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 */
42 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */
43 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
44 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
46 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
47 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
49 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
50 #define FS_ISDIR 0x40000000 /* event occurred against dir */
51 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
53 #define FS_DN_RENAME 0x10000000 /* file renamed */
54 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
56 /* This inode cares about things that happen to its children. Always set for
57 * dnotify and inotify. */
58 #define FS_EVENT_ON_CHILD 0x08000000
60 /* This is a list of all events that may get sent to a parernt based on fs event
61 * happening to inodes inside that directory */
62 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
63 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
64 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
65 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
67 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
69 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
71 /* Events that can be reported to backends */
72 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
73 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
74 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
75 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
76 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
77 FS_OPEN_PERM | FS_ACCESS_PERM | FS_DN_RENAME)
79 /* Extra flags that may be reported with event or control handling of events */
80 #define ALL_FSNOTIFY_FLAGS (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
81 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
83 #define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
85 struct fsnotify_group
;
86 struct fsnotify_event
;
88 struct fsnotify_event_private_data
;
89 struct fsnotify_fname
;
90 struct fsnotify_iter_info
;
93 * Each group much define these ops. The fsnotify infrastructure will call
94 * these operations for each relevant group.
96 * handle_event - main call for a group to handle an fs event
97 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
98 * freeing_mark - called when a mark is being destroyed for some reason. The group
99 * MUST be holding a reference on each mark and that reference must be
100 * dropped in this function. inotify uses this function to send
101 * userspace messages that marks have been removed.
103 struct fsnotify_ops
{
104 int (*handle_event
)(struct fsnotify_group
*group
,
106 struct fsnotify_mark
*inode_mark
,
107 struct fsnotify_mark
*vfsmount_mark
,
108 u32 mask
, const void *data
, int data_type
,
109 const unsigned char *file_name
, u32 cookie
,
110 struct fsnotify_iter_info
*iter_info
);
111 void (*free_group_priv
)(struct fsnotify_group
*group
);
112 void (*freeing_mark
)(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
);
113 void (*free_event
)(struct fsnotify_event
*event
);
114 /* called on final put+free to free memory */
115 void (*free_mark
)(struct fsnotify_mark
*mark
);
119 * all of the information about the original object we want to now send to
120 * a group. If you want to carry more info from the accessing task to the
121 * listener this structure is where you need to be adding fields.
123 struct fsnotify_event
{
124 struct list_head list
;
125 /* inode may ONLY be dereferenced during handle_event(). */
126 struct inode
*inode
; /* either the inode the event happened to or its parent */
127 u32 mask
; /* the type of access, bitwise OR for FS_* event types */
131 * A group is a "thing" that wants to receive notification about filesystem
132 * events. The mask holds the subset of event types this group cares about.
133 * refcnt on a group is up to the implementor and at any moment if it goes 0
134 * everything will be cleaned up.
136 struct fsnotify_group
{
138 * How the refcnt is used is up to each group. When the refcnt hits 0
139 * fsnotify will clean up all of the resources associated with this group.
140 * As an example, the dnotify group will always have a refcnt=1 and that
141 * will never change. Inotify, on the other hand, has a group per
142 * inotify_init() and the refcnt will hit 0 only when that fd has been
145 refcount_t refcnt
; /* things with interest in this group */
147 const struct fsnotify_ops
*ops
; /* how this group handles things */
149 /* needed to send notification to userspace */
150 spinlock_t notification_lock
; /* protect the notification_list */
151 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
152 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
153 unsigned int q_len
; /* events on the queue */
154 unsigned int max_events
; /* maximum events allowed on the list */
156 * Valid fsnotify group priorities. Events are send in order from highest
157 * priority to lowest priority. We default to the lowest priority.
159 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
160 #define FS_PRIO_1 1 /* fanotify content based access control */
161 #define FS_PRIO_2 2 /* fanotify pre-content access */
162 unsigned int priority
;
163 bool shutdown
; /* group is being shut down, don't queue more events */
165 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
166 struct mutex mark_mutex
; /* protect marks_list */
167 atomic_t num_marks
; /* 1 for each mark and 1 for not being
168 * past the point of no return when freeing
170 struct list_head marks_list
; /* all inode marks for this group */
172 struct fasync_struct
*fsn_fa
; /* async notification */
174 struct fsnotify_event
*overflow_event
; /* Event we queue when the
175 * notification list is too
177 atomic_t user_waits
; /* Number of tasks waiting for user
180 /* groups can define private fields here or use the void *private */
183 #ifdef CONFIG_INOTIFY_USER
184 struct inotify_group_private_data
{
187 struct ucounts
*ucounts
;
190 #ifdef CONFIG_FANOTIFY
191 struct fanotify_group_private_data
{
192 /* allows a group to block waiting for a userspace response */
193 struct list_head access_list
;
194 wait_queue_head_t access_waitq
;
196 unsigned int max_marks
;
197 struct user_struct
*user
;
200 #endif /* CONFIG_FANOTIFY */
204 /* when calling fsnotify tell it if the data is a path or inode */
205 #define FSNOTIFY_EVENT_NONE 0
206 #define FSNOTIFY_EVENT_PATH 1
207 #define FSNOTIFY_EVENT_INODE 2
210 * Inode / vfsmount point to this structure which tracks all marks attached to
211 * the inode / vfsmount. The reference to inode / vfsmount is held by this
212 * structure. We destroy this structure when there are no more marks attached
213 * to it. The structure is protected by fsnotify_mark_srcu.
215 struct fsnotify_mark_connector
{
217 #define FSNOTIFY_OBJ_TYPE_INODE 0x01
218 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT 0x02
219 #define FSNOTIFY_OBJ_ALL_TYPES (FSNOTIFY_OBJ_TYPE_INODE | \
220 FSNOTIFY_OBJ_TYPE_VFSMOUNT)
221 unsigned int flags
; /* Type of object [lock] */
222 union { /* Object pointer [lock] */
224 struct vfsmount
*mnt
;
225 /* Used listing heads to free after srcu period expires */
226 struct fsnotify_mark_connector
*destroy_next
;
228 struct hlist_head list
;
232 * A mark is simply an object attached to an in core inode which allows an
233 * fsnotify listener to indicate they are either no longer interested in events
234 * of a type matching mask or only interested in those events.
236 * These are flushed when an inode is evicted from core and may be flushed
237 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
238 * users (such as dnotify) will flush these when the open fd is closed and not
239 * at inode eviction or modification.
241 * Text in brackets is showing the lock(s) protecting modifications of a
242 * particular entry. obj_lock means either inode->i_lock or
243 * mnt->mnt_root->d_lock depending on the mark type.
245 struct fsnotify_mark
{
246 /* Mask this mark is for [mark->lock, group->mark_mutex] */
248 /* We hold one for presence in g_list. Also one ref for each 'thing'
249 * in kernel that found and may be using this mark. */
251 /* Group this mark is for. Set on mark creation, stable until last ref
253 struct fsnotify_group
*group
;
254 /* List of marks by group->i_fsnotify_marks. Also reused for queueing
255 * mark into destroy_list when it's waiting for the end of SRCU period
256 * before it can be freed. [group->mark_mutex] */
257 struct list_head g_list
;
258 /* Protects inode / mnt pointers, flags, masks */
260 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
261 struct hlist_node obj_list
;
262 /* Head of list of marks for an object [mark ref] */
263 struct fsnotify_mark_connector
*connector
;
264 /* Events types to ignore [mark->lock, group->mark_mutex] */
266 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01
267 #define FSNOTIFY_MARK_FLAG_ALIVE 0x02
268 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x04
269 unsigned int flags
; /* flags [mark->lock] */
272 #ifdef CONFIG_FSNOTIFY
274 /* called from the vfs helpers */
276 /* main fsnotify call to send events */
277 extern int fsnotify(struct inode
*to_tell
, __u32 mask
, const void *data
, int data_is
,
278 const unsigned char *name
, u32 cookie
);
279 extern int __fsnotify_parent(const struct path
*path
, struct dentry
*dentry
, __u32 mask
);
280 extern void __fsnotify_inode_delete(struct inode
*inode
);
281 extern void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
);
282 extern u32
fsnotify_get_cookie(void);
284 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
286 /* FS_EVENT_ON_CHILD is set if the inode may care */
287 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
289 /* this inode might care about child events, does it care about the
290 * specific set of events that can happen on a child? */
291 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
295 * Update the dentry with a flag indicating the interest of its parent to receive
296 * filesystem events when those events happens to this dentry->d_inode.
298 static inline void fsnotify_update_flags(struct dentry
*dentry
)
300 assert_spin_locked(&dentry
->d_lock
);
303 * Serialisation of setting PARENT_WATCHED on the dentries is provided
304 * by d_lock. If inotify_inode_watched changes after we have taken
305 * d_lock, the following __fsnotify_update_child_dentry_flags call will
306 * find our entry, so it will spin until we complete here, and update
307 * us with the new state.
309 if (fsnotify_inode_watches_children(dentry
->d_parent
->d_inode
))
310 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
312 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
315 /* called from fsnotify listeners, such as fanotify or dnotify */
317 /* create a new group */
318 extern struct fsnotify_group
*fsnotify_alloc_group(const struct fsnotify_ops
*ops
);
319 /* get reference to a group */
320 extern void fsnotify_get_group(struct fsnotify_group
*group
);
321 /* drop reference on a group from fsnotify_alloc_group */
322 extern void fsnotify_put_group(struct fsnotify_group
*group
);
323 /* group destruction begins, stop queuing new events */
324 extern void fsnotify_group_stop_queueing(struct fsnotify_group
*group
);
326 extern void fsnotify_destroy_group(struct fsnotify_group
*group
);
327 /* fasync handler function */
328 extern int fsnotify_fasync(int fd
, struct file
*file
, int on
);
329 /* Free event from memory */
330 extern void fsnotify_destroy_event(struct fsnotify_group
*group
,
331 struct fsnotify_event
*event
);
332 /* attach the event to the group notification queue */
333 extern int fsnotify_add_event(struct fsnotify_group
*group
,
334 struct fsnotify_event
*event
,
335 int (*merge
)(struct list_head
*,
336 struct fsnotify_event
*));
337 /* true if the group notification queue is empty */
338 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group
*group
);
339 /* return, but do not dequeue the first event on the notification queue */
340 extern struct fsnotify_event
*fsnotify_peek_first_event(struct fsnotify_group
*group
);
341 /* return AND dequeue the first event on the notification queue */
342 extern struct fsnotify_event
*fsnotify_remove_first_event(struct fsnotify_group
*group
);
344 /* functions used to manipulate the marks attached to inodes */
346 /* Calculate mask of events for a list of marks */
347 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector
*conn
);
348 extern void fsnotify_init_mark(struct fsnotify_mark
*mark
,
349 struct fsnotify_group
*group
);
350 /* Find mark belonging to given group in the list of marks */
351 extern struct fsnotify_mark
*fsnotify_find_mark(
352 struct fsnotify_mark_connector __rcu
**connp
,
353 struct fsnotify_group
*group
);
354 /* attach the mark to the inode or vfsmount */
355 extern int fsnotify_add_mark(struct fsnotify_mark
*mark
, struct inode
*inode
,
356 struct vfsmount
*mnt
, int allow_dups
);
357 extern int fsnotify_add_mark_locked(struct fsnotify_mark
*mark
,
358 struct inode
*inode
, struct vfsmount
*mnt
, int allow_dups
);
359 /* given a group and a mark, flag mark to be freed when all references are dropped */
360 extern void fsnotify_destroy_mark(struct fsnotify_mark
*mark
,
361 struct fsnotify_group
*group
);
362 /* detach mark from inode / mount list, group list, drop inode reference */
363 extern void fsnotify_detach_mark(struct fsnotify_mark
*mark
);
365 extern void fsnotify_free_mark(struct fsnotify_mark
*mark
);
366 /* run all the marks in a group, and clear all of the marks attached to given object type */
367 extern void fsnotify_clear_marks_by_group(struct fsnotify_group
*group
, unsigned int type
);
368 /* run all the marks in a group, and clear all of the vfsmount marks */
369 static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group
*group
)
371 fsnotify_clear_marks_by_group(group
, FSNOTIFY_OBJ_TYPE_VFSMOUNT
);
373 /* run all the marks in a group, and clear all of the inode marks */
374 static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group
*group
)
376 fsnotify_clear_marks_by_group(group
, FSNOTIFY_OBJ_TYPE_INODE
);
378 extern void fsnotify_get_mark(struct fsnotify_mark
*mark
);
379 extern void fsnotify_put_mark(struct fsnotify_mark
*mark
);
380 extern void fsnotify_unmount_inodes(struct super_block
*sb
);
381 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info
*iter_info
);
382 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info
*iter_info
);
384 /* put here because inotify does some weird stuff when destroying watches */
385 extern void fsnotify_init_event(struct fsnotify_event
*event
,
386 struct inode
*to_tell
, u32 mask
);
390 static inline int fsnotify(struct inode
*to_tell
, __u32 mask
, const void *data
, int data_is
,
391 const unsigned char *name
, u32 cookie
)
396 static inline int __fsnotify_parent(const struct path
*path
, struct dentry
*dentry
, __u32 mask
)
401 static inline void __fsnotify_inode_delete(struct inode
*inode
)
404 static inline void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
)
407 static inline void fsnotify_update_flags(struct dentry
*dentry
)
410 static inline u32
fsnotify_get_cookie(void)
415 static inline void fsnotify_unmount_inodes(struct super_block
*sb
)
418 #endif /* CONFIG_FSNOTIFY */
420 #endif /* __KERNEL __ */
422 #endif /* __LINUX_FSNOTIFY_BACKEND_H */