inotify_fsnotify.c 5.6 KB

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  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. #include <linux/dcache.h> /* d_unlinked */
  16. #include <linux/fs.h> /* struct inode */
  17. #include <linux/fsnotify_backend.h>
  18. #include <linux/inotify.h>
  19. #include <linux/path.h> /* struct path */
  20. #include <linux/slab.h> /* kmem_* */
  21. #include <linux/types.h>
  22. #include <linux/sched.h>
  23. #include <linux/sched/user.h>
  24. #include <linux/sched/mm.h>
  25. #include "inotify.h"
  26. /*
  27. * Check if 2 events contain the same information.
  28. */
  29. static bool event_compare(struct fsnotify_event *old_fsn,
  30. struct fsnotify_event *new_fsn)
  31. {
  32. struct inotify_event_info *old, *new;
  33. old = INOTIFY_E(old_fsn);
  34. new = INOTIFY_E(new_fsn);
  35. if (old->mask & FS_IN_IGNORED)
  36. return false;
  37. if ((old->mask == new->mask) &&
  38. (old->wd == new->wd) &&
  39. (old->name_len == new->name_len) &&
  40. (!old->name_len || !strcmp(old->name, new->name)))
  41. return true;
  42. return false;
  43. }
  44. static int inotify_merge(struct list_head *list,
  45. struct fsnotify_event *event)
  46. {
  47. struct fsnotify_event *last_event;
  48. last_event = list_entry(list->prev, struct fsnotify_event, list);
  49. return event_compare(last_event, event);
  50. }
  51. int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
  52. struct inode *inode, struct inode *dir,
  53. const struct qstr *name, u32 cookie)
  54. {
  55. struct inotify_inode_mark *i_mark;
  56. struct inotify_event_info *event;
  57. struct fsnotify_event *fsn_event;
  58. struct fsnotify_group *group = inode_mark->group;
  59. int ret;
  60. int len = 0;
  61. int alloc_len = sizeof(struct inotify_event_info);
  62. struct mem_cgroup *old_memcg;
  63. if (name) {
  64. len = name->len;
  65. alloc_len += len + 1;
  66. }
  67. pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
  68. mask);
  69. i_mark = container_of(inode_mark, struct inotify_inode_mark,
  70. fsn_mark);
  71. /*
  72. * Whoever is interested in the event, pays for the allocation. Do not
  73. * trigger OOM killer in the target monitoring memcg as it may have
  74. * security repercussion.
  75. */
  76. old_memcg = set_active_memcg(group->memcg);
  77. event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
  78. set_active_memcg(old_memcg);
  79. if (unlikely(!event)) {
  80. /*
  81. * Treat lost event due to ENOMEM the same way as queue
  82. * overflow to let userspace know event was lost.
  83. */
  84. fsnotify_queue_overflow(group);
  85. return -ENOMEM;
  86. }
  87. /*
  88. * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
  89. * for fanotify. inotify never reported IN_ISDIR with those events.
  90. * It looks like an oversight, but to avoid the risk of breaking
  91. * existing inotify programs, mask the flag out from those events.
  92. */
  93. if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
  94. mask &= ~IN_ISDIR;
  95. fsn_event = &event->fse;
  96. fsnotify_init_event(fsn_event, 0);
  97. event->mask = mask;
  98. event->wd = i_mark->wd;
  99. event->sync_cookie = cookie;
  100. event->name_len = len;
  101. if (len)
  102. strcpy(event->name, name->name);
  103. ret = fsnotify_add_event(group, fsn_event, inotify_merge);
  104. if (ret) {
  105. /* Our event wasn't used in the end. Free it. */
  106. fsnotify_destroy_event(group, fsn_event);
  107. }
  108. if (inode_mark->mask & IN_ONESHOT)
  109. fsnotify_destroy_mark(inode_mark, group);
  110. return 0;
  111. }
  112. static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
  113. {
  114. inotify_ignored_and_remove_idr(fsn_mark, group);
  115. }
  116. /*
  117. * This is NEVER supposed to be called. Inotify marks should either have been
  118. * removed from the idr when the watch was removed or in the
  119. * fsnotify_destroy_mark_by_group() call when the inotify instance was being
  120. * torn down. This is only called if the idr is about to be freed but there
  121. * are still marks in it.
  122. */
  123. static int idr_callback(int id, void *p, void *data)
  124. {
  125. struct fsnotify_mark *fsn_mark;
  126. struct inotify_inode_mark *i_mark;
  127. static bool warned = false;
  128. if (warned)
  129. return 0;
  130. warned = true;
  131. fsn_mark = p;
  132. i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
  133. WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
  134. "idr. Probably leaking memory\n", id, p, data);
  135. /*
  136. * I'm taking the liberty of assuming that the mark in question is a
  137. * valid address and I'm dereferencing it. This might help to figure
  138. * out why we got here and the panic is no worse than the original
  139. * BUG() that was here.
  140. */
  141. if (fsn_mark)
  142. printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
  143. fsn_mark->group, i_mark->wd);
  144. return 0;
  145. }
  146. static void inotify_free_group_priv(struct fsnotify_group *group)
  147. {
  148. /* ideally the idr is empty and we won't hit the BUG in the callback */
  149. idr_for_each(&group->inotify_data.idr, idr_callback, group);
  150. idr_destroy(&group->inotify_data.idr);
  151. if (group->inotify_data.ucounts)
  152. dec_inotify_instances(group->inotify_data.ucounts);
  153. }
  154. static void inotify_free_event(struct fsnotify_event *fsn_event)
  155. {
  156. kfree(INOTIFY_E(fsn_event));
  157. }
  158. /* ding dong the mark is dead */
  159. static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
  160. {
  161. struct inotify_inode_mark *i_mark;
  162. i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
  163. kmem_cache_free(inotify_inode_mark_cachep, i_mark);
  164. }
  165. const struct fsnotify_ops inotify_fsnotify_ops = {
  166. .handle_inode_event = inotify_handle_inode_event,
  167. .free_group_priv = inotify_free_group_priv,
  168. .free_event = inotify_free_event,
  169. .freeing_mark = inotify_freeing_mark,
  170. .free_mark = inotify_free_mark,
  171. };