1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Filesystem access notification for Linux
5 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
8 #ifndef __LINUX_FSNOTIFY_BACKEND_H
9 #define __LINUX_FSNOTIFY_BACKEND_H
13 #include <linux/idr.h> /* inotify uses this */
14 #include <linux/fs.h> /* struct inode */
15 #include <linux/list.h>
16 #include <linux/path.h> /* struct path */
17 #include <linux/spinlock.h>
18 #include <linux/types.h>
19 #include <linux/atomic.h>
20 #include <linux/user_namespace.h>
21 #include <linux/refcount.h>
24 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
25 * convert between them. dnotify only needs conversion at watch creation
26 * so no perf loss there. fanotify isn't defined yet, so it can use the
27 * wholes if it needs more events.
29 #define FS_ACCESS 0x00000001 /* File was accessed */
30 #define FS_MODIFY 0x00000002 /* File was modified */
31 #define FS_ATTRIB 0x00000004 /* Metadata changed */
32 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
33 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
34 #define FS_OPEN 0x00000020 /* File was opened */
35 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */
36 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */
37 #define FS_CREATE 0x00000100 /* Subfile was created */
38 #define FS_DELETE 0x00000200 /* Subfile was deleted */
39 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */
40 #define FS_MOVE_SELF 0x00000800 /* Self was moved */
41 #define FS_OPEN_EXEC 0x00001000 /* File was opened for exec */
43 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */
44 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
45 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
47 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
48 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
49 #define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */
51 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
52 /* This inode cares about things that happen to its children. Always set for
53 * dnotify and inotify. */
54 #define FS_EVENT_ON_CHILD 0x08000000
56 #define FS_DN_RENAME 0x10000000 /* file renamed */
57 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
58 #define FS_ISDIR 0x40000000 /* event occurred against dir */
59 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
61 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
64 * Directory entry modification events - reported only to directory
65 * where entry is modified and not to a watching parent.
66 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
67 * when a directory entry inside a child subdir changes.
69 #define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE)
71 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
75 * This is a list of all events that may get sent to a parent based on fs event
76 * happening to inodes inside that directory.
78 #define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \
79 FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
80 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
81 FS_OPEN | FS_OPEN_EXEC)
83 /* Events that can be reported to backends */
84 #define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
85 FS_EVENTS_POSS_ON_CHILD | \
86 FS_DELETE_SELF | FS_MOVE_SELF | FS_DN_RENAME | \
87 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED)
89 /* Extra flags that may be reported with event or control handling of events */
90 #define ALL_FSNOTIFY_FLAGS (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
91 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
93 #define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
95 struct fsnotify_group;
96 struct fsnotify_event;
98 struct fsnotify_event_private_data;
99 struct fsnotify_fname;
100 struct fsnotify_iter_info;
105 * Each group much define these ops. The fsnotify infrastructure will call
106 * these operations for each relevant group.
108 * handle_event - main call for a group to handle an fs event
109 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
110 * freeing_mark - called when a mark is being destroyed for some reason. The group
111 * MUST be holding a reference on each mark and that reference must be
112 * dropped in this function. inotify uses this function to send
113 * userspace messages that marks have been removed.
115 struct fsnotify_ops {
116 int (*handle_event)(struct fsnotify_group *group,
118 u32 mask, const void *data, int data_type,
119 const struct qstr *file_name, u32 cookie,
120 struct fsnotify_iter_info *iter_info);
121 void (*free_group_priv)(struct fsnotify_group *group);
122 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
123 void (*free_event)(struct fsnotify_event *event);
124 /* called on final put+free to free memory */
125 void (*free_mark)(struct fsnotify_mark *mark);
129 * all of the information about the original object we want to now send to
130 * a group. If you want to carry more info from the accessing task to the
131 * listener this structure is where you need to be adding fields.
133 struct fsnotify_event {
134 struct list_head list;
135 /* inode may ONLY be dereferenced during handle_event(). */
136 struct inode *inode; /* either the inode the event happened to or its parent */
140 * A group is a "thing" that wants to receive notification about filesystem
141 * events. The mask holds the subset of event types this group cares about.
142 * refcnt on a group is up to the implementor and at any moment if it goes 0
143 * everything will be cleaned up.
145 struct fsnotify_group {
146 const struct fsnotify_ops *ops; /* how this group handles things */
149 * How the refcnt is used is up to each group. When the refcnt hits 0
150 * fsnotify will clean up all of the resources associated with this group.
151 * As an example, the dnotify group will always have a refcnt=1 and that
152 * will never change. Inotify, on the other hand, has a group per
153 * inotify_init() and the refcnt will hit 0 only when that fd has been
156 refcount_t refcnt; /* things with interest in this group */
158 /* needed to send notification to userspace */
159 spinlock_t notification_lock; /* protect the notification_list */
160 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
161 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
162 unsigned int q_len; /* events on the queue */
163 unsigned int max_events; /* maximum events allowed on the list */
165 * Valid fsnotify group priorities. Events are send in order from highest
166 * priority to lowest priority. We default to the lowest priority.
168 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
169 #define FS_PRIO_1 1 /* fanotify content based access control */
170 #define FS_PRIO_2 2 /* fanotify pre-content access */
171 unsigned int priority;
172 bool shutdown; /* group is being shut down, don't queue more events */
174 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
175 struct mutex mark_mutex; /* protect marks_list */
176 atomic_t num_marks; /* 1 for each mark and 1 for not being
177 * past the point of no return when freeing
179 atomic_t user_waits; /* Number of tasks waiting for user
181 struct list_head marks_list; /* all inode marks for this group */
183 struct fasync_struct *fsn_fa; /* async notification */
185 struct fsnotify_event *overflow_event; /* Event we queue when the
186 * notification list is too
189 struct mem_cgroup *memcg; /* memcg to charge allocations */
191 /* groups can define private fields here or use the void *private */
194 #ifdef CONFIG_INOTIFY_USER
195 struct inotify_group_private_data {
198 struct ucounts *ucounts;
201 #ifdef CONFIG_FANOTIFY
202 struct fanotify_group_private_data {
203 /* allows a group to block waiting for a userspace response */
204 struct list_head access_list;
205 wait_queue_head_t access_waitq;
206 int flags; /* flags from fanotify_init() */
207 int f_flags; /* event_f_flags from fanotify_init() */
208 unsigned int max_marks;
209 struct user_struct *user;
211 #endif /* CONFIG_FANOTIFY */
215 /* When calling fsnotify tell it if the data is a path or inode */
216 enum fsnotify_data_type {
219 FSNOTIFY_EVENT_INODE,
222 static inline const struct inode *fsnotify_data_inode(const void *data,
226 case FSNOTIFY_EVENT_INODE:
228 case FSNOTIFY_EVENT_PATH:
229 return d_inode(((const struct path *)data)->dentry);
235 static inline const struct path *fsnotify_data_path(const void *data,
239 case FSNOTIFY_EVENT_PATH:
246 enum fsnotify_obj_type {
247 FSNOTIFY_OBJ_TYPE_INODE,
248 FSNOTIFY_OBJ_TYPE_VFSMOUNT,
249 FSNOTIFY_OBJ_TYPE_SB,
250 FSNOTIFY_OBJ_TYPE_COUNT,
251 FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
254 #define FSNOTIFY_OBJ_TYPE_INODE_FL (1U << FSNOTIFY_OBJ_TYPE_INODE)
255 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL (1U << FSNOTIFY_OBJ_TYPE_VFSMOUNT)
256 #define FSNOTIFY_OBJ_TYPE_SB_FL (1U << FSNOTIFY_OBJ_TYPE_SB)
257 #define FSNOTIFY_OBJ_ALL_TYPES_MASK ((1U << FSNOTIFY_OBJ_TYPE_COUNT) - 1)
259 static inline bool fsnotify_valid_obj_type(unsigned int type)
261 return (type < FSNOTIFY_OBJ_TYPE_COUNT);
264 struct fsnotify_iter_info {
265 struct fsnotify_mark *marks[FSNOTIFY_OBJ_TYPE_COUNT];
266 unsigned int report_mask;
270 static inline bool fsnotify_iter_should_report_type(
271 struct fsnotify_iter_info *iter_info, int type)
273 return (iter_info->report_mask & (1U << type));
276 static inline void fsnotify_iter_set_report_type(
277 struct fsnotify_iter_info *iter_info, int type)
279 iter_info->report_mask |= (1U << type);
282 static inline void fsnotify_iter_set_report_type_mark(
283 struct fsnotify_iter_info *iter_info, int type,
284 struct fsnotify_mark *mark)
286 iter_info->marks[type] = mark;
287 iter_info->report_mask |= (1U << type);
290 #define FSNOTIFY_ITER_FUNCS(name, NAME) \
291 static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
292 struct fsnotify_iter_info *iter_info) \
294 return (iter_info->report_mask & FSNOTIFY_OBJ_TYPE_##NAME##_FL) ? \
295 iter_info->marks[FSNOTIFY_OBJ_TYPE_##NAME] : NULL; \
298 FSNOTIFY_ITER_FUNCS(inode, INODE)
299 FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
300 FSNOTIFY_ITER_FUNCS(sb, SB)
302 #define fsnotify_foreach_obj_type(type) \
303 for (type = 0; type < FSNOTIFY_OBJ_TYPE_COUNT; type++)
306 * fsnotify_connp_t is what we embed in objects which connector can be attached
307 * to. fsnotify_connp_t * is how we refer from connector back to object.
309 struct fsnotify_mark_connector;
310 typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t;
313 * Inode/vfsmount/sb point to this structure which tracks all marks attached to
314 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
315 * structure. We destroy this structure when there are no more marks attached
316 * to it. The structure is protected by fsnotify_mark_srcu.
318 struct fsnotify_mark_connector {
320 unsigned short type; /* Type of object [lock] */
321 #define FSNOTIFY_CONN_FLAG_HAS_FSID 0x01
322 unsigned short flags; /* flags [lock] */
323 __kernel_fsid_t fsid; /* fsid of filesystem containing object */
325 /* Object pointer [lock] */
326 fsnotify_connp_t *obj;
327 /* Used listing heads to free after srcu period expires */
328 struct fsnotify_mark_connector *destroy_next;
330 struct hlist_head list;
334 * A mark is simply an object attached to an in core inode which allows an
335 * fsnotify listener to indicate they are either no longer interested in events
336 * of a type matching mask or only interested in those events.
338 * These are flushed when an inode is evicted from core and may be flushed
339 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
340 * users (such as dnotify) will flush these when the open fd is closed and not
341 * at inode eviction or modification.
343 * Text in brackets is showing the lock(s) protecting modifications of a
344 * particular entry. obj_lock means either inode->i_lock or
345 * mnt->mnt_root->d_lock depending on the mark type.
347 struct fsnotify_mark {
348 /* Mask this mark is for [mark->lock, group->mark_mutex] */
350 /* We hold one for presence in g_list. Also one ref for each 'thing'
351 * in kernel that found and may be using this mark. */
353 /* Group this mark is for. Set on mark creation, stable until last ref
355 struct fsnotify_group *group;
356 /* List of marks by group->marks_list. Also reused for queueing
357 * mark into destroy_list when it's waiting for the end of SRCU period
358 * before it can be freed. [group->mark_mutex] */
359 struct list_head g_list;
360 /* Protects inode / mnt pointers, flags, masks */
362 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
363 struct hlist_node obj_list;
364 /* Head of list of marks for an object [mark ref] */
365 struct fsnotify_mark_connector *connector;
366 /* Events types to ignore [mark->lock, group->mark_mutex] */
368 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01
369 #define FSNOTIFY_MARK_FLAG_ALIVE 0x02
370 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x04
371 unsigned int flags; /* flags [mark->lock] */
374 #ifdef CONFIG_FSNOTIFY
376 /* called from the vfs helpers */
378 /* main fsnotify call to send events */
379 extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
380 const struct qstr *name, u32 cookie);
381 extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
382 extern void __fsnotify_inode_delete(struct inode *inode);
383 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
384 extern void fsnotify_sb_delete(struct super_block *sb);
385 extern u32 fsnotify_get_cookie(void);
387 static inline int fsnotify_inode_watches_children(struct inode *inode)
389 /* FS_EVENT_ON_CHILD is set if the inode may care */
390 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
392 /* this inode might care about child events, does it care about the
393 * specific set of events that can happen on a child? */
394 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
398 * Update the dentry with a flag indicating the interest of its parent to receive
399 * filesystem events when those events happens to this dentry->d_inode.
401 static inline void fsnotify_update_flags(struct dentry *dentry)
403 assert_spin_locked(&dentry->d_lock);
406 * Serialisation of setting PARENT_WATCHED on the dentries is provided
407 * by d_lock. If inotify_inode_watched changes after we have taken
408 * d_lock, the following __fsnotify_update_child_dentry_flags call will
409 * find our entry, so it will spin until we complete here, and update
410 * us with the new state.
412 if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
413 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
415 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
418 /* called from fsnotify listeners, such as fanotify or dnotify */
420 /* create a new group */
421 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
422 /* get reference to a group */
423 extern void fsnotify_get_group(struct fsnotify_group *group);
424 /* drop reference on a group from fsnotify_alloc_group */
425 extern void fsnotify_put_group(struct fsnotify_group *group);
426 /* group destruction begins, stop queuing new events */
427 extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
429 extern void fsnotify_destroy_group(struct fsnotify_group *group);
430 /* fasync handler function */
431 extern int fsnotify_fasync(int fd, struct file *file, int on);
432 /* Free event from memory */
433 extern void fsnotify_destroy_event(struct fsnotify_group *group,
434 struct fsnotify_event *event);
435 /* attach the event to the group notification queue */
436 extern int fsnotify_add_event(struct fsnotify_group *group,
437 struct fsnotify_event *event,
438 int (*merge)(struct list_head *,
439 struct fsnotify_event *));
440 /* Queue overflow event to a notification group */
441 static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
443 fsnotify_add_event(group, group->overflow_event, NULL);
446 /* true if the group notification queue is empty */
447 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
448 /* return, but do not dequeue the first event on the notification queue */
449 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
450 /* return AND dequeue the first event on the notification queue */
451 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
452 /* Remove event queued in the notification list */
453 extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
454 struct fsnotify_event *event);
456 /* functions used to manipulate the marks attached to inodes */
458 /* Get mask of events for a list of marks */
459 extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
460 /* Calculate mask of events for a list of marks */
461 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
462 extern void fsnotify_init_mark(struct fsnotify_mark *mark,
463 struct fsnotify_group *group);
464 /* Find mark belonging to given group in the list of marks */
465 extern struct fsnotify_mark *fsnotify_find_mark(fsnotify_connp_t *connp,
466 struct fsnotify_group *group);
467 /* Get cached fsid of filesystem containing object */
468 extern int fsnotify_get_conn_fsid(const struct fsnotify_mark_connector *conn,
469 __kernel_fsid_t *fsid);
470 /* attach the mark to the object */
471 extern int fsnotify_add_mark(struct fsnotify_mark *mark,
472 fsnotify_connp_t *connp, unsigned int type,
473 int allow_dups, __kernel_fsid_t *fsid);
474 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark,
475 fsnotify_connp_t *connp,
476 unsigned int type, int allow_dups,
477 __kernel_fsid_t *fsid);
479 /* attach the mark to the inode */
480 static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
484 return fsnotify_add_mark(mark, &inode->i_fsnotify_marks,
485 FSNOTIFY_OBJ_TYPE_INODE, allow_dups, NULL);
487 static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
491 return fsnotify_add_mark_locked(mark, &inode->i_fsnotify_marks,
492 FSNOTIFY_OBJ_TYPE_INODE, allow_dups,
496 /* given a group and a mark, flag mark to be freed when all references are dropped */
497 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
498 struct fsnotify_group *group);
499 /* detach mark from inode / mount list, group list, drop inode reference */
500 extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
502 extern void fsnotify_free_mark(struct fsnotify_mark *mark);
503 /* Wait until all marks queued for destruction are destroyed */
504 extern void fsnotify_wait_marks_destroyed(void);
505 /* run all the marks in a group, and clear all of the marks attached to given object type */
506 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group, unsigned int type);
507 /* run all the marks in a group, and clear all of the vfsmount marks */
508 static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
510 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL);
512 /* run all the marks in a group, and clear all of the inode marks */
513 static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
515 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE_FL);
517 /* run all the marks in a group, and clear all of the sn marks */
518 static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group)
520 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_SB_FL);
522 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
523 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
524 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
525 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
527 static inline void fsnotify_init_event(struct fsnotify_event *event,
530 INIT_LIST_HEAD(&event->list);
531 event->inode = inode;
536 static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
537 const struct qstr *name, u32 cookie)
542 static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask)
547 static inline void __fsnotify_inode_delete(struct inode *inode)
550 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
553 static inline void fsnotify_sb_delete(struct super_block *sb)
556 static inline void fsnotify_update_flags(struct dentry *dentry)
559 static inline u32 fsnotify_get_cookie(void)
564 static inline void fsnotify_unmount_inodes(struct super_block *sb)
567 #endif /* CONFIG_FSNOTIFY */
569 #endif /* __KERNEL __ */
571 #endif /* __LINUX_FSNOTIFY_BACKEND_H */