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/dcache.h> /* d_unlinked */
26#include <linux/fs.h> /* struct inode */
27#include <linux/fsnotify_backend.h>
28#include <linux/inotify.h>
29#include <linux/path.h> /* struct path */
30#include <linux/slab.h> /* kmem_* */
31#include <linux/types.h>
32#include <linux/sched.h>
33
34#include "inotify.h"
35
36/*
37 * Check if 2 events contain the same information.
38 */
39static bool event_compare(struct fsnotify_event *old_fsn,
40			  struct fsnotify_event *new_fsn)
41{
42	struct inotify_event_info *old, *new;
43
44	if (old_fsn->mask & FS_IN_IGNORED)
45		return false;
46	old = INOTIFY_E(old_fsn);
47	new = INOTIFY_E(new_fsn);
48	if ((old_fsn->mask == new_fsn->mask) &&
49	    (old_fsn->inode == new_fsn->inode) &&
50	    (old->name_len == new->name_len) &&
51	    (!old->name_len || !strcmp(old->name, new->name)))
52		return true;
53	return false;
54}
55
56static int inotify_merge(struct list_head *list,
57			  struct fsnotify_event *event)
58{
59	struct fsnotify_event *last_event;
60
61	last_event = list_entry(list->prev, struct fsnotify_event, list);
62	return event_compare(last_event, event);
63}
64
65int inotify_handle_event(struct fsnotify_group *group,
66			 struct inode *inode,
67			 struct fsnotify_mark *inode_mark,
68			 struct fsnotify_mark *vfsmount_mark,
69			 u32 mask, void *data, int data_type,
70			 const unsigned char *file_name, u32 cookie)
71{
72	struct inotify_inode_mark *i_mark;
73	struct inotify_event_info *event;
74	struct fsnotify_event *fsn_event;
75	int ret;
76	int len = 0;
77	int alloc_len = sizeof(struct inotify_event_info);
78
79	BUG_ON(vfsmount_mark);
80
81	if ((inode_mark->mask & FS_EXCL_UNLINK) &&
82	    (data_type == FSNOTIFY_EVENT_PATH)) {
83		struct path *path = data;
84
85		if (d_unlinked(path->dentry))
86			return 0;
87	}
88	if (file_name) {
89		len = strlen(file_name);
90		alloc_len += len + 1;
91	}
92
93	pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
94		 mask);
95
96	i_mark = container_of(inode_mark, struct inotify_inode_mark,
97			      fsn_mark);
98
99	event = kmalloc(alloc_len, GFP_KERNEL);
100	if (unlikely(!event))
101		return -ENOMEM;
102
103	fsn_event = &event->fse;
104	fsnotify_init_event(fsn_event, inode, mask);
105	event->wd = i_mark->wd;
106	event->sync_cookie = cookie;
107	event->name_len = len;
108	if (len)
109		strcpy(event->name, file_name);
110
111	ret = fsnotify_add_event(group, fsn_event, inotify_merge);
112	if (ret) {
113		/* Our event wasn't used in the end. Free it. */
114		fsnotify_destroy_event(group, fsn_event);
115	}
116
117	if (inode_mark->mask & IN_ONESHOT)
118		fsnotify_destroy_mark(inode_mark, group);
119
120	return 0;
121}
122
123static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
124{
125	inotify_ignored_and_remove_idr(fsn_mark, group);
126}
127
128/*
129 * This is NEVER supposed to be called.  Inotify marks should either have been
130 * removed from the idr when the watch was removed or in the
131 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
132 * torn down.  This is only called if the idr is about to be freed but there
133 * are still marks in it.
134 */
135static int idr_callback(int id, void *p, void *data)
136{
137	struct fsnotify_mark *fsn_mark;
138	struct inotify_inode_mark *i_mark;
139	static bool warned = false;
140
141	if (warned)
142		return 0;
143
144	warned = true;
145	fsn_mark = p;
146	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
147
148	WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
149		"idr.  Probably leaking memory\n", id, p, data);
150
151	/*
152	 * I'm taking the liberty of assuming that the mark in question is a
153	 * valid address and I'm dereferencing it.  This might help to figure
154	 * out why we got here and the panic is no worse than the original
155	 * BUG() that was here.
156	 */
157	if (fsn_mark)
158		printk(KERN_WARNING "fsn_mark->group=%p inode=%p wd=%d\n",
159			fsn_mark->group, fsn_mark->inode, i_mark->wd);
160	return 0;
161}
162
163static void inotify_free_group_priv(struct fsnotify_group *group)
164{
165	/* ideally the idr is empty and we won't hit the BUG in the callback */
166	idr_for_each(&group->inotify_data.idr, idr_callback, group);
167	idr_destroy(&group->inotify_data.idr);
168	if (group->inotify_data.user) {
169		atomic_dec(&group->inotify_data.user->inotify_devs);
170		free_uid(group->inotify_data.user);
171	}
172}
173
174static void inotify_free_event(struct fsnotify_event *fsn_event)
175{
176	kfree(INOTIFY_E(fsn_event));
177}
178
179const struct fsnotify_ops inotify_fsnotify_ops = {
180	.handle_event = inotify_handle_event,
181	.free_group_priv = inotify_free_group_priv,
182	.free_event = inotify_free_event,
183	.freeing_mark = inotify_freeing_mark,
184};
185