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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/fanotify.h>
3#include <linux/fcntl.h>
4#include <linux/file.h>
5#include <linux/fs.h>
6#include <linux/anon_inodes.h>
7#include <linux/fsnotify_backend.h>
8#include <linux/init.h>
9#include <linux/mount.h>
10#include <linux/namei.h>
11#include <linux/poll.h>
12#include <linux/security.h>
13#include <linux/syscalls.h>
14#include <linux/slab.h>
15#include <linux/types.h>
16#include <linux/uaccess.h>
17#include <linux/compat.h>
18#include <linux/sched/signal.h>
19
20#include <asm/ioctls.h>
21
22#include "../../mount.h"
23#include "../fdinfo.h"
24#include "fanotify.h"
25
26#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
27#define FANOTIFY_DEFAULT_MAX_MARKS 8192
28#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
29
30/*
31 * All flags that may be specified in parameter event_f_flags of fanotify_init.
32 *
33 * Internal and external open flags are stored together in field f_flags of
34 * struct file. Only external open flags shall be allowed in event_f_flags.
35 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be
36 * excluded.
37 */
38#define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \
39 O_ACCMODE | O_APPEND | O_NONBLOCK | \
40 __O_SYNC | O_DSYNC | O_CLOEXEC | \
41 O_LARGEFILE | O_NOATIME )
42
43extern const struct fsnotify_ops fanotify_fsnotify_ops;
44
45struct kmem_cache *fanotify_mark_cache __read_mostly;
46struct kmem_cache *fanotify_event_cachep __read_mostly;
47struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
48
49/*
50 * Get an fsnotify notification event if one exists and is small
51 * enough to fit in "count". Return an error pointer if the count
52 * is not large enough.
53 *
54 * Called with the group->notification_lock held.
55 */
56static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
57 size_t count)
58{
59 assert_spin_locked(&group->notification_lock);
60
61 pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
62
63 if (fsnotify_notify_queue_is_empty(group))
64 return NULL;
65
66 if (FAN_EVENT_METADATA_LEN > count)
67 return ERR_PTR(-EINVAL);
68
69 /* held the notification_lock the whole time, so this is the
70 * same event we peeked above */
71 return fsnotify_remove_first_event(group);
72}
73
74static int create_fd(struct fsnotify_group *group,
75 struct fanotify_event_info *event,
76 struct file **file)
77{
78 int client_fd;
79 struct file *new_file;
80
81 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
82
83 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
84 if (client_fd < 0)
85 return client_fd;
86
87 /*
88 * we need a new file handle for the userspace program so it can read even if it was
89 * originally opened O_WRONLY.
90 */
91 /* it's possible this event was an overflow event. in that case dentry and mnt
92 * are NULL; That's fine, just don't call dentry open */
93 if (event->path.dentry && event->path.mnt)
94 new_file = dentry_open(&event->path,
95 group->fanotify_data.f_flags | FMODE_NONOTIFY,
96 current_cred());
97 else
98 new_file = ERR_PTR(-EOVERFLOW);
99 if (IS_ERR(new_file)) {
100 /*
101 * we still send an event even if we can't open the file. this
102 * can happen when say tasks are gone and we try to open their
103 * /proc files or we try to open a WRONLY file like in sysfs
104 * we just send the errno to userspace since there isn't much
105 * else we can do.
106 */
107 put_unused_fd(client_fd);
108 client_fd = PTR_ERR(new_file);
109 } else {
110 *file = new_file;
111 }
112
113 return client_fd;
114}
115
116static int fill_event_metadata(struct fsnotify_group *group,
117 struct fanotify_event_metadata *metadata,
118 struct fsnotify_event *fsn_event,
119 struct file **file)
120{
121 int ret = 0;
122 struct fanotify_event_info *event;
123
124 pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
125 group, metadata, fsn_event);
126
127 *file = NULL;
128 event = container_of(fsn_event, struct fanotify_event_info, fse);
129 metadata->event_len = FAN_EVENT_METADATA_LEN;
130 metadata->metadata_len = FAN_EVENT_METADATA_LEN;
131 metadata->vers = FANOTIFY_METADATA_VERSION;
132 metadata->reserved = 0;
133 metadata->mask = fsn_event->mask & FAN_ALL_OUTGOING_EVENTS;
134 metadata->pid = pid_vnr(event->tgid);
135 if (unlikely(fsn_event->mask & FAN_Q_OVERFLOW))
136 metadata->fd = FAN_NOFD;
137 else {
138 metadata->fd = create_fd(group, event, file);
139 if (metadata->fd < 0)
140 ret = metadata->fd;
141 }
142
143 return ret;
144}
145
146static struct fanotify_perm_event_info *dequeue_event(
147 struct fsnotify_group *group, int fd)
148{
149 struct fanotify_perm_event_info *event, *return_e = NULL;
150
151 spin_lock(&group->notification_lock);
152 list_for_each_entry(event, &group->fanotify_data.access_list,
153 fae.fse.list) {
154 if (event->fd != fd)
155 continue;
156
157 list_del_init(&event->fae.fse.list);
158 return_e = event;
159 break;
160 }
161 spin_unlock(&group->notification_lock);
162
163 pr_debug("%s: found return_re=%p\n", __func__, return_e);
164
165 return return_e;
166}
167
168static int process_access_response(struct fsnotify_group *group,
169 struct fanotify_response *response_struct)
170{
171 struct fanotify_perm_event_info *event;
172 int fd = response_struct->fd;
173 int response = response_struct->response;
174
175 pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
176 fd, response);
177 /*
178 * make sure the response is valid, if invalid we do nothing and either
179 * userspace can send a valid response or we will clean it up after the
180 * timeout
181 */
182 switch (response & ~FAN_AUDIT) {
183 case FAN_ALLOW:
184 case FAN_DENY:
185 break;
186 default:
187 return -EINVAL;
188 }
189
190 if (fd < 0)
191 return -EINVAL;
192
193 if ((response & FAN_AUDIT) && !group->fanotify_data.audit)
194 return -EINVAL;
195
196 event = dequeue_event(group, fd);
197 if (!event)
198 return -ENOENT;
199
200 event->response = response;
201 wake_up(&group->fanotify_data.access_waitq);
202
203 return 0;
204}
205
206static ssize_t copy_event_to_user(struct fsnotify_group *group,
207 struct fsnotify_event *event,
208 char __user *buf)
209{
210 struct fanotify_event_metadata fanotify_event_metadata;
211 struct file *f;
212 int fd, ret;
213
214 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
215
216 ret = fill_event_metadata(group, &fanotify_event_metadata, event, &f);
217 if (ret < 0)
218 return ret;
219
220 fd = fanotify_event_metadata.fd;
221 ret = -EFAULT;
222 if (copy_to_user(buf, &fanotify_event_metadata,
223 fanotify_event_metadata.event_len))
224 goto out_close_fd;
225
226 if (fanotify_is_perm_event(event->mask))
227 FANOTIFY_PE(event)->fd = fd;
228
229 if (fd != FAN_NOFD)
230 fd_install(fd, f);
231 return fanotify_event_metadata.event_len;
232
233out_close_fd:
234 if (fd != FAN_NOFD) {
235 put_unused_fd(fd);
236 fput(f);
237 }
238 return ret;
239}
240
241/* intofiy userspace file descriptor functions */
242static __poll_t fanotify_poll(struct file *file, poll_table *wait)
243{
244 struct fsnotify_group *group = file->private_data;
245 __poll_t ret = 0;
246
247 poll_wait(file, &group->notification_waitq, wait);
248 spin_lock(&group->notification_lock);
249 if (!fsnotify_notify_queue_is_empty(group))
250 ret = EPOLLIN | EPOLLRDNORM;
251 spin_unlock(&group->notification_lock);
252
253 return ret;
254}
255
256static ssize_t fanotify_read(struct file *file, char __user *buf,
257 size_t count, loff_t *pos)
258{
259 struct fsnotify_group *group;
260 struct fsnotify_event *kevent;
261 char __user *start;
262 int ret;
263 DEFINE_WAIT_FUNC(wait, woken_wake_function);
264
265 start = buf;
266 group = file->private_data;
267
268 pr_debug("%s: group=%p\n", __func__, group);
269
270 add_wait_queue(&group->notification_waitq, &wait);
271 while (1) {
272 spin_lock(&group->notification_lock);
273 kevent = get_one_event(group, count);
274 spin_unlock(&group->notification_lock);
275
276 if (IS_ERR(kevent)) {
277 ret = PTR_ERR(kevent);
278 break;
279 }
280
281 if (!kevent) {
282 ret = -EAGAIN;
283 if (file->f_flags & O_NONBLOCK)
284 break;
285
286 ret = -ERESTARTSYS;
287 if (signal_pending(current))
288 break;
289
290 if (start != buf)
291 break;
292
293 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
294 continue;
295 }
296
297 ret = copy_event_to_user(group, kevent, buf);
298 if (unlikely(ret == -EOPENSTALE)) {
299 /*
300 * We cannot report events with stale fd so drop it.
301 * Setting ret to 0 will continue the event loop and
302 * do the right thing if there are no more events to
303 * read (i.e. return bytes read, -EAGAIN or wait).
304 */
305 ret = 0;
306 }
307
308 /*
309 * Permission events get queued to wait for response. Other
310 * events can be destroyed now.
311 */
312 if (!fanotify_is_perm_event(kevent->mask)) {
313 fsnotify_destroy_event(group, kevent);
314 } else {
315 if (ret <= 0) {
316 FANOTIFY_PE(kevent)->response = FAN_DENY;
317 wake_up(&group->fanotify_data.access_waitq);
318 } else {
319 spin_lock(&group->notification_lock);
320 list_add_tail(&kevent->list,
321 &group->fanotify_data.access_list);
322 spin_unlock(&group->notification_lock);
323 }
324 }
325 if (ret < 0)
326 break;
327 buf += ret;
328 count -= ret;
329 }
330 remove_wait_queue(&group->notification_waitq, &wait);
331
332 if (start != buf && ret != -EFAULT)
333 ret = buf - start;
334 return ret;
335}
336
337static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
338{
339 struct fanotify_response response = { .fd = -1, .response = -1 };
340 struct fsnotify_group *group;
341 int ret;
342
343 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
344 return -EINVAL;
345
346 group = file->private_data;
347
348 if (count > sizeof(response))
349 count = sizeof(response);
350
351 pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
352
353 if (copy_from_user(&response, buf, count))
354 return -EFAULT;
355
356 ret = process_access_response(group, &response);
357 if (ret < 0)
358 count = ret;
359
360 return count;
361}
362
363static int fanotify_release(struct inode *ignored, struct file *file)
364{
365 struct fsnotify_group *group = file->private_data;
366 struct fanotify_perm_event_info *event, *next;
367 struct fsnotify_event *fsn_event;
368
369 /*
370 * Stop new events from arriving in the notification queue. since
371 * userspace cannot use fanotify fd anymore, no event can enter or
372 * leave access_list by now either.
373 */
374 fsnotify_group_stop_queueing(group);
375
376 /*
377 * Process all permission events on access_list and notification queue
378 * and simulate reply from userspace.
379 */
380 spin_lock(&group->notification_lock);
381 list_for_each_entry_safe(event, next, &group->fanotify_data.access_list,
382 fae.fse.list) {
383 pr_debug("%s: found group=%p event=%p\n", __func__, group,
384 event);
385
386 list_del_init(&event->fae.fse.list);
387 event->response = FAN_ALLOW;
388 }
389
390 /*
391 * Destroy all non-permission events. For permission events just
392 * dequeue them and set the response. They will be freed once the
393 * response is consumed and fanotify_get_response() returns.
394 */
395 while (!fsnotify_notify_queue_is_empty(group)) {
396 fsn_event = fsnotify_remove_first_event(group);
397 if (!(fsn_event->mask & FAN_ALL_PERM_EVENTS)) {
398 spin_unlock(&group->notification_lock);
399 fsnotify_destroy_event(group, fsn_event);
400 spin_lock(&group->notification_lock);
401 } else {
402 FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
403 }
404 }
405 spin_unlock(&group->notification_lock);
406
407 /* Response for all permission events it set, wakeup waiters */
408 wake_up(&group->fanotify_data.access_waitq);
409
410 /* matches the fanotify_init->fsnotify_alloc_group */
411 fsnotify_destroy_group(group);
412
413 return 0;
414}
415
416static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
417{
418 struct fsnotify_group *group;
419 struct fsnotify_event *fsn_event;
420 void __user *p;
421 int ret = -ENOTTY;
422 size_t send_len = 0;
423
424 group = file->private_data;
425
426 p = (void __user *) arg;
427
428 switch (cmd) {
429 case FIONREAD:
430 spin_lock(&group->notification_lock);
431 list_for_each_entry(fsn_event, &group->notification_list, list)
432 send_len += FAN_EVENT_METADATA_LEN;
433 spin_unlock(&group->notification_lock);
434 ret = put_user(send_len, (int __user *) p);
435 break;
436 }
437
438 return ret;
439}
440
441static const struct file_operations fanotify_fops = {
442 .show_fdinfo = fanotify_show_fdinfo,
443 .poll = fanotify_poll,
444 .read = fanotify_read,
445 .write = fanotify_write,
446 .fasync = NULL,
447 .release = fanotify_release,
448 .unlocked_ioctl = fanotify_ioctl,
449 .compat_ioctl = fanotify_ioctl,
450 .llseek = noop_llseek,
451};
452
453static int fanotify_find_path(int dfd, const char __user *filename,
454 struct path *path, unsigned int flags)
455{
456 int ret;
457
458 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
459 dfd, filename, flags);
460
461 if (filename == NULL) {
462 struct fd f = fdget(dfd);
463
464 ret = -EBADF;
465 if (!f.file)
466 goto out;
467
468 ret = -ENOTDIR;
469 if ((flags & FAN_MARK_ONLYDIR) &&
470 !(S_ISDIR(file_inode(f.file)->i_mode))) {
471 fdput(f);
472 goto out;
473 }
474
475 *path = f.file->f_path;
476 path_get(path);
477 fdput(f);
478 } else {
479 unsigned int lookup_flags = 0;
480
481 if (!(flags & FAN_MARK_DONT_FOLLOW))
482 lookup_flags |= LOOKUP_FOLLOW;
483 if (flags & FAN_MARK_ONLYDIR)
484 lookup_flags |= LOOKUP_DIRECTORY;
485
486 ret = user_path_at(dfd, filename, lookup_flags, path);
487 if (ret)
488 goto out;
489 }
490
491 /* you can only watch an inode if you have read permissions on it */
492 ret = inode_permission(path->dentry->d_inode, MAY_READ);
493 if (ret)
494 path_put(path);
495out:
496 return ret;
497}
498
499static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
500 __u32 mask,
501 unsigned int flags,
502 int *destroy)
503{
504 __u32 oldmask = 0;
505
506 spin_lock(&fsn_mark->lock);
507 if (!(flags & FAN_MARK_IGNORED_MASK)) {
508 __u32 tmask = fsn_mark->mask & ~mask;
509
510 if (flags & FAN_MARK_ONDIR)
511 tmask &= ~FAN_ONDIR;
512
513 oldmask = fsn_mark->mask;
514 fsn_mark->mask = tmask;
515 } else {
516 __u32 tmask = fsn_mark->ignored_mask & ~mask;
517 if (flags & FAN_MARK_ONDIR)
518 tmask &= ~FAN_ONDIR;
519 fsn_mark->ignored_mask = tmask;
520 }
521 *destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
522 spin_unlock(&fsn_mark->lock);
523
524 return mask & oldmask;
525}
526
527static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
528 struct vfsmount *mnt, __u32 mask,
529 unsigned int flags)
530{
531 struct fsnotify_mark *fsn_mark = NULL;
532 __u32 removed;
533 int destroy_mark;
534
535 mutex_lock(&group->mark_mutex);
536 fsn_mark = fsnotify_find_mark(&real_mount(mnt)->mnt_fsnotify_marks,
537 group);
538 if (!fsn_mark) {
539 mutex_unlock(&group->mark_mutex);
540 return -ENOENT;
541 }
542
543 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
544 &destroy_mark);
545 if (removed & real_mount(mnt)->mnt_fsnotify_mask)
546 fsnotify_recalc_mask(real_mount(mnt)->mnt_fsnotify_marks);
547 if (destroy_mark)
548 fsnotify_detach_mark(fsn_mark);
549 mutex_unlock(&group->mark_mutex);
550 if (destroy_mark)
551 fsnotify_free_mark(fsn_mark);
552
553 fsnotify_put_mark(fsn_mark);
554 return 0;
555}
556
557static int fanotify_remove_inode_mark(struct fsnotify_group *group,
558 struct inode *inode, __u32 mask,
559 unsigned int flags)
560{
561 struct fsnotify_mark *fsn_mark = NULL;
562 __u32 removed;
563 int destroy_mark;
564
565 mutex_lock(&group->mark_mutex);
566 fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
567 if (!fsn_mark) {
568 mutex_unlock(&group->mark_mutex);
569 return -ENOENT;
570 }
571
572 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
573 &destroy_mark);
574 if (removed & inode->i_fsnotify_mask)
575 fsnotify_recalc_mask(inode->i_fsnotify_marks);
576 if (destroy_mark)
577 fsnotify_detach_mark(fsn_mark);
578 mutex_unlock(&group->mark_mutex);
579 if (destroy_mark)
580 fsnotify_free_mark(fsn_mark);
581
582 /* matches the fsnotify_find_mark() */
583 fsnotify_put_mark(fsn_mark);
584
585 return 0;
586}
587
588static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
589 __u32 mask,
590 unsigned int flags)
591{
592 __u32 oldmask = -1;
593
594 spin_lock(&fsn_mark->lock);
595 if (!(flags & FAN_MARK_IGNORED_MASK)) {
596 __u32 tmask = fsn_mark->mask | mask;
597
598 if (flags & FAN_MARK_ONDIR)
599 tmask |= FAN_ONDIR;
600
601 oldmask = fsn_mark->mask;
602 fsn_mark->mask = tmask;
603 } else {
604 __u32 tmask = fsn_mark->ignored_mask | mask;
605 if (flags & FAN_MARK_ONDIR)
606 tmask |= FAN_ONDIR;
607
608 fsn_mark->ignored_mask = tmask;
609 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
610 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
611 }
612 spin_unlock(&fsn_mark->lock);
613
614 return mask & ~oldmask;
615}
616
617static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
618 struct inode *inode,
619 struct vfsmount *mnt)
620{
621 struct fsnotify_mark *mark;
622 int ret;
623
624 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
625 return ERR_PTR(-ENOSPC);
626
627 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
628 if (!mark)
629 return ERR_PTR(-ENOMEM);
630
631 fsnotify_init_mark(mark, group);
632 ret = fsnotify_add_mark_locked(mark, inode, mnt, 0);
633 if (ret) {
634 fsnotify_put_mark(mark);
635 return ERR_PTR(ret);
636 }
637
638 return mark;
639}
640
641
642static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
643 struct vfsmount *mnt, __u32 mask,
644 unsigned int flags)
645{
646 struct fsnotify_mark *fsn_mark;
647 __u32 added;
648
649 mutex_lock(&group->mark_mutex);
650 fsn_mark = fsnotify_find_mark(&real_mount(mnt)->mnt_fsnotify_marks,
651 group);
652 if (!fsn_mark) {
653 fsn_mark = fanotify_add_new_mark(group, NULL, mnt);
654 if (IS_ERR(fsn_mark)) {
655 mutex_unlock(&group->mark_mutex);
656 return PTR_ERR(fsn_mark);
657 }
658 }
659 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
660 if (added & ~real_mount(mnt)->mnt_fsnotify_mask)
661 fsnotify_recalc_mask(real_mount(mnt)->mnt_fsnotify_marks);
662 mutex_unlock(&group->mark_mutex);
663
664 fsnotify_put_mark(fsn_mark);
665 return 0;
666}
667
668static int fanotify_add_inode_mark(struct fsnotify_group *group,
669 struct inode *inode, __u32 mask,
670 unsigned int flags)
671{
672 struct fsnotify_mark *fsn_mark;
673 __u32 added;
674
675 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
676
677 /*
678 * If some other task has this inode open for write we should not add
679 * an ignored mark, unless that ignored mark is supposed to survive
680 * modification changes anyway.
681 */
682 if ((flags & FAN_MARK_IGNORED_MASK) &&
683 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
684 (atomic_read(&inode->i_writecount) > 0))
685 return 0;
686
687 mutex_lock(&group->mark_mutex);
688 fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group);
689 if (!fsn_mark) {
690 fsn_mark = fanotify_add_new_mark(group, inode, NULL);
691 if (IS_ERR(fsn_mark)) {
692 mutex_unlock(&group->mark_mutex);
693 return PTR_ERR(fsn_mark);
694 }
695 }
696 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
697 if (added & ~inode->i_fsnotify_mask)
698 fsnotify_recalc_mask(inode->i_fsnotify_marks);
699 mutex_unlock(&group->mark_mutex);
700
701 fsnotify_put_mark(fsn_mark);
702 return 0;
703}
704
705/* fanotify syscalls */
706SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
707{
708 struct fsnotify_group *group;
709 int f_flags, fd;
710 struct user_struct *user;
711 struct fanotify_event_info *oevent;
712
713 pr_debug("%s: flags=%d event_f_flags=%d\n",
714 __func__, flags, event_f_flags);
715
716 if (!capable(CAP_SYS_ADMIN))
717 return -EPERM;
718
719#ifdef CONFIG_AUDITSYSCALL
720 if (flags & ~(FAN_ALL_INIT_FLAGS | FAN_ENABLE_AUDIT))
721#else
722 if (flags & ~FAN_ALL_INIT_FLAGS)
723#endif
724 return -EINVAL;
725
726 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
727 return -EINVAL;
728
729 switch (event_f_flags & O_ACCMODE) {
730 case O_RDONLY:
731 case O_RDWR:
732 case O_WRONLY:
733 break;
734 default:
735 return -EINVAL;
736 }
737
738 user = get_current_user();
739 if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
740 free_uid(user);
741 return -EMFILE;
742 }
743
744 f_flags = O_RDWR | FMODE_NONOTIFY;
745 if (flags & FAN_CLOEXEC)
746 f_flags |= O_CLOEXEC;
747 if (flags & FAN_NONBLOCK)
748 f_flags |= O_NONBLOCK;
749
750 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
751 group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
752 if (IS_ERR(group)) {
753 free_uid(user);
754 return PTR_ERR(group);
755 }
756
757 group->fanotify_data.user = user;
758 atomic_inc(&user->fanotify_listeners);
759
760 oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL);
761 if (unlikely(!oevent)) {
762 fd = -ENOMEM;
763 goto out_destroy_group;
764 }
765 group->overflow_event = &oevent->fse;
766
767 if (force_o_largefile())
768 event_f_flags |= O_LARGEFILE;
769 group->fanotify_data.f_flags = event_f_flags;
770 init_waitqueue_head(&group->fanotify_data.access_waitq);
771 INIT_LIST_HEAD(&group->fanotify_data.access_list);
772 switch (flags & FAN_ALL_CLASS_BITS) {
773 case FAN_CLASS_NOTIF:
774 group->priority = FS_PRIO_0;
775 break;
776 case FAN_CLASS_CONTENT:
777 group->priority = FS_PRIO_1;
778 break;
779 case FAN_CLASS_PRE_CONTENT:
780 group->priority = FS_PRIO_2;
781 break;
782 default:
783 fd = -EINVAL;
784 goto out_destroy_group;
785 }
786
787 if (flags & FAN_UNLIMITED_QUEUE) {
788 fd = -EPERM;
789 if (!capable(CAP_SYS_ADMIN))
790 goto out_destroy_group;
791 group->max_events = UINT_MAX;
792 } else {
793 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
794 }
795
796 if (flags & FAN_UNLIMITED_MARKS) {
797 fd = -EPERM;
798 if (!capable(CAP_SYS_ADMIN))
799 goto out_destroy_group;
800 group->fanotify_data.max_marks = UINT_MAX;
801 } else {
802 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
803 }
804
805 if (flags & FAN_ENABLE_AUDIT) {
806 fd = -EPERM;
807 if (!capable(CAP_AUDIT_WRITE))
808 goto out_destroy_group;
809 group->fanotify_data.audit = true;
810 }
811
812 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
813 if (fd < 0)
814 goto out_destroy_group;
815
816 return fd;
817
818out_destroy_group:
819 fsnotify_destroy_group(group);
820 return fd;
821}
822
823static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
824 int dfd, const char __user *pathname)
825{
826 struct inode *inode = NULL;
827 struct vfsmount *mnt = NULL;
828 struct fsnotify_group *group;
829 struct fd f;
830 struct path path;
831 u32 valid_mask = FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD;
832 int ret;
833
834 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
835 __func__, fanotify_fd, flags, dfd, pathname, mask);
836
837 /* we only use the lower 32 bits as of right now. */
838 if (mask & ((__u64)0xffffffff << 32))
839 return -EINVAL;
840
841 if (flags & ~FAN_ALL_MARK_FLAGS)
842 return -EINVAL;
843 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
844 case FAN_MARK_ADD: /* fallthrough */
845 case FAN_MARK_REMOVE:
846 if (!mask)
847 return -EINVAL;
848 break;
849 case FAN_MARK_FLUSH:
850 if (flags & ~(FAN_MARK_MOUNT | FAN_MARK_FLUSH))
851 return -EINVAL;
852 break;
853 default:
854 return -EINVAL;
855 }
856
857 if (mask & FAN_ONDIR) {
858 flags |= FAN_MARK_ONDIR;
859 mask &= ~FAN_ONDIR;
860 }
861
862 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
863 valid_mask |= FAN_ALL_PERM_EVENTS;
864
865 if (mask & ~valid_mask)
866 return -EINVAL;
867
868 f = fdget(fanotify_fd);
869 if (unlikely(!f.file))
870 return -EBADF;
871
872 /* verify that this is indeed an fanotify instance */
873 ret = -EINVAL;
874 if (unlikely(f.file->f_op != &fanotify_fops))
875 goto fput_and_out;
876 group = f.file->private_data;
877
878 /*
879 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not
880 * allowed to set permissions events.
881 */
882 ret = -EINVAL;
883 if (mask & FAN_ALL_PERM_EVENTS &&
884 group->priority == FS_PRIO_0)
885 goto fput_and_out;
886
887 if (flags & FAN_MARK_FLUSH) {
888 ret = 0;
889 if (flags & FAN_MARK_MOUNT)
890 fsnotify_clear_vfsmount_marks_by_group(group);
891 else
892 fsnotify_clear_inode_marks_by_group(group);
893 goto fput_and_out;
894 }
895
896 ret = fanotify_find_path(dfd, pathname, &path, flags);
897 if (ret)
898 goto fput_and_out;
899
900 /* inode held in place by reference to path; group by fget on fd */
901 if (!(flags & FAN_MARK_MOUNT))
902 inode = path.dentry->d_inode;
903 else
904 mnt = path.mnt;
905
906 /* create/update an inode mark */
907 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE)) {
908 case FAN_MARK_ADD:
909 if (flags & FAN_MARK_MOUNT)
910 ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
911 else
912 ret = fanotify_add_inode_mark(group, inode, mask, flags);
913 break;
914 case FAN_MARK_REMOVE:
915 if (flags & FAN_MARK_MOUNT)
916 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
917 else
918 ret = fanotify_remove_inode_mark(group, inode, mask, flags);
919 break;
920 default:
921 ret = -EINVAL;
922 }
923
924 path_put(&path);
925fput_and_out:
926 fdput(f);
927 return ret;
928}
929
930SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
931 __u64, mask, int, dfd,
932 const char __user *, pathname)
933{
934 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
935}
936
937#ifdef CONFIG_COMPAT
938COMPAT_SYSCALL_DEFINE6(fanotify_mark,
939 int, fanotify_fd, unsigned int, flags,
940 __u32, mask0, __u32, mask1, int, dfd,
941 const char __user *, pathname)
942{
943 return do_fanotify_mark(fanotify_fd, flags,
944#ifdef __BIG_ENDIAN
945 ((__u64)mask0 << 32) | mask1,
946#else
947 ((__u64)mask1 << 32) | mask0,
948#endif
949 dfd, pathname);
950}
951#endif
952
953/*
954 * fanotify_user_setup - Our initialization function. Note that we cannot return
955 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
956 * must result in panic().
957 */
958static int __init fanotify_user_setup(void)
959{
960 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
961 fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
962 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
963 fanotify_perm_event_cachep =
964 KMEM_CACHE(fanotify_perm_event_info, SLAB_PANIC);
965 }
966
967 return 0;
968}
969device_initcall(fanotify_user_setup);
1#include <linux/fanotify.h>
2#include <linux/fcntl.h>
3#include <linux/file.h>
4#include <linux/fs.h>
5#include <linux/anon_inodes.h>
6#include <linux/fsnotify_backend.h>
7#include <linux/init.h>
8#include <linux/mount.h>
9#include <linux/namei.h>
10#include <linux/poll.h>
11#include <linux/security.h>
12#include <linux/syscalls.h>
13#include <linux/slab.h>
14#include <linux/types.h>
15#include <linux/uaccess.h>
16
17#include <asm/ioctls.h>
18
19#define FANOTIFY_DEFAULT_MAX_EVENTS 16384
20#define FANOTIFY_DEFAULT_MAX_MARKS 8192
21#define FANOTIFY_DEFAULT_MAX_LISTENERS 128
22
23extern const struct fsnotify_ops fanotify_fsnotify_ops;
24
25static struct kmem_cache *fanotify_mark_cache __read_mostly;
26static struct kmem_cache *fanotify_response_event_cache __read_mostly;
27
28struct fanotify_response_event {
29 struct list_head list;
30 __s32 fd;
31 struct fsnotify_event *event;
32};
33
34/*
35 * Get an fsnotify notification event if one exists and is small
36 * enough to fit in "count". Return an error pointer if the count
37 * is not large enough.
38 *
39 * Called with the group->notification_mutex held.
40 */
41static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
42 size_t count)
43{
44 BUG_ON(!mutex_is_locked(&group->notification_mutex));
45
46 pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
47
48 if (fsnotify_notify_queue_is_empty(group))
49 return NULL;
50
51 if (FAN_EVENT_METADATA_LEN > count)
52 return ERR_PTR(-EINVAL);
53
54 /* held the notification_mutex the whole time, so this is the
55 * same event we peeked above */
56 return fsnotify_remove_notify_event(group);
57}
58
59static int create_fd(struct fsnotify_group *group, struct fsnotify_event *event)
60{
61 int client_fd;
62 struct dentry *dentry;
63 struct vfsmount *mnt;
64 struct file *new_file;
65
66 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
67
68 client_fd = get_unused_fd();
69 if (client_fd < 0)
70 return client_fd;
71
72 if (event->data_type != FSNOTIFY_EVENT_PATH) {
73 WARN_ON(1);
74 put_unused_fd(client_fd);
75 return -EINVAL;
76 }
77
78 /*
79 * we need a new file handle for the userspace program so it can read even if it was
80 * originally opened O_WRONLY.
81 */
82 dentry = dget(event->path.dentry);
83 mnt = mntget(event->path.mnt);
84 /* it's possible this event was an overflow event. in that case dentry and mnt
85 * are NULL; That's fine, just don't call dentry open */
86 if (dentry && mnt)
87 new_file = dentry_open(dentry, mnt,
88 group->fanotify_data.f_flags | FMODE_NONOTIFY,
89 current_cred());
90 else
91 new_file = ERR_PTR(-EOVERFLOW);
92 if (IS_ERR(new_file)) {
93 /*
94 * we still send an event even if we can't open the file. this
95 * can happen when say tasks are gone and we try to open their
96 * /proc files or we try to open a WRONLY file like in sysfs
97 * we just send the errno to userspace since there isn't much
98 * else we can do.
99 */
100 put_unused_fd(client_fd);
101 client_fd = PTR_ERR(new_file);
102 } else {
103 fd_install(client_fd, new_file);
104 }
105
106 return client_fd;
107}
108
109static int fill_event_metadata(struct fsnotify_group *group,
110 struct fanotify_event_metadata *metadata,
111 struct fsnotify_event *event)
112{
113 int ret = 0;
114
115 pr_debug("%s: group=%p metadata=%p event=%p\n", __func__,
116 group, metadata, event);
117
118 metadata->event_len = FAN_EVENT_METADATA_LEN;
119 metadata->metadata_len = FAN_EVENT_METADATA_LEN;
120 metadata->vers = FANOTIFY_METADATA_VERSION;
121 metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS;
122 metadata->pid = pid_vnr(event->tgid);
123 if (unlikely(event->mask & FAN_Q_OVERFLOW))
124 metadata->fd = FAN_NOFD;
125 else {
126 metadata->fd = create_fd(group, event);
127 if (metadata->fd < 0)
128 ret = metadata->fd;
129 }
130
131 return ret;
132}
133
134#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
135static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group,
136 __s32 fd)
137{
138 struct fanotify_response_event *re, *return_re = NULL;
139
140 mutex_lock(&group->fanotify_data.access_mutex);
141 list_for_each_entry(re, &group->fanotify_data.access_list, list) {
142 if (re->fd != fd)
143 continue;
144
145 list_del_init(&re->list);
146 return_re = re;
147 break;
148 }
149 mutex_unlock(&group->fanotify_data.access_mutex);
150
151 pr_debug("%s: found return_re=%p\n", __func__, return_re);
152
153 return return_re;
154}
155
156static int process_access_response(struct fsnotify_group *group,
157 struct fanotify_response *response_struct)
158{
159 struct fanotify_response_event *re;
160 __s32 fd = response_struct->fd;
161 __u32 response = response_struct->response;
162
163 pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group,
164 fd, response);
165 /*
166 * make sure the response is valid, if invalid we do nothing and either
167 * userspace can send a valid response or we will clean it up after the
168 * timeout
169 */
170 switch (response) {
171 case FAN_ALLOW:
172 case FAN_DENY:
173 break;
174 default:
175 return -EINVAL;
176 }
177
178 if (fd < 0)
179 return -EINVAL;
180
181 re = dequeue_re(group, fd);
182 if (!re)
183 return -ENOENT;
184
185 re->event->response = response;
186
187 wake_up(&group->fanotify_data.access_waitq);
188
189 kmem_cache_free(fanotify_response_event_cache, re);
190
191 return 0;
192}
193
194static int prepare_for_access_response(struct fsnotify_group *group,
195 struct fsnotify_event *event,
196 __s32 fd)
197{
198 struct fanotify_response_event *re;
199
200 if (!(event->mask & FAN_ALL_PERM_EVENTS))
201 return 0;
202
203 re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL);
204 if (!re)
205 return -ENOMEM;
206
207 re->event = event;
208 re->fd = fd;
209
210 mutex_lock(&group->fanotify_data.access_mutex);
211
212 if (atomic_read(&group->fanotify_data.bypass_perm)) {
213 mutex_unlock(&group->fanotify_data.access_mutex);
214 kmem_cache_free(fanotify_response_event_cache, re);
215 event->response = FAN_ALLOW;
216 return 0;
217 }
218
219 list_add_tail(&re->list, &group->fanotify_data.access_list);
220 mutex_unlock(&group->fanotify_data.access_mutex);
221
222 return 0;
223}
224
225static void remove_access_response(struct fsnotify_group *group,
226 struct fsnotify_event *event,
227 __s32 fd)
228{
229 struct fanotify_response_event *re;
230
231 if (!(event->mask & FAN_ALL_PERM_EVENTS))
232 return;
233
234 re = dequeue_re(group, fd);
235 if (!re)
236 return;
237
238 BUG_ON(re->event != event);
239
240 kmem_cache_free(fanotify_response_event_cache, re);
241
242 return;
243}
244#else
245static int prepare_for_access_response(struct fsnotify_group *group,
246 struct fsnotify_event *event,
247 __s32 fd)
248{
249 return 0;
250}
251
252static void remove_access_response(struct fsnotify_group *group,
253 struct fsnotify_event *event,
254 __s32 fd)
255{
256 return;
257}
258#endif
259
260static ssize_t copy_event_to_user(struct fsnotify_group *group,
261 struct fsnotify_event *event,
262 char __user *buf)
263{
264 struct fanotify_event_metadata fanotify_event_metadata;
265 int fd, ret;
266
267 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
268
269 ret = fill_event_metadata(group, &fanotify_event_metadata, event);
270 if (ret < 0)
271 goto out;
272
273 fd = fanotify_event_metadata.fd;
274 ret = prepare_for_access_response(group, event, fd);
275 if (ret)
276 goto out_close_fd;
277
278 ret = -EFAULT;
279 if (copy_to_user(buf, &fanotify_event_metadata,
280 fanotify_event_metadata.event_len))
281 goto out_kill_access_response;
282
283 return fanotify_event_metadata.event_len;
284
285out_kill_access_response:
286 remove_access_response(group, event, fd);
287out_close_fd:
288 if (fd != FAN_NOFD)
289 sys_close(fd);
290out:
291#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
292 if (event->mask & FAN_ALL_PERM_EVENTS) {
293 event->response = FAN_DENY;
294 wake_up(&group->fanotify_data.access_waitq);
295 }
296#endif
297 return ret;
298}
299
300/* intofiy userspace file descriptor functions */
301static unsigned int fanotify_poll(struct file *file, poll_table *wait)
302{
303 struct fsnotify_group *group = file->private_data;
304 int ret = 0;
305
306 poll_wait(file, &group->notification_waitq, wait);
307 mutex_lock(&group->notification_mutex);
308 if (!fsnotify_notify_queue_is_empty(group))
309 ret = POLLIN | POLLRDNORM;
310 mutex_unlock(&group->notification_mutex);
311
312 return ret;
313}
314
315static ssize_t fanotify_read(struct file *file, char __user *buf,
316 size_t count, loff_t *pos)
317{
318 struct fsnotify_group *group;
319 struct fsnotify_event *kevent;
320 char __user *start;
321 int ret;
322 DEFINE_WAIT(wait);
323
324 start = buf;
325 group = file->private_data;
326
327 pr_debug("%s: group=%p\n", __func__, group);
328
329 while (1) {
330 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE);
331
332 mutex_lock(&group->notification_mutex);
333 kevent = get_one_event(group, count);
334 mutex_unlock(&group->notification_mutex);
335
336 if (kevent) {
337 ret = PTR_ERR(kevent);
338 if (IS_ERR(kevent))
339 break;
340 ret = copy_event_to_user(group, kevent, buf);
341 fsnotify_put_event(kevent);
342 if (ret < 0)
343 break;
344 buf += ret;
345 count -= ret;
346 continue;
347 }
348
349 ret = -EAGAIN;
350 if (file->f_flags & O_NONBLOCK)
351 break;
352 ret = -ERESTARTSYS;
353 if (signal_pending(current))
354 break;
355
356 if (start != buf)
357 break;
358
359 schedule();
360 }
361
362 finish_wait(&group->notification_waitq, &wait);
363 if (start != buf && ret != -EFAULT)
364 ret = buf - start;
365 return ret;
366}
367
368static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
369{
370#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
371 struct fanotify_response response = { .fd = -1, .response = -1 };
372 struct fsnotify_group *group;
373 int ret;
374
375 group = file->private_data;
376
377 if (count > sizeof(response))
378 count = sizeof(response);
379
380 pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
381
382 if (copy_from_user(&response, buf, count))
383 return -EFAULT;
384
385 ret = process_access_response(group, &response);
386 if (ret < 0)
387 count = ret;
388
389 return count;
390#else
391 return -EINVAL;
392#endif
393}
394
395static int fanotify_release(struct inode *ignored, struct file *file)
396{
397 struct fsnotify_group *group = file->private_data;
398
399#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
400 struct fanotify_response_event *re, *lre;
401
402 mutex_lock(&group->fanotify_data.access_mutex);
403
404 atomic_inc(&group->fanotify_data.bypass_perm);
405
406 list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) {
407 pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group,
408 re, re->event);
409
410 list_del_init(&re->list);
411 re->event->response = FAN_ALLOW;
412
413 kmem_cache_free(fanotify_response_event_cache, re);
414 }
415 mutex_unlock(&group->fanotify_data.access_mutex);
416
417 wake_up(&group->fanotify_data.access_waitq);
418#endif
419 /* matches the fanotify_init->fsnotify_alloc_group */
420 fsnotify_put_group(group);
421
422 return 0;
423}
424
425static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
426{
427 struct fsnotify_group *group;
428 struct fsnotify_event_holder *holder;
429 void __user *p;
430 int ret = -ENOTTY;
431 size_t send_len = 0;
432
433 group = file->private_data;
434
435 p = (void __user *) arg;
436
437 switch (cmd) {
438 case FIONREAD:
439 mutex_lock(&group->notification_mutex);
440 list_for_each_entry(holder, &group->notification_list, event_list)
441 send_len += FAN_EVENT_METADATA_LEN;
442 mutex_unlock(&group->notification_mutex);
443 ret = put_user(send_len, (int __user *) p);
444 break;
445 }
446
447 return ret;
448}
449
450static const struct file_operations fanotify_fops = {
451 .poll = fanotify_poll,
452 .read = fanotify_read,
453 .write = fanotify_write,
454 .fasync = NULL,
455 .release = fanotify_release,
456 .unlocked_ioctl = fanotify_ioctl,
457 .compat_ioctl = fanotify_ioctl,
458 .llseek = noop_llseek,
459};
460
461static void fanotify_free_mark(struct fsnotify_mark *fsn_mark)
462{
463 kmem_cache_free(fanotify_mark_cache, fsn_mark);
464}
465
466static int fanotify_find_path(int dfd, const char __user *filename,
467 struct path *path, unsigned int flags)
468{
469 int ret;
470
471 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
472 dfd, filename, flags);
473
474 if (filename == NULL) {
475 struct file *file;
476 int fput_needed;
477
478 ret = -EBADF;
479 file = fget_light(dfd, &fput_needed);
480 if (!file)
481 goto out;
482
483 ret = -ENOTDIR;
484 if ((flags & FAN_MARK_ONLYDIR) &&
485 !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) {
486 fput_light(file, fput_needed);
487 goto out;
488 }
489
490 *path = file->f_path;
491 path_get(path);
492 fput_light(file, fput_needed);
493 } else {
494 unsigned int lookup_flags = 0;
495
496 if (!(flags & FAN_MARK_DONT_FOLLOW))
497 lookup_flags |= LOOKUP_FOLLOW;
498 if (flags & FAN_MARK_ONLYDIR)
499 lookup_flags |= LOOKUP_DIRECTORY;
500
501 ret = user_path_at(dfd, filename, lookup_flags, path);
502 if (ret)
503 goto out;
504 }
505
506 /* you can only watch an inode if you have read permissions on it */
507 ret = inode_permission(path->dentry->d_inode, MAY_READ);
508 if (ret)
509 path_put(path);
510out:
511 return ret;
512}
513
514static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
515 __u32 mask,
516 unsigned int flags)
517{
518 __u32 oldmask;
519
520 spin_lock(&fsn_mark->lock);
521 if (!(flags & FAN_MARK_IGNORED_MASK)) {
522 oldmask = fsn_mark->mask;
523 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
524 } else {
525 oldmask = fsn_mark->ignored_mask;
526 fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
527 }
528 spin_unlock(&fsn_mark->lock);
529
530 if (!(oldmask & ~mask))
531 fsnotify_destroy_mark(fsn_mark);
532
533 return mask & oldmask;
534}
535
536static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
537 struct vfsmount *mnt, __u32 mask,
538 unsigned int flags)
539{
540 struct fsnotify_mark *fsn_mark = NULL;
541 __u32 removed;
542
543 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
544 if (!fsn_mark)
545 return -ENOENT;
546
547 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
548 fsnotify_put_mark(fsn_mark);
549 if (removed & mnt->mnt_fsnotify_mask)
550 fsnotify_recalc_vfsmount_mask(mnt);
551
552 return 0;
553}
554
555static int fanotify_remove_inode_mark(struct fsnotify_group *group,
556 struct inode *inode, __u32 mask,
557 unsigned int flags)
558{
559 struct fsnotify_mark *fsn_mark = NULL;
560 __u32 removed;
561
562 fsn_mark = fsnotify_find_inode_mark(group, inode);
563 if (!fsn_mark)
564 return -ENOENT;
565
566 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags);
567 /* matches the fsnotify_find_inode_mark() */
568 fsnotify_put_mark(fsn_mark);
569 if (removed & inode->i_fsnotify_mask)
570 fsnotify_recalc_inode_mask(inode);
571
572 return 0;
573}
574
575static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
576 __u32 mask,
577 unsigned int flags)
578{
579 __u32 oldmask = -1;
580
581 spin_lock(&fsn_mark->lock);
582 if (!(flags & FAN_MARK_IGNORED_MASK)) {
583 oldmask = fsn_mark->mask;
584 fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
585 } else {
586 __u32 tmask = fsn_mark->ignored_mask | mask;
587 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
588 if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
589 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
590 }
591
592 if (!(flags & FAN_MARK_ONDIR)) {
593 __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
594 fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
595 }
596
597 spin_unlock(&fsn_mark->lock);
598
599 return mask & ~oldmask;
600}
601
602static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
603 struct vfsmount *mnt, __u32 mask,
604 unsigned int flags)
605{
606 struct fsnotify_mark *fsn_mark;
607 __u32 added;
608 int ret = 0;
609
610 fsn_mark = fsnotify_find_vfsmount_mark(group, mnt);
611 if (!fsn_mark) {
612 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
613 return -ENOSPC;
614
615 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
616 if (!fsn_mark)
617 return -ENOMEM;
618
619 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
620 ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0);
621 if (ret)
622 goto err;
623 }
624 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
625
626 if (added & ~mnt->mnt_fsnotify_mask)
627 fsnotify_recalc_vfsmount_mask(mnt);
628err:
629 fsnotify_put_mark(fsn_mark);
630 return ret;
631}
632
633static int fanotify_add_inode_mark(struct fsnotify_group *group,
634 struct inode *inode, __u32 mask,
635 unsigned int flags)
636{
637 struct fsnotify_mark *fsn_mark;
638 __u32 added;
639 int ret = 0;
640
641 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
642
643 /*
644 * If some other task has this inode open for write we should not add
645 * an ignored mark, unless that ignored mark is supposed to survive
646 * modification changes anyway.
647 */
648 if ((flags & FAN_MARK_IGNORED_MASK) &&
649 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
650 (atomic_read(&inode->i_writecount) > 0))
651 return 0;
652
653 fsn_mark = fsnotify_find_inode_mark(group, inode);
654 if (!fsn_mark) {
655 if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks)
656 return -ENOSPC;
657
658 fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
659 if (!fsn_mark)
660 return -ENOMEM;
661
662 fsnotify_init_mark(fsn_mark, fanotify_free_mark);
663 ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0);
664 if (ret)
665 goto err;
666 }
667 added = fanotify_mark_add_to_mask(fsn_mark, mask, flags);
668
669 if (added & ~inode->i_fsnotify_mask)
670 fsnotify_recalc_inode_mask(inode);
671err:
672 fsnotify_put_mark(fsn_mark);
673 return ret;
674}
675
676/* fanotify syscalls */
677SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
678{
679 struct fsnotify_group *group;
680 int f_flags, fd;
681 struct user_struct *user;
682
683 pr_debug("%s: flags=%d event_f_flags=%d\n",
684 __func__, flags, event_f_flags);
685
686 if (!capable(CAP_SYS_ADMIN))
687 return -EPERM;
688
689 if (flags & ~FAN_ALL_INIT_FLAGS)
690 return -EINVAL;
691
692 user = get_current_user();
693 if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {
694 free_uid(user);
695 return -EMFILE;
696 }
697
698 f_flags = O_RDWR | FMODE_NONOTIFY;
699 if (flags & FAN_CLOEXEC)
700 f_flags |= O_CLOEXEC;
701 if (flags & FAN_NONBLOCK)
702 f_flags |= O_NONBLOCK;
703
704 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
705 group = fsnotify_alloc_group(&fanotify_fsnotify_ops);
706 if (IS_ERR(group)) {
707 free_uid(user);
708 return PTR_ERR(group);
709 }
710
711 group->fanotify_data.user = user;
712 atomic_inc(&user->fanotify_listeners);
713
714 group->fanotify_data.f_flags = event_f_flags;
715#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
716 mutex_init(&group->fanotify_data.access_mutex);
717 init_waitqueue_head(&group->fanotify_data.access_waitq);
718 INIT_LIST_HEAD(&group->fanotify_data.access_list);
719 atomic_set(&group->fanotify_data.bypass_perm, 0);
720#endif
721 switch (flags & FAN_ALL_CLASS_BITS) {
722 case FAN_CLASS_NOTIF:
723 group->priority = FS_PRIO_0;
724 break;
725 case FAN_CLASS_CONTENT:
726 group->priority = FS_PRIO_1;
727 break;
728 case FAN_CLASS_PRE_CONTENT:
729 group->priority = FS_PRIO_2;
730 break;
731 default:
732 fd = -EINVAL;
733 goto out_put_group;
734 }
735
736 if (flags & FAN_UNLIMITED_QUEUE) {
737 fd = -EPERM;
738 if (!capable(CAP_SYS_ADMIN))
739 goto out_put_group;
740 group->max_events = UINT_MAX;
741 } else {
742 group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS;
743 }
744
745 if (flags & FAN_UNLIMITED_MARKS) {
746 fd = -EPERM;
747 if (!capable(CAP_SYS_ADMIN))
748 goto out_put_group;
749 group->fanotify_data.max_marks = UINT_MAX;
750 } else {
751 group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS;
752 }
753
754 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
755 if (fd < 0)
756 goto out_put_group;
757
758 return fd;
759
760out_put_group:
761 fsnotify_put_group(group);
762 return fd;
763}
764
765SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags,
766 __u64 mask, int dfd,
767 const char __user * pathname)
768{
769 struct inode *inode = NULL;
770 struct vfsmount *mnt = NULL;
771 struct fsnotify_group *group;
772 struct file *filp;
773 struct path path;
774 int ret, fput_needed;
775
776 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
777 __func__, fanotify_fd, flags, dfd, pathname, mask);
778
779 /* we only use the lower 32 bits as of right now. */
780 if (mask & ((__u64)0xffffffff << 32))
781 return -EINVAL;
782
783 if (flags & ~FAN_ALL_MARK_FLAGS)
784 return -EINVAL;
785 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
786 case FAN_MARK_ADD: /* fallthrough */
787 case FAN_MARK_REMOVE:
788 if (!mask)
789 return -EINVAL;
790 case FAN_MARK_FLUSH:
791 break;
792 default:
793 return -EINVAL;
794 }
795
796 if (mask & FAN_ONDIR) {
797 flags |= FAN_MARK_ONDIR;
798 mask &= ~FAN_ONDIR;
799 }
800
801#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
802 if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD))
803#else
804 if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD))
805#endif
806 return -EINVAL;
807
808 filp = fget_light(fanotify_fd, &fput_needed);
809 if (unlikely(!filp))
810 return -EBADF;
811
812 /* verify that this is indeed an fanotify instance */
813 ret = -EINVAL;
814 if (unlikely(filp->f_op != &fanotify_fops))
815 goto fput_and_out;
816 group = filp->private_data;
817
818 /*
819 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not
820 * allowed to set permissions events.
821 */
822 ret = -EINVAL;
823 if (mask & FAN_ALL_PERM_EVENTS &&
824 group->priority == FS_PRIO_0)
825 goto fput_and_out;
826
827 ret = fanotify_find_path(dfd, pathname, &path, flags);
828 if (ret)
829 goto fput_and_out;
830
831 /* inode held in place by reference to path; group by fget on fd */
832 if (!(flags & FAN_MARK_MOUNT))
833 inode = path.dentry->d_inode;
834 else
835 mnt = path.mnt;
836
837 /* create/update an inode mark */
838 switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) {
839 case FAN_MARK_ADD:
840 if (flags & FAN_MARK_MOUNT)
841 ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags);
842 else
843 ret = fanotify_add_inode_mark(group, inode, mask, flags);
844 break;
845 case FAN_MARK_REMOVE:
846 if (flags & FAN_MARK_MOUNT)
847 ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags);
848 else
849 ret = fanotify_remove_inode_mark(group, inode, mask, flags);
850 break;
851 case FAN_MARK_FLUSH:
852 if (flags & FAN_MARK_MOUNT)
853 fsnotify_clear_vfsmount_marks_by_group(group);
854 else
855 fsnotify_clear_inode_marks_by_group(group);
856 break;
857 default:
858 ret = -EINVAL;
859 }
860
861 path_put(&path);
862fput_and_out:
863 fput_light(filp, fput_needed);
864 return ret;
865}
866
867#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
868asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask,
869 long dfd, long pathname)
870{
871 return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags,
872 mask, (int) dfd,
873 (const char __user *) pathname);
874}
875SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark);
876#endif
877
878/*
879 * fanotify_user_setup - Our initialization function. Note that we cannot return
880 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
881 * must result in panic().
882 */
883static int __init fanotify_user_setup(void)
884{
885 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
886 fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event,
887 SLAB_PANIC);
888
889 return 0;
890}
891device_initcall(fanotify_user_setup);