1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Filesystem access notification for Linux
4 *
5 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
6 */
7
8#ifndef __LINUX_FSNOTIFY_BACKEND_H
9#define __LINUX_FSNOTIFY_BACKEND_H
10
11#ifdef __KERNEL__
12
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>
22#include <linux/mempool.h>
23#include <linux/sched/mm.h>
24
25/*
26 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
27 * convert between them. dnotify only needs conversion at watch creation
28 * so no perf loss there. fanotify isn't defined yet, so it can use the
29 * wholes if it needs more events.
30 */
31#define FS_ACCESS 0x00000001 /* File was accessed */
32#define FS_MODIFY 0x00000002 /* File was modified */
33#define FS_ATTRIB 0x00000004 /* Metadata changed */
34#define FS_CLOSE_WRITE 0x00000008 /* Writable file was closed */
35#define FS_CLOSE_NOWRITE 0x00000010 /* Unwritable file closed */
36#define FS_OPEN 0x00000020 /* File was opened */
37#define FS_MOVED_FROM 0x00000040 /* File was moved from X */
38#define FS_MOVED_TO 0x00000080 /* File was moved to Y */
39#define FS_CREATE 0x00000100 /* Subfile was created */
40#define FS_DELETE 0x00000200 /* Subfile was deleted */
41#define FS_DELETE_SELF 0x00000400 /* Self was deleted */
42#define FS_MOVE_SELF 0x00000800 /* Self was moved */
43#define FS_OPEN_EXEC 0x00001000 /* File was opened for exec */
44
45#define FS_UNMOUNT 0x00002000 /* inode on umount fs */
46#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
47#define FS_ERROR 0x00008000 /* Filesystem Error (fanotify) */
48
49/*
50 * FS_IN_IGNORED overloads FS_ERROR. It is only used internally by inotify
51 * which does not support FS_ERROR.
52 */
53#define FS_IN_IGNORED 0x00008000 /* last inotify event here */
54
55#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
56#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
57#define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */
58/* #define FS_DIR_MODIFY 0x00080000 */ /* Deprecated (reserved) */
59
60#define FS_PRE_ACCESS 0x00100000 /* Pre-content access hook */
61
62#define FS_MNT_ATTACH 0x01000000 /* Mount was attached */
63#define FS_MNT_DETACH 0x02000000 /* Mount was detached */
64#define FS_MNT_MOVE (FS_MNT_ATTACH | FS_MNT_DETACH)
65
66/*
67 * Set on inode mark that cares about things that happen to its children.
68 * Always set for dnotify and inotify.
69 * Set on inode/sb/mount marks that care about parent/name info.
70 */
71#define FS_EVENT_ON_CHILD 0x08000000
72
73#define FS_RENAME 0x10000000 /* File was renamed */
74#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
75#define FS_ISDIR 0x40000000 /* event occurred against dir */
76
77#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
78
79/*
80 * Directory entry modification events - reported only to directory
81 * where entry is modified and not to a watching parent.
82 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event
83 * when a directory entry inside a child subdir changes.
84 */
85#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME)
86
87/* Mount namespace events */
88#define FSNOTIFY_MNT_EVENTS (FS_MNT_ATTACH | FS_MNT_DETACH)
89
90/* Content events can be used to inspect file content */
91#define FSNOTIFY_CONTENT_PERM_EVENTS (FS_OPEN_PERM | FS_OPEN_EXEC_PERM | \
92 FS_ACCESS_PERM)
93/* Pre-content events can be used to fill file content */
94#define FSNOTIFY_PRE_CONTENT_EVENTS (FS_PRE_ACCESS)
95
96#define ALL_FSNOTIFY_PERM_EVENTS (FSNOTIFY_CONTENT_PERM_EVENTS | \
97 FSNOTIFY_PRE_CONTENT_EVENTS)
98
99/*
100 * This is a list of all events that may get sent to a parent that is watching
101 * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory.
102 */
103#define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \
104 FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
105 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \
106 FS_OPEN | FS_OPEN_EXEC)
107
108/*
109 * This is a list of all events that may get sent with the parent inode as the
110 * @to_tell argument of fsnotify().
111 * It may include events that can be sent to an inode/sb/mount mark, but cannot
112 * be sent to a parent watching children.
113 */
114#define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD)
115
116/* Events that can be reported to backends */
117#define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \
118 FSNOTIFY_MNT_EVENTS | \
119 FS_EVENTS_POSS_ON_CHILD | \
120 FS_DELETE_SELF | FS_MOVE_SELF | \
121 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
122 FS_ERROR)
123
124/* Extra flags that may be reported with event or control handling of events */
125#define ALL_FSNOTIFY_FLAGS (FS_ISDIR | FS_EVENT_ON_CHILD | FS_DN_MULTISHOT)
126
127#define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
128
129struct fsnotify_group;
130struct fsnotify_event;
131struct fsnotify_mark;
132struct fsnotify_event_private_data;
133struct fsnotify_fname;
134struct fsnotify_iter_info;
135
136struct mem_cgroup;
137
138/*
139 * Each group much define these ops. The fsnotify infrastructure will call
140 * these operations for each relevant group.
141 *
142 * handle_event - main call for a group to handle an fs event
143 * @group: group to notify
144 * @mask: event type and flags
145 * @data: object that event happened on
146 * @data_type: type of object for fanotify_data_XXX() accessors
147 * @dir: optional directory associated with event -
148 * if @file_name is not NULL, this is the directory that
149 * @file_name is relative to
150 * @file_name: optional file name associated with event
151 * @cookie: inotify rename cookie
152 * @iter_info: array of marks from this group that are interested in the event
153 *
154 * handle_inode_event - simple variant of handle_event() for groups that only
155 * have inode marks and don't have ignore mask
156 * @mark: mark to notify
157 * @mask: event type and flags
158 * @inode: inode that event happened on
159 * @dir: optional directory associated with event -
160 * if @file_name is not NULL, this is the directory that
161 * @file_name is relative to.
162 * Either @inode or @dir must be non-NULL.
163 * @file_name: optional file name associated with event
164 * @cookie: inotify rename cookie
165 *
166 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
167 * freeing_mark - called when a mark is being destroyed for some reason. The group
168 * MUST be holding a reference on each mark and that reference must be
169 * dropped in this function. inotify uses this function to send
170 * userspace messages that marks have been removed.
171 */
172struct fsnotify_ops {
173 int (*handle_event)(struct fsnotify_group *group, u32 mask,
174 const void *data, int data_type, struct inode *dir,
175 const struct qstr *file_name, u32 cookie,
176 struct fsnotify_iter_info *iter_info);
177 int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask,
178 struct inode *inode, struct inode *dir,
179 const struct qstr *file_name, u32 cookie);
180 void (*free_group_priv)(struct fsnotify_group *group);
181 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
182 void (*free_event)(struct fsnotify_group *group, struct fsnotify_event *event);
183 /* called on final put+free to free memory */
184 void (*free_mark)(struct fsnotify_mark *mark);
185};
186
187/*
188 * all of the information about the original object we want to now send to
189 * a group. If you want to carry more info from the accessing task to the
190 * listener this structure is where you need to be adding fields.
191 */
192struct fsnotify_event {
193 struct list_head list;
194};
195
196/*
197 * fsnotify group priorities.
198 * Events are sent in order from highest priority to lowest priority.
199 */
200enum fsnotify_group_prio {
201 FSNOTIFY_PRIO_NORMAL = 0, /* normal notifiers, no permissions */
202 FSNOTIFY_PRIO_CONTENT, /* fanotify permission events */
203 FSNOTIFY_PRIO_PRE_CONTENT, /* fanotify pre-content events */
204 __FSNOTIFY_PRIO_NUM
205};
206
207/*
208 * A group is a "thing" that wants to receive notification about filesystem
209 * events. The mask holds the subset of event types this group cares about.
210 * refcnt on a group is up to the implementor and at any moment if it goes 0
211 * everything will be cleaned up.
212 */
213struct fsnotify_group {
214 const struct fsnotify_ops *ops; /* how this group handles things */
215
216 /*
217 * How the refcnt is used is up to each group. When the refcnt hits 0
218 * fsnotify will clean up all of the resources associated with this group.
219 * As an example, the dnotify group will always have a refcnt=1 and that
220 * will never change. Inotify, on the other hand, has a group per
221 * inotify_init() and the refcnt will hit 0 only when that fd has been
222 * closed.
223 */
224 refcount_t refcnt; /* things with interest in this group */
225
226 /* needed to send notification to userspace */
227 spinlock_t notification_lock; /* protect the notification_list */
228 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
229 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
230 unsigned int q_len; /* events on the queue */
231 unsigned int max_events; /* maximum events allowed on the list */
232 enum fsnotify_group_prio priority; /* priority for sending events */
233 bool shutdown; /* group is being shut down, don't queue more events */
234
235#define FSNOTIFY_GROUP_USER 0x01 /* user allocated group */
236#define FSNOTIFY_GROUP_DUPS 0x02 /* allow multiple marks per object */
237 int flags;
238 unsigned int owner_flags; /* stored flags of mark_mutex owner */
239
240 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
241 struct mutex mark_mutex; /* protect marks_list */
242 atomic_t user_waits; /* Number of tasks waiting for user
243 * response */
244 struct list_head marks_list; /* all inode marks for this group */
245
246 struct fasync_struct *fsn_fa; /* async notification */
247
248 struct fsnotify_event *overflow_event; /* Event we queue when the
249 * notification list is too
250 * full */
251
252 struct mem_cgroup *memcg; /* memcg to charge allocations */
253 struct user_namespace *user_ns; /* user ns where group was created */
254
255 /* groups can define private fields here or use the void *private */
256 union {
257 void *private;
258#ifdef CONFIG_INOTIFY_USER
259 struct inotify_group_private_data {
260 spinlock_t idr_lock;
261 struct idr idr;
262 struct ucounts *ucounts;
263 } inotify_data;
264#endif
265#ifdef CONFIG_FANOTIFY
266 struct fanotify_group_private_data {
267 /* Hash table of events for merge */
268 struct hlist_head *merge_hash;
269 /* allows a group to block waiting for a userspace response */
270 struct list_head access_list;
271 wait_queue_head_t access_waitq;
272 int flags; /* flags from fanotify_init() */
273 int f_flags; /* event_f_flags from fanotify_init() */
274 struct ucounts *ucounts;
275 mempool_t error_events_pool;
276 } fanotify_data;
277#endif /* CONFIG_FANOTIFY */
278 };
279};
280
281/*
282 * These helpers are used to prevent deadlock when reclaiming inodes with
283 * evictable marks of the same group that is allocating a new mark.
284 */
285static inline void fsnotify_group_lock(struct fsnotify_group *group)
286{
287 mutex_lock(&group->mark_mutex);
288 group->owner_flags = memalloc_nofs_save();
289}
290
291static inline void fsnotify_group_unlock(struct fsnotify_group *group)
292{
293 memalloc_nofs_restore(flags: group->owner_flags);
294 mutex_unlock(lock: &group->mark_mutex);
295}
296
297static inline void fsnotify_group_assert_locked(struct fsnotify_group *group)
298{
299 WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex));
300 WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS));
301}
302
303/* When calling fsnotify tell it if the data is a path or inode */
304enum fsnotify_data_type {
305 FSNOTIFY_EVENT_NONE,
306 FSNOTIFY_EVENT_FILE_RANGE,
307 FSNOTIFY_EVENT_PATH,
308 FSNOTIFY_EVENT_INODE,
309 FSNOTIFY_EVENT_DENTRY,
310 FSNOTIFY_EVENT_MNT,
311 FSNOTIFY_EVENT_ERROR,
312};
313
314struct fs_error_report {
315 int error;
316 struct inode *inode;
317 struct super_block *sb;
318};
319
320struct file_range {
321 const struct path *path;
322 loff_t pos;
323 size_t count;
324};
325
326static inline const struct path *file_range_path(const struct file_range *range)
327{
328 return range->path;
329}
330
331struct fsnotify_mnt {
332 const struct mnt_namespace *ns;
333 u64 mnt_id;
334};
335
336static inline struct inode *fsnotify_data_inode(const void *data, int data_type)
337{
338 switch (data_type) {
339 case FSNOTIFY_EVENT_INODE:
340 return (struct inode *)data;
341 case FSNOTIFY_EVENT_DENTRY:
342 return d_inode(dentry: data);
343 case FSNOTIFY_EVENT_PATH:
344 return d_inode(dentry: ((const struct path *)data)->dentry);
345 case FSNOTIFY_EVENT_FILE_RANGE:
346 return d_inode(dentry: file_range_path(range: data)->dentry);
347 case FSNOTIFY_EVENT_ERROR:
348 return ((struct fs_error_report *)data)->inode;
349 default:
350 return NULL;
351 }
352}
353
354static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type)
355{
356 switch (data_type) {
357 case FSNOTIFY_EVENT_DENTRY:
358 /* Non const is needed for dget() */
359 return (struct dentry *)data;
360 case FSNOTIFY_EVENT_PATH:
361 return ((const struct path *)data)->dentry;
362 case FSNOTIFY_EVENT_FILE_RANGE:
363 return file_range_path(range: data)->dentry;
364 default:
365 return NULL;
366 }
367}
368
369static inline const struct path *fsnotify_data_path(const void *data,
370 int data_type)
371{
372 switch (data_type) {
373 case FSNOTIFY_EVENT_PATH:
374 return data;
375 case FSNOTIFY_EVENT_FILE_RANGE:
376 return file_range_path(range: data);
377 default:
378 return NULL;
379 }
380}
381
382static inline struct super_block *fsnotify_data_sb(const void *data,
383 int data_type)
384{
385 switch (data_type) {
386 case FSNOTIFY_EVENT_INODE:
387 return ((struct inode *)data)->i_sb;
388 case FSNOTIFY_EVENT_DENTRY:
389 return ((struct dentry *)data)->d_sb;
390 case FSNOTIFY_EVENT_PATH:
391 return ((const struct path *)data)->dentry->d_sb;
392 case FSNOTIFY_EVENT_FILE_RANGE:
393 return file_range_path(range: data)->dentry->d_sb;
394 case FSNOTIFY_EVENT_ERROR:
395 return ((struct fs_error_report *) data)->sb;
396 default:
397 return NULL;
398 }
399}
400
401static inline const struct fsnotify_mnt *fsnotify_data_mnt(const void *data,
402 int data_type)
403{
404 switch (data_type) {
405 case FSNOTIFY_EVENT_MNT:
406 return data;
407 default:
408 return NULL;
409 }
410}
411
412static inline u64 fsnotify_data_mnt_id(const void *data, int data_type)
413{
414 const struct fsnotify_mnt *mnt_data = fsnotify_data_mnt(data, data_type);
415
416 return mnt_data ? mnt_data->mnt_id : 0;
417}
418
419static inline struct fs_error_report *fsnotify_data_error_report(
420 const void *data,
421 int data_type)
422{
423 switch (data_type) {
424 case FSNOTIFY_EVENT_ERROR:
425 return (struct fs_error_report *) data;
426 default:
427 return NULL;
428 }
429}
430
431static inline const struct file_range *fsnotify_data_file_range(
432 const void *data,
433 int data_type)
434{
435 switch (data_type) {
436 case FSNOTIFY_EVENT_FILE_RANGE:
437 return (struct file_range *)data;
438 default:
439 return NULL;
440 }
441}
442
443/*
444 * Index to merged marks iterator array that correlates to a type of watch.
445 * The type of watched object can be deduced from the iterator type, but not
446 * the other way around, because an event can match different watched objects
447 * of the same object type.
448 * For example, both parent and child are watching an object of type inode.
449 */
450enum fsnotify_iter_type {
451 FSNOTIFY_ITER_TYPE_INODE,
452 FSNOTIFY_ITER_TYPE_VFSMOUNT,
453 FSNOTIFY_ITER_TYPE_SB,
454 FSNOTIFY_ITER_TYPE_PARENT,
455 FSNOTIFY_ITER_TYPE_INODE2,
456 FSNOTIFY_ITER_TYPE_MNTNS,
457 FSNOTIFY_ITER_TYPE_COUNT
458};
459
460/* The type of object that a mark is attached to */
461enum fsnotify_obj_type {
462 FSNOTIFY_OBJ_TYPE_ANY = -1,
463 FSNOTIFY_OBJ_TYPE_INODE,
464 FSNOTIFY_OBJ_TYPE_VFSMOUNT,
465 FSNOTIFY_OBJ_TYPE_SB,
466 FSNOTIFY_OBJ_TYPE_MNTNS,
467 FSNOTIFY_OBJ_TYPE_COUNT,
468 FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
469};
470
471static inline bool fsnotify_valid_obj_type(unsigned int obj_type)
472{
473 return (obj_type < FSNOTIFY_OBJ_TYPE_COUNT);
474}
475
476struct fsnotify_iter_info {
477 struct fsnotify_mark *marks[FSNOTIFY_ITER_TYPE_COUNT];
478 struct fsnotify_group *current_group;
479 unsigned int report_mask;
480 int srcu_idx;
481};
482
483static inline bool fsnotify_iter_should_report_type(
484 struct fsnotify_iter_info *iter_info, int iter_type)
485{
486 return (iter_info->report_mask & (1U << iter_type));
487}
488
489static inline void fsnotify_iter_set_report_type(
490 struct fsnotify_iter_info *iter_info, int iter_type)
491{
492 iter_info->report_mask |= (1U << iter_type);
493}
494
495static inline struct fsnotify_mark *fsnotify_iter_mark(
496 struct fsnotify_iter_info *iter_info, int iter_type)
497{
498 if (fsnotify_iter_should_report_type(iter_info, iter_type))
499 return iter_info->marks[iter_type];
500 return NULL;
501}
502
503static inline int fsnotify_iter_step(struct fsnotify_iter_info *iter, int type,
504 struct fsnotify_mark **markp)
505{
506 while (type < FSNOTIFY_ITER_TYPE_COUNT) {
507 *markp = fsnotify_iter_mark(iter_info: iter, iter_type: type);
508 if (*markp)
509 break;
510 type++;
511 }
512 return type;
513}
514
515#define FSNOTIFY_ITER_FUNCS(name, NAME) \
516static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
517 struct fsnotify_iter_info *iter_info) \
518{ \
519 return fsnotify_iter_mark(iter_info, FSNOTIFY_ITER_TYPE_##NAME); \
520}
521
522FSNOTIFY_ITER_FUNCS(inode, INODE)
523FSNOTIFY_ITER_FUNCS(parent, PARENT)
524FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
525FSNOTIFY_ITER_FUNCS(sb, SB)
526
527#define fsnotify_foreach_iter_type(type) \
528 for (type = 0; type < FSNOTIFY_ITER_TYPE_COUNT; type++)
529#define fsnotify_foreach_iter_mark_type(iter, mark, type) \
530 for (type = 0; \
531 type = fsnotify_iter_step(iter, type, &mark), \
532 type < FSNOTIFY_ITER_TYPE_COUNT; \
533 type++)
534
535/*
536 * Inode/vfsmount/sb point to this structure which tracks all marks attached to
537 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
538 * structure. We destroy this structure when there are no more marks attached
539 * to it. The structure is protected by fsnotify_mark_srcu.
540 */
541struct fsnotify_mark_connector {
542 spinlock_t lock;
543 unsigned char type; /* Type of object [lock] */
544 unsigned char prio; /* Highest priority group */
545#define FSNOTIFY_CONN_FLAG_IS_WATCHED 0x01
546#define FSNOTIFY_CONN_FLAG_HAS_IREF 0x02
547 unsigned short flags; /* flags [lock] */
548 union {
549 /* Object pointer [lock] */
550 void *obj;
551 /* Used listing heads to free after srcu period expires */
552 struct fsnotify_mark_connector *destroy_next;
553 };
554 struct hlist_head list;
555};
556
557/*
558 * Container for per-sb fsnotify state (sb marks and more).
559 * Attached lazily on first marked object on the sb and freed when killing sb.
560 */
561struct fsnotify_sb_info {
562 struct fsnotify_mark_connector __rcu *sb_marks;
563 /*
564 * Number of inode/mount/sb objects that are being watched in this sb.
565 * Note that inodes objects are currently double-accounted.
566 *
567 * The value in watched_objects[prio] is the number of objects that are
568 * watched by groups of priority >= prio, so watched_objects[0] is the
569 * total number of watched objects in this sb.
570 */
571 atomic_long_t watched_objects[__FSNOTIFY_PRIO_NUM];
572};
573
574static inline struct fsnotify_sb_info *fsnotify_sb_info(struct super_block *sb)
575{
576#ifdef CONFIG_FSNOTIFY
577 return READ_ONCE(sb->s_fsnotify_info);
578#else
579 return NULL;
580#endif
581}
582
583static inline atomic_long_t *fsnotify_sb_watched_objects(struct super_block *sb)
584{
585 return &fsnotify_sb_info(sb)->watched_objects[0];
586}
587
588/*
589 * A mark is simply an object attached to an in core inode which allows an
590 * fsnotify listener to indicate they are either no longer interested in events
591 * of a type matching mask or only interested in those events.
592 *
593 * These are flushed when an inode is evicted from core and may be flushed
594 * when the inode is modified (as seen by fsnotify_access). Some fsnotify
595 * users (such as dnotify) will flush these when the open fd is closed and not
596 * at inode eviction or modification.
597 *
598 * Text in brackets is showing the lock(s) protecting modifications of a
599 * particular entry. obj_lock means either inode->i_lock or
600 * mnt->mnt_root->d_lock depending on the mark type.
601 */
602struct fsnotify_mark {
603 /* Mask this mark is for [mark->lock, group->mark_mutex] */
604 __u32 mask;
605 /* We hold one for presence in g_list. Also one ref for each 'thing'
606 * in kernel that found and may be using this mark. */
607 refcount_t refcnt;
608 /* Group this mark is for. Set on mark creation, stable until last ref
609 * is dropped */
610 struct fsnotify_group *group;
611 /* List of marks by group->marks_list. Also reused for queueing
612 * mark into destroy_list when it's waiting for the end of SRCU period
613 * before it can be freed. [group->mark_mutex] */
614 struct list_head g_list;
615 /* Protects inode / mnt pointers, flags, masks */
616 spinlock_t lock;
617 /* List of marks for inode / vfsmount [connector->lock, mark ref] */
618 struct hlist_node obj_list;
619 /* Head of list of marks for an object [mark ref] */
620 struct fsnotify_mark_connector *connector;
621 /* Events types and flags to ignore [mark->lock, group->mark_mutex] */
622 __u32 ignore_mask;
623 /* General fsnotify mark flags */
624#define FSNOTIFY_MARK_FLAG_ALIVE 0x0001
625#define FSNOTIFY_MARK_FLAG_ATTACHED 0x0002
626 /* inotify mark flags */
627#define FSNOTIFY_MARK_FLAG_EXCL_UNLINK 0x0010
628#define FSNOTIFY_MARK_FLAG_IN_ONESHOT 0x0020
629 /* fanotify mark flags */
630#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x0100
631#define FSNOTIFY_MARK_FLAG_NO_IREF 0x0200
632#define FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS 0x0400
633#define FSNOTIFY_MARK_FLAG_HAS_FSID 0x0800
634#define FSNOTIFY_MARK_FLAG_WEAK_FSID 0x1000
635 unsigned int flags; /* flags [mark->lock] */
636};
637
638#ifdef CONFIG_FSNOTIFY
639
640/* called from the vfs helpers */
641
642/* main fsnotify call to send events */
643extern int fsnotify(__u32 mask, const void *data, int data_type,
644 struct inode *dir, const struct qstr *name,
645 struct inode *inode, u32 cookie);
646extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
647 int data_type);
648extern void __fsnotify_inode_delete(struct inode *inode);
649extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
650extern void fsnotify_sb_delete(struct super_block *sb);
651extern void __fsnotify_mntns_delete(struct mnt_namespace *mntns);
652extern void fsnotify_sb_free(struct super_block *sb);
653extern u32 fsnotify_get_cookie(void);
654extern void fsnotify_mnt(__u32 mask, struct mnt_namespace *ns, struct vfsmount *mnt);
655
656static inline __u32 fsnotify_parent_needed_mask(__u32 mask)
657{
658 /* FS_EVENT_ON_CHILD is set on marks that want parent/name info */
659 if (!(mask & FS_EVENT_ON_CHILD))
660 return 0;
661 /*
662 * This object might be watched by a mark that cares about parent/name
663 * info, does it care about the specific set of events that can be
664 * reported with parent/name info?
665 */
666 return mask & FS_EVENTS_POSS_TO_PARENT;
667}
668
669static inline int fsnotify_inode_watches_children(struct inode *inode)
670{
671 __u32 parent_mask = READ_ONCE(inode->i_fsnotify_mask);
672
673 /* FS_EVENT_ON_CHILD is set if the inode may care */
674 if (!(parent_mask & FS_EVENT_ON_CHILD))
675 return 0;
676 /* this inode might care about child events, does it care about the
677 * specific set of events that can happen on a child? */
678 return parent_mask & FS_EVENTS_POSS_ON_CHILD;
679}
680
681/*
682 * Update the dentry with a flag indicating the interest of its parent to receive
683 * filesystem events when those events happens to this dentry->d_inode.
684 */
685static inline void fsnotify_update_flags(struct dentry *dentry)
686{
687 assert_spin_locked(&dentry->d_lock);
688
689 /*
690 * Serialisation of setting PARENT_WATCHED on the dentries is provided
691 * by d_lock. If inotify_inode_watched changes after we have taken
692 * d_lock, the following fsnotify_set_children_dentry_flags call will
693 * find our entry, so it will spin until we complete here, and update
694 * us with the new state.
695 */
696 if (fsnotify_inode_watches_children(inode: dentry->d_parent->d_inode))
697 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
698 else
699 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
700}
701
702/* called from fsnotify listeners, such as fanotify or dnotify */
703
704/* create a new group */
705extern struct fsnotify_group *fsnotify_alloc_group(
706 const struct fsnotify_ops *ops,
707 int flags);
708/* get reference to a group */
709extern void fsnotify_get_group(struct fsnotify_group *group);
710/* drop reference on a group from fsnotify_alloc_group */
711extern void fsnotify_put_group(struct fsnotify_group *group);
712/* group destruction begins, stop queuing new events */
713extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
714/* destroy group */
715extern void fsnotify_destroy_group(struct fsnotify_group *group);
716/* fasync handler function */
717extern int fsnotify_fasync(int fd, struct file *file, int on);
718/* Free event from memory */
719extern void fsnotify_destroy_event(struct fsnotify_group *group,
720 struct fsnotify_event *event);
721/* attach the event to the group notification queue */
722extern int fsnotify_insert_event(struct fsnotify_group *group,
723 struct fsnotify_event *event,
724 int (*merge)(struct fsnotify_group *,
725 struct fsnotify_event *),
726 void (*insert)(struct fsnotify_group *,
727 struct fsnotify_event *));
728
729static inline int fsnotify_add_event(struct fsnotify_group *group,
730 struct fsnotify_event *event,
731 int (*merge)(struct fsnotify_group *,
732 struct fsnotify_event *))
733{
734 return fsnotify_insert_event(group, event, merge, NULL);
735}
736
737/* Queue overflow event to a notification group */
738static inline void fsnotify_queue_overflow(struct fsnotify_group *group)
739{
740 fsnotify_add_event(group, event: group->overflow_event, NULL);
741}
742
743static inline bool fsnotify_is_overflow_event(u32 mask)
744{
745 return mask & FS_Q_OVERFLOW;
746}
747
748static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
749{
750 assert_spin_locked(&group->notification_lock);
751
752 return list_empty(head: &group->notification_list);
753}
754
755extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
756/* return, but do not dequeue the first event on the notification queue */
757extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
758/* return AND dequeue the first event on the notification queue */
759extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
760/* Remove event queued in the notification list */
761extern void fsnotify_remove_queued_event(struct fsnotify_group *group,
762 struct fsnotify_event *event);
763
764/* functions used to manipulate the marks attached to inodes */
765
766/*
767 * Canonical "ignore mask" including event flags.
768 *
769 * Note the subtle semantic difference from the legacy ->ignored_mask.
770 * ->ignored_mask traditionally only meant which events should be ignored,
771 * while ->ignore_mask also includes flags regarding the type of objects on
772 * which events should be ignored.
773 */
774static inline __u32 fsnotify_ignore_mask(struct fsnotify_mark *mark)
775{
776 __u32 ignore_mask = mark->ignore_mask;
777
778 /* The event flags in ignore mask take effect */
779 if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
780 return ignore_mask;
781
782 /*
783 * Legacy behavior:
784 * - Always ignore events on dir
785 * - Ignore events on child if parent is watching children
786 */
787 ignore_mask |= FS_ISDIR;
788 ignore_mask &= ~FS_EVENT_ON_CHILD;
789 ignore_mask |= mark->mask & FS_EVENT_ON_CHILD;
790
791 return ignore_mask;
792}
793
794/* Legacy ignored_mask - only event types to ignore */
795static inline __u32 fsnotify_ignored_events(struct fsnotify_mark *mark)
796{
797 return mark->ignore_mask & ALL_FSNOTIFY_EVENTS;
798}
799
800/*
801 * Check if mask (or ignore mask) should be applied depending if victim is a
802 * directory and whether it is reported to a watching parent.
803 */
804static inline bool fsnotify_mask_applicable(__u32 mask, bool is_dir,
805 int iter_type)
806{
807 /* Should mask be applied to a directory? */
808 if (is_dir && !(mask & FS_ISDIR))
809 return false;
810
811 /* Should mask be applied to a child? */
812 if (iter_type == FSNOTIFY_ITER_TYPE_PARENT &&
813 !(mask & FS_EVENT_ON_CHILD))
814 return false;
815
816 return true;
817}
818
819/*
820 * Effective ignore mask taking into account if event victim is a
821 * directory and whether it is reported to a watching parent.
822 */
823static inline __u32 fsnotify_effective_ignore_mask(struct fsnotify_mark *mark,
824 bool is_dir, int iter_type)
825{
826 __u32 ignore_mask = fsnotify_ignored_events(mark);
827
828 if (!ignore_mask)
829 return 0;
830
831 /* For non-dir and non-child, no need to consult the event flags */
832 if (!is_dir && iter_type != FSNOTIFY_ITER_TYPE_PARENT)
833 return ignore_mask;
834
835 ignore_mask = fsnotify_ignore_mask(mark);
836 if (!fsnotify_mask_applicable(mask: ignore_mask, is_dir, iter_type))
837 return 0;
838
839 return ignore_mask & ALL_FSNOTIFY_EVENTS;
840}
841
842/* Get mask for calculating object interest taking ignore mask into account */
843static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark)
844{
845 __u32 mask = mark->mask;
846
847 if (!fsnotify_ignored_events(mark))
848 return mask;
849
850 /* Interest in FS_MODIFY may be needed for clearing ignore mask */
851 if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
852 mask |= FS_MODIFY;
853
854 /*
855 * If mark is interested in ignoring events on children, the object must
856 * show interest in those events for fsnotify_parent() to notice it.
857 */
858 return mask | mark->ignore_mask;
859}
860
861/* Get mask of events for a list of marks */
862extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn);
863/* Calculate mask of events for a list of marks */
864extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn);
865extern void fsnotify_init_mark(struct fsnotify_mark *mark,
866 struct fsnotify_group *group);
867/* Find mark belonging to given group in the list of marks */
868struct fsnotify_mark *fsnotify_find_mark(void *obj, unsigned int obj_type,
869 struct fsnotify_group *group);
870/* attach the mark to the object */
871int fsnotify_add_mark(struct fsnotify_mark *mark, void *obj,
872 unsigned int obj_type, int add_flags);
873int fsnotify_add_mark_locked(struct fsnotify_mark *mark, void *obj,
874 unsigned int obj_type, int add_flags);
875
876/* attach the mark to the inode */
877static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
878 struct inode *inode,
879 int add_flags)
880{
881 return fsnotify_add_mark(mark, obj: inode, obj_type: FSNOTIFY_OBJ_TYPE_INODE,
882 add_flags);
883}
884static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark,
885 struct inode *inode,
886 int add_flags)
887{
888 return fsnotify_add_mark_locked(mark, obj: inode, obj_type: FSNOTIFY_OBJ_TYPE_INODE,
889 add_flags);
890}
891
892static inline struct fsnotify_mark *fsnotify_find_inode_mark(
893 struct inode *inode,
894 struct fsnotify_group *group)
895{
896 return fsnotify_find_mark(obj: inode, obj_type: FSNOTIFY_OBJ_TYPE_INODE, group);
897}
898
899/* given a group and a mark, flag mark to be freed when all references are dropped */
900extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
901 struct fsnotify_group *group);
902/* detach mark from inode / mount list, group list, drop inode reference */
903extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
904/* free mark */
905extern void fsnotify_free_mark(struct fsnotify_mark *mark);
906/* Wait until all marks queued for destruction are destroyed */
907extern void fsnotify_wait_marks_destroyed(void);
908/* Clear all of the marks of a group attached to a given object type */
909extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group,
910 unsigned int obj_type);
911extern void fsnotify_get_mark(struct fsnotify_mark *mark);
912extern void fsnotify_put_mark(struct fsnotify_mark *mark);
913extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
914extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
915
916static inline void fsnotify_init_event(struct fsnotify_event *event)
917{
918 INIT_LIST_HEAD(list: &event->list);
919}
920int fsnotify_pre_content(const struct path *path, const loff_t *ppos,
921 size_t count);
922
923#else
924
925static inline int fsnotify_pre_content(const struct path *path,
926 const loff_t *ppos, size_t count)
927{
928 return 0;
929}
930
931static inline int fsnotify(__u32 mask, const void *data, int data_type,
932 struct inode *dir, const struct qstr *name,
933 struct inode *inode, u32 cookie)
934{
935 return 0;
936}
937
938static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask,
939 const void *data, int data_type)
940{
941 return 0;
942}
943
944static inline void __fsnotify_inode_delete(struct inode *inode)
945{}
946
947static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
948{}
949
950static inline void fsnotify_sb_delete(struct super_block *sb)
951{}
952
953static inline void __fsnotify_mntns_delete(struct mnt_namespace *mntns)
954{}
955
956static inline void fsnotify_sb_free(struct super_block *sb)
957{}
958
959static inline void fsnotify_update_flags(struct dentry *dentry)
960{}
961
962static inline u32 fsnotify_get_cookie(void)
963{
964 return 0;
965}
966
967static inline void fsnotify_unmount_inodes(struct super_block *sb)
968{}
969
970static inline void fsnotify_mnt(__u32 mask, struct mnt_namespace *ns, struct vfsmount *mnt)
971{}
972
973#endif /* CONFIG_FSNOTIFY */
974
975#endif /* __KERNEL __ */
976
977#endif /* __LINUX_FSNOTIFY_BACKEND_H */
978

source code of linux/include/linux/fsnotify_backend.h