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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// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * fs/inotify_user.c - inotify support for userspace
4 *
5 * Authors:
6 * John McCutchan <ttb@tentacle.dhs.org>
7 * Robert Love <rml@novell.com>
8 *
9 * Copyright (C) 2005 John McCutchan
10 * Copyright 2006 Hewlett-Packard Development Company, L.P.
11 *
12 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
13 * inotify was largely rewriten to make use of the fsnotify infrastructure
14 */
15
16#include <linux/file.h>
17#include <linux/fs.h> /* struct inode */
18#include <linux/fsnotify_backend.h>
19#include <linux/idr.h>
20#include <linux/init.h> /* fs_initcall */
21#include <linux/inotify.h>
22#include <linux/kernel.h> /* roundup() */
23#include <linux/namei.h> /* LOOKUP_FOLLOW */
24#include <linux/sched/signal.h>
25#include <linux/slab.h> /* struct kmem_cache */
26#include <linux/syscalls.h>
27#include <linux/types.h>
28#include <linux/anon_inodes.h>
29#include <linux/uaccess.h>
30#include <linux/poll.h>
31#include <linux/wait.h>
32#include <linux/memcontrol.h>
33#include <linux/security.h>
34
35#include "inotify.h"
36#include "../fdinfo.h"
37
38#include <asm/ioctls.h>
39
40/* configurable via /proc/sys/fs/inotify/ */
41static int inotify_max_queued_events __read_mostly;
42
43struct kmem_cache *inotify_inode_mark_cachep __read_mostly;
44
45#ifdef CONFIG_SYSCTL
46
47#include <linux/sysctl.h>
48
49struct ctl_table inotify_table[] = {
50 {
51 .procname = "max_user_instances",
52 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES],
53 .maxlen = sizeof(int),
54 .mode = 0644,
55 .proc_handler = proc_dointvec_minmax,
56 .extra1 = SYSCTL_ZERO,
57 },
58 {
59 .procname = "max_user_watches",
60 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES],
61 .maxlen = sizeof(int),
62 .mode = 0644,
63 .proc_handler = proc_dointvec_minmax,
64 .extra1 = SYSCTL_ZERO,
65 },
66 {
67 .procname = "max_queued_events",
68 .data = &inotify_max_queued_events,
69 .maxlen = sizeof(int),
70 .mode = 0644,
71 .proc_handler = proc_dointvec_minmax,
72 .extra1 = SYSCTL_ZERO
73 },
74 { }
75};
76#endif /* CONFIG_SYSCTL */
77
78static inline __u32 inotify_arg_to_mask(u32 arg)
79{
80 __u32 mask;
81
82 /*
83 * everything should accept their own ignored, cares about children,
84 * and should receive events when the inode is unmounted
85 */
86 mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT);
87
88 /* mask off the flags used to open the fd */
89 mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK));
90
91 return mask;
92}
93
94static inline u32 inotify_mask_to_arg(__u32 mask)
95{
96 return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED |
97 IN_Q_OVERFLOW);
98}
99
100/* intofiy userspace file descriptor functions */
101static __poll_t inotify_poll(struct file *file, poll_table *wait)
102{
103 struct fsnotify_group *group = file->private_data;
104 __poll_t ret = 0;
105
106 poll_wait(file, &group->notification_waitq, wait);
107 spin_lock(&group->notification_lock);
108 if (!fsnotify_notify_queue_is_empty(group))
109 ret = EPOLLIN | EPOLLRDNORM;
110 spin_unlock(&group->notification_lock);
111
112 return ret;
113}
114
115static int round_event_name_len(struct fsnotify_event *fsn_event)
116{
117 struct inotify_event_info *event;
118
119 event = INOTIFY_E(fsn_event);
120 if (!event->name_len)
121 return 0;
122 return roundup(event->name_len + 1, sizeof(struct inotify_event));
123}
124
125/*
126 * Get an inotify_kernel_event if one exists and is small
127 * enough to fit in "count". Return an error pointer if
128 * not large enough.
129 *
130 * Called with the group->notification_lock held.
131 */
132static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
133 size_t count)
134{
135 size_t event_size = sizeof(struct inotify_event);
136 struct fsnotify_event *event;
137
138 if (fsnotify_notify_queue_is_empty(group))
139 return NULL;
140
141 event = fsnotify_peek_first_event(group);
142
143 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
144
145 event_size += round_event_name_len(event);
146 if (event_size > count)
147 return ERR_PTR(-EINVAL);
148
149 /* held the notification_lock the whole time, so this is the
150 * same event we peeked above */
151 fsnotify_remove_first_event(group);
152
153 return event;
154}
155
156/*
157 * Copy an event to user space, returning how much we copied.
158 *
159 * We already checked that the event size is smaller than the
160 * buffer we had in "get_one_event()" above.
161 */
162static ssize_t copy_event_to_user(struct fsnotify_group *group,
163 struct fsnotify_event *fsn_event,
164 char __user *buf)
165{
166 struct inotify_event inotify_event;
167 struct inotify_event_info *event;
168 size_t event_size = sizeof(struct inotify_event);
169 size_t name_len;
170 size_t pad_name_len;
171
172 pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event);
173
174 event = INOTIFY_E(fsn_event);
175 name_len = event->name_len;
176 /*
177 * round up name length so it is a multiple of event_size
178 * plus an extra byte for the terminating '\0'.
179 */
180 pad_name_len = round_event_name_len(fsn_event);
181 inotify_event.len = pad_name_len;
182 inotify_event.mask = inotify_mask_to_arg(event->mask);
183 inotify_event.wd = event->wd;
184 inotify_event.cookie = event->sync_cookie;
185
186 /* send the main event */
187 if (copy_to_user(buf, &inotify_event, event_size))
188 return -EFAULT;
189
190 buf += event_size;
191
192 /*
193 * fsnotify only stores the pathname, so here we have to send the pathname
194 * and then pad that pathname out to a multiple of sizeof(inotify_event)
195 * with zeros.
196 */
197 if (pad_name_len) {
198 /* copy the path name */
199 if (copy_to_user(buf, event->name, name_len))
200 return -EFAULT;
201 buf += name_len;
202
203 /* fill userspace with 0's */
204 if (clear_user(buf, pad_name_len - name_len))
205 return -EFAULT;
206 event_size += pad_name_len;
207 }
208
209 return event_size;
210}
211
212static ssize_t inotify_read(struct file *file, char __user *buf,
213 size_t count, loff_t *pos)
214{
215 struct fsnotify_group *group;
216 struct fsnotify_event *kevent;
217 char __user *start;
218 int ret;
219 DEFINE_WAIT_FUNC(wait, woken_wake_function);
220
221 start = buf;
222 group = file->private_data;
223
224 add_wait_queue(&group->notification_waitq, &wait);
225 while (1) {
226 spin_lock(&group->notification_lock);
227 kevent = get_one_event(group, count);
228 spin_unlock(&group->notification_lock);
229
230 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent);
231
232 if (kevent) {
233 ret = PTR_ERR(kevent);
234 if (IS_ERR(kevent))
235 break;
236 ret = copy_event_to_user(group, kevent, buf);
237 fsnotify_destroy_event(group, kevent);
238 if (ret < 0)
239 break;
240 buf += ret;
241 count -= ret;
242 continue;
243 }
244
245 ret = -EAGAIN;
246 if (file->f_flags & O_NONBLOCK)
247 break;
248 ret = -ERESTARTSYS;
249 if (signal_pending(current))
250 break;
251
252 if (start != buf)
253 break;
254
255 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
256 }
257 remove_wait_queue(&group->notification_waitq, &wait);
258
259 if (start != buf && ret != -EFAULT)
260 ret = buf - start;
261 return ret;
262}
263
264static int inotify_release(struct inode *ignored, struct file *file)
265{
266 struct fsnotify_group *group = file->private_data;
267
268 pr_debug("%s: group=%p\n", __func__, group);
269
270 /* free this group, matching get was inotify_init->fsnotify_obtain_group */
271 fsnotify_destroy_group(group);
272
273 return 0;
274}
275
276static long inotify_ioctl(struct file *file, unsigned int cmd,
277 unsigned long arg)
278{
279 struct fsnotify_group *group;
280 struct fsnotify_event *fsn_event;
281 void __user *p;
282 int ret = -ENOTTY;
283 size_t send_len = 0;
284
285 group = file->private_data;
286 p = (void __user *) arg;
287
288 pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd);
289
290 switch (cmd) {
291 case FIONREAD:
292 spin_lock(&group->notification_lock);
293 list_for_each_entry(fsn_event, &group->notification_list,
294 list) {
295 send_len += sizeof(struct inotify_event);
296 send_len += round_event_name_len(fsn_event);
297 }
298 spin_unlock(&group->notification_lock);
299 ret = put_user(send_len, (int __user *) p);
300 break;
301#ifdef CONFIG_CHECKPOINT_RESTORE
302 case INOTIFY_IOC_SETNEXTWD:
303 ret = -EINVAL;
304 if (arg >= 1 && arg <= INT_MAX) {
305 struct inotify_group_private_data *data;
306
307 data = &group->inotify_data;
308 spin_lock(&data->idr_lock);
309 idr_set_cursor(&data->idr, (unsigned int)arg);
310 spin_unlock(&data->idr_lock);
311 ret = 0;
312 }
313 break;
314#endif /* CONFIG_CHECKPOINT_RESTORE */
315 }
316
317 return ret;
318}
319
320static const struct file_operations inotify_fops = {
321 .show_fdinfo = inotify_show_fdinfo,
322 .poll = inotify_poll,
323 .read = inotify_read,
324 .fasync = fsnotify_fasync,
325 .release = inotify_release,
326 .unlocked_ioctl = inotify_ioctl,
327 .compat_ioctl = inotify_ioctl,
328 .llseek = noop_llseek,
329};
330
331
332/*
333 * find_inode - resolve a user-given path to a specific inode
334 */
335static int inotify_find_inode(const char __user *dirname, struct path *path,
336 unsigned int flags, __u64 mask)
337{
338 int error;
339
340 error = user_path_at(AT_FDCWD, dirname, flags, path);
341 if (error)
342 return error;
343 /* you can only watch an inode if you have read permissions on it */
344 error = inode_permission(path->dentry->d_inode, MAY_READ);
345 if (error) {
346 path_put(path);
347 return error;
348 }
349 error = security_path_notify(path, mask,
350 FSNOTIFY_OBJ_TYPE_INODE);
351 if (error)
352 path_put(path);
353
354 return error;
355}
356
357static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
358 struct inotify_inode_mark *i_mark)
359{
360 int ret;
361
362 idr_preload(GFP_KERNEL);
363 spin_lock(idr_lock);
364
365 ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
366 if (ret >= 0) {
367 /* we added the mark to the idr, take a reference */
368 i_mark->wd = ret;
369 fsnotify_get_mark(&i_mark->fsn_mark);
370 }
371
372 spin_unlock(idr_lock);
373 idr_preload_end();
374 return ret < 0 ? ret : 0;
375}
376
377static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group,
378 int wd)
379{
380 struct idr *idr = &group->inotify_data.idr;
381 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
382 struct inotify_inode_mark *i_mark;
383
384 assert_spin_locked(idr_lock);
385
386 i_mark = idr_find(idr, wd);
387 if (i_mark) {
388 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark;
389
390 fsnotify_get_mark(fsn_mark);
391 /* One ref for being in the idr, one ref we just took */
392 BUG_ON(refcount_read(&fsn_mark->refcnt) < 2);
393 }
394
395 return i_mark;
396}
397
398static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group,
399 int wd)
400{
401 struct inotify_inode_mark *i_mark;
402 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
403
404 spin_lock(idr_lock);
405 i_mark = inotify_idr_find_locked(group, wd);
406 spin_unlock(idr_lock);
407
408 return i_mark;
409}
410
411/*
412 * Remove the mark from the idr (if present) and drop the reference
413 * on the mark because it was in the idr.
414 */
415static void inotify_remove_from_idr(struct fsnotify_group *group,
416 struct inotify_inode_mark *i_mark)
417{
418 struct idr *idr = &group->inotify_data.idr;
419 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
420 struct inotify_inode_mark *found_i_mark = NULL;
421 int wd;
422
423 spin_lock(idr_lock);
424 wd = i_mark->wd;
425
426 /*
427 * does this i_mark think it is in the idr? we shouldn't get called
428 * if it wasn't....
429 */
430 if (wd == -1) {
431 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
432 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
433 goto out;
434 }
435
436 /* Lets look in the idr to see if we find it */
437 found_i_mark = inotify_idr_find_locked(group, wd);
438 if (unlikely(!found_i_mark)) {
439 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
440 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
441 goto out;
442 }
443
444 /*
445 * We found an mark in the idr at the right wd, but it's
446 * not the mark we were told to remove. eparis seriously
447 * fucked up somewhere.
448 */
449 if (unlikely(found_i_mark != i_mark)) {
450 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p "
451 "found_i_mark=%p found_i_mark->wd=%d "
452 "found_i_mark->group=%p\n", __func__, i_mark,
453 i_mark->wd, i_mark->fsn_mark.group, found_i_mark,
454 found_i_mark->wd, found_i_mark->fsn_mark.group);
455 goto out;
456 }
457
458 /*
459 * One ref for being in the idr
460 * one ref grabbed by inotify_idr_find
461 */
462 if (unlikely(refcount_read(&i_mark->fsn_mark.refcnt) < 2)) {
463 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n",
464 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group);
465 /* we can't really recover with bad ref cnting.. */
466 BUG();
467 }
468
469 idr_remove(idr, wd);
470 /* Removed from the idr, drop that ref. */
471 fsnotify_put_mark(&i_mark->fsn_mark);
472out:
473 i_mark->wd = -1;
474 spin_unlock(idr_lock);
475 /* match the ref taken by inotify_idr_find_locked() */
476 if (found_i_mark)
477 fsnotify_put_mark(&found_i_mark->fsn_mark);
478}
479
480/*
481 * Send IN_IGNORED for this wd, remove this wd from the idr.
482 */
483void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark,
484 struct fsnotify_group *group)
485{
486 struct inotify_inode_mark *i_mark;
487 struct fsnotify_iter_info iter_info = { };
488
489 fsnotify_iter_set_report_type_mark(&iter_info, FSNOTIFY_OBJ_TYPE_INODE,
490 fsn_mark);
491
492 /* Queue ignore event for the watch */
493 inotify_handle_event(group, NULL, FS_IN_IGNORED, NULL,
494 FSNOTIFY_EVENT_NONE, NULL, 0, &iter_info);
495
496 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
497 /* remove this mark from the idr */
498 inotify_remove_from_idr(group, i_mark);
499
500 dec_inotify_watches(group->inotify_data.ucounts);
501}
502
503static int inotify_update_existing_watch(struct fsnotify_group *group,
504 struct inode *inode,
505 u32 arg)
506{
507 struct fsnotify_mark *fsn_mark;
508 struct inotify_inode_mark *i_mark;
509 __u32 old_mask, new_mask;
510 __u32 mask;
511 int add = (arg & IN_MASK_ADD);
512 int create = (arg & IN_MASK_CREATE);
513 int ret;
514
515 mask = inotify_arg_to_mask(arg);
516
517 fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
518 if (!fsn_mark)
519 return -ENOENT;
520 else if (create) {
521 ret = -EEXIST;
522 goto out;
523 }
524
525 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
526
527 spin_lock(&fsn_mark->lock);
528 old_mask = fsn_mark->mask;
529 if (add)
530 fsn_mark->mask |= mask;
531 else
532 fsn_mark->mask = mask;
533 new_mask = fsn_mark->mask;
534 spin_unlock(&fsn_mark->lock);
535
536 if (old_mask != new_mask) {
537 /* more bits in old than in new? */
538 int dropped = (old_mask & ~new_mask);
539 /* more bits in this fsn_mark than the inode's mask? */
540 int do_inode = (new_mask & ~inode->i_fsnotify_mask);
541
542 /* update the inode with this new fsn_mark */
543 if (dropped || do_inode)
544 fsnotify_recalc_mask(inode->i_fsnotify_marks);
545
546 }
547
548 /* return the wd */
549 ret = i_mark->wd;
550
551out:
552 /* match the get from fsnotify_find_mark() */
553 fsnotify_put_mark(fsn_mark);
554
555 return ret;
556}
557
558static int inotify_new_watch(struct fsnotify_group *group,
559 struct inode *inode,
560 u32 arg)
561{
562 struct inotify_inode_mark *tmp_i_mark;
563 __u32 mask;
564 int ret;
565 struct idr *idr = &group->inotify_data.idr;
566 spinlock_t *idr_lock = &group->inotify_data.idr_lock;
567
568 mask = inotify_arg_to_mask(arg);
569
570 tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL);
571 if (unlikely(!tmp_i_mark))
572 return -ENOMEM;
573
574 fsnotify_init_mark(&tmp_i_mark->fsn_mark, group);
575 tmp_i_mark->fsn_mark.mask = mask;
576 tmp_i_mark->wd = -1;
577
578 ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
579 if (ret)
580 goto out_err;
581
582 /* increment the number of watches the user has */
583 if (!inc_inotify_watches(group->inotify_data.ucounts)) {
584 inotify_remove_from_idr(group, tmp_i_mark);
585 ret = -ENOSPC;
586 goto out_err;
587 }
588
589 /* we are on the idr, now get on the inode */
590 ret = fsnotify_add_inode_mark_locked(&tmp_i_mark->fsn_mark, inode, 0);
591 if (ret) {
592 /* we failed to get on the inode, get off the idr */
593 inotify_remove_from_idr(group, tmp_i_mark);
594 goto out_err;
595 }
596
597
598 /* return the watch descriptor for this new mark */
599 ret = tmp_i_mark->wd;
600
601out_err:
602 /* match the ref from fsnotify_init_mark() */
603 fsnotify_put_mark(&tmp_i_mark->fsn_mark);
604
605 return ret;
606}
607
608static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg)
609{
610 int ret = 0;
611
612 mutex_lock(&group->mark_mutex);
613 /* try to update and existing watch with the new arg */
614 ret = inotify_update_existing_watch(group, inode, arg);
615 /* no mark present, try to add a new one */
616 if (ret == -ENOENT)
617 ret = inotify_new_watch(group, inode, arg);
618 mutex_unlock(&group->mark_mutex);
619
620 return ret;
621}
622
623static struct fsnotify_group *inotify_new_group(unsigned int max_events)
624{
625 struct fsnotify_group *group;
626 struct inotify_event_info *oevent;
627
628 group = fsnotify_alloc_group(&inotify_fsnotify_ops);
629 if (IS_ERR(group))
630 return group;
631
632 oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL);
633 if (unlikely(!oevent)) {
634 fsnotify_destroy_group(group);
635 return ERR_PTR(-ENOMEM);
636 }
637 group->overflow_event = &oevent->fse;
638 fsnotify_init_event(group->overflow_event, NULL);
639 oevent->mask = FS_Q_OVERFLOW;
640 oevent->wd = -1;
641 oevent->sync_cookie = 0;
642 oevent->name_len = 0;
643
644 group->max_events = max_events;
645 group->memcg = get_mem_cgroup_from_mm(current->mm);
646
647 spin_lock_init(&group->inotify_data.idr_lock);
648 idr_init(&group->inotify_data.idr);
649 group->inotify_data.ucounts = inc_ucount(current_user_ns(),
650 current_euid(),
651 UCOUNT_INOTIFY_INSTANCES);
652
653 if (!group->inotify_data.ucounts) {
654 fsnotify_destroy_group(group);
655 return ERR_PTR(-EMFILE);
656 }
657
658 return group;
659}
660
661
662/* inotify syscalls */
663static int do_inotify_init(int flags)
664{
665 struct fsnotify_group *group;
666 int ret;
667
668 /* Check the IN_* constants for consistency. */
669 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
670 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
671
672 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
673 return -EINVAL;
674
675 /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */
676 group = inotify_new_group(inotify_max_queued_events);
677 if (IS_ERR(group))
678 return PTR_ERR(group);
679
680 ret = anon_inode_getfd("inotify", &inotify_fops, group,
681 O_RDONLY | flags);
682 if (ret < 0)
683 fsnotify_destroy_group(group);
684
685 return ret;
686}
687
688SYSCALL_DEFINE1(inotify_init1, int, flags)
689{
690 return do_inotify_init(flags);
691}
692
693SYSCALL_DEFINE0(inotify_init)
694{
695 return do_inotify_init(0);
696}
697
698SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname,
699 u32, mask)
700{
701 struct fsnotify_group *group;
702 struct inode *inode;
703 struct path path;
704 struct fd f;
705 int ret;
706 unsigned flags = 0;
707
708 /*
709 * We share a lot of code with fs/dnotify. We also share
710 * the bit layout between inotify's IN_* and the fsnotify
711 * FS_*. This check ensures that only the inotify IN_*
712 * bits get passed in and set in watches/events.
713 */
714 if (unlikely(mask & ~ALL_INOTIFY_BITS))
715 return -EINVAL;
716 /*
717 * Require at least one valid bit set in the mask.
718 * Without _something_ set, we would have no events to
719 * watch for.
720 */
721 if (unlikely(!(mask & ALL_INOTIFY_BITS)))
722 return -EINVAL;
723
724 f = fdget(fd);
725 if (unlikely(!f.file))
726 return -EBADF;
727
728 /* IN_MASK_ADD and IN_MASK_CREATE don't make sense together */
729 if (unlikely((mask & IN_MASK_ADD) && (mask & IN_MASK_CREATE))) {
730 ret = -EINVAL;
731 goto fput_and_out;
732 }
733
734 /* verify that this is indeed an inotify instance */
735 if (unlikely(f.file->f_op != &inotify_fops)) {
736 ret = -EINVAL;
737 goto fput_and_out;
738 }
739
740 if (!(mask & IN_DONT_FOLLOW))
741 flags |= LOOKUP_FOLLOW;
742 if (mask & IN_ONLYDIR)
743 flags |= LOOKUP_DIRECTORY;
744
745 ret = inotify_find_inode(pathname, &path, flags,
746 (mask & IN_ALL_EVENTS));
747 if (ret)
748 goto fput_and_out;
749
750 /* inode held in place by reference to path; group by fget on fd */
751 inode = path.dentry->d_inode;
752 group = f.file->private_data;
753
754 /* create/update an inode mark */
755 ret = inotify_update_watch(group, inode, mask);
756 path_put(&path);
757fput_and_out:
758 fdput(f);
759 return ret;
760}
761
762SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
763{
764 struct fsnotify_group *group;
765 struct inotify_inode_mark *i_mark;
766 struct fd f;
767 int ret = 0;
768
769 f = fdget(fd);
770 if (unlikely(!f.file))
771 return -EBADF;
772
773 /* verify that this is indeed an inotify instance */
774 ret = -EINVAL;
775 if (unlikely(f.file->f_op != &inotify_fops))
776 goto out;
777
778 group = f.file->private_data;
779
780 ret = -EINVAL;
781 i_mark = inotify_idr_find(group, wd);
782 if (unlikely(!i_mark))
783 goto out;
784
785 ret = 0;
786
787 fsnotify_destroy_mark(&i_mark->fsn_mark, group);
788
789 /* match ref taken by inotify_idr_find */
790 fsnotify_put_mark(&i_mark->fsn_mark);
791
792out:
793 fdput(f);
794 return ret;
795}
796
797/*
798 * inotify_user_setup - Our initialization function. Note that we cannot return
799 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
800 * must result in panic().
801 */
802static int __init inotify_user_setup(void)
803{
804 BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
805 BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
806 BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
807 BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE);
808 BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE);
809 BUILD_BUG_ON(IN_OPEN != FS_OPEN);
810 BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM);
811 BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO);
812 BUILD_BUG_ON(IN_CREATE != FS_CREATE);
813 BUILD_BUG_ON(IN_DELETE != FS_DELETE);
814 BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF);
815 BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF);
816 BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT);
817 BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW);
818 BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED);
819 BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK);
820 BUILD_BUG_ON(IN_ISDIR != FS_ISDIR);
821 BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT);
822
823 BUILD_BUG_ON(HWEIGHT32(ALL_INOTIFY_BITS) != 22);
824
825 inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark,
826 SLAB_PANIC|SLAB_ACCOUNT);
827
828 inotify_max_queued_events = 16384;
829 init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
830 init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192;
831
832 return 0;
833}
834fs_initcall(inotify_user_setup);