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d6910058 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
ebc921ca IK |
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> | |
ebc921ca IK |
6 | */ |
7 | ||
8 | #include <linux/capability.h> | |
ebc921ca | 9 | #include <linux/compat.h> |
ebc921ca IK |
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 | ||
ebc921ca IK |
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); | |
c4931db9 AV |
69 | spin_lock(&sbi->lookup_lock); |
70 | list_del_init(&ino->active); | |
71 | spin_unlock(&sbi->lookup_lock); | |
ebc921ca IK |
72 | } |
73 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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); | |
f5162216 IK |
252 | ino->last_used = jiffies; |
253 | return status; | |
ebc921ca | 254 | } |
f5162216 IK |
255 | if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE)) |
256 | ino->last_used = jiffies; | |
ebc921ca IK |
257 | return status; |
258 | } | |
259 | ||
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 | ||
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 | ||
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 | ||
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 */ | |
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", | |
9d8719a4 IK |
490 | current->pid, task_pgrp_nr(current), |
491 | sbi->flags & AUTOFS_SBI_CATATONIC, | |
ebc921ca IK |
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 | ||
ebc921ca IK |
507 | ino = autofs_new_ino(sbi); |
508 | if (!ino) | |
509 | return ERR_PTR(-ENOMEM); | |
510 | ||
5f68056c AV |
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); | |
ebc921ca IK |
517 | dentry->d_fsdata = ino; |
518 | ino->dentry = dentry; | |
519 | ||
c4931db9 AV |
520 | list_add(&ino->active, &sbi->active_list); |
521 | spin_unlock(&sbi->lookup_lock); | |
5f68056c | 522 | spin_unlock(&dentry->d_lock); |
ebc921ca IK |
523 | } |
524 | return NULL; | |
525 | } | |
526 | ||
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 | ||
d4d79b81 IK |
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 | */ | |
9d8719a4 | 547 | if (sbi->flags & AUTOFS_SBI_CATATONIC) |
d4d79b81 IK |
548 | return -EACCES; |
549 | ||
ebc921ca IK |
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); | |
850d71ac | 572 | ino->count++; |
ebc921ca | 573 | p_ino = autofs_dentry_ino(dentry->d_parent); |
850d71ac | 574 | p_ino->count++; |
ebc921ca IK |
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 | */ | |
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 | ||
d4d79b81 IK |
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 | */ | |
9d8719a4 | 609 | if (sbi->flags & AUTOFS_SBI_CATATONIC) |
d4d79b81 | 610 | return -EACCES; |
ebc921ca | 611 | |
850d71ac | 612 | ino->count--; |
41ca1974 | 613 | p_ino = autofs_dentry_ino(dentry->d_parent); |
850d71ac | 614 | p_ino->count--; |
ebc921ca IK |
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 | */ | |
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 | ||
658 | static void autofs_clear_leaf_automount_flags(struct dentry *dentry) | |
659 | { | |
ebc921ca IK |
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; | |
850d71ac | 672 | if (autofs_dentry_ino(parent)->count == 2) |
ebc921ca IK |
673 | managed_dentry_set_managed(parent); |
674 | } | |
675 | ||
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 | ||
d4d79b81 IK |
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 | */ | |
9d8719a4 | 691 | if (sbi->flags & AUTOFS_SBI_CATATONIC) |
d4d79b81 IK |
692 | return -EACCES; |
693 | ||
850d71ac | 694 | if (ino->count != 1) |
ebc921ca | 695 | return -ENOTEMPTY; |
c3aed166 AV |
696 | |
697 | spin_lock(&sbi->lookup_lock); | |
ebc921ca IK |
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 | ||
850d71ac | 705 | ino->count--; |
41ca1974 | 706 | p_ino = autofs_dentry_ino(dentry->d_parent); |
850d71ac | 707 | p_ino->count--; |
ebc921ca IK |
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 | ||
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 | ||
d4d79b81 IK |
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 | */ | |
9d8719a4 | 733 | if (sbi->flags & AUTOFS_SBI_CATATONIC) |
d4d79b81 IK |
734 | return -EACCES; |
735 | ||
ebc921ca IK |
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); | |
850d71ac | 753 | ino->count++; |
ebc921ca | 754 | p_ino = autofs_dentry_ino(dentry->d_parent); |
850d71ac | 755 | p_ino->count++; |
ebc921ca IK |
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 | |
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 | ||
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 */ | |
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 */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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 | ||
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 | |
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 |