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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> /* fs_initcall */
30#include <linux/inotify.h>
31#include <linux/kernel.h> /* roundup() */
32#include <linux/namei.h> /* LOOKUP_FOLLOW */
33#include <linux/sched/signal.h>
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/* configurable via /proc/sys/fs/inotify/ */
48static int inotify_max_queued_events __read_mostly;
49
50struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
51
52#ifdef CONFIG_SYSCTL
53
54#include <linux/sysctl.h>
55
56static int zero;
57
58struct ctl_table inotify_table[] = {
59 {
60 .procname = "max_user_instances",
61 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES],
62 .maxlen = sizeof(int),
63 .mode = 0644,
64 .proc_handler = proc_dointvec_minmax,
65 .extra1 = &zero,
66 },
67 {
68 .procname = "max_user_watches",
69 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES],
70 .maxlen = sizeof(int),
71 .mode = 0644,
72 .proc_handler = proc_dointvec_minmax,
73 .extra1 = &zero,
74 },
75 {
76 .procname = "max_queued_events",
77 .data = &inotify_max_queued_events,
78 .maxlen = sizeof(int),
79 .mode = 0644,
80 .proc_handler = proc_dointvec_minmax,
81 .extra1 = &zero
82 },
83 { }
84};
85#endif /* CONFIG_SYSCTL */
86
87static inline __u32 inotify_arg_to_mask(u32 arg)
88{
89 __u32 mask;
90
91 /*
92 * everything should accept their own ignored, cares about children,
93 * and should receive events when the inode is unmounted
94 */
95 mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);
96
97 /* mask off the flags used to open the fd */
98 mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));
99
100 return mask;
101}
102
103static inline u32 inotify_mask_to_arg(__u32 mask)
104{
105 return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED |
106 IN_Q_OVERFLOW);
107}
108
109/* intofiy userspace file descriptor functions */
110static __poll_t inotify_poll(struct file *file, poll_table *wait)
111{
112 struct fsnotify_group *group = file->private_data;
113 __poll_t ret = 0;
114
115 poll_wait(file, &group->notification_waitq, wait);
116 spin_lock(&group->notification_lock);
117 if (!fsnotify_notify_queue_is_empty(group))
118 ret = EPOLLIN | EPOLLRDNORM;
119 spin_unlock(&group->notification_lock);
120
121 return ret;
122}
123
124static int round_event_name_len(struct fsnotify_event *fsn_event)
125{
126 struct inotify_event_info *event;
127
128 event = INOTIFY_E(fsn_event);
129 if (!event->name_len)
130 return 0;
131 return roundup(event->name_len + 1, sizeof(struct inotify_event));
132}
133
134/*
135 * Get an inotify_kernel_event if one exists and is small
136 * enough to fit in "count". Return an error pointer if
137 * not large enough.
138 *
139 * Called with the group->notification_lock held.
140 */
141static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
142 size_t count)
143{
144 size_t event_size = sizeof(struct inotify_event);
145 struct fsnotify_event *event;
146
147 if (fsnotify_notify_queue_is_empty(group))
148 return NULL;
149
150 event = fsnotify_peek_first_event(group);
151
152 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
153
154 event_size += round_event_name_len(event);
155 if (event_size > count)
156 return ERR_PTR(-EINVAL);
157
158 /* held the notification_lock the whole time, so this is the
159 * same event we peeked above */
160 fsnotify_remove_first_event(group);
161
162 return event;
163}
164
165/*
166 * Copy an event to user space, returning how much we copied.
167 *
168 * We already checked that the event size is smaller than the
169 * buffer we had in "get_one_event()" above.
170 */
171static ssize_t copy_event_to_user(struct fsnotify_group *group,
172 struct fsnotify_event *fsn_event,
173 char __user *buf)
174{
175 struct inotify_event inotify_event;
176 struct inotify_event_info *event;
177 size_t event_size = sizeof(struct inotify_event);
178 size_t name_len;
179 size_t pad_name_len;
180
181 pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
182
183 event = INOTIFY_E(fsn_event);
184 name_len = event->name_len;
185 /*
186 * round up name length so it is a multiple of event_size
187 * plus an extra byte for the terminating '\0'.
188 */
189 pad_name_len = round_event_name_len(fsn_event);
190 inotify_event.len = pad_name_len;
191 inotify_event.mask = inotify_mask_to_arg(fsn_event->mask);
192 inotify_event.wd = event->wd;
193 inotify_event.cookie = event->sync_cookie;
194
195 /* send the main event */
196 if (copy_to_user(buf, &inotify_event, event_size))
197 return -EFAULT;
198
199 buf += event_size;
200
201 /*
202 * fsnotify only stores the pathname, so here we have to send the pathname
203 * and then pad that pathname out to a multiple of sizeof(inotify_event)
204 * with zeros.
205 */
206 if (pad_name_len) {
207 /* copy the path name */
208 if (copy_to_user(buf, event->name, name_len))
209 return -EFAULT;
210 buf += name_len;
211
212 /* fill userspace with 0's */
213 if (clear_user(buf, pad_name_len - name_len))
214 return -EFAULT;
215 event_size += pad_name_len;
216 }
217
218 return event_size;
219}
220
221static ssize_t inotify_read(struct file *file, char __user *buf,
222 size_t count, loff_t *pos)
223{
224 struct fsnotify_group *group;
225 struct fsnotify_event *kevent;
226 char __user *start;
227 int ret;
228 DEFINE_WAIT_FUNC(wait, woken_wake_function);
229
230 start = buf;
231 group = file->private_data;
232
233 add_wait_queue(&group->notification_waitq, &wait);
234 while (1) {
235 spin_lock(&group->notification_lock);
236 kevent = get_one_event(group, count);
237 spin_unlock(&group->notification_lock);
238
239 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
240
241 if (kevent) {
242 ret = PTR_ERR(kevent);
243 if (IS_ERR(kevent))
244 break;
245 ret = copy_event_to_user(group, kevent, buf);
246 fsnotify_destroy_event(group, kevent);
247 if (ret < 0)
248 break;
249 buf += ret;
250 count -= ret;
251 continue;
252 }
253
254 ret = -EAGAIN;
255 if (file->f_flags & O_NONBLOCK)
256 break;
257 ret = -ERESTARTSYS;
258 if (signal_pending(current))
259 break;
260
261 if (start != buf)
262 break;
263
264 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
265 }
266 remove_wait_queue(&group->notification_waitq, &wait);
267
268 if (start != buf && ret != -EFAULT)
269 ret = buf - start;
270 return ret;
271}
272
273static int inotify_release(struct inode *ignored, struct file *file)
274{
275 struct fsnotify_group *group = file->private_data;
276
277 pr_debug("%s: group=%p\n", __func__, group);
278
279 /* free this group, matching get was inotify_init->fsnotify_obtain_group */
280 fsnotify_destroy_group(group);
281
282 return 0;
283}
284
285static long inotify_ioctl(struct file *file, unsigned int cmd,
286 unsigned long arg)
287{
288 struct fsnotify_group *group;
289 struct fsnotify_event *fsn_event;
290 void __user *p;
291 int ret = -ENOTTY;
292 size_t send_len = 0;
293
294 group = file->private_data;
295 p = (void __user *) arg;
296
297 pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
298
299 switch (cmd) {
300 case FIONREAD:
301 spin_lock(&group->notification_lock);
302 list_for_each_entry(fsn_event, &group->notification_list,
303 list) {
304 send_len += sizeof(struct inotify_event);
305 send_len += round_event_name_len(fsn_event);
306 }
307 spin_unlock(&group->notification_lock);
308 ret = put_user(send_len, (int __user *) p);
309 break;
310#ifdef CONFIG_CHECKPOINT_RESTORE
311 case INOTIFY_IOC_SETNEXTWD:
312 ret = -EINVAL;
313 if (arg >= 1 && arg <= INT_MAX) {
314 struct inotify_group_private_data *data;
315
316 data = &group->inotify_data;
317 spin_lock(&data->idr_lock);
318 idr_set_cursor(&data->idr, (unsigned int)arg);
319 spin_unlock(&data->idr_lock);
320 ret = 0;
321 }
322 break;
323#endif /* CONFIG_CHECKPOINT_RESTORE */
324 }
325
326 return ret;
327}
328
329static const struct file_operations inotify_fops = {
330 .show_fdinfo = inotify_show_fdinfo,
331 .poll = inotify_poll,
332 .read = inotify_read,
333 .fasync = fsnotify_fasync,
334 .release = inotify_release,
335 .unlocked_ioctl = inotify_ioctl,
336 .compat_ioctl = inotify_ioctl,
337 .llseek = noop_llseek,
338};
339
340
341/*
342 * find_inode - resolve a user-given path to a specific inode
343 */
344static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags)
345{
346 int error;
347
348 error = user_path_at(AT_FDCWD, dirname, flags, path);
349 if (error)
350 return error;
351 /* you can only watch an inode if you have read permissions on it */
352 error = inode_permission(path->dentry->d_inode, MAY_READ);
353 if (error)
354 path_put(path);
355 return error;
356}
357
358static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
359 struct inotify_inode_mark *i_mark)
360{
361 int ret;
362
363 idr_preload(GFP_KERNEL);
364 spin_lock(idr_lock);
365
366 ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
367 if (ret >= 0) {
368 /* we added the mark to the idr, take a reference */
369 i_mark->wd = ret;
370 fsnotify_get_mark(&i_mark->fsn_mark);
371 }
372
373 spin_unlock(idr_lock);
374 idr_preload_end();
375 return ret < 0 ? ret : 0;
376}
377
378static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group,
379 int wd)
380{
381 struct idr *idr = &group->inotify_data.idr;
382 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
383 struct inotify_inode_mark *i_mark;
384
385 assert_spin_locked(idr_lock);
386
387 i_mark = idr_find(idr, wd);
388 if (i_mark) {
389 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
390
391 fsnotify_get_mark(fsn_mark);
392 /* One ref for being in the idr, one ref we just took */
393 BUG_ON(refcount_read(&fsn_mark->refcnt) < 2);
394 }
395
396 return i_mark;
397}
398
399static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
400 int wd)
401{
402 struct inotify_inode_mark *i_mark;
403 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
404
405 spin_lock(idr_lock);
406 i_mark = inotify_idr_find_locked(group, wd);
407 spin_unlock(idr_lock);
408
409 return i_mark;
410}
411
412/*
413 * Remove the mark from the idr (if present) and drop the reference
414 * on the mark because it was in the idr.
415 */
416static void inotify_remove_from_idr(struct fsnotify_group *group,
417 struct inotify_inode_mark *i_mark)
418{
419 struct idr *idr = &group->inotify_data.idr;
420 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
421 struct inotify_inode_mark *found_i_mark = NULL;
422 int wd;
423
424 spin_lock(idr_lock);
425 wd = i_mark->wd;
426
427 /*
428 * does this i_mark think it is in the idr? we shouldn't get called
429 * if it wasn't....
430 */
431 if (wd == -1) {
432 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
433 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
434 goto out;
435 }
436
437 /* Lets look in the idr to see if we find it */
438 found_i_mark = inotify_idr_find_locked(group, wd);
439 if (unlikely(!found_i_mark)) {
440 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
441 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
442 goto out;
443 }
444
445 /*
446 * We found an mark in the idr at the right wd, but it's
447 * not the mark we were told to remove. eparis seriously
448 * fucked up somewhere.
449 */
450 if (unlikely(found_i_mark != i_mark)) {
451 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
452 "found_i_mark=%p found_i_mark->wd=%d "
453 "found_i_mark->group=%p\n", __func__, i_mark,
454 i_mark->wd, i_mark->fsn_mark.group, found_i_mark,
455 found_i_mark->wd, found_i_mark->fsn_mark.group);
456 goto out;
457 }
458
459 /*
460 * One ref for being in the idr
461 * one ref grabbed by inotify_idr_find
462 */
463 if (unlikely(refcount_read(&i_mark->fsn_mark.refcnt) < 2)) {
464 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
465 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
466 /* we can't really recover with bad ref cnting.. */
467 BUG();
468 }
469
470 idr_remove(idr, wd);
471 /* Removed from the idr, drop that ref. */
472 fsnotify_put_mark(&i_mark->fsn_mark);
473out:
474 i_mark->wd = -1;
475 spin_unlock(idr_lock);
476 /* match the ref taken by inotify_idr_find_locked() */
477 if (found_i_mark)
478 fsnotify_put_mark(&found_i_mark->fsn_mark);
479}
480
481/*
482 * Send IN_IGNORED for this wd, remove this wd from the idr.
483 */
484void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
485 struct fsnotify_group *group)
486{
487 struct inotify_inode_mark *i_mark;
488
489 /* Queue ignore event for the watch */
490 inotify_handle_event(group, NULL, fsn_mark, NULL, FS_IN_IGNORED,
491 NULL, FSNOTIFY_EVENT_NONE, NULL, 0, NULL);
492
493 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
494 /* remove this mark from the idr */
495 inotify_remove_from_idr(group, i_mark);
496
497 dec_inotify_watches(group->inotify_data.ucounts);
498}
499
500static int inotify_update_existing_watch(struct fsnotify_group *group,
501 struct inode *inode,
502 u32 arg)
503{
504 struct fsnotify_mark *fsn_mark;
505 struct inotify_inode_mark *i_mark;
506 __u32 old_mask, new_mask;
507 __u32 mask;
508 int add = (arg & IN_MASK_ADD);
509 int ret;
510
511 mask = inotify_arg_to_mask(arg);
512
513 fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
514 if (!fsn_mark)
515 return -ENOENT;
516
517 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
518
519 spin_lock(&fsn_mark->lock);
520 old_mask = fsn_mark->mask;
521 if (add)
522 fsn_mark->mask |= mask;
523 else
524 fsn_mark->mask = mask;
525 new_mask = fsn_mark->mask;
526 spin_unlock(&fsn_mark->lock);
527
528 if (old_mask != new_mask) {
529 /* more bits in old than in new? */
530 int dropped = (old_mask & ~new_mask);
531 /* more bits in this fsn_mark than the inode's mask? */
532 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
533
534 /* update the inode with this new fsn_mark */
535 if (dropped || do_inode)
536 fsnotify_recalc_mask(inode->i_fsnotify_marks);
537
538 }
539
540 /* return the wd */
541 ret = i_mark->wd;
542
543 /* match the get from fsnotify_find_mark() */
544 fsnotify_put_mark(fsn_mark);
545
546 return ret;
547}
548
549static int inotify_new_watch(struct fsnotify_group *group,
550 struct inode *inode,
551 u32 arg)
552{
553 struct inotify_inode_mark *tmp_i_mark;
554 __u32 mask;
555 int ret;
556 struct idr *idr = &group->inotify_data.idr;
557 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
558
559 mask = inotify_arg_to_mask(arg);
560
561 tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
562 if (unlikely(!tmp_i_mark))
563 return -ENOMEM;
564
565 fsnotify_init_mark(&tmp_i_mark->fsn_mark, group);
566 tmp_i_mark->fsn_mark.mask = mask;
567 tmp_i_mark->wd = -1;
568
569 ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
570 if (ret)
571 goto out_err;
572
573 /* increment the number of watches the user has */
574 if (!inc_inotify_watches(group->inotify_data.ucounts)) {
575 inotify_remove_from_idr(group, tmp_i_mark);
576 ret = -ENOSPC;
577 goto out_err;
578 }
579
580 /* we are on the idr, now get on the inode */
581 ret = fsnotify_add_mark_locked(&tmp_i_mark->fsn_mark, inode, NULL, 0);
582 if (ret) {
583 /* we failed to get on the inode, get off the idr */
584 inotify_remove_from_idr(group, tmp_i_mark);
585 goto out_err;
586 }
587
588
589 /* return the watch descriptor for this new mark */
590 ret = tmp_i_mark->wd;
591
592out_err:
593 /* match the ref from fsnotify_init_mark() */
594 fsnotify_put_mark(&tmp_i_mark->fsn_mark);
595
596 return ret;
597}
598
599static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
600{
601 int ret = 0;
602
603 mutex_lock(&group->mark_mutex);
604 /* try to update and existing watch with the new arg */
605 ret = inotify_update_existing_watch(group, inode, arg);
606 /* no mark present, try to add a new one */
607 if (ret == -ENOENT)
608 ret = inotify_new_watch(group, inode, arg);
609 mutex_unlock(&group->mark_mutex);
610
611 return ret;
612}
613
614static struct fsnotify_group *inotify_new_group(unsigned int max_events)
615{
616 struct fsnotify_group *group;
617 struct inotify_event_info *oevent;
618
619 group = fsnotify_alloc_group(&inotify_fsnotify_ops);
620 if (IS_ERR(group))
621 return group;
622
623 oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
624 if (unlikely(!oevent)) {
625 fsnotify_destroy_group(group);
626 return ERR_PTR(-ENOMEM);
627 }
628 group->overflow_event = &oevent->fse;
629 fsnotify_init_event(group->overflow_event, NULL, FS_Q_OVERFLOW);
630 oevent->wd = -1;
631 oevent->sync_cookie = 0;
632 oevent->name_len = 0;
633
634 group->max_events = max_events;
635
636 spin_lock_init(&group->inotify_data.idr_lock);
637 idr_init(&group->inotify_data.idr);
638 group->inotify_data.ucounts = inc_ucount(current_user_ns(),
639 current_euid(),
640 UCOUNT_INOTIFY_INSTANCES);
641
642 if (!group->inotify_data.ucounts) {
643 fsnotify_destroy_group(group);
644 return ERR_PTR(-EMFILE);
645 }
646
647 return group;
648}
649
650
651/* inotify syscalls */
652static int do_inotify_init(int flags)
653{
654 struct fsnotify_group *group;
655 int ret;
656
657 /* Check the IN_* constants for consistency. */
658 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
659 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
660
661 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
662 return -EINVAL;
663
664 /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
665 group = inotify_new_group(inotify_max_queued_events);
666 if (IS_ERR(group))
667 return PTR_ERR(group);
668
669 ret = anon_inode_getfd("inotify", &inotify_fops, group,
670 O_RDONLY | flags);
671 if (ret < 0)
672 fsnotify_destroy_group(group);
673
674 return ret;
675}
676
677SYSCALL_DEFINE1(inotify_init1, int, flags)
678{
679 return do_inotify_init(flags);
680}
681
682SYSCALL_DEFINE0(inotify_init)
683{
684 return do_inotify_init(0);
685}
686
687SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
688 u32, mask)
689{
690 struct fsnotify_group *group;
691 struct inode *inode;
692 struct path path;
693 struct fd f;
694 int ret;
695 unsigned flags = 0;
696
697 /*
698 * We share a lot of code with fs/dnotify. We also share
699 * the bit layout between inotify's IN_* and the fsnotify
700 * FS_*. This check ensures that only the inotify IN_*
701 * bits get passed in and set in watches/events.
702 */
703 if (unlikely(mask & ~ALL_INOTIFY_BITS))
704 return -EINVAL;
705 /*
706 * Require at least one valid bit set in the mask.
707 * Without _something_ set, we would have no events to
708 * watch for.
709 */
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);
739fput_and_out:
740 fdput(f);
741 return ret;
742}
743
744SYSCALL_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
774out:
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 */
784static 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 init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
811 init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192;
812
813 return 0;
814}
815fs_initcall(inotify_user_setup);
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> /* fs_initcall */
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/ */
48static int inotify_max_user_instances __read_mostly;
49static int inotify_max_queued_events __read_mostly;
50static int inotify_max_user_watches __read_mostly;
51
52static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
53
54#ifdef CONFIG_SYSCTL
55
56#include <linux/sysctl.h>
57
58static int zero;
59
60struct 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
89static 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
105static 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 */
112static 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
126static 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 */
143static 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 */
173static 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
223static 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
275static 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
287static 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
317static 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 */
332static 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
346static 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
366static 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
387static 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
400static 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 */
419static 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);
479out:
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 */
490void 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 */
507static 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
516static 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
567static 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
610out_err:
611 /* match the ref from fsnotify_init_mark() */
612 fsnotify_put_mark(&tmp_i_mark->fsn_mark);
613
614 return ret;
615}
616
617static 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
632static 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 */
669SYSCALL_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
694SYSCALL_DEFINE0(inotify_init)
695{
696 return sys_inotify_init1(0);
697}
698
699SYSCALL_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 /*
710 * We share a lot of code with fs/dnotify. We also share
711 * the bit layout between inotify's IN_* and the fsnotify
712 * FS_*. This check ensures that only the inotify IN_*
713 * bits get passed in and set in watches/events.
714 */
715 if (unlikely(mask & ~ALL_INOTIFY_BITS))
716 return -EINVAL;
717 /*
718 * Require at least one valid bit set in the mask.
719 * Without _something_ set, we would have no events to
720 * watch for.
721 */
722 if (unlikely(!(mask & ALL_INOTIFY_BITS)))
723 return -EINVAL;
724
725 f = fdget(fd);
726 if (unlikely(!f.file))
727 return -EBADF;
728
729 /* verify that this is indeed an inotify instance */
730 if (unlikely(f.file->f_op != &inotify_fops)) {
731 ret = -EINVAL;
732 goto fput_and_out;
733 }
734
735 if (!(mask & IN_DONT_FOLLOW))
736 flags |= LOOKUP_FOLLOW;
737 if (mask & IN_ONLYDIR)
738 flags |= LOOKUP_DIRECTORY;
739
740 ret = inotify_find_inode(pathname, &path, flags);
741 if (ret)
742 goto fput_and_out;
743
744 /* inode held in place by reference to path; group by fget on fd */
745 inode = path.dentry->d_inode;
746 group = f.file->private_data;
747
748 /* create/update an inode mark */
749 ret = inotify_update_watch(group, inode, mask);
750 path_put(&path);
751fput_and_out:
752 fdput(f);
753 return ret;
754}
755
756SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
757{
758 struct fsnotify_group *group;
759 struct inotify_inode_mark *i_mark;
760 struct fd f;
761 int ret = 0;
762
763 f = fdget(fd);
764 if (unlikely(!f.file))
765 return -EBADF;
766
767 /* verify that this is indeed an inotify instance */
768 ret = -EINVAL;
769 if (unlikely(f.file->f_op != &inotify_fops))
770 goto out;
771
772 group = f.file->private_data;
773
774 ret = -EINVAL;
775 i_mark = inotify_idr_find(group, wd);
776 if (unlikely(!i_mark))
777 goto out;
778
779 ret = 0;
780
781 fsnotify_destroy_mark(&i_mark->fsn_mark, group);
782
783 /* match ref taken by inotify_idr_find */
784 fsnotify_put_mark(&i_mark->fsn_mark);
785
786out:
787 fdput(f);
788 return ret;
789}
790
791/*
792 * inotify_user_setup - Our initialization function. Note that we cannot return
793 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
794 * must result in panic().
795 */
796static int __init inotify_user_setup(void)
797{
798 BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
799 BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
800 BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
801 BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
802 BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
803 BUILD_BUG_ON(IN_OPEN != FS_OPEN);
804 BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
805 BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
806 BUILD_BUG_ON(IN_CREATE != FS_CREATE);
807 BUILD_BUG_ON(IN_DELETE != FS_DELETE);
808 BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
809 BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
810 BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
811 BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
812 BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
813 BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
814 BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
815 BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
816
817 BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
818
819 inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
820
821 inotify_max_queued_events = 16384;
822 inotify_max_user_instances = 128;
823 inotify_max_user_watches = 8192;
824
825 return 0;
826}
827fs_initcall(inotify_user_setup);