1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * fs/inotify_user.c - inotify support for userspace 4 * 5 * Authors: 6 * John McCutchan <ttb@tentacle.dhs.org> 7 * Robert Love <rml@novell.com> 8 * 9 * Copyright (C) 2005 John McCutchan 10 * Copyright 2006 Hewlett-Packard Development Company, L.P. 11 * 12 * Copyright (C) 2009 Eric Paris <Red Hat Inc> 13 * inotify was largely rewriten to make use of the fsnotify infrastructure 14 */ 15 16#include <linux/file.h> 17#include <linux/fs.h> /* struct inode */ 18#include <linux/fsnotify_backend.h> 19#include <linux/idr.h> 20#include <linux/init.h> /* fs_initcall */ 21#include <linux/inotify.h> 22#include <linux/kernel.h> /* roundup() */ 23#include <linux/namei.h> /* LOOKUP_FOLLOW */ 24#include <linux/sched/signal.h> 25#include <linux/slab.h> /* struct kmem_cache */ 26#include <linux/syscalls.h> 27#include <linux/types.h> 28#include <linux/anon_inodes.h> 29#include <linux/uaccess.h> 30#include <linux/poll.h> 31#include <linux/wait.h> 32#include <linux/memcontrol.h> 33#include <linux/security.h> 34 35#include "inotify.h" 36#include "../fdinfo.h" 37 38#include <asm/ioctls.h> 39 40/* 41 * An inotify watch requires allocating an inotify_inode_mark structure as 42 * well as pinning the watched inode. Doubling the size of a VFS inode 43 * should be more than enough to cover the additional filesystem inode 44 * size increase. 45 */ 46#define INOTIFY_WATCH_COST (sizeof(struct inotify_inode_mark) + \ 47 2 * sizeof(struct inode)) 48 49/* configurable via /proc/sys/fs/inotify/ */ 50static int inotify_max_queued_events __read_mostly; 51 52struct kmem_cache *inotify_inode_mark_cachep __ro_after_init; 53 54#ifdef CONFIG_SYSCTL 55 56#include <linux/sysctl.h> 57 58static long it_zero = 0; 59static long it_int_max = INT_MAX; 60 61static struct ctl_table inotify_table[] = { 62 { 63 .procname = "max_user_instances", 64 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES], 65 .maxlen = sizeof(long), 66 .mode = 0644, 67 .proc_handler = proc_doulongvec_minmax, 68 .extra1 = &it_zero, 69 .extra2 = &it_int_max, 70 }, 71 { 72 .procname = "max_user_watches", 73 .data = &init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES], 74 .maxlen = sizeof(long), 75 .mode = 0644, 76 .proc_handler = proc_doulongvec_minmax, 77 .extra1 = &it_zero, 78 .extra2 = &it_int_max, 79 }, 80 { 81 .procname = "max_queued_events", 82 .data = &inotify_max_queued_events, 83 .maxlen = sizeof(int), 84 .mode = 0644, 85 .proc_handler = proc_dointvec_minmax, 86 .extra1 = SYSCTL_ZERO 87 }, 88}; 89 90static void __init inotify_sysctls_init(void) 91{ 92 register_sysctl("fs/inotify", inotify_table); 93} 94 95#else 96#define inotify_sysctls_init() do { } while (0) 97#endif /* CONFIG_SYSCTL */ 98 99static inline __u32 inotify_arg_to_mask(struct inode *inode, u32 arg) 100{ 101 __u32 mask; 102 103 /* 104 * Everything should receive events when the inode is unmounted. 105 * All directories care about children. 106 */ 107 mask = (FS_UNMOUNT); 108 if (S_ISDIR(inode->i_mode)) 109 mask |= FS_EVENT_ON_CHILD; 110 111 /* mask off the flags used to open the fd */ 112 mask |= (arg & INOTIFY_USER_MASK); 113 114 return mask; 115} 116 117#define INOTIFY_MARK_FLAGS \ 118 (FSNOTIFY_MARK_FLAG_EXCL_UNLINK | FSNOTIFY_MARK_FLAG_IN_ONESHOT) 119 120static inline unsigned int inotify_arg_to_flags(u32 arg) 121{ 122 unsigned int flags = 0; 123 124 if (arg & IN_EXCL_UNLINK) 125 flags |= FSNOTIFY_MARK_FLAG_EXCL_UNLINK; 126 if (arg & IN_ONESHOT) 127 flags |= FSNOTIFY_MARK_FLAG_IN_ONESHOT; 128 129 return flags; 130} 131 132static inline u32 inotify_mask_to_arg(__u32 mask) 133{ 134 return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | 135 IN_Q_OVERFLOW); 136} 137 138/* inotify userspace file descriptor functions */ 139static __poll_t inotify_poll(struct file *file, poll_table *wait) 140{ 141 struct fsnotify_group *group = file->private_data; 142 __poll_t ret = 0; 143 144 poll_wait(file, &group->notification_waitq, wait); 145 spin_lock(&group->notification_lock); 146 if (!fsnotify_notify_queue_is_empty(group)) 147 ret = EPOLLIN | EPOLLRDNORM; 148 spin_unlock(&group->notification_lock); 149 150 return ret; 151} 152 153static int round_event_name_len(struct fsnotify_event *fsn_event) 154{ 155 struct inotify_event_info *event; 156 157 event = INOTIFY_E(fsn_event); 158 if (!event->name_len) 159 return 0; 160 return roundup(event->name_len + 1, sizeof(struct inotify_event)); 161} 162 163/* 164 * Get an inotify_kernel_event if one exists and is small 165 * enough to fit in "count". Return an error pointer if 166 * not large enough. 167 * 168 * Called with the group->notification_lock held. 169 */ 170static struct fsnotify_event *get_one_event(struct fsnotify_group *group, 171 size_t count) 172{ 173 size_t event_size = sizeof(struct inotify_event); 174 struct fsnotify_event *event; 175 176 event = fsnotify_peek_first_event(group); 177 if (!event) 178 return NULL; 179 180 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 181 182 event_size += round_event_name_len(event); 183 if (event_size > count) 184 return ERR_PTR(-EINVAL); 185 186 /* held the notification_lock the whole time, so this is the 187 * same event we peeked above */ 188 fsnotify_remove_first_event(group); 189 190 return event; 191} 192 193/* 194 * Copy an event to user space, returning how much we copied. 195 * 196 * We already checked that the event size is smaller than the 197 * buffer we had in "get_one_event()" above. 198 */ 199static ssize_t copy_event_to_user(struct fsnotify_group *group, 200 struct fsnotify_event *fsn_event, 201 char __user *buf) 202{ 203 struct inotify_event inotify_event; 204 struct inotify_event_info *event; 205 size_t event_size = sizeof(struct inotify_event); 206 size_t name_len; 207 size_t pad_name_len; 208 209 pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event); 210 211 event = INOTIFY_E(fsn_event); 212 name_len = event->name_len; 213 /* 214 * round up name length so it is a multiple of event_size 215 * plus an extra byte for the terminating '\0'. 216 */ 217 pad_name_len = round_event_name_len(fsn_event); 218 inotify_event.len = pad_name_len; 219 inotify_event.mask = inotify_mask_to_arg(event->mask); 220 inotify_event.wd = event->wd; 221 inotify_event.cookie = event->sync_cookie; 222 223 /* send the main event */ 224 if (copy_to_user(buf, &inotify_event, event_size)) 225 return -EFAULT; 226 227 buf += event_size; 228 229 /* 230 * fsnotify only stores the pathname, so here we have to send the pathname 231 * and then pad that pathname out to a multiple of sizeof(inotify_event) 232 * with zeros. 233 */ 234 if (pad_name_len) { 235 /* copy the path name */ 236 if (copy_to_user(buf, event->name, name_len)) 237 return -EFAULT; 238 buf += name_len; 239 240 /* fill userspace with 0's */ 241 if (clear_user(buf, pad_name_len - name_len)) 242 return -EFAULT; 243 event_size += pad_name_len; 244 } 245 246 return event_size; 247} 248 249static ssize_t inotify_read(struct file *file, char __user *buf, 250 size_t count, loff_t *pos) 251{ 252 struct fsnotify_group *group; 253 struct fsnotify_event *kevent; 254 char __user *start; 255 int ret; 256 DEFINE_WAIT_FUNC(wait, woken_wake_function); 257 258 start = buf; 259 group = file->private_data; 260 261 add_wait_queue(&group->notification_waitq, &wait); 262 while (1) { 263 spin_lock(&group->notification_lock); 264 kevent = get_one_event(group, count); 265 spin_unlock(&group->notification_lock); 266 267 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); 268 269 if (kevent) { 270 ret = PTR_ERR(kevent); 271 if (IS_ERR(kevent)) 272 break; 273 ret = copy_event_to_user(group, kevent, buf); 274 fsnotify_destroy_event(group, kevent); 275 if (ret < 0) 276 break; 277 buf += ret; 278 count -= ret; 279 continue; 280 } 281 282 ret = -EAGAIN; 283 if (file->f_flags & O_NONBLOCK) 284 break; 285 ret = -ERESTARTSYS; 286 if (signal_pending(current)) 287 break; 288 289 if (start != buf) 290 break; 291 292 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 293 } 294 remove_wait_queue(&group->notification_waitq, &wait); 295 296 if (start != buf && ret != -EFAULT) 297 ret = buf - start; 298 return ret; 299} 300 301static int inotify_release(struct inode *ignored, struct file *file) 302{ 303 struct fsnotify_group *group = file->private_data; 304 305 pr_debug("%s: group=%p\n", __func__, group); 306 307 /* free this group, matching get was inotify_init->fsnotify_obtain_group */ 308 fsnotify_destroy_group(group); 309 310 return 0; 311} 312 313static long inotify_ioctl(struct file *file, unsigned int cmd, 314 unsigned long arg) 315{ 316 struct fsnotify_group *group; 317 struct fsnotify_event *fsn_event; 318 void __user *p; 319 int ret = -ENOTTY; 320 size_t send_len = 0; 321 322 group = file->private_data; 323 p = (void __user *) arg; 324 325 pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd); 326 327 switch (cmd) { 328 case FIONREAD: 329 spin_lock(&group->notification_lock); 330 list_for_each_entry(fsn_event, &group->notification_list, 331 list) { 332 send_len += sizeof(struct inotify_event); 333 send_len += round_event_name_len(fsn_event); 334 } 335 spin_unlock(&group->notification_lock); 336 ret = put_user(send_len, (int __user *) p); 337 break; 338#ifdef CONFIG_CHECKPOINT_RESTORE 339 case INOTIFY_IOC_SETNEXTWD: 340 ret = -EINVAL; 341 if (arg >= 1 && arg <= INT_MAX) { 342 struct inotify_group_private_data *data; 343 344 data = &group->inotify_data; 345 spin_lock(&data->idr_lock); 346 idr_set_cursor(&data->idr, (unsigned int)arg); 347 spin_unlock(&data->idr_lock); 348 ret = 0; 349 } 350 break; 351#endif /* CONFIG_CHECKPOINT_RESTORE */ 352 } 353 354 return ret; 355} 356 357static const struct file_operations inotify_fops = { 358 .show_fdinfo = inotify_show_fdinfo, 359 .poll = inotify_poll, 360 .read = inotify_read, 361 .fasync = fsnotify_fasync, 362 .release = inotify_release, 363 .unlocked_ioctl = inotify_ioctl, 364 .compat_ioctl = inotify_ioctl, 365 .llseek = noop_llseek, 366}; 367 368 369/* 370 * find_inode - resolve a user-given path to a specific inode 371 */ 372static int inotify_find_inode(const char __user *dirname, struct path *path, 373 unsigned int flags, __u64 mask) 374{ 375 int error; 376 377 error = user_path_at(AT_FDCWD, dirname, flags, path); 378 if (error) 379 return error; 380 /* you can only watch an inode if you have read permissions on it */ 381 error = path_permission(path, MAY_READ); 382 if (error) { 383 path_put(path); 384 return error; 385 } 386 error = security_path_notify(path, mask, 387 FSNOTIFY_OBJ_TYPE_INODE); 388 if (error) 389 path_put(path); 390 391 return error; 392} 393 394static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock, 395 struct inotify_inode_mark *i_mark) 396{ 397 int ret; 398 399 idr_preload(GFP_KERNEL); 400 spin_lock(idr_lock); 401 402 ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT); 403 if (ret >= 0) { 404 /* we added the mark to the idr, take a reference */ 405 i_mark->wd = ret; 406 fsnotify_get_mark(&i_mark->fsn_mark); 407 } 408 409 spin_unlock(idr_lock); 410 idr_preload_end(); 411 return ret < 0 ? ret : 0; 412} 413 414static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group, 415 int wd) 416{ 417 struct idr *idr = &group->inotify_data.idr; 418 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 419 struct inotify_inode_mark *i_mark; 420 421 assert_spin_locked(idr_lock); 422 423 i_mark = idr_find(idr, wd); 424 if (i_mark) { 425 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark; 426 427 fsnotify_get_mark(fsn_mark); 428 /* One ref for being in the idr, one ref we just took */ 429 BUG_ON(refcount_read(&fsn_mark->refcnt) < 2); 430 } 431 432 return i_mark; 433} 434 435static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group, 436 int wd) 437{ 438 struct inotify_inode_mark *i_mark; 439 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 440 441 spin_lock(idr_lock); 442 i_mark = inotify_idr_find_locked(group, wd); 443 spin_unlock(idr_lock); 444 445 return i_mark; 446} 447 448/* 449 * Remove the mark from the idr (if present) and drop the reference 450 * on the mark because it was in the idr. 451 */ 452static void inotify_remove_from_idr(struct fsnotify_group *group, 453 struct inotify_inode_mark *i_mark) 454{ 455 struct idr *idr = &group->inotify_data.idr; 456 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 457 struct inotify_inode_mark *found_i_mark = NULL; 458 int wd; 459 460 spin_lock(idr_lock); 461 wd = i_mark->wd; 462 463 /* 464 * does this i_mark think it is in the idr? we shouldn't get called 465 * if it wasn't.... 466 */ 467 if (wd == -1) { 468 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", 469 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); 470 goto out; 471 } 472 473 /* Lets look in the idr to see if we find it */ 474 found_i_mark = inotify_idr_find_locked(group, wd); 475 if (unlikely(!found_i_mark)) { 476 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", 477 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); 478 goto out; 479 } 480 481 /* 482 * We found an mark in the idr at the right wd, but it's 483 * not the mark we were told to remove. eparis seriously 484 * fucked up somewhere. 485 */ 486 if (unlikely(found_i_mark != i_mark)) { 487 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p " 488 "found_i_mark=%p found_i_mark->wd=%d " 489 "found_i_mark->group=%p\n", __func__, i_mark, 490 i_mark->wd, i_mark->fsn_mark.group, found_i_mark, 491 found_i_mark->wd, found_i_mark->fsn_mark.group); 492 goto out; 493 } 494 495 /* 496 * One ref for being in the idr 497 * one ref grabbed by inotify_idr_find 498 */ 499 if (unlikely(refcount_read(&i_mark->fsn_mark.refcnt) < 2)) { 500 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p\n", 501 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group); 502 /* we can't really recover with bad ref cnting.. */ 503 BUG(); 504 } 505 506 idr_remove(idr, wd); 507 /* Removed from the idr, drop that ref. */ 508 fsnotify_put_mark(&i_mark->fsn_mark); 509out: 510 i_mark->wd = -1; 511 spin_unlock(idr_lock); 512 /* match the ref taken by inotify_idr_find_locked() */ 513 if (found_i_mark) 514 fsnotify_put_mark(&found_i_mark->fsn_mark); 515} 516 517/* 518 * Send IN_IGNORED for this wd, remove this wd from the idr. 519 */ 520void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, 521 struct fsnotify_group *group) 522{ 523 struct inotify_inode_mark *i_mark; 524 525 /* Queue ignore event for the watch */ 526 inotify_handle_inode_event(fsn_mark, FS_IN_IGNORED, NULL, NULL, NULL, 527 0); 528 529 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 530 /* remove this mark from the idr */ 531 inotify_remove_from_idr(group, i_mark); 532 533 dec_inotify_watches(group->inotify_data.ucounts); 534} 535 536static int inotify_update_existing_watch(struct fsnotify_group *group, 537 struct inode *inode, 538 u32 arg) 539{ 540 struct fsnotify_mark *fsn_mark; 541 struct inotify_inode_mark *i_mark; 542 __u32 old_mask, new_mask; 543 int replace = !(arg & IN_MASK_ADD); 544 int create = (arg & IN_MASK_CREATE); 545 int ret; 546 547 fsn_mark = fsnotify_find_mark(&inode->i_fsnotify_marks, group); 548 if (!fsn_mark) 549 return -ENOENT; 550 else if (create) { 551 ret = -EEXIST; 552 goto out; 553 } 554 555 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 556 557 spin_lock(&fsn_mark->lock); 558 old_mask = fsn_mark->mask; 559 if (replace) { 560 fsn_mark->mask = 0; 561 fsn_mark->flags &= ~INOTIFY_MARK_FLAGS; 562 } 563 fsn_mark->mask |= inotify_arg_to_mask(inode, arg); 564 fsn_mark->flags |= inotify_arg_to_flags(arg); 565 new_mask = fsn_mark->mask; 566 spin_unlock(&fsn_mark->lock); 567 568 if (old_mask != new_mask) { 569 /* more bits in old than in new? */ 570 int dropped = (old_mask & ~new_mask); 571 /* more bits in this fsn_mark than the inode's mask? */ 572 int do_inode = (new_mask & ~inode->i_fsnotify_mask); 573 574 /* update the inode with this new fsn_mark */ 575 if (dropped || do_inode) 576 fsnotify_recalc_mask(inode->i_fsnotify_marks); 577 578 } 579 580 /* return the wd */ 581 ret = i_mark->wd; 582 583out: 584 /* match the get from fsnotify_find_mark() */ 585 fsnotify_put_mark(fsn_mark); 586 587 return ret; 588} 589 590static int inotify_new_watch(struct fsnotify_group *group, 591 struct inode *inode, 592 u32 arg) 593{ 594 struct inotify_inode_mark *tmp_i_mark; 595 int ret; 596 struct idr *idr = &group->inotify_data.idr; 597 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 598 599 tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); 600 if (unlikely(!tmp_i_mark)) 601 return -ENOMEM; 602 603 fsnotify_init_mark(&tmp_i_mark->fsn_mark, group); 604 tmp_i_mark->fsn_mark.mask = inotify_arg_to_mask(inode, arg); 605 tmp_i_mark->fsn_mark.flags = inotify_arg_to_flags(arg); 606 tmp_i_mark->wd = -1; 607 608 ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark); 609 if (ret) 610 goto out_err; 611 612 /* increment the number of watches the user has */ 613 if (!inc_inotify_watches(group->inotify_data.ucounts)) { 614 inotify_remove_from_idr(group, tmp_i_mark); 615 ret = -ENOSPC; 616 goto out_err; 617 } 618 619 /* we are on the idr, now get on the inode */ 620 ret = fsnotify_add_inode_mark_locked(&tmp_i_mark->fsn_mark, inode, 0); 621 if (ret) { 622 /* we failed to get on the inode, get off the idr */ 623 inotify_remove_from_idr(group, tmp_i_mark); 624 goto out_err; 625 } 626 627 628 /* return the watch descriptor for this new mark */ 629 ret = tmp_i_mark->wd; 630 631out_err: 632 /* match the ref from fsnotify_init_mark() */ 633 fsnotify_put_mark(&tmp_i_mark->fsn_mark); 634 635 return ret; 636} 637 638static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) 639{ 640 int ret = 0; 641 642 fsnotify_group_lock(group); 643 /* try to update and existing watch with the new arg */ 644 ret = inotify_update_existing_watch(group, inode, arg); 645 /* no mark present, try to add a new one */ 646 if (ret == -ENOENT) 647 ret = inotify_new_watch(group, inode, arg); 648 fsnotify_group_unlock(group); 649 650 return ret; 651} 652 653static struct fsnotify_group *inotify_new_group(unsigned int max_events) 654{ 655 struct fsnotify_group *group; 656 struct inotify_event_info *oevent; 657 658 group = fsnotify_alloc_group(&inotify_fsnotify_ops, 659 FSNOTIFY_GROUP_USER); 660 if (IS_ERR(group)) 661 return group; 662 663 oevent = kmalloc(sizeof(struct inotify_event_info), GFP_KERNEL_ACCOUNT); 664 if (unlikely(!oevent)) { 665 fsnotify_destroy_group(group); 666 return ERR_PTR(-ENOMEM); 667 } 668 group->overflow_event = &oevent->fse; 669 fsnotify_init_event(group->overflow_event); 670 oevent->mask = FS_Q_OVERFLOW; 671 oevent->wd = -1; 672 oevent->sync_cookie = 0; 673 oevent->name_len = 0; 674 675 group->max_events = max_events; 676 group->memcg = get_mem_cgroup_from_mm(current->mm); 677 678 spin_lock_init(&group->inotify_data.idr_lock); 679 idr_init(&group->inotify_data.idr); 680 group->inotify_data.ucounts = inc_ucount(current_user_ns(), 681 current_euid(), 682 UCOUNT_INOTIFY_INSTANCES); 683 684 if (!group->inotify_data.ucounts) { 685 fsnotify_destroy_group(group); 686 return ERR_PTR(-EMFILE); 687 } 688 689 return group; 690} 691 692 693/* inotify syscalls */ 694static int do_inotify_init(int flags) 695{ 696 struct fsnotify_group *group; 697 int ret; 698 699 /* Check the IN_* constants for consistency. */ 700 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); 701 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); 702 703 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) 704 return -EINVAL; 705 706 /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ 707 group = inotify_new_group(inotify_max_queued_events); 708 if (IS_ERR(group)) 709 return PTR_ERR(group); 710 711 ret = anon_inode_getfd("inotify", &inotify_fops, group, 712 O_RDONLY | flags); 713 if (ret < 0) 714 fsnotify_destroy_group(group); 715 716 return ret; 717} 718 719SYSCALL_DEFINE1(inotify_init1, int, flags) 720{ 721 return do_inotify_init(flags); 722} 723 724SYSCALL_DEFINE0(inotify_init) 725{ 726 return do_inotify_init(0); 727} 728 729SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, 730 u32, mask) 731{ 732 struct fsnotify_group *group; 733 struct inode *inode; 734 struct path path; 735 struct fd f; 736 int ret; 737 unsigned flags = 0; 738 739 /* 740 * We share a lot of code with fs/dnotify. We also share 741 * the bit layout between inotify's IN_* and the fsnotify 742 * FS_*. This check ensures that only the inotify IN_* 743 * bits get passed in and set in watches/events. 744 */ 745 if (unlikely(mask & ~ALL_INOTIFY_BITS)) 746 return -EINVAL; 747 /* 748 * Require at least one valid bit set in the mask. 749 * Without _something_ set, we would have no events to 750 * watch for. 751 */ 752 if (unlikely(!(mask & ALL_INOTIFY_BITS))) 753 return -EINVAL; 754 755 f = fdget(fd); 756 if (unlikely(!f.file)) 757 return -EBADF; 758 759 /* IN_MASK_ADD and IN_MASK_CREATE don't make sense together */ 760 if (unlikely((mask & IN_MASK_ADD) && (mask & IN_MASK_CREATE))) { 761 ret = -EINVAL; 762 goto fput_and_out; 763 } 764 765 /* verify that this is indeed an inotify instance */ 766 if (unlikely(f.file->f_op != &inotify_fops)) { 767 ret = -EINVAL; 768 goto fput_and_out; 769 } 770 771 if (!(mask & IN_DONT_FOLLOW)) 772 flags |= LOOKUP_FOLLOW; 773 if (mask & IN_ONLYDIR) 774 flags |= LOOKUP_DIRECTORY; 775 776 ret = inotify_find_inode(pathname, &path, flags, 777 (mask & IN_ALL_EVENTS)); 778 if (ret) 779 goto fput_and_out; 780 781 /* inode held in place by reference to path; group by fget on fd */ 782 inode = path.dentry->d_inode; 783 group = f.file->private_data; 784 785 /* create/update an inode mark */ 786 ret = inotify_update_watch(group, inode, mask); 787 path_put(&path); 788fput_and_out: 789 fdput(f); 790 return ret; 791} 792 793SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) 794{ 795 struct fsnotify_group *group; 796 struct inotify_inode_mark *i_mark; 797 struct fd f; 798 int ret = -EINVAL; 799 800 f = fdget(fd); 801 if (unlikely(!f.file)) 802 return -EBADF; 803 804 /* verify that this is indeed an inotify instance */ 805 if (unlikely(f.file->f_op != &inotify_fops)) 806 goto out; 807 808 group = f.file->private_data; 809 810 i_mark = inotify_idr_find(group, wd); 811 if (unlikely(!i_mark)) 812 goto out; 813 814 ret = 0; 815 816 fsnotify_destroy_mark(&i_mark->fsn_mark, group); 817 818 /* match ref taken by inotify_idr_find */ 819 fsnotify_put_mark(&i_mark->fsn_mark); 820 821out: 822 fdput(f); 823 return ret; 824} 825 826/* 827 * inotify_user_setup - Our initialization function. Note that we cannot return 828 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 829 * must result in panic(). 830 */ 831static int __init inotify_user_setup(void) 832{ 833 unsigned long watches_max; 834 struct sysinfo si; 835 836 si_meminfo(&si); 837 /* 838 * Allow up to 1% of addressable memory to be allocated for inotify 839 * watches (per user) limited to the range [8192, 1048576]. 840 */ 841 watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) / 842 INOTIFY_WATCH_COST; 843 watches_max = clamp(watches_max, 8192UL, 1048576UL); 844 845 BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); 846 BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); 847 BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); 848 BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); 849 BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); 850 BUILD_BUG_ON(IN_OPEN != FS_OPEN); 851 BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); 852 BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); 853 BUILD_BUG_ON(IN_CREATE != FS_CREATE); 854 BUILD_BUG_ON(IN_DELETE != FS_DELETE); 855 BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); 856 BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); 857 BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); 858 BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); 859 BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); 860 BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); 861 862 BUILD_BUG_ON(HWEIGHT32(ALL_INOTIFY_BITS) != 22); 863 864 inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, 865 SLAB_PANIC|SLAB_ACCOUNT); 866 867 inotify_max_queued_events = 16384; 868 init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128; 869 init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = watches_max; 870 inotify_sysctls_init(); 871 872 return 0; 873} 874fs_initcall(inotify_user_setup); 875