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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 | ||
23 | extern const struct fsnotify_ops fanotify_fsnotify_ops; | |
24 | ||
25 | static struct kmem_cache *fanotify_mark_cache __read_mostly; | |
26 | static struct kmem_cache *fanotify_response_event_cache __read_mostly; | |
27 | ||
28 | struct 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 | */ | |
41 | static 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 | ||
59 | static 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 | ||
109 | static ssize_t fill_event_metadata(struct fsnotify_group *group, | |
110 | struct fanotify_event_metadata *metadata, | |
111 | struct fsnotify_event *event) | |
112 | { | |
113 | pr_debug("%s: group=%p metadata=%p event=%p\n", __func__, | |
114 | group, metadata, event); | |
115 | ||
116 | metadata->event_len = FAN_EVENT_METADATA_LEN; | |
117 | metadata->vers = FANOTIFY_METADATA_VERSION; | |
118 | metadata->mask = event->mask & FAN_ALL_OUTGOING_EVENTS; | |
119 | metadata->pid = pid_vnr(event->tgid); | |
120 | metadata->fd = create_fd(group, event); | |
121 | ||
122 | return metadata->fd; | |
123 | } | |
124 | ||
125 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
126 | static struct fanotify_response_event *dequeue_re(struct fsnotify_group *group, | |
127 | __s32 fd) | |
128 | { | |
129 | struct fanotify_response_event *re, *return_re = NULL; | |
130 | ||
131 | mutex_lock(&group->fanotify_data.access_mutex); | |
132 | list_for_each_entry(re, &group->fanotify_data.access_list, list) { | |
133 | if (re->fd != fd) | |
134 | continue; | |
135 | ||
136 | list_del_init(&re->list); | |
137 | return_re = re; | |
138 | break; | |
139 | } | |
140 | mutex_unlock(&group->fanotify_data.access_mutex); | |
141 | ||
142 | pr_debug("%s: found return_re=%p\n", __func__, return_re); | |
143 | ||
144 | return return_re; | |
145 | } | |
146 | ||
147 | static int process_access_response(struct fsnotify_group *group, | |
148 | struct fanotify_response *response_struct) | |
149 | { | |
150 | struct fanotify_response_event *re; | |
151 | __s32 fd = response_struct->fd; | |
152 | __u32 response = response_struct->response; | |
153 | ||
154 | pr_debug("%s: group=%p fd=%d response=%d\n", __func__, group, | |
155 | fd, response); | |
156 | /* | |
157 | * make sure the response is valid, if invalid we do nothing and either | |
158 | * userspace can send a valid responce or we will clean it up after the | |
159 | * timeout | |
160 | */ | |
161 | switch (response) { | |
162 | case FAN_ALLOW: | |
163 | case FAN_DENY: | |
164 | break; | |
165 | default: | |
166 | return -EINVAL; | |
167 | } | |
168 | ||
169 | if (fd < 0) | |
170 | return -EINVAL; | |
171 | ||
172 | re = dequeue_re(group, fd); | |
173 | if (!re) | |
174 | return -ENOENT; | |
175 | ||
176 | re->event->response = response; | |
177 | ||
178 | wake_up(&group->fanotify_data.access_waitq); | |
179 | ||
180 | kmem_cache_free(fanotify_response_event_cache, re); | |
181 | ||
182 | return 0; | |
183 | } | |
184 | ||
185 | static int prepare_for_access_response(struct fsnotify_group *group, | |
186 | struct fsnotify_event *event, | |
187 | __s32 fd) | |
188 | { | |
189 | struct fanotify_response_event *re; | |
190 | ||
191 | if (!(event->mask & FAN_ALL_PERM_EVENTS)) | |
192 | return 0; | |
193 | ||
194 | re = kmem_cache_alloc(fanotify_response_event_cache, GFP_KERNEL); | |
195 | if (!re) | |
196 | return -ENOMEM; | |
197 | ||
198 | re->event = event; | |
199 | re->fd = fd; | |
200 | ||
201 | mutex_lock(&group->fanotify_data.access_mutex); | |
202 | ||
203 | if (group->fanotify_data.bypass_perm) { | |
204 | mutex_unlock(&group->fanotify_data.access_mutex); | |
205 | kmem_cache_free(fanotify_response_event_cache, re); | |
206 | event->response = FAN_ALLOW; | |
207 | return 0; | |
208 | } | |
209 | ||
210 | list_add_tail(&re->list, &group->fanotify_data.access_list); | |
211 | mutex_unlock(&group->fanotify_data.access_mutex); | |
212 | ||
213 | return 0; | |
214 | } | |
215 | ||
216 | static void remove_access_response(struct fsnotify_group *group, | |
217 | struct fsnotify_event *event, | |
218 | __s32 fd) | |
219 | { | |
220 | struct fanotify_response_event *re; | |
221 | ||
222 | if (!(event->mask & FAN_ALL_PERM_EVENTS)) | |
223 | return; | |
224 | ||
225 | re = dequeue_re(group, fd); | |
226 | if (!re) | |
227 | return; | |
228 | ||
229 | BUG_ON(re->event != event); | |
230 | ||
231 | kmem_cache_free(fanotify_response_event_cache, re); | |
232 | ||
233 | return; | |
234 | } | |
235 | #else | |
236 | static int prepare_for_access_response(struct fsnotify_group *group, | |
237 | struct fsnotify_event *event, | |
238 | __s32 fd) | |
239 | { | |
240 | return 0; | |
241 | } | |
242 | ||
243 | static void remove_access_response(struct fsnotify_group *group, | |
244 | struct fsnotify_event *event, | |
245 | __s32 fd) | |
246 | { | |
247 | return; | |
248 | } | |
249 | #endif | |
250 | ||
251 | static ssize_t copy_event_to_user(struct fsnotify_group *group, | |
252 | struct fsnotify_event *event, | |
253 | char __user *buf) | |
254 | { | |
255 | struct fanotify_event_metadata fanotify_event_metadata; | |
256 | int fd, ret; | |
257 | ||
258 | pr_debug("%s: group=%p event=%p\n", __func__, group, event); | |
259 | ||
260 | fd = fill_event_metadata(group, &fanotify_event_metadata, event); | |
261 | if (fd < 0) | |
262 | return fd; | |
263 | ||
264 | ret = prepare_for_access_response(group, event, fd); | |
265 | if (ret) | |
266 | goto out_close_fd; | |
267 | ||
268 | ret = -EFAULT; | |
269 | if (copy_to_user(buf, &fanotify_event_metadata, FAN_EVENT_METADATA_LEN)) | |
270 | goto out_kill_access_response; | |
271 | ||
272 | return FAN_EVENT_METADATA_LEN; | |
273 | ||
274 | out_kill_access_response: | |
275 | remove_access_response(group, event, fd); | |
276 | out_close_fd: | |
277 | sys_close(fd); | |
278 | return ret; | |
279 | } | |
280 | ||
281 | /* intofiy userspace file descriptor functions */ | |
282 | static unsigned int fanotify_poll(struct file *file, poll_table *wait) | |
283 | { | |
284 | struct fsnotify_group *group = file->private_data; | |
285 | int ret = 0; | |
286 | ||
287 | poll_wait(file, &group->notification_waitq, wait); | |
288 | mutex_lock(&group->notification_mutex); | |
289 | if (!fsnotify_notify_queue_is_empty(group)) | |
290 | ret = POLLIN | POLLRDNORM; | |
291 | mutex_unlock(&group->notification_mutex); | |
292 | ||
293 | return ret; | |
294 | } | |
295 | ||
296 | static ssize_t fanotify_read(struct file *file, char __user *buf, | |
297 | size_t count, loff_t *pos) | |
298 | { | |
299 | struct fsnotify_group *group; | |
300 | struct fsnotify_event *kevent; | |
301 | char __user *start; | |
302 | int ret; | |
303 | DEFINE_WAIT(wait); | |
304 | ||
305 | start = buf; | |
306 | group = file->private_data; | |
307 | ||
308 | pr_debug("%s: group=%p\n", __func__, group); | |
309 | ||
310 | while (1) { | |
311 | prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); | |
312 | ||
313 | mutex_lock(&group->notification_mutex); | |
314 | kevent = get_one_event(group, count); | |
315 | mutex_unlock(&group->notification_mutex); | |
316 | ||
317 | if (kevent) { | |
318 | ret = PTR_ERR(kevent); | |
319 | if (IS_ERR(kevent)) | |
320 | break; | |
321 | ret = copy_event_to_user(group, kevent, buf); | |
322 | fsnotify_put_event(kevent); | |
323 | if (ret < 0) | |
324 | break; | |
325 | buf += ret; | |
326 | count -= ret; | |
327 | continue; | |
328 | } | |
329 | ||
330 | ret = -EAGAIN; | |
331 | if (file->f_flags & O_NONBLOCK) | |
332 | break; | |
333 | ret = -ERESTARTSYS; | |
334 | if (signal_pending(current)) | |
335 | break; | |
336 | ||
337 | if (start != buf) | |
338 | break; | |
339 | ||
340 | schedule(); | |
341 | } | |
342 | ||
343 | finish_wait(&group->notification_waitq, &wait); | |
344 | if (start != buf && ret != -EFAULT) | |
345 | ret = buf - start; | |
346 | return ret; | |
347 | } | |
348 | ||
349 | static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos) | |
350 | { | |
351 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
352 | struct fanotify_response response = { .fd = -1, .response = -1 }; | |
353 | struct fsnotify_group *group; | |
354 | int ret; | |
355 | ||
356 | group = file->private_data; | |
357 | ||
358 | if (count > sizeof(response)) | |
359 | count = sizeof(response); | |
360 | ||
361 | pr_debug("%s: group=%p count=%zu\n", __func__, group, count); | |
362 | ||
363 | if (copy_from_user(&response, buf, count)) | |
364 | return -EFAULT; | |
365 | ||
366 | ret = process_access_response(group, &response); | |
367 | if (ret < 0) | |
368 | count = ret; | |
369 | ||
370 | return count; | |
371 | #else | |
372 | return -EINVAL; | |
373 | #endif | |
374 | } | |
375 | ||
376 | static int fanotify_release(struct inode *ignored, struct file *file) | |
377 | { | |
378 | struct fsnotify_group *group = file->private_data; | |
379 | ||
380 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
381 | struct fanotify_response_event *re, *lre; | |
382 | ||
383 | mutex_lock(&group->fanotify_data.access_mutex); | |
384 | ||
385 | group->fanotify_data.bypass_perm = true; | |
386 | ||
387 | list_for_each_entry_safe(re, lre, &group->fanotify_data.access_list, list) { | |
388 | pr_debug("%s: found group=%p re=%p event=%p\n", __func__, group, | |
389 | re, re->event); | |
390 | ||
391 | list_del_init(&re->list); | |
392 | re->event->response = FAN_ALLOW; | |
393 | ||
394 | kmem_cache_free(fanotify_response_event_cache, re); | |
395 | } | |
396 | mutex_unlock(&group->fanotify_data.access_mutex); | |
397 | ||
398 | wake_up(&group->fanotify_data.access_waitq); | |
399 | #endif | |
400 | /* matches the fanotify_init->fsnotify_alloc_group */ | |
401 | fsnotify_put_group(group); | |
402 | ||
403 | return 0; | |
404 | } | |
405 | ||
406 | static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg) | |
407 | { | |
408 | struct fsnotify_group *group; | |
409 | struct fsnotify_event_holder *holder; | |
410 | void __user *p; | |
411 | int ret = -ENOTTY; | |
412 | size_t send_len = 0; | |
413 | ||
414 | group = file->private_data; | |
415 | ||
416 | p = (void __user *) arg; | |
417 | ||
418 | switch (cmd) { | |
419 | case FIONREAD: | |
420 | mutex_lock(&group->notification_mutex); | |
421 | list_for_each_entry(holder, &group->notification_list, event_list) | |
422 | send_len += FAN_EVENT_METADATA_LEN; | |
423 | mutex_unlock(&group->notification_mutex); | |
424 | ret = put_user(send_len, (int __user *) p); | |
425 | break; | |
426 | } | |
427 | ||
428 | return ret; | |
429 | } | |
430 | ||
431 | static const struct file_operations fanotify_fops = { | |
432 | .poll = fanotify_poll, | |
433 | .read = fanotify_read, | |
434 | .write = fanotify_write, | |
435 | .fasync = NULL, | |
436 | .release = fanotify_release, | |
437 | .unlocked_ioctl = fanotify_ioctl, | |
438 | .compat_ioctl = fanotify_ioctl, | |
439 | .llseek = noop_llseek, | |
440 | }; | |
441 | ||
442 | static void fanotify_free_mark(struct fsnotify_mark *fsn_mark) | |
443 | { | |
444 | kmem_cache_free(fanotify_mark_cache, fsn_mark); | |
445 | } | |
446 | ||
447 | static int fanotify_find_path(int dfd, const char __user *filename, | |
448 | struct path *path, unsigned int flags) | |
449 | { | |
450 | int ret; | |
451 | ||
452 | pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__, | |
453 | dfd, filename, flags); | |
454 | ||
455 | if (filename == NULL) { | |
456 | struct file *file; | |
457 | int fput_needed; | |
458 | ||
459 | ret = -EBADF; | |
460 | file = fget_light(dfd, &fput_needed); | |
461 | if (!file) | |
462 | goto out; | |
463 | ||
464 | ret = -ENOTDIR; | |
465 | if ((flags & FAN_MARK_ONLYDIR) && | |
466 | !(S_ISDIR(file->f_path.dentry->d_inode->i_mode))) { | |
467 | fput_light(file, fput_needed); | |
468 | goto out; | |
469 | } | |
470 | ||
471 | *path = file->f_path; | |
472 | path_get(path); | |
473 | fput_light(file, fput_needed); | |
474 | } else { | |
475 | unsigned int lookup_flags = 0; | |
476 | ||
477 | if (!(flags & FAN_MARK_DONT_FOLLOW)) | |
478 | lookup_flags |= LOOKUP_FOLLOW; | |
479 | if (flags & FAN_MARK_ONLYDIR) | |
480 | lookup_flags |= LOOKUP_DIRECTORY; | |
481 | ||
482 | ret = user_path_at(dfd, filename, lookup_flags, path); | |
483 | if (ret) | |
484 | goto out; | |
485 | } | |
486 | ||
487 | /* you can only watch an inode if you have read permissions on it */ | |
488 | ret = inode_permission(path->dentry->d_inode, MAY_READ); | |
489 | if (ret) | |
490 | path_put(path); | |
491 | out: | |
492 | return ret; | |
493 | } | |
494 | ||
495 | static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark, | |
496 | __u32 mask, | |
497 | unsigned int flags) | |
498 | { | |
499 | __u32 oldmask; | |
500 | ||
501 | spin_lock(&fsn_mark->lock); | |
502 | if (!(flags & FAN_MARK_IGNORED_MASK)) { | |
503 | oldmask = fsn_mark->mask; | |
504 | fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask)); | |
505 | } else { | |
506 | oldmask = fsn_mark->ignored_mask; | |
507 | fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask)); | |
508 | } | |
509 | spin_unlock(&fsn_mark->lock); | |
510 | ||
511 | if (!(oldmask & ~mask)) | |
512 | fsnotify_destroy_mark(fsn_mark); | |
513 | ||
514 | return mask & oldmask; | |
515 | } | |
516 | ||
517 | static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group, | |
518 | struct vfsmount *mnt, __u32 mask, | |
519 | unsigned int flags) | |
520 | { | |
521 | struct fsnotify_mark *fsn_mark = NULL; | |
522 | __u32 removed; | |
523 | ||
524 | fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); | |
525 | if (!fsn_mark) | |
526 | return -ENOENT; | |
527 | ||
528 | removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags); | |
529 | fsnotify_put_mark(fsn_mark); | |
530 | if (removed & mnt->mnt_fsnotify_mask) | |
531 | fsnotify_recalc_vfsmount_mask(mnt); | |
532 | ||
533 | return 0; | |
534 | } | |
535 | ||
536 | static int fanotify_remove_inode_mark(struct fsnotify_group *group, | |
537 | struct inode *inode, __u32 mask, | |
538 | unsigned int flags) | |
539 | { | |
540 | struct fsnotify_mark *fsn_mark = NULL; | |
541 | __u32 removed; | |
542 | ||
543 | fsn_mark = fsnotify_find_inode_mark(group, inode); | |
544 | if (!fsn_mark) | |
545 | return -ENOENT; | |
546 | ||
547 | removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags); | |
548 | /* matches the fsnotify_find_inode_mark() */ | |
549 | fsnotify_put_mark(fsn_mark); | |
550 | if (removed & inode->i_fsnotify_mask) | |
551 | fsnotify_recalc_inode_mask(inode); | |
552 | ||
553 | return 0; | |
554 | } | |
555 | ||
556 | static __u32 fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark, | |
557 | __u32 mask, | |
558 | unsigned int flags) | |
559 | { | |
560 | __u32 oldmask = -1; | |
561 | ||
562 | spin_lock(&fsn_mark->lock); | |
563 | if (!(flags & FAN_MARK_IGNORED_MASK)) { | |
564 | oldmask = fsn_mark->mask; | |
565 | fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask)); | |
566 | } else { | |
567 | __u32 tmask = fsn_mark->ignored_mask | mask; | |
568 | fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); | |
569 | if (flags & FAN_MARK_IGNORED_SURV_MODIFY) | |
570 | fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY; | |
571 | } | |
572 | ||
573 | if (!(flags & FAN_MARK_ONDIR)) { | |
574 | __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR; | |
575 | fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask); | |
576 | } | |
577 | ||
578 | spin_unlock(&fsn_mark->lock); | |
579 | ||
580 | return mask & ~oldmask; | |
581 | } | |
582 | ||
583 | static int fanotify_add_vfsmount_mark(struct fsnotify_group *group, | |
584 | struct vfsmount *mnt, __u32 mask, | |
585 | unsigned int flags) | |
586 | { | |
587 | struct fsnotify_mark *fsn_mark; | |
588 | __u32 added; | |
589 | ||
590 | fsn_mark = fsnotify_find_vfsmount_mark(group, mnt); | |
591 | if (!fsn_mark) { | |
592 | int ret; | |
593 | ||
594 | if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) | |
595 | return -ENOSPC; | |
596 | ||
597 | fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); | |
598 | if (!fsn_mark) | |
599 | return -ENOMEM; | |
600 | ||
601 | fsnotify_init_mark(fsn_mark, fanotify_free_mark); | |
602 | ret = fsnotify_add_mark(fsn_mark, group, NULL, mnt, 0); | |
603 | if (ret) { | |
604 | fanotify_free_mark(fsn_mark); | |
605 | return ret; | |
606 | } | |
607 | } | |
608 | added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); | |
609 | fsnotify_put_mark(fsn_mark); | |
610 | if (added & ~mnt->mnt_fsnotify_mask) | |
611 | fsnotify_recalc_vfsmount_mask(mnt); | |
612 | ||
613 | return 0; | |
614 | } | |
615 | ||
616 | static int fanotify_add_inode_mark(struct fsnotify_group *group, | |
617 | struct inode *inode, __u32 mask, | |
618 | unsigned int flags) | |
619 | { | |
620 | struct fsnotify_mark *fsn_mark; | |
621 | __u32 added; | |
622 | ||
623 | pr_debug("%s: group=%p inode=%p\n", __func__, group, inode); | |
624 | ||
625 | /* | |
626 | * If some other task has this inode open for write we should not add | |
627 | * an ignored mark, unless that ignored mark is supposed to survive | |
628 | * modification changes anyway. | |
629 | */ | |
630 | if ((flags & FAN_MARK_IGNORED_MASK) && | |
631 | !(flags & FAN_MARK_IGNORED_SURV_MODIFY) && | |
632 | (atomic_read(&inode->i_writecount) > 0)) | |
633 | return 0; | |
634 | ||
635 | fsn_mark = fsnotify_find_inode_mark(group, inode); | |
636 | if (!fsn_mark) { | |
637 | int ret; | |
638 | ||
639 | if (atomic_read(&group->num_marks) > group->fanotify_data.max_marks) | |
640 | return -ENOSPC; | |
641 | ||
642 | fsn_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL); | |
643 | if (!fsn_mark) | |
644 | return -ENOMEM; | |
645 | ||
646 | fsnotify_init_mark(fsn_mark, fanotify_free_mark); | |
647 | ret = fsnotify_add_mark(fsn_mark, group, inode, NULL, 0); | |
648 | if (ret) { | |
649 | fanotify_free_mark(fsn_mark); | |
650 | return ret; | |
651 | } | |
652 | } | |
653 | added = fanotify_mark_add_to_mask(fsn_mark, mask, flags); | |
654 | fsnotify_put_mark(fsn_mark); | |
655 | if (added & ~inode->i_fsnotify_mask) | |
656 | fsnotify_recalc_inode_mask(inode); | |
657 | return 0; | |
658 | } | |
659 | ||
660 | /* fanotify syscalls */ | |
661 | SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) | |
662 | { | |
663 | struct fsnotify_group *group; | |
664 | int f_flags, fd; | |
665 | struct user_struct *user; | |
666 | ||
667 | pr_debug("%s: flags=%d event_f_flags=%d\n", | |
668 | __func__, flags, event_f_flags); | |
669 | ||
670 | if (!capable(CAP_SYS_ADMIN)) | |
671 | return -EPERM; | |
672 | ||
673 | if (flags & ~FAN_ALL_INIT_FLAGS) | |
674 | return -EINVAL; | |
675 | ||
676 | user = get_current_user(); | |
677 | if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) { | |
678 | free_uid(user); | |
679 | return -EMFILE; | |
680 | } | |
681 | ||
682 | f_flags = O_RDWR | FMODE_NONOTIFY; | |
683 | if (flags & FAN_CLOEXEC) | |
684 | f_flags |= O_CLOEXEC; | |
685 | if (flags & FAN_NONBLOCK) | |
686 | f_flags |= O_NONBLOCK; | |
687 | ||
688 | /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */ | |
689 | group = fsnotify_alloc_group(&fanotify_fsnotify_ops); | |
690 | if (IS_ERR(group)) | |
691 | return PTR_ERR(group); | |
692 | ||
693 | group->fanotify_data.user = user; | |
694 | atomic_inc(&user->fanotify_listeners); | |
695 | ||
696 | group->fanotify_data.f_flags = event_f_flags; | |
697 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
698 | mutex_init(&group->fanotify_data.access_mutex); | |
699 | init_waitqueue_head(&group->fanotify_data.access_waitq); | |
700 | INIT_LIST_HEAD(&group->fanotify_data.access_list); | |
701 | #endif | |
702 | switch (flags & FAN_ALL_CLASS_BITS) { | |
703 | case FAN_CLASS_NOTIF: | |
704 | group->priority = FS_PRIO_0; | |
705 | break; | |
706 | case FAN_CLASS_CONTENT: | |
707 | group->priority = FS_PRIO_1; | |
708 | break; | |
709 | case FAN_CLASS_PRE_CONTENT: | |
710 | group->priority = FS_PRIO_2; | |
711 | break; | |
712 | default: | |
713 | fd = -EINVAL; | |
714 | goto out_put_group; | |
715 | } | |
716 | ||
717 | if (flags & FAN_UNLIMITED_QUEUE) { | |
718 | fd = -EPERM; | |
719 | if (!capable(CAP_SYS_ADMIN)) | |
720 | goto out_put_group; | |
721 | group->max_events = UINT_MAX; | |
722 | } else { | |
723 | group->max_events = FANOTIFY_DEFAULT_MAX_EVENTS; | |
724 | } | |
725 | ||
726 | if (flags & FAN_UNLIMITED_MARKS) { | |
727 | fd = -EPERM; | |
728 | if (!capable(CAP_SYS_ADMIN)) | |
729 | goto out_put_group; | |
730 | group->fanotify_data.max_marks = UINT_MAX; | |
731 | } else { | |
732 | group->fanotify_data.max_marks = FANOTIFY_DEFAULT_MAX_MARKS; | |
733 | } | |
734 | ||
735 | fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags); | |
736 | if (fd < 0) | |
737 | goto out_put_group; | |
738 | ||
739 | return fd; | |
740 | ||
741 | out_put_group: | |
742 | fsnotify_put_group(group); | |
743 | return fd; | |
744 | } | |
745 | ||
746 | SYSCALL_DEFINE(fanotify_mark)(int fanotify_fd, unsigned int flags, | |
747 | __u64 mask, int dfd, | |
748 | const char __user * pathname) | |
749 | { | |
750 | struct inode *inode = NULL; | |
751 | struct vfsmount *mnt = NULL; | |
752 | struct fsnotify_group *group; | |
753 | struct file *filp; | |
754 | struct path path; | |
755 | int ret, fput_needed; | |
756 | ||
757 | pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n", | |
758 | __func__, fanotify_fd, flags, dfd, pathname, mask); | |
759 | ||
760 | /* we only use the lower 32 bits as of right now. */ | |
761 | if (mask & ((__u64)0xffffffff << 32)) | |
762 | return -EINVAL; | |
763 | ||
764 | if (flags & ~FAN_ALL_MARK_FLAGS) | |
765 | return -EINVAL; | |
766 | switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { | |
767 | case FAN_MARK_ADD: | |
768 | case FAN_MARK_REMOVE: | |
769 | case FAN_MARK_FLUSH: | |
770 | break; | |
771 | default: | |
772 | return -EINVAL; | |
773 | } | |
774 | ||
775 | if (mask & FAN_ONDIR) { | |
776 | flags |= FAN_MARK_ONDIR; | |
777 | mask &= ~FAN_ONDIR; | |
778 | } | |
779 | ||
780 | #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS | |
781 | if (mask & ~(FAN_ALL_EVENTS | FAN_ALL_PERM_EVENTS | FAN_EVENT_ON_CHILD)) | |
782 | #else | |
783 | if (mask & ~(FAN_ALL_EVENTS | FAN_EVENT_ON_CHILD)) | |
784 | #endif | |
785 | return -EINVAL; | |
786 | ||
787 | filp = fget_light(fanotify_fd, &fput_needed); | |
788 | if (unlikely(!filp)) | |
789 | return -EBADF; | |
790 | ||
791 | /* verify that this is indeed an fanotify instance */ | |
792 | ret = -EINVAL; | |
793 | if (unlikely(filp->f_op != &fanotify_fops)) | |
794 | goto fput_and_out; | |
795 | group = filp->private_data; | |
796 | ||
797 | /* | |
798 | * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not | |
799 | * allowed to set permissions events. | |
800 | */ | |
801 | ret = -EINVAL; | |
802 | if (mask & FAN_ALL_PERM_EVENTS && | |
803 | group->priority == FS_PRIO_0) | |
804 | goto fput_and_out; | |
805 | ||
806 | ret = fanotify_find_path(dfd, pathname, &path, flags); | |
807 | if (ret) | |
808 | goto fput_and_out; | |
809 | ||
810 | /* inode held in place by reference to path; group by fget on fd */ | |
811 | if (!(flags & FAN_MARK_MOUNT)) | |
812 | inode = path.dentry->d_inode; | |
813 | else | |
814 | mnt = path.mnt; | |
815 | ||
816 | /* create/update an inode mark */ | |
817 | switch (flags & (FAN_MARK_ADD | FAN_MARK_REMOVE | FAN_MARK_FLUSH)) { | |
818 | case FAN_MARK_ADD: | |
819 | if (flags & FAN_MARK_MOUNT) | |
820 | ret = fanotify_add_vfsmount_mark(group, mnt, mask, flags); | |
821 | else | |
822 | ret = fanotify_add_inode_mark(group, inode, mask, flags); | |
823 | break; | |
824 | case FAN_MARK_REMOVE: | |
825 | if (flags & FAN_MARK_MOUNT) | |
826 | ret = fanotify_remove_vfsmount_mark(group, mnt, mask, flags); | |
827 | else | |
828 | ret = fanotify_remove_inode_mark(group, inode, mask, flags); | |
829 | break; | |
830 | case FAN_MARK_FLUSH: | |
831 | if (flags & FAN_MARK_MOUNT) | |
832 | fsnotify_clear_vfsmount_marks_by_group(group); | |
833 | else | |
834 | fsnotify_clear_inode_marks_by_group(group); | |
835 | break; | |
836 | default: | |
837 | ret = -EINVAL; | |
838 | } | |
839 | ||
840 | path_put(&path); | |
841 | fput_and_out: | |
842 | fput_light(filp, fput_needed); | |
843 | return ret; | |
844 | } | |
845 | ||
846 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
847 | asmlinkage long SyS_fanotify_mark(long fanotify_fd, long flags, __u64 mask, | |
848 | long dfd, long pathname) | |
849 | { | |
850 | return SYSC_fanotify_mark((int) fanotify_fd, (unsigned int) flags, | |
851 | mask, (int) dfd, | |
852 | (const char __user *) pathname); | |
853 | } | |
854 | SYSCALL_ALIAS(sys_fanotify_mark, SyS_fanotify_mark); | |
855 | #endif | |
856 | ||
857 | /* | |
858 | * fanotify_user_setup - Our initialization function. Note that we cannnot return | |
859 | * error because we have compiled-in VFS hooks. So an (unlikely) failure here | |
860 | * must result in panic(). | |
861 | */ | |
862 | static int __init fanotify_user_setup(void) | |
863 | { | |
864 | fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); | |
865 | fanotify_response_event_cache = KMEM_CACHE(fanotify_response_event, | |
866 | SLAB_PANIC); | |
867 | ||
868 | return 0; | |
869 | } | |
870 | device_initcall(fanotify_user_setup); |