Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/fs/notify/inotify/inotify_user.c

  1 /*
  2  * fs/inotify_user.c - inotify support for userspace
  3  *
  4  * Authors:
  5  *      John McCutchan  <ttb@tentacle.dhs.org>
  6  *      Robert Love     <rml@novell.com>
  7  *
  8  * Copyright (C) 2005 John McCutchan
  9  * Copyright 2006 Hewlett-Packard Development Company, L.P.
 10  *
 11  * Copyright (C) 2009 Eric Paris <Red Hat Inc>
 12  * inotify was largely rewriten to make use of the fsnotify infrastructure
 13  *
 14  * This program is free software; you can redistribute it and/or modify it
 15  * under the terms of the GNU General Public License as published by the
 16  * Free Software Foundation; either version 2, or (at your option) any
 17  * later version.
 18  *
 19  * This program is distributed in the hope that it will be useful, but
 20  * WITHOUT ANY WARRANTY; without even the implied warranty of
 21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 22  * General Public License for more details.
 23  */
 24 
 25 #include <linux/file.h>
 26 #include <linux/fs.h> /* struct inode */
 27 #include <linux/fsnotify_backend.h>
 28 #include <linux/idr.h>
 29 #include <linux/init.h> /* module_init */
 30 #include <linux/inotify.h>
 31 #include <linux/kernel.h> /* roundup() */
 32 #include <linux/namei.h> /* LOOKUP_FOLLOW */
 33 #include <linux/sched.h> /* struct user */
 34 #include <linux/slab.h> /* struct kmem_cache */
 35 #include <linux/syscalls.h>
 36 #include <linux/types.h>
 37 #include <linux/anon_inodes.h>
 38 #include <linux/uaccess.h>
 39 #include <linux/poll.h>
 40 #include <linux/wait.h>
 41 
 42 #include "inotify.h"
 43 #include "../fdinfo.h"
 44 
 45 #include <asm/ioctls.h>
 46 
 47 /* these are configurable via /proc/sys/fs/inotify/ */
 48 static int inotify_max_user_instances __read_mostly;
 49 static int inotify_max_queued_events __read_mostly;
 50 static int inotify_max_user_watches __read_mostly;
 51 
 52 static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
 53 
 54 #ifdef CONFIG_SYSCTL
 55 
 56 #include <linux/sysctl.h>
 57 
 58 static int zero;
 59 
 60 struct ctl_table inotify_table[] = {
 61         {
 62                 .procname       = "max_user_instances",
 63                 .data           = &inotify_max_user_instances,
 64                 .maxlen         = sizeof(int),
 65                 .mode           = 0644,
 66                 .proc_handler   = proc_dointvec_minmax,
 67                 .extra1         = &zero,
 68         },
 69         {
 70                 .procname       = "max_user_watches",
 71                 .data           = &inotify_max_user_watches,
 72                 .maxlen         = sizeof(int),
 73                 .mode           = 0644,
 74                 .proc_handler   = proc_dointvec_minmax,
 75                 .extra1         = &zero,
 76         },
 77         {
 78                 .procname       = "max_queued_events",
 79                 .data           = &inotify_max_queued_events,
 80                 .maxlen         = sizeof(int),
 81                 .mode           = 0644,
 82                 .proc_handler   = proc_dointvec_minmax,
 83                 .extra1         = &zero
 84         },
 85         { }
 86 };
 87 #endif /* CONFIG_SYSCTL */
 88 
 89 static inline __u32 inotify_arg_to_mask(u32 arg)
 90 {
 91         __u32 mask;
 92 
 93         /*
 94          * everything should accept their own ignored, cares about children,
 95          * and should receive events when the inode is unmounted
 96          */
 97         mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);
 98 
 99         /* mask off the flags used to open the fd */
100         mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));
101 
102         return mask;
103 }
104 
105 static inline u32 inotify_mask_to_arg(__u32 mask)
106 {
107         return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED |
108                        IN_Q_OVERFLOW);
109 }
110 
111 /* intofiy userspace file descriptor functions */
112 static unsigned int inotify_poll(struct file *file, poll_table *wait)
113 {
114         struct fsnotify_group *group = file->private_data;
115         int ret = 0;
116 
117         poll_wait(file, &group->notification_waitq, wait);
118         mutex_lock(&group->notification_mutex);
119         if (!fsnotify_notify_queue_is_empty(group))
120                 ret = POLLIN | POLLRDNORM;
121         mutex_unlock(&group->notification_mutex);
122 
123         return ret;
124 }
125 
126 static int round_event_name_len(struct fsnotify_event *fsn_event)
127 {
128         struct inotify_event_info *event;
129 
130         event = INOTIFY_E(fsn_event);
131         if (!event->name_len)
132                 return 0;
133         return roundup(event->name_len + 1, sizeof(struct inotify_event));
134 }
135 
136 /*
137  * Get an inotify_kernel_event if one exists and is small
138  * enough to fit in "count". Return an error pointer if
139  * not large enough.
140  *
141  * Called with the group->notification_mutex held.
142  */
143 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
144                                             size_t count)
145 {
146         size_t event_size = sizeof(struct inotify_event);
147         struct fsnotify_event *event;
148 
149         if (fsnotify_notify_queue_is_empty(group))
150                 return NULL;
151 
152         event = fsnotify_peek_first_event(group);
153 
154         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
155 
156         event_size += round_event_name_len(event);
157         if (event_size > count)
158                 return ERR_PTR(-EINVAL);
159 
160         /* held the notification_mutex the whole time, so this is the
161          * same event we peeked above */
162         fsnotify_remove_first_event(group);
163 
164         return event;
165 }
166 
167 /*
168  * Copy an event to user space, returning how much we copied.
169  *
170  * We already checked that the event size is smaller than the
171  * buffer we had in "get_one_event()" above.
172  */
173 static ssize_t copy_event_to_user(struct fsnotify_group *group,
174                                   struct fsnotify_event *fsn_event,
175                                   char __user *buf)
176 {
177         struct inotify_event inotify_event;
178         struct inotify_event_info *event;
179         size_t event_size = sizeof(struct inotify_event);
180         size_t name_len;
181         size_t pad_name_len;
182 
183         pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
184 
185         event = INOTIFY_E(fsn_event);
186         name_len = event->name_len;
187         /*
188          * round up name length so it is a multiple of event_size
189          * plus an extra byte for the terminating '\0'.
190          */
191         pad_name_len = round_event_name_len(fsn_event);
192         inotify_event.len = pad_name_len;
193         inotify_event.mask = inotify_mask_to_arg(fsn_event->mask);
194         inotify_event.wd = event->wd;
195         inotify_event.cookie = event->sync_cookie;
196 
197         /* send the main event */
198         if (copy_to_user(buf, &inotify_event, event_size))
199                 return -EFAULT;
200 
201         buf += event_size;
202 
203         /*
204          * fsnotify only stores the pathname, so here we have to send the pathname
205          * and then pad that pathname out to a multiple of sizeof(inotify_event)
206          * with zeros.
207          */
208         if (pad_name_len) {
209                 /* copy the path name */
210                 if (copy_to_user(buf, event->name, name_len))
211                         return -EFAULT;
212                 buf += name_len;
213 
214                 /* fill userspace with 0's */
215                 if (clear_user(buf, pad_name_len - name_len))
216                         return -EFAULT;
217                 event_size += pad_name_len;
218         }
219 
220         return event_size;
221 }
222 
223 static ssize_t inotify_read(struct file *file, char __user *buf,
224                             size_t count, loff_t *pos)
225 {
226         struct fsnotify_group *group;
227         struct fsnotify_event *kevent;
228         char __user *start;
229         int ret;
230         DEFINE_WAIT_FUNC(wait, woken_wake_function);
231 
232         start = buf;
233         group = file->private_data;
234 
235         add_wait_queue(&group->notification_waitq, &wait);
236         while (1) {
237                 mutex_lock(&group->notification_mutex);
238                 kevent = get_one_event(group, count);
239                 mutex_unlock(&group->notification_mutex);
240 
241                 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
242 
243                 if (kevent) {
244                         ret = PTR_ERR(kevent);
245                         if (IS_ERR(kevent))
246                                 break;
247                         ret = copy_event_to_user(group, kevent, buf);
248                         fsnotify_destroy_event(group, kevent);
249                         if (ret < 0)
250                                 break;
251                         buf += ret;
252                         count -= ret;
253                         continue;
254                 }
255 
256                 ret = -EAGAIN;
257                 if (file->f_flags & O_NONBLOCK)
258                         break;
259                 ret = -ERESTARTSYS;
260                 if (signal_pending(current))
261                         break;
262 
263                 if (start != buf)
264                         break;
265 
266                 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
267         }
268         remove_wait_queue(&group->notification_waitq, &wait);
269 
270         if (start != buf && ret != -EFAULT)
271                 ret = buf - start;
272         return ret;
273 }
274 
275 static int inotify_release(struct inode *ignored, struct file *file)
276 {
277         struct fsnotify_group *group = file->private_data;
278 
279         pr_debug("%s: group=%p\n", __func__, group);
280 
281         /* free this group, matching get was inotify_init->fsnotify_obtain_group */
282         fsnotify_destroy_group(group);
283 
284         return 0;
285 }
286 
287 static long inotify_ioctl(struct file *file, unsigned int cmd,
288                           unsigned long arg)
289 {
290         struct fsnotify_group *group;
291         struct fsnotify_event *fsn_event;
292         void __user *p;
293         int ret = -ENOTTY;
294         size_t send_len = 0;
295 
296         group = file->private_data;
297         p = (void __user *) arg;
298 
299         pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
300 
301         switch (cmd) {
302         case FIONREAD:
303                 mutex_lock(&group->notification_mutex);
304                 list_for_each_entry(fsn_event, &group->notification_list,
305                                     list) {
306                         send_len += sizeof(struct inotify_event);
307                         send_len += round_event_name_len(fsn_event);
308                 }
309                 mutex_unlock(&group->notification_mutex);
310                 ret = put_user(send_len, (int __user *) p);
311                 break;
312         }
313 
314         return ret;
315 }
316 
317 static const struct file_operations inotify_fops = {
318         .show_fdinfo    = inotify_show_fdinfo,
319         .poll           = inotify_poll,
320         .read           = inotify_read,
321         .fasync         = fsnotify_fasync,
322         .release        = inotify_release,
323         .unlocked_ioctl = inotify_ioctl,
324         .compat_ioctl   = inotify_ioctl,
325         .llseek         = noop_llseek,
326 };
327 
328 
329 /*
330  * find_inode - resolve a user-given path to a specific inode
331  */
332 static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags)
333 {
334         int error;
335 
336         error = user_path_at(AT_FDCWD, dirname, flags, path);
337         if (error)
338                 return error;
339         /* you can only watch an inode if you have read permissions on it */
340         error = inode_permission(path->dentry->d_inode, MAY_READ);
341         if (error)
342                 path_put(path);
343         return error;
344 }
345 
346 static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
347                               struct inotify_inode_mark *i_mark)
348 {
349         int ret;
350 
351         idr_preload(GFP_KERNEL);
352         spin_lock(idr_lock);
353 
354         ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
355         if (ret >= 0) {
356                 /* we added the mark to the idr, take a reference */
357                 i_mark->wd = ret;
358                 fsnotify_get_mark(&i_mark->fsn_mark);
359         }
360 
361         spin_unlock(idr_lock);
362         idr_preload_end();
363         return ret < 0 ? ret : 0;
364 }
365 
366 static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group,
367                                                                 int wd)
368 {
369         struct idr *idr = &group->inotify_data.idr;
370         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
371         struct inotify_inode_mark *i_mark;
372 
373         assert_spin_locked(idr_lock);
374 
375         i_mark = idr_find(idr, wd);
376         if (i_mark) {
377                 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
378 
379                 fsnotify_get_mark(fsn_mark);
380                 /* One ref for being in the idr, one ref we just took */
381                 BUG_ON(atomic_read(&fsn_mark->refcnt) < 2);
382         }
383 
384         return i_mark;
385 }
386 
387 static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
388                                                          int wd)
389 {
390         struct inotify_inode_mark *i_mark;
391         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
392 
393         spin_lock(idr_lock);
394         i_mark = inotify_idr_find_locked(group, wd);
395         spin_unlock(idr_lock);
396 
397         return i_mark;
398 }
399 
400 static void do_inotify_remove_from_idr(struct fsnotify_group *group,
401                                        struct inotify_inode_mark *i_mark)
402 {
403         struct idr *idr = &group->inotify_data.idr;
404         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
405         int wd = i_mark->wd;
406 
407         assert_spin_locked(idr_lock);
408 
409         idr_remove(idr, wd);
410 
411         /* removed from the idr, drop that ref */
412         fsnotify_put_mark(&i_mark->fsn_mark);
413 }
414 
415 /*
416  * Remove the mark from the idr (if present) and drop the reference
417  * on the mark because it was in the idr.
418  */
419 static void inotify_remove_from_idr(struct fsnotify_group *group,
420                                     struct inotify_inode_mark *i_mark)
421 {
422         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
423         struct inotify_inode_mark *found_i_mark = NULL;
424         int wd;
425 
426         spin_lock(idr_lock);
427         wd = i_mark->wd;
428 
429         /*
430          * does this i_mark think it is in the idr?  we shouldn't get called
431          * if it wasn't....
432          */
433         if (wd == -1) {
434                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
435                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
436                         i_mark->fsn_mark.group, i_mark->fsn_mark.inode);
437                 goto out;
438         }
439 
440         /* Lets look in the idr to see if we find it */
441         found_i_mark = inotify_idr_find_locked(group, wd);
442         if (unlikely(!found_i_mark)) {
443                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
444                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
445                         i_mark->fsn_mark.group, i_mark->fsn_mark.inode);
446                 goto out;
447         }
448 
449         /*
450          * We found an mark in the idr at the right wd, but it's
451          * not the mark we were told to remove.  eparis seriously
452          * fucked up somewhere.
453          */
454         if (unlikely(found_i_mark != i_mark)) {
455                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
456                         "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d "
457                         "found_i_mark->group=%p found_i_mark->inode=%p\n",
458                         __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group,
459                         i_mark->fsn_mark.inode, found_i_mark, found_i_mark->wd,
460                         found_i_mark->fsn_mark.group,
461                         found_i_mark->fsn_mark.inode);
462                 goto out;
463         }
464 
465         /*
466          * One ref for being in the idr
467          * one ref held by the caller trying to kill us
468          * one ref grabbed by inotify_idr_find
469          */
470         if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) {
471                 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
472                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
473                         i_mark->fsn_mark.group, i_mark->fsn_mark.inode);
474                 /* we can't really recover with bad ref cnting.. */
475                 BUG();
476         }
477 
478         do_inotify_remove_from_idr(group, i_mark);
479 out:
480         /* match the ref taken by inotify_idr_find_locked() */
481         if (found_i_mark)
482                 fsnotify_put_mark(&found_i_mark->fsn_mark);
483         i_mark->wd = -1;
484         spin_unlock(idr_lock);
485 }
486 
487 /*
488  * Send IN_IGNORED for this wd, remove this wd from the idr.
489  */
490 void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
491                                     struct fsnotify_group *group)
492 {
493         struct inotify_inode_mark *i_mark;
494 
495         /* Queue ignore event for the watch */
496         inotify_handle_event(group, NULL, fsn_mark, NULL, FS_IN_IGNORED,
497                              NULL, FSNOTIFY_EVENT_NONE, NULL, 0);
498 
499         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
500         /* remove this mark from the idr */
501         inotify_remove_from_idr(group, i_mark);
502 
503         atomic_dec(&group->inotify_data.user->inotify_watches);
504 }
505 
506 /* ding dong the mark is dead */
507 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
508 {
509         struct inotify_inode_mark *i_mark;
510 
511         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
512 
513         kmem_cache_free(inotify_inode_mark_cachep, i_mark);
514 }
515 
516 static int inotify_update_existing_watch(struct fsnotify_group *group,
517                                          struct inode *inode,
518                                          u32 arg)
519 {
520         struct fsnotify_mark *fsn_mark;
521         struct inotify_inode_mark *i_mark;
522         __u32 old_mask, new_mask;
523         __u32 mask;
524         int add = (arg & IN_MASK_ADD);
525         int ret;
526 
527         mask = inotify_arg_to_mask(arg);
528 
529         fsn_mark = fsnotify_find_inode_mark(group, inode);
530         if (!fsn_mark)
531                 return -ENOENT;
532 
533         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
534 
535         spin_lock(&fsn_mark->lock);
536 
537         old_mask = fsn_mark->mask;
538         if (add)
539                 fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask));
540         else
541                 fsnotify_set_mark_mask_locked(fsn_mark, mask);
542         new_mask = fsn_mark->mask;
543 
544         spin_unlock(&fsn_mark->lock);
545 
546         if (old_mask != new_mask) {
547                 /* more bits in old than in new? */
548                 int dropped = (old_mask & ~new_mask);
549                 /* more bits in this fsn_mark than the inode's mask? */
550                 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
551 
552                 /* update the inode with this new fsn_mark */
553                 if (dropped || do_inode)
554                         fsnotify_recalc_inode_mask(inode);
555 
556         }
557 
558         /* return the wd */
559         ret = i_mark->wd;
560 
561         /* match the get from fsnotify_find_mark() */
562         fsnotify_put_mark(fsn_mark);
563 
564         return ret;
565 }
566 
567 static int inotify_new_watch(struct fsnotify_group *group,
568                              struct inode *inode,
569                              u32 arg)
570 {
571         struct inotify_inode_mark *tmp_i_mark;
572         __u32 mask;
573         int ret;
574         struct idr *idr = &group->inotify_data.idr;
575         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
576 
577         mask = inotify_arg_to_mask(arg);
578 
579         tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
580         if (unlikely(!tmp_i_mark))
581                 return -ENOMEM;
582 
583         fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
584         tmp_i_mark->fsn_mark.mask = mask;
585         tmp_i_mark->wd = -1;
586 
587         ret = -ENOSPC;
588         if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
589                 goto out_err;
590 
591         ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
592         if (ret)
593                 goto out_err;
594 
595         /* we are on the idr, now get on the inode */
596         ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, group, inode,
597                                        NULL, 0);
598         if (ret) {
599                 /* we failed to get on the inode, get off the idr */
600                 inotify_remove_from_idr(group, tmp_i_mark);
601                 goto out_err;
602         }
603 
604         /* increment the number of watches the user has */
605         atomic_inc(&group->inotify_data.user->inotify_watches);
606 
607         /* return the watch descriptor for this new mark */
608         ret = tmp_i_mark->wd;
609 
610 out_err:
611         /* match the ref from fsnotify_init_mark() */
612         fsnotify_put_mark(&tmp_i_mark->fsn_mark);
613 
614         return ret;
615 }
616 
617 static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
618 {
619         int ret = 0;
620 
621         mutex_lock(&group->mark_mutex);
622         /* try to update and existing watch with the new arg */
623         ret = inotify_update_existing_watch(group, inode, arg);
624         /* no mark present, try to add a new one */
625         if (ret == -ENOENT)
626                 ret = inotify_new_watch(group, inode, arg);
627         mutex_unlock(&group->mark_mutex);
628 
629         return ret;
630 }
631 
632 static struct fsnotify_group *inotify_new_group(unsigned int max_events)
633 {
634         struct fsnotify_group *group;
635         struct inotify_event_info *oevent;
636 
637         group = fsnotify_alloc_group(&inotify_fsnotify_ops);
638         if (IS_ERR(group))
639                 return group;
640 
641         oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
642         if (unlikely(!oevent)) {
643                 fsnotify_destroy_group(group);
644                 return ERR_PTR(-ENOMEM);
645         }
646         group->overflow_event = &oevent->fse;
647         fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW);
648         oevent->wd = -1;
649         oevent->sync_cookie = 0;
650         oevent->name_len = 0;
651 
652         group->max_events = max_events;
653 
654         spin_lock_init(&group->inotify_data.idr_lock);
655         idr_init(&group->inotify_data.idr);
656         group->inotify_data.user = get_current_user();
657 
658         if (atomic_inc_return(&group->inotify_data.user->inotify_devs) >
659             inotify_max_user_instances) {
660                 fsnotify_destroy_group(group);
661                 return ERR_PTR(-EMFILE);
662         }
663 
664         return group;
665 }
666 
667 
668 /* inotify syscalls */
669 SYSCALL_DEFINE1(inotify_init1, int, flags)
670 {
671         struct fsnotify_group *group;
672         int ret;
673 
674         /* Check the IN_* constants for consistency.  */
675         BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
676         BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
677 
678         if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
679                 return -EINVAL;
680 
681         /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
682         group = inotify_new_group(inotify_max_queued_events);
683         if (IS_ERR(group))
684                 return PTR_ERR(group);
685 
686         ret = anon_inode_getfd("inotify", &inotify_fops, group,
687                                   O_RDONLY | flags);
688         if (ret < 0)
689                 fsnotify_destroy_group(group);
690 
691         return ret;
692 }
693 
694 SYSCALL_DEFINE0(inotify_init)
695 {
696         return sys_inotify_init1(0);
697 }
698 
699 SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
700                 u32, mask)
701 {
702         struct fsnotify_group *group;
703         struct inode *inode;
704         struct path path;
705         struct fd f;
706         int ret;
707         unsigned flags = 0;
708 
709         /* don't allow invalid bits: we don't want flags set */
710         if (unlikely(!(mask & ALL_INOTIFY_BITS)))
711                 return -EINVAL;
712 
713         f = fdget(fd);
714         if (unlikely(!f.file))
715                 return -EBADF;
716 
717         /* verify that this is indeed an inotify instance */
718         if (unlikely(f.file->f_op != &inotify_fops)) {
719                 ret = -EINVAL;
720                 goto fput_and_out;
721         }
722 
723         if (!(mask & IN_DONT_FOLLOW))
724                 flags |= LOOKUP_FOLLOW;
725         if (mask & IN_ONLYDIR)
726                 flags |= LOOKUP_DIRECTORY;
727 
728         ret = inotify_find_inode(pathname, &path, flags);
729         if (ret)
730                 goto fput_and_out;
731 
732         /* inode held in place by reference to path; group by fget on fd */
733         inode = path.dentry->d_inode;
734         group = f.file->private_data;
735 
736         /* create/update an inode mark */
737         ret = inotify_update_watch(group, inode, mask);
738         path_put(&path);
739 fput_and_out:
740         fdput(f);
741         return ret;
742 }
743 
744 SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
745 {
746         struct fsnotify_group *group;
747         struct inotify_inode_mark *i_mark;
748         struct fd f;
749         int ret = 0;
750 
751         f = fdget(fd);
752         if (unlikely(!f.file))
753                 return -EBADF;
754 
755         /* verify that this is indeed an inotify instance */
756         ret = -EINVAL;
757         if (unlikely(f.file->f_op != &inotify_fops))
758                 goto out;
759 
760         group = f.file->private_data;
761 
762         ret = -EINVAL;
763         i_mark = inotify_idr_find(group, wd);
764         if (unlikely(!i_mark))
765                 goto out;
766 
767         ret = 0;
768 
769         fsnotify_destroy_mark(&i_mark->fsn_mark, group);
770 
771         /* match ref taken by inotify_idr_find */
772         fsnotify_put_mark(&i_mark->fsn_mark);
773 
774 out:
775         fdput(f);
776         return ret;
777 }
778 
779 /*
780  * inotify_user_setup - Our initialization function.  Note that we cannot return
781  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
782  * must result in panic().
783  */
784 static int __init inotify_user_setup(void)
785 {
786         BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
787         BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
788         BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
789         BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
790         BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
791         BUILD_BUG_ON(IN_OPEN != FS_OPEN);
792         BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
793         BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
794         BUILD_BUG_ON(IN_CREATE != FS_CREATE);
795         BUILD_BUG_ON(IN_DELETE != FS_DELETE);
796         BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
797         BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
798         BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
799         BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
800         BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
801         BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
802         BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
803         BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
804 
805         BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
806 
807         inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
808 
809         inotify_max_queued_events = 16384;
810         inotify_max_user_instances = 128;
811         inotify_max_user_watches = 8192;
812 
813         return 0;
814 }
815 module_init(inotify_user_setup);
816 

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