = current_time(dir);
758
759 return 0;
760 }
761
762 /* Get/set timeout ioctl() operation */
763 #ifdef CONFIG_COMPAT
autofs_compat_get_set_timeout(struct autofs_sb_info * sbi,compat_ulong_t __user * p)764 static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
765 compat_ulong_t __user *p)
766 {
767 unsigned long ntimeout;
768 int rv;
769
770 rv = get_user(ntimeout, p);
771 if (rv)
772 goto error;
773
774 rv = put_user(sbi->exp_timeout/HZ, p);
775 if (rv)
776 goto error;
777
778 if (ntimeout > UINT_MAX/HZ)
779 sbi->exp_timeout = 0;
780 else
781 sbi->exp_timeout = ntimeout * HZ;
782
783 return 0;
784 error:
785 return rv;
786 }
787 #endif
788
autofs_get_set_timeout(struct autofs_sb_info * sbi,unsigned long __user * p)789 static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
790 unsigned long __user *p)
791 {
792 unsigned long ntimeout;
793 int rv;
794
795 rv = get_user(ntimeout, p);
796 if (rv)
797 goto error;
798
799 rv = put_user(sbi->exp_timeout/HZ, p);
800 if (rv)
801 goto error;
802
803 if (ntimeout > ULONG_MAX/HZ)
804 sbi->exp_timeout = 0;
805 else
806 sbi->exp_timeout = ntimeout * HZ;
807
808 return 0;
809 error:
810 return rv;
811 }
812
813 /* Return protocol version */
autofs_get_protover(struct autofs_sb_info * sbi,int __user * p)814 static inline int autofs_get_protover(struct autofs_sb_info *sbi,
815 int __user *p)
816 {
817 return put_user(sbi->version, p);
818 }
819
820 /* Return protocol sub version */
autofs_get_protosubver(struct autofs_sb_info * sbi,int __user * p)821 static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
822 int __user *p)
823 {
824 return put_user(sbi->sub_version, p);
825 }
826
827 /*
828 * Tells the daemon whether it can umount the autofs mount.
829 */
autofs_ask_umount(struct vfsmount * mnt,int __user * p)830 static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
831 {
832 int status = 0;
833
834 if (may_umount(mnt))
835 status = 1;
836
837 pr_debug("may umount %d\n", status);
838
839 status = put_user(status, p);
840
841 return status;
842 }
843
844 /* Identify autofs_dentries - this is so we can tell if there's
845 * an extra dentry refcount or not. We only hold a refcount on the
846 * dentry if its non-negative (ie, d_inode != NULL)
847 */
is_autofs_dentry(struct dentry * dentry)848 int is_autofs_dentry(struct dentry *dentry)
849 {
850 return dentry && d_really_is_positive(dentry) &&
851 dentry->d_op == &autofs_dentry_operations &&
852 dentry->d_fsdata != NULL;
853 }
854
855 /*
856 * ioctl()'s on the root directory is the chief method for the daemon to
857 * generate kernel reactions
858 */
autofs_root_ioctl_unlocked(struct inode * inode,struct file * filp,unsigned int cmd,unsigned long arg)859 static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
860 unsigned int cmd, unsigned long arg)
861 {
862 struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
863 void __user *p = (void __user *)arg;
864
865 pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
866 cmd, arg, sbi, task_pgrp_nr(current));
867
868 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
869 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
870 return -ENOTTY;
871
872 if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
873 return -EPERM;
874
875 switch (cmd) {
876 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
877 return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
878 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
879 return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
880 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
881 autofs_catatonic_mode(sbi);
882 return 0;
883 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
884 return autofs_get_protover(sbi, p);
885 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
886 return autofs_get_protosubver(sbi, p);
887 case AUTOFS_IOC_SETTIMEOUT:
888 return autofs_get_set_timeout(sbi, p);
889 #ifdef CONFIG_COMPAT
890 case AUTOFS_IOC_SETTIMEOUT32:
891 return autofs_compat_get_set_timeout(sbi, p);
892 #endif
893
894 case AUTOFS_IOC_ASKUMOUNT:
895 return autofs_ask_umount(filp->f_path.mnt, p);
896
897 /* return a single thing to expire */
898 case AUTOFS_IOC_EXPIRE:
899 return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
900 /* same as above, but can send multiple expires through pipe */
901 case AUTOFS_IOC_EXPIRE_MULTI:
902 return autofs_expire_multi(inode->i_sb,
903 filp->f_path.mnt, sbi, p);
904
905 default:
906 return -EINVAL;
907 }
908 }
909
autofs_root_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)910 static long autofs_root_ioctl(struct file *filp,
911 unsigned int cmd, unsigned long arg)
912 {
913 struct inode *inode = file_inode(filp);
914
915 return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
916 }
917
918 #ifdef CONFIG_COMPAT
autofs_root_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)919 static long autofs_root_compat_ioctl(struct file *filp,
920 unsigned int cmd, unsigned long arg)
921 {
922 struct inode *inode = file_inode(filp);
923 int ret;
924
925 if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
926 ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
927 else
928 ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
929 (unsigned long) compat_ptr(arg));
930
931 return ret;
932 }
933 #endif
934