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 #include <linux/atomic.h> 19 #include <linux/user_namespace.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 | FS_OPEN_PERM | FS_ACCESS_PERM) 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 struct fsnotify_fname; 83 struct fsnotify_iter_info; 84 85 /* 86 * Each group much define these ops. The fsnotify infrastructure will call 87 * these operations for each relevant group. 88 * 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, const void *data, int data_type, 102 const unsigned char *file_name, u32 cookie, 103 struct fsnotify_iter_info *iter_info); 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)(struct fsnotify_event *event); 107 /* called on final put+free to free memory */ 108 void (*free_mark)(struct fsnotify_mark *mark); 109 }; 110 111 /* 112 * all of the information about the original object we want to now send to 113 * a group. If you want to carry more info from the accessing task to the 114 * listener this structure is where you need to be adding fields. 115 */ 116 struct fsnotify_event { 117 struct list_head list; 118 /* inode may ONLY be dereferenced during handle_event(). */ 119 struct inode *inode; /* either the inode the event happened to or its parent */ 120 u32 mask; /* the type of access, bitwise OR for FS_* event types */ 121 }; 122 123 /* 124 * A group is a "thing" that wants to receive notification about filesystem 125 * events. The mask holds the subset of event types this group cares about. 126 * refcnt on a group is up to the implementor and at any moment if it goes 0 127 * everything will be cleaned up. 128 */ 129 struct fsnotify_group { 130 /* 131 * How the refcnt is used is up to each group. When the refcnt hits 0 132 * fsnotify will clean up all of the resources associated with this group. 133 * As an example, the dnotify group will always have a refcnt=1 and that 134 * will never change. Inotify, on the other hand, has a group per 135 * inotify_init() and the refcnt will hit 0 only when that fd has been 136 * closed. 137 */ 138 atomic_t refcnt; /* things with interest in this group */ 139 140 const struct fsnotify_ops *ops; /* how this group handles things */ 141 142 /* needed to send notification to userspace */ 143 spinlock_t notification_lock; /* protect the notification_list */ 144 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 145 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 146 unsigned int q_len; /* events on the queue */ 147 unsigned int max_events; /* maximum events allowed on the list */ 148 /* 149 * Valid fsnotify group priorities. Events are send in order from highest 150 * priority to lowest priority. We default to the lowest priority. 151 */ 152 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 153 #define FS_PRIO_1 1 /* fanotify content based access control */ 154 #define FS_PRIO_2 2 /* fanotify pre-content access */ 155 unsigned int priority; 156 bool shutdown; /* group is being shut down, don't queue more events */ 157 158 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 159 struct mutex mark_mutex; /* protect marks_list */ 160 atomic_t num_marks; /* 1 for each mark and 1 for not being 161 * past the point of no return when freeing 162 * a group */ 163 struct list_head marks_list; /* all inode marks for this group */ 164 165 struct fasync_struct *fsn_fa; /* async notification */ 166 167 struct fsnotify_event *overflow_event; /* Event we queue when the 168 * notification list is too 169 * full */ 170 atomic_t user_waits; /* Number of tasks waiting for user 171 * response */ 172 173 /* groups can define private fields here or use the void *private */ 174 union { 175 void *private; 176 #ifdef CONFIG_INOTIFY_USER 177 struct inotify_group_private_data { 178 spinlock_t idr_lock; 179 struct idr idr; 180 struct ucounts *ucounts; 181 } inotify_data; 182 #endif 183 #ifdef CONFIG_FANOTIFY 184 struct fanotify_group_private_data { 185 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 186 /* allows a group to block waiting for a userspace response */ 187 struct list_head access_list; 188 wait_queue_head_t access_waitq; 189 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 190 int f_flags; 191 unsigned int max_marks; 192 struct user_struct *user; 193 } fanotify_data; 194 #endif /* CONFIG_FANOTIFY */ 195 }; 196 }; 197 198 /* when calling fsnotify tell it if the data is a path or inode */ 199 #define FSNOTIFY_EVENT_NONE 0 200 #define FSNOTIFY_EVENT_PATH 1 201 #define FSNOTIFY_EVENT_INODE 2 202 203 /* 204 * Inode / vfsmount point to this structure which tracks all marks attached to 205 * the inode / vfsmount. The reference to inode / vfsmount is held by this 206 * structure. We destroy this structure when there are no more marks attached 207 * to it. The structure is protected by fsnotify_mark_srcu. 208 */ 209 struct fsnotify_mark_connector { 210 spinlock_t lock; 211 #define FSNOTIFY_OBJ_TYPE_INODE 0x01 212 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT 0x02 213 #define FSNOTIFY_OBJ_ALL_TYPES (FSNOTIFY_OBJ_TYPE_INODE | \ 214 FSNOTIFY_OBJ_TYPE_VFSMOUNT) 215 unsigned int flags; /* Type of object [lock] */ 216 union { /* Object pointer [lock] */ 217 struct inode *inode; 218 struct vfsmount *mnt; 219 }; 220 union { 221 struct hlist_head list; 222 /* Used listing heads to free after srcu period expires */ 223 struct fsnotify_mark_connector *destroy_next; 224 }; 225 }; 226 227 /* 228 * A mark is simply an object attached to an in core inode which allows an 229 * fsnotify listener to indicate they are either no longer interested in events 230 * of a type matching mask or only interested in those events. 231 * 232 * These are flushed when an inode is evicted from core and may be flushed 233 * when the inode is modified (as seen by fsnotify_access). Some fsnotify 234 * users (such as dnotify) will flush these when the open fd is closed and not 235 * at inode eviction or modification. 236 * 237 * Text in brackets is showing the lock(s) protecting modifications of a 238 * particular entry. obj_lock means either inode->i_lock or 239 * mnt->mnt_root->d_lock depending on the mark type. 240 */ 241 struct fsnotify_mark { 242 /* Mask this mark is for [mark->lock, group->mark_mutex] */ 243 __u32 mask; 244 /* We hold one for presence in g_list. Also one ref for each 'thing' 245 * in kernel that found and may be using this mark. */ 246 atomic_t refcnt; 247 /* Group this mark is for. Set on mark creation, stable until last ref 248 * is dropped */ 249 struct fsnotify_group *group; 250 /* List of marks by group->i_fsnotify_marks. Also reused for queueing 251 * mark into destroy_list when it's waiting for the end of SRCU period 252 * before it can be freed. [group->mark_mutex] */ 253 struct list_head g_list; 254 /* Protects inode / mnt pointers, flags, masks */ 255 spinlock_t lock; 256 /* List of marks for inode / vfsmount [connector->lock, mark ref] */ 257 struct hlist_node obj_list; 258 /* Head of list of marks for an object [mark ref] */ 259 struct fsnotify_mark_connector *connector; 260 /* Events types to ignore [mark->lock, group->mark_mutex] */ 261 __u32 ignored_mask; 262 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x01 263 #define FSNOTIFY_MARK_FLAG_ALIVE 0x02 264 #define FSNOTIFY_MARK_FLAG_ATTACHED 0x04 265 unsigned int flags; /* flags [mark->lock] */ 266 }; 267 268 #ifdef CONFIG_FSNOTIFY 269 270 /* called from the vfs helpers */ 271 272 /* main fsnotify call to send events */ 273 extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, 274 const unsigned char *name, u32 cookie); 275 extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask); 276 extern void __fsnotify_inode_delete(struct inode *inode); 277 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 278 extern u32 fsnotify_get_cookie(void); 279 280 static inline int fsnotify_inode_watches_children(struct inode *inode) 281 { 282 /* FS_EVENT_ON_CHILD is set if the inode may care */ 283 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 284 return 0; 285 /* this inode might care about child events, does it care about the 286 * specific set of events that can happen on a child? */ 287 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 288 } 289 290 /* 291 * Update the dentry with a flag indicating the interest of its parent to receive 292 * filesystem events when those events happens to this dentry->d_inode. 293 */ 294 static inline void fsnotify_update_flags(struct dentry *dentry) 295 { 296 assert_spin_locked(&dentry->d_lock); 297 298 /* 299 * Serialisation of setting PARENT_WATCHED on the dentries is provided 300 * by d_lock. If inotify_inode_watched changes after we have taken 301 * d_lock, the following __fsnotify_update_child_dentry_flags call will 302 * find our entry, so it will spin until we complete here, and update 303 * us with the new state. 304 */ 305 if (fsnotify_inode_watches_children(dentry->d_parent->d_inode)) 306 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 307 else 308 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 309 } 310 311 /* called from fsnotify listeners, such as fanotify or dnotify */ 312 313 /* create a new group */ 314 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 315 /* get reference to a group */ 316 extern void fsnotify_get_group(struct fsnotify_group *group); 317 /* drop reference on a group from fsnotify_alloc_group */ 318 extern void fsnotify_put_group(struct fsnotify_group *group); 319 /* group destruction begins, stop queuing new events */ 320 extern void fsnotify_group_stop_queueing(struct fsnotify_group *group); 321 /* destroy group */ 322 extern void fsnotify_destroy_group(struct fsnotify_group *group); 323 /* fasync handler function */ 324 extern int fsnotify_fasync(int fd, struct file *file, int on); 325 /* Free event from memory */ 326 extern void fsnotify_destroy_event(struct fsnotify_group *group, 327 struct fsnotify_event *event); 328 /* attach the event to the group notification queue */ 329 extern int fsnotify_add_event(struct fsnotify_group *group, 330 struct fsnotify_event *event, 331 int (*merge)(struct list_head *, 332 struct fsnotify_event *)); 333 /* true if the group notification queue is empty */ 334 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 335 /* return, but do not dequeue the first event on the notification queue */ 336 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 337 /* return AND dequeue the first event on the notification queue */ 338 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 339 340 /* functions used to manipulate the marks attached to inodes */ 341 342 /* Calculate mask of events for a list of marks */ 343 extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn); 344 extern void fsnotify_init_mark(struct fsnotify_mark *mark, 345 struct fsnotify_group *group); 346 /* Find mark belonging to given group in the list of marks */ 347 extern struct fsnotify_mark *fsnotify_find_mark( 348 struct fsnotify_mark_connector __rcu **connp, 349 struct fsnotify_group *group); 350 /* attach the mark to the inode or vfsmount */ 351 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct inode *inode, 352 struct vfsmount *mnt, int allow_dups); 353 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, 354 struct inode *inode, struct vfsmount *mnt, int allow_dups); 355 /* given a group and a mark, flag mark to be freed when all references are dropped */ 356 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 357 struct fsnotify_group *group); 358 /* detach mark from inode / mount list, group list, drop inode reference */ 359 extern void fsnotify_detach_mark(struct fsnotify_mark *mark); 360 /* free mark */ 361 extern void fsnotify_free_mark(struct fsnotify_mark *mark); 362 /* run all the marks in a group, and clear all of the marks attached to given object type */ 363 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group, unsigned int type); 364 /* run all the marks in a group, and clear all of the vfsmount marks */ 365 static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group) 366 { 367 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT); 368 } 369 /* run all the marks in a group, and clear all of the inode marks */ 370 static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group) 371 { 372 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE); 373 } 374 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 375 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 376 extern void fsnotify_unmount_inodes(struct super_block *sb); 377 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info); 378 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info); 379 380 /* put here because inotify does some weird stuff when destroying watches */ 381 extern void fsnotify_init_event(struct fsnotify_event *event, 382 struct inode *to_tell, u32 mask); 383 384 #else 385 386 static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, 387 const unsigned char *name, u32 cookie) 388 { 389 return 0; 390 } 391 392 static inline int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask) 393 { 394 return 0; 395 } 396 397 static inline void __fsnotify_inode_delete(struct inode *inode) 398 {} 399 400 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 401 {} 402 403 static inline void fsnotify_update_flags(struct dentry *dentry) 404 {} 405 406 static inline u32 fsnotify_get_cookie(void) 407 { 408 return 0; 409 } 410 411 static inline void fsnotify_unmount_inodes(struct super_block *sb) 412 {} 413 414 #endif /* CONFIG_FSNOTIFY */ 415 416 #endif /* __KERNEL __ */ 417 418 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 419