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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> /* 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/ */
47static int inotify_max_user_instances __read_mostly;
48static int inotify_max_queued_events __read_mostly;
49static int inotify_max_user_watches __read_mostly;
50
51static struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
52struct kmem_cache *event_priv_cachep __read_mostly;
53
54#ifdef CONFIG_SYSCTL
55
56#include <linux/sysctl.h>
57
58static int zero;
59
60ctl_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
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 */
133static 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 */
165static 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
230static 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
283static 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
290static 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
304static 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
337static 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 */
351static 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
365static 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
389static 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
410static 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
423static 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 */
442static 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);
502out:
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 */
513void 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
548skip_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 */
560static 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
569static 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 /* don't allow invalid bits: we don't want flags set */
581 mask = inotify_arg_to_mask(arg);
582 if (unlikely(!(mask & IN_ALL_EVENTS)))
583 return -EINVAL;
584
585 fsn_mark = fsnotify_find_inode_mark(group, inode);
586 if (!fsn_mark)
587 return -ENOENT;
588
589 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
590
591 spin_lock(&fsn_mark->lock);
592
593 old_mask = fsn_mark->mask;
594 if (add)
595 fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask));
596 else
597 fsnotify_set_mark_mask_locked(fsn_mark, mask);
598 new_mask = fsn_mark->mask;
599
600 spin_unlock(&fsn_mark->lock);
601
602 if (old_mask != new_mask) {
603 /* more bits in old than in new? */
604 int dropped = (old_mask & ~new_mask);
605 /* more bits in this fsn_mark than the inode's mask? */
606 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
607
608 /* update the inode with this new fsn_mark */
609 if (dropped || do_inode)
610 fsnotify_recalc_inode_mask(inode);
611
612 }
613
614 /* return the wd */
615 ret = i_mark->wd;
616
617 /* match the get from fsnotify_find_mark() */
618 fsnotify_put_mark(fsn_mark);
619
620 return ret;
621}
622
623static int inotify_new_watch(struct fsnotify_group *group,
624 struct inode *inode,
625 u32 arg)
626{
627 struct inotify_inode_mark *tmp_i_mark;
628 __u32 mask;
629 int ret;
630 struct idr *idr = &group->inotify_data.idr;
631 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
632
633 /* don't allow invalid bits: we don't want flags set */
634 mask = inotify_arg_to_mask(arg);
635 if (unlikely(!(mask & IN_ALL_EVENTS)))
636 return -EINVAL;
637
638 tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
639 if (unlikely(!tmp_i_mark))
640 return -ENOMEM;
641
642 fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark);
643 tmp_i_mark->fsn_mark.mask = mask;
644 tmp_i_mark->wd = -1;
645
646 ret = -ENOSPC;
647 if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
648 goto out_err;
649
650 ret = inotify_add_to_idr(idr, idr_lock, &group->inotify_data.last_wd,
651 tmp_i_mark);
652 if (ret)
653 goto out_err;
654
655 /* we are on the idr, now get on the inode */
656 ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0);
657 if (ret) {
658 /* we failed to get on the inode, get off the idr */
659 inotify_remove_from_idr(group, tmp_i_mark);
660 goto out_err;
661 }
662
663 /* increment the number of watches the user has */
664 atomic_inc(&group->inotify_data.user->inotify_watches);
665
666 /* return the watch descriptor for this new mark */
667 ret = tmp_i_mark->wd;
668
669out_err:
670 /* match the ref from fsnotify_init_mark() */
671 fsnotify_put_mark(&tmp_i_mark->fsn_mark);
672
673 return ret;
674}
675
676static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
677{
678 int ret = 0;
679
680retry:
681 /* try to update and existing watch with the new arg */
682 ret = inotify_update_existing_watch(group, inode, arg);
683 /* no mark present, try to add a new one */
684 if (ret == -ENOENT)
685 ret = inotify_new_watch(group, inode, arg);
686 /*
687 * inotify_new_watch could race with another thread which did an
688 * inotify_new_watch between the update_existing and the add watch
689 * here, go back and try to update an existing mark again.
690 */
691 if (ret == -EEXIST)
692 goto retry;
693
694 return ret;
695}
696
697static struct fsnotify_group *inotify_new_group(unsigned int max_events)
698{
699 struct fsnotify_group *group;
700
701 group = fsnotify_alloc_group(&inotify_fsnotify_ops);
702 if (IS_ERR(group))
703 return group;
704
705 group->max_events = max_events;
706
707 spin_lock_init(&group->inotify_data.idr_lock);
708 idr_init(&group->inotify_data.idr);
709 group->inotify_data.last_wd = 0;
710 group->inotify_data.fa = NULL;
711 group->inotify_data.user = get_current_user();
712
713 if (atomic_inc_return(&group->inotify_data.user->inotify_devs) >
714 inotify_max_user_instances) {
715 fsnotify_put_group(group);
716 return ERR_PTR(-EMFILE);
717 }
718
719 return group;
720}
721
722
723/* inotify syscalls */
724SYSCALL_DEFINE1(inotify_init1, int, flags)
725{
726 struct fsnotify_group *group;
727 int ret;
728
729 /* Check the IN_* constants for consistency. */
730 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
731 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
732
733 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
734 return -EINVAL;
735
736 /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
737 group = inotify_new_group(inotify_max_queued_events);
738 if (IS_ERR(group))
739 return PTR_ERR(group);
740
741 ret = anon_inode_getfd("inotify", &inotify_fops, group,
742 O_RDONLY | flags);
743 if (ret < 0)
744 fsnotify_put_group(group);
745
746 return ret;
747}
748
749SYSCALL_DEFINE0(inotify_init)
750{
751 return sys_inotify_init1(0);
752}
753
754SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
755 u32, mask)
756{
757 struct fsnotify_group *group;
758 struct inode *inode;
759 struct path path;
760 struct file *filp;
761 int ret, fput_needed;
762 unsigned flags = 0;
763
764 filp = fget_light(fd, &fput_needed);
765 if (unlikely(!filp))
766 return -EBADF;
767
768 /* verify that this is indeed an inotify instance */
769 if (unlikely(filp->f_op != &inotify_fops)) {
770 ret = -EINVAL;
771 goto fput_and_out;
772 }
773
774 if (!(mask & IN_DONT_FOLLOW))
775 flags |= LOOKUP_FOLLOW;
776 if (mask & IN_ONLYDIR)
777 flags |= LOOKUP_DIRECTORY;
778
779 ret = inotify_find_inode(pathname, &path, flags);
780 if (ret)
781 goto fput_and_out;
782
783 /* inode held in place by reference to path; group by fget on fd */
784 inode = path.dentry->d_inode;
785 group = filp->private_data;
786
787 /* create/update an inode mark */
788 ret = inotify_update_watch(group, inode, mask);
789 path_put(&path);
790fput_and_out:
791 fput_light(filp, fput_needed);
792 return ret;
793}
794
795SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
796{
797 struct fsnotify_group *group;
798 struct inotify_inode_mark *i_mark;
799 struct file *filp;
800 int ret = 0, fput_needed;
801
802 filp = fget_light(fd, &fput_needed);
803 if (unlikely(!filp))
804 return -EBADF;
805
806 /* verify that this is indeed an inotify instance */
807 ret = -EINVAL;
808 if (unlikely(filp->f_op != &inotify_fops))
809 goto out;
810
811 group = filp->private_data;
812
813 ret = -EINVAL;
814 i_mark = inotify_idr_find(group, wd);
815 if (unlikely(!i_mark))
816 goto out;
817
818 ret = 0;
819
820 fsnotify_destroy_mark(&i_mark->fsn_mark);
821
822 /* match ref taken by inotify_idr_find */
823 fsnotify_put_mark(&i_mark->fsn_mark);
824
825out:
826 fput_light(filp, fput_needed);
827 return ret;
828}
829
830/*
831 * inotify_user_setup - Our initialization function. Note that we cannot return
832 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
833 * must result in panic().
834 */
835static int __init inotify_user_setup(void)
836{
837 BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
838 BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
839 BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
840 BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
841 BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
842 BUILD_BUG_ON(IN_OPEN != FS_OPEN);
843 BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
844 BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
845 BUILD_BUG_ON(IN_CREATE != FS_CREATE);
846 BUILD_BUG_ON(IN_DELETE != FS_DELETE);
847 BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
848 BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
849 BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
850 BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
851 BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
852 BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
853 BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
854 BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
855
856 BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
857
858 inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
859 event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC);
860
861 inotify_max_queued_events = 16384;
862 inotify_max_user_instances = 128;
863 inotify_max_user_watches = 8192;
864
865 return 0;
866}
867module_init(inotify_user_setup);