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 #define FS_ISDIR 0x40000000 /* event occurred against dir */
53 #define FS_IN_ONESHOT 0x80000000 /* only send event once */
55 #define FS_DN_RENAME 0x10000000 /* file renamed */
56 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
58 /* This inode cares about things that happen to its children. Always set for
59 * dnotify and inotify. */
60 #define FS_EVENT_ON_CHILD 0x08000000
62 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
65 * Directory entry modification events - reported only to directory
66 * where entry is modified and not to a watching parent.
67 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
68 * when a directory entry inside a child subdir changes.
70 #define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE)
72 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
76 * This is a list of all events that may get sent to a parent based on fs event
77 * happening to inodes inside that directory.
79 #define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \
80 FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
81 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
82 FS_OPEN | FS_OPEN_EXEC)
84 /* Events that can be reported to backends */
85 #define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
86 FS_EVENTS_POSS_ON_CHILD | \
87 FS_DELETE_SELF | FS_MOVE_SELF | FS_DN_RENAME | \
88 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED)
90 /* Extra flags that may be reported with event or control handling of events */
91 #define ALL_FSNOTIFY_FLAGS (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
92 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
94 #define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
96 struct fsnotify_group
;
97 struct fsnotify_event
;
99 struct fsnotify_event_private_data
;
100 struct fsnotify_fname
;
101 struct fsnotify_iter_info
;
106 * Each group much define these ops. The fsnotify infrastructure will call
107 * these operations for each relevant group.
109 * handle_event - main call for a group to handle an fs event
110 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
111 * freeing_mark - called when a mark is being destroyed for some reason. The group
112 * MUST be holding a reference on each mark and that reference must be
113 * dropped in this function. inotify uses this function to send
114 * userspace messages that marks have been removed.
116 struct fsnotify_ops
{
117 int (*handle_event
)(struct fsnotify_group
*group
,
119 u32 mask
, const void *data
, int data_type
,
120 const struct qstr
*file_name
, u32 cookie
,
121 struct fsnotify_iter_info
*iter_info
);
122 void (*free_group_priv
)(struct fsnotify_group
*group
);
123 void (*freeing_mark
)(struct fsnotify_mark
*mark
, struct fsnotify_group
*group
);
124 void (*free_event
)(struct fsnotify_event
*event
);
125 /* called on final put+free to free memory */
126 void (*free_mark
)(struct fsnotify_mark
*mark
);
130 * all of the information about the original object we want to now send to
131 * a group. If you want to carry more info from the accessing task to the
132 * listener this structure is where you need to be adding fields.
134 struct fsnotify_event
{
135 struct list_head list
;
136 /* inode may ONLY be dereferenced during handle_event(). */
137 struct inode
*inode
; /* either the inode the event happened to or its parent */
141 * A group is a "thing" that wants to receive notification about filesystem
142 * events. The mask holds the subset of event types this group cares about.
143 * refcnt on a group is up to the implementor and at any moment if it goes 0
144 * everything will be cleaned up.
146 struct fsnotify_group
{
147 const struct fsnotify_ops
*ops
; /* how this group handles things */
150 * How the refcnt is used is up to each group. When the refcnt hits 0
151 * fsnotify will clean up all of the resources associated with this group.
152 * As an example, the dnotify group will always have a refcnt=1 and that
153 * will never change. Inotify, on the other hand, has a group per
154 * inotify_init() and the refcnt will hit 0 only when that fd has been
157 refcount_t refcnt
; /* things with interest in this group */
159 /* needed to send notification to userspace */
160 spinlock_t notification_lock
; /* protect the notification_list */
161 struct list_head notification_list
; /* list of event_holder this group needs to send to userspace */
162 wait_queue_head_t notification_waitq
; /* read() on the notification file blocks on this waitq */
163 unsigned int q_len
; /* events on the queue */
164 unsigned int max_events
; /* maximum events allowed on the list */
166 * Valid fsnotify group priorities. Events are send in order from highest
167 * priority to lowest priority. We default to the lowest priority.
169 #define FS_PRIO_0 0 /* normal notifiers, no permissions */
170 #define FS_PRIO_1 1 /* fanotify content based access control */
171 #define FS_PRIO_2 2 /* fanotify pre-content access */
172 unsigned int priority
;
173 bool shutdown
; /* group is being shut down, don't queue more events */
175 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
176 struct mutex mark_mutex
; /* protect marks_list */
177 atomic_t num_marks
; /* 1 for each mark and 1 for not being
178 * past the point of no return when freeing
180 atomic_t user_waits
; /* Number of tasks waiting for user
182 struct list_head marks_list
; /* all inode marks for this group */
184 struct fasync_struct
*fsn_fa
; /* async notification */
186 struct fsnotify_event
*overflow_event
; /* Event we queue when the
187 * notification list is too
190 struct mem_cgroup
*memcg
; /* memcg to charge allocations */
192 /* groups can define private fields here or use the void *private */
195 #ifdef CONFIG_INOTIFY_USER
196 struct inotify_group_private_data
{
199 struct ucounts
*ucounts
;
202 #ifdef CONFIG_FANOTIFY
203 struct fanotify_group_private_data
{
204 /* allows a group to block waiting for a userspace response */
205 struct list_head access_list
;
206 wait_queue_head_t access_waitq
;
207 int flags
; /* flags from fanotify_init() */
208 int f_flags
; /* event_f_flags from fanotify_init() */
209 unsigned int max_marks
;
210 struct user_struct
*user
;
212 #endif /* CONFIG_FANOTIFY */
216 /* when calling fsnotify tell it if the data is a path or inode */
217 #define FSNOTIFY_EVENT_NONE 0
218 #define FSNOTIFY_EVENT_PATH 1
219 #define FSNOTIFY_EVENT_INODE 2
221 enum fsnotify_obj_type
{
222 FSNOTIFY_OBJ_TYPE_INODE
,
223 FSNOTIFY_OBJ_TYPE_VFSMOUNT
,
224 FSNOTIFY_OBJ_TYPE_SB
,
225 FSNOTIFY_OBJ_TYPE_COUNT
,
226 FSNOTIFY_OBJ_TYPE_DETACHED
= FSNOTIFY_OBJ_TYPE_COUNT
229 #define FSNOTIFY_OBJ_TYPE_INODE_FL (1U << FSNOTIFY_OBJ_TYPE_INODE)
230 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL (1U << FSNOTIFY_OBJ_TYPE_VFSMOUNT)
231 #define FSNOTIFY_OBJ_TYPE_SB_FL (1U << FSNOTIFY_OBJ_TYPE_SB)
232 #define FSNOTIFY_OBJ_ALL_TYPES_MASK ((1U << FSNOTIFY_OBJ_TYPE_COUNT) - 1)
234 static inline bool fsnotify_valid_obj_type(unsigned int type
)
236 return (type
< FSNOTIFY_OBJ_TYPE_COUNT
);
239 struct fsnotify_iter_info
{
240 struct fsnotify_mark
*marks
[FSNOTIFY_OBJ_TYPE_COUNT
];
241 unsigned int report_mask
;
245 static inline bool fsnotify_iter_should_report_type(
246 struct fsnotify_iter_info
*iter_info
, int type
)
248 return (iter_info
->report_mask
& (1U << type
));
251 static inline void fsnotify_iter_set_report_type(
252 struct fsnotify_iter_info
*iter_info
, int type
)
254 iter_info
->report_mask
|= (1U << type
);
257 static inline void fsnotify_iter_set_report_type_mark(
258 struct fsnotify_iter_info
*iter_info
, int type
,
259 struct fsnotify_mark
*mark
)
261 iter_info
->marks
[type
] = mark
;
262 iter_info
->report_mask
|= (1U << type
);
265 #define FSNOTIFY_ITER_FUNCS(name, NAME) \
266 static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
267 struct fsnotify_iter_info *iter_info) \
269 return (iter_info->report_mask & FSNOTIFY_OBJ_TYPE_##NAME##_FL) ? \
270 iter_info->marks[FSNOTIFY_OBJ_TYPE_##NAME] : NULL; \
273 FSNOTIFY_ITER_FUNCS(inode
, INODE
)
274 FSNOTIFY_ITER_FUNCS(vfsmount
, VFSMOUNT
)
275 FSNOTIFY_ITER_FUNCS(sb
, SB
)
277 #define fsnotify_foreach_obj_type(type) \
278 for (type = 0; type < FSNOTIFY_OBJ_TYPE_COUNT; type++)
281 * fsnotify_connp_t is what we embed in objects which connector can be attached
282 * to. fsnotify_connp_t * is how we refer from connector back to object.
284 struct fsnotify_mark_connector
;
285 typedef struct fsnotify_mark_connector __rcu
*fsnotify_connp_t
;
288 * Inode/vfsmount/sb point to this structure which tracks all marks attached to
289 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
290 * structure. We destroy this structure when there are no more marks attached
291 * to it. The structure is protected by fsnotify_mark_srcu.
293 struct fsnotify_mark_connector
{
295 unsigned short type
; /* Type of object [lock] */
296 #define FSNOTIFY_CONN_FLAG_HAS_FSID 0x01
297 unsigned short flags
; /* flags [lock] */
298 __kernel_fsid_t fsid
; /* fsid of filesystem containing object */
300 /* Object pointer [lock] */
301 fsnotify_connp_t
*obj
;
302 /* Used listing heads to free after srcu period expires */
303 struct fsnotify_mark_connector
*destroy_next
;
305 struct hlist_head list
;
309 * A mark is simply an object attached to an in core inode which allows an
310 * fsnotify listener to indicate they are either no longer interested in events
311 * of a type matching mask or only interested in those events.
313 * These are flushed when an inode is evicted from core and may be flushed
314 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
315 * users (such as dnotify) will flush these when the open fd is closed and not
316 * at inode eviction or modification.
318 * Text in brackets is showing the lock(s) protecting modifications of a
319 * particular entry. obj_lock means either inode->i_lock or
320 * mnt->mnt_root->d_lock depending on the mark type.
322 struct fsnotify_mark
{
323 /* Mask this mark is for [mark->lock, group->mark_mutex] */
325 /* We hold one for presence in g_list. Also one ref for each 'thing'
326 * in kernel that found and may be using this mark. */
328 /* Group this mark is for. Set on mark creation, stable until last ref
330 struct fsnotify_group
*group
;
331 /* List of marks by group->marks_list. Also reused for queueing
332 * mark into destroy_list when it's waiting for the end of SRCU period
333 * before it can be freed. [group->mark_mutex] */
334 struct list_head g_list
;
335 /* Protects inode / mnt pointers, flags, masks */
337 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
338 struct hlist_node obj_list
;
339 /* Head of list of marks for an object [mark ref] */
340 struct fsnotify_mark_connector
*connector
;
341 /* Events types to ignore [mark->lock, group->mark_mutex] */
343 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01
344 #define FSNOTIFY_MARK_FLAG_ALIVE 0x02
345 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x04
346 unsigned int flags
; /* flags [mark->lock] */
349 #ifdef CONFIG_FSNOTIFY
351 /* called from the vfs helpers */
353 /* main fsnotify call to send events */
354 extern int fsnotify(struct inode
*to_tell
, __u32 mask
, const void *data
, int data_is
,
355 const struct qstr
*name
, u32 cookie
);
356 extern int __fsnotify_parent(const struct path
*path
, struct dentry
*dentry
, __u32 mask
);
357 extern void __fsnotify_inode_delete(struct inode
*inode
);
358 extern void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
);
359 extern void fsnotify_sb_delete(struct super_block
*sb
);
360 extern void fsnotify_nameremove(struct dentry
*dentry
, int isdir
);
361 extern u32
fsnotify_get_cookie(void);
363 static inline int fsnotify_inode_watches_children(struct inode
*inode
)
365 /* FS_EVENT_ON_CHILD is set if the inode may care */
366 if (!(inode
->i_fsnotify_mask
& FS_EVENT_ON_CHILD
))
368 /* this inode might care about child events, does it care about the
369 * specific set of events that can happen on a child? */
370 return inode
->i_fsnotify_mask
& FS_EVENTS_POSS_ON_CHILD
;
374 * Update the dentry with a flag indicating the interest of its parent to receive
375 * filesystem events when those events happens to this dentry->d_inode.
377 static inline void fsnotify_update_flags(struct dentry
*dentry
)
379 assert_spin_locked(&dentry
->d_lock
);
382 * Serialisation of setting PARENT_WATCHED on the dentries is provided
383 * by d_lock. If inotify_inode_watched changes after we have taken
384 * d_lock, the following __fsnotify_update_child_dentry_flags call will
385 * find our entry, so it will spin until we complete here, and update
386 * us with the new state.
388 if (fsnotify_inode_watches_children(dentry
->d_parent
->d_inode
))
389 dentry
->d_flags
|= DCACHE_FSNOTIFY_PARENT_WATCHED
;
391 dentry
->d_flags
&= ~DCACHE_FSNOTIFY_PARENT_WATCHED
;
394 /* called from fsnotify listeners, such as fanotify or dnotify */
396 /* create a new group */
397 extern struct fsnotify_group
*fsnotify_alloc_group(const struct fsnotify_ops
*ops
);
398 /* get reference to a group */
399 extern void fsnotify_get_group(struct fsnotify_group
*group
);
400 /* drop reference on a group from fsnotify_alloc_group */
401 extern void fsnotify_put_group(struct fsnotify_group
*group
);
402 /* group destruction begins, stop queuing new events */
403 extern void fsnotify_group_stop_queueing(struct fsnotify_group
*group
);
405 extern void fsnotify_destroy_group(struct fsnotify_group
*group
);
406 /* fasync handler function */
407 extern int fsnotify_fasync(int fd
, struct file
*file
, int on
);
408 /* Free event from memory */
409 extern void fsnotify_destroy_event(struct fsnotify_group
*group
,
410 struct fsnotify_event
*event
);
411 /* attach the event to the group notification queue */
412 extern int fsnotify_add_event(struct fsnotify_group
*group
,
413 struct fsnotify_event
*event
,
414 int (*merge
)(struct list_head
*,
415 struct fsnotify_event
*));
416 /* Queue overflow event to a notification group */
417 static inline void fsnotify_queue_overflow(struct fsnotify_group
*group
)
419 fsnotify_add_event(group
, group
->overflow_event
, NULL
);
422 /* true if the group notification queue is empty */
423 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group
*group
);
424 /* return, but do not dequeue the first event on the notification queue */
425 extern struct fsnotify_event
*fsnotify_peek_first_event(struct fsnotify_group
*group
);
426 /* return AND dequeue the first event on the notification queue */
427 extern struct fsnotify_event
*fsnotify_remove_first_event(struct fsnotify_group
*group
);
428 /* Remove event queued in the notification list */
429 extern void fsnotify_remove_queued_event(struct fsnotify_group
*group
,
430 struct fsnotify_event
*event
);
432 /* functions used to manipulate the marks attached to inodes */
434 /* Get mask of events for a list of marks */
435 extern __u32
fsnotify_conn_mask(struct fsnotify_mark_connector
*conn
);
436 /* Calculate mask of events for a list of marks */
437 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector
*conn
);
438 extern void fsnotify_init_mark(struct fsnotify_mark
*mark
,
439 struct fsnotify_group
*group
);
440 /* Find mark belonging to given group in the list of marks */
441 extern struct fsnotify_mark
*fsnotify_find_mark(fsnotify_connp_t
*connp
,
442 struct fsnotify_group
*group
);
443 /* Get cached fsid of filesystem containing object */
444 extern int fsnotify_get_conn_fsid(const struct fsnotify_mark_connector
*conn
,
445 __kernel_fsid_t
*fsid
);
446 /* attach the mark to the object */
447 extern int fsnotify_add_mark(struct fsnotify_mark
*mark
,
448 fsnotify_connp_t
*connp
, unsigned int type
,
449 int allow_dups
, __kernel_fsid_t
*fsid
);
450 extern int fsnotify_add_mark_locked(struct fsnotify_mark
*mark
,
451 fsnotify_connp_t
*connp
,
452 unsigned int type
, int allow_dups
,
453 __kernel_fsid_t
*fsid
);
455 /* attach the mark to the inode */
456 static inline int fsnotify_add_inode_mark(struct fsnotify_mark
*mark
,
460 return fsnotify_add_mark(mark
, &inode
->i_fsnotify_marks
,
461 FSNOTIFY_OBJ_TYPE_INODE
, allow_dups
, NULL
);
463 static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark
*mark
,
467 return fsnotify_add_mark_locked(mark
, &inode
->i_fsnotify_marks
,
468 FSNOTIFY_OBJ_TYPE_INODE
, allow_dups
,
472 /* given a group and a mark, flag mark to be freed when all references are dropped */
473 extern void fsnotify_destroy_mark(struct fsnotify_mark
*mark
,
474 struct fsnotify_group
*group
);
475 /* detach mark from inode / mount list, group list, drop inode reference */
476 extern void fsnotify_detach_mark(struct fsnotify_mark
*mark
);
478 extern void fsnotify_free_mark(struct fsnotify_mark
*mark
);
479 /* run all the marks in a group, and clear all of the marks attached to given object type */
480 extern void fsnotify_clear_marks_by_group(struct fsnotify_group
*group
, unsigned int type
);
481 /* run all the marks in a group, and clear all of the vfsmount marks */
482 static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group
*group
)
484 fsnotify_clear_marks_by_group(group
, FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL
);
486 /* run all the marks in a group, and clear all of the inode marks */
487 static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group
*group
)
489 fsnotify_clear_marks_by_group(group
, FSNOTIFY_OBJ_TYPE_INODE_FL
);
491 /* run all the marks in a group, and clear all of the sn marks */
492 static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group
*group
)
494 fsnotify_clear_marks_by_group(group
, FSNOTIFY_OBJ_TYPE_SB_FL
);
496 extern void fsnotify_get_mark(struct fsnotify_mark
*mark
);
497 extern void fsnotify_put_mark(struct fsnotify_mark
*mark
);
498 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info
*iter_info
);
499 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info
*iter_info
);
501 static inline void fsnotify_init_event(struct fsnotify_event
*event
,
504 INIT_LIST_HEAD(&event
->list
);
505 event
->inode
= inode
;
510 static inline int fsnotify(struct inode
*to_tell
, __u32 mask
, const void *data
, int data_is
,
511 const struct qstr
*name
, u32 cookie
)
516 static inline int __fsnotify_parent(const struct path
*path
, struct dentry
*dentry
, __u32 mask
)
521 static inline void __fsnotify_inode_delete(struct inode
*inode
)
524 static inline void __fsnotify_vfsmount_delete(struct vfsmount
*mnt
)
527 static inline void fsnotify_sb_delete(struct super_block
*sb
)
530 static inline void fsnotify_nameremove(struct dentry
*dentry
, int isdir
)
533 static inline void fsnotify_update_flags(struct dentry
*dentry
)
536 static inline u32
fsnotify_get_cookie(void)
541 static inline void fsnotify_unmount_inodes(struct super_block
*sb
)
544 #endif /* CONFIG_FSNOTIFY */
546 #endif /* __KERNEL __ */
548 #endif /* __LINUX_FSNOTIFY_BACKEND_H */