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1 | /* | |
2 | * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved | |
3 | * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org> | |
4 | * Copyright 2001-2006 Ian Kent <raven@themaw.net> | |
5 | * | |
6 | * This file is part of the Linux kernel and is made available under | |
7 | * the terms of the GNU General Public License, version 2, or at your | |
8 | * option, any later version, incorporated herein by reference. | |
9 | */ | |
10 | ||
11 | #include <linux/capability.h> | |
12 | #include <linux/errno.h> | |
13 | #include <linux/stat.h> | |
14 | #include <linux/slab.h> | |
15 | #include <linux/param.h> | |
16 | #include <linux/time.h> | |
17 | #include <linux/compat.h> | |
18 | #include <linux/mutex.h> | |
19 | ||
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 *, umode_t); | |
26 | static long autofs4_root_ioctl(struct file *, unsigned int, unsigned long); | |
27 | #ifdef CONFIG_COMPAT | |
28 | static long autofs4_root_compat_ioctl(struct file *, | |
29 | unsigned int, unsigned long); | |
30 | #endif | |
31 | static int autofs4_dir_open(struct inode *inode, struct file *file); | |
32 | static struct dentry *autofs4_lookup(struct inode *, | |
33 | struct dentry *, unsigned int); | |
34 | static struct vfsmount *autofs4_d_automount(struct path *); | |
35 | static int autofs4_d_manage(const struct path *, bool); | |
36 | static void autofs4_dentry_release(struct dentry *); | |
37 | ||
38 | const struct file_operations autofs4_root_operations = { | |
39 | .open = dcache_dir_open, | |
40 | .release = dcache_dir_close, | |
41 | .read = generic_read_dir, | |
42 | .iterate_shared = dcache_readdir, | |
43 | .llseek = dcache_dir_lseek, | |
44 | .unlocked_ioctl = autofs4_root_ioctl, | |
45 | #ifdef CONFIG_COMPAT | |
46 | .compat_ioctl = autofs4_root_compat_ioctl, | |
47 | #endif | |
48 | }; | |
49 | ||
50 | const struct file_operations autofs4_dir_operations = { | |
51 | .open = autofs4_dir_open, | |
52 | .release = dcache_dir_close, | |
53 | .read = generic_read_dir, | |
54 | .iterate_shared = dcache_readdir, | |
55 | .llseek = dcache_dir_lseek, | |
56 | }; | |
57 | ||
58 | const struct inode_operations autofs4_dir_inode_operations = { | |
59 | .lookup = autofs4_lookup, | |
60 | .unlink = autofs4_dir_unlink, | |
61 | .symlink = autofs4_dir_symlink, | |
62 | .mkdir = autofs4_dir_mkdir, | |
63 | .rmdir = autofs4_dir_rmdir, | |
64 | }; | |
65 | ||
66 | const struct dentry_operations autofs4_dentry_operations = { | |
67 | .d_automount = autofs4_d_automount, | |
68 | .d_manage = autofs4_d_manage, | |
69 | .d_release = autofs4_dentry_release, | |
70 | }; | |
71 | ||
72 | static void autofs4_add_active(struct dentry *dentry) | |
73 | { | |
74 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
75 | struct autofs_info *ino; | |
76 | ||
77 | ino = autofs4_dentry_ino(dentry); | |
78 | if (ino) { | |
79 | spin_lock(&sbi->lookup_lock); | |
80 | if (!ino->active_count) { | |
81 | if (list_empty(&ino->active)) | |
82 | list_add(&ino->active, &sbi->active_list); | |
83 | } | |
84 | ino->active_count++; | |
85 | spin_unlock(&sbi->lookup_lock); | |
86 | } | |
87 | } | |
88 | ||
89 | static void autofs4_del_active(struct dentry *dentry) | |
90 | { | |
91 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
92 | struct autofs_info *ino; | |
93 | ||
94 | ino = autofs4_dentry_ino(dentry); | |
95 | if (ino) { | |
96 | spin_lock(&sbi->lookup_lock); | |
97 | ino->active_count--; | |
98 | if (!ino->active_count) { | |
99 | if (!list_empty(&ino->active)) | |
100 | list_del_init(&ino->active); | |
101 | } | |
102 | spin_unlock(&sbi->lookup_lock); | |
103 | } | |
104 | } | |
105 | ||
106 | static int autofs4_dir_open(struct inode *inode, struct file *file) | |
107 | { | |
108 | struct dentry *dentry = file->f_path.dentry; | |
109 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
110 | ||
111 | pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry); | |
112 | ||
113 | if (autofs4_oz_mode(sbi)) | |
114 | goto out; | |
115 | ||
116 | /* | |
117 | * An empty directory in an autofs file system is always a | |
118 | * mount point. The daemon must have failed to mount this | |
119 | * during lookup so it doesn't exist. This can happen, for | |
120 | * example, if user space returns an incorrect status for a | |
121 | * mount request. Otherwise we're doing a readdir on the | |
122 | * autofs file system so just let the libfs routines handle | |
123 | * it. | |
124 | */ | |
125 | spin_lock(&sbi->lookup_lock); | |
126 | if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) { | |
127 | spin_unlock(&sbi->lookup_lock); | |
128 | return -ENOENT; | |
129 | } | |
130 | spin_unlock(&sbi->lookup_lock); | |
131 | ||
132 | out: | |
133 | return dcache_dir_open(inode, file); | |
134 | } | |
135 | ||
136 | static void autofs4_dentry_release(struct dentry *de) | |
137 | { | |
138 | struct autofs_info *ino = autofs4_dentry_ino(de); | |
139 | struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb); | |
140 | ||
141 | pr_debug("releasing %p\n", de); | |
142 | ||
143 | if (!ino) | |
144 | return; | |
145 | ||
146 | if (sbi) { | |
147 | spin_lock(&sbi->lookup_lock); | |
148 | if (!list_empty(&ino->active)) | |
149 | list_del(&ino->active); | |
150 | if (!list_empty(&ino->expiring)) | |
151 | list_del(&ino->expiring); | |
152 | spin_unlock(&sbi->lookup_lock); | |
153 | } | |
154 | ||
155 | autofs4_free_ino(ino); | |
156 | } | |
157 | ||
158 | static struct dentry *autofs4_lookup_active(struct dentry *dentry) | |
159 | { | |
160 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
161 | struct dentry *parent = dentry->d_parent; | |
162 | const struct qstr *name = &dentry->d_name; | |
163 | unsigned int len = name->len; | |
164 | unsigned int hash = name->hash; | |
165 | const unsigned char *str = name->name; | |
166 | struct list_head *p, *head; | |
167 | ||
168 | head = &sbi->active_list; | |
169 | if (list_empty(head)) | |
170 | return NULL; | |
171 | spin_lock(&sbi->lookup_lock); | |
172 | list_for_each(p, head) { | |
173 | struct autofs_info *ino; | |
174 | struct dentry *active; | |
175 | const struct qstr *qstr; | |
176 | ||
177 | ino = list_entry(p, struct autofs_info, active); | |
178 | active = ino->dentry; | |
179 | ||
180 | spin_lock(&active->d_lock); | |
181 | ||
182 | /* Already gone? */ | |
183 | if ((int) d_count(active) <= 0) | |
184 | goto next; | |
185 | ||
186 | qstr = &active->d_name; | |
187 | ||
188 | if (active->d_name.hash != hash) | |
189 | goto next; | |
190 | if (active->d_parent != parent) | |
191 | goto next; | |
192 | ||
193 | if (qstr->len != len) | |
194 | goto next; | |
195 | if (memcmp(qstr->name, str, len)) | |
196 | goto next; | |
197 | ||
198 | if (d_unhashed(active)) { | |
199 | dget_dlock(active); | |
200 | spin_unlock(&active->d_lock); | |
201 | spin_unlock(&sbi->lookup_lock); | |
202 | return active; | |
203 | } | |
204 | next: | |
205 | spin_unlock(&active->d_lock); | |
206 | } | |
207 | spin_unlock(&sbi->lookup_lock); | |
208 | ||
209 | return NULL; | |
210 | } | |
211 | ||
212 | static struct dentry *autofs4_lookup_expiring(struct dentry *dentry, | |
213 | bool rcu_walk) | |
214 | { | |
215 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
216 | struct dentry *parent = dentry->d_parent; | |
217 | const struct qstr *name = &dentry->d_name; | |
218 | unsigned int len = name->len; | |
219 | unsigned int hash = name->hash; | |
220 | const unsigned char *str = name->name; | |
221 | struct list_head *p, *head; | |
222 | ||
223 | head = &sbi->expiring_list; | |
224 | if (list_empty(head)) | |
225 | return NULL; | |
226 | spin_lock(&sbi->lookup_lock); | |
227 | list_for_each(p, head) { | |
228 | struct autofs_info *ino; | |
229 | struct dentry *expiring; | |
230 | const struct qstr *qstr; | |
231 | ||
232 | if (rcu_walk) { | |
233 | spin_unlock(&sbi->lookup_lock); | |
234 | return ERR_PTR(-ECHILD); | |
235 | } | |
236 | ||
237 | ino = list_entry(p, struct autofs_info, expiring); | |
238 | expiring = ino->dentry; | |
239 | ||
240 | spin_lock(&expiring->d_lock); | |
241 | ||
242 | /* We've already been dentry_iput or unlinked */ | |
243 | if (d_really_is_negative(expiring)) | |
244 | goto next; | |
245 | ||
246 | qstr = &expiring->d_name; | |
247 | ||
248 | if (expiring->d_name.hash != hash) | |
249 | goto next; | |
250 | if (expiring->d_parent != parent) | |
251 | goto next; | |
252 | ||
253 | if (qstr->len != len) | |
254 | goto next; | |
255 | if (memcmp(qstr->name, str, len)) | |
256 | goto next; | |
257 | ||
258 | if (d_unhashed(expiring)) { | |
259 | dget_dlock(expiring); | |
260 | spin_unlock(&expiring->d_lock); | |
261 | spin_unlock(&sbi->lookup_lock); | |
262 | return expiring; | |
263 | } | |
264 | next: | |
265 | spin_unlock(&expiring->d_lock); | |
266 | } | |
267 | spin_unlock(&sbi->lookup_lock); | |
268 | ||
269 | return NULL; | |
270 | } | |
271 | ||
272 | static int autofs4_mount_wait(const struct path *path, bool rcu_walk) | |
273 | { | |
274 | struct autofs_sb_info *sbi = autofs4_sbi(path->dentry->d_sb); | |
275 | struct autofs_info *ino = autofs4_dentry_ino(path->dentry); | |
276 | int status = 0; | |
277 | ||
278 | if (ino->flags & AUTOFS_INF_PENDING) { | |
279 | if (rcu_walk) | |
280 | return -ECHILD; | |
281 | pr_debug("waiting for mount name=%pd\n", path->dentry); | |
282 | status = autofs4_wait(sbi, path, NFY_MOUNT); | |
283 | pr_debug("mount wait done status=%d\n", status); | |
284 | } | |
285 | ino->last_used = jiffies; | |
286 | return status; | |
287 | } | |
288 | ||
289 | static int do_expire_wait(const struct path *path, bool rcu_walk) | |
290 | { | |
291 | struct dentry *dentry = path->dentry; | |
292 | struct dentry *expiring; | |
293 | ||
294 | expiring = autofs4_lookup_expiring(dentry, rcu_walk); | |
295 | if (IS_ERR(expiring)) | |
296 | return PTR_ERR(expiring); | |
297 | if (!expiring) | |
298 | return autofs4_expire_wait(path, rcu_walk); | |
299 | else { | |
300 | const struct path this = { .mnt = path->mnt, .dentry = expiring }; | |
301 | /* | |
302 | * If we are racing with expire the request might not | |
303 | * be quite complete, but the directory has been removed | |
304 | * so it must have been successful, just wait for it. | |
305 | */ | |
306 | autofs4_expire_wait(&this, 0); | |
307 | autofs4_del_expiring(expiring); | |
308 | dput(expiring); | |
309 | } | |
310 | return 0; | |
311 | } | |
312 | ||
313 | static struct dentry *autofs4_mountpoint_changed(struct path *path) | |
314 | { | |
315 | struct dentry *dentry = path->dentry; | |
316 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
317 | ||
318 | /* | |
319 | * If this is an indirect mount the dentry could have gone away | |
320 | * as a result of an expire and a new one created. | |
321 | */ | |
322 | if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) { | |
323 | struct dentry *parent = dentry->d_parent; | |
324 | struct autofs_info *ino; | |
325 | struct dentry *new; | |
326 | ||
327 | new = d_lookup(parent, &dentry->d_name); | |
328 | if (!new) | |
329 | return NULL; | |
330 | ino = autofs4_dentry_ino(new); | |
331 | ino->last_used = jiffies; | |
332 | dput(path->dentry); | |
333 | path->dentry = new; | |
334 | } | |
335 | return path->dentry; | |
336 | } | |
337 | ||
338 | static struct vfsmount *autofs4_d_automount(struct path *path) | |
339 | { | |
340 | struct dentry *dentry = path->dentry; | |
341 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
342 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
343 | int status; | |
344 | ||
345 | pr_debug("dentry=%p %pd\n", dentry, dentry); | |
346 | ||
347 | /* The daemon never triggers a mount. */ | |
348 | if (autofs4_oz_mode(sbi)) | |
349 | return NULL; | |
350 | ||
351 | /* | |
352 | * If an expire request is pending everyone must wait. | |
353 | * If the expire fails we're still mounted so continue | |
354 | * the follow and return. A return of -EAGAIN (which only | |
355 | * happens with indirect mounts) means the expire completed | |
356 | * and the directory was removed, so just go ahead and try | |
357 | * the mount. | |
358 | */ | |
359 | status = do_expire_wait(path, 0); | |
360 | if (status && status != -EAGAIN) | |
361 | return NULL; | |
362 | ||
363 | /* Callback to the daemon to perform the mount or wait */ | |
364 | spin_lock(&sbi->fs_lock); | |
365 | if (ino->flags & AUTOFS_INF_PENDING) { | |
366 | spin_unlock(&sbi->fs_lock); | |
367 | status = autofs4_mount_wait(path, 0); | |
368 | if (status) | |
369 | return ERR_PTR(status); | |
370 | goto done; | |
371 | } | |
372 | ||
373 | /* | |
374 | * If the dentry is a symlink it's equivalent to a directory | |
375 | * having path_is_mountpoint() true, so there's no need to call | |
376 | * back to the daemon. | |
377 | */ | |
378 | if (d_really_is_positive(dentry) && d_is_symlink(dentry)) { | |
379 | spin_unlock(&sbi->fs_lock); | |
380 | goto done; | |
381 | } | |
382 | ||
383 | if (!path_is_mountpoint(path)) { | |
384 | /* | |
385 | * It's possible that user space hasn't removed directories | |
386 | * after umounting a rootless multi-mount, although it | |
387 | * should. For v5 path_has_submounts() is sufficient to | |
388 | * handle this because the leaves of the directory tree under | |
389 | * the mount never trigger mounts themselves (they have an | |
390 | * autofs trigger mount mounted on them). But v4 pseudo direct | |
391 | * mounts do need the leaves to trigger mounts. In this case | |
392 | * we have no choice but to use the list_empty() check and | |
393 | * require user space behave. | |
394 | */ | |
395 | if (sbi->version > 4) { | |
396 | if (path_has_submounts(path)) { | |
397 | spin_unlock(&sbi->fs_lock); | |
398 | goto done; | |
399 | } | |
400 | } else { | |
401 | if (!simple_empty(dentry)) { | |
402 | spin_unlock(&sbi->fs_lock); | |
403 | goto done; | |
404 | } | |
405 | } | |
406 | ino->flags |= AUTOFS_INF_PENDING; | |
407 | spin_unlock(&sbi->fs_lock); | |
408 | status = autofs4_mount_wait(path, 0); | |
409 | spin_lock(&sbi->fs_lock); | |
410 | ino->flags &= ~AUTOFS_INF_PENDING; | |
411 | if (status) { | |
412 | spin_unlock(&sbi->fs_lock); | |
413 | return ERR_PTR(status); | |
414 | } | |
415 | } | |
416 | spin_unlock(&sbi->fs_lock); | |
417 | done: | |
418 | /* Mount succeeded, check if we ended up with a new dentry */ | |
419 | dentry = autofs4_mountpoint_changed(path); | |
420 | if (!dentry) | |
421 | return ERR_PTR(-ENOENT); | |
422 | ||
423 | return NULL; | |
424 | } | |
425 | ||
426 | static int autofs4_d_manage(const struct path *path, bool rcu_walk) | |
427 | { | |
428 | struct dentry *dentry = path->dentry; | |
429 | struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb); | |
430 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
431 | int status; | |
432 | ||
433 | pr_debug("dentry=%p %pd\n", dentry, dentry); | |
434 | ||
435 | /* The daemon never waits. */ | |
436 | if (autofs4_oz_mode(sbi)) { | |
437 | if (!path_is_mountpoint(path)) | |
438 | return -EISDIR; | |
439 | return 0; | |
440 | } | |
441 | ||
442 | /* Wait for pending expires */ | |
443 | if (do_expire_wait(path, rcu_walk) == -ECHILD) | |
444 | return -ECHILD; | |
445 | ||
446 | /* | |
447 | * This dentry may be under construction so wait on mount | |
448 | * completion. | |
449 | */ | |
450 | status = autofs4_mount_wait(path, rcu_walk); | |
451 | if (status) | |
452 | return status; | |
453 | ||
454 | if (rcu_walk) { | |
455 | /* We don't need fs_lock in rcu_walk mode, | |
456 | * just testing 'AUTOFS_INFO_NO_RCU' is enough. | |
457 | * simple_empty() takes a spinlock, so leave it | |
458 | * to last. | |
459 | * We only return -EISDIR when certain this isn't | |
460 | * a mount-trap. | |
461 | */ | |
462 | struct inode *inode; | |
463 | ||
464 | if (ino->flags & AUTOFS_INF_WANT_EXPIRE) | |
465 | return 0; | |
466 | if (path_is_mountpoint(path)) | |
467 | return 0; | |
468 | inode = d_inode_rcu(dentry); | |
469 | if (inode && S_ISLNK(inode->i_mode)) | |
470 | return -EISDIR; | |
471 | if (list_empty(&dentry->d_subdirs)) | |
472 | return 0; | |
473 | if (!simple_empty(dentry)) | |
474 | return -EISDIR; | |
475 | return 0; | |
476 | } | |
477 | ||
478 | spin_lock(&sbi->fs_lock); | |
479 | /* | |
480 | * If the dentry has been selected for expire while we slept | |
481 | * on the lock then it might go away. We'll deal with that in | |
482 | * ->d_automount() and wait on a new mount if the expire | |
483 | * succeeds or return here if it doesn't (since there's no | |
484 | * mount to follow with a rootless multi-mount). | |
485 | */ | |
486 | if (!(ino->flags & AUTOFS_INF_EXPIRING)) { | |
487 | /* | |
488 | * Any needed mounting has been completed and the path | |
489 | * updated so check if this is a rootless multi-mount so | |
490 | * we can avoid needless calls ->d_automount() and avoid | |
491 | * an incorrect ELOOP error return. | |
492 | */ | |
493 | if ((!path_is_mountpoint(path) && !simple_empty(dentry)) || | |
494 | (d_really_is_positive(dentry) && d_is_symlink(dentry))) | |
495 | status = -EISDIR; | |
496 | } | |
497 | spin_unlock(&sbi->fs_lock); | |
498 | ||
499 | return status; | |
500 | } | |
501 | ||
502 | /* Lookups in the root directory */ | |
503 | static struct dentry *autofs4_lookup(struct inode *dir, | |
504 | struct dentry *dentry, unsigned int flags) | |
505 | { | |
506 | struct autofs_sb_info *sbi; | |
507 | struct autofs_info *ino; | |
508 | struct dentry *active; | |
509 | ||
510 | pr_debug("name = %pd\n", dentry); | |
511 | ||
512 | /* File name too long to exist */ | |
513 | if (dentry->d_name.len > NAME_MAX) | |
514 | return ERR_PTR(-ENAMETOOLONG); | |
515 | ||
516 | sbi = autofs4_sbi(dir->i_sb); | |
517 | ||
518 | pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n", | |
519 | current->pid, task_pgrp_nr(current), sbi->catatonic, | |
520 | autofs4_oz_mode(sbi)); | |
521 | ||
522 | active = autofs4_lookup_active(dentry); | |
523 | if (active) | |
524 | return active; | |
525 | else { | |
526 | /* | |
527 | * A dentry that is not within the root can never trigger a | |
528 | * mount operation, unless the directory already exists, so we | |
529 | * can return fail immediately. The daemon however does need | |
530 | * to create directories within the file system. | |
531 | */ | |
532 | if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent)) | |
533 | return ERR_PTR(-ENOENT); | |
534 | ||
535 | /* Mark entries in the root as mount triggers */ | |
536 | if (IS_ROOT(dentry->d_parent) && | |
537 | autofs_type_indirect(sbi->type)) | |
538 | __managed_dentry_set_managed(dentry); | |
539 | ||
540 | ino = autofs4_new_ino(sbi); | |
541 | if (!ino) | |
542 | return ERR_PTR(-ENOMEM); | |
543 | ||
544 | dentry->d_fsdata = ino; | |
545 | ino->dentry = dentry; | |
546 | ||
547 | autofs4_add_active(dentry); | |
548 | } | |
549 | return NULL; | |
550 | } | |
551 | ||
552 | static int autofs4_dir_symlink(struct inode *dir, | |
553 | struct dentry *dentry, | |
554 | const char *symname) | |
555 | { | |
556 | struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb); | |
557 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
558 | struct autofs_info *p_ino; | |
559 | struct inode *inode; | |
560 | size_t size = strlen(symname); | |
561 | char *cp; | |
562 | ||
563 | pr_debug("%s <- %pd\n", symname, dentry); | |
564 | ||
565 | if (!autofs4_oz_mode(sbi)) | |
566 | return -EACCES; | |
567 | ||
568 | BUG_ON(!ino); | |
569 | ||
570 | autofs4_clean_ino(ino); | |
571 | ||
572 | autofs4_del_active(dentry); | |
573 | ||
574 | cp = kmalloc(size + 1, GFP_KERNEL); | |
575 | if (!cp) | |
576 | return -ENOMEM; | |
577 | ||
578 | strcpy(cp, symname); | |
579 | ||
580 | inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555); | |
581 | if (!inode) { | |
582 | kfree(cp); | |
583 | return -ENOMEM; | |
584 | } | |
585 | inode->i_private = cp; | |
586 | inode->i_size = size; | |
587 | d_add(dentry, inode); | |
588 | ||
589 | dget(dentry); | |
590 | atomic_inc(&ino->count); | |
591 | p_ino = autofs4_dentry_ino(dentry->d_parent); | |
592 | if (p_ino && !IS_ROOT(dentry)) | |
593 | atomic_inc(&p_ino->count); | |
594 | ||
595 | dir->i_mtime = current_time(dir); | |
596 | ||
597 | return 0; | |
598 | } | |
599 | ||
600 | /* | |
601 | * NOTE! | |
602 | * | |
603 | * Normal filesystems would do a "d_delete()" to tell the VFS dcache | |
604 | * that the file no longer exists. However, doing that means that the | |
605 | * VFS layer can turn the dentry into a negative dentry. We don't want | |
606 | * this, because the unlink is probably the result of an expire. | |
607 | * We simply d_drop it and add it to a expiring list in the super block, | |
608 | * which allows the dentry lookup to check for an incomplete expire. | |
609 | * | |
610 | * If a process is blocked on the dentry waiting for the expire to finish, | |
611 | * it will invalidate the dentry and try to mount with a new one. | |
612 | * | |
613 | * Also see autofs4_dir_rmdir().. | |
614 | */ | |
615 | static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry) | |
616 | { | |
617 | struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb); | |
618 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
619 | struct autofs_info *p_ino; | |
620 | ||
621 | /* This allows root to remove symlinks */ | |
622 | if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) | |
623 | return -EPERM; | |
624 | ||
625 | if (atomic_dec_and_test(&ino->count)) { | |
626 | p_ino = autofs4_dentry_ino(dentry->d_parent); | |
627 | if (p_ino && !IS_ROOT(dentry)) | |
628 | atomic_dec(&p_ino->count); | |
629 | } | |
630 | dput(ino->dentry); | |
631 | ||
632 | d_inode(dentry)->i_size = 0; | |
633 | clear_nlink(d_inode(dentry)); | |
634 | ||
635 | dir->i_mtime = current_time(dir); | |
636 | ||
637 | spin_lock(&sbi->lookup_lock); | |
638 | __autofs4_add_expiring(dentry); | |
639 | d_drop(dentry); | |
640 | spin_unlock(&sbi->lookup_lock); | |
641 | ||
642 | return 0; | |
643 | } | |
644 | ||
645 | /* | |
646 | * Version 4 of autofs provides a pseudo direct mount implementation | |
647 | * that relies on directories at the leaves of a directory tree under | |
648 | * an indirect mount to trigger mounts. To allow for this we need to | |
649 | * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves | |
650 | * of the directory tree. There is no need to clear the automount flag | |
651 | * following a mount or restore it after an expire because these mounts | |
652 | * are always covered. However, it is necessary to ensure that these | |
653 | * flags are clear on non-empty directories to avoid unnecessary calls | |
654 | * during path walks. | |
655 | */ | |
656 | static void autofs_set_leaf_automount_flags(struct dentry *dentry) | |
657 | { | |
658 | struct dentry *parent; | |
659 | ||
660 | /* root and dentrys in the root are already handled */ | |
661 | if (IS_ROOT(dentry->d_parent)) | |
662 | return; | |
663 | ||
664 | managed_dentry_set_managed(dentry); | |
665 | ||
666 | parent = dentry->d_parent; | |
667 | /* only consider parents below dentrys in the root */ | |
668 | if (IS_ROOT(parent->d_parent)) | |
669 | return; | |
670 | managed_dentry_clear_managed(parent); | |
671 | } | |
672 | ||
673 | static void autofs_clear_leaf_automount_flags(struct dentry *dentry) | |
674 | { | |
675 | struct list_head *d_child; | |
676 | struct dentry *parent; | |
677 | ||
678 | /* flags for dentrys in the root are handled elsewhere */ | |
679 | if (IS_ROOT(dentry->d_parent)) | |
680 | return; | |
681 | ||
682 | managed_dentry_clear_managed(dentry); | |
683 | ||
684 | parent = dentry->d_parent; | |
685 | /* only consider parents below dentrys in the root */ | |
686 | if (IS_ROOT(parent->d_parent)) | |
687 | return; | |
688 | d_child = &dentry->d_child; | |
689 | /* Set parent managed if it's becoming empty */ | |
690 | if (d_child->next == &parent->d_subdirs && | |
691 | d_child->prev == &parent->d_subdirs) | |
692 | managed_dentry_set_managed(parent); | |
693 | } | |
694 | ||
695 | static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry) | |
696 | { | |
697 | struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb); | |
698 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
699 | struct autofs_info *p_ino; | |
700 | ||
701 | pr_debug("dentry %p, removing %pd\n", dentry, dentry); | |
702 | ||
703 | if (!autofs4_oz_mode(sbi)) | |
704 | return -EACCES; | |
705 | ||
706 | spin_lock(&sbi->lookup_lock); | |
707 | if (!simple_empty(dentry)) { | |
708 | spin_unlock(&sbi->lookup_lock); | |
709 | return -ENOTEMPTY; | |
710 | } | |
711 | __autofs4_add_expiring(dentry); | |
712 | d_drop(dentry); | |
713 | spin_unlock(&sbi->lookup_lock); | |
714 | ||
715 | if (sbi->version < 5) | |
716 | autofs_clear_leaf_automount_flags(dentry); | |
717 | ||
718 | if (atomic_dec_and_test(&ino->count)) { | |
719 | p_ino = autofs4_dentry_ino(dentry->d_parent); | |
720 | if (p_ino && dentry->d_parent != dentry) | |
721 | atomic_dec(&p_ino->count); | |
722 | } | |
723 | dput(ino->dentry); | |
724 | d_inode(dentry)->i_size = 0; | |
725 | clear_nlink(d_inode(dentry)); | |
726 | ||
727 | if (dir->i_nlink) | |
728 | drop_nlink(dir); | |
729 | ||
730 | return 0; | |
731 | } | |
732 | ||
733 | static int autofs4_dir_mkdir(struct inode *dir, | |
734 | struct dentry *dentry, umode_t mode) | |
735 | { | |
736 | struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb); | |
737 | struct autofs_info *ino = autofs4_dentry_ino(dentry); | |
738 | struct autofs_info *p_ino; | |
739 | struct inode *inode; | |
740 | ||
741 | if (!autofs4_oz_mode(sbi)) | |
742 | return -EACCES; | |
743 | ||
744 | pr_debug("dentry %p, creating %pd\n", dentry, dentry); | |
745 | ||
746 | BUG_ON(!ino); | |
747 | ||
748 | autofs4_clean_ino(ino); | |
749 | ||
750 | autofs4_del_active(dentry); | |
751 | ||
752 | inode = autofs4_get_inode(dir->i_sb, S_IFDIR | mode); | |
753 | if (!inode) | |
754 | return -ENOMEM; | |
755 | d_add(dentry, inode); | |
756 | ||
757 | if (sbi->version < 5) | |
758 | autofs_set_leaf_automount_flags(dentry); | |
759 | ||
760 | dget(dentry); | |
761 | atomic_inc(&ino->count); | |
762 | p_ino = autofs4_dentry_ino(dentry->d_parent); | |
763 | if (p_ino && !IS_ROOT(dentry)) | |
764 | atomic_inc(&p_ino->count); | |
765 | inc_nlink(dir); | |
766 | dir->i_mtime = current_time(dir); | |
767 | ||
768 | return 0; | |
769 | } | |
770 | ||
771 | /* Get/set timeout ioctl() operation */ | |
772 | #ifdef CONFIG_COMPAT | |
773 | static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi, | |
774 | compat_ulong_t __user *p) | |
775 | { | |
776 | unsigned long ntimeout; | |
777 | int rv; | |
778 | ||
779 | rv = get_user(ntimeout, p); | |
780 | if (rv) | |
781 | goto error; | |
782 | ||
783 | rv = put_user(sbi->exp_timeout/HZ, p); | |
784 | if (rv) | |
785 | goto error; | |
786 | ||
787 | if (ntimeout > UINT_MAX/HZ) | |
788 | sbi->exp_timeout = 0; | |
789 | else | |
790 | sbi->exp_timeout = ntimeout * HZ; | |
791 | ||
792 | return 0; | |
793 | error: | |
794 | return rv; | |
795 | } | |
796 | #endif | |
797 | ||
798 | static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi, | |
799 | unsigned long __user *p) | |
800 | { | |
801 | unsigned long ntimeout; | |
802 | int rv; | |
803 | ||
804 | rv = get_user(ntimeout, p); | |
805 | if (rv) | |
806 | goto error; | |
807 | ||
808 | rv = put_user(sbi->exp_timeout/HZ, p); | |
809 | if (rv) | |
810 | goto error; | |
811 | ||
812 | if (ntimeout > ULONG_MAX/HZ) | |
813 | sbi->exp_timeout = 0; | |
814 | else | |
815 | sbi->exp_timeout = ntimeout * HZ; | |
816 | ||
817 | return 0; | |
818 | error: | |
819 | return rv; | |
820 | } | |
821 | ||
822 | /* Return protocol version */ | |
823 | static inline int autofs4_get_protover(struct autofs_sb_info *sbi, | |
824 | int __user *p) | |
825 | { | |
826 | return put_user(sbi->version, p); | |
827 | } | |
828 | ||
829 | /* Return protocol sub version */ | |
830 | static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, | |
831 | int __user *p) | |
832 | { | |
833 | return put_user(sbi->sub_version, p); | |
834 | } | |
835 | ||
836 | /* | |
837 | * Tells the daemon whether it can umount the autofs mount. | |
838 | */ | |
839 | static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p) | |
840 | { | |
841 | int status = 0; | |
842 | ||
843 | if (may_umount(mnt)) | |
844 | status = 1; | |
845 | ||
846 | pr_debug("may umount %d\n", status); | |
847 | ||
848 | status = put_user(status, p); | |
849 | ||
850 | return status; | |
851 | } | |
852 | ||
853 | /* Identify autofs4_dentries - this is so we can tell if there's | |
854 | * an extra dentry refcount or not. We only hold a refcount on the | |
855 | * dentry if its non-negative (ie, d_inode != NULL) | |
856 | */ | |
857 | int is_autofs4_dentry(struct dentry *dentry) | |
858 | { | |
859 | return dentry && d_really_is_positive(dentry) && | |
860 | dentry->d_op == &autofs4_dentry_operations && | |
861 | dentry->d_fsdata != NULL; | |
862 | } | |
863 | ||
864 | /* | |
865 | * ioctl()'s on the root directory is the chief method for the daemon to | |
866 | * generate kernel reactions | |
867 | */ | |
868 | static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp, | |
869 | unsigned int cmd, unsigned long arg) | |
870 | { | |
871 | struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb); | |
872 | void __user *p = (void __user *)arg; | |
873 | ||
874 | pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n", | |
875 | cmd, arg, sbi, task_pgrp_nr(current)); | |
876 | ||
877 | if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) || | |
878 | _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT) | |
879 | return -ENOTTY; | |
880 | ||
881 | if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN)) | |
882 | return -EPERM; | |
883 | ||
884 | switch (cmd) { | |
885 | case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */ | |
886 | return autofs4_wait_release(sbi, (autofs_wqt_t) arg, 0); | |
887 | case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */ | |
888 | return autofs4_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT); | |
889 | case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */ | |
890 | autofs4_catatonic_mode(sbi); | |
891 | return 0; | |
892 | case AUTOFS_IOC_PROTOVER: /* Get protocol version */ | |
893 | return autofs4_get_protover(sbi, p); | |
894 | case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */ | |
895 | return autofs4_get_protosubver(sbi, p); | |
896 | case AUTOFS_IOC_SETTIMEOUT: | |
897 | return autofs4_get_set_timeout(sbi, p); | |
898 | #ifdef CONFIG_COMPAT | |
899 | case AUTOFS_IOC_SETTIMEOUT32: | |
900 | return autofs4_compat_get_set_timeout(sbi, p); | |
901 | #endif | |
902 | ||
903 | case AUTOFS_IOC_ASKUMOUNT: | |
904 | return autofs4_ask_umount(filp->f_path.mnt, p); | |
905 | ||
906 | /* return a single thing to expire */ | |
907 | case AUTOFS_IOC_EXPIRE: | |
908 | return autofs4_expire_run(inode->i_sb, | |
909 | 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, | |
913 | filp->f_path.mnt, sbi, p); | |
914 | ||
915 | default: | |
916 | return -EINVAL; | |
917 | } | |
918 | } | |
919 | ||
920 | static long autofs4_root_ioctl(struct file *filp, | |
921 | unsigned int cmd, unsigned long arg) | |
922 | { | |
923 | struct inode *inode = file_inode(filp); | |
924 | ||
925 | return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg); | |
926 | } | |
927 | ||
928 | #ifdef CONFIG_COMPAT | |
929 | static long autofs4_root_compat_ioctl(struct file *filp, | |
930 | unsigned int cmd, unsigned long arg) | |
931 | { | |
932 | struct inode *inode = file_inode(filp); | |
933 | int ret; | |
934 | ||
935 | if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL) | |
936 | ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg); | |
937 | else | |
938 | ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, | |
939 | (unsigned long) compat_ptr(arg)); | |
940 | ||
941 | return ret; | |
942 | } | |
943 | #endif |