Version:  2.0.40 2.2.26 2.4.37 3.2 3.3 3.4 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

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(wait);
231 
232         start = buf;
233         group = file->private_data;
234 
235         while (1) {
236                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
237 
238                 mutex_lock(&group->notification_mutex);
239                 kevent = get_one_event(group, count);
240                 mutex_unlock(&group->notification_mutex);
241 
242                 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
243 
244                 if (kevent) {
245                         ret = PTR_ERR(kevent);
246                         if (IS_ERR(kevent))
247                                 break;
248                         ret = copy_event_to_user(group, kevent, buf);
249                         fsnotify_destroy_event(group, kevent);
250                         if (ret < 0)
251                                 break;
252                         buf += ret;
253                         count -= ret;
254                         continue;
255                 }
256 
257                 ret = -EAGAIN;
258                 if (file->f_flags & O_NONBLOCK)
259                         break;
260                 ret = -ERESTARTSYS;
261                 if (signal_pending(current))
262                         break;
263 
264                 if (start != buf)
265                         break;
266 
267                 schedule();
268         }
269 
270         finish_wait(&group->notification_waitq, &wait);
271         if (start != buf && ret != -EFAULT)
272                 ret = buf - start;
273         return ret;
274 }
275 
276 static int inotify_release(struct inode *ignored, struct file *file)
277 {
278         struct fsnotify_group *group = file->private_data;
279 
280         pr_debug("%s: group=%p\n", __func__, group);
281 
282         /* free this group, matching get was inotify_init->fsnotify_obtain_group */
283         fsnotify_destroy_group(group);
284 
285         return 0;
286 }
287 
288 static long inotify_ioctl(struct file *file, unsigned int cmd,
289                           unsigned long arg)
290 {
291         struct fsnotify_group *group;
292         struct fsnotify_event *fsn_event;
293         void __user *p;
294         int ret = -ENOTTY;
295         size_t send_len = 0;
296 
297         group = file->private_data;
298         p = (void __user *) arg;
299 
300         pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
301 
302         switch (cmd) {
303         case FIONREAD:
304                 mutex_lock(&group->notification_mutex);
305                 list_for_each_entry(fsn_event, &group->notification_list,
306                                     list) {
307                         send_len += sizeof(struct inotify_event);
308                         send_len += round_event_name_len(fsn_event);
309                 }
310                 mutex_unlock(&group->notification_mutex);
311                 ret = put_user(send_len, (int __user *) p);
312                 break;
313         }
314 
315         return ret;
316 }
317 
318 static const struct file_operations inotify_fops = {
319         .show_fdinfo    = inotify_show_fdinfo,
320         .poll           = inotify_poll,
321         .read           = inotify_read,
322         .fasync         = fsnotify_fasync,
323         .release        = inotify_release,
324         .unlocked_ioctl = inotify_ioctl,
325         .compat_ioctl   = inotify_ioctl,
326         .llseek         = noop_llseek,
327 };
328 
329 
330 /*
331  * find_inode - resolve a user-given path to a specific inode
332  */
333 static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags)
334 {
335         int error;
336 
337         error = user_path_at(AT_FDCWD, dirname, flags, path);
338         if (error)
339                 return error;
340         /* you can only watch an inode if you have read permissions on it */
341         error = inode_permission(path->dentry->d_inode, MAY_READ);
342         if (error)
343                 path_put(path);
344         return error;
345 }
346 
347 static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
348                               struct inotify_inode_mark *i_mark)
349 {
350         int ret;
351 
352         idr_preload(GFP_KERNEL);
353         spin_lock(idr_lock);
354 
355         ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
356         if (ret >= 0) {
357                 /* we added the mark to the idr, take a reference */
358                 i_mark->wd = ret;
359                 fsnotify_get_mark(&i_mark->fsn_mark);
360         }
361 
362         spin_unlock(idr_lock);
363         idr_preload_end();
364         return ret < 0 ? ret : 0;
365 }
366 
367 static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group,
368                                                                 int wd)
369 {
370         struct idr *idr = &group->inotify_data.idr;
371         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
372         struct inotify_inode_mark *i_mark;
373 
374         assert_spin_locked(idr_lock);
375 
376         i_mark = idr_find(idr, wd);
377         if (i_mark) {
378                 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
379 
380                 fsnotify_get_mark(fsn_mark);
381                 /* One ref for being in the idr, one ref we just took */
382                 BUG_ON(atomic_read(&fsn_mark->refcnt) < 2);
383         }
384 
385         return i_mark;
386 }
387 
388 static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
389                                                          int wd)
390 {
391         struct inotify_inode_mark *i_mark;
392         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
393 
394         spin_lock(idr_lock);
395         i_mark = inotify_idr_find_locked(group, wd);
396         spin_unlock(idr_lock);
397 
398         return i_mark;
399 }
400 
401 static void do_inotify_remove_from_idr(struct fsnotify_group *group,
402                                        struct inotify_inode_mark *i_mark)
403 {
404         struct idr *idr = &group->inotify_data.idr;
405         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
406         int wd = i_mark->wd;
407 
408         assert_spin_locked(idr_lock);
409 
410         idr_remove(idr, wd);
411 
412         /* removed from the idr, drop that ref */
413         fsnotify_put_mark(&i_mark->fsn_mark);
414 }
415 
416 /*
417  * Remove the mark from the idr (if present) and drop the reference
418  * on the mark because it was in the idr.
419  */
420 static void inotify_remove_from_idr(struct fsnotify_group *group,
421                                     struct inotify_inode_mark *i_mark)
422 {
423         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
424         struct inotify_inode_mark *found_i_mark = NULL;
425         int wd;
426 
427         spin_lock(idr_lock);
428         wd = i_mark->wd;
429 
430         /*
431          * does this i_mark think it is in the idr?  we shouldn't get called
432          * if it wasn't....
433          */
434         if (wd == -1) {
435                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
436                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
437                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
438                 goto out;
439         }
440 
441         /* Lets look in the idr to see if we find it */
442         found_i_mark = inotify_idr_find_locked(group, wd);
443         if (unlikely(!found_i_mark)) {
444                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
445                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
446                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
447                 goto out;
448         }
449 
450         /*
451          * We found an mark in the idr at the right wd, but it's
452          * not the mark we were told to remove.  eparis seriously
453          * fucked up somewhere.
454          */
455         if (unlikely(found_i_mark != i_mark)) {
456                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
457                         "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d "
458                         "found_i_mark->group=%p found_i_mark->inode=%p\n",
459                         __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group,
460                         i_mark->fsn_mark.i.inode, found_i_mark, found_i_mark->wd,
461                         found_i_mark->fsn_mark.group,
462                         found_i_mark->fsn_mark.i.inode);
463                 goto out;
464         }
465 
466         /*
467          * One ref for being in the idr
468          * one ref held by the caller trying to kill us
469          * one ref grabbed by inotify_idr_find
470          */
471         if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) {
472                 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
473                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
474                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
475                 /* we can't really recover with bad ref cnting.. */
476                 BUG();
477         }
478 
479         do_inotify_remove_from_idr(group, i_mark);
480 out:
481         /* match the ref taken by inotify_idr_find_locked() */
482         if (found_i_mark)
483                 fsnotify_put_mark(&found_i_mark->fsn_mark);
484         i_mark->wd = -1;
485         spin_unlock(idr_lock);
486 }
487 
488 /*
489  * Send IN_IGNORED for this wd, remove this wd from the idr.
490  */
491 void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
492                                     struct fsnotify_group *group)
493 {
494         struct inotify_inode_mark *i_mark;
495 
496         /* Queue ignore event for the watch */
497         inotify_handle_event(group, NULL, fsn_mark, NULL, FS_IN_IGNORED,
498                              NULL, FSNOTIFY_EVENT_NONE, NULL, 0);
499 
500         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
501         /* remove this mark from the idr */
502         inotify_remove_from_idr(group, i_mark);
503 
504         atomic_dec(&group->inotify_data.user->inotify_watches);
505 }
506 
507 /* ding dong the mark is dead */
508 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
509 {
510         struct inotify_inode_mark *i_mark;
511 
512         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
513 
514         kmem_cache_free(inotify_inode_mark_cachep, i_mark);
515 }
516 
517 static int inotify_update_existing_watch(struct fsnotify_group *group,
518                                          struct inode *inode,
519                                          u32 arg)
520 {
521         struct fsnotify_mark *fsn_mark;
522         struct inotify_inode_mark *i_mark;
523         __u32 old_mask, new_mask;
524         __u32 mask;
525         int add = (arg & IN_MASK_ADD);
526         int ret;
527 
528         mask = inotify_arg_to_mask(arg);
529 
530         fsn_mark = fsnotify_find_inode_mark(group, inode);
531         if (!fsn_mark)
532                 return -ENOENT;
533 
534         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
535 
536         spin_lock(&fsn_mark->lock);
537 
538         old_mask = fsn_mark->mask;
539         if (add)
540                 fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask));
541         else
542                 fsnotify_set_mark_mask_locked(fsn_mark, mask);
543         new_mask = fsn_mark->mask;
544 
545         spin_unlock(&fsn_mark->lock);
546 
547         if (old_mask != new_mask) {
548                 /* more bits in old than in new? */
549                 int dropped = (old_mask & ~new_mask);
550                 /* more bits in this fsn_mark than the inode's mask? */
551                 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
552 
553                 /* update the inode with this new fsn_mark */
554                 if (dropped || do_inode)
555                         fsnotify_recalc_inode_mask(inode);
556 
557         }
558 
559         /* return the wd */
560         ret = i_mark->wd;
561 
562         /* match the get from fsnotify_find_mark() */
563         fsnotify_put_mark(fsn_mark);
564 
565         return ret;
566 }
567 
568 static int inotify_new_watch(struct fsnotify_group *group,
569                              struct inode *inode,
570                              u32 arg)
571 {
572         struct inotify_inode_mark *tmp_i_mark;
573         __u32 mask;
574         int ret;
575         struct idr *idr = &group->inotify_data.idr;
576         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
577 
578         mask = inotify_arg_to_mask(arg);
579 
580         tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
581         if (unlikely(!tmp_i_mark))
582                 return -ENOMEM;
583 
584         fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
585         tmp_i_mark->fsn_mark.mask = mask;
586         tmp_i_mark->wd = -1;
587 
588         ret = -ENOSPC;
589         if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
590                 goto out_err;
591 
592         ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
593         if (ret)
594                 goto out_err;
595 
596         /* we are on the idr, now get on the inode */
597         ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, group, inode,
598                                        NULL, 0);
599         if (ret) {
600                 /* we failed to get on the inode, get off the idr */
601                 inotify_remove_from_idr(group, tmp_i_mark);
602                 goto out_err;
603         }
604 
605         /* increment the number of watches the user has */
606         atomic_inc(&group->inotify_data.user->inotify_watches);
607 
608         /* return the watch descriptor for this new mark */
609         ret = tmp_i_mark->wd;
610 
611 out_err:
612         /* match the ref from fsnotify_init_mark() */
613         fsnotify_put_mark(&tmp_i_mark->fsn_mark);
614 
615         return ret;
616 }
617 
618 static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
619 {
620         int ret = 0;
621 
622         mutex_lock(&group->mark_mutex);
623         /* try to update and existing watch with the new arg */
624         ret = inotify_update_existing_watch(group, inode, arg);
625         /* no mark present, try to add a new one */
626         if (ret == -ENOENT)
627                 ret = inotify_new_watch(group, inode, arg);
628         mutex_unlock(&group->mark_mutex);
629 
630         return ret;
631 }
632 
633 static struct fsnotify_group *inotify_new_group(unsigned int max_events)
634 {
635         struct fsnotify_group *group;
636         struct inotify_event_info *oevent;
637 
638         group = fsnotify_alloc_group(&inotify_fsnotify_ops);
639         if (IS_ERR(group))
640                 return group;
641 
642         oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
643         if (unlikely(!oevent)) {
644                 fsnotify_destroy_group(group);
645                 return ERR_PTR(-ENOMEM);
646         }
647         group->overflow_event = &oevent->fse;
648         fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW);
649         oevent->wd = -1;
650         oevent->sync_cookie = 0;
651         oevent->name_len = 0;
652 
653         group->max_events = max_events;
654 
655         spin_lock_init(&group->inotify_data.idr_lock);
656         idr_init(&group->inotify_data.idr);
657         group->inotify_data.user = get_current_user();
658 
659         if (atomic_inc_return(&group->inotify_data.user->inotify_devs) >
660             inotify_max_user_instances) {
661                 fsnotify_destroy_group(group);
662                 return ERR_PTR(-EMFILE);
663         }
664 
665         return group;
666 }
667 
668 
669 /* inotify syscalls */
670 SYSCALL_DEFINE1(inotify_init1, int, flags)
671 {
672         struct fsnotify_group *group;
673         int ret;
674 
675         /* Check the IN_* constants for consistency.  */
676         BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
677         BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
678 
679         if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
680                 return -EINVAL;
681 
682         /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
683         group = inotify_new_group(inotify_max_queued_events);
684         if (IS_ERR(group))
685                 return PTR_ERR(group);
686 
687         ret = anon_inode_getfd("inotify", &inotify_fops, group,
688                                   O_RDONLY | flags);
689         if (ret < 0)
690                 fsnotify_destroy_group(group);
691 
692         return ret;
693 }
694 
695 SYSCALL_DEFINE0(inotify_init)
696 {
697         return sys_inotify_init1(0);
698 }
699 
700 SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
701                 u32, mask)
702 {
703         struct fsnotify_group *group;
704         struct inode *inode;
705         struct path path;
706         struct fd f;
707         int ret;
708         unsigned flags = 0;
709 
710         /* don't allow invalid bits: we don't want flags set */
711         if (unlikely(!(mask & ALL_INOTIFY_BITS)))
712                 return -EINVAL;
713 
714         f = fdget(fd);
715         if (unlikely(!f.file))
716                 return -EBADF;
717 
718         /* verify that this is indeed an inotify instance */
719         if (unlikely(f.file->f_op != &inotify_fops)) {
720                 ret = -EINVAL;
721                 goto fput_and_out;
722         }
723 
724         if (!(mask & IN_DONT_FOLLOW))
725                 flags |= LOOKUP_FOLLOW;
726         if (mask & IN_ONLYDIR)
727                 flags |= LOOKUP_DIRECTORY;
728 
729         ret = inotify_find_inode(pathname, &path, flags);
730         if (ret)
731                 goto fput_and_out;
732 
733         /* inode held in place by reference to path; group by fget on fd */
734         inode = path.dentry->d_inode;
735         group = f.file->private_data;
736 
737         /* create/update an inode mark */
738         ret = inotify_update_watch(group, inode, mask);
739         path_put(&path);
740 fput_and_out:
741         fdput(f);
742         return ret;
743 }
744 
745 SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
746 {
747         struct fsnotify_group *group;
748         struct inotify_inode_mark *i_mark;
749         struct fd f;
750         int ret = 0;
751 
752         f = fdget(fd);
753         if (unlikely(!f.file))
754                 return -EBADF;
755 
756         /* verify that this is indeed an inotify instance */
757         ret = -EINVAL;
758         if (unlikely(f.file->f_op != &inotify_fops))
759                 goto out;
760 
761         group = f.file->private_data;
762 
763         ret = -EINVAL;
764         i_mark = inotify_idr_find(group, wd);
765         if (unlikely(!i_mark))
766                 goto out;
767 
768         ret = 0;
769 
770         fsnotify_destroy_mark(&i_mark->fsn_mark, group);
771 
772         /* match ref taken by inotify_idr_find */
773         fsnotify_put_mark(&i_mark->fsn_mark);
774 
775 out:
776         fdput(f);
777         return ret;
778 }
779 
780 /*
781  * inotify_user_setup - Our initialization function.  Note that we cannot return
782  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
783  * must result in panic().
784  */
785 static int __init inotify_user_setup(void)
786 {
787         BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
788         BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
789         BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
790         BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
791         BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
792         BUILD_BUG_ON(IN_OPEN != FS_OPEN);
793         BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
794         BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
795         BUILD_BUG_ON(IN_CREATE != FS_CREATE);
796         BUILD_BUG_ON(IN_DELETE != FS_DELETE);
797         BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
798         BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
799         BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
800         BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
801         BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
802         BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
803         BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
804         BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
805 
806         BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
807 
808         inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
809 
810         inotify_max_queued_events = 16384;
811         inotify_max_user_instances = 128;
812         inotify_max_user_watches = 8192;
813 
814         return 0;
815 }
816 module_init(inotify_user_setup);
817 

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