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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
13static int autofs_dir_symlink(struct inode *, struct dentry *, const char *);
14static int autofs_dir_unlink(struct inode *, struct dentry *);
15static int autofs_dir_rmdir(struct inode *, struct dentry *);
16static int autofs_dir_mkdir(struct inode *, struct dentry *, umode_t);
17static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
18#ifdef CONFIG_COMPAT
19static long autofs_root_compat_ioctl(struct file *,
20 unsigned int, unsigned long);
21#endif
22static int autofs_dir_open(struct inode *inode, struct file *file);
23static struct dentry *autofs_lookup(struct inode *,
24 struct dentry *, unsigned int);
25static struct vfsmount *autofs_d_automount(struct path *);
26static int autofs_d_manage(const struct path *, bool);
27static void autofs_dentry_release(struct dentry *);
28
29const 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
41const 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
49const 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
57const 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
63static 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
74static 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
100out:
101 return dcache_dir_open(inode, file);
102}
103
104static 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
126static 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 }
172next:
173 spin_unlock(&active->d_lock);
174 }
175 spin_unlock(&sbi->lookup_lock);
176
177 return NULL;
178}
179
180static 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 }
232next:
233 spin_unlock(&expiring->d_lock);
234 }
235 spin_unlock(&sbi->lookup_lock);
236
237 return NULL;
238}
239
240static 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
260static 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
284static 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
309static 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);
388done:
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
397static 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 */
474static 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
527static 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 atomic_inc(&ino->count);
573 p_ino = autofs_dentry_ino(dentry->d_parent);
574 if (p_ino && !IS_ROOT(dentry))
575 atomic_inc(&p_ino->count);
576
577 dir->i_mtime = current_time(dir);
578
579 return 0;
580}
581
582/*
583 * NOTE!
584 *
585 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
586 * that the file no longer exists. However, doing that means that the
587 * VFS layer can turn the dentry into a negative dentry. We don't want
588 * this, because the unlink is probably the result of an expire.
589 * We simply d_drop it and add it to a expiring list in the super block,
590 * which allows the dentry lookup to check for an incomplete expire.
591 *
592 * If a process is blocked on the dentry waiting for the expire to finish,
593 * it will invalidate the dentry and try to mount with a new one.
594 *
595 * Also see autofs_dir_rmdir()..
596 */
597static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
598{
599 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
600 struct autofs_info *ino = autofs_dentry_ino(dentry);
601 struct autofs_info *p_ino;
602
603 if (!autofs_oz_mode(sbi))
604 return -EACCES;
605
606 /* autofs_oz_mode() needs to allow path walks when the
607 * autofs mount is catatonic but the state of an autofs
608 * file system needs to be preserved over restarts.
609 */
610 if (sbi->flags & AUTOFS_SBI_CATATONIC)
611 return -EACCES;
612
613 if (atomic_dec_and_test(&ino->count)) {
614 p_ino = autofs_dentry_ino(dentry->d_parent);
615 if (p_ino && !IS_ROOT(dentry))
616 atomic_dec(&p_ino->count);
617 }
618 dput(ino->dentry);
619
620 d_inode(dentry)->i_size = 0;
621 clear_nlink(d_inode(dentry));
622
623 dir->i_mtime = current_time(dir);
624
625 spin_lock(&sbi->lookup_lock);
626 __autofs_add_expiring(dentry);
627 d_drop(dentry);
628 spin_unlock(&sbi->lookup_lock);
629
630 return 0;
631}
632
633/*
634 * Version 4 of autofs provides a pseudo direct mount implementation
635 * that relies on directories at the leaves of a directory tree under
636 * an indirect mount to trigger mounts. To allow for this we need to
637 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
638 * of the directory tree. There is no need to clear the automount flag
639 * following a mount or restore it after an expire because these mounts
640 * are always covered. However, it is necessary to ensure that these
641 * flags are clear on non-empty directories to avoid unnecessary calls
642 * during path walks.
643 */
644static void autofs_set_leaf_automount_flags(struct dentry *dentry)
645{
646 struct dentry *parent;
647
648 /* root and dentrys in the root are already handled */
649 if (IS_ROOT(dentry->d_parent))
650 return;
651
652 managed_dentry_set_managed(dentry);
653
654 parent = dentry->d_parent;
655 /* only consider parents below dentrys in the root */
656 if (IS_ROOT(parent->d_parent))
657 return;
658 managed_dentry_clear_managed(parent);
659}
660
661static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
662{
663 struct list_head *d_child;
664 struct dentry *parent;
665
666 /* flags for dentrys in the root are handled elsewhere */
667 if (IS_ROOT(dentry->d_parent))
668 return;
669
670 managed_dentry_clear_managed(dentry);
671
672 parent = dentry->d_parent;
673 /* only consider parents below dentrys in the root */
674 if (IS_ROOT(parent->d_parent))
675 return;
676 d_child = &dentry->d_child;
677 /* Set parent managed if it's becoming empty */
678 if (d_child->next == &parent->d_subdirs &&
679 d_child->prev == &parent->d_subdirs)
680 managed_dentry_set_managed(parent);
681}
682
683static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
684{
685 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
686 struct autofs_info *ino = autofs_dentry_ino(dentry);
687 struct autofs_info *p_ino;
688
689 pr_debug("dentry %p, removing %pd\n", dentry, dentry);
690
691 if (!autofs_oz_mode(sbi))
692 return -EACCES;
693
694 /* autofs_oz_mode() needs to allow path walks when the
695 * autofs mount is catatonic but the state of an autofs
696 * file system needs to be preserved over restarts.
697 */
698 if (sbi->flags & AUTOFS_SBI_CATATONIC)
699 return -EACCES;
700
701 spin_lock(&sbi->lookup_lock);
702 if (!simple_empty(dentry)) {
703 spin_unlock(&sbi->lookup_lock);
704 return -ENOTEMPTY;
705 }
706 __autofs_add_expiring(dentry);
707 d_drop(dentry);
708 spin_unlock(&sbi->lookup_lock);
709
710 if (sbi->version < 5)
711 autofs_clear_leaf_automount_flags(dentry);
712
713 if (atomic_dec_and_test(&ino->count)) {
714 p_ino = autofs_dentry_ino(dentry->d_parent);
715 if (p_ino && dentry->d_parent != dentry)
716 atomic_dec(&p_ino->count);
717 }
718 dput(ino->dentry);
719 d_inode(dentry)->i_size = 0;
720 clear_nlink(d_inode(dentry));
721
722 if (dir->i_nlink)
723 drop_nlink(dir);
724
725 return 0;
726}
727
728static int autofs_dir_mkdir(struct inode *dir,
729 struct dentry *dentry, umode_t mode)
730{
731 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
732 struct autofs_info *ino = autofs_dentry_ino(dentry);
733 struct autofs_info *p_ino;
734 struct inode *inode;
735
736 if (!autofs_oz_mode(sbi))
737 return -EACCES;
738
739 /* autofs_oz_mode() needs to allow path walks when the
740 * autofs mount is catatonic but the state of an autofs
741 * file system needs to be preserved over restarts.
742 */
743 if (sbi->flags & AUTOFS_SBI_CATATONIC)
744 return -EACCES;
745
746 pr_debug("dentry %p, creating %pd\n", dentry, dentry);
747
748 BUG_ON(!ino);
749
750 autofs_clean_ino(ino);
751
752 autofs_del_active(dentry);
753
754 inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode);
755 if (!inode)
756 return -ENOMEM;
757 d_add(dentry, inode);
758
759 if (sbi->version < 5)
760 autofs_set_leaf_automount_flags(dentry);
761
762 dget(dentry);
763 atomic_inc(&ino->count);
764 p_ino = autofs_dentry_ino(dentry->d_parent);
765 if (p_ino && !IS_ROOT(dentry))
766 atomic_inc(&p_ino->count);
767 inc_nlink(dir);
768 dir->i_mtime = current_time(dir);
769
770 return 0;
771}
772
773/* Get/set timeout ioctl() operation */
774#ifdef CONFIG_COMPAT
775static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
776 compat_ulong_t __user *p)
777{
778 unsigned long ntimeout;
779 int rv;
780
781 rv = get_user(ntimeout, p);
782 if (rv)
783 goto error;
784
785 rv = put_user(sbi->exp_timeout/HZ, p);
786 if (rv)
787 goto error;
788
789 if (ntimeout > UINT_MAX/HZ)
790 sbi->exp_timeout = 0;
791 else
792 sbi->exp_timeout = ntimeout * HZ;
793
794 return 0;
795error:
796 return rv;
797}
798#endif
799
800static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
801 unsigned long __user *p)
802{
803 unsigned long ntimeout;
804 int rv;
805
806 rv = get_user(ntimeout, p);
807 if (rv)
808 goto error;
809
810 rv = put_user(sbi->exp_timeout/HZ, p);
811 if (rv)
812 goto error;
813
814 if (ntimeout > ULONG_MAX/HZ)
815 sbi->exp_timeout = 0;
816 else
817 sbi->exp_timeout = ntimeout * HZ;
818
819 return 0;
820error:
821 return rv;
822}
823
824/* Return protocol version */
825static inline int autofs_get_protover(struct autofs_sb_info *sbi,
826 int __user *p)
827{
828 return put_user(sbi->version, p);
829}
830
831/* Return protocol sub version */
832static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
833 int __user *p)
834{
835 return put_user(sbi->sub_version, p);
836}
837
838/*
839* Tells the daemon whether it can umount the autofs mount.
840*/
841static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
842{
843 int status = 0;
844
845 if (may_umount(mnt))
846 status = 1;
847
848 pr_debug("may umount %d\n", status);
849
850 status = put_user(status, p);
851
852 return status;
853}
854
855/* Identify autofs_dentries - this is so we can tell if there's
856 * an extra dentry refcount or not. We only hold a refcount on the
857 * dentry if its non-negative (ie, d_inode != NULL)
858 */
859int is_autofs_dentry(struct dentry *dentry)
860{
861 return dentry && d_really_is_positive(dentry) &&
862 dentry->d_op == &autofs_dentry_operations &&
863 dentry->d_fsdata != NULL;
864}
865
866/*
867 * ioctl()'s on the root directory is the chief method for the daemon to
868 * generate kernel reactions
869 */
870static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
871 unsigned int cmd, unsigned long arg)
872{
873 struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
874 void __user *p = (void __user *)arg;
875
876 pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
877 cmd, arg, sbi, task_pgrp_nr(current));
878
879 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
880 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
881 return -ENOTTY;
882
883 if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
884 return -EPERM;
885
886 switch (cmd) {
887 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
888 return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
889 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
890 return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
891 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
892 autofs_catatonic_mode(sbi);
893 return 0;
894 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
895 return autofs_get_protover(sbi, p);
896 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
897 return autofs_get_protosubver(sbi, p);
898 case AUTOFS_IOC_SETTIMEOUT:
899 return autofs_get_set_timeout(sbi, p);
900#ifdef CONFIG_COMPAT
901 case AUTOFS_IOC_SETTIMEOUT32:
902 return autofs_compat_get_set_timeout(sbi, p);
903#endif
904
905 case AUTOFS_IOC_ASKUMOUNT:
906 return autofs_ask_umount(filp->f_path.mnt, p);
907
908 /* return a single thing to expire */
909 case AUTOFS_IOC_EXPIRE:
910 return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
911 /* same as above, but can send multiple expires through pipe */
912 case AUTOFS_IOC_EXPIRE_MULTI:
913 return autofs_expire_multi(inode->i_sb,
914 filp->f_path.mnt, sbi, p);
915
916 default:
917 return -EINVAL;
918 }
919}
920
921static long autofs_root_ioctl(struct file *filp,
922 unsigned int cmd, unsigned long arg)
923{
924 struct inode *inode = file_inode(filp);
925
926 return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
927}
928
929#ifdef CONFIG_COMPAT
930static long autofs_root_compat_ioctl(struct file *filp,
931 unsigned int cmd, unsigned long arg)
932{
933 struct inode *inode = file_inode(filp);
934 int ret;
935
936 if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
937 ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
938 else
939 ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
940 (unsigned long) compat_ptr(arg));
941
942 return ret;
943}
944#endif
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
13static int autofs_dir_symlink(struct user_namespace *, struct inode *,
14 struct dentry *, const char *);
15static int autofs_dir_unlink(struct inode *, struct dentry *);
16static int autofs_dir_rmdir(struct inode *, struct dentry *);
17static int autofs_dir_mkdir(struct user_namespace *, struct inode *,
18 struct dentry *, umode_t);
19static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
20#ifdef CONFIG_COMPAT
21static long autofs_root_compat_ioctl(struct file *,
22 unsigned int, unsigned long);
23#endif
24static int autofs_dir_open(struct inode *inode, struct file *file);
25static struct dentry *autofs_lookup(struct inode *,
26 struct dentry *, unsigned int);
27static struct vfsmount *autofs_d_automount(struct path *);
28static int autofs_d_manage(const struct path *, bool);
29static void autofs_dentry_release(struct dentry *);
30
31const struct file_operations autofs_root_operations = {
32 .open = dcache_dir_open,
33 .release = dcache_dir_close,
34 .read = generic_read_dir,
35 .iterate_shared = dcache_readdir,
36 .llseek = dcache_dir_lseek,
37 .unlocked_ioctl = autofs_root_ioctl,
38#ifdef CONFIG_COMPAT
39 .compat_ioctl = autofs_root_compat_ioctl,
40#endif
41};
42
43const struct file_operations autofs_dir_operations = {
44 .open = autofs_dir_open,
45 .release = dcache_dir_close,
46 .read = generic_read_dir,
47 .iterate_shared = dcache_readdir,
48 .llseek = dcache_dir_lseek,
49};
50
51const struct inode_operations autofs_dir_inode_operations = {
52 .lookup = autofs_lookup,
53 .unlink = autofs_dir_unlink,
54 .symlink = autofs_dir_symlink,
55 .mkdir = autofs_dir_mkdir,
56 .rmdir = autofs_dir_rmdir,
57};
58
59const struct dentry_operations autofs_dentry_operations = {
60 .d_automount = autofs_d_automount,
61 .d_manage = autofs_d_manage,
62 .d_release = autofs_dentry_release,
63};
64
65static void autofs_del_active(struct dentry *dentry)
66{
67 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
68 struct autofs_info *ino;
69
70 ino = autofs_dentry_ino(dentry);
71 spin_lock(&sbi->lookup_lock);
72 list_del_init(&ino->active);
73 spin_unlock(&sbi->lookup_lock);
74}
75
76static int autofs_dir_open(struct inode *inode, struct file *file)
77{
78 struct dentry *dentry = file->f_path.dentry;
79 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
80
81 pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
82
83 if (autofs_oz_mode(sbi))
84 goto out;
85
86 /*
87 * An empty directory in an autofs file system is always a
88 * mount point. The daemon must have failed to mount this
89 * during lookup so it doesn't exist. This can happen, for
90 * example, if user space returns an incorrect status for a
91 * mount request. Otherwise we're doing a readdir on the
92 * autofs file system so just let the libfs routines handle
93 * it.
94 */
95 spin_lock(&sbi->lookup_lock);
96 if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {
97 spin_unlock(&sbi->lookup_lock);
98 return -ENOENT;
99 }
100 spin_unlock(&sbi->lookup_lock);
101
102out:
103 return dcache_dir_open(inode, file);
104}
105
106static void autofs_dentry_release(struct dentry *de)
107{
108 struct autofs_info *ino = autofs_dentry_ino(de);
109 struct autofs_sb_info *sbi = autofs_sbi(de->d_sb);
110
111 pr_debug("releasing %p\n", de);
112
113 if (!ino)
114 return;
115
116 if (sbi) {
117 spin_lock(&sbi->lookup_lock);
118 if (!list_empty(&ino->active))
119 list_del(&ino->active);
120 if (!list_empty(&ino->expiring))
121 list_del(&ino->expiring);
122 spin_unlock(&sbi->lookup_lock);
123 }
124
125 autofs_free_ino(ino);
126}
127
128static struct dentry *autofs_lookup_active(struct dentry *dentry)
129{
130 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
131 struct dentry *parent = dentry->d_parent;
132 const struct qstr *name = &dentry->d_name;
133 unsigned int len = name->len;
134 unsigned int hash = name->hash;
135 const unsigned char *str = name->name;
136 struct list_head *p, *head;
137
138 head = &sbi->active_list;
139 if (list_empty(head))
140 return NULL;
141 spin_lock(&sbi->lookup_lock);
142 list_for_each(p, head) {
143 struct autofs_info *ino;
144 struct dentry *active;
145 const struct qstr *qstr;
146
147 ino = list_entry(p, struct autofs_info, active);
148 active = ino->dentry;
149
150 spin_lock(&active->d_lock);
151
152 /* Already gone? */
153 if ((int) d_count(active) <= 0)
154 goto next;
155
156 qstr = &active->d_name;
157
158 if (active->d_name.hash != hash)
159 goto next;
160 if (active->d_parent != parent)
161 goto next;
162
163 if (qstr->len != len)
164 goto next;
165 if (memcmp(qstr->name, str, len))
166 goto next;
167
168 if (d_unhashed(active)) {
169 dget_dlock(active);
170 spin_unlock(&active->d_lock);
171 spin_unlock(&sbi->lookup_lock);
172 return active;
173 }
174next:
175 spin_unlock(&active->d_lock);
176 }
177 spin_unlock(&sbi->lookup_lock);
178
179 return NULL;
180}
181
182static struct dentry *autofs_lookup_expiring(struct dentry *dentry,
183 bool rcu_walk)
184{
185 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
186 struct dentry *parent = dentry->d_parent;
187 const struct qstr *name = &dentry->d_name;
188 unsigned int len = name->len;
189 unsigned int hash = name->hash;
190 const unsigned char *str = name->name;
191 struct list_head *p, *head;
192
193 head = &sbi->expiring_list;
194 if (list_empty(head))
195 return NULL;
196 spin_lock(&sbi->lookup_lock);
197 list_for_each(p, head) {
198 struct autofs_info *ino;
199 struct dentry *expiring;
200 const struct qstr *qstr;
201
202 if (rcu_walk) {
203 spin_unlock(&sbi->lookup_lock);
204 return ERR_PTR(-ECHILD);
205 }
206
207 ino = list_entry(p, struct autofs_info, expiring);
208 expiring = ino->dentry;
209
210 spin_lock(&expiring->d_lock);
211
212 /* We've already been dentry_iput or unlinked */
213 if (d_really_is_negative(expiring))
214 goto next;
215
216 qstr = &expiring->d_name;
217
218 if (expiring->d_name.hash != hash)
219 goto next;
220 if (expiring->d_parent != parent)
221 goto next;
222
223 if (qstr->len != len)
224 goto next;
225 if (memcmp(qstr->name, str, len))
226 goto next;
227
228 if (d_unhashed(expiring)) {
229 dget_dlock(expiring);
230 spin_unlock(&expiring->d_lock);
231 spin_unlock(&sbi->lookup_lock);
232 return expiring;
233 }
234next:
235 spin_unlock(&expiring->d_lock);
236 }
237 spin_unlock(&sbi->lookup_lock);
238
239 return NULL;
240}
241
242static int autofs_mount_wait(const struct path *path, bool rcu_walk)
243{
244 struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
245 struct autofs_info *ino = autofs_dentry_ino(path->dentry);
246 int status = 0;
247
248 if (ino->flags & AUTOFS_INF_PENDING) {
249 if (rcu_walk)
250 return -ECHILD;
251 pr_debug("waiting for mount name=%pd\n", path->dentry);
252 status = autofs_wait(sbi, path, NFY_MOUNT);
253 pr_debug("mount wait done status=%d\n", status);
254 ino->last_used = jiffies;
255 return status;
256 }
257 if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
258 ino->last_used = jiffies;
259 return status;
260}
261
262static int do_expire_wait(const struct path *path, bool rcu_walk)
263{
264 struct dentry *dentry = path->dentry;
265 struct dentry *expiring;
266
267 expiring = autofs_lookup_expiring(dentry, rcu_walk);
268 if (IS_ERR(expiring))
269 return PTR_ERR(expiring);
270 if (!expiring)
271 return autofs_expire_wait(path, rcu_walk);
272 else {
273 const struct path this = { .mnt = path->mnt, .dentry = expiring };
274 /*
275 * If we are racing with expire the request might not
276 * be quite complete, but the directory has been removed
277 * so it must have been successful, just wait for it.
278 */
279 autofs_expire_wait(&this, 0);
280 autofs_del_expiring(expiring);
281 dput(expiring);
282 }
283 return 0;
284}
285
286static struct dentry *autofs_mountpoint_changed(struct path *path)
287{
288 struct dentry *dentry = path->dentry;
289 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
290
291 /*
292 * If this is an indirect mount the dentry could have gone away
293 * as a result of an expire and a new one created.
294 */
295 if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
296 struct dentry *parent = dentry->d_parent;
297 struct autofs_info *ino;
298 struct dentry *new;
299
300 new = d_lookup(parent, &dentry->d_name);
301 if (!new)
302 return NULL;
303 ino = autofs_dentry_ino(new);
304 ino->last_used = jiffies;
305 dput(path->dentry);
306 path->dentry = new;
307 }
308 return path->dentry;
309}
310
311static struct vfsmount *autofs_d_automount(struct path *path)
312{
313 struct dentry *dentry = path->dentry;
314 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
315 struct autofs_info *ino = autofs_dentry_ino(dentry);
316 int status;
317
318 pr_debug("dentry=%p %pd\n", dentry, dentry);
319
320 /* The daemon never triggers a mount. */
321 if (autofs_oz_mode(sbi))
322 return NULL;
323
324 /*
325 * If an expire request is pending everyone must wait.
326 * If the expire fails we're still mounted so continue
327 * the follow and return. A return of -EAGAIN (which only
328 * happens with indirect mounts) means the expire completed
329 * and the directory was removed, so just go ahead and try
330 * the mount.
331 */
332 status = do_expire_wait(path, 0);
333 if (status && status != -EAGAIN)
334 return NULL;
335
336 /* Callback to the daemon to perform the mount or wait */
337 spin_lock(&sbi->fs_lock);
338 if (ino->flags & AUTOFS_INF_PENDING) {
339 spin_unlock(&sbi->fs_lock);
340 status = autofs_mount_wait(path, 0);
341 if (status)
342 return ERR_PTR(status);
343 goto done;
344 }
345
346 /*
347 * If the dentry is a symlink it's equivalent to a directory
348 * having path_is_mountpoint() true, so there's no need to call
349 * back to the daemon.
350 */
351 if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
352 spin_unlock(&sbi->fs_lock);
353 goto done;
354 }
355
356 if (!path_is_mountpoint(path)) {
357 /*
358 * It's possible that user space hasn't removed directories
359 * after umounting a rootless multi-mount, although it
360 * should. For v5 path_has_submounts() is sufficient to
361 * handle this because the leaves of the directory tree under
362 * the mount never trigger mounts themselves (they have an
363 * autofs trigger mount mounted on them). But v4 pseudo direct
364 * mounts do need the leaves to trigger mounts. In this case
365 * we have no choice but to use the list_empty() check and
366 * require user space behave.
367 */
368 if (sbi->version > 4) {
369 if (path_has_submounts(path)) {
370 spin_unlock(&sbi->fs_lock);
371 goto done;
372 }
373 } else {
374 if (!simple_empty(dentry)) {
375 spin_unlock(&sbi->fs_lock);
376 goto done;
377 }
378 }
379 ino->flags |= AUTOFS_INF_PENDING;
380 spin_unlock(&sbi->fs_lock);
381 status = autofs_mount_wait(path, 0);
382 spin_lock(&sbi->fs_lock);
383 ino->flags &= ~AUTOFS_INF_PENDING;
384 if (status) {
385 spin_unlock(&sbi->fs_lock);
386 return ERR_PTR(status);
387 }
388 }
389 spin_unlock(&sbi->fs_lock);
390done:
391 /* Mount succeeded, check if we ended up with a new dentry */
392 dentry = autofs_mountpoint_changed(path);
393 if (!dentry)
394 return ERR_PTR(-ENOENT);
395
396 return NULL;
397}
398
399static int autofs_d_manage(const struct path *path, bool rcu_walk)
400{
401 struct dentry *dentry = path->dentry;
402 struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
403 struct autofs_info *ino = autofs_dentry_ino(dentry);
404 int status;
405
406 pr_debug("dentry=%p %pd\n", dentry, dentry);
407
408 /* The daemon never waits. */
409 if (autofs_oz_mode(sbi)) {
410 if (!path_is_mountpoint(path))
411 return -EISDIR;
412 return 0;
413 }
414
415 /* Wait for pending expires */
416 if (do_expire_wait(path, rcu_walk) == -ECHILD)
417 return -ECHILD;
418
419 /*
420 * This dentry may be under construction so wait on mount
421 * completion.
422 */
423 status = autofs_mount_wait(path, rcu_walk);
424 if (status)
425 return status;
426
427 if (rcu_walk) {
428 /* We don't need fs_lock in rcu_walk mode,
429 * just testing 'AUTOFS_INFO_NO_RCU' is enough.
430 * simple_empty() takes a spinlock, so leave it
431 * to last.
432 * We only return -EISDIR when certain this isn't
433 * a mount-trap.
434 */
435 struct inode *inode;
436
437 if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
438 return 0;
439 if (path_is_mountpoint(path))
440 return 0;
441 inode = d_inode_rcu(dentry);
442 if (inode && S_ISLNK(inode->i_mode))
443 return -EISDIR;
444 if (list_empty(&dentry->d_subdirs))
445 return 0;
446 if (!simple_empty(dentry))
447 return -EISDIR;
448 return 0;
449 }
450
451 spin_lock(&sbi->fs_lock);
452 /*
453 * If the dentry has been selected for expire while we slept
454 * on the lock then it might go away. We'll deal with that in
455 * ->d_automount() and wait on a new mount if the expire
456 * succeeds or return here if it doesn't (since there's no
457 * mount to follow with a rootless multi-mount).
458 */
459 if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
460 /*
461 * Any needed mounting has been completed and the path
462 * updated so check if this is a rootless multi-mount so
463 * we can avoid needless calls ->d_automount() and avoid
464 * an incorrect ELOOP error return.
465 */
466 if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
467 (d_really_is_positive(dentry) && d_is_symlink(dentry)))
468 status = -EISDIR;
469 }
470 spin_unlock(&sbi->fs_lock);
471
472 return status;
473}
474
475/* Lookups in the root directory */
476static struct dentry *autofs_lookup(struct inode *dir,
477 struct dentry *dentry, unsigned int flags)
478{
479 struct autofs_sb_info *sbi;
480 struct autofs_info *ino;
481 struct dentry *active;
482
483 pr_debug("name = %pd\n", dentry);
484
485 /* File name too long to exist */
486 if (dentry->d_name.len > NAME_MAX)
487 return ERR_PTR(-ENAMETOOLONG);
488
489 sbi = autofs_sbi(dir->i_sb);
490
491 pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
492 current->pid, task_pgrp_nr(current),
493 sbi->flags & AUTOFS_SBI_CATATONIC,
494 autofs_oz_mode(sbi));
495
496 active = autofs_lookup_active(dentry);
497 if (active)
498 return active;
499 else {
500 /*
501 * A dentry that is not within the root can never trigger a
502 * mount operation, unless the directory already exists, so we
503 * can return fail immediately. The daemon however does need
504 * to create directories within the file system.
505 */
506 if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
507 return ERR_PTR(-ENOENT);
508
509 ino = autofs_new_ino(sbi);
510 if (!ino)
511 return ERR_PTR(-ENOMEM);
512
513 spin_lock(&sbi->lookup_lock);
514 spin_lock(&dentry->d_lock);
515 /* Mark entries in the root as mount triggers */
516 if (IS_ROOT(dentry->d_parent) &&
517 autofs_type_indirect(sbi->type))
518 __managed_dentry_set_managed(dentry);
519 dentry->d_fsdata = ino;
520 ino->dentry = dentry;
521
522 list_add(&ino->active, &sbi->active_list);
523 spin_unlock(&sbi->lookup_lock);
524 spin_unlock(&dentry->d_lock);
525 }
526 return NULL;
527}
528
529static int autofs_dir_symlink(struct user_namespace *mnt_userns,
530 struct inode *dir, struct dentry *dentry,
531 const char *symname)
532{
533 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
534 struct autofs_info *ino = autofs_dentry_ino(dentry);
535 struct autofs_info *p_ino;
536 struct inode *inode;
537 size_t size = strlen(symname);
538 char *cp;
539
540 pr_debug("%s <- %pd\n", symname, dentry);
541
542 if (!autofs_oz_mode(sbi))
543 return -EACCES;
544
545 /* autofs_oz_mode() needs to allow path walks when the
546 * autofs mount is catatonic but the state of an autofs
547 * file system needs to be preserved over restarts.
548 */
549 if (sbi->flags & AUTOFS_SBI_CATATONIC)
550 return -EACCES;
551
552 BUG_ON(!ino);
553
554 autofs_clean_ino(ino);
555
556 autofs_del_active(dentry);
557
558 cp = kmalloc(size + 1, GFP_KERNEL);
559 if (!cp)
560 return -ENOMEM;
561
562 strcpy(cp, symname);
563
564 inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555);
565 if (!inode) {
566 kfree(cp);
567 return -ENOMEM;
568 }
569 inode->i_private = cp;
570 inode->i_size = size;
571 d_add(dentry, inode);
572
573 dget(dentry);
574 ino->count++;
575 p_ino = autofs_dentry_ino(dentry->d_parent);
576 p_ino->count++;
577
578 dir->i_mtime = current_time(dir);
579
580 return 0;
581}
582
583/*
584 * NOTE!
585 *
586 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
587 * that the file no longer exists. However, doing that means that the
588 * VFS layer can turn the dentry into a negative dentry. We don't want
589 * this, because the unlink is probably the result of an expire.
590 * We simply d_drop it and add it to a expiring list in the super block,
591 * which allows the dentry lookup to check for an incomplete expire.
592 *
593 * If a process is blocked on the dentry waiting for the expire to finish,
594 * it will invalidate the dentry and try to mount with a new one.
595 *
596 * Also see autofs_dir_rmdir()..
597 */
598static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
599{
600 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
601 struct autofs_info *ino = autofs_dentry_ino(dentry);
602 struct autofs_info *p_ino;
603
604 if (!autofs_oz_mode(sbi))
605 return -EACCES;
606
607 /* autofs_oz_mode() needs to allow path walks when the
608 * autofs mount is catatonic but the state of an autofs
609 * file system needs to be preserved over restarts.
610 */
611 if (sbi->flags & AUTOFS_SBI_CATATONIC)
612 return -EACCES;
613
614 ino->count--;
615 p_ino = autofs_dentry_ino(dentry->d_parent);
616 p_ino->count--;
617 dput(ino->dentry);
618
619 d_inode(dentry)->i_size = 0;
620 clear_nlink(d_inode(dentry));
621
622 dir->i_mtime = current_time(dir);
623
624 spin_lock(&sbi->lookup_lock);
625 __autofs_add_expiring(dentry);
626 d_drop(dentry);
627 spin_unlock(&sbi->lookup_lock);
628
629 return 0;
630}
631
632/*
633 * Version 4 of autofs provides a pseudo direct mount implementation
634 * that relies on directories at the leaves of a directory tree under
635 * an indirect mount to trigger mounts. To allow for this we need to
636 * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
637 * of the directory tree. There is no need to clear the automount flag
638 * following a mount or restore it after an expire because these mounts
639 * are always covered. However, it is necessary to ensure that these
640 * flags are clear on non-empty directories to avoid unnecessary calls
641 * during path walks.
642 */
643static void autofs_set_leaf_automount_flags(struct dentry *dentry)
644{
645 struct dentry *parent;
646
647 /* root and dentrys in the root are already handled */
648 if (IS_ROOT(dentry->d_parent))
649 return;
650
651 managed_dentry_set_managed(dentry);
652
653 parent = dentry->d_parent;
654 /* only consider parents below dentrys in the root */
655 if (IS_ROOT(parent->d_parent))
656 return;
657 managed_dentry_clear_managed(parent);
658}
659
660static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
661{
662 struct dentry *parent;
663
664 /* flags for dentrys in the root are handled elsewhere */
665 if (IS_ROOT(dentry->d_parent))
666 return;
667
668 managed_dentry_clear_managed(dentry);
669
670 parent = dentry->d_parent;
671 /* only consider parents below dentrys in the root */
672 if (IS_ROOT(parent->d_parent))
673 return;
674 if (autofs_dentry_ino(parent)->count == 2)
675 managed_dentry_set_managed(parent);
676}
677
678static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
679{
680 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
681 struct autofs_info *ino = autofs_dentry_ino(dentry);
682 struct autofs_info *p_ino;
683
684 pr_debug("dentry %p, removing %pd\n", dentry, dentry);
685
686 if (!autofs_oz_mode(sbi))
687 return -EACCES;
688
689 /* autofs_oz_mode() needs to allow path walks when the
690 * autofs mount is catatonic but the state of an autofs
691 * file system needs to be preserved over restarts.
692 */
693 if (sbi->flags & AUTOFS_SBI_CATATONIC)
694 return -EACCES;
695
696 if (ino->count != 1)
697 return -ENOTEMPTY;
698
699 spin_lock(&sbi->lookup_lock);
700 __autofs_add_expiring(dentry);
701 d_drop(dentry);
702 spin_unlock(&sbi->lookup_lock);
703
704 if (sbi->version < 5)
705 autofs_clear_leaf_automount_flags(dentry);
706
707 ino->count--;
708 p_ino = autofs_dentry_ino(dentry->d_parent);
709 p_ino->count--;
710 dput(ino->dentry);
711 d_inode(dentry)->i_size = 0;
712 clear_nlink(d_inode(dentry));
713
714 if (dir->i_nlink)
715 drop_nlink(dir);
716
717 return 0;
718}
719
720static int autofs_dir_mkdir(struct user_namespace *mnt_userns,
721 struct inode *dir, struct dentry *dentry,
722 umode_t mode)
723{
724 struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
725 struct autofs_info *ino = autofs_dentry_ino(dentry);
726 struct autofs_info *p_ino;
727 struct inode *inode;
728
729 if (!autofs_oz_mode(sbi))
730 return -EACCES;
731
732 /* autofs_oz_mode() needs to allow path walks when the
733 * autofs mount is catatonic but the state of an autofs
734 * file system needs to be preserved over restarts.
735 */
736 if (sbi->flags & AUTOFS_SBI_CATATONIC)
737 return -EACCES;
738
739 pr_debug("dentry %p, creating %pd\n", dentry, dentry);
740
741 BUG_ON(!ino);
742
743 autofs_clean_ino(ino);
744
745 autofs_del_active(dentry);
746
747 inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode);
748 if (!inode)
749 return -ENOMEM;
750 d_add(dentry, inode);
751
752 if (sbi->version < 5)
753 autofs_set_leaf_automount_flags(dentry);
754
755 dget(dentry);
756 ino->count++;
757 p_ino = autofs_dentry_ino(dentry->d_parent);
758 p_ino->count++;
759 inc_nlink(dir);
760 dir->i_mtime = current_time(dir);
761
762 return 0;
763}
764
765/* Get/set timeout ioctl() operation */
766#ifdef CONFIG_COMPAT
767static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
768 compat_ulong_t __user *p)
769{
770 unsigned long ntimeout;
771 int rv;
772
773 rv = get_user(ntimeout, p);
774 if (rv)
775 goto error;
776
777 rv = put_user(sbi->exp_timeout/HZ, p);
778 if (rv)
779 goto error;
780
781 if (ntimeout > UINT_MAX/HZ)
782 sbi->exp_timeout = 0;
783 else
784 sbi->exp_timeout = ntimeout * HZ;
785
786 return 0;
787error:
788 return rv;
789}
790#endif
791
792static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
793 unsigned long __user *p)
794{
795 unsigned long ntimeout;
796 int rv;
797
798 rv = get_user(ntimeout, p);
799 if (rv)
800 goto error;
801
802 rv = put_user(sbi->exp_timeout/HZ, p);
803 if (rv)
804 goto error;
805
806 if (ntimeout > ULONG_MAX/HZ)
807 sbi->exp_timeout = 0;
808 else
809 sbi->exp_timeout = ntimeout * HZ;
810
811 return 0;
812error:
813 return rv;
814}
815
816/* Return protocol version */
817static inline int autofs_get_protover(struct autofs_sb_info *sbi,
818 int __user *p)
819{
820 return put_user(sbi->version, p);
821}
822
823/* Return protocol sub version */
824static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
825 int __user *p)
826{
827 return put_user(sbi->sub_version, p);
828}
829
830/*
831* Tells the daemon whether it can umount the autofs mount.
832*/
833static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
834{
835 int status = 0;
836
837 if (may_umount(mnt))
838 status = 1;
839
840 pr_debug("may umount %d\n", status);
841
842 status = put_user(status, p);
843
844 return status;
845}
846
847/* Identify autofs_dentries - this is so we can tell if there's
848 * an extra dentry refcount or not. We only hold a refcount on the
849 * dentry if its non-negative (ie, d_inode != NULL)
850 */
851int is_autofs_dentry(struct dentry *dentry)
852{
853 return dentry && d_really_is_positive(dentry) &&
854 dentry->d_op == &autofs_dentry_operations &&
855 dentry->d_fsdata != NULL;
856}
857
858/*
859 * ioctl()'s on the root directory is the chief method for the daemon to
860 * generate kernel reactions
861 */
862static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
863 unsigned int cmd, unsigned long arg)
864{
865 struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
866 void __user *p = (void __user *)arg;
867
868 pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
869 cmd, arg, sbi, task_pgrp_nr(current));
870
871 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
872 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
873 return -ENOTTY;
874
875 if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
876 return -EPERM;
877
878 switch (cmd) {
879 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
880 return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
881 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
882 return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
883 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
884 autofs_catatonic_mode(sbi);
885 return 0;
886 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
887 return autofs_get_protover(sbi, p);
888 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
889 return autofs_get_protosubver(sbi, p);
890 case AUTOFS_IOC_SETTIMEOUT:
891 return autofs_get_set_timeout(sbi, p);
892#ifdef CONFIG_COMPAT
893 case AUTOFS_IOC_SETTIMEOUT32:
894 return autofs_compat_get_set_timeout(sbi, p);
895#endif
896
897 case AUTOFS_IOC_ASKUMOUNT:
898 return autofs_ask_umount(filp->f_path.mnt, p);
899
900 /* return a single thing to expire */
901 case AUTOFS_IOC_EXPIRE:
902 return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
903 /* same as above, but can send multiple expires through pipe */
904 case AUTOFS_IOC_EXPIRE_MULTI:
905 return autofs_expire_multi(inode->i_sb,
906 filp->f_path.mnt, sbi, p);
907
908 default:
909 return -EINVAL;
910 }
911}
912
913static long autofs_root_ioctl(struct file *filp,
914 unsigned int cmd, unsigned long arg)
915{
916 struct inode *inode = file_inode(filp);
917
918 return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
919}
920
921#ifdef CONFIG_COMPAT
922static long autofs_root_compat_ioctl(struct file *filp,
923 unsigned int cmd, unsigned long arg)
924{
925 struct inode *inode = file_inode(filp);
926 int ret;
927
928 if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
929 ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
930 else
931 ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
932 (unsigned long) compat_ptr(arg));
933
934 return ret;
935}
936#endif