1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * fs/inotify_user.c - inotify support for userspace
6 * John McCutchan <ttb@tentacle.dhs.org>
7 * Robert Love <rml@novell.com>
9 * Copyright (C) 2005 John McCutchan
10 * Copyright 2006 Hewlett-Packard Development Company, L.P.
12 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
13 * inotify was largely rewriten to make use of the fsnotify infrastructure
16 #include <linux/dcache.h> /* d_unlinked */
17 #include <linux/fs.h> /* struct inode */
18 #include <linux/fsnotify_backend.h>
19 #include <linux/inotify.h>
20 #include <linux/path.h> /* struct path */
21 #include <linux/slab.h> /* kmem_* */
22 #include <linux/types.h>
23 #include <linux/sched.h>
24 #include <linux/sched/user.h>
25 #include <linux/sched/mm.h>
30 * Check if 2 events contain the same information.
32 static bool event_compare(struct fsnotify_event *old_fsn,
33 struct fsnotify_event *new_fsn)
35 struct inotify_event_info *old, *new;
37 old = INOTIFY_E(old_fsn);
38 new = INOTIFY_E(new_fsn);
39 if (old->mask & FS_IN_IGNORED)
41 if ((old->mask == new->mask) &&
42 (old->wd == new->wd) &&
43 (old->name_len == new->name_len) &&
44 (!old->name_len || !strcmp(old->name, new->name)))
49 static int inotify_merge(struct fsnotify_group *group,
50 struct fsnotify_event *event)
52 struct list_head *list = &group->notification_list;
53 struct fsnotify_event *last_event;
55 last_event = list_entry(list->prev, struct fsnotify_event, list);
56 return event_compare(last_event, event);
59 int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
60 struct inode *inode, struct inode *dir,
61 const struct qstr *name, u32 cookie)
63 struct inotify_inode_mark *i_mark;
64 struct inotify_event_info *event;
65 struct fsnotify_event *fsn_event;
66 struct fsnotify_group *group = inode_mark->group;
69 int alloc_len = sizeof(struct inotify_event_info);
70 struct mem_cgroup *old_memcg;
77 pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
80 i_mark = container_of(inode_mark, struct inotify_inode_mark,
84 * Whoever is interested in the event, pays for the allocation. Do not
85 * trigger OOM killer in the target monitoring memcg as it may have
86 * security repercussion.
88 old_memcg = set_active_memcg(group->memcg);
89 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
90 set_active_memcg(old_memcg);
92 if (unlikely(!event)) {
94 * Treat lost event due to ENOMEM the same way as queue
95 * overflow to let userspace know event was lost.
97 fsnotify_queue_overflow(group);
102 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
103 * for fanotify. inotify never reported IN_ISDIR with those events.
104 * It looks like an oversight, but to avoid the risk of breaking
105 * existing inotify programs, mask the flag out from those events.
107 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
110 fsn_event = &event->fse;
111 fsnotify_init_event(fsn_event);
113 event->wd = i_mark->wd;
114 event->sync_cookie = cookie;
115 event->name_len = len;
117 strcpy(event->name, name->name);
119 ret = fsnotify_add_event(group, fsn_event, inotify_merge, NULL);
121 /* Our event wasn't used in the end. Free it. */
122 fsnotify_destroy_event(group, fsn_event);
125 if (inode_mark->mask & IN_ONESHOT)
126 fsnotify_destroy_mark(inode_mark, group);
131 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
133 inotify_ignored_and_remove_idr(fsn_mark, group);
137 * This is NEVER supposed to be called. Inotify marks should either have been
138 * removed from the idr when the watch was removed or in the
139 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
140 * torn down. This is only called if the idr is about to be freed but there
141 * are still marks in it.
143 static int idr_callback(int id, void *p, void *data)
145 struct fsnotify_mark *fsn_mark;
146 struct inotify_inode_mark *i_mark;
147 static bool warned = false;
154 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
156 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
157 "idr. Probably leaking memory\n", id, p, data);
160 * I'm taking the liberty of assuming that the mark in question is a
161 * valid address and I'm dereferencing it. This might help to figure
162 * out why we got here and the panic is no worse than the original
163 * BUG() that was here.
166 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
167 fsn_mark->group, i_mark->wd);
171 static void inotify_free_group_priv(struct fsnotify_group *group)
173 /* ideally the idr is empty and we won't hit the BUG in the callback */
174 idr_for_each(&group->inotify_data.idr, idr_callback, group);
175 idr_destroy(&group->inotify_data.idr);
176 if (group->inotify_data.ucounts)
177 dec_inotify_instances(group->inotify_data.ucounts);
180 static void inotify_free_event(struct fsnotify_event *fsn_event)
182 kfree(INOTIFY_E(fsn_event));
185 /* ding dong the mark is dead */
186 static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
188 struct inotify_inode_mark *i_mark;
190 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
192 kmem_cache_free(inotify_inode_mark_cachep, i_mark);
195 const struct fsnotify_ops inotify_fsnotify_ops = {
196 .handle_inode_event = inotify_handle_inode_event,
197 .free_group_priv = inotify_free_group_priv,
198 .free_event = inotify_free_event,
199 .freeing_mark = inotify_freeing_mark,
200 .free_mark = inotify_free_mark,