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 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 * handle_event - main call for a group to handle an fs event 88 * free_group_priv - called when a group refcnt hits 0 to clean up the private union 89 * freeing_mark - called when a mark is being destroyed for some reason. The group 90 * MUST be holding a reference on each mark and that reference must be 91 * dropped in this function. inotify uses this function to send 92 * userspace messages that marks have been removed. 93 */ 94 struct fsnotify_ops { 95 int (*handle_event)(struct fsnotify_group *group, 96 struct inode *inode, 97 struct fsnotify_mark *inode_mark, 98 struct fsnotify_mark *vfsmount_mark, 99 u32 mask, void *data, int data_type, 100 const unsigned char *file_name, u32 cookie); 101 void (*free_group_priv)(struct fsnotify_group *group); 102 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 103 void (*free_event)(struct fsnotify_event *event); 104 }; 105 106 /* 107 * all of the information about the original object we want to now send to 108 * a group. If you want to carry more info from the accessing task to the 109 * listener this structure is where you need to be adding fields. 110 */ 111 struct fsnotify_event { 112 struct list_head list; 113 /* inode may ONLY be dereferenced during handle_event(). */ 114 struct inode *inode; /* either the inode the event happened to or its parent */ 115 u32 mask; /* the type of access, bitwise OR for FS_* event types */ 116 }; 117 118 /* 119 * A group is a "thing" that wants to receive notification about filesystem 120 * events. The mask holds the subset of event types this group cares about. 121 * refcnt on a group is up to the implementor and at any moment if it goes 0 122 * everything will be cleaned up. 123 */ 124 struct fsnotify_group { 125 /* 126 * How the refcnt is used is up to each group. When the refcnt hits 0 127 * fsnotify will clean up all of the resources associated with this group. 128 * As an example, the dnotify group will always have a refcnt=1 and that 129 * will never change. Inotify, on the other hand, has a group per 130 * inotify_init() and the refcnt will hit 0 only when that fd has been 131 * closed. 132 */ 133 atomic_t refcnt; /* things with interest in this group */ 134 135 const struct fsnotify_ops *ops; /* how this group handles things */ 136 137 /* needed to send notification to userspace */ 138 struct mutex notification_mutex; /* protect the notification_list */ 139 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 140 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 141 unsigned int q_len; /* events on the queue */ 142 unsigned int max_events; /* maximum events allowed on the list */ 143 /* 144 * Valid fsnotify group priorities. Events are send in order from highest 145 * priority to lowest priority. We default to the lowest priority. 146 */ 147 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 148 #define FS_PRIO_1 1 /* fanotify content based access control */ 149 #define FS_PRIO_2 2 /* fanotify pre-content access */ 150 unsigned int priority; 151 152 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 153 struct mutex mark_mutex; /* protect marks_list */ 154 atomic_t num_marks; /* 1 for each mark and 1 for not being 155 * past the point of no return when freeing 156 * a group */ 157 struct list_head marks_list; /* all inode marks for this group */ 158 159 struct fasync_struct *fsn_fa; /* async notification */ 160 161 struct fsnotify_event *overflow_event; /* Event we queue when the 162 * notification list is too 163 * full */ 164 165 /* groups can define private fields here or use the void *private */ 166 union { 167 void *private; 168 #ifdef CONFIG_INOTIFY_USER 169 struct inotify_group_private_data { 170 spinlock_t idr_lock; 171 struct idr idr; 172 struct user_struct *user; 173 } inotify_data; 174 #endif 175 #ifdef CONFIG_FANOTIFY 176 struct fanotify_group_private_data { 177 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 178 /* allows a group to block waiting for a userspace response */ 179 spinlock_t access_lock; 180 struct list_head access_list; 181 wait_queue_head_t access_waitq; 182 atomic_t bypass_perm; 183 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 184 int f_flags; 185 unsigned int max_marks; 186 struct user_struct *user; 187 } fanotify_data; 188 #endif /* CONFIG_FANOTIFY */ 189 }; 190 }; 191 192 /* when calling fsnotify tell it if the data is a path or inode */ 193 #define FSNOTIFY_EVENT_NONE 0 194 #define FSNOTIFY_EVENT_PATH 1 195 #define FSNOTIFY_EVENT_INODE 2 196 197 /* 198 * a mark is simply an object attached to an in core inode which allows an 199 * fsnotify listener to indicate they are either no longer interested in events 200 * of a type matching mask or only interested in those events. 201 * 202 * these are flushed when an inode is evicted from core and may be flushed 203 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users 204 * (such as dnotify) will flush these when the open fd is closed and not at 205 * inode eviction or modification. 206 */ 207 struct fsnotify_mark { 208 __u32 mask; /* mask this mark is for */ 209 /* we hold ref for each i_list and g_list. also one ref for each 'thing' 210 * in kernel that found and may be using this mark. */ 211 atomic_t refcnt; /* active things looking at this mark */ 212 struct fsnotify_group *group; /* group this mark is for */ 213 struct list_head g_list; /* list of marks by group->i_fsnotify_marks 214 * Also reused for queueing mark into 215 * destroy_list when it's waiting for 216 * the end of SRCU period before it can 217 * be freed */ 218 spinlock_t lock; /* protect group and inode */ 219 struct hlist_node obj_list; /* list of marks for inode / vfsmount */ 220 struct list_head free_list; /* tmp list used when freeing this mark */ 221 union { 222 struct inode *inode; /* inode this mark is associated with */ 223 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 224 }; 225 __u32 ignored_mask; /* events types to ignore */ 226 #define FSNOTIFY_MARK_FLAG_INODE 0x01 227 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 228 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 229 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 230 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10 231 unsigned int flags; /* vfsmount or inode mark? */ 232 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 233 }; 234 235 #ifdef CONFIG_FSNOTIFY 236 237 /* called from the vfs helpers */ 238 239 /* main fsnotify call to send events */ 240 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 241 const unsigned char *name, u32 cookie); 242 extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 243 extern void __fsnotify_inode_delete(struct inode *inode); 244 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 245 extern u32 fsnotify_get_cookie(void); 246 247 static inline int fsnotify_inode_watches_children(struct inode *inode) 248 { 249 /* FS_EVENT_ON_CHILD is set if the inode may care */ 250 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 251 return 0; 252 /* this inode might care about child events, does it care about the 253 * specific set of events that can happen on a child? */ 254 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 255 } 256 257 /* 258 * Update the dentry with a flag indicating the interest of its parent to receive 259 * filesystem events when those events happens to this dentry->d_inode. 260 */ 261 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 262 { 263 struct dentry *parent; 264 265 assert_spin_locked(&dentry->d_lock); 266 267 /* 268 * Serialisation of setting PARENT_WATCHED on the dentries is provided 269 * by d_lock. If inotify_inode_watched changes after we have taken 270 * d_lock, the following __fsnotify_update_child_dentry_flags call will 271 * find our entry, so it will spin until we complete here, and update 272 * us with the new state. 273 */ 274 parent = dentry->d_parent; 275 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 276 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 277 else 278 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 279 } 280 281 /* 282 * fsnotify_d_instantiate - instantiate a dentry for inode 283 */ 284 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 285 { 286 if (!inode) 287 return; 288 289 spin_lock(&dentry->d_lock); 290 __fsnotify_update_dcache_flags(dentry); 291 spin_unlock(&dentry->d_lock); 292 } 293 294 /* called from fsnotify listeners, such as fanotify or dnotify */ 295 296 /* create a new group */ 297 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 298 /* get reference to a group */ 299 extern void fsnotify_get_group(struct fsnotify_group *group); 300 /* drop reference on a group from fsnotify_alloc_group */ 301 extern void fsnotify_put_group(struct fsnotify_group *group); 302 /* destroy group */ 303 extern void fsnotify_destroy_group(struct fsnotify_group *group); 304 /* fasync handler function */ 305 extern int fsnotify_fasync(int fd, struct file *file, int on); 306 /* Free event from memory */ 307 extern void fsnotify_destroy_event(struct fsnotify_group *group, 308 struct fsnotify_event *event); 309 /* attach the event to the group notification queue */ 310 extern int fsnotify_add_event(struct fsnotify_group *group, 311 struct fsnotify_event *event, 312 int (*merge)(struct list_head *, 313 struct fsnotify_event *)); 314 /* Remove passed event from groups notification queue */ 315 extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event); 316 /* true if the group notification queue is empty */ 317 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 318 /* return, but do not dequeue the first event on the notification queue */ 319 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 320 /* return AND dequeue the first event on the notification queue */ 321 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 322 323 /* functions used to manipulate the marks attached to inodes */ 324 325 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 326 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 327 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 328 extern void fsnotify_recalc_inode_mask(struct inode *inode); 329 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 330 /* find (and take a reference) to a mark associated with group and inode */ 331 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 332 /* find (and take a reference) to a mark associated with group and vfsmount */ 333 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 334 /* copy the values from old into new */ 335 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 336 /* set the ignored_mask of a mark */ 337 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 338 /* set the mask of a mark (might pin the object into memory */ 339 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 340 /* attach the mark to both the group and the inode */ 341 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 342 struct inode *inode, struct vfsmount *mnt, int allow_dups); 343 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, 344 struct inode *inode, struct vfsmount *mnt, int allow_dups); 345 /* given a group and a mark, flag mark to be freed when all references are dropped */ 346 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 347 struct fsnotify_group *group); 348 extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark, 349 struct fsnotify_group *group); 350 /* run all the marks in a group, and clear all of the vfsmount marks */ 351 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 352 /* run all the marks in a group, and clear all of the inode marks */ 353 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 354 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 355 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 356 /* run all the marks in a group, and flag them to be freed */ 357 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 358 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 359 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 360 extern void fsnotify_unmount_inodes(struct list_head *list); 361 362 /* put here because inotify does some weird stuff when destroying watches */ 363 extern void fsnotify_init_event(struct fsnotify_event *event, 364 struct inode *to_tell, u32 mask); 365 366 #else 367 368 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 369 const unsigned char *name, u32 cookie) 370 { 371 return 0; 372 } 373 374 static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 375 { 376 return 0; 377 } 378 379 static inline void __fsnotify_inode_delete(struct inode *inode) 380 {} 381 382 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 383 {} 384 385 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 386 {} 387 388 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 389 {} 390 391 static inline u32 fsnotify_get_cookie(void) 392 { 393 return 0; 394 } 395 396 static inline void fsnotify_unmount_inodes(struct list_head *list) 397 {} 398 399 #endif /* CONFIG_FSNOTIFY */ 400 401 #endif /* __KERNEL __ */ 402 403 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 404