1 /* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/root.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
7 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
8 *
9 * This file is part of the Linux kernel and is made available under
10 * the terms of the GNU General Public License, version 2, or at your
11 * option, any later version, incorporated herein by reference.
12 *
13 * ------------------------------------------------------------------------- */
14
15 #include <linux/capability.h>
16 #include <linux/errno.h>
17 #include <linux/stat.h>
18 #include <linux/param.h>
19 #include <linux/time.h>
20 #include "autofs_i.h"
21
22 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
23 static int autofs4_dir_unlink(struct inode *,struct dentry *);
24 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
25 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
27 static int autofs4_dir_open(struct inode *inode, struct file *file);
28 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
29 static void *autofs4_follow_link(struct dentry *, struct nameidata *);
30
31 #define TRIGGER_FLAGS (LOOKUP_CONTINUE | LOOKUP_DIRECTORY)
32 #define TRIGGER_INTENTS (LOOKUP_OPEN | LOOKUP_CREATE)
33
34 const struct file_operations autofs4_root_operations = {
35 .open = dcache_dir_open,
36 .release = dcache_dir_close,
37 .read = generic_read_dir,
38 .readdir = dcache_readdir,
39 .llseek = dcache_dir_lseek,
40 .ioctl = autofs4_root_ioctl,
41 };
42
43 const struct file_operations autofs4_dir_operations = {
44 .open = autofs4_dir_open,
45 .release = dcache_dir_close,
46 .read = generic_read_dir,
47 .readdir = dcache_readdir,
48 .llseek = dcache_dir_lseek,
49 };
50
51 const struct inode_operations autofs4_indirect_root_inode_operations = {
52 .lookup = autofs4_lookup,
53 .unlink = autofs4_dir_unlink,
54 .symlink = autofs4_dir_symlink,
55 .mkdir = autofs4_dir_mkdir,
56 .rmdir = autofs4_dir_rmdir,
57 };
58
59 const struct inode_operations autofs4_direct_root_inode_operations = {
60 .lookup = autofs4_lookup,
61 .unlink = autofs4_dir_unlink,
62 .mkdir = autofs4_dir_mkdir,
63 .rmdir = autofs4_dir_rmdir,
64 .follow_link = autofs4_follow_link,
65 };
66
67 const struct inode_operations autofs4_dir_inode_operations = {
68 .lookup = autofs4_lookup,
69 .unlink = autofs4_dir_unlink,
70 .symlink = autofs4_dir_symlink,
71 .mkdir = autofs4_dir_mkdir,
72 .rmdir = autofs4_dir_rmdir,
73 };
74
autofs4_dir_open(struct inode * inode,struct file * file)75 static int autofs4_dir_open(struct inode *inode, struct file *file)
76 {
77 struct dentry *dentry = file->f_path.dentry;
78 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
79
80 DPRINTK("file=%p dentry=%p %.*s",
81 file, dentry, dentry->d_name.len, dentry->d_name.name);
82
83 if (autofs4_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(&dcache_lock);
96 if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
97 spin_unlock(&dcache_lock);
98 return -ENOENT;
99 }
100 spin_unlock(&dcache_lock);
101
102 out:
103 return dcache_dir_open(inode, file);
104 }
105
try_to_fill_dentry(struct dentry * dentry,int flags)106 static int try_to_fill_dentry(struct dentry *dentry, int flags)
107 {
108 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
109 struct autofs_info *ino = autofs4_dentry_ino(dentry);
110 int status;
111
112 DPRINTK("dentry=%p %.*s ino=%p",
113 dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode);
114
115 /*
116 * Wait for a pending mount, triggering one if there
117 * isn't one already
118 */
119 if (dentry->d_inode == NULL) {
120 DPRINTK("waiting for mount name=%.*s",
121 dentry->d_name.len, dentry->d_name.name);
122
123 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
124
125 DPRINTK("mount done status=%d", status);
126
127 /* Turn this into a real negative dentry? */
128 if (status == -ENOENT) {
129 spin_lock(&dentry->d_lock);
130 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
131 spin_unlock(&dentry->d_lock);
132 return status;
133 } else if (status) {
134 /* Return a negative dentry, but leave it "pending" */
135 return status;
136 }
137 /* Trigger mount for path component or follow link */
138 } else if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||
139 flags & (TRIGGER_FLAGS | TRIGGER_INTENTS) ||
140 current->link_count) {
141 DPRINTK("waiting for mount name=%.*s",
142 dentry->d_name.len, dentry->d_name.name);
143
144 spin_lock(&dentry->d_lock);
145 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
146 spin_unlock(&dentry->d_lock);
147 status = autofs4_wait(sbi, dentry, NFY_MOUNT);
148
149 DPRINTK("mount done status=%d", status);
150
151 if (status) {
152 spin_lock(&dentry->d_lock);
153 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
154 spin_unlock(&dentry->d_lock);
155 return status;
156 }
157 }
158
159 /* Initialize expiry counter after successful mount */
160 if (ino)
161 ino->last_used = jiffies;
162
163 spin_lock(&dentry->d_lock);
164 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
165 spin_unlock(&dentry->d_lock);
166
167 return 0;
168 }
169
170 /* For autofs direct mounts the follow link triggers the mount */
autofs4_follow_link(struct dentry * dentry,struct nameidata * nd)171 static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
172 {
173 struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
174 struct autofs_info *ino = autofs4_dentry_ino(dentry);
175 int oz_mode = autofs4_oz_mode(sbi);
176 unsigned int lookup_type;
177 int status;
178
179 DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
180 dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
181 nd->flags);
182 /*
183 * For an expire of a covered direct or offset mount we need
184 * to beeak out of follow_down() at the autofs mount trigger
185 * (d_mounted--), so we can see the expiring flag, and manage
186 * the blocking and following here until the expire is completed.
187 */
188 if (oz_mode) {
189 spin_lock(&sbi->fs_lock);
190 if (ino->flags & AUTOFS_INF_EXPIRING) {
191 spin_unlock(&sbi->fs_lock);
192 /* Follow down to our covering mount. */
193 if (!follow_down(&nd->path.mnt, &nd->path.dentry))
194 goto done;
195 goto follow;
196 }
197 spin_unlock(&sbi->fs_lock);
198 goto done;
199 }
200
201 /* If an expire request is pending everyone must wait. */
202 autofs4_expire_wait(dentry);
203
204 /* We trigger a mount for almost all flags */
205 lookup_type = nd->flags & (TRIGGER_FLAGS | TRIGGER_INTENTS);
206 if (!(lookup_type || dentry->d_flags & DCACHE_AUTOFS_PENDING))
207 goto follow;
208
209 /*
210 * If the dentry contains directories then it is an autofs
211 * multi-mount with no root mount offset. So don't try to
212 * mount it again.
213 */
214 spin_lock(&dcache_lock);
215 if (dentry->d_flags & DCACHE_AUTOFS_PENDING ||
216 (!d_mountpoint(dentry) && __simple_empty(dentry))) {
217 spin_unlock(&dcache_lock);
218
219 status = try_to_fill_dentry(dentry, 0);
220 if (status)
221 goto out_error;
222
223 goto follow;
224 }
225 spin_unlock(&dcache_lock);
226 follow:
227 /*
228 * If there is no root mount it must be an autofs
229 * multi-mount with no root offset so we don't need
230 * to follow it.
231 */
232 if (d_mountpoint(dentry)) {
233 if (!autofs4_follow_mount(&nd->path.mnt,
234 &nd->path.dentry)) {
235 status = -ENOENT;
236 goto out_error;
237 }
238 }
239
240 done:
241 return NULL;
242
243 out_error:
244 path_put(&nd->path);
245 return ERR_PTR(status);
246 }
247
248 /*
249 * Revalidate is called on every cache lookup. Some of those
250 * cache lookups may actually happen while the dentry is not
251 * yet completely filled in, and revalidate has to delay such
252 * lookups..
253 */
autofs4_revalidate(struct dentry * dentry,struct nameidata * nd)254 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
255 {
256 struct inode *dir = dentry->d_parent->d_inode;
257 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
258 int oz_mode = autofs4_oz_mode(sbi);
259 int flags = nd ? nd->flags : 0;
260 int status = 1;
261
262 /* Pending dentry */
263 spin_lock(&sbi->fs_lock);
264 if (autofs4_ispending(dentry)) {
265 /* The daemon never causes a mount to trigger */
266 spin_unlock(&sbi->fs_lock);
267
268 if (oz_mode)
269 return 1;
270
271 /*
272 * If the directory has gone away due to an expire
273 * we have been called as ->d_revalidate() and so
274 * we need to return false and proceed to ->lookup().
275 */
276 if (autofs4_expire_wait(dentry) == -EAGAIN)
277 return 0;
278
279 /*
280 * A zero status is success otherwise we have a
281 * negative error code.
282 */
283 status = try_to_fill_dentry(dentry, flags);
284 if (status == 0)
285 return 1;
286
287 return status;
288 }
289 spin_unlock(&sbi->fs_lock);
290
291 /* Negative dentry.. invalidate if "old" */
292 if (dentry->d_inode == NULL)
293 return 0;
294
295 /* Check for a non-mountpoint directory with no contents */
296 spin_lock(&dcache_lock);
297 if (S_ISDIR(dentry->d_inode->i_mode) &&
298 !d_mountpoint(dentry) &&
299 __simple_empty(dentry)) {
300 DPRINTK("dentry=%p %.*s, emptydir",
301 dentry, dentry->d_name.len, dentry->d_name.name);
302 spin_unlock(&dcache_lock);
303
304 /* The daemon never causes a mount to trigger */
305 if (oz_mode)
306 return 1;
307
308 /*
309 * A zero status is success otherwise we have a
310 * negative error code.
311 */
312 status = try_to_fill_dentry(dentry, flags);
313 if (status == 0)
314 return 1;
315
316 return status;
317 }
318 spin_unlock(&dcache_lock);
319
320 return 1;
321 }
322
autofs4_dentry_release(struct dentry * de)323 void autofs4_dentry_release(struct dentry *de)
324 {
325 struct autofs_info *inf;
326
327 DPRINTK("releasing %p", de);
328
329 inf = autofs4_dentry_ino(de);
330 de->d_fsdata = NULL;
331
332 if (inf) {
333 struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);
334
335 if (sbi) {
336 spin_lock(&sbi->lookup_lock);
337 if (!list_empty(&inf->active))
338 list_del(&inf->active);
339 if (!list_empty(&inf->expiring))
340 list_del(&inf->expiring);
341 spin_unlock(&sbi->lookup_lock);
342 }
343
344 inf->dentry = NULL;
345 inf->inode = NULL;
346
347 autofs4_free_ino(inf);
348 }
349 }
350
351 /* For dentries of directories in the root dir */
352 static struct dentry_operations autofs4_root_dentry_operations = {
353 .d_revalidate = autofs4_revalidate,
354 .d_release = autofs4_dentry_release,
355 };
356
357 /* For other dentries */
358 static struct dentry_operations autofs4_dentry_operations = {
359 .d_revalidate = autofs4_revalidate,
360 .d_release = autofs4_dentry_release,
361 };
362
autofs4_lookup_active(struct autofs_sb_info * sbi,struct dentry * parent,struct qstr * name)363 static struct dentry *autofs4_lookup_active(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
364 {
365 unsigned int len = name->len;
366 unsigned int hash = name->hash;
367 const unsigned char *str = name->name;
368 struct list_head *p, *head;
369
370 spin_lock(&dcache_lock);
371 spin_lock(&sbi->lookup_lock);
372 head = &sbi->active_list;
373 list_for_each(p, head) {
374 struct autofs_info *ino;
375 struct dentry *dentry;
376 struct qstr *qstr;
377
378 ino = list_entry(p, struct autofs_info, active);
379 dentry = ino->dentry;
380
381 spin_lock(&dentry->d_lock);
382
383 /* Already gone? */
384 if (atomic_read(&dentry->d_count) == 0)
385 goto next;
386
387 qstr = &dentry->d_name;
388
389 if (dentry->d_name.hash != hash)
390 goto next;
391 if (dentry->d_parent != parent)
392 goto next;
393
394 if (qstr->len != len)
395 goto next;
396 if (memcmp(qstr->name, str, len))
397 goto next;
398
399 if (d_unhashed(dentry)) {
400 dget(dentry);
401 spin_unlock(&dentry->d_lock);
402 spin_unlock(&sbi->lookup_lock);
403 spin_unlock(&dcache_lock);
404 return dentry;
405 }
406 next:
407 spin_unlock(&dentry->d_lock);
408 }
409 spin_unlock(&sbi->lookup_lock);
410 spin_unlock(&dcache_lock);
411
412 return NULL;
413 }
414
autofs4_lookup_expiring(struct autofs_sb_info * sbi,struct dentry * parent,struct qstr * name)415 static struct dentry *autofs4_lookup_expiring(struct autofs_sb_info *sbi, struct dentry *parent, struct qstr *name)
416 {
417 unsigned int len = name->len;
418 unsigned int hash = name->hash;
419 const unsigned char *str = name->name;
420 struct list_head *p, *head;
421
422 spin_lock(&dcache_lock);
423 spin_lock(&sbi->lookup_lock);
424 head = &sbi->expiring_list;
425 list_for_each(p, head) {
426 struct autofs_info *ino;
427 struct dentry *dentry;
428 struct qstr *qstr;
429
430 ino = list_entry(p, struct autofs_info, expiring);
431 dentry = ino->dentry;
432
433 spin_lock(&dentry->d_lock);
434
435 /* Bad luck, we've already been dentry_iput */
436 if (!dentry->d_inode)
437 goto next;
438
439 qstr = &dentry->d_name;
440
441 if (dentry->d_name.hash != hash)
442 goto next;
443 if (dentry->d_parent != parent)
444 goto next;
445
446 if (qstr->len != len)
447 goto next;
448 if (memcmp(qstr->name, str, len))
449 goto next;
450
451 if (d_unhashed(dentry)) {
452 dget(dentry);
453 spin_unlock(&dentry->d_lock);
454 spin_unlock(&sbi->lookup_lock);
455 spin_unlock(&dcache_lock);
456 return dentry;
457 }
458 next:
459 spin_unlock(&dentry->d_lock);
460 }
461 spin_unlock(&sbi->lookup_lock);
462 spin_unlock(&dcache_lock);
463
464 return NULL;
465 }
466
467 /* Lookups in the root directory */
autofs4_lookup(struct inode * dir,struct dentry * dentry,struct nameidata * nd)468 static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
469 {
470 struct autofs_sb_info *sbi;
471 struct autofs_info *ino;
472 struct dentry *expiring, *unhashed;
473 int oz_mode;
474
475 DPRINTK("name = %.*s",
476 dentry->d_name.len, dentry->d_name.name);
477
478 /* File name too long to exist */
479 if (dentry->d_name.len > NAME_MAX)
480 return ERR_PTR(-ENAMETOOLONG);
481
482 sbi = autofs4_sbi(dir->i_sb);
483 oz_mode = autofs4_oz_mode(sbi);
484
485 DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",
486 current->pid, task_pgrp_nr(current), sbi->catatonic, oz_mode);
487
488 expiring = autofs4_lookup_expiring(sbi, dentry->d_parent, &dentry->d_name);
489 if (expiring) {
490 /*
491 * If we are racing with expire the request might not
492 * be quite complete but the directory has been removed
493 * so it must have been successful, so just wait for it.
494 */
495 ino = autofs4_dentry_ino(expiring);
496 autofs4_expire_wait(expiring);
497 spin_lock(&sbi->lookup_lock);
498 if (!list_empty(&ino->expiring))
499 list_del_init(&ino->expiring);
500 spin_unlock(&sbi->lookup_lock);
501 dput(expiring);
502 }
503
504 unhashed = autofs4_lookup_active(sbi, dentry->d_parent, &dentry->d_name);
505 if (unhashed)
506 dentry = unhashed;
507 else {
508 /*
509 * Mark the dentry incomplete but don't hash it. We do this
510 * to serialize our inode creation operations (symlink and
511 * mkdir) which prevents deadlock during the callback to
512 * the daemon. Subsequent user space lookups for the same
513 * dentry are placed on the wait queue while the daemon
514 * itself is allowed passage unresticted so the create
515 * operation itself can then hash the dentry. Finally,
516 * we check for the hashed dentry and return the newly
517 * hashed dentry.
518 */
519 dentry->d_op = &autofs4_root_dentry_operations;
520
521 /*
522 * And we need to ensure that the same dentry is used for
523 * all following lookup calls until it is hashed so that
524 * the dentry flags are persistent throughout the request.
525 */
526 ino = autofs4_init_ino(NULL, sbi, 0555);
527 if (!ino)
528 return ERR_PTR(-ENOMEM);
529
530 dentry->d_fsdata = ino;
531 ino->dentry = dentry;
532
533 spin_lock(&sbi->lookup_lock);
534 list_add(&ino->active, &sbi->active_list);
535 spin_unlock(&sbi->lookup_lock);
536
537 d_instantiate(dentry, NULL);
538 }
539
540 if (!oz_mode) {
541 spin_lock(&dentry->d_lock);
542 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
543 spin_unlock(&dentry->d_lock);
544 if (dentry->d_op && dentry->d_op->d_revalidate) {
545 mutex_unlock(&dir->i_mutex);
546 (dentry->d_op->d_revalidate)(dentry, nd);
547 mutex_lock(&dir->i_mutex);
548 }
549 }
550
551 /*
552 * If we are still pending, check if we had to handle
553 * a signal. If so we can force a restart..
554 */
555 if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
556 /* See if we were interrupted */
557 if (signal_pending(current)) {
558 sigset_t *sigset = ¤t->pending.signal;
559 if (sigismember (sigset, SIGKILL) ||
560 sigismember (sigset, SIGQUIT) ||
561 sigismember (sigset, SIGINT)) {
562 if (unhashed)
563 dput(unhashed);
564 return ERR_PTR(-ERESTARTNOINTR);
565 }
566 }
567 if (!oz_mode) {
568 spin_lock(&dentry->d_lock);
569 dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
570 spin_unlock(&dentry->d_lock);
571 }
572 }
573
574 /*
575 * If this dentry is unhashed, then we shouldn't honour this
576 * lookup. Returning ENOENT here doesn't do the right thing
577 * for all system calls, but it should be OK for the operations
578 * we permit from an autofs.
579 */
580 if (!oz_mode && d_unhashed(dentry)) {
581 /*
582 * A user space application can (and has done in the past)
583 * remove and re-create this directory during the callback.
584 * This can leave us with an unhashed dentry, but a
585 * successful mount! So we need to perform another
586 * cached lookup in case the dentry now exists.
587 */
588 struct dentry *parent = dentry->d_parent;
589 struct dentry *new = d_lookup(parent, &dentry->d_name);
590 if (new != NULL)
591 dentry = new;
592 else
593 dentry = ERR_PTR(-ENOENT);
594
595 if (unhashed)
596 dput(unhashed);
597
598 return dentry;
599 }
600
601 if (unhashed)
602 return unhashed;
603
604 return NULL;
605 }
606
autofs4_dir_symlink(struct inode * dir,struct dentry * dentry,const char * symname)607 static int autofs4_dir_symlink(struct inode *dir,
608 struct dentry *dentry,
609 const char *symname)
610 {
611 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
612 struct autofs_info *ino = autofs4_dentry_ino(dentry);
613 struct autofs_info *p_ino;
614 struct inode *inode;
615 char *cp;
616
617 DPRINTK("%s <- %.*s", symname,
618 dentry->d_name.len, dentry->d_name.name);
619
620 if (!autofs4_oz_mode(sbi))
621 return -EACCES;
622
623 ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
624 if (!ino)
625 return -ENOMEM;
626
627 spin_lock(&sbi->lookup_lock);
628 if (!list_empty(&ino->active))
629 list_del_init(&ino->active);
630 spin_unlock(&sbi->lookup_lock);
631
632 ino->size = strlen(symname);
633 cp = kmalloc(ino->size + 1, GFP_KERNEL);
634 if (!cp) {
635 if (!dentry->d_fsdata)
636 kfree(ino);
637 return -ENOMEM;
638 }
639
640 strcpy(cp, symname);
641
642 inode = autofs4_get_inode(dir->i_sb, ino);
643 if (!inode) {
644 kfree(cp);
645 if (!dentry->d_fsdata)
646 kfree(ino);
647 return -ENOMEM;
648 }
649 d_add(dentry, inode);
650
651 if (dir == dir->i_sb->s_root->d_inode)
652 dentry->d_op = &autofs4_root_dentry_operations;
653 else
654 dentry->d_op = &autofs4_dentry_operations;
655
656 dentry->d_fsdata = ino;
657 ino->dentry = dget(dentry);
658 atomic_inc(&ino->count);
659 p_ino = autofs4_dentry_ino(dentry->d_parent);
660 if (p_ino && dentry->d_parent != dentry)
661 atomic_inc(&p_ino->count);
662 ino->inode = inode;
663
664 ino->u.symlink = cp;
665 dir->i_mtime = CURRENT_TIME;
666
667 return 0;
668 }
669
670 /*
671 * NOTE!
672 *
673 * Normal filesystems would do a "d_delete()" to tell the VFS dcache
674 * that the file no longer exists. However, doing that means that the
675 * VFS layer can turn the dentry into a negative dentry. We don't want
676 * this, because the unlink is probably the result of an expire.
677 * We simply d_drop it and add it to a expiring list in the super block,
678 * which allows the dentry lookup to check for an incomplete expire.
679 *
680 * If a process is blocked on the dentry waiting for the expire to finish,
681 * it will invalidate the dentry and try to mount with a new one.
682 *
683 * Also see autofs4_dir_rmdir()..
684 */
autofs4_dir_unlink(struct inode * dir,struct dentry * dentry)685 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
686 {
687 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
688 struct autofs_info *ino = autofs4_dentry_ino(dentry);
689 struct autofs_info *p_ino;
690
691 /* This allows root to remove symlinks */
692 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
693 return -EACCES;
694
695 if (atomic_dec_and_test(&ino->count)) {
696 p_ino = autofs4_dentry_ino(dentry->d_parent);
697 if (p_ino && dentry->d_parent != dentry)
698 atomic_dec(&p_ino->count);
699 }
700 dput(ino->dentry);
701
702 dentry->d_inode->i_size = 0;
703 clear_nlink(dentry->d_inode);
704
705 dir->i_mtime = CURRENT_TIME;
706
707 spin_lock(&dcache_lock);
708 spin_lock(&sbi->lookup_lock);
709 if (list_empty(&ino->expiring))
710 list_add(&ino->expiring, &sbi->expiring_list);
711 spin_unlock(&sbi->lookup_lock);
712 spin_lock(&dentry->d_lock);
713 __d_drop(dentry);
714 spin_unlock(&dentry->d_lock);
715 spin_unlock(&dcache_lock);
716
717 return 0;
718 }
719
autofs4_dir_rmdir(struct inode * dir,struct dentry * dentry)720 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
721 {
722 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
723 struct autofs_info *ino = autofs4_dentry_ino(dentry);
724 struct autofs_info *p_ino;
725
726 DPRINTK("dentry %p, removing %.*s",
727 dentry, dentry->d_name.len, dentry->d_name.name);
728
729 if (!autofs4_oz_mode(sbi))
730 return -EACCES;
731
732 spin_lock(&dcache_lock);
733 if (!list_empty(&dentry->d_subdirs)) {
734 spin_unlock(&dcache_lock);
735 return -ENOTEMPTY;
736 }
737 spin_lock(&sbi->lookup_lock);
738 if (list_empty(&ino->expiring))
739 list_add(&ino->expiring, &sbi->expiring_list);
740 spin_unlock(&sbi->lookup_lock);
741 spin_lock(&dentry->d_lock);
742 __d_drop(dentry);
743 spin_unlock(&dentry->d_lock);
744 spin_unlock(&dcache_lock);
745
746 if (atomic_dec_and_test(&ino->count)) {
747 p_ino = autofs4_dentry_ino(dentry->d_parent);
748 if (p_ino && dentry->d_parent != dentry)
749 atomic_dec(&p_ino->count);
750 }
751 dput(ino->dentry);
752 dentry->d_inode->i_size = 0;
753 clear_nlink(dentry->d_inode);
754
755 if (dir->i_nlink)
756 drop_nlink(dir);
757
758 return 0;
759 }
760
autofs4_dir_mkdir(struct inode * dir,struct dentry * dentry,int mode)761 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
762 {
763 struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
764 struct autofs_info *ino = autofs4_dentry_ino(dentry);
765 struct autofs_info *p_ino;
766 struct inode *inode;
767
768 if (!autofs4_oz_mode(sbi))
769 return -EACCES;
770
771 DPRINTK("dentry %p, creating %.*s",
772 dentry, dentry->d_name.len, dentry->d_name.name);
773
774 ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
775 if (!ino)
776 return -ENOMEM;
777
778 spin_lock(&sbi->lookup_lock);
779 if (!list_empty(&ino->active))
780 list_del_init(&ino->active);
781 spin_unlock(&sbi->lookup_lock);
782
783 inode = autofs4_get_inode(dir->i_sb, ino);
784 if (!inode) {
785 if (!dentry->d_fsdata)
786 kfree(ino);
787 return -ENOMEM;
788 }
789 d_add(dentry, inode);
790
791 if (dir == dir->i_sb->s_root->d_inode)
792 dentry->d_op = &autofs4_root_dentry_operations;
793 else
794 dentry->d_op = &autofs4_dentry_operations;
795
796 dentry->d_fsdata = ino;
797 ino->dentry = dget(dentry);
798 atomic_inc(&ino->count);
799 p_ino = autofs4_dentry_ino(dentry->d_parent);
800 if (p_ino && dentry->d_parent != dentry)
801 atomic_inc(&p_ino->count);
802 ino->inode = inode;
803 inc_nlink(dir);
804 dir->i_mtime = CURRENT_TIME;
805
806 return 0;
807 }
808
809 /* Get/set timeout ioctl() operation */
autofs4_get_set_timeout(struct autofs_sb_info * sbi,unsigned long __user * p)810 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
811 unsigned long __user *p)
812 {
813 int rv;
814 unsigned long ntimeout;
815
816 if ((rv = get_user(ntimeout, p)) ||
817 (rv = put_user(sbi->exp_timeout/HZ, p)))
818 return rv;
819
820 if (ntimeout > ULONG_MAX/HZ)
821 sbi->exp_timeout = 0;
822 else
823 sbi->exp_timeout = ntimeout * HZ;
824
825 return 0;
826 }
827
828 /* Return protocol version */
autofs4_get_protover(struct autofs_sb_info * sbi,int __user * p)829 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
830 {
831 return put_user(sbi->version, p);
832 }
833
834 /* Return protocol sub version */
autofs4_get_protosubver(struct autofs_sb_info * sbi,int __user * p)835 static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
836 {
837 return put_user(sbi->sub_version, p);
838 }
839
840 /*
841 * Tells the daemon whether it can umount the autofs mount.
842 */
autofs4_ask_umount(struct vfsmount * mnt,int __user * p)843 static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
844 {
845 int status = 0;
846
847 if (may_umount(mnt))
848 status = 1;
849
850 DPRINTK("returning %d", status);
851
852 status = put_user(status, p);
853
854 return status;
855 }
856
857 /* Identify autofs4_dentries - this is so we can tell if there's
858 an extra dentry refcount or not. We only hold a refcount on the
859 dentry if its non-negative (ie, d_inode != NULL)
860 */
is_autofs4_dentry(struct dentry * dentry)861 int is_autofs4_dentry(struct dentry *dentry)
862 {
863 return dentry && dentry->d_inode &&
864 (dentry->d_op == &autofs4_root_dentry_operations ||
865 dentry->d_op == &autofs4_dentry_operations) &&
866 dentry->d_fsdata != NULL;
867 }
868
869 /*
870 * ioctl()'s on the root directory is the chief method for the daemon to
871 * generate kernel reactions
872 */
autofs4_root_ioctl(struct inode * inode,struct file * filp,unsigned int cmd,unsigned long arg)873 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
874 unsigned int cmd, unsigned long arg)
875 {
876 struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
877 void __user *p = (void __user *)arg;
878
879 DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",
880 cmd,arg,sbi,task_pgrp_nr(current));
881
882 if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
883 _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
884 return -ENOTTY;
885
886 if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
887 return -EPERM;
888
889 switch(cmd) {
890 case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
891 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
892 case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
893 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
894 case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
895 autofs4_catatonic_mode(sbi);
896 return 0;
897 case AUTOFS_IOC_PROTOVER: /* Get protocol version */
898 return autofs4_get_protover(sbi, p);
899 case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
900 return autofs4_get_protosubver(sbi, p);
901 case AUTOFS_IOC_SETTIMEOUT:
902 return autofs4_get_set_timeout(sbi, p);
903
904 case AUTOFS_IOC_ASKUMOUNT:
905 return autofs4_ask_umount(filp->f_path.mnt, p);
906
907 /* return a single thing to expire */
908 case AUTOFS_IOC_EXPIRE:
909 return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);
910 /* same as above, but can send multiple expires through pipe */
911 case AUTOFS_IOC_EXPIRE_MULTI:
912 return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);
913
914 default:
915 return -ENOSYS;
916 }
917 }
918