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1 : : /*
2 : : * Filesystem access notification for Linux
3 : : *
4 : : * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
5 : : */
6 : :
7 : : #ifndef __LINUX_FSNOTIFY_BACKEND_H
8 : : #define __LINUX_FSNOTIFY_BACKEND_H
9 : :
10 : : #ifdef __KERNEL__
11 : :
12 : : #include <linux/idr.h> /* inotify uses this */
13 : : #include <linux/fs.h> /* struct inode */
14 : : #include <linux/list.h>
15 : : #include <linux/path.h> /* struct path */
16 : : #include <linux/spinlock.h>
17 : : #include <linux/types.h>
18 : : #include <linux/atomic.h>
19 : :
20 : : /*
21 : : * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
22 : : * convert between them. dnotify only needs conversion at watch creation
23 : : * so no perf loss there. fanotify isn't defined yet, so it can use the
24 : : * wholes if it needs more events.
25 : : */
26 : : #define FS_ACCESS 0x00000001 /* File was accessed */
27 : : #define FS_MODIFY 0x00000002 /* File was modified */
28 : : #define FS_ATTRIB 0x00000004 /* Metadata changed */
29 : : #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
30 : : #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
31 : : #define FS_OPEN 0x00000020 /* File was opened */
32 : : #define FS_MOVED_FROM 0x00000040 /* File was moved from X */
33 : : #define FS_MOVED_TO 0x00000080 /* File was moved to Y */
34 : : #define FS_CREATE 0x00000100 /* Subfile was created */
35 : : #define FS_DELETE 0x00000200 /* Subfile was deleted */
36 : : #define FS_DELETE_SELF 0x00000400 /* Self was deleted */
37 : : #define FS_MOVE_SELF 0x00000800 /* Self was moved */
38 : :
39 : : #define FS_UNMOUNT 0x00002000 /* inode on umount fs */
40 : : #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
41 : : #define FS_IN_IGNORED 0x00008000 /* last inotify event here */
42 : :
43 : : #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
44 : : #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
45 : :
46 : : #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
47 : : #define FS_ISDIR 0x40000000 /* event occurred against dir */
48 : : #define FS_IN_ONESHOT 0x80000000 /* only send event once */
49 : :
50 : : #define FS_DN_RENAME 0x10000000 /* file renamed */
51 : : #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
52 : :
53 : : /* This inode cares about things that happen to its children. Always set for
54 : : * dnotify and inotify. */
55 : : #define FS_EVENT_ON_CHILD 0x08000000
56 : :
57 : : /* This is a list of all events that may get sent to a parernt based on fs event
58 : : * happening to inodes inside that directory */
59 : : #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
60 : : FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
61 : : FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
62 : : FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
63 : :
64 : : #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
65 : :
66 : : #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
67 : :
68 : : #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
69 : : FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
70 : : FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
71 : : FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
72 : : FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
73 : : FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
74 : : FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
75 : : FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
76 : :
77 : : struct fsnotify_group;
78 : : struct fsnotify_event;
79 : : struct fsnotify_mark;
80 : : struct fsnotify_event_private_data;
81 : : struct fsnotify_fname;
82 : :
83 : : /*
84 : : * Each group much define these ops. The fsnotify infrastructure will call
85 : : * these operations for each relevant group.
86 : : *
87 : : * should_send_event - given a group, inode, and mask this function determines
88 : : * if the group is interested in this event.
89 : : * handle_event - main call for a group to handle an fs event
90 : : * free_group_priv - called when a group refcnt hits 0 to clean up the private union
91 : : * freeing_mark - called when a mark is being destroyed for some reason. The group
92 : : * MUST be holding a reference on each mark and that reference must be
93 : : * dropped in this function. inotify uses this function to send
94 : : * userspace messages that marks have been removed.
95 : : */
96 : : struct fsnotify_ops {
97 : : int (*handle_event)(struct fsnotify_group *group,
98 : : struct inode *inode,
99 : : struct fsnotify_mark *inode_mark,
100 : : struct fsnotify_mark *vfsmount_mark,
101 : : u32 mask, void *data, int data_type,
102 : : const unsigned char *file_name, u32 cookie);
103 : : void (*free_group_priv)(struct fsnotify_group *group);
104 : : void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
105 : : void (*free_event)(struct fsnotify_event *event);
106 : : };
107 : :
108 : : /*
109 : : * all of the information about the original object we want to now send to
110 : : * a group. If you want to carry more info from the accessing task to the
111 : : * listener this structure is where you need to be adding fields.
112 : : */
113 : : struct fsnotify_event {
114 : : struct list_head list;
115 : : /* inode may ONLY be dereferenced during handle_event(). */
116 : : struct inode *inode; /* either the inode the event happened to or its parent */
117 : : u32 mask; /* the type of access, bitwise OR for FS_* event types */
118 : : };
119 : :
120 : : /*
121 : : * A group is a "thing" that wants to receive notification about filesystem
122 : : * events. The mask holds the subset of event types this group cares about.
123 : : * refcnt on a group is up to the implementor and at any moment if it goes 0
124 : : * everything will be cleaned up.
125 : : */
126 : : struct fsnotify_group {
127 : : /*
128 : : * How the refcnt is used is up to each group. When the refcnt hits 0
129 : : * fsnotify will clean up all of the resources associated with this group.
130 : : * As an example, the dnotify group will always have a refcnt=1 and that
131 : : * will never change. Inotify, on the other hand, has a group per
132 : : * inotify_init() and the refcnt will hit 0 only when that fd has been
133 : : * closed.
134 : : */
135 : : atomic_t refcnt; /* things with interest in this group */
136 : :
137 : : const struct fsnotify_ops *ops; /* how this group handles things */
138 : :
139 : : /* needed to send notification to userspace */
140 : : struct mutex notification_mutex; /* protect the notification_list */
141 : : struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
142 : : wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
143 : : unsigned int q_len; /* events on the queue */
144 : : unsigned int max_events; /* maximum events allowed on the list */
145 : : /*
146 : : * Valid fsnotify group priorities. Events are send in order from highest
147 : : * priority to lowest priority. We default to the lowest priority.
148 : : */
149 : : #define FS_PRIO_0 0 /* normal notifiers, no permissions */
150 : : #define FS_PRIO_1 1 /* fanotify content based access control */
151 : : #define FS_PRIO_2 2 /* fanotify pre-content access */
152 : : unsigned int priority;
153 : :
154 : : /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
155 : : struct mutex mark_mutex; /* protect marks_list */
156 : : atomic_t num_marks; /* 1 for each mark and 1 for not being
157 : : * past the point of no return when freeing
158 : : * a group */
159 : : struct list_head marks_list; /* all inode marks for this group */
160 : :
161 : : struct fasync_struct *fsn_fa; /* async notification */
162 : :
163 : : struct fsnotify_event *overflow_event; /* Event we queue when the
164 : : * notification list is too
165 : : * full */
166 : :
167 : : /* groups can define private fields here or use the void *private */
168 : : union {
169 : : void *private;
170 : : #ifdef CONFIG_INOTIFY_USER
171 : : struct inotify_group_private_data {
172 : : spinlock_t idr_lock;
173 : : struct idr idr;
174 : : struct user_struct *user;
175 : : } inotify_data;
176 : : #endif
177 : : #ifdef CONFIG_FANOTIFY
178 : : struct fanotify_group_private_data {
179 : : #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
180 : : /* allows a group to block waiting for a userspace response */
181 : : struct mutex access_mutex;
182 : : struct list_head access_list;
183 : : wait_queue_head_t access_waitq;
184 : : atomic_t bypass_perm;
185 : : #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
186 : : int f_flags;
187 : : unsigned int max_marks;
188 : : struct user_struct *user;
189 : : } fanotify_data;
190 : : #endif /* CONFIG_FANOTIFY */
191 : : };
192 : : };
193 : :
194 : : /* when calling fsnotify tell it if the data is a path or inode */
195 : : #define FSNOTIFY_EVENT_NONE 0
196 : : #define FSNOTIFY_EVENT_PATH 1
197 : : #define FSNOTIFY_EVENT_INODE 2
198 : :
199 : : /*
200 : : * Inode specific fields in an fsnotify_mark
201 : : */
202 : : struct fsnotify_inode_mark {
203 : : struct inode *inode; /* inode this mark is associated with */
204 : : struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */
205 : : struct list_head free_i_list; /* tmp list used when freeing this mark */
206 : : };
207 : :
208 : : /*
209 : : * Mount point specific fields in an fsnotify_mark
210 : : */
211 : : struct fsnotify_vfsmount_mark {
212 : : struct vfsmount *mnt; /* vfsmount this mark is associated with */
213 : : struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */
214 : : struct list_head free_m_list; /* tmp list used when freeing this mark */
215 : : };
216 : :
217 : : /*
218 : : * a mark is simply an object attached to an in core inode which allows an
219 : : * fsnotify listener to indicate they are either no longer interested in events
220 : : * of a type matching mask or only interested in those events.
221 : : *
222 : : * these are flushed when an inode is evicted from core and may be flushed
223 : : * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
224 : : * (such as dnotify) will flush these when the open fd is closed and not at
225 : : * inode eviction or modification.
226 : : */
227 : : struct fsnotify_mark {
228 : : __u32 mask; /* mask this mark is for */
229 : : /* we hold ref for each i_list and g_list. also one ref for each 'thing'
230 : : * in kernel that found and may be using this mark. */
231 : : atomic_t refcnt; /* active things looking at this mark */
232 : : struct fsnotify_group *group; /* group this mark is for */
233 : : struct list_head g_list; /* list of marks by group->i_fsnotify_marks */
234 : : spinlock_t lock; /* protect group and inode */
235 : : union {
236 : : struct fsnotify_inode_mark i;
237 : : struct fsnotify_vfsmount_mark m;
238 : : };
239 : : __u32 ignored_mask; /* events types to ignore */
240 : : #define FSNOTIFY_MARK_FLAG_INODE 0x01
241 : : #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
242 : : #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
243 : : #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
244 : : #define FSNOTIFY_MARK_FLAG_ALIVE 0x10
245 : : unsigned int flags; /* vfsmount or inode mark? */
246 : : struct list_head destroy_list;
247 : : void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
248 : : };
249 : :
250 : : #ifdef CONFIG_FSNOTIFY
251 : :
252 : : /* called from the vfs helpers */
253 : :
254 : : /* main fsnotify call to send events */
255 : : extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
256 : : const unsigned char *name, u32 cookie);
257 : : extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
258 : : extern void __fsnotify_inode_delete(struct inode *inode);
259 : : extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
260 : : extern u32 fsnotify_get_cookie(void);
261 : :
262 : : static inline int fsnotify_inode_watches_children(struct inode *inode)
263 : : {
264 : : /* FS_EVENT_ON_CHILD is set if the inode may care */
265 [ + + ][ + + ]: 2224003 : if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
[ + + ][ + + ]
266 : : return 0;
267 : : /* this inode might care about child events, does it care about the
268 : : * specific set of events that can happen on a child? */
269 : 368704 : return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
270 : : }
271 : :
272 : : /*
273 : : * Update the dentry with a flag indicating the interest of its parent to receive
274 : : * filesystem events when those events happens to this dentry->d_inode.
275 : : */
276 : : static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
277 : : {
278 : : struct dentry *parent;
279 : :
280 [ - + ][ - + ]: 4401284 : assert_spin_locked(&dentry->d_lock);
281 : :
282 : : /*
283 : : * Serialisation of setting PARENT_WATCHED on the dentries is provided
284 : : * by d_lock. If inotify_inode_watched changes after we have taken
285 : : * d_lock, the following __fsnotify_update_child_dentry_flags call will
286 : : * find our entry, so it will spin until we complete here, and update
287 : : * us with the new state.
288 : : */
289 : 1836750 : parent = dentry->d_parent;
290 [ + - ][ + + ]: 3698834 : if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
[ + ][ + + ]
291 : 6787 : dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
292 : : else
293 : 1829963 : dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
294 : : }
295 : :
296 : : /*
297 : : * fsnotify_d_instantiate - instantiate a dentry for inode
298 : : */
299 : : static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
300 : : {
301 [ + + ]: 2470549 : if (!inode)
302 : : return;
303 : :
304 : : spin_lock(&dentry->d_lock);
305 : : __fsnotify_update_dcache_flags(dentry);
306 : : spin_unlock(&dentry->d_lock);
307 : : }
308 : :
309 : : /* called from fsnotify listeners, such as fanotify or dnotify */
310 : :
311 : : /* create a new group */
312 : : extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
313 : : /* get reference to a group */
314 : : extern void fsnotify_get_group(struct fsnotify_group *group);
315 : : /* drop reference on a group from fsnotify_alloc_group */
316 : : extern void fsnotify_put_group(struct fsnotify_group *group);
317 : : /* destroy group */
318 : : extern void fsnotify_destroy_group(struct fsnotify_group *group);
319 : : /* fasync handler function */
320 : : extern int fsnotify_fasync(int fd, struct file *file, int on);
321 : : /* Free event from memory */
322 : : extern void fsnotify_destroy_event(struct fsnotify_group *group,
323 : : struct fsnotify_event *event);
324 : : /* attach the event to the group notification queue */
325 : : extern int fsnotify_add_notify_event(struct fsnotify_group *group,
326 : : struct fsnotify_event *event,
327 : : int (*merge)(struct list_head *,
328 : : struct fsnotify_event *));
329 : : /* true if the group notification queue is empty */
330 : : extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
331 : : /* return, but do not dequeue the first event on the notification queue */
332 : : extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
333 : : /* return AND dequeue the first event on the notification queue */
334 : : extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
335 : :
336 : : /* functions used to manipulate the marks attached to inodes */
337 : :
338 : : /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
339 : : extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
340 : : /* run all marks associated with an inode and update inode->i_fsnotify_mask */
341 : : extern void fsnotify_recalc_inode_mask(struct inode *inode);
342 : : extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
343 : : /* find (and take a reference) to a mark associated with group and inode */
344 : : extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
345 : : /* find (and take a reference) to a mark associated with group and vfsmount */
346 : : extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
347 : : /* copy the values from old into new */
348 : : extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
349 : : /* set the ignored_mask of a mark */
350 : : extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
351 : : /* set the mask of a mark (might pin the object into memory */
352 : : extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
353 : : /* attach the mark to both the group and the inode */
354 : : extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
355 : : struct inode *inode, struct vfsmount *mnt, int allow_dups);
356 : : extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
357 : : struct inode *inode, struct vfsmount *mnt, int allow_dups);
358 : : /* given a group and a mark, flag mark to be freed when all references are dropped */
359 : : extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
360 : : struct fsnotify_group *group);
361 : : extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark,
362 : : struct fsnotify_group *group);
363 : : /* run all the marks in a group, and clear all of the vfsmount marks */
364 : : extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
365 : : /* run all the marks in a group, and clear all of the inode marks */
366 : : extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
367 : : /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
368 : : extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
369 : : /* run all the marks in a group, and flag them to be freed */
370 : : extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
371 : : extern void fsnotify_get_mark(struct fsnotify_mark *mark);
372 : : extern void fsnotify_put_mark(struct fsnotify_mark *mark);
373 : : extern void fsnotify_unmount_inodes(struct list_head *list);
374 : :
375 : : /* put here because inotify does some weird stuff when destroying watches */
376 : : extern void fsnotify_init_event(struct fsnotify_event *event,
377 : : struct inode *to_tell, u32 mask);
378 : :
379 : : #else
380 : :
381 : : static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
382 : : const unsigned char *name, u32 cookie)
383 : : {
384 : : return 0;
385 : : }
386 : :
387 : : static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
388 : : {
389 : : return 0;
390 : : }
391 : :
392 : : static inline void __fsnotify_inode_delete(struct inode *inode)
393 : : {}
394 : :
395 : : static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
396 : : {}
397 : :
398 : : static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
399 : : {}
400 : :
401 : : static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
402 : : {}
403 : :
404 : : static inline u32 fsnotify_get_cookie(void)
405 : : {
406 : : return 0;
407 : : }
408 : :
409 : : static inline void fsnotify_unmount_inodes(struct list_head *list)
410 : : {}
411 : :
412 : : #endif /* CONFIG_FSNOTIFY */
413 : :
414 : : #endif /* __KERNEL __ */
415 : :
416 : : #endif /* __LINUX_FSNOTIFY_BACKEND_H */
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