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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 fsnotify_group *group,
50 struct fsnotify_event *event)
51{
52 struct list_head *list = &group->notification_list;
53 struct fsnotify_event *last_event;
54
55 last_event = list_entry(list->prev, struct fsnotify_event, list);
56 return event_compare(last_event, event);
57}
58
59int 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)
62{
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;
67 int ret;
68 int len = 0;
69 int alloc_len = sizeof(struct inotify_event_info);
70 struct mem_cgroup *old_memcg;
71
72 if (name) {
73 len = name->len;
74 alloc_len += len + 1;
75 }
76
77 pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
78 mask);
79
80 i_mark = container_of(inode_mark, struct inotify_inode_mark,
81 fsn_mark);
82
83 /*
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.
87 */
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);
91
92 if (unlikely(!event)) {
93 /*
94 * Treat lost event due to ENOMEM the same way as queue
95 * overflow to let userspace know event was lost.
96 */
97 fsnotify_queue_overflow(group);
98 return -ENOMEM;
99 }
100
101 /*
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.
106 */
107 if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
108 mask &= ~IN_ISDIR;
109
110 fsn_event = &event->fse;
111 fsnotify_init_event(fsn_event);
112 event->mask = mask;
113 event->wd = i_mark->wd;
114 event->sync_cookie = cookie;
115 event->name_len = len;
116 if (len)
117 strcpy(event->name, name->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->flags & FSNOTIFY_MARK_FLAG_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_group *group,
181 struct fsnotify_event *fsn_event)
182{
183 kfree(INOTIFY_E(fsn_event));
184}
185
186/* ding dong the mark is dead */
187static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
188{
189 struct inotify_inode_mark *i_mark;
190
191 i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
192
193 kmem_cache_free(inotify_inode_mark_cachep, i_mark);
194}
195
196const struct fsnotify_ops inotify_fsnotify_ops = {
197 .handle_inode_event = inotify_handle_inode_event,
198 .free_group_priv = inotify_free_group_priv,
199 .free_event = inotify_free_event,
200 .freeing_mark = inotify_freeing_mark,
201 .free_mark = inotify_free_mark,
202};