1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * Filesystem access notification for Linux 4 * 5 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> 6 */ 7 8#ifndef __LINUX_FSNOTIFY_BACKEND_H 9#define __LINUX_FSNOTIFY_BACKEND_H 10 11#ifdef __KERNEL__ 12 13#include <linux/idr.h> /* inotify uses this */ 14#include <linux/fs.h> /* struct inode */ 15#include <linux/list.h> 16#include <linux/path.h> /* struct path */ 17#include <linux/spinlock.h> 18#include <linux/types.h> 19#include <linux/atomic.h> 20#include <linux/user_namespace.h> 21#include <linux/refcount.h> 22#include <linux/mempool.h> 23#include <linux/sched/mm.h> 24 25/* 26 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily 27 * convert between them. dnotify only needs conversion at watch creation 28 * so no perf loss there. fanotify isn't defined yet, so it can use the 29 * wholes if it needs more events. 30 */ 31#define FS_ACCESS 0x00000001 /* File was accessed */ 32#define FS_MODIFY 0x00000002 /* File was modified */ 33#define FS_ATTRIB 0x00000004 /* Metadata changed */ 34#define FS_CLOSE_WRITE 0x00000008 /* Writable file was closed */ 35#define FS_CLOSE_NOWRITE 0x00000010 /* Unwritable file closed */ 36#define FS_OPEN 0x00000020 /* File was opened */ 37#define FS_MOVED_FROM 0x00000040 /* File was moved from X */ 38#define FS_MOVED_TO 0x00000080 /* File was moved to Y */ 39#define FS_CREATE 0x00000100 /* Subfile was created */ 40#define FS_DELETE 0x00000200 /* Subfile was deleted */ 41#define FS_DELETE_SELF 0x00000400 /* Self was deleted */ 42#define FS_MOVE_SELF 0x00000800 /* Self was moved */ 43#define FS_OPEN_EXEC 0x00001000 /* File was opened for exec */ 44 45#define FS_UNMOUNT 0x00002000 /* inode on umount fs */ 46#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */ 47#define FS_ERROR 0x00008000 /* Filesystem Error (fanotify) */ 48 49/* 50 * FS_IN_IGNORED overloads FS_ERROR. It is only used internally by inotify 51 * which does not support FS_ERROR. 52 */ 53#define FS_IN_IGNORED 0x00008000 /* last inotify event here */ 54 55#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */ 56#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */ 57#define FS_OPEN_EXEC_PERM 0x00040000 /* open/exec event in a permission hook */ 58 59/* 60 * Set on inode mark that cares about things that happen to its children. 61 * Always set for dnotify and inotify. 62 * Set on inode/sb/mount marks that care about parent/name info. 63 */ 64#define FS_EVENT_ON_CHILD 0x08000000 65 66#define FS_RENAME 0x10000000 /* File was renamed */ 67#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ 68#define FS_ISDIR 0x40000000 /* event occurred against dir */ 69 70#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 71 72/* 73 * Directory entry modification events - reported only to directory 74 * where entry is modified and not to a watching parent. 75 * The watching parent may get an FS_ATTRIB|FS_EVENT_ON_CHILD event 76 * when a directory entry inside a child subdir changes. 77 */ 78#define ALL_FSNOTIFY_DIRENT_EVENTS (FS_CREATE | FS_DELETE | FS_MOVE | FS_RENAME) 79 80#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \ 81 FS_OPEN_EXEC_PERM) 82 83/* 84 * This is a list of all events that may get sent to a parent that is watching 85 * with flag FS_EVENT_ON_CHILD based on fs event on a child of that directory. 86 */ 87#define FS_EVENTS_POSS_ON_CHILD (ALL_FSNOTIFY_PERM_EVENTS | \ 88 FS_ACCESS | FS_MODIFY | FS_ATTRIB | \ 89 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | \ 90 FS_OPEN | FS_OPEN_EXEC) 91 92/* 93 * This is a list of all events that may get sent with the parent inode as the 94 * @to_tell argument of fsnotify(). 95 * It may include events that can be sent to an inode/sb/mount mark, but cannot 96 * be sent to a parent watching children. 97 */ 98#define FS_EVENTS_POSS_TO_PARENT (FS_EVENTS_POSS_ON_CHILD) 99 100/* Events that can be reported to backends */ 101#define ALL_FSNOTIFY_EVENTS (ALL_FSNOTIFY_DIRENT_EVENTS | \ 102 FS_EVENTS_POSS_ON_CHILD | \ 103 FS_DELETE_SELF | FS_MOVE_SELF | \ 104 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \ 105 FS_ERROR) 106 107/* Extra flags that may be reported with event or control handling of events */ 108#define ALL_FSNOTIFY_FLAGS (FS_ISDIR | FS_EVENT_ON_CHILD | FS_DN_MULTISHOT) 109 110#define ALL_FSNOTIFY_BITS (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS) 111 112struct fsnotify_group; 113struct fsnotify_event; 114struct fsnotify_mark; 115struct fsnotify_event_private_data; 116struct fsnotify_fname; 117struct fsnotify_iter_info; 118 119struct mem_cgroup; 120 121/* 122 * Each group much define these ops. The fsnotify infrastructure will call 123 * these operations for each relevant group. 124 * 125 * handle_event - main call for a group to handle an fs event 126 * @group: group to notify 127 * @mask: event type and flags 128 * @data: object that event happened on 129 * @data_type: type of object for fanotify_data_XXX() accessors 130 * @dir: optional directory associated with event - 131 * if @file_name is not NULL, this is the directory that 132 * @file_name is relative to 133 * @file_name: optional file name associated with event 134 * @cookie: inotify rename cookie 135 * @iter_info: array of marks from this group that are interested in the event 136 * 137 * handle_inode_event - simple variant of handle_event() for groups that only 138 * have inode marks and don't have ignore mask 139 * @mark: mark to notify 140 * @mask: event type and flags 141 * @inode: inode that event happened on 142 * @dir: optional directory associated with event - 143 * if @file_name is not NULL, this is the directory that 144 * @file_name is relative to. 145 * Either @inode or @dir must be non-NULL. 146 * @file_name: optional file name associated with event 147 * @cookie: inotify rename cookie 148 * 149 * free_group_priv - called when a group refcnt hits 0 to clean up the private union 150 * freeing_mark - called when a mark is being destroyed for some reason. The group 151 * MUST be holding a reference on each mark and that reference must be 152 * dropped in this function. inotify uses this function to send 153 * userspace messages that marks have been removed. 154 */ 155struct fsnotify_ops { 156 int (*handle_event)(struct fsnotify_group *group, u32 mask, 157 const void *data, int data_type, struct inode *dir, 158 const struct qstr *file_name, u32 cookie, 159 struct fsnotify_iter_info *iter_info); 160 int (*handle_inode_event)(struct fsnotify_mark *mark, u32 mask, 161 struct inode *inode, struct inode *dir, 162 const struct qstr *file_name, u32 cookie); 163 void (*free_group_priv)(struct fsnotify_group *group); 164 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 165 void (*free_event)(struct fsnotify_group *group, struct fsnotify_event *event); 166 /* called on final put+free to free memory */ 167 void (*free_mark)(struct fsnotify_mark *mark); 168}; 169 170/* 171 * all of the information about the original object we want to now send to 172 * a group. If you want to carry more info from the accessing task to the 173 * listener this structure is where you need to be adding fields. 174 */ 175struct fsnotify_event { 176 struct list_head list; 177}; 178 179/* 180 * A group is a "thing" that wants to receive notification about filesystem 181 * events. The mask holds the subset of event types this group cares about. 182 * refcnt on a group is up to the implementor and at any moment if it goes 0 183 * everything will be cleaned up. 184 */ 185struct fsnotify_group { 186 const struct fsnotify_ops *ops; /* how this group handles things */ 187 188 /* 189 * How the refcnt is used is up to each group. When the refcnt hits 0 190 * fsnotify will clean up all of the resources associated with this group. 191 * As an example, the dnotify group will always have a refcnt=1 and that 192 * will never change. Inotify, on the other hand, has a group per 193 * inotify_init() and the refcnt will hit 0 only when that fd has been 194 * closed. 195 */ 196 refcount_t refcnt; /* things with interest in this group */ 197 198 /* needed to send notification to userspace */ 199 spinlock_t notification_lock; /* protect the notification_list */ 200 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ 201 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ 202 unsigned int q_len; /* events on the queue */ 203 unsigned int max_events; /* maximum events allowed on the list */ 204 /* 205 * Valid fsnotify group priorities. Events are send in order from highest 206 * priority to lowest priority. We default to the lowest priority. 207 */ 208 #define FS_PRIO_0 0 /* normal notifiers, no permissions */ 209 #define FS_PRIO_1 1 /* fanotify content based access control */ 210 #define FS_PRIO_2 2 /* fanotify pre-content access */ 211 unsigned int priority; 212 bool shutdown; /* group is being shut down, don't queue more events */ 213 214#define FSNOTIFY_GROUP_USER 0x01 /* user allocated group */ 215#define FSNOTIFY_GROUP_DUPS 0x02 /* allow multiple marks per object */ 216#define FSNOTIFY_GROUP_NOFS 0x04 /* group lock is not direct reclaim safe */ 217 int flags; 218 unsigned int owner_flags; /* stored flags of mark_mutex owner */ 219 220 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 221 struct mutex mark_mutex; /* protect marks_list */ 222 atomic_t user_waits; /* Number of tasks waiting for user 223 * response */ 224 struct list_head marks_list; /* all inode marks for this group */ 225 226 struct fasync_struct *fsn_fa; /* async notification */ 227 228 struct fsnotify_event *overflow_event; /* Event we queue when the 229 * notification list is too 230 * full */ 231 232 struct mem_cgroup *memcg; /* memcg to charge allocations */ 233 234 /* groups can define private fields here or use the void *private */ 235 union { 236 void *private; 237#ifdef CONFIG_INOTIFY_USER 238 struct inotify_group_private_data { 239 spinlock_t idr_lock; 240 struct idr idr; 241 struct ucounts *ucounts; 242 } inotify_data; 243#endif 244#ifdef CONFIG_FANOTIFY 245 struct fanotify_group_private_data { 246 /* Hash table of events for merge */ 247 struct hlist_head *merge_hash; 248 /* allows a group to block waiting for a userspace response */ 249 struct list_head access_list; 250 wait_queue_head_t access_waitq; 251 int flags; /* flags from fanotify_init() */ 252 int f_flags; /* event_f_flags from fanotify_init() */ 253 struct ucounts *ucounts; 254 mempool_t error_events_pool; 255 } fanotify_data; 256#endif /* CONFIG_FANOTIFY */ 257 }; 258}; 259 260/* 261 * These helpers are used to prevent deadlock when reclaiming inodes with 262 * evictable marks of the same group that is allocating a new mark. 263 */ 264static inline void fsnotify_group_lock(struct fsnotify_group *group) 265{ 266 mutex_lock(&group->mark_mutex); 267 if (group->flags & FSNOTIFY_GROUP_NOFS) 268 group->owner_flags = memalloc_nofs_save(); 269} 270 271static inline void fsnotify_group_unlock(struct fsnotify_group *group) 272{ 273 if (group->flags & FSNOTIFY_GROUP_NOFS) 274 memalloc_nofs_restore(group->owner_flags); 275 mutex_unlock(&group->mark_mutex); 276} 277 278static inline void fsnotify_group_assert_locked(struct fsnotify_group *group) 279{ 280 WARN_ON_ONCE(!mutex_is_locked(&group->mark_mutex)); 281 if (group->flags & FSNOTIFY_GROUP_NOFS) 282 WARN_ON_ONCE(!(current->flags & PF_MEMALLOC_NOFS)); 283} 284 285/* When calling fsnotify tell it if the data is a path or inode */ 286enum fsnotify_data_type { 287 FSNOTIFY_EVENT_NONE, 288 FSNOTIFY_EVENT_PATH, 289 FSNOTIFY_EVENT_INODE, 290 FSNOTIFY_EVENT_DENTRY, 291 FSNOTIFY_EVENT_ERROR, 292}; 293 294struct fs_error_report { 295 int error; 296 struct inode *inode; 297 struct super_block *sb; 298}; 299 300static inline struct inode *fsnotify_data_inode(const void *data, int data_type) 301{ 302 switch (data_type) { 303 case FSNOTIFY_EVENT_INODE: 304 return (struct inode *)data; 305 case FSNOTIFY_EVENT_DENTRY: 306 return d_inode(data); 307 case FSNOTIFY_EVENT_PATH: 308 return d_inode(((const struct path *)data)->dentry); 309 case FSNOTIFY_EVENT_ERROR: 310 return ((struct fs_error_report *)data)->inode; 311 default: 312 return NULL; 313 } 314} 315 316static inline struct dentry *fsnotify_data_dentry(const void *data, int data_type) 317{ 318 switch (data_type) { 319 case FSNOTIFY_EVENT_DENTRY: 320 /* Non const is needed for dget() */ 321 return (struct dentry *)data; 322 case FSNOTIFY_EVENT_PATH: 323 return ((const struct path *)data)->dentry; 324 default: 325 return NULL; 326 } 327} 328 329static inline const struct path *fsnotify_data_path(const void *data, 330 int data_type) 331{ 332 switch (data_type) { 333 case FSNOTIFY_EVENT_PATH: 334 return data; 335 default: 336 return NULL; 337 } 338} 339 340static inline struct super_block *fsnotify_data_sb(const void *data, 341 int data_type) 342{ 343 switch (data_type) { 344 case FSNOTIFY_EVENT_INODE: 345 return ((struct inode *)data)->i_sb; 346 case FSNOTIFY_EVENT_DENTRY: 347 return ((struct dentry *)data)->d_sb; 348 case FSNOTIFY_EVENT_PATH: 349 return ((const struct path *)data)->dentry->d_sb; 350 case FSNOTIFY_EVENT_ERROR: 351 return ((struct fs_error_report *) data)->sb; 352 default: 353 return NULL; 354 } 355} 356 357static inline struct fs_error_report *fsnotify_data_error_report( 358 const void *data, 359 int data_type) 360{ 361 switch (data_type) { 362 case FSNOTIFY_EVENT_ERROR: 363 return (struct fs_error_report *) data; 364 default: 365 return NULL; 366 } 367} 368 369/* 370 * Index to merged marks iterator array that correlates to a type of watch. 371 * The type of watched object can be deduced from the iterator type, but not 372 * the other way around, because an event can match different watched objects 373 * of the same object type. 374 * For example, both parent and child are watching an object of type inode. 375 */ 376enum fsnotify_iter_type { 377 FSNOTIFY_ITER_TYPE_INODE, 378 FSNOTIFY_ITER_TYPE_VFSMOUNT, 379 FSNOTIFY_ITER_TYPE_SB, 380 FSNOTIFY_ITER_TYPE_PARENT, 381 FSNOTIFY_ITER_TYPE_INODE2, 382 FSNOTIFY_ITER_TYPE_COUNT 383}; 384 385/* The type of object that a mark is attached to */ 386enum fsnotify_obj_type { 387 FSNOTIFY_OBJ_TYPE_ANY = -1, 388 FSNOTIFY_OBJ_TYPE_INODE, 389 FSNOTIFY_OBJ_TYPE_VFSMOUNT, 390 FSNOTIFY_OBJ_TYPE_SB, 391 FSNOTIFY_OBJ_TYPE_COUNT, 392 FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT 393}; 394 395static inline bool fsnotify_valid_obj_type(unsigned int obj_type) 396{ 397 return (obj_type < FSNOTIFY_OBJ_TYPE_COUNT); 398} 399 400struct fsnotify_iter_info { 401 struct fsnotify_mark *marks[FSNOTIFY_ITER_TYPE_COUNT]; 402 struct fsnotify_group *current_group; 403 unsigned int report_mask; 404 int srcu_idx; 405}; 406 407static inline bool fsnotify_iter_should_report_type( 408 struct fsnotify_iter_info *iter_info, int iter_type) 409{ 410 return (iter_info->report_mask & (1U << iter_type)); 411} 412 413static inline void fsnotify_iter_set_report_type( 414 struct fsnotify_iter_info *iter_info, int iter_type) 415{ 416 iter_info->report_mask |= (1U << iter_type); 417} 418 419static inline struct fsnotify_mark *fsnotify_iter_mark( 420 struct fsnotify_iter_info *iter_info, int iter_type) 421{ 422 if (fsnotify_iter_should_report_type(iter_info, iter_type)) 423 return iter_info->marks[iter_type]; 424 return NULL; 425} 426 427static inline int fsnotify_iter_step(struct fsnotify_iter_info *iter, int type, 428 struct fsnotify_mark **markp) 429{ 430 while (type < FSNOTIFY_ITER_TYPE_COUNT) { 431 *markp = fsnotify_iter_mark(iter, type); 432 if (*markp) 433 break; 434 type++; 435 } 436 return type; 437} 438 439#define FSNOTIFY_ITER_FUNCS(name, NAME) \ 440static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \ 441 struct fsnotify_iter_info *iter_info) \ 442{ \ 443 return fsnotify_iter_mark(iter_info, FSNOTIFY_ITER_TYPE_##NAME); \ 444} 445 446FSNOTIFY_ITER_FUNCS(inode, INODE) 447FSNOTIFY_ITER_FUNCS(parent, PARENT) 448FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT) 449FSNOTIFY_ITER_FUNCS(sb, SB) 450 451#define fsnotify_foreach_iter_type(type) \ 452 for (type = 0; type < FSNOTIFY_ITER_TYPE_COUNT; type++) 453#define fsnotify_foreach_iter_mark_type(iter, mark, type) \ 454 for (type = 0; \ 455 type = fsnotify_iter_step(iter, type, &mark), \ 456 type < FSNOTIFY_ITER_TYPE_COUNT; \ 457 type++) 458 459/* 460 * fsnotify_connp_t is what we embed in objects which connector can be attached 461 * to. fsnotify_connp_t * is how we refer from connector back to object. 462 */ 463struct fsnotify_mark_connector; 464typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t; 465 466/* 467 * Inode/vfsmount/sb point to this structure which tracks all marks attached to 468 * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this 469 * structure. We destroy this structure when there are no more marks attached 470 * to it. The structure is protected by fsnotify_mark_srcu. 471 */ 472struct fsnotify_mark_connector { 473 spinlock_t lock; 474 unsigned short type; /* Type of object [lock] */ 475#define FSNOTIFY_CONN_FLAG_HAS_IREF 0x02 476 unsigned short flags; /* flags [lock] */ 477 union { 478 /* Object pointer [lock] */ 479 fsnotify_connp_t *obj; 480 /* Used listing heads to free after srcu period expires */ 481 struct fsnotify_mark_connector *destroy_next; 482 }; 483 struct hlist_head list; 484}; 485 486/* 487 * A mark is simply an object attached to an in core inode which allows an 488 * fsnotify listener to indicate they are either no longer interested in events 489 * of a type matching mask or only interested in those events. 490 * 491 * These are flushed when an inode is evicted from core and may be flushed 492 * when the inode is modified (as seen by fsnotify_access). Some fsnotify 493 * users (such as dnotify) will flush these when the open fd is closed and not 494 * at inode eviction or modification. 495 * 496 * Text in brackets is showing the lock(s) protecting modifications of a 497 * particular entry. obj_lock means either inode->i_lock or 498 * mnt->mnt_root->d_lock depending on the mark type. 499 */ 500struct fsnotify_mark { 501 /* Mask this mark is for [mark->lock, group->mark_mutex] */ 502 __u32 mask; 503 /* We hold one for presence in g_list. Also one ref for each 'thing' 504 * in kernel that found and may be using this mark. */ 505 refcount_t refcnt; 506 /* Group this mark is for. Set on mark creation, stable until last ref 507 * is dropped */ 508 struct fsnotify_group *group; 509 /* List of marks by group->marks_list. Also reused for queueing 510 * mark into destroy_list when it's waiting for the end of SRCU period 511 * before it can be freed. [group->mark_mutex] */ 512 struct list_head g_list; 513 /* Protects inode / mnt pointers, flags, masks */ 514 spinlock_t lock; 515 /* List of marks for inode / vfsmount [connector->lock, mark ref] */ 516 struct hlist_node obj_list; 517 /* Head of list of marks for an object [mark ref] */ 518 struct fsnotify_mark_connector *connector; 519 /* Events types and flags to ignore [mark->lock, group->mark_mutex] */ 520 __u32 ignore_mask; 521 /* General fsnotify mark flags */ 522#define FSNOTIFY_MARK_FLAG_ALIVE 0x0001 523#define FSNOTIFY_MARK_FLAG_ATTACHED 0x0002 524 /* inotify mark flags */ 525#define FSNOTIFY_MARK_FLAG_EXCL_UNLINK 0x0010 526#define FSNOTIFY_MARK_FLAG_IN_ONESHOT 0x0020 527 /* fanotify mark flags */ 528#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x0100 529#define FSNOTIFY_MARK_FLAG_NO_IREF 0x0200 530#define FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS 0x0400 531#define FSNOTIFY_MARK_FLAG_HAS_FSID 0x0800 532#define FSNOTIFY_MARK_FLAG_WEAK_FSID 0x1000 533 unsigned int flags; /* flags [mark->lock] */ 534}; 535 536#ifdef CONFIG_FSNOTIFY 537 538/* called from the vfs helpers */ 539 540/* main fsnotify call to send events */ 541extern int fsnotify(__u32 mask, const void *data, int data_type, 542 struct inode *dir, const struct qstr *name, 543 struct inode *inode, u32 cookie); 544extern int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data, 545 int data_type); 546extern void __fsnotify_inode_delete(struct inode *inode); 547extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 548extern void fsnotify_sb_delete(struct super_block *sb); 549extern u32 fsnotify_get_cookie(void); 550 551static inline __u32 fsnotify_parent_needed_mask(__u32 mask) 552{ 553 /* FS_EVENT_ON_CHILD is set on marks that want parent/name info */ 554 if (!(mask & FS_EVENT_ON_CHILD)) 555 return 0; 556 /* 557 * This object might be watched by a mark that cares about parent/name 558 * info, does it care about the specific set of events that can be 559 * reported with parent/name info? 560 */ 561 return mask & FS_EVENTS_POSS_TO_PARENT; 562} 563 564static inline int fsnotify_inode_watches_children(struct inode *inode) 565{ 566 /* FS_EVENT_ON_CHILD is set if the inode may care */ 567 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 568 return 0; 569 /* this inode might care about child events, does it care about the 570 * specific set of events that can happen on a child? */ 571 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 572} 573 574/* 575 * Update the dentry with a flag indicating the interest of its parent to receive 576 * filesystem events when those events happens to this dentry->d_inode. 577 */ 578static inline void fsnotify_update_flags(struct dentry *dentry) 579{ 580 assert_spin_locked(&dentry->d_lock); 581 582 /* 583 * Serialisation of setting PARENT_WATCHED on the dentries is provided 584 * by d_lock. If inotify_inode_watched changes after we have taken 585 * d_lock, the following __fsnotify_update_child_dentry_flags call will 586 * find our entry, so it will spin until we complete here, and update 587 * us with the new state. 588 */ 589 if (fsnotify_inode_watches_children(dentry->d_parent->d_inode)) 590 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 591 else 592 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 593} 594 595/* called from fsnotify listeners, such as fanotify or dnotify */ 596 597/* create a new group */ 598extern struct fsnotify_group *fsnotify_alloc_group( 599 const struct fsnotify_ops *ops, 600 int flags); 601/* get reference to a group */ 602extern void fsnotify_get_group(struct fsnotify_group *group); 603/* drop reference on a group from fsnotify_alloc_group */ 604extern void fsnotify_put_group(struct fsnotify_group *group); 605/* group destruction begins, stop queuing new events */ 606extern void fsnotify_group_stop_queueing(struct fsnotify_group *group); 607/* destroy group */ 608extern void fsnotify_destroy_group(struct fsnotify_group *group); 609/* fasync handler function */ 610extern int fsnotify_fasync(int fd, struct file *file, int on); 611/* Free event from memory */ 612extern void fsnotify_destroy_event(struct fsnotify_group *group, 613 struct fsnotify_event *event); 614/* attach the event to the group notification queue */ 615extern int fsnotify_insert_event(struct fsnotify_group *group, 616 struct fsnotify_event *event, 617 int (*merge)(struct fsnotify_group *, 618 struct fsnotify_event *), 619 void (*insert)(struct fsnotify_group *, 620 struct fsnotify_event *)); 621 622static inline int fsnotify_add_event(struct fsnotify_group *group, 623 struct fsnotify_event *event, 624 int (*merge)(struct fsnotify_group *, 625 struct fsnotify_event *)) 626{ 627 return fsnotify_insert_event(group, event, merge, NULL); 628} 629 630/* Queue overflow event to a notification group */ 631static inline void fsnotify_queue_overflow(struct fsnotify_group *group) 632{ 633 fsnotify_add_event(group, group->overflow_event, NULL); 634} 635 636static inline bool fsnotify_is_overflow_event(u32 mask) 637{ 638 return mask & FS_Q_OVERFLOW; 639} 640 641static inline bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group) 642{ 643 assert_spin_locked(&group->notification_lock); 644 645 return list_empty(&group->notification_list); 646} 647 648extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 649/* return, but do not dequeue the first event on the notification queue */ 650extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group); 651/* return AND dequeue the first event on the notification queue */ 652extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group); 653/* Remove event queued in the notification list */ 654extern void fsnotify_remove_queued_event(struct fsnotify_group *group, 655 struct fsnotify_event *event); 656 657/* functions used to manipulate the marks attached to inodes */ 658 659/* 660 * Canonical "ignore mask" including event flags. 661 * 662 * Note the subtle semantic difference from the legacy ->ignored_mask. 663 * ->ignored_mask traditionally only meant which events should be ignored, 664 * while ->ignore_mask also includes flags regarding the type of objects on 665 * which events should be ignored. 666 */ 667static inline __u32 fsnotify_ignore_mask(struct fsnotify_mark *mark) 668{ 669 __u32 ignore_mask = mark->ignore_mask; 670 671 /* The event flags in ignore mask take effect */ 672 if (mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS) 673 return ignore_mask; 674 675 /* 676 * Legacy behavior: 677 * - Always ignore events on dir 678 * - Ignore events on child if parent is watching children 679 */ 680 ignore_mask |= FS_ISDIR; 681 ignore_mask &= ~FS_EVENT_ON_CHILD; 682 ignore_mask |= mark->mask & FS_EVENT_ON_CHILD; 683 684 return ignore_mask; 685} 686 687/* Legacy ignored_mask - only event types to ignore */ 688static inline __u32 fsnotify_ignored_events(struct fsnotify_mark *mark) 689{ 690 return mark->ignore_mask & ALL_FSNOTIFY_EVENTS; 691} 692 693/* 694 * Check if mask (or ignore mask) should be applied depending if victim is a 695 * directory and whether it is reported to a watching parent. 696 */ 697static inline bool fsnotify_mask_applicable(__u32 mask, bool is_dir, 698 int iter_type) 699{ 700 /* Should mask be applied to a directory? */ 701 if (is_dir && !(mask & FS_ISDIR)) 702 return false; 703 704 /* Should mask be applied to a child? */ 705 if (iter_type == FSNOTIFY_ITER_TYPE_PARENT && 706 !(mask & FS_EVENT_ON_CHILD)) 707 return false; 708 709 return true; 710} 711 712/* 713 * Effective ignore mask taking into account if event victim is a 714 * directory and whether it is reported to a watching parent. 715 */ 716static inline __u32 fsnotify_effective_ignore_mask(struct fsnotify_mark *mark, 717 bool is_dir, int iter_type) 718{ 719 __u32 ignore_mask = fsnotify_ignored_events(mark); 720 721 if (!ignore_mask) 722 return 0; 723 724 /* For non-dir and non-child, no need to consult the event flags */ 725 if (!is_dir && iter_type != FSNOTIFY_ITER_TYPE_PARENT) 726 return ignore_mask; 727 728 ignore_mask = fsnotify_ignore_mask(mark); 729 if (!fsnotify_mask_applicable(ignore_mask, is_dir, iter_type)) 730 return 0; 731 732 return ignore_mask & ALL_FSNOTIFY_EVENTS; 733} 734 735/* Get mask for calculating object interest taking ignore mask into account */ 736static inline __u32 fsnotify_calc_mask(struct fsnotify_mark *mark) 737{ 738 __u32 mask = mark->mask; 739 740 if (!fsnotify_ignored_events(mark)) 741 return mask; 742 743 /* Interest in FS_MODIFY may be needed for clearing ignore mask */ 744 if (!(mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 745 mask |= FS_MODIFY; 746 747 /* 748 * If mark is interested in ignoring events on children, the object must 749 * show interest in those events for fsnotify_parent() to notice it. 750 */ 751 return mask | mark->ignore_mask; 752} 753 754/* Get mask of events for a list of marks */ 755extern __u32 fsnotify_conn_mask(struct fsnotify_mark_connector *conn); 756/* Calculate mask of events for a list of marks */ 757extern void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn); 758extern void fsnotify_init_mark(struct fsnotify_mark *mark, 759 struct fsnotify_group *group); 760/* Find mark belonging to given group in the list of marks */ 761extern struct fsnotify_mark *fsnotify_find_mark(fsnotify_connp_t *connp, 762 struct fsnotify_group *group); 763/* attach the mark to the object */ 764extern int fsnotify_add_mark(struct fsnotify_mark *mark, 765 fsnotify_connp_t *connp, unsigned int obj_type, 766 int add_flags); 767extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, 768 fsnotify_connp_t *connp, 769 unsigned int obj_type, int add_flags); 770 771/* attach the mark to the inode */ 772static inline int fsnotify_add_inode_mark(struct fsnotify_mark *mark, 773 struct inode *inode, 774 int add_flags) 775{ 776 return fsnotify_add_mark(mark, &inode->i_fsnotify_marks, 777 FSNOTIFY_OBJ_TYPE_INODE, add_flags); 778} 779static inline int fsnotify_add_inode_mark_locked(struct fsnotify_mark *mark, 780 struct inode *inode, 781 int add_flags) 782{ 783 return fsnotify_add_mark_locked(mark, &inode->i_fsnotify_marks, 784 FSNOTIFY_OBJ_TYPE_INODE, add_flags); 785} 786 787/* given a group and a mark, flag mark to be freed when all references are dropped */ 788extern void fsnotify_destroy_mark(struct fsnotify_mark *mark, 789 struct fsnotify_group *group); 790/* detach mark from inode / mount list, group list, drop inode reference */ 791extern void fsnotify_detach_mark(struct fsnotify_mark *mark); 792/* free mark */ 793extern void fsnotify_free_mark(struct fsnotify_mark *mark); 794/* Wait until all marks queued for destruction are destroyed */ 795extern void fsnotify_wait_marks_destroyed(void); 796/* Clear all of the marks of a group attached to a given object type */ 797extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group, 798 unsigned int obj_type); 799/* run all the marks in a group, and clear all of the vfsmount marks */ 800static inline void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group) 801{ 802 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT); 803} 804/* run all the marks in a group, and clear all of the inode marks */ 805static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group) 806{ 807 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE); 808} 809/* run all the marks in a group, and clear all of the sn marks */ 810static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group) 811{ 812 fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_SB); 813} 814extern void fsnotify_get_mark(struct fsnotify_mark *mark); 815extern void fsnotify_put_mark(struct fsnotify_mark *mark); 816extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info); 817extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info); 818 819static inline void fsnotify_init_event(struct fsnotify_event *event) 820{ 821 INIT_LIST_HEAD(&event->list); 822} 823 824#else 825 826static inline int fsnotify(__u32 mask, const void *data, int data_type, 827 struct inode *dir, const struct qstr *name, 828 struct inode *inode, u32 cookie) 829{ 830 return 0; 831} 832 833static inline int __fsnotify_parent(struct dentry *dentry, __u32 mask, 834 const void *data, int data_type) 835{ 836 return 0; 837} 838 839static inline void __fsnotify_inode_delete(struct inode *inode) 840{} 841 842static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 843{} 844 845static inline void fsnotify_sb_delete(struct super_block *sb) 846{} 847 848static inline void fsnotify_update_flags(struct dentry *dentry) 849{} 850 851static inline u32 fsnotify_get_cookie(void) 852{ 853 return 0; 854} 855 856static inline void fsnotify_unmount_inodes(struct super_block *sb) 857{} 858 859#endif /* CONFIG_FSNOTIFY */ 860 861#endif /* __KERNEL __ */ 862 863#endif /* __LINUX_FSNOTIFY_BACKEND_H */ 864