1 /* 2 * fs/inotify_user.c - inotify support for userspace 3 * 4 * Authors: 5 * John McCutchan <ttb@tentacle.dhs.org> 6 * Robert Love <rml@novell.com> 7 * 8 * Copyright (C) 2005 John McCutchan 9 * Copyright 2006 Hewlett-Packard Development Company, L.P. 10 * 11 * Copyright (C) 2009 Eric Paris <Red Hat Inc> 12 * inotify was largely rewriten to make use of the fsnotify infrastructure 13 * 14 * This program is free software; you can redistribute it and/or modify it 15 * under the terms of the GNU General Public License as published by the 16 * Free Software Foundation; either version 2, or (at your option) any 17 * later version. 18 * 19 * This program is distributed in the hope that it will be useful, but 20 * WITHOUT ANY WARRANTY; without even the implied warranty of 21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 * General Public License for more details. 23 */ 24 25 #include <linux/file.h> 26 #include <linux/fs.h> /* struct inode */ 27 #include <linux/fsnotify_backend.h> 28 #include <linux/idr.h> 29 #include <linux/init.h> /* module_init */ 30 #include <linux/inotify.h> 31 #include <linux/kernel.h> /* roundup() */ 32 #include <linux/namei.h> /* LOOKUP_FOLLOW */ 33 #include <linux/sched.h> /* struct user */ 34 #include <linux/slab.h> /* struct kmem_cache */ 35 #include <linux/syscalls.h> 36 #include <linux/types.h> 37 #include <linux/anon_inodes.h> 38 #include <linux/uaccess.h> 39 #include <linux/poll.h> 40 #include <linux/wait.h> 41 42 #include "inotify.h" 43 44 #include <asm/ioctls.h> 45 46 /* these are configurable via /proc/sys/fs/inotify/ */ 47 static int inotify_max_user_instances __read_mostly; 48 static int inotify_max_queued_events __read_mostly; 49 static int inotify_max_user_watches __read_mostly; 50 51 static struct kmem_cache *inotify_inode_mark_cachep __read_mostly; 52 struct kmem_cache *event_priv_cachep __read_mostly; 53 54 #ifdef CONFIG_SYSCTL 55 56 #include <linux/sysctl.h> 57 58 static int zero; 59 60 ctl_table inotify_table[] = { 61 { 62 .procname = "max_user_instances", 63 .data = &inotify_max_user_instances, 64 .maxlen = sizeof(int), 65 .mode = 0644, 66 .proc_handler = proc_dointvec_minmax, 67 .extra1 = &zero, 68 }, 69 { 70 .procname = "max_user_watches", 71 .data = &inotify_max_user_watches, 72 .maxlen = sizeof(int), 73 .mode = 0644, 74 .proc_handler = proc_dointvec_minmax, 75 .extra1 = &zero, 76 }, 77 { 78 .procname = "max_queued_events", 79 .data = &inotify_max_queued_events, 80 .maxlen = sizeof(int), 81 .mode = 0644, 82 .proc_handler = proc_dointvec_minmax, 83 .extra1 = &zero 84 }, 85 { } 86 }; 87 #endif /* CONFIG_SYSCTL */ 88 89 static inline __u32 inotify_arg_to_mask(u32 arg) 90 { 91 __u32 mask; 92 93 /* 94 * everything should accept their own ignored, cares about children, 95 * and should receive events when the inode is unmounted 96 */ 97 mask = (FS_IN_IGNORED | FS_EVENT_ON_CHILD | FS_UNMOUNT); 98 99 /* mask off the flags used to open the fd */ 100 mask |= (arg & (IN_ALL_EVENTS | IN_ONESHOT | IN_EXCL_UNLINK)); 101 102 return mask; 103 } 104 105 static inline u32 inotify_mask_to_arg(__u32 mask) 106 { 107 return mask & (IN_ALL_EVENTS | IN_ISDIR | IN_UNMOUNT | IN_IGNORED | 108 IN_Q_OVERFLOW); 109 } 110 111 /* intofiy userspace file descriptor functions */ 112 static unsigned int inotify_poll(struct file *file, poll_table *wait) 113 { 114 struct fsnotify_group *group = file->private_data; 115 int ret = 0; 116 117 poll_wait(file, &group->notification_waitq, wait); 118 mutex_lock(&group->notification_mutex); 119 if (!fsnotify_notify_queue_is_empty(group)) 120 ret = POLLIN | POLLRDNORM; 121 mutex_unlock(&group->notification_mutex); 122 123 return ret; 124 } 125 126 /* 127 * Get an inotify_kernel_event if one exists and is small 128 * enough to fit in "count". Return an error pointer if 129 * not large enough. 130 * 131 * Called with the group->notification_mutex held. 132 */ 133 static struct fsnotify_event *get_one_event(struct fsnotify_group *group, 134 size_t count) 135 { 136 size_t event_size = sizeof(struct inotify_event); 137 struct fsnotify_event *event; 138 139 if (fsnotify_notify_queue_is_empty(group)) 140 return NULL; 141 142 event = fsnotify_peek_notify_event(group); 143 144 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 145 146 if (event->name_len) 147 event_size += roundup(event->name_len + 1, event_size); 148 149 if (event_size > count) 150 return ERR_PTR(-EINVAL); 151 152 /* held the notification_mutex the whole time, so this is the 153 * same event we peeked above */ 154 fsnotify_remove_notify_event(group); 155 156 return event; 157 } 158 159 /* 160 * Copy an event to user space, returning how much we copied. 161 * 162 * We already checked that the event size is smaller than the 163 * buffer we had in "get_one_event()" above. 164 */ 165 static ssize_t copy_event_to_user(struct fsnotify_group *group, 166 struct fsnotify_event *event, 167 char __user *buf) 168 { 169 struct inotify_event inotify_event; 170 struct fsnotify_event_private_data *fsn_priv; 171 struct inotify_event_private_data *priv; 172 size_t event_size = sizeof(struct inotify_event); 173 size_t name_len = 0; 174 175 pr_debug("%s: group=%p event=%p\n", __func__, group, event); 176 177 /* we get the inotify watch descriptor from the event private data */ 178 spin_lock(&event->lock); 179 fsn_priv = fsnotify_remove_priv_from_event(group, event); 180 spin_unlock(&event->lock); 181 182 if (!fsn_priv) 183 inotify_event.wd = -1; 184 else { 185 priv = container_of(fsn_priv, struct inotify_event_private_data, 186 fsnotify_event_priv_data); 187 inotify_event.wd = priv->wd; 188 inotify_free_event_priv(fsn_priv); 189 } 190 191 /* 192 * round up event->name_len so it is a multiple of event_size 193 * plus an extra byte for the terminating '\0'. 194 */ 195 if (event->name_len) 196 name_len = roundup(event->name_len + 1, event_size); 197 inotify_event.len = name_len; 198 199 inotify_event.mask = inotify_mask_to_arg(event->mask); 200 inotify_event.cookie = event->sync_cookie; 201 202 /* send the main event */ 203 if (copy_to_user(buf, &inotify_event, event_size)) 204 return -EFAULT; 205 206 buf += event_size; 207 208 /* 209 * fsnotify only stores the pathname, so here we have to send the pathname 210 * and then pad that pathname out to a multiple of sizeof(inotify_event) 211 * with zeros. I get my zeros from the nul_inotify_event. 212 */ 213 if (name_len) { 214 unsigned int len_to_zero = name_len - event->name_len; 215 /* copy the path name */ 216 if (copy_to_user(buf, event->file_name, event->name_len)) 217 return -EFAULT; 218 buf += event->name_len; 219 220 /* fill userspace with 0's */ 221 if (clear_user(buf, len_to_zero)) 222 return -EFAULT; 223 buf += len_to_zero; 224 event_size += name_len; 225 } 226 227 return event_size; 228 } 229 230 static ssize_t inotify_read(struct file *file, char __user *buf, 231 size_t count, loff_t *pos) 232 { 233 struct fsnotify_group *group; 234 struct fsnotify_event *kevent; 235 char __user *start; 236 int ret; 237 DEFINE_WAIT(wait); 238 239 start = buf; 240 group = file->private_data; 241 242 while (1) { 243 prepare_to_wait(&group->notification_waitq, &wait, TASK_INTERRUPTIBLE); 244 245 mutex_lock(&group->notification_mutex); 246 kevent = get_one_event(group, count); 247 mutex_unlock(&group->notification_mutex); 248 249 pr_debug("%s: group=%p kevent=%p\n", __func__, group, kevent); 250 251 if (kevent) { 252 ret = PTR_ERR(kevent); 253 if (IS_ERR(kevent)) 254 break; 255 ret = copy_event_to_user(group, kevent, buf); 256 fsnotify_put_event(kevent); 257 if (ret < 0) 258 break; 259 buf += ret; 260 count -= ret; 261 continue; 262 } 263 264 ret = -EAGAIN; 265 if (file->f_flags & O_NONBLOCK) 266 break; 267 ret = -EINTR; 268 if (signal_pending(current)) 269 break; 270 271 if (start != buf) 272 break; 273 274 schedule(); 275 } 276 277 finish_wait(&group->notification_waitq, &wait); 278 if (start != buf && ret != -EFAULT) 279 ret = buf - start; 280 return ret; 281 } 282 283 static int inotify_fasync(int fd, struct file *file, int on) 284 { 285 struct fsnotify_group *group = file->private_data; 286 287 return fasync_helper(fd, file, on, &group->inotify_data.fa) >= 0 ? 0 : -EIO; 288 } 289 290 static int inotify_release(struct inode *ignored, struct file *file) 291 { 292 struct fsnotify_group *group = file->private_data; 293 struct user_struct *user = group->inotify_data.user; 294 295 pr_debug("%s: group=%p\n", __func__, group); 296 297 fsnotify_clear_marks_by_group(group); 298 299 /* free this group, matching get was inotify_init->fsnotify_obtain_group */ 300 fsnotify_put_group(group); 301 302 atomic_dec(&user->inotify_devs); 303 304 return 0; 305 } 306 307 static long inotify_ioctl(struct file *file, unsigned int cmd, 308 unsigned long arg) 309 { 310 struct fsnotify_group *group; 311 struct fsnotify_event_holder *holder; 312 struct fsnotify_event *event; 313 void __user *p; 314 int ret = -ENOTTY; 315 size_t send_len = 0; 316 317 group = file->private_data; 318 p = (void __user *) arg; 319 320 pr_debug("%s: group=%p cmd=%u\n", __func__, group, cmd); 321 322 switch (cmd) { 323 case FIONREAD: 324 mutex_lock(&group->notification_mutex); 325 list_for_each_entry(holder, &group->notification_list, event_list) { 326 event = holder->event; 327 send_len += sizeof(struct inotify_event); 328 if (event->name_len) 329 send_len += roundup(event->name_len + 1, 330 sizeof(struct inotify_event)); 331 } 332 mutex_unlock(&group->notification_mutex); 333 ret = put_user(send_len, (int __user *) p); 334 break; 335 } 336 337 return ret; 338 } 339 340 static const struct file_operations inotify_fops = { 341 .poll = inotify_poll, 342 .read = inotify_read, 343 .fasync = inotify_fasync, 344 .release = inotify_release, 345 .unlocked_ioctl = inotify_ioctl, 346 .compat_ioctl = inotify_ioctl, 347 .llseek = noop_llseek, 348 }; 349 350 351 /* 352 * find_inode - resolve a user-given path to a specific inode 353 */ 354 static int inotify_find_inode(const char __user *dirname, struct path *path, unsigned flags) 355 { 356 int error; 357 358 error = user_path_at(AT_FDCWD, dirname, flags, path); 359 if (error) 360 return error; 361 /* you can only watch an inode if you have read permissions on it */ 362 error = inode_permission(path->dentry->d_inode, MAY_READ); 363 if (error) 364 path_put(path); 365 return error; 366 } 367 368 static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock, 369 int *last_wd, 370 struct inotify_inode_mark *i_mark) 371 { 372 int ret; 373 374 do { 375 if (unlikely(!idr_pre_get(idr, GFP_KERNEL))) 376 return -ENOMEM; 377 378 spin_lock(idr_lock); 379 ret = idr_get_new_above(idr, i_mark, *last_wd + 1, 380 &i_mark->wd); 381 /* we added the mark to the idr, take a reference */ 382 if (!ret) { 383 *last_wd = i_mark->wd; 384 fsnotify_get_mark(&i_mark->fsn_mark); 385 } 386 spin_unlock(idr_lock); 387 } while (ret == -EAGAIN); 388 389 return ret; 390 } 391 392 static struct inotify_inode_mark *inotify_idr_find_locked(struct fsnotify_group *group, 393 int wd) 394 { 395 struct idr *idr = &group->inotify_data.idr; 396 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 397 struct inotify_inode_mark *i_mark; 398 399 assert_spin_locked(idr_lock); 400 401 i_mark = idr_find(idr, wd); 402 if (i_mark) { 403 struct fsnotify_mark *fsn_mark = &i_mark->fsn_mark; 404 405 fsnotify_get_mark(fsn_mark); 406 /* One ref for being in the idr, one ref we just took */ 407 BUG_ON(atomic_read(&fsn_mark->refcnt) < 2); 408 } 409 410 return i_mark; 411 } 412 413 static struct inotify_inode_mark *inotify_idr_find(struct fsnotify_group *group, 414 int wd) 415 { 416 struct inotify_inode_mark *i_mark; 417 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 418 419 spin_lock(idr_lock); 420 i_mark = inotify_idr_find_locked(group, wd); 421 spin_unlock(idr_lock); 422 423 return i_mark; 424 } 425 426 static void do_inotify_remove_from_idr(struct fsnotify_group *group, 427 struct inotify_inode_mark *i_mark) 428 { 429 struct idr *idr = &group->inotify_data.idr; 430 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 431 int wd = i_mark->wd; 432 433 assert_spin_locked(idr_lock); 434 435 idr_remove(idr, wd); 436 437 /* removed from the idr, drop that ref */ 438 fsnotify_put_mark(&i_mark->fsn_mark); 439 } 440 441 /* 442 * Remove the mark from the idr (if present) and drop the reference 443 * on the mark because it was in the idr. 444 */ 445 static void inotify_remove_from_idr(struct fsnotify_group *group, 446 struct inotify_inode_mark *i_mark) 447 { 448 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 449 struct inotify_inode_mark *found_i_mark = NULL; 450 int wd; 451 452 spin_lock(idr_lock); 453 wd = i_mark->wd; 454 455 /* 456 * does this i_mark think it is in the idr? we shouldn't get called 457 * if it wasn't.... 458 */ 459 if (wd == -1) { 460 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" 461 " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, 462 i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); 463 goto out; 464 } 465 466 /* Lets look in the idr to see if we find it */ 467 found_i_mark = inotify_idr_find_locked(group, wd); 468 if (unlikely(!found_i_mark)) { 469 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" 470 " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, 471 i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); 472 goto out; 473 } 474 475 /* 476 * We found an mark in the idr at the right wd, but it's 477 * not the mark we were told to remove. eparis seriously 478 * fucked up somewhere. 479 */ 480 if (unlikely(found_i_mark != i_mark)) { 481 WARN_ONCE(1, "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p " 482 "mark->inode=%p found_i_mark=%p found_i_mark->wd=%d " 483 "found_i_mark->group=%p found_i_mark->inode=%p\n", 484 __func__, i_mark, i_mark->wd, i_mark->fsn_mark.group, 485 i_mark->fsn_mark.i.inode, found_i_mark, found_i_mark->wd, 486 found_i_mark->fsn_mark.group, 487 found_i_mark->fsn_mark.i.inode); 488 goto out; 489 } 490 491 /* 492 * One ref for being in the idr 493 * one ref held by the caller trying to kill us 494 * one ref grabbed by inotify_idr_find 495 */ 496 if (unlikely(atomic_read(&i_mark->fsn_mark.refcnt) < 3)) { 497 printk(KERN_ERR "%s: i_mark=%p i_mark->wd=%d i_mark->group=%p" 498 " i_mark->inode=%p\n", __func__, i_mark, i_mark->wd, 499 i_mark->fsn_mark.group, i_mark->fsn_mark.i.inode); 500 /* we can't really recover with bad ref cnting.. */ 501 BUG(); 502 } 503 504 do_inotify_remove_from_idr(group, i_mark); 505 out: 506 /* match the ref taken by inotify_idr_find_locked() */ 507 if (found_i_mark) 508 fsnotify_put_mark(&found_i_mark->fsn_mark); 509 i_mark->wd = -1; 510 spin_unlock(idr_lock); 511 } 512 513 /* 514 * Send IN_IGNORED for this wd, remove this wd from the idr. 515 */ 516 void inotify_ignored_and_remove_idr(struct fsnotify_mark *fsn_mark, 517 struct fsnotify_group *group) 518 { 519 struct inotify_inode_mark *i_mark; 520 struct fsnotify_event *ignored_event, *notify_event; 521 struct inotify_event_private_data *event_priv; 522 struct fsnotify_event_private_data *fsn_event_priv; 523 int ret; 524 525 ignored_event = fsnotify_create_event(NULL, FS_IN_IGNORED, NULL, 526 FSNOTIFY_EVENT_NONE, NULL, 0, 527 GFP_NOFS); 528 if (!ignored_event) 529 return; 530 531 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 532 533 event_priv = kmem_cache_alloc(event_priv_cachep, GFP_NOFS); 534 if (unlikely(!event_priv)) 535 goto skip_send_ignore; 536 537 fsn_event_priv = &event_priv->fsnotify_event_priv_data; 538 539 fsn_event_priv->group = group; 540 event_priv->wd = i_mark->wd; 541 542 notify_event = fsnotify_add_notify_event(group, ignored_event, fsn_event_priv, NULL); 543 if (notify_event) { 544 if (IS_ERR(notify_event)) 545 ret = PTR_ERR(notify_event); 546 else 547 fsnotify_put_event(notify_event); 548 inotify_free_event_priv(fsn_event_priv); 549 } 550 551 skip_send_ignore: 552 553 /* matches the reference taken when the event was created */ 554 fsnotify_put_event(ignored_event); 555 556 /* remove this mark from the idr */ 557 inotify_remove_from_idr(group, i_mark); 558 559 atomic_dec(&group->inotify_data.user->inotify_watches); 560 } 561 562 /* ding dong the mark is dead */ 563 static void inotify_free_mark(struct fsnotify_mark *fsn_mark) 564 { 565 struct inotify_inode_mark *i_mark; 566 567 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 568 569 kmem_cache_free(inotify_inode_mark_cachep, i_mark); 570 } 571 572 static int inotify_update_existing_watch(struct fsnotify_group *group, 573 struct inode *inode, 574 u32 arg) 575 { 576 struct fsnotify_mark *fsn_mark; 577 struct inotify_inode_mark *i_mark; 578 __u32 old_mask, new_mask; 579 __u32 mask; 580 int add = (arg & IN_MASK_ADD); 581 int ret; 582 583 /* don't allow invalid bits: we don't want flags set */ 584 mask = inotify_arg_to_mask(arg); 585 if (unlikely(!(mask & IN_ALL_EVENTS))) 586 return -EINVAL; 587 588 fsn_mark = fsnotify_find_inode_mark(group, inode); 589 if (!fsn_mark) 590 return -ENOENT; 591 592 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark); 593 594 spin_lock(&fsn_mark->lock); 595 596 old_mask = fsn_mark->mask; 597 if (add) 598 fsnotify_set_mark_mask_locked(fsn_mark, (fsn_mark->mask | mask)); 599 else 600 fsnotify_set_mark_mask_locked(fsn_mark, mask); 601 new_mask = fsn_mark->mask; 602 603 spin_unlock(&fsn_mark->lock); 604 605 if (old_mask != new_mask) { 606 /* more bits in old than in new? */ 607 int dropped = (old_mask & ~new_mask); 608 /* more bits in this fsn_mark than the inode's mask? */ 609 int do_inode = (new_mask & ~inode->i_fsnotify_mask); 610 611 /* update the inode with this new fsn_mark */ 612 if (dropped || do_inode) 613 fsnotify_recalc_inode_mask(inode); 614 615 } 616 617 /* return the wd */ 618 ret = i_mark->wd; 619 620 /* match the get from fsnotify_find_mark() */ 621 fsnotify_put_mark(fsn_mark); 622 623 return ret; 624 } 625 626 static int inotify_new_watch(struct fsnotify_group *group, 627 struct inode *inode, 628 u32 arg) 629 { 630 struct inotify_inode_mark *tmp_i_mark; 631 __u32 mask; 632 int ret; 633 struct idr *idr = &group->inotify_data.idr; 634 spinlock_t *idr_lock = &group->inotify_data.idr_lock; 635 636 /* don't allow invalid bits: we don't want flags set */ 637 mask = inotify_arg_to_mask(arg); 638 if (unlikely(!(mask & IN_ALL_EVENTS))) 639 return -EINVAL; 640 641 tmp_i_mark = kmem_cache_alloc(inotify_inode_mark_cachep, GFP_KERNEL); 642 if (unlikely(!tmp_i_mark)) 643 return -ENOMEM; 644 645 fsnotify_init_mark(&tmp_i_mark->fsn_mark, inotify_free_mark); 646 tmp_i_mark->fsn_mark.mask = mask; 647 tmp_i_mark->wd = -1; 648 649 ret = -ENOSPC; 650 if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches) 651 goto out_err; 652 653 ret = inotify_add_to_idr(idr, idr_lock, &group->inotify_data.last_wd, 654 tmp_i_mark); 655 if (ret) 656 goto out_err; 657 658 /* we are on the idr, now get on the inode */ 659 ret = fsnotify_add_mark(&tmp_i_mark->fsn_mark, group, inode, NULL, 0); 660 if (ret) { 661 /* we failed to get on the inode, get off the idr */ 662 inotify_remove_from_idr(group, tmp_i_mark); 663 goto out_err; 664 } 665 666 /* increment the number of watches the user has */ 667 atomic_inc(&group->inotify_data.user->inotify_watches); 668 669 /* return the watch descriptor for this new mark */ 670 ret = tmp_i_mark->wd; 671 672 out_err: 673 /* match the ref from fsnotify_init_mark() */ 674 fsnotify_put_mark(&tmp_i_mark->fsn_mark); 675 676 return ret; 677 } 678 679 static int inotify_update_watch(struct fsnotify_group *group, struct inode *inode, u32 arg) 680 { 681 int ret = 0; 682 683 retry: 684 /* try to update and existing watch with the new arg */ 685 ret = inotify_update_existing_watch(group, inode, arg); 686 /* no mark present, try to add a new one */ 687 if (ret == -ENOENT) 688 ret = inotify_new_watch(group, inode, arg); 689 /* 690 * inotify_new_watch could race with another thread which did an 691 * inotify_new_watch between the update_existing and the add watch 692 * here, go back and try to update an existing mark again. 693 */ 694 if (ret == -EEXIST) 695 goto retry; 696 697 return ret; 698 } 699 700 static struct fsnotify_group *inotify_new_group(struct user_struct *user, unsigned int max_events) 701 { 702 struct fsnotify_group *group; 703 704 group = fsnotify_alloc_group(&inotify_fsnotify_ops); 705 if (IS_ERR(group)) 706 return group; 707 708 group->max_events = max_events; 709 710 spin_lock_init(&group->inotify_data.idr_lock); 711 idr_init(&group->inotify_data.idr); 712 group->inotify_data.last_wd = 0; 713 group->inotify_data.user = user; 714 group->inotify_data.fa = NULL; 715 716 return group; 717 } 718 719 720 /* inotify syscalls */ 721 SYSCALL_DEFINE1(inotify_init1, int, flags) 722 { 723 struct fsnotify_group *group; 724 struct user_struct *user; 725 int ret; 726 727 /* Check the IN_* constants for consistency. */ 728 BUILD_BUG_ON(IN_CLOEXEC != O_CLOEXEC); 729 BUILD_BUG_ON(IN_NONBLOCK != O_NONBLOCK); 730 731 if (flags & ~(IN_CLOEXEC | IN_NONBLOCK)) 732 return -EINVAL; 733 734 user = get_current_user(); 735 if (unlikely(atomic_read(&user->inotify_devs) >= 736 inotify_max_user_instances)) { 737 ret = -EMFILE; 738 goto out_free_uid; 739 } 740 741 /* fsnotify_obtain_group took a reference to group, we put this when we kill the file in the end */ 742 group = inotify_new_group(user, inotify_max_queued_events); 743 if (IS_ERR(group)) { 744 ret = PTR_ERR(group); 745 goto out_free_uid; 746 } 747 748 atomic_inc(&user->inotify_devs); 749 750 ret = anon_inode_getfd("inotify", &inotify_fops, group, 751 O_RDONLY | flags); 752 if (ret >= 0) 753 return ret; 754 755 fsnotify_put_group(group); 756 atomic_dec(&user->inotify_devs); 757 out_free_uid: 758 free_uid(user); 759 return ret; 760 } 761 762 SYSCALL_DEFINE0(inotify_init) 763 { 764 return sys_inotify_init1(0); 765 } 766 767 SYSCALL_DEFINE3(inotify_add_watch, int, fd, const char __user *, pathname, 768 u32, mask) 769 { 770 struct fsnotify_group *group; 771 struct inode *inode; 772 struct path path; 773 struct file *filp; 774 int ret, fput_needed; 775 unsigned flags = 0; 776 777 filp = fget_light(fd, &fput_needed); 778 if (unlikely(!filp)) 779 return -EBADF; 780 781 /* verify that this is indeed an inotify instance */ 782 if (unlikely(filp->f_op != &inotify_fops)) { 783 ret = -EINVAL; 784 goto fput_and_out; 785 } 786 787 if (!(mask & IN_DONT_FOLLOW)) 788 flags |= LOOKUP_FOLLOW; 789 if (mask & IN_ONLYDIR) 790 flags |= LOOKUP_DIRECTORY; 791 792 ret = inotify_find_inode(pathname, &path, flags); 793 if (ret) 794 goto fput_and_out; 795 796 /* inode held in place by reference to path; group by fget on fd */ 797 inode = path.dentry->d_inode; 798 group = filp->private_data; 799 800 /* create/update an inode mark */ 801 ret = inotify_update_watch(group, inode, mask); 802 path_put(&path); 803 fput_and_out: 804 fput_light(filp, fput_needed); 805 return ret; 806 } 807 808 SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd) 809 { 810 struct fsnotify_group *group; 811 struct inotify_inode_mark *i_mark; 812 struct file *filp; 813 int ret = 0, fput_needed; 814 815 filp = fget_light(fd, &fput_needed); 816 if (unlikely(!filp)) 817 return -EBADF; 818 819 /* verify that this is indeed an inotify instance */ 820 ret = -EINVAL; 821 if (unlikely(filp->f_op != &inotify_fops)) 822 goto out; 823 824 group = filp->private_data; 825 826 ret = -EINVAL; 827 i_mark = inotify_idr_find(group, wd); 828 if (unlikely(!i_mark)) 829 goto out; 830 831 ret = 0; 832 833 fsnotify_destroy_mark(&i_mark->fsn_mark); 834 835 /* match ref taken by inotify_idr_find */ 836 fsnotify_put_mark(&i_mark->fsn_mark); 837 838 out: 839 fput_light(filp, fput_needed); 840 return ret; 841 } 842 843 /* 844 * inotify_user_setup - Our initialization function. Note that we cannnot return 845 * error because we have compiled-in VFS hooks. So an (unlikely) failure here 846 * must result in panic(). 847 */ 848 static int __init inotify_user_setup(void) 849 { 850 BUILD_BUG_ON(IN_ACCESS != FS_ACCESS); 851 BUILD_BUG_ON(IN_MODIFY != FS_MODIFY); 852 BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB); 853 BUILD_BUG_ON(IN_CLOSE_WRITE != FS_CLOSE_WRITE); 854 BUILD_BUG_ON(IN_CLOSE_NOWRITE != FS_CLOSE_NOWRITE); 855 BUILD_BUG_ON(IN_OPEN != FS_OPEN); 856 BUILD_BUG_ON(IN_MOVED_FROM != FS_MOVED_FROM); 857 BUILD_BUG_ON(IN_MOVED_TO != FS_MOVED_TO); 858 BUILD_BUG_ON(IN_CREATE != FS_CREATE); 859 BUILD_BUG_ON(IN_DELETE != FS_DELETE); 860 BUILD_BUG_ON(IN_DELETE_SELF != FS_DELETE_SELF); 861 BUILD_BUG_ON(IN_MOVE_SELF != FS_MOVE_SELF); 862 BUILD_BUG_ON(IN_UNMOUNT != FS_UNMOUNT); 863 BUILD_BUG_ON(IN_Q_OVERFLOW != FS_Q_OVERFLOW); 864 BUILD_BUG_ON(IN_IGNORED != FS_IN_IGNORED); 865 BUILD_BUG_ON(IN_EXCL_UNLINK != FS_EXCL_UNLINK); 866 BUILD_BUG_ON(IN_ISDIR != FS_ISDIR); 867 BUILD_BUG_ON(IN_ONESHOT != FS_IN_ONESHOT); 868 869 BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21); 870 871 inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC); 872 event_priv_cachep = KMEM_CACHE(inotify_event_private_data, SLAB_PANIC); 873 874 inotify_max_queued_events = 16384; 875 inotify_max_user_instances = 128; 876 inotify_max_user_watches = 8192; 877 878 return 0; 879 } 880 module_init(inotify_user_setup); 881