~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/notify/inotify/inotify_user.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 
 44 #include <asm/ioctls.h>
 45 
 46 /* these are configurable via /proc/sys/fs/inotify/ */
 47 static int inotify_max_user_instances __read_mostly;
 48 static int inotify_max_queued_events __read_mostly;
 49 static int inotify_max_user_watches __read_mostly;
 50 
 51 static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
 52 struct kmem_cache *event_priv_cachep __read_mostly;
 53 
 54 #ifdef CONFIG_SYSCTL
 55 
 56 #include <linux/sysctl.h>
 57 
 58 static int zero;
 59 
 60 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 /*
127  * Get an inotify_kernel_event if one exists and is small
128  * enough to fit in "count". Return an error pointer if
129  * not large enough.
130  *
131  * Called with the group->notification_mutex held.
132  */
133 static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
134                                             size_t count)
135 {
136         size_t event_size = sizeof(struct inotify_event);
137         struct fsnotify_event *event;
138 
139         if (fsnotify_notify_queue_is_empty(group))
140                 return NULL;
141 
142         event = fsnotify_peek_notify_event(group);
143 
144         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
145 
146         if (event->name_len)
147                 event_size += roundup(event->name_len + 1, event_size);
148 
149         if (event_size > count)
150                 return ERR_PTR(-EINVAL);
151 
152         /* held the notification_mutex the whole time, so this is the
153          * same event we peeked above */
154         fsnotify_remove_notify_event(group);
155 
156         return event;
157 }
158 
159 /*
160  * Copy an event to user space, returning how much we copied.
161  *
162  * We already checked that the event size is smaller than the
163  * buffer we had in "get_one_event()" above.
164  */
165 static ssize_t copy_event_to_user(struct fsnotify_group *group,
166                                   struct fsnotify_event *event,
167                                   char __user *buf)
168 {
169         struct inotify_event inotify_event;
170         struct fsnotify_event_private_data *fsn_priv;
171         struct inotify_event_private_data *priv;
172         size_t event_size = sizeof(struct inotify_event);
173         size_t name_len = 0;
174 
175         pr_debug("%s: group=%p event=%p\n", __func__, group, event);
176 
177         /* we get the inotify watch descriptor from the event private data */
178         spin_lock(&event->lock);
179         fsn_priv = fsnotify_remove_priv_from_event(group, event);
180         spin_unlock(&event->lock);
181 
182         if (!fsn_priv)
183                 inotify_event.wd = -1;
184         else {
185                 priv = container_of(fsn_priv, struct inotify_event_private_data,
186                                     fsnotify_event_priv_data);
187                 inotify_event.wd = priv->wd;
188                 inotify_free_event_priv(fsn_priv);
189         }
190 
191         /*
192          * round up event->name_len so it is a multiple of event_size
193          * plus an extra byte for the terminating '\0'.
194          */
195         if (event->name_len)
196                 name_len = roundup(event->name_len + 1, event_size);
197         inotify_event.len = name_len;
198 
199         inotify_event.mask = inotify_mask_to_arg(event->mask);
200         inotify_event.cookie = event->sync_cookie;
201 
202         /* send the main event */
203         if (copy_to_user(buf, &inotify_event, event_size))
204                 return -EFAULT;
205 
206         buf += event_size;
207 
208         /*
209          * fsnotify only stores the pathname, so here we have to send the pathname
210          * and then pad that pathname out to a multiple of sizeof(inotify_event)
211          * with zeros.  I get my zeros from the nul_inotify_event.
212          */
213         if (name_len) {
214                 unsigned int len_to_zero = name_len - event->name_len;
215                 /* copy the path name */
216                 if (copy_to_user(buf, event->file_name, event->name_len))
217                         return -EFAULT;
218                 buf += event->name_len;
219 
220                 /* fill userspace with 0's */
221                 if (clear_user(buf, len_to_zero))
222                         return -EFAULT;
223                 buf += len_to_zero;
224                 event_size += name_len;
225         }
226 
227         return event_size;
228 }
229 
230 static ssize_t inotify_read(struct file *file, char __user *buf,
231                             size_t count, loff_t *pos)
232 {
233         struct fsnotify_group *group;
234         struct fsnotify_event *kevent;
235         char __user *start;
236         int ret;
237         DEFINE_WAIT(wait);
238 
239         start = buf;
240         group = file->private_data;
241 
242         while (1) {
243                 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
244 
245                 mutex_lock(&group->notification_mutex);
246                 kevent = get_one_event(group, count);
247                 mutex_unlock(&group->notification_mutex);
248 
249                 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
250 
251                 if (kevent) {
252                         ret = PTR_ERR(kevent);
253                         if (IS_ERR(kevent))
254                                 break;
255                         ret = copy_event_to_user(group, kevent, buf);
256                         fsnotify_put_event(kevent);
257                         if (ret < 0)
258                                 break;
259                         buf += ret;
260                         count -= ret;
261                         continue;
262                 }
263 
264                 ret = -EAGAIN;
265                 if (file->f_flags & O_NONBLOCK)
266                         break;
267                 ret = -EINTR;
268                 if (signal_pending(current))
269                         break;
270 
271                 if (start != buf)
272                         break;
273 
274                 schedule();
275         }
276 
277         finish_wait(&group->notification_waitq, &wait);
278         if (start != buf && ret != -EFAULT)
279                 ret = buf - start;
280         return ret;
281 }
282 
283 static int inotify_fasync(int fd, struct file *file, int on)
284 {
285         struct fsnotify_group *group = file->private_data;
286 
287         return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO;
288 }
289 
290 static int inotify_release(struct inode *ignored, struct file *file)
291 {
292         struct fsnotify_group *group = file->private_data;
293 
294         pr_debug("%s: group=%p\n", __func__, group);
295 
296         fsnotify_clear_marks_by_group(group);
297 
298         /* free this group, matching get was inotify_init->fsnotify_obtain_group */
299         fsnotify_put_group(group);
300 
301         return 0;
302 }
303 
304 static long inotify_ioctl(struct file *file, unsigned int cmd,
305                           unsigned long arg)
306 {
307         struct fsnotify_group *group;
308         struct fsnotify_event_holder *holder;
309         struct fsnotify_event *event;
310         void __user *p;
311         int ret = -ENOTTY;
312         size_t send_len = 0;
313 
314         group = file->private_data;
315         p = (void __user *) arg;
316 
317         pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
318 
319         switch (cmd) {
320         case FIONREAD:
321                 mutex_lock(&group->notification_mutex);
322                 list_for_each_entry(holder, &group->notification_list, event_list) {
323                         event = holder->event;
324                         send_len += sizeof(struct inotify_event);
325                         if (event->name_len)
326                                 send_len += roundup(event->name_len + 1,
327                                                 sizeof(struct inotify_event));
328                 }
329                 mutex_unlock(&group->notification_mutex);
330                 ret = put_user(send_len, (int __user *) p);
331                 break;
332         }
333 
334         return ret;
335 }
336 
337 static const struct file_operations inotify_fops = {
338         .poll           = inotify_poll,
339         .read           = inotify_read,
340         .fasync         = inotify_fasync,
341         .release        = inotify_release,
342         .unlocked_ioctl = inotify_ioctl,
343         .compat_ioctl   = inotify_ioctl,
344         .llseek         = noop_llseek,
345 };
346 
347 
348 /*
349  * find_inode - resolve a user-given path to a specific inode
350  */
351 static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags)
352 {
353         int error;
354 
355         error = user_path_at(AT_FDCWD, dirname, flags, path);
356         if (error)
357                 return error;
358         /* you can only watch an inode if you have read permissions on it */
359         error = inode_permission(path->dentry->d_inode, MAY_READ);
360         if (error)
361                 path_put(path);
362         return error;
363 }
364 
365 static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
366                               int *last_wd,
367                               struct inotify_inode_mark *i_mark)
368 {
369         int ret;
370 
371         do {
372                 if (unlikely(!idr_pre_get(idr, GFP_KERNEL)))
373                         return -ENOMEM;
374 
375                 spin_lock(idr_lock);
376                 ret = idr_get_new_above(idr, i_mark, *last_wd + 1,
377                                         &i_mark->wd);
378                 /* we added the mark to the idr, take a reference */
379                 if (!ret) {
380                         *last_wd = i_mark->wd;
381                         fsnotify_get_mark(&i_mark->fsn_mark);
382                 }
383                 spin_unlock(idr_lock);
384         } while (ret == -EAGAIN);
385 
386         return ret;
387 }
388 
389 static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group,
390                                                                 int wd)
391 {
392         struct idr *idr = &group->inotify_data.idr;
393         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
394         struct inotify_inode_mark *i_mark;
395 
396         assert_spin_locked(idr_lock);
397 
398         i_mark = idr_find(idr, wd);
399         if (i_mark) {
400                 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
401 
402                 fsnotify_get_mark(fsn_mark);
403                 /* One ref for being in the idr, one ref we just took */
404                 BUG_ON(atomic_read(&fsn_mark->refcnt) < 2);
405         }
406 
407         return i_mark;
408 }
409 
410 static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
411                                                          int wd)
412 {
413         struct inotify_inode_mark *i_mark;
414         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
415 
416         spin_lock(idr_lock);
417         i_mark = inotify_idr_find_locked(group, wd);
418         spin_unlock(idr_lock);
419 
420         return i_mark;
421 }
422 
423 static void do_inotify_remove_from_idr(struct fsnotify_group *group,
424                                        struct inotify_inode_mark *i_mark)
425 {
426         struct idr *idr = &group->inotify_data.idr;
427         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
428         int wd = i_mark->wd;
429 
430         assert_spin_locked(idr_lock);
431 
432         idr_remove(idr, wd);
433 
434         /* removed from the idr, drop that ref */
435         fsnotify_put_mark(&i_mark->fsn_mark);
436 }
437 
438 /*
439  * Remove the mark from the idr (if present) and drop the reference
440  * on the mark because it was in the idr.
441  */
442 static void inotify_remove_from_idr(struct fsnotify_group *group,
443                                     struct inotify_inode_mark *i_mark)
444 {
445         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
446         struct inotify_inode_mark *found_i_mark = NULL;
447         int wd;
448 
449         spin_lock(idr_lock);
450         wd = i_mark->wd;
451 
452         /*
453          * does this i_mark think it is in the idr?  we shouldn't get called
454          * if it wasn't....
455          */
456         if (wd == -1) {
457                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
458                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
459                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
460                 goto out;
461         }
462 
463         /* Lets look in the idr to see if we find it */
464         found_i_mark = inotify_idr_find_locked(group, wd);
465         if (unlikely(!found_i_mark)) {
466                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
467                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
468                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
469                 goto out;
470         }
471 
472         /*
473          * We found an mark in the idr at the right wd, but it's
474          * not the mark we were told to remove.  eparis seriously
475          * fucked up somewhere.
476          */
477         if (unlikely(found_i_mark != i_mark)) {
478                 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
479                         "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d "
480                         "found_i_mark->group=%p found_i_mark->inode=%p\n",
481                         __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group,
482                         i_mark->fsn_mark.i.inode, found_i_mark, found_i_mark->wd,
483                         found_i_mark->fsn_mark.group,
484                         found_i_mark->fsn_mark.i.inode);
485                 goto out;
486         }
487 
488         /*
489          * One ref for being in the idr
490          * one ref held by the caller trying to kill us
491          * one ref grabbed by inotify_idr_find
492          */
493         if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) {
494                 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p"
495                         " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd,
496                         i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode);
497                 /* we can't really recover with bad ref cnting.. */
498                 BUG();
499         }
500 
501         do_inotify_remove_from_idr(group, i_mark);
502 out:
503         /* match the ref taken by inotify_idr_find_locked() */
504         if (found_i_mark)
505                 fsnotify_put_mark(&found_i_mark->fsn_mark);
506         i_mark->wd = -1;
507         spin_unlock(idr_lock);
508 }
509 
510 /*
511  * Send IN_IGNORED for this wd, remove this wd from the idr.
512  */
513 void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
514                                     struct fsnotify_group *group)
515 {
516         struct inotify_inode_mark *i_mark;
517         struct fsnotify_event *ignored_event, *notify_event;
518         struct inotify_event_private_data *event_priv;
519         struct fsnotify_event_private_data *fsn_event_priv;
520         int ret;
521 
522         ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL,
523                                               FSNOTIFY_EVENT_NONE, NULL, 0,
524                                               GFP_NOFS);
525         if (!ignored_event)
526                 return;
527 
528         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
529 
530         event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS);
531         if (unlikely(!event_priv))
532                 goto skip_send_ignore;
533 
534         fsn_event_priv = &event_priv->fsnotify_event_priv_data;
535 
536         fsn_event_priv->group = group;
537         event_priv->wd = i_mark->wd;
538 
539         notify_event = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv, NULL);
540         if (notify_event) {
541                 if (IS_ERR(notify_event))
542                         ret = PTR_ERR(notify_event);
543                 else
544                         fsnotify_put_event(notify_event);
545                 inotify_free_event_priv(fsn_event_priv);
546         }
547 
548 skip_send_ignore:
549 
550         /* matches the reference taken when the event was created */
551         fsnotify_put_event(ignored_event);
552 
553         /* remove this mark from the idr */
554         inotify_remove_from_idr(group, i_mark);
555 
556         atomic_dec(&group->inotify_data.user->inotify_watches);
557 }
558 
559 /* ding dong the mark is dead */
560 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
561 {
562         struct inotify_inode_mark *i_mark;
563 
564         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
565 
566         kmem_cache_free(inotify_inode_mark_cachep, i_mark);
567 }
568 
569 static int inotify_update_existing_watch(struct fsnotify_group *group,
570                                          struct inode *inode,
571                                          u32 arg)
572 {
573         struct fsnotify_mark *fsn_mark;
574         struct inotify_inode_mark *i_mark;
575         __u32 old_mask, new_mask;
576         __u32 mask;
577         int add = (arg & IN_MASK_ADD);
578         int ret;
579 
580         mask = inotify_arg_to_mask(arg);
581 
582         fsn_mark = fsnotify_find_inode_mark(group, inode);
583         if (!fsn_mark)
584                 return -ENOENT;
585 
586         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
587 
588         spin_lock(&fsn_mark->lock);
589 
590         old_mask = fsn_mark->mask;
591         if (add)
592                 fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask));
593         else
594                 fsnotify_set_mark_mask_locked(fsn_mark, mask);
595         new_mask = fsn_mark->mask;
596 
597         spin_unlock(&fsn_mark->lock);
598 
599         if (old_mask != new_mask) {
600                 /* more bits in old than in new? */
601                 int dropped = (old_mask & ~new_mask);
602                 /* more bits in this fsn_mark than the inode's mask? */
603                 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
604 
605                 /* update the inode with this new fsn_mark */
606                 if (dropped || do_inode)
607                         fsnotify_recalc_inode_mask(inode);
608 
609         }
610 
611         /* return the wd */
612         ret = i_mark->wd;
613 
614         /* match the get from fsnotify_find_mark() */
615         fsnotify_put_mark(fsn_mark);
616 
617         return ret;
618 }
619 
620 static int inotify_new_watch(struct fsnotify_group *group,
621                              struct inode *inode,
622                              u32 arg)
623 {
624         struct inotify_inode_mark *tmp_i_mark;
625         __u32 mask;
626         int ret;
627         struct idr *idr = &group->inotify_data.idr;
628         spinlock_t *idr_lock = &group->inotify_data.idr_lock;
629 
630         mask = inotify_arg_to_mask(arg);
631 
632         tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
633         if (unlikely(!tmp_i_mark))
634                 return -ENOMEM;
635 
636         fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
637         tmp_i_mark->fsn_mark.mask = mask;
638         tmp_i_mark->wd = -1;
639 
640         ret = -ENOSPC;
641         if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
642                 goto out_err;
643 
644         ret = inotify_add_to_idr(idr, idr_lock, &group->inotify_data.last_wd,
645                                  tmp_i_mark);
646         if (ret)
647                 goto out_err;
648 
649         /* we are on the idr, now get on the inode */
650         ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0);
651         if (ret) {
652                 /* we failed to get on the inode, get off the idr */
653                 inotify_remove_from_idr(group, tmp_i_mark);
654                 goto out_err;
655         }
656 
657         /* increment the number of watches the user has */
658         atomic_inc(&group->inotify_data.user->inotify_watches);
659 
660         /* return the watch descriptor for this new mark */
661         ret = tmp_i_mark->wd;
662 
663 out_err:
664         /* match the ref from fsnotify_init_mark() */
665         fsnotify_put_mark(&tmp_i_mark->fsn_mark);
666 
667         return ret;
668 }
669 
670 static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
671 {
672         int ret = 0;
673 
674 retry:
675         /* try to update and existing watch with the new arg */
676         ret = inotify_update_existing_watch(group, inode, arg);
677         /* no mark present, try to add a new one */
678         if (ret == -ENOENT)
679                 ret = inotify_new_watch(group, inode, arg);
680         /*
681          * inotify_new_watch could race with another thread which did an
682          * inotify_new_watch between the update_existing and the add watch
683          * here, go back and try to update an existing mark again.
684          */
685         if (ret == -EEXIST)
686                 goto retry;
687 
688         return ret;
689 }
690 
691 static struct fsnotify_group *inotify_new_group(unsigned int max_events)
692 {
693         struct fsnotify_group *group;
694 
695         group = fsnotify_alloc_group(&inotify_fsnotify_ops);
696         if (IS_ERR(group))
697                 return group;
698 
699         group->max_events = max_events;
700 
701         spin_lock_init(&group->inotify_data.idr_lock);
702         idr_init(&group->inotify_data.idr);
703         group->inotify_data.last_wd = 0;
704         group->inotify_data.fa = NULL;
705         group->inotify_data.user = get_current_user();
706 
707         if (atomic_inc_return(&group->inotify_data.user->inotify_devs) >
708             inotify_max_user_instances) {
709                 fsnotify_put_group(group);
710                 return ERR_PTR(-EMFILE);
711         }
712 
713         return group;
714 }
715 
716 
717 /* inotify syscalls */
718 SYSCALL_DEFINE1(inotify_init1, int, flags)
719 {
720         struct fsnotify_group *group;
721         int ret;
722 
723         /* Check the IN_* constants for consistency.  */
724         BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
725         BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
726 
727         if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
728                 return -EINVAL;
729 
730         /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
731         group = inotify_new_group(inotify_max_queued_events);
732         if (IS_ERR(group))
733                 return PTR_ERR(group);
734 
735         ret = anon_inode_getfd("inotify", &inotify_fops, group,
736                                   O_RDONLY | flags);
737         if (ret < 0)
738                 fsnotify_put_group(group);
739 
740         return ret;
741 }
742 
743 SYSCALL_DEFINE0(inotify_init)
744 {
745         return sys_inotify_init1(0);
746 }
747 
748 SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
749                 u32, mask)
750 {
751         struct fsnotify_group *group;
752         struct inode *inode;
753         struct path path;
754         struct file *filp;
755         int ret, fput_needed;
756         unsigned flags = 0;
757 
758         /* don't allow invalid bits: we don't want flags set */
759         if (unlikely(!(mask & ALL_INOTIFY_BITS)))
760                 return -EINVAL;
761 
762         filp = fget_light(fd, &fput_needed);
763         if (unlikely(!filp))
764                 return -EBADF;
765 
766         /* verify that this is indeed an inotify instance */
767         if (unlikely(filp->f_op != &inotify_fops)) {
768                 ret = -EINVAL;
769                 goto fput_and_out;
770         }
771 
772         if (!(mask & IN_DONT_FOLLOW))
773                 flags |= LOOKUP_FOLLOW;
774         if (mask & IN_ONLYDIR)
775                 flags |= LOOKUP_DIRECTORY;
776 
777         ret = inotify_find_inode(pathname, &path, flags);
778         if (ret)
779                 goto fput_and_out;
780 
781         /* inode held in place by reference to path; group by fget on fd */
782         inode = path.dentry->d_inode;
783         group = filp->private_data;
784 
785         /* create/update an inode mark */
786         ret = inotify_update_watch(group, inode, mask);
787         path_put(&path);
788 fput_and_out:
789         fput_light(filp, fput_needed);
790         return ret;
791 }
792 
793 SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
794 {
795         struct fsnotify_group *group;
796         struct inotify_inode_mark *i_mark;
797         struct file *filp;
798         int ret = 0, fput_needed;
799 
800         filp = fget_light(fd, &fput_needed);
801         if (unlikely(!filp))
802                 return -EBADF;
803 
804         /* verify that this is indeed an inotify instance */
805         ret = -EINVAL;
806         if (unlikely(filp->f_op != &inotify_fops))
807                 goto out;
808 
809         group = filp->private_data;
810 
811         ret = -EINVAL;
812         i_mark = inotify_idr_find(group, wd);
813         if (unlikely(!i_mark))
814                 goto out;
815 
816         ret = 0;
817 
818         fsnotify_destroy_mark(&i_mark->fsn_mark);
819 
820         /* match ref taken by inotify_idr_find */
821         fsnotify_put_mark(&i_mark->fsn_mark);
822 
823 out:
824         fput_light(filp, fput_needed);
825         return ret;
826 }
827 
828 /*
829  * inotify_user_setup - Our initialization function.  Note that we cannot return
830  * error because we have compiled-in VFS hooks.  So an (unlikely) failure here
831  * must result in panic().
832  */
833 static int __init inotify_user_setup(void)
834 {
835         BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
836         BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
837         BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
838         BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
839         BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
840         BUILD_BUG_ON(IN_OPEN != FS_OPEN);
841         BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
842         BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
843         BUILD_BUG_ON(IN_CREATE != FS_CREATE);
844         BUILD_BUG_ON(IN_DELETE != FS_DELETE);
845         BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
846         BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
847         BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
848         BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
849         BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
850         BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
851         BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
852         BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
853 
854         BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
855 
856         inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
857         event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC);
858 
859         inotify_max_queued_events = 16384;
860         inotify_max_user_instances = 128;
861         inotify_max_user_watches = 8192;
862 
863         return 0;
864 }
865 module_init(inotify_user_setup);
866 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp