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 77struct fsnotify_group; 78struct fsnotify_event; 79struct fsnotify_mark; 80struct fsnotify_event_private_data; 81struct 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 */ 96struct 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 */ 113struct 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 */ 126struct 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 * a mark is simply an object attached to an in core inode which allows an 201 * fsnotify listener to indicate they are either no longer interested in events 202 * of a type matching mask or only interested in those events. 203 * 204 * these are flushed when an inode is evicted from core and may be flushed 205 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users 206 * (such as dnotify) will flush these when the open fd is closed and not at 207 * inode eviction or modification. 208 */ 209struct fsnotify_mark { 210 __u32 mask; /* mask this mark is for */ 211 /* we hold ref for each i_list and g_list. also one ref for each 'thing' 212 * in kernel that found and may be using this mark. */ 213 atomic_t refcnt; /* active things looking at this mark */ 214 struct fsnotify_group *group; /* group this mark is for */ 215 struct list_head g_list; /* list of marks by group->i_fsnotify_marks 216 * Also reused for queueing mark into 217 * destroy_list when it's waiting for 218 * the end of SRCU period before it can 219 * be freed */ 220 spinlock_t lock; /* protect group and inode */ 221 struct hlist_node obj_list; /* list of marks for inode / vfsmount */ 222 struct list_head free_list; /* tmp list used when freeing this mark */ 223 union { 224 struct inode *inode; /* inode this mark is associated with */ 225 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 226 }; 227 __u32 ignored_mask; /* events types to ignore */ 228#define FSNOTIFY_MARK_FLAG_INODE 0x01 229#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 230#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 231#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 232#define FSNOTIFY_MARK_FLAG_ALIVE 0x10 233 unsigned int flags; /* vfsmount or inode mark? */ 234 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 235}; 236 237#ifdef CONFIG_FSNOTIFY 238 239/* called from the vfs helpers */ 240 241/* main fsnotify call to send events */ 242extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 243 const unsigned char *name, u32 cookie); 244extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 245extern void __fsnotify_inode_delete(struct inode *inode); 246extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 247extern u32 fsnotify_get_cookie(void); 248 249static inline int fsnotify_inode_watches_children(struct inode *inode) 250{ 251 /* FS_EVENT_ON_CHILD is set if the inode may care */ 252 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 253 return 0; 254 /* this inode might care about child events, does it care about the 255 * specific set of events that can happen on a child? */ 256 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 257} 258 259/* 260 * Update the dentry with a flag indicating the interest of its parent to receive 261 * filesystem events when those events happens to this dentry->d_inode. 262 */ 263static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 264{ 265 struct dentry *parent; 266 267 assert_spin_locked(&dentry->d_lock); 268 269 /* 270 * Serialisation of setting PARENT_WATCHED on the dentries is provided 271 * by d_lock. If inotify_inode_watched changes after we have taken 272 * d_lock, the following __fsnotify_update_child_dentry_flags call will 273 * find our entry, so it will spin until we complete here, and update 274 * us with the new state. 275 */ 276 parent = dentry->d_parent; 277 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 278 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 279 else 280 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 281} 282 283/* 284 * fsnotify_d_instantiate - instantiate a dentry for inode 285 */ 286static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 287{ 288 if (!inode) 289 return; 290 291 spin_lock(&dentry->d_lock); 292 __fsnotify_update_dcache_flags(dentry); 293 spin_unlock(&dentry->d_lock); 294} 295 296/* called from fsnotify listeners, such as fanotify or dnotify */ 297 298/* create a new group */ 299extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 300/* get reference to a group */ 301extern void fsnotify_get_group(struct fsnotify_group *group); 302/* drop reference on a group from fsnotify_alloc_group */ 303extern void fsnotify_put_group(struct fsnotify_group *group); 304/* destroy group */ 305extern void fsnotify_destroy_group(struct fsnotify_group *group); 306/* fasync handler function */ 307extern int fsnotify_fasync(int fd, struct file *file, int on); 308/* Free event from memory */ 309extern void fsnotify_destroy_event(struct fsnotify_group *group, 310 struct fsnotify_event *event); 311/* attach the event to the group notification queue */ 312extern int fsnotify_add_event(struct fsnotify_group *group, 313 struct fsnotify_event *event, 314 int (*merge)(struct list_head *, 315 struct fsnotify_event *)); 316/* Remove passed event from groups notification queue */ 317extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event); 318/* true if the group notification queue is empty */ 319extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 320/* return, but do not dequeue the first event on the notification queue */ 321extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 322/* return AND dequeue the first event on the notification queue */ 323extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 324 325/* functions used to manipulate the marks attached to inodes */ 326 327/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 328extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 329/* run all marks associated with an inode and update inode->i_fsnotify_mask */ 330extern void fsnotify_recalc_inode_mask(struct inode *inode); 331extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 332/* find (and take a reference) to a mark associated with group and inode */ 333extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 334/* find (and take a reference) to a mark associated with group and vfsmount */ 335extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 336/* copy the values from old into new */ 337extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 338/* set the ignored_mask of a mark */ 339extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 340/* set the mask of a mark (might pin the object into memory */ 341extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 342/* attach the mark to both the group and the inode */ 343extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 344 struct inode *inode, struct vfsmount *mnt, int allow_dups); 345extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group, 346 struct inode *inode, struct vfsmount *mnt, int allow_dups); 347/* given a group and a mark, flag mark to be freed when all references are dropped */ 348extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 349 struct fsnotify_group *group); 350extern void fsnotify_destroy_mark_locked(struct fsnotify_mark *mark, 351 struct fsnotify_group *group); 352/* run all the marks in a group, and clear all of the vfsmount marks */ 353extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 354/* run all the marks in a group, and clear all of the inode marks */ 355extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 356/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 357extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 358/* run all the marks in a group, and flag them to be freed */ 359extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 360extern void fsnotify_get_mark(struct fsnotify_mark *mark); 361extern void fsnotify_put_mark(struct fsnotify_mark *mark); 362extern void fsnotify_unmount_inodes(struct list_head *list); 363 364/* put here because inotify does some weird stuff when destroying watches */ 365extern void fsnotify_init_event(struct fsnotify_event *event, 366 struct inode *to_tell, u32 mask); 367 368#else 369 370static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 371 const unsigned char *name, u32 cookie) 372{ 373 return 0; 374} 375 376static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 377{ 378 return 0; 379} 380 381static inline void __fsnotify_inode_delete(struct inode *inode) 382{} 383 384static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 385{} 386 387static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 388{} 389 390static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 391{} 392 393static inline u32 fsnotify_get_cookie(void) 394{ 395 return 0; 396} 397 398static inline void fsnotify_unmount_inodes(struct list_head *list) 399{} 400 401#endif /* CONFIG_FSNOTIFY */ 402 403#endif /* __KERNEL __ */ 404 405#endif /* __LINUX_FSNOTIFY_BACKEND_H */ 406