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22#include <linux/kernel.h>
23#include <linux/sched.h>
24#include <linux/slab.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/mount.h>
28#include <linux/namei.h>
29#include <linux/poll.h>
30#include <linux/init.h>
31#include <linux/list.h>
32#include <linux/inotify.h>
33#include <linux/syscalls.h>
34#include <linux/magic.h>
35
36#include <asm/ioctls.h>
37
38static struct kmem_cache *watch_cachep __read_mostly;
39static struct kmem_cache *event_cachep __read_mostly;
40
41static struct vfsmount *inotify_mnt __read_mostly;
42
43
44static int inotify_max_user_instances __read_mostly;
45static int inotify_max_user_watches __read_mostly;
46static int inotify_max_queued_events __read_mostly;
47
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73
74struct inotify_device {
75 wait_queue_head_t wq;
76 struct mutex ev_mutex;
77 struct mutex up_mutex;
78 struct list_head events;
79 atomic_t count;
80 struct user_struct *user;
81 struct inotify_handle *ih;
82 struct fasync_struct *fa;
83 unsigned int queue_size;
84 unsigned int event_count;
85 unsigned int max_events;
86};
87
88
89
90
91
92
93
94
95
96struct inotify_kernel_event {
97 struct inotify_event event;
98 struct list_head list;
99 char *name;
100};
101
102
103
104
105
106struct inotify_user_watch {
107 struct inotify_device *dev;
108 struct inotify_watch wdata;
109};
110
111#ifdef CONFIG_SYSCTL
112
113#include <linux/sysctl.h>
114
115static int zero;
116
117ctl_table inotify_table[] = {
118 {
119 .ctl_name = INOTIFY_MAX_USER_INSTANCES,
120 .procname = "max_user_instances",
121 .data = &inotify_max_user_instances,
122 .maxlen = sizeof(int),
123 .mode = 0644,
124 .proc_handler = &proc_dointvec_minmax,
125 .strategy = &sysctl_intvec,
126 .extra1 = &zero,
127 },
128 {
129 .ctl_name = INOTIFY_MAX_USER_WATCHES,
130 .procname = "max_user_watches",
131 .data = &inotify_max_user_watches,
132 .maxlen = sizeof(int),
133 .mode = 0644,
134 .proc_handler = &proc_dointvec_minmax,
135 .strategy = &sysctl_intvec,
136 .extra1 = &zero,
137 },
138 {
139 .ctl_name = INOTIFY_MAX_QUEUED_EVENTS,
140 .procname = "max_queued_events",
141 .data = &inotify_max_queued_events,
142 .maxlen = sizeof(int),
143 .mode = 0644,
144 .proc_handler = &proc_dointvec_minmax,
145 .strategy = &sysctl_intvec,
146 .extra1 = &zero
147 },
148 { .ctl_name = 0 }
149};
150#endif
151
152static inline void get_inotify_dev(struct inotify_device *dev)
153{
154 atomic_inc(&dev->count);
155}
156
157static inline void put_inotify_dev(struct inotify_device *dev)
158{
159 if (atomic_dec_and_test(&dev->count)) {
160 atomic_dec(&dev->user->inotify_devs);
161 free_uid(dev->user);
162 kfree(dev);
163 }
164}
165
166
167
168
169static void free_inotify_user_watch(struct inotify_watch *w)
170{
171 struct inotify_user_watch *watch;
172 struct inotify_device *dev;
173
174 watch = container_of(w, struct inotify_user_watch, wdata);
175 dev = watch->dev;
176
177 atomic_dec(&dev->user->inotify_watches);
178 put_inotify_dev(dev);
179 kmem_cache_free(watch_cachep, watch);
180}
181
182
183
184
185
186
187static struct inotify_kernel_event * kernel_event(s32 wd, u32 mask, u32 cookie,
188 const char *name)
189{
190 struct inotify_kernel_event *kevent;
191
192 kevent = kmem_cache_alloc(event_cachep, GFP_NOFS);
193 if (unlikely(!kevent))
194 return NULL;
195
196
197 memset(&kevent->event, 0, sizeof(struct inotify_event));
198
199 kevent->event.wd = wd;
200 kevent->event.mask = mask;
201 kevent->event.cookie = cookie;
202
203 INIT_LIST_HEAD(&kevent->list);
204
205 if (name) {
206 size_t len, rem, event_size = sizeof(struct inotify_event);
207
208
209
210
211
212
213
214
215 len = strlen(name) + 1;
216 rem = event_size - len;
217 if (len > event_size) {
218 rem = event_size - (len % event_size);
219 if (len % event_size == 0)
220 rem = 0;
221 }
222
223 kevent->name = kmalloc(len + rem, GFP_KERNEL);
224 if (unlikely(!kevent->name)) {
225 kmem_cache_free(event_cachep, kevent);
226 return NULL;
227 }
228 memcpy(kevent->name, name, len);
229 if (rem)
230 memset(kevent->name + len, 0, rem);
231 kevent->event.len = len + rem;
232 } else {
233 kevent->event.len = 0;
234 kevent->name = NULL;
235 }
236
237 return kevent;
238}
239
240
241
242
243
244
245static inline struct inotify_kernel_event *
246inotify_dev_get_event(struct inotify_device *dev)
247{
248 return list_entry(dev->events.next, struct inotify_kernel_event, list);
249}
250
251
252
253
254
255
256static inline struct inotify_kernel_event *
257inotify_dev_get_last_event(struct inotify_device *dev)
258{
259 if (list_empty(&dev->events))
260 return NULL;
261 return list_entry(dev->events.prev, struct inotify_kernel_event, list);
262}
263
264
265
266
267
268
269
270static void inotify_dev_queue_event(struct inotify_watch *w, u32 wd, u32 mask,
271 u32 cookie, const char *name,
272 struct inode *ignored)
273{
274 struct inotify_user_watch *watch;
275 struct inotify_device *dev;
276 struct inotify_kernel_event *kevent, *last;
277
278 watch = container_of(w, struct inotify_user_watch, wdata);
279 dev = watch->dev;
280
281 mutex_lock(&dev->ev_mutex);
282
283
284
285
286 if (mask & IN_IGNORED || w->mask & IN_ONESHOT)
287 put_inotify_watch(w);
288
289
290 last = inotify_dev_get_last_event(dev);
291 if (last && last->event.mask == mask && last->event.wd == wd &&
292 last->event.cookie == cookie) {
293 const char *lastname = last->name;
294
295 if (!name && !lastname)
296 goto out;
297 if (name && lastname && !strcmp(lastname, name))
298 goto out;
299 }
300
301
302 if (unlikely(dev->event_count > dev->max_events))
303 goto out;
304
305
306 if (unlikely(dev->event_count == dev->max_events))
307 kevent = kernel_event(-1, IN_Q_OVERFLOW, cookie, NULL);
308 else
309 kevent = kernel_event(wd, mask, cookie, name);
310
311 if (unlikely(!kevent))
312 goto out;
313
314
315 dev->event_count++;
316 dev->queue_size += sizeof(struct inotify_event) + kevent->event.len;
317 list_add_tail(&kevent->list, &dev->events);
318 wake_up_interruptible(&dev->wq);
319 kill_fasync(&dev->fa, SIGIO, POLL_IN);
320
321out:
322 mutex_unlock(&dev->ev_mutex);
323}
324
325
326
327
328
329
330static void remove_kevent(struct inotify_device *dev,
331 struct inotify_kernel_event *kevent)
332{
333 list_del(&kevent->list);
334
335 dev->event_count--;
336 dev->queue_size -= sizeof(struct inotify_event) + kevent->event.len;
337}
338
339
340
341
342static void free_kevent(struct inotify_kernel_event *kevent)
343{
344 kfree(kevent->name);
345 kmem_cache_free(event_cachep, kevent);
346}
347
348
349
350
351
352
353static void inotify_dev_event_dequeue(struct inotify_device *dev)
354{
355 if (!list_empty(&dev->events)) {
356 struct inotify_kernel_event *kevent;
357 kevent = inotify_dev_get_event(dev);
358 remove_kevent(dev, kevent);
359 free_kevent(kevent);
360 }
361}
362
363
364
365
366static int find_inode(const char __user *dirname, struct path *path,
367 unsigned flags)
368{
369 int error;
370
371 error = user_path_at(AT_FDCWD, dirname, flags, path);
372 if (error)
373 return error;
374
375 error = inode_permission(path->dentry->d_inode, MAY_READ);
376 if (error)
377 path_put(path);
378 return error;
379}
380
381
382
383
384
385
386static int create_watch(struct inotify_device *dev, struct inode *inode,
387 u32 mask)
388{
389 struct inotify_user_watch *watch;
390 int ret;
391
392 if (atomic_read(&dev->user->inotify_watches) >=
393 inotify_max_user_watches)
394 return -ENOSPC;
395
396 watch = kmem_cache_alloc(watch_cachep, GFP_KERNEL);
397 if (unlikely(!watch))
398 return -ENOMEM;
399
400
401 get_inotify_dev(dev);
402 watch->dev = dev;
403
404 atomic_inc(&dev->user->inotify_watches);
405
406 inotify_init_watch(&watch->wdata);
407 ret = inotify_add_watch(dev->ih, &watch->wdata, inode, mask);
408 if (ret < 0)
409 free_inotify_user_watch(&watch->wdata);
410
411 return ret;
412}
413
414
415
416static unsigned int inotify_poll(struct file *file, poll_table *wait)
417{
418 struct inotify_device *dev = file->private_data;
419 int ret = 0;
420
421 poll_wait(file, &dev->wq, wait);
422 mutex_lock(&dev->ev_mutex);
423 if (!list_empty(&dev->events))
424 ret = POLLIN | POLLRDNORM;
425 mutex_unlock(&dev->ev_mutex);
426
427 return ret;
428}
429
430static ssize_t inotify_read(struct file *file, char __user *buf,
431 size_t count, loff_t *pos)
432{
433 size_t event_size = sizeof (struct inotify_event);
434 struct inotify_device *dev;
435 char __user *start;
436 int ret;
437 DEFINE_WAIT(wait);
438
439 start = buf;
440 dev = file->private_data;
441
442 while (1) {
443
444 prepare_to_wait(&dev->wq, &wait, TASK_INTERRUPTIBLE);
445
446 mutex_lock(&dev->ev_mutex);
447 if (!list_empty(&dev->events)) {
448 ret = 0;
449 break;
450 }
451 mutex_unlock(&dev->ev_mutex);
452
453 if (file->f_flags & O_NONBLOCK) {
454 ret = -EAGAIN;
455 break;
456 }
457
458 if (signal_pending(current)) {
459 ret = -EINTR;
460 break;
461 }
462
463 schedule();
464 }
465
466 finish_wait(&dev->wq, &wait);
467 if (ret)
468 return ret;
469
470 while (1) {
471 struct inotify_kernel_event *kevent;
472
473 ret = buf - start;
474 if (list_empty(&dev->events))
475 break;
476
477 kevent = inotify_dev_get_event(dev);
478 if (event_size + kevent->event.len > count) {
479 if (ret == 0 && count > 0) {
480
481
482
483
484 ret = -EINVAL;
485 }
486 break;
487 }
488 remove_kevent(dev, kevent);
489
490
491
492
493
494 mutex_unlock(&dev->ev_mutex);
495
496 if (copy_to_user(buf, &kevent->event, event_size)) {
497 ret = -EFAULT;
498 break;
499 }
500 buf += event_size;
501 count -= event_size;
502
503 if (kevent->name) {
504 if (copy_to_user(buf, kevent->name, kevent->event.len)){
505 ret = -EFAULT;
506 break;
507 }
508 buf += kevent->event.len;
509 count -= kevent->event.len;
510 }
511
512 free_kevent(kevent);
513
514 mutex_lock(&dev->ev_mutex);
515 }
516 mutex_unlock(&dev->ev_mutex);
517
518 return ret;
519}
520
521static int inotify_fasync(int fd, struct file *file, int on)
522{
523 struct inotify_device *dev = file->private_data;
524
525 return fasync_helper(fd, file, on, &dev->fa) >= 0 ? 0 : -EIO;
526}
527
528static int inotify_release(struct inode *ignored, struct file *file)
529{
530 struct inotify_device *dev = file->private_data;
531
532 inotify_destroy(dev->ih);
533
534
535 mutex_lock(&dev->ev_mutex);
536 while (!list_empty(&dev->events))
537 inotify_dev_event_dequeue(dev);
538 mutex_unlock(&dev->ev_mutex);
539
540
541 put_inotify_dev(dev);
542
543 return 0;
544}
545
546static long inotify_ioctl(struct file *file, unsigned int cmd,
547 unsigned long arg)
548{
549 struct inotify_device *dev;
550 void __user *p;
551 int ret = -ENOTTY;
552
553 dev = file->private_data;
554 p = (void __user *) arg;
555
556 switch (cmd) {
557 case FIONREAD:
558 ret = put_user(dev->queue_size, (int __user *) p);
559 break;
560 }
561
562 return ret;
563}
564
565static const struct file_operations inotify_fops = {
566 .poll = inotify_poll,
567 .read = inotify_read,
568 .fasync = inotify_fasync,
569 .release = inotify_release,
570 .unlocked_ioctl = inotify_ioctl,
571 .compat_ioctl = inotify_ioctl,
572};
573
574static const struct inotify_operations inotify_user_ops = {
575 .handle_event = inotify_dev_queue_event,
576 .destroy_watch = free_inotify_user_watch,
577};
578
579asmlinkage long sys_inotify_init1(int flags)
580{
581 struct inotify_device *dev;
582 struct inotify_handle *ih;
583 struct user_struct *user;
584 struct file *filp;
585 int fd, ret;
586
587
588 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC);
589 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK);
590
591 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK))
592 return -EINVAL;
593
594 fd = get_unused_fd_flags(flags & O_CLOEXEC);
595 if (fd < 0)
596 return fd;
597
598 filp = get_empty_filp();
599 if (!filp) {
600 ret = -ENFILE;
601 goto out_put_fd;
602 }
603
604 user = get_uid(current->user);
605 if (unlikely(atomic_read(&user->inotify_devs) >=
606 inotify_max_user_instances)) {
607 ret = -EMFILE;
608 goto out_free_uid;
609 }
610
611 dev = kmalloc(sizeof(struct inotify_device), GFP_KERNEL);
612 if (unlikely(!dev)) {
613 ret = -ENOMEM;
614 goto out_free_uid;
615 }
616
617 ih = inotify_init(&inotify_user_ops);
618 if (IS_ERR(ih)) {
619 ret = PTR_ERR(ih);
620 goto out_free_dev;
621 }
622 dev->ih = ih;
623 dev->fa = NULL;
624
625 filp->f_op = &inotify_fops;
626 filp->f_path.mnt = mntget(inotify_mnt);
627 filp->f_path.dentry = dget(inotify_mnt->mnt_root);
628 filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping;
629 filp->f_mode = FMODE_READ;
630 filp->f_flags = O_RDONLY | (flags & O_NONBLOCK);
631 filp->private_data = dev;
632
633 INIT_LIST_HEAD(&dev->events);
634 init_waitqueue_head(&dev->wq);
635 mutex_init(&dev->ev_mutex);
636 mutex_init(&dev->up_mutex);
637 dev->event_count = 0;
638 dev->queue_size = 0;
639 dev->max_events = inotify_max_queued_events;
640 dev->user = user;
641 atomic_set(&dev->count, 0);
642
643 get_inotify_dev(dev);
644 atomic_inc(&user->inotify_devs);
645 fd_install(fd, filp);
646
647 return fd;
648out_free_dev:
649 kfree(dev);
650out_free_uid:
651 free_uid(user);
652 put_filp(filp);
653out_put_fd:
654 put_unused_fd(fd);
655 return ret;
656}
657
658asmlinkage long sys_inotify_init(void)
659{
660 return sys_inotify_init1(0);
661}
662
663asmlinkage long sys_inotify_add_watch(int fd, const char __user *pathname, u32 mask)
664{
665 struct inode *inode;
666 struct inotify_device *dev;
667 struct path path;
668 struct file *filp;
669 int ret, fput_needed;
670 unsigned flags = 0;
671
672 filp = fget_light(fd, &fput_needed);
673 if (unlikely(!filp))
674 return -EBADF;
675
676
677 if (unlikely(filp->f_op != &inotify_fops)) {
678 ret = -EINVAL;
679 goto fput_and_out;
680 }
681
682 if (!(mask & IN_DONT_FOLLOW))
683 flags |= LOOKUP_FOLLOW;
684 if (mask & IN_ONLYDIR)
685 flags |= LOOKUP_DIRECTORY;
686
687 ret = find_inode(pathname, &path, flags);
688 if (unlikely(ret))
689 goto fput_and_out;
690
691
692 inode = path.dentry->d_inode;
693 dev = filp->private_data;
694
695 mutex_lock(&dev->up_mutex);
696 ret = inotify_find_update_watch(dev->ih, inode, mask);
697 if (ret == -ENOENT)
698 ret = create_watch(dev, inode, mask);
699 mutex_unlock(&dev->up_mutex);
700
701 path_put(&path);
702fput_and_out:
703 fput_light(filp, fput_needed);
704 return ret;
705}
706
707asmlinkage long sys_inotify_rm_watch(int fd, u32 wd)
708{
709 struct file *filp;
710 struct inotify_device *dev;
711 int ret, fput_needed;
712
713 filp = fget_light(fd, &fput_needed);
714 if (unlikely(!filp))
715 return -EBADF;
716
717
718 if (unlikely(filp->f_op != &inotify_fops)) {
719 ret = -EINVAL;
720 goto out;
721 }
722
723 dev = filp->private_data;
724
725
726 ret = inotify_rm_wd(dev->ih, wd);
727
728out:
729 fput_light(filp, fput_needed);
730 return ret;
731}
732
733static int
734inotify_get_sb(struct file_system_type *fs_type, int flags,
735 const char *dev_name, void *data, struct vfsmount *mnt)
736{
737 return get_sb_pseudo(fs_type, "inotify", NULL,
738 INOTIFYFS_SUPER_MAGIC, mnt);
739}
740
741static struct file_system_type inotify_fs_type = {
742 .name = "inotifyfs",
743 .get_sb = inotify_get_sb,
744 .kill_sb = kill_anon_super,
745};
746
747
748
749
750
751
752static int __init inotify_user_setup(void)
753{
754 int ret;
755
756 ret = register_filesystem(&inotify_fs_type);
757 if (unlikely(ret))
758 panic("inotify: register_filesystem returned %d!\n", ret);
759
760 inotify_mnt = kern_mount(&inotify_fs_type);
761 if (IS_ERR(inotify_mnt))
762 panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt));
763
764 inotify_max_queued_events = 16384;
765 inotify_max_user_instances = 128;
766 inotify_max_user_watches = 8192;
767
768 watch_cachep = kmem_cache_create("inotify_watch_cache",
769 sizeof(struct inotify_user_watch),
770 0, SLAB_PANIC, NULL);
771 event_cachep = kmem_cache_create("inotify_event_cache",
772 sizeof(struct inotify_kernel_event),
773 0, SLAB_PANIC, NULL);
774
775 return 0;
776}
777
778module_init(inotify_user_setup);