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Commit | Line | Data |
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2d9048e2 AG |
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 | * | |
63c882a0 EP |
11 | * Copyright (C) 2009 Eric Paris <Red Hat Inc> |
12 | * inotify was largely rewriten to make use of the fsnotify infrastructure | |
13 | * | |
2d9048e2 AG |
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 | ||
2d9048e2 | 25 | #include <linux/file.h> |
63c882a0 EP |
26 | #include <linux/fs.h> /* struct inode */ |
27 | #include <linux/fsnotify_backend.h> | |
28 | #include <linux/idr.h> | |
29 | #include <linux/init.h> /* module_init */ | |
2d9048e2 | 30 | #include <linux/inotify.h> |
63c882a0 EP |
31 | #include <linux/kernel.h> /* roundup() */ |
32 | #include <linux/magic.h> /* superblock magic number */ | |
33 | #include <linux/mount.h> /* mntget */ | |
34 | #include <linux/namei.h> /* LOOKUP_FOLLOW */ | |
35 | #include <linux/path.h> /* struct path */ | |
36 | #include <linux/sched.h> /* struct user */ | |
37 | #include <linux/slab.h> /* struct kmem_cache */ | |
2d9048e2 | 38 | #include <linux/syscalls.h> |
63c882a0 EP |
39 | #include <linux/types.h> |
40 | #include <linux/uaccess.h> | |
41 | #include <linux/poll.h> | |
42 | #include <linux/wait.h> | |
2d9048e2 | 43 | |
63c882a0 | 44 | #include "inotify.h" |
2d9048e2 | 45 | |
63c882a0 | 46 | #include <asm/ioctls.h> |
2d9048e2 AG |
47 | |
48 | static struct vfsmount *inotify_mnt __read_mostly; | |
49 | ||
63c882a0 EP |
50 | /* this just sits here and wastes global memory. used to just pad userspace messages with zeros */ |
51 | static struct inotify_event nul_inotify_event; | |
52 | ||
2d9048e2 | 53 | /* these are configurable via /proc/sys/fs/inotify/ */ |
3c828e49 | 54 | static int inotify_max_user_instances __read_mostly; |
3c828e49 | 55 | static int inotify_max_queued_events __read_mostly; |
63c882a0 | 56 | int inotify_max_user_watches __read_mostly; |
2d9048e2 | 57 | |
63c882a0 EP |
58 | static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; |
59 | struct kmem_cache *event_priv_cachep __read_mostly; | |
2d9048e2 AG |
60 | |
61 | /* | |
63c882a0 EP |
62 | * When inotify registers a new group it increments this and uses that |
63 | * value as an offset to set the fsnotify group "name" and priority. | |
2d9048e2 | 64 | */ |
63c882a0 | 65 | static atomic_t inotify_grp_num; |
2d9048e2 AG |
66 | |
67 | #ifdef CONFIG_SYSCTL | |
68 | ||
69 | #include <linux/sysctl.h> | |
70 | ||
71 | static int zero; | |
72 | ||
73 | ctl_table inotify_table[] = { | |
74 | { | |
75 | .ctl_name = INOTIFY_MAX_USER_INSTANCES, | |
76 | .procname = "max_user_instances", | |
77 | .data = &inotify_max_user_instances, | |
78 | .maxlen = sizeof(int), | |
79 | .mode = 0644, | |
80 | .proc_handler = &proc_dointvec_minmax, | |
81 | .strategy = &sysctl_intvec, | |
82 | .extra1 = &zero, | |
83 | }, | |
84 | { | |
85 | .ctl_name = INOTIFY_MAX_USER_WATCHES, | |
86 | .procname = "max_user_watches", | |
87 | .data = &inotify_max_user_watches, | |
88 | .maxlen = sizeof(int), | |
89 | .mode = 0644, | |
90 | .proc_handler = &proc_dointvec_minmax, | |
91 | .strategy = &sysctl_intvec, | |
92 | .extra1 = &zero, | |
93 | }, | |
94 | { | |
95 | .ctl_name = INOTIFY_MAX_QUEUED_EVENTS, | |
96 | .procname = "max_queued_events", | |
97 | .data = &inotify_max_queued_events, | |
98 | .maxlen = sizeof(int), | |
99 | .mode = 0644, | |
100 | .proc_handler = &proc_dointvec_minmax, | |
101 | .strategy = &sysctl_intvec, | |
102 | .extra1 = &zero | |
103 | }, | |
104 | { .ctl_name = 0 } | |
105 | }; | |
106 | #endif /* CONFIG_SYSCTL */ | |
107 | ||
63c882a0 | 108 | static inline __u32 inotify_arg_to_mask(u32 arg) |
1c17d18e | 109 | { |
63c882a0 | 110 | __u32 mask; |
1c17d18e | 111 | |
63c882a0 EP |
112 | /* everything should accept their own ignored and cares about children */ |
113 | mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD); | |
2d9048e2 | 114 | |
63c882a0 EP |
115 | /* mask off the flags used to open the fd */ |
116 | mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT)); | |
2d9048e2 | 117 | |
63c882a0 | 118 | return mask; |
2d9048e2 AG |
119 | } |
120 | ||
63c882a0 | 121 | static inline u32 inotify_mask_to_arg(__u32 mask) |
2d9048e2 | 122 | { |
63c882a0 EP |
123 | return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | |
124 | IN_Q_OVERFLOW); | |
2d9048e2 AG |
125 | } |
126 | ||
63c882a0 | 127 | /* intofiy userspace file descriptor functions */ |
2d9048e2 AG |
128 | static unsigned int inotify_poll(struct file *file, poll_table *wait) |
129 | { | |
63c882a0 | 130 | struct fsnotify_group *group = file->private_data; |
2d9048e2 AG |
131 | int ret = 0; |
132 | ||
63c882a0 EP |
133 | poll_wait(file, &group->notification_waitq, wait); |
134 | mutex_lock(&group->notification_mutex); | |
135 | if (!fsnotify_notify_queue_is_empty(group)) | |
2d9048e2 | 136 | ret = POLLIN | POLLRDNORM; |
63c882a0 | 137 | mutex_unlock(&group->notification_mutex); |
2d9048e2 AG |
138 | |
139 | return ret; | |
140 | } | |
141 | ||
3632dee2 VN |
142 | /* |
143 | * Get an inotify_kernel_event if one exists and is small | |
144 | * enough to fit in "count". Return an error pointer if | |
145 | * not large enough. | |
146 | * | |
63c882a0 | 147 | * Called with the group->notification_mutex held. |
3632dee2 | 148 | */ |
63c882a0 EP |
149 | static struct fsnotify_event *get_one_event(struct fsnotify_group *group, |
150 | size_t count) | |
3632dee2 VN |
151 | { |
152 | size_t event_size = sizeof(struct inotify_event); | |
63c882a0 | 153 | struct fsnotify_event *event; |
3632dee2 | 154 | |
63c882a0 | 155 | if (fsnotify_notify_queue_is_empty(group)) |
3632dee2 VN |
156 | return NULL; |
157 | ||
63c882a0 EP |
158 | event = fsnotify_peek_notify_event(group); |
159 | ||
160 | event_size += roundup(event->name_len, event_size); | |
3632dee2 VN |
161 | |
162 | if (event_size > count) | |
163 | return ERR_PTR(-EINVAL); | |
164 | ||
63c882a0 EP |
165 | /* held the notification_mutex the whole time, so this is the |
166 | * same event we peeked above */ | |
167 | fsnotify_remove_notify_event(group); | |
168 | ||
169 | return event; | |
3632dee2 VN |
170 | } |
171 | ||
172 | /* | |
173 | * Copy an event to user space, returning how much we copied. | |
174 | * | |
175 | * We already checked that the event size is smaller than the | |
176 | * buffer we had in "get_one_event()" above. | |
177 | */ | |
63c882a0 EP |
178 | static ssize_t copy_event_to_user(struct fsnotify_group *group, |
179 | struct fsnotify_event *event, | |
3632dee2 VN |
180 | char __user *buf) |
181 | { | |
63c882a0 EP |
182 | struct inotify_event inotify_event; |
183 | struct fsnotify_event_private_data *fsn_priv; | |
184 | struct inotify_event_private_data *priv; | |
3632dee2 | 185 | size_t event_size = sizeof(struct inotify_event); |
63c882a0 EP |
186 | size_t name_len; |
187 | ||
188 | /* we get the inotify watch descriptor from the event private data */ | |
189 | spin_lock(&event->lock); | |
190 | fsn_priv = fsnotify_remove_priv_from_event(group, event); | |
191 | spin_unlock(&event->lock); | |
192 | ||
193 | if (!fsn_priv) | |
194 | inotify_event.wd = -1; | |
195 | else { | |
196 | priv = container_of(fsn_priv, struct inotify_event_private_data, | |
197 | fsnotify_event_priv_data); | |
198 | inotify_event.wd = priv->wd; | |
199 | inotify_free_event_priv(fsn_priv); | |
200 | } | |
201 | ||
202 | /* round up event->name_len so it is a multiple of event_size */ | |
203 | name_len = roundup(event->name_len, event_size); | |
204 | inotify_event.len = name_len; | |
205 | ||
206 | inotify_event.mask = inotify_mask_to_arg(event->mask); | |
207 | inotify_event.cookie = event->sync_cookie; | |
3632dee2 | 208 | |
63c882a0 EP |
209 | /* send the main event */ |
210 | if (copy_to_user(buf, &inotify_event, event_size)) | |
3632dee2 VN |
211 | return -EFAULT; |
212 | ||
63c882a0 | 213 | buf += event_size; |
3632dee2 | 214 | |
63c882a0 EP |
215 | /* |
216 | * fsnotify only stores the pathname, so here we have to send the pathname | |
217 | * and then pad that pathname out to a multiple of sizeof(inotify_event) | |
218 | * with zeros. I get my zeros from the nul_inotify_event. | |
219 | */ | |
220 | if (name_len) { | |
221 | unsigned int len_to_zero = name_len - event->name_len; | |
222 | /* copy the path name */ | |
223 | if (copy_to_user(buf, event->file_name, event->name_len)) | |
3632dee2 | 224 | return -EFAULT; |
63c882a0 | 225 | buf += event->name_len; |
3632dee2 | 226 | |
63c882a0 EP |
227 | /* fill userspace with 0's from nul_inotify_event */ |
228 | if (copy_to_user(buf, &nul_inotify_event, len_to_zero)) | |
229 | return -EFAULT; | |
230 | buf += len_to_zero; | |
231 | event_size += name_len; | |
3632dee2 | 232 | } |
63c882a0 | 233 | |
3632dee2 VN |
234 | return event_size; |
235 | } | |
236 | ||
2d9048e2 AG |
237 | static ssize_t inotify_read(struct file *file, char __user *buf, |
238 | size_t count, loff_t *pos) | |
239 | { | |
63c882a0 EP |
240 | struct fsnotify_group *group; |
241 | struct fsnotify_event *kevent; | |
2d9048e2 AG |
242 | char __user *start; |
243 | int ret; | |
244 | DEFINE_WAIT(wait); | |
245 | ||
246 | start = buf; | |
63c882a0 | 247 | group = file->private_data; |
2d9048e2 AG |
248 | |
249 | while (1) { | |
63c882a0 | 250 | prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); |
2d9048e2 | 251 | |
63c882a0 EP |
252 | mutex_lock(&group->notification_mutex); |
253 | kevent = get_one_event(group, count); | |
254 | mutex_unlock(&group->notification_mutex); | |
2d9048e2 | 255 | |
3632dee2 VN |
256 | if (kevent) { |
257 | ret = PTR_ERR(kevent); | |
258 | if (IS_ERR(kevent)) | |
259 | break; | |
63c882a0 EP |
260 | ret = copy_event_to_user(group, kevent, buf); |
261 | fsnotify_put_event(kevent); | |
3632dee2 VN |
262 | if (ret < 0) |
263 | break; | |
264 | buf += ret; | |
265 | count -= ret; | |
266 | continue; | |
2d9048e2 AG |
267 | } |
268 | ||
3632dee2 VN |
269 | ret = -EAGAIN; |
270 | if (file->f_flags & O_NONBLOCK) | |
2d9048e2 | 271 | break; |
3632dee2 VN |
272 | ret = -EINTR; |
273 | if (signal_pending(current)) | |
2d9048e2 | 274 | break; |
16dbc6c9 | 275 | |
3632dee2 | 276 | if (start != buf) |
2d9048e2 | 277 | break; |
16dbc6c9 | 278 | |
3632dee2 | 279 | schedule(); |
2d9048e2 | 280 | } |
2d9048e2 | 281 | |
63c882a0 | 282 | finish_wait(&group->notification_waitq, &wait); |
3632dee2 VN |
283 | if (start != buf && ret != -EFAULT) |
284 | ret = buf - start; | |
2d9048e2 AG |
285 | return ret; |
286 | } | |
287 | ||
bcfbf84d DA |
288 | static int inotify_fasync(int fd, struct file *file, int on) |
289 | { | |
63c882a0 | 290 | struct fsnotify_group *group = file->private_data; |
bcfbf84d | 291 | |
63c882a0 | 292 | return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO; |
bcfbf84d DA |
293 | } |
294 | ||
2d9048e2 AG |
295 | static int inotify_release(struct inode *ignored, struct file *file) |
296 | { | |
63c882a0 | 297 | struct fsnotify_group *group = file->private_data; |
bdae997f | 298 | struct user_struct *user = group->inotify_data.user; |
2d9048e2 | 299 | |
63c882a0 | 300 | fsnotify_clear_marks_by_group(group); |
2d9048e2 | 301 | |
63c882a0 EP |
302 | /* free this group, matching get was inotify_init->fsnotify_obtain_group */ |
303 | fsnotify_put_group(group); | |
2d9048e2 | 304 | |
bdae997f KP |
305 | atomic_dec(&user->inotify_devs); |
306 | ||
2d9048e2 AG |
307 | return 0; |
308 | } | |
309 | ||
310 | static long inotify_ioctl(struct file *file, unsigned int cmd, | |
311 | unsigned long arg) | |
312 | { | |
63c882a0 EP |
313 | struct fsnotify_group *group; |
314 | struct fsnotify_event_holder *holder; | |
315 | struct fsnotify_event *event; | |
2d9048e2 AG |
316 | void __user *p; |
317 | int ret = -ENOTTY; | |
63c882a0 | 318 | size_t send_len = 0; |
2d9048e2 | 319 | |
63c882a0 | 320 | group = file->private_data; |
2d9048e2 AG |
321 | p = (void __user *) arg; |
322 | ||
323 | switch (cmd) { | |
324 | case FIONREAD: | |
63c882a0 EP |
325 | mutex_lock(&group->notification_mutex); |
326 | list_for_each_entry(holder, &group->notification_list, event_list) { | |
327 | event = holder->event; | |
328 | send_len += sizeof(struct inotify_event); | |
329 | send_len += roundup(event->name_len, | |
330 | sizeof(struct inotify_event)); | |
331 | } | |
332 | mutex_unlock(&group->notification_mutex); | |
333 | ret = put_user(send_len, (int __user *) p); | |
2d9048e2 AG |
334 | break; |
335 | } | |
336 | ||
337 | return ret; | |
338 | } | |
339 | ||
340 | static const struct file_operations inotify_fops = { | |
63c882a0 EP |
341 | .poll = inotify_poll, |
342 | .read = inotify_read, | |
343 | .fasync = inotify_fasync, | |
344 | .release = inotify_release, | |
345 | .unlocked_ioctl = inotify_ioctl, | |
2d9048e2 AG |
346 | .compat_ioctl = inotify_ioctl, |
347 | }; | |
348 | ||
2d9048e2 | 349 | |
63c882a0 EP |
350 | /* |
351 | * find_inode - resolve a user-given path to a specific inode | |
352 | */ | |
353 | static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags) | |
354 | { | |
355 | int error; | |
356 | ||
357 | error = user_path_at(AT_FDCWD, dirname, flags, path); | |
358 | if (error) | |
359 | return error; | |
360 | /* you can only watch an inode if you have read permissions on it */ | |
361 | error = inode_permission(path->dentry->d_inode, MAY_READ); | |
362 | if (error) | |
363 | path_put(path); | |
364 | return error; | |
365 | } | |
366 | ||
dead537d EP |
367 | /* |
368 | * Remove the mark from the idr (if present) and drop the reference | |
369 | * on the mark because it was in the idr. | |
370 | */ | |
7e790dd5 EP |
371 | static void inotify_remove_from_idr(struct fsnotify_group *group, |
372 | struct inotify_inode_mark_entry *ientry) | |
373 | { | |
374 | struct idr *idr; | |
dead537d EP |
375 | struct fsnotify_mark_entry *entry; |
376 | struct inotify_inode_mark_entry *found_ientry; | |
377 | int wd; | |
7e790dd5 EP |
378 | |
379 | spin_lock(&group->inotify_data.idr_lock); | |
380 | idr = &group->inotify_data.idr; | |
dead537d EP |
381 | wd = ientry->wd; |
382 | ||
383 | if (wd == -1) | |
384 | goto out; | |
385 | ||
386 | entry = idr_find(&group->inotify_data.idr, wd); | |
387 | if (unlikely(!entry)) | |
388 | goto out; | |
389 | ||
390 | found_ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); | |
391 | if (unlikely(found_ientry != ientry)) { | |
392 | /* We found an entry in the idr with the right wd, but it's | |
393 | * not the entry we were told to remove. eparis seriously | |
394 | * fucked up somewhere. */ | |
395 | WARN_ON(1); | |
396 | ientry->wd = -1; | |
397 | goto out; | |
398 | } | |
399 | ||
400 | /* One ref for being in the idr, one ref held by the caller */ | |
401 | BUG_ON(atomic_read(&entry->refcnt) < 2); | |
402 | ||
403 | idr_remove(idr, wd); | |
7e790dd5 | 404 | ientry->wd = -1; |
dead537d EP |
405 | |
406 | /* removed from the idr, drop that ref */ | |
407 | fsnotify_put_mark(entry); | |
408 | out: | |
409 | spin_unlock(&group->inotify_data.idr_lock); | |
7e790dd5 | 410 | } |
dead537d | 411 | |
63c882a0 | 412 | /* |
dead537d | 413 | * Send IN_IGNORED for this wd, remove this wd from the idr. |
63c882a0 | 414 | */ |
528da3e9 EP |
415 | void inotify_ignored_and_remove_idr(struct fsnotify_mark_entry *entry, |
416 | struct fsnotify_group *group) | |
63c882a0 EP |
417 | { |
418 | struct inotify_inode_mark_entry *ientry; | |
f44aebcc | 419 | struct fsnotify_event *ignored_event; |
63c882a0 EP |
420 | struct inotify_event_private_data *event_priv; |
421 | struct fsnotify_event_private_data *fsn_event_priv; | |
eef3a116 | 422 | int ret; |
63c882a0 | 423 | |
f44aebcc EP |
424 | ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, |
425 | FSNOTIFY_EVENT_NONE, NULL, 0, | |
426 | GFP_NOFS); | |
427 | if (!ignored_event) | |
428 | return; | |
429 | ||
63c882a0 EP |
430 | ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); |
431 | ||
f44aebcc | 432 | event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS); |
63c882a0 EP |
433 | if (unlikely(!event_priv)) |
434 | goto skip_send_ignore; | |
435 | ||
436 | fsn_event_priv = &event_priv->fsnotify_event_priv_data; | |
437 | ||
438 | fsn_event_priv->group = group; | |
439 | event_priv->wd = ientry->wd; | |
440 | ||
eef3a116 EP |
441 | ret = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv); |
442 | if (ret) | |
63c882a0 EP |
443 | inotify_free_event_priv(fsn_event_priv); |
444 | ||
445 | skip_send_ignore: | |
446 | ||
f44aebcc EP |
447 | /* matches the reference taken when the event was created */ |
448 | fsnotify_put_event(ignored_event); | |
449 | ||
63c882a0 | 450 | /* remove this entry from the idr */ |
7e790dd5 | 451 | inotify_remove_from_idr(group, ientry); |
63c882a0 | 452 | |
5549f7cd | 453 | atomic_dec(&group->inotify_data.user->inotify_watches); |
63c882a0 EP |
454 | } |
455 | ||
456 | /* ding dong the mark is dead */ | |
457 | static void inotify_free_mark(struct fsnotify_mark_entry *entry) | |
458 | { | |
459 | struct inotify_inode_mark_entry *ientry = (struct inotify_inode_mark_entry *)entry; | |
460 | ||
461 | kmem_cache_free(inotify_inode_mark_cachep, ientry); | |
462 | } | |
463 | ||
52cef755 EP |
464 | static int inotify_update_existing_watch(struct fsnotify_group *group, |
465 | struct inode *inode, | |
466 | u32 arg) | |
63c882a0 | 467 | { |
52cef755 | 468 | struct fsnotify_mark_entry *entry; |
63c882a0 | 469 | struct inotify_inode_mark_entry *ientry; |
63c882a0 | 470 | __u32 old_mask, new_mask; |
52cef755 EP |
471 | __u32 mask; |
472 | int add = (arg & IN_MASK_ADD); | |
473 | int ret; | |
63c882a0 EP |
474 | |
475 | /* don't allow invalid bits: we don't want flags set */ | |
476 | mask = inotify_arg_to_mask(arg); | |
477 | if (unlikely(!mask)) | |
478 | return -EINVAL; | |
479 | ||
63c882a0 EP |
480 | spin_lock(&inode->i_lock); |
481 | entry = fsnotify_find_mark_entry(group, inode); | |
482 | spin_unlock(&inode->i_lock); | |
52cef755 EP |
483 | if (!entry) |
484 | return -ENOENT; | |
7e790dd5 | 485 | |
52cef755 | 486 | ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry); |
75fe2b26 | 487 | |
63c882a0 EP |
488 | spin_lock(&entry->lock); |
489 | ||
490 | old_mask = entry->mask; | |
491 | if (add) { | |
492 | entry->mask |= mask; | |
493 | new_mask = entry->mask; | |
494 | } else { | |
495 | entry->mask = mask; | |
496 | new_mask = entry->mask; | |
497 | } | |
498 | ||
499 | spin_unlock(&entry->lock); | |
500 | ||
501 | if (old_mask != new_mask) { | |
502 | /* more bits in old than in new? */ | |
503 | int dropped = (old_mask & ~new_mask); | |
504 | /* more bits in this entry than the inode's mask? */ | |
505 | int do_inode = (new_mask & ~inode->i_fsnotify_mask); | |
506 | /* more bits in this entry than the group? */ | |
507 | int do_group = (new_mask & ~group->mask); | |
508 | ||
509 | /* update the inode with this new entry */ | |
510 | if (dropped || do_inode) | |
511 | fsnotify_recalc_inode_mask(inode); | |
512 | ||
513 | /* update the group mask with the new mask */ | |
514 | if (dropped || do_group) | |
515 | fsnotify_recalc_group_mask(group); | |
516 | } | |
517 | ||
52cef755 EP |
518 | /* return the wd */ |
519 | ret = ientry->wd; | |
520 | ||
521 | /* match the get from fsnotify_find_mark_entry() */ | |
75fe2b26 EP |
522 | fsnotify_put_mark(entry); |
523 | ||
52cef755 EP |
524 | return ret; |
525 | } | |
526 | ||
527 | static int inotify_new_watch(struct fsnotify_group *group, | |
528 | struct inode *inode, | |
529 | u32 arg) | |
530 | { | |
531 | struct inotify_inode_mark_entry *tmp_ientry; | |
532 | __u32 mask; | |
533 | int ret; | |
534 | ||
535 | /* don't allow invalid bits: we don't want flags set */ | |
536 | mask = inotify_arg_to_mask(arg); | |
537 | if (unlikely(!mask)) | |
538 | return -EINVAL; | |
539 | ||
540 | tmp_ientry = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); | |
541 | if (unlikely(!tmp_ientry)) | |
542 | return -ENOMEM; | |
543 | ||
544 | fsnotify_init_mark(&tmp_ientry->fsn_entry, inotify_free_mark); | |
545 | tmp_ientry->fsn_entry.mask = mask; | |
546 | tmp_ientry->wd = -1; | |
547 | ||
548 | ret = -ENOSPC; | |
549 | if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) | |
550 | goto out_err; | |
551 | retry: | |
552 | ret = -ENOMEM; | |
553 | if (unlikely(!idr_pre_get(&group->inotify_data.idr, GFP_KERNEL))) | |
554 | goto out_err; | |
555 | ||
556 | spin_lock(&group->inotify_data.idr_lock); | |
557 | ret = idr_get_new_above(&group->inotify_data.idr, &tmp_ientry->fsn_entry, | |
558 | group->inotify_data.last_wd, | |
559 | &tmp_ientry->wd); | |
560 | spin_unlock(&group->inotify_data.idr_lock); | |
561 | if (ret) { | |
562 | /* idr was out of memory allocate and try again */ | |
563 | if (ret == -EAGAIN) | |
564 | goto retry; | |
565 | goto out_err; | |
566 | } | |
567 | ||
dead537d EP |
568 | /* we put the mark on the idr, take a reference */ |
569 | fsnotify_get_mark(&tmp_ientry->fsn_entry); | |
570 | ||
52cef755 EP |
571 | /* we are on the idr, now get on the inode */ |
572 | ret = fsnotify_add_mark(&tmp_ientry->fsn_entry, group, inode); | |
573 | if (ret) { | |
574 | /* we failed to get on the inode, get off the idr */ | |
575 | inotify_remove_from_idr(group, tmp_ientry); | |
576 | goto out_err; | |
577 | } | |
578 | ||
52cef755 EP |
579 | /* update the idr hint, who cares about races, it's just a hint */ |
580 | group->inotify_data.last_wd = tmp_ientry->wd; | |
581 | ||
582 | /* increment the number of watches the user has */ | |
583 | atomic_inc(&group->inotify_data.user->inotify_watches); | |
584 | ||
585 | /* return the watch descriptor for this new entry */ | |
586 | ret = tmp_ientry->wd; | |
587 | ||
588 | /* match the ref from fsnotify_init_markentry() */ | |
589 | fsnotify_put_mark(&tmp_ientry->fsn_entry); | |
590 | ||
63c882a0 | 591 | out_err: |
52cef755 | 592 | if (ret < 0) |
7e790dd5 | 593 | kmem_cache_free(inotify_inode_mark_cachep, tmp_ientry); |
52cef755 EP |
594 | |
595 | return ret; | |
596 | } | |
597 | ||
598 | static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) | |
599 | { | |
600 | int ret = 0; | |
601 | ||
602 | retry: | |
603 | /* try to update and existing watch with the new arg */ | |
604 | ret = inotify_update_existing_watch(group, inode, arg); | |
605 | /* no mark present, try to add a new one */ | |
606 | if (ret == -ENOENT) | |
607 | ret = inotify_new_watch(group, inode, arg); | |
608 | /* | |
609 | * inotify_new_watch could race with another thread which did an | |
610 | * inotify_new_watch between the update_existing and the add watch | |
611 | * here, go back and try to update an existing mark again. | |
612 | */ | |
613 | if (ret == -EEXIST) | |
614 | goto retry; | |
7e790dd5 | 615 | |
63c882a0 EP |
616 | return ret; |
617 | } | |
618 | ||
619 | static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events) | |
620 | { | |
621 | struct fsnotify_group *group; | |
622 | unsigned int grp_num; | |
623 | ||
624 | /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ | |
625 | grp_num = (INOTIFY_GROUP_NUM - atomic_inc_return(&inotify_grp_num)); | |
626 | group = fsnotify_obtain_group(grp_num, 0, &inotify_fsnotify_ops); | |
627 | if (IS_ERR(group)) | |
628 | return group; | |
629 | ||
630 | group->max_events = max_events; | |
631 | ||
632 | spin_lock_init(&group->inotify_data.idr_lock); | |
633 | idr_init(&group->inotify_data.idr); | |
08e53fcb | 634 | group->inotify_data.last_wd = 1; |
63c882a0 EP |
635 | group->inotify_data.user = user; |
636 | group->inotify_data.fa = NULL; | |
637 | ||
638 | return group; | |
639 | } | |
640 | ||
641 | ||
642 | /* inotify syscalls */ | |
938bb9f5 | 643 | SYSCALL_DEFINE1(inotify_init1, int, flags) |
2d9048e2 | 644 | { |
63c882a0 | 645 | struct fsnotify_group *group; |
2d9048e2 AG |
646 | struct user_struct *user; |
647 | struct file *filp; | |
648 | int fd, ret; | |
649 | ||
e38b36f3 UD |
650 | /* Check the IN_* constants for consistency. */ |
651 | BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); | |
652 | BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); | |
653 | ||
510df2dd | 654 | if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) |
4006553b UD |
655 | return -EINVAL; |
656 | ||
657 | fd = get_unused_fd_flags(flags & O_CLOEXEC); | |
2d9048e2 AG |
658 | if (fd < 0) |
659 | return fd; | |
660 | ||
661 | filp = get_empty_filp(); | |
662 | if (!filp) { | |
663 | ret = -ENFILE; | |
664 | goto out_put_fd; | |
665 | } | |
666 | ||
da9592ed | 667 | user = get_current_user(); |
2d9048e2 AG |
668 | if (unlikely(atomic_read(&user->inotify_devs) >= |
669 | inotify_max_user_instances)) { | |
670 | ret = -EMFILE; | |
671 | goto out_free_uid; | |
672 | } | |
673 | ||
63c882a0 EP |
674 | /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ |
675 | group = inotify_new_group(user, inotify_max_queued_events); | |
676 | if (IS_ERR(group)) { | |
677 | ret = PTR_ERR(group); | |
2d9048e2 AG |
678 | goto out_free_uid; |
679 | } | |
680 | ||
2d9048e2 | 681 | filp->f_op = &inotify_fops; |
0f7fc9e4 JJS |
682 | filp->f_path.mnt = mntget(inotify_mnt); |
683 | filp->f_path.dentry = dget(inotify_mnt->mnt_root); | |
684 | filp->f_mapping = filp->f_path.dentry->d_inode->i_mapping; | |
2d9048e2 | 685 | filp->f_mode = FMODE_READ; |
510df2dd | 686 | filp->f_flags = O_RDONLY | (flags & O_NONBLOCK); |
63c882a0 EP |
687 | filp->private_data = group; |
688 | ||
2d9048e2 | 689 | atomic_inc(&user->inotify_devs); |
63c882a0 | 690 | |
2d9048e2 AG |
691 | fd_install(fd, filp); |
692 | ||
693 | return fd; | |
63c882a0 | 694 | |
2d9048e2 AG |
695 | out_free_uid: |
696 | free_uid(user); | |
697 | put_filp(filp); | |
698 | out_put_fd: | |
699 | put_unused_fd(fd); | |
700 | return ret; | |
701 | } | |
702 | ||
938bb9f5 | 703 | SYSCALL_DEFINE0(inotify_init) |
4006553b UD |
704 | { |
705 | return sys_inotify_init1(0); | |
706 | } | |
707 | ||
2e4d0924 HC |
708 | SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, |
709 | u32, mask) | |
2d9048e2 | 710 | { |
63c882a0 | 711 | struct fsnotify_group *group; |
2d9048e2 | 712 | struct inode *inode; |
2d8f3038 | 713 | struct path path; |
2d9048e2 AG |
714 | struct file *filp; |
715 | int ret, fput_needed; | |
716 | unsigned flags = 0; | |
717 | ||
718 | filp = fget_light(fd, &fput_needed); | |
719 | if (unlikely(!filp)) | |
720 | return -EBADF; | |
721 | ||
722 | /* verify that this is indeed an inotify instance */ | |
723 | if (unlikely(filp->f_op != &inotify_fops)) { | |
724 | ret = -EINVAL; | |
725 | goto fput_and_out; | |
726 | } | |
727 | ||
728 | if (!(mask & IN_DONT_FOLLOW)) | |
729 | flags |= LOOKUP_FOLLOW; | |
730 | if (mask & IN_ONLYDIR) | |
731 | flags |= LOOKUP_DIRECTORY; | |
732 | ||
63c882a0 EP |
733 | ret = inotify_find_inode(pathname, &path, flags); |
734 | if (ret) | |
2d9048e2 AG |
735 | goto fput_and_out; |
736 | ||
63c882a0 | 737 | /* inode held in place by reference to path; group by fget on fd */ |
2d8f3038 | 738 | inode = path.dentry->d_inode; |
63c882a0 | 739 | group = filp->private_data; |
2d9048e2 | 740 | |
63c882a0 EP |
741 | /* create/update an inode mark */ |
742 | ret = inotify_update_watch(group, inode, mask); | |
743 | if (unlikely(ret)) | |
744 | goto path_put_and_out; | |
2d9048e2 | 745 | |
63c882a0 | 746 | path_put_and_out: |
2d8f3038 | 747 | path_put(&path); |
2d9048e2 AG |
748 | fput_and_out: |
749 | fput_light(filp, fput_needed); | |
750 | return ret; | |
751 | } | |
752 | ||
2e4d0924 | 753 | SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) |
2d9048e2 | 754 | { |
63c882a0 EP |
755 | struct fsnotify_group *group; |
756 | struct fsnotify_mark_entry *entry; | |
2d9048e2 | 757 | struct file *filp; |
63c882a0 | 758 | int ret = 0, fput_needed; |
2d9048e2 AG |
759 | |
760 | filp = fget_light(fd, &fput_needed); | |
761 | if (unlikely(!filp)) | |
762 | return -EBADF; | |
763 | ||
764 | /* verify that this is indeed an inotify instance */ | |
765 | if (unlikely(filp->f_op != &inotify_fops)) { | |
766 | ret = -EINVAL; | |
767 | goto out; | |
768 | } | |
769 | ||
63c882a0 | 770 | group = filp->private_data; |
2d9048e2 | 771 | |
63c882a0 EP |
772 | spin_lock(&group->inotify_data.idr_lock); |
773 | entry = idr_find(&group->inotify_data.idr, wd); | |
774 | if (unlikely(!entry)) { | |
775 | spin_unlock(&group->inotify_data.idr_lock); | |
776 | ret = -EINVAL; | |
777 | goto out; | |
778 | } | |
779 | fsnotify_get_mark(entry); | |
780 | spin_unlock(&group->inotify_data.idr_lock); | |
781 | ||
528da3e9 | 782 | fsnotify_destroy_mark_by_entry(entry); |
63c882a0 | 783 | fsnotify_put_mark(entry); |
2d9048e2 AG |
784 | |
785 | out: | |
786 | fput_light(filp, fput_needed); | |
787 | return ret; | |
788 | } | |
789 | ||
454e2398 | 790 | static int |
2d9048e2 | 791 | inotify_get_sb(struct file_system_type *fs_type, int flags, |
454e2398 | 792 | const char *dev_name, void *data, struct vfsmount *mnt) |
2d9048e2 | 793 | { |
fd5eea42 AM |
794 | return get_sb_pseudo(fs_type, "inotify", NULL, |
795 | INOTIFYFS_SUPER_MAGIC, mnt); | |
2d9048e2 AG |
796 | } |
797 | ||
798 | static struct file_system_type inotify_fs_type = { | |
63c882a0 EP |
799 | .name = "inotifyfs", |
800 | .get_sb = inotify_get_sb, | |
801 | .kill_sb = kill_anon_super, | |
2d9048e2 AG |
802 | }; |
803 | ||
804 | /* | |
805 | * inotify_user_setup - Our initialization function. Note that we cannnot return | |
806 | * error because we have compiled-in VFS hooks. So an (unlikely) failure here | |
807 | * must result in panic(). | |
808 | */ | |
809 | static int __init inotify_user_setup(void) | |
810 | { | |
811 | int ret; | |
812 | ||
813 | ret = register_filesystem(&inotify_fs_type); | |
814 | if (unlikely(ret)) | |
815 | panic("inotify: register_filesystem returned %d!\n", ret); | |
816 | ||
817 | inotify_mnt = kern_mount(&inotify_fs_type); | |
818 | if (IS_ERR(inotify_mnt)) | |
819 | panic("inotify: kern_mount ret %ld!\n", PTR_ERR(inotify_mnt)); | |
820 | ||
63c882a0 EP |
821 | inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark_entry, SLAB_PANIC); |
822 | event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC); | |
63c882a0 | 823 | |
2d9048e2 AG |
824 | inotify_max_queued_events = 16384; |
825 | inotify_max_user_instances = 128; | |
826 | inotify_max_user_watches = 8192; | |
827 | ||
2d9048e2 AG |
828 | return 0; |
829 | } | |
2d9048e2 | 830 | module_init(inotify_user_setup); |