1 /* 2 * Filesystem access notification for Linux 3 * 4 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <[email protected]> 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 19 #include <linux/atomic.h> 20 21 /* 22 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily 23 * convert between them. dnotify only needs conversion at watch creation 24 * so no perf loss there. fanotify isn't defined yet, so it can use the 25 * wholes if it needs more events. 26 */ 27 #define FS_ACCESS 0x00000001 /* File was accessed */ 28 #define FS_MODIFY 0x00000002 /* File was modified */ 29 #define FS_ATTRIB 0x00000004 /* Metadata changed */ 30 #define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */ 31 #define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */ 32 #define FS_OPEN 0x00000020 /* File was opened */ 33 #define FS_MOVED_FROM 0x00000040 /* File was moved from X */ 34 #define FS_MOVED_TO 0x00000080 /* File was moved to Y */ 35 #define FS_CREATE 0x00000100 /* Subfile was created */ 36 #define FS_DELETE 0x00000200 /* Subfile was deleted */ 37 #define FS_DELETE_SELF 0x00000400 /* Self was deleted */ 38 #define FS_MOVE_SELF 0x00000800 /* Self was moved */ 39 40 #define FS_UNMOUNT 0x00002000 /* inode on umount fs */ 41 #define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ 42 #define FS_IN_IGNORED 0x00008000 /* last inotify event here */ 43 44 #define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ 45 #define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ 46 47 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ 48 #define FS_ISDIR 0x40000000 /* event occurred against dir */ 49 #define FS_IN_ONESHOT 0x80000000 /* only send event once */ 50 51 #define FS_DN_RENAME 0x10000000 /* file renamed */ 52 #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ 53 54 /* This inode cares about things that happen to its children. Always set for 55 * dnotify and inotify. */ 56 #define FS_EVENT_ON_CHILD 0x08000000 57 58 /* This is a list of all events that may get sent to a parernt based on fs event 59 * happening to inodes inside that directory */ 60 #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ 61 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ 62 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ 63 FS_DELETE) 64 65 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 66 67 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM) 68 69 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \ 70 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \ 71 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \ 72 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \ 73 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \ 74 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \ 75 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \ 76 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD) 77 78 struct fsnotify_group; 79 struct fsnotify_event; 80 struct fsnotify_mark; 81 struct fsnotify_event_private_data; 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 - this means that a mark has been flagged to die when everything 92 * finishes using it. The function is supplied with what must be a 93 * valid group and inode to use to clean up. 94 */ 95 struct fsnotify_ops { 96 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, 97 struct fsnotify_mark *inode_mark, 98 struct fsnotify_mark *vfsmount_mark, 99 __u32 mask, void *data, int data_type); 100 int (*handle_event)(struct fsnotify_group *group, 101 struct fsnotify_mark *inode_mark, 102 struct fsnotify_mark *vfsmount_mark, 103 struct fsnotify_event *event); 104 void (*free_group_priv)(struct fsnotify_group *group); 105 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 106 void (*free_event_priv)(struct fsnotify_event_private_data *priv); 107 }; 108 109 /* 110 * A group is a "thing" that wants to receive notification about filesystem 111 * events. The mask holds the subset of event types this group cares about. 112 * refcnt on a group is up to the implementor and at any moment if it goes 0 113 * everything will be cleaned up. 114 */ 115 struct fsnotify_group { 116 /* 117 * How the refcnt is used is up to each group. When the refcnt hits 0 118 * fsnotify will clean up all of the resources associated with this group. 119 * As an example, the dnotify group will always have a refcnt=1 and that 120 * will never change. Inotify, on the other hand, has a group per 121 * inotify_init() and the refcnt will hit 0 only when that fd has been 122 * closed. 123 */ 124 atomic_t refcnt; /* things with interest in this group */ 125 126 const struct fsnotify_ops *ops; /* how this group handles things */ 127 128 /* needed to send notification to userspace */ 129 struct mutex notification_mutex; /* protect the notification_list */ 130 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 131 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 132 unsigned int q_len; /* events on the queue */ 133 unsigned int max_events; /* maximum events allowed on the list */ 134 /* 135 * Valid fsnotify group priorities. Events are send in order from highest 136 * priority to lowest priority. We default to the lowest priority. 137 */ 138 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 139 #define FS_PRIO_1 1 /* fanotify content based access control */ 140 #define FS_PRIO_2 2 /* fanotify pre-content access */ 141 unsigned int priority; 142 143 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 144 spinlock_t mark_lock; /* protect marks_list */ 145 atomic_t num_marks; /* 1 for each mark and 1 for not being 146 * past the point of no return when freeing 147 * a group */ 148 struct list_head marks_list; /* all inode marks for this group */ 149 150 /* groups can define private fields here or use the void *private */ 151 union { 152 void *private; 153 #ifdef CONFIG_INOTIFY_USER 154 struct inotify_group_private_data { 155 spinlock_t idr_lock; 156 struct idr idr; 157 u32 last_wd; 158 struct fasync_struct *fa; /* async notification */ 159 struct user_struct *user; 160 } inotify_data; 161 #endif 162 #ifdef CONFIG_FANOTIFY 163 struct fanotify_group_private_data { 164 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 165 /* allows a group to block waiting for a userspace response */ 166 struct mutex access_mutex; 167 struct list_head access_list; 168 wait_queue_head_t access_waitq; 169 atomic_t bypass_perm; 170 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 171 int f_flags; 172 unsigned int max_marks; 173 struct user_struct *user; 174 } fanotify_data; 175 #endif /* CONFIG_FANOTIFY */ 176 }; 177 }; 178 179 /* 180 * A single event can be queued in multiple group->notification_lists. 181 * 182 * each group->notification_list will point to an event_holder which in turns points 183 * to the actual event that needs to be sent to userspace. 184 * 185 * Seemed cheaper to create a refcnt'd event and a small holder for every group 186 * than create a different event for every group 187 * 188 */ 189 struct fsnotify_event_holder { 190 struct fsnotify_event *event; 191 struct list_head event_list; 192 }; 193 194 /* 195 * Inotify needs to tack data onto an event. This struct lets us later find the 196 * correct private data of the correct group. 197 */ 198 struct fsnotify_event_private_data { 199 struct fsnotify_group *group; 200 struct list_head event_list; 201 }; 202 203 /* 204 * all of the information about the original object we want to now send to 205 * a group. If you want to carry more info from the accessing task to the 206 * listener this structure is where you need to be adding fields. 207 */ 208 struct fsnotify_event { 209 /* 210 * If we create an event we are also likely going to need a holder 211 * to link to a group. So embed one holder in the event. Means only 212 * one allocation for the common case where we only have one group 213 */ 214 struct fsnotify_event_holder holder; 215 spinlock_t lock; /* protection for the associated event_holder and private_list */ 216 /* to_tell may ONLY be dereferenced during handle_event(). */ 217 struct inode *to_tell; /* either the inode the event happened to or its parent */ 218 /* 219 * depending on the event type we should have either a path or inode 220 * We hold a reference on path, but NOT on inode. Since we have the ref on 221 * the path, it may be dereferenced at any point during this object's 222 * lifetime. That reference is dropped when this object's refcnt hits 223 * 0. If this event contains an inode instead of a path, the inode may 224 * ONLY be used during handle_event(). 225 */ 226 union { 227 struct path path; 228 struct inode *inode; 229 }; 230 /* when calling fsnotify tell it if the data is a path or inode */ 231 #define FSNOTIFY_EVENT_NONE 0 232 #define FSNOTIFY_EVENT_PATH 1 233 #define FSNOTIFY_EVENT_INODE 2 234 int data_type; /* which of the above union we have */ 235 atomic_t refcnt; /* how many groups still are using/need to send this event */ 236 __u32 mask; /* the type of access, bitwise OR for FS_* event types */ 237 238 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ 239 const unsigned char *file_name; 240 size_t name_len; 241 struct pid *tgid; 242 243 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 244 __u32 response; /* userspace answer to question */ 245 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 246 247 struct list_head private_data_list; /* groups can store private data here */ 248 }; 249 250 /* 251 * Inode specific fields in an fsnotify_mark 252 */ 253 struct fsnotify_inode_mark { 254 struct inode *inode; /* inode this mark is associated with */ 255 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */ 256 struct list_head free_i_list; /* tmp list used when freeing this mark */ 257 }; 258 259 /* 260 * Mount point specific fields in an fsnotify_mark 261 */ 262 struct fsnotify_vfsmount_mark { 263 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 264 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */ 265 struct list_head free_m_list; /* tmp list used when freeing this mark */ 266 }; 267 268 /* 269 * a mark is simply an object attached to an in core inode which allows an 270 * fsnotify listener to indicate they are either no longer interested in events 271 * of a type matching mask or only interested in those events. 272 * 273 * these are flushed when an inode is evicted from core and may be flushed 274 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users 275 * (such as dnotify) will flush these when the open fd is closed and not at 276 * inode eviction or modification. 277 */ 278 struct fsnotify_mark { 279 __u32 mask; /* mask this mark is for */ 280 /* we hold ref for each i_list and g_list. also one ref for each 'thing' 281 * in kernel that found and may be using this mark. */ 282 atomic_t refcnt; /* active things looking at this mark */ 283 struct fsnotify_group *group; /* group this mark is for */ 284 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */ 285 spinlock_t lock; /* protect group and inode */ 286 union { 287 struct fsnotify_inode_mark i; 288 struct fsnotify_vfsmount_mark m; 289 }; 290 struct list_head free_g_list; /* tmp list used when freeing this mark */ 291 __u32 ignored_mask; /* events types to ignore */ 292 #define FSNOTIFY_MARK_FLAG_INODE 0x01 293 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 294 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 295 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 296 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10 297 unsigned int flags; /* vfsmount or inode mark? */ 298 struct list_head destroy_list; 299 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 300 }; 301 302 #ifdef CONFIG_FSNOTIFY 303 304 /* called from the vfs helpers */ 305 306 /* main fsnotify call to send events */ 307 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 308 const unsigned char *name, u32 cookie); 309 extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 310 extern void __fsnotify_inode_delete(struct inode *inode); 311 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 312 extern u32 fsnotify_get_cookie(void); 313 314 static inline int fsnotify_inode_watches_children(struct inode *inode) 315 { 316 /* FS_EVENT_ON_CHILD is set if the inode may care */ 317 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 318 return 0; 319 /* this inode might care about child events, does it care about the 320 * specific set of events that can happen on a child? */ 321 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 322 } 323 324 /* 325 * Update the dentry with a flag indicating the interest of its parent to receive 326 * filesystem events when those events happens to this dentry->d_inode. 327 */ 328 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 329 { 330 struct dentry *parent; 331 332 assert_spin_locked(&dentry->d_lock); 333 334 /* 335 * Serialisation of setting PARENT_WATCHED on the dentries is provided 336 * by d_lock. If inotify_inode_watched changes after we have taken 337 * d_lock, the following __fsnotify_update_child_dentry_flags call will 338 * find our entry, so it will spin until we complete here, and update 339 * us with the new state. 340 */ 341 parent = dentry->d_parent; 342 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 343 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 344 else 345 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 346 } 347 348 /* 349 * fsnotify_d_instantiate - instantiate a dentry for inode 350 */ 351 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 352 { 353 if (!inode) 354 return; 355 356 spin_lock(&dentry->d_lock); 357 __fsnotify_update_dcache_flags(dentry); 358 spin_unlock(&dentry->d_lock); 359 } 360 361 /* called from fsnotify listeners, such as fanotify or dnotify */ 362 363 /* get a reference to an existing or create a new group */ 364 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 365 /* drop reference on a group from fsnotify_alloc_group */ 366 extern void fsnotify_put_group(struct fsnotify_group *group); 367 368 /* take a reference to an event */ 369 extern void fsnotify_get_event(struct fsnotify_event *event); 370 extern void fsnotify_put_event(struct fsnotify_event *event); 371 /* find private data previously attached to an event and unlink it */ 372 extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, 373 struct fsnotify_event *event); 374 375 /* attach the event to the group notification queue */ 376 extern struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, 377 struct fsnotify_event *event, 378 struct fsnotify_event_private_data *priv, 379 struct fsnotify_event *(*merge)(struct list_head *, 380 struct fsnotify_event *)); 381 /* true if the group notification queue is empty */ 382 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 383 /* return, but do not dequeue the first event on the notification queue */ 384 extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); 385 /* return AND dequeue the first event on the notification queue */ 386 extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); 387 388 /* functions used to manipulate the marks attached to inodes */ 389 390 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 391 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 392 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 393 extern void fsnotify_recalc_inode_mask(struct inode *inode); 394 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 395 /* find (and take a reference) to a mark associated with group and inode */ 396 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 397 /* find (and take a reference) to a mark associated with group and vfsmount */ 398 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 399 /* copy the values from old into new */ 400 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 401 /* set the ignored_mask of a mark */ 402 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 403 /* set the mask of a mark (might pin the object into memory */ 404 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 405 /* attach the mark to both the group and the inode */ 406 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 407 struct inode *inode, struct vfsmount *mnt, int allow_dups); 408 /* given a mark, flag it to be freed when all references are dropped */ 409 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark); 410 /* run all the marks in a group, and clear all of the vfsmount marks */ 411 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 412 /* run all the marks in a group, and clear all of the inode marks */ 413 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 414 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 415 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 416 /* run all the marks in a group, and flag them to be freed */ 417 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 418 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 419 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 420 extern void fsnotify_unmount_inodes(struct list_head *list); 421 422 /* put here because inotify does some weird stuff when destroying watches */ 423 extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, 424 void *data, int data_is, 425 const unsigned char *name, 426 u32 cookie, gfp_t gfp); 427 428 /* fanotify likes to change events after they are on lists... */ 429 extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event); 430 extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder, 431 struct fsnotify_event *new_event); 432 433 #else 434 435 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 436 const unsigned char *name, u32 cookie) 437 { 438 return 0; 439 } 440 441 static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 442 { 443 return 0; 444 } 445 446 static inline void __fsnotify_inode_delete(struct inode *inode) 447 {} 448 449 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 450 {} 451 452 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 453 {} 454 455 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 456 {} 457 458 static inline u32 fsnotify_get_cookie(void) 459 { 460 return 0; 461 } 462 463 static inline void fsnotify_unmount_inodes(struct list_head *list) 464 {} 465 466 #endif /* CONFIG_FSNOTIFY */ 467 468 #endif /* __KERNEL __ */ 469 470 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 471