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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#include <linux/sched/user.h>
34
35#include "inotify.h"
36
37/*
38 * Check if 2 events contain the same information.
39 */
40static bool event_compare(struct fsnotify_event *old_fsn,
41 struct fsnotify_event *new_fsn)
42{
43 struct inotify_event_info *old, *new;
44
45 if (old_fsn->mask & FS_IN_IGNORED)
46 return false;
47 old = INOTIFY_E(old_fsn);
48 new = INOTIFY_E(new_fsn);
49 if ((old_fsn->mask == new_fsn->mask) &&
50 (old_fsn->inode == new_fsn->inode) &&
51 (old->name_len == new->name_len) &&
52 (!old->name_len || !strcmp(old->name, new->name)))
53 return true;
54 return false;
55}
56
57static int inotify_merge(struct list_head *list,
58 struct fsnotify_event *event)
59{
60 struct fsnotify_event *last_event;
61
62 last_event = list_entry(list->prev, struct fsnotify_event, list);
63 return event_compare(last_event, event);
64}
65
66int inotify_handle_event(struct fsnotify_group *group,
67 struct inode *inode,
68 struct fsnotify_mark *inode_mark,
69 struct fsnotify_mark *vfsmount_mark,
70 u32 mask, const void *data, int data_type,
71 const unsigned char *file_name, u32 cookie,
72 struct fsnotify_iter_info *iter_info)
73{
74 struct inotify_inode_mark *i_mark;
75 struct inotify_event_info *event;
76 struct fsnotify_event *fsn_event;
77 int ret;
78 int len = 0;
79 int alloc_len = sizeof(struct inotify_event_info);
80
81 BUG_ON(vfsmount_mark);
82
83 if ((inode_mark->mask & FS_EXCL_UNLINK) &&
84 (data_type == FSNOTIFY_EVENT_PATH)) {
85 const struct path *path = data;
86
87 if (d_unlinked(path->dentry))
88 return 0;
89 }
90 if (file_name) {
91 len = strlen(file_name);
92 alloc_len += len + 1;
93 }
94
95 pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
96 mask);
97
98 i_mark = container_of(inode_mark, struct inotify_inode_mark,
99 fsn_mark);
100
101 event = kmalloc(alloc_len, GFP_KERNEL);
102 if (unlikely(!event)) {
103 /*
104 * Treat lost event due to ENOMEM the same way as queue
105 * overflow to let userspace know event was lost.
106 */
107 fsnotify_queue_overflow(group);
108 return -ENOMEM;
109 }
110
111 fsn_event = &event->fse;
112 fsnotify_init_event(fsn_event, inode, mask);
113 event->wd = i_mark->wd;
114 event->sync_cookie = cookie;
115 event->name_len = len;
116 if (len)
117 strcpy(event->name, file_name);
118
119 ret = fsnotify_add_event(group, fsn_event, inotify_merge);
120 if (ret) {
121 /* Our event wasn't used in the end. Free it. */
122 fsnotify_destroy_event(group, fsn_event);
123 }
124
125 if (inode_mark->mask & IN_ONESHOT)
126 fsnotify_destroy_mark(inode_mark, group);
127
128 return 0;
129}
130
131static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
132{
133 inotify_ignored_and_remove_idr(fsn_mark, group);
134}
135
136/*
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.
142 */
143static int idr_callback(int id, void *p, void *data)
144{
145 struct fsnotify_mark *fsn_mark;
146 struct inotify_inode_mark *i_mark;
147 static bool warned = false;
148
149 if (warned)
150 return 0;
151
152 warned = true;
153 fsn_mark = p;
154 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
155
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);
158
159 /*
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.
164 */
165 if (fsn_mark)
166 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
167 fsn_mark->group, i_mark->wd);
168 return 0;
169}
170
171static void inotify_free_group_priv(struct fsnotify_group *group)
172{
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);
178}
179
180static void inotify_free_event(struct fsnotify_event *fsn_event)
181{
182 kfree(INOTIFY_E(fsn_event));
183}
184
185/* ding dong the mark is dead */
186static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
187{
188 struct inotify_inode_mark *i_mark;
189
190 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
191
192 kmem_cache_free(inotify_inode_mark_cachep, i_mark);
193}
194
195const struct fsnotify_ops inotify_fsnotify_ops = {
196 .handle_event = inotify_handle_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,
201};
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/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>
26
27#include "inotify.h"
28
29/*
30 * Check if 2 events contain the same information.
31 */
32static bool event_compare(struct fsnotify_event *old_fsn,
33 struct fsnotify_event *new_fsn)
34{
35 struct inotify_event_info *old, *new;
36
37 old = INOTIFY_E(old_fsn);
38 new = INOTIFY_E(new_fsn);
39 if (old->mask & FS_IN_IGNORED)
40 return false;
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)))
45 return true;
46 return false;
47}
48
49static int inotify_merge(struct list_head *list,
50 struct fsnotify_event *event)
51{
52 struct fsnotify_event *last_event;
53
54 last_event = list_entry(list->prev, struct fsnotify_event, list);
55 return event_compare(last_event, event);
56}
57
58static int inotify_one_event(struct fsnotify_group *group, u32 mask,
59 struct fsnotify_mark *inode_mark,
60 const struct path *path,
61 const struct qstr *file_name, u32 cookie)
62{
63 struct inotify_inode_mark *i_mark;
64 struct inotify_event_info *event;
65 struct fsnotify_event *fsn_event;
66 int ret;
67 int len = 0;
68 int alloc_len = sizeof(struct inotify_event_info);
69
70 if ((inode_mark->mask & FS_EXCL_UNLINK) &&
71 path && d_unlinked(path->dentry))
72 return 0;
73
74 if (file_name) {
75 len = file_name->len;
76 alloc_len += len + 1;
77 }
78
79 pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
80 mask);
81
82 i_mark = container_of(inode_mark, struct inotify_inode_mark,
83 fsn_mark);
84
85 /*
86 * Whoever is interested in the event, pays for the allocation. Do not
87 * trigger OOM killer in the target monitoring memcg as it may have
88 * security repercussion.
89 */
90 memalloc_use_memcg(group->memcg);
91 event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
92 memalloc_unuse_memcg();
93
94 if (unlikely(!event)) {
95 /*
96 * Treat lost event due to ENOMEM the same way as queue
97 * overflow to let userspace know event was lost.
98 */
99 fsnotify_queue_overflow(group);
100 return -ENOMEM;
101 }
102
103 /*
104 * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
105 * for fanotify. inotify never reported IN_ISDIR with those events.
106 * It looks like an oversight, but to avoid the risk of breaking
107 * existing inotify programs, mask the flag out from those events.
108 */
109 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
110 mask &= ~IN_ISDIR;
111
112 fsn_event = &event->fse;
113 fsnotify_init_event(fsn_event, 0);
114 event->mask = mask;
115 event->wd = i_mark->wd;
116 event->sync_cookie = cookie;
117 event->name_len = len;
118 if (len)
119 strcpy(event->name, file_name->name);
120
121 ret = fsnotify_add_event(group, fsn_event, inotify_merge);
122 if (ret) {
123 /* Our event wasn't used in the end. Free it. */
124 fsnotify_destroy_event(group, fsn_event);
125 }
126
127 if (inode_mark->mask & IN_ONESHOT)
128 fsnotify_destroy_mark(inode_mark, group);
129
130 return 0;
131}
132
133int inotify_handle_event(struct fsnotify_group *group, u32 mask,
134 const void *data, int data_type, struct inode *dir,
135 const struct qstr *file_name, u32 cookie,
136 struct fsnotify_iter_info *iter_info)
137{
138 const struct path *path = fsnotify_data_path(data, data_type);
139 struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
140 struct fsnotify_mark *child_mark = fsnotify_iter_child_mark(iter_info);
141 int ret = 0;
142
143 if (WARN_ON(fsnotify_iter_vfsmount_mark(iter_info)))
144 return 0;
145
146 /*
147 * Some events cannot be sent on both parent and child marks
148 * (e.g. IN_CREATE). Those events are always sent on inode_mark.
149 * For events that are possible on both parent and child (e.g. IN_OPEN),
150 * event is sent on inode_mark with name if the parent is watching and
151 * is sent on child_mark without name if child is watching.
152 * If both parent and child are watching, report the event with child's
153 * name here and report another event without child's name below.
154 */
155 if (inode_mark)
156 ret = inotify_one_event(group, mask, inode_mark, path,
157 file_name, cookie);
158 if (ret || !child_mark)
159 return ret;
160
161 return inotify_one_event(group, mask, child_mark, path, NULL, 0);
162}
163
164static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
165{
166 inotify_ignored_and_remove_idr(fsn_mark, group);
167}
168
169/*
170 * This is NEVER supposed to be called. Inotify marks should either have been
171 * removed from the idr when the watch was removed or in the
172 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
173 * torn down. This is only called if the idr is about to be freed but there
174 * are still marks in it.
175 */
176static int idr_callback(int id, void *p, void *data)
177{
178 struct fsnotify_mark *fsn_mark;
179 struct inotify_inode_mark *i_mark;
180 static bool warned = false;
181
182 if (warned)
183 return 0;
184
185 warned = true;
186 fsn_mark = p;
187 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
188
189 WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
190 "idr. Probably leaking memory\n", id, p, data);
191
192 /*
193 * I'm taking the liberty of assuming that the mark in question is a
194 * valid address and I'm dereferencing it. This might help to figure
195 * out why we got here and the panic is no worse than the original
196 * BUG() that was here.
197 */
198 if (fsn_mark)
199 printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
200 fsn_mark->group, i_mark->wd);
201 return 0;
202}
203
204static void inotify_free_group_priv(struct fsnotify_group *group)
205{
206 /* ideally the idr is empty and we won't hit the BUG in the callback */
207 idr_for_each(&group->inotify_data.idr, idr_callback, group);
208 idr_destroy(&group->inotify_data.idr);
209 if (group->inotify_data.ucounts)
210 dec_inotify_instances(group->inotify_data.ucounts);
211}
212
213static void inotify_free_event(struct fsnotify_event *fsn_event)
214{
215 kfree(INOTIFY_E(fsn_event));
216}
217
218/* ding dong the mark is dead */
219static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
220{
221 struct inotify_inode_mark *i_mark;
222
223 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
224
225 kmem_cache_free(inotify_inode_mark_cachep, i_mark);
226}
227
228const struct fsnotify_ops inotify_fsnotify_ops = {
229 .handle_event = inotify_handle_event,
230 .free_group_priv = inotify_free_group_priv,
231 .free_event = inotify_free_event,
232 .freeing_mark = inotify_freeing_mark,
233 .free_mark = inotify_free_mark,
234};