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 spinlock_t access_lock; 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 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 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 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 parent = dentry->d_parent; 290 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 291 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 292 else 293 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 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_event(struct fsnotify_group *group, 326 struct fsnotify_event *event, 327 int (*merge)(struct list_head *, 328 struct fsnotify_event *)); 329 /* Remove passed event from groups notification queue */ 330 extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event); 331 /* true if the group notification queue is empty */ 332 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 333 /* return, but do not dequeue the first event on the notification queue */ 334 extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 335 /* return AND dequeue the first event on the notification queue */ 336 extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 337 338 /* functions used to manipulate the marks attached to inodes */ 339 340 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 341 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 342 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 343 extern void fsnotify_recalc_inode_mask(struct inode *inode); 344 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 345 /* find (and take a reference) to a mark associated with group and inode */ 346 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 347 /* find (and take a reference) to a mark associated with group and vfsmount */ 348 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 349 /* copy the values from old into new */ 350 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 351 /* set the ignored_mask of a mark */ 352 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 353 /* set the mask of a mark (might pin the object into memory */ 354 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 355 /* attach the mark to both the group and the inode */ 356 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 357 struct inode *inode, struct vfsmount *mnt, int allow_dups); 358 extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, 359 struct inode *inode, struct vfsmount *mnt, int allow_dups); 360 /* given a group and a mark, flag mark to be freed when all references are dropped */ 361 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 362 struct fsnotify_group *group); 363 extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark, 364 struct fsnotify_group *group); 365 /* run all the marks in a group, and clear all of the vfsmount marks */ 366 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 367 /* run all the marks in a group, and clear all of the inode marks */ 368 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 369 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 370 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 371 /* run all the marks in a group, and flag them to be freed */ 372 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 373 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 374 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 375 extern void fsnotify_unmount_inodes(struct list_head *list); 376 377 /* put here because inotify does some weird stuff when destroying watches */ 378 extern void fsnotify_init_event(struct fsnotify_event *event, 379 struct inode *to_tell, u32 mask); 380 381 #else 382 383 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 384 const unsigned char *name, u32 cookie) 385 { 386 return 0; 387 } 388 389 static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 390 { 391 return 0; 392 } 393 394 static inline void __fsnotify_inode_delete(struct inode *inode) 395 {} 396 397 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 398 {} 399 400 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 401 {} 402 403 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 404 {} 405 406 static inline u32 fsnotify_get_cookie(void) 407 { 408 return 0; 409 } 410 411 static inline void fsnotify_unmount_inodes(struct list_head *list) 412 {} 413 414 #endif /* CONFIG_FSNOTIFY */ 415 416 #endif /* __KERNEL __ */ 417 418 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 419