Line data Source code
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 : */
32 0 : static bool event_compare(struct fsnotify_event *old_fsn,
33 : struct fsnotify_event *new_fsn)
34 : {
35 : struct inotify_event_info *old, *new;
36 :
37 0 : old = INOTIFY_E(old_fsn);
38 0 : new = INOTIFY_E(new_fsn);
39 0 : if (old->mask & FS_IN_IGNORED)
40 : return false;
41 0 : if ((old->mask == new->mask) &&
42 0 : (old->wd == new->wd) &&
43 0 : (old->name_len == new->name_len) &&
44 0 : (!old->name_len || !strcmp(old->name, new->name)))
45 : return true;
46 : return false;
47 : }
48 :
49 0 : static int inotify_merge(struct fsnotify_group *group,
50 : struct fsnotify_event *event)
51 : {
52 0 : struct list_head *list = &group->notification_list;
53 : struct fsnotify_event *last_event;
54 :
55 0 : last_event = list_entry(list->prev, struct fsnotify_event, list);
56 0 : return event_compare(last_event, event);
57 : }
58 :
59 0 : 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)
62 : {
63 : struct inotify_inode_mark *i_mark;
64 : struct inotify_event_info *event;
65 : struct fsnotify_event *fsn_event;
66 0 : struct fsnotify_group *group = inode_mark->group;
67 : int ret;
68 0 : int len = 0, wd;
69 0 : int alloc_len = sizeof(struct inotify_event_info);
70 : struct mem_cgroup *old_memcg;
71 :
72 0 : if (name) {
73 0 : len = name->len;
74 0 : 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 0 : i_mark = container_of(inode_mark, struct inotify_inode_mark,
81 : fsn_mark);
82 :
83 : /*
84 : * We can be racing with mark being detached. Don't report event with
85 : * invalid wd.
86 : */
87 0 : wd = READ_ONCE(i_mark->wd);
88 0 : if (wd == -1)
89 : return 0;
90 : /*
91 : * Whoever is interested in the event, pays for the allocation. Do not
92 : * trigger OOM killer in the target monitoring memcg as it may have
93 : * security repercussion.
94 : */
95 0 : old_memcg = set_active_memcg(group->memcg);
96 0 : event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
97 : set_active_memcg(old_memcg);
98 :
99 0 : if (unlikely(!event)) {
100 : /*
101 : * Treat lost event due to ENOMEM the same way as queue
102 : * overflow to let userspace know event was lost.
103 : */
104 0 : fsnotify_queue_overflow(group);
105 0 : return -ENOMEM;
106 : }
107 :
108 : /*
109 : * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
110 : * for fanotify. inotify never reported IN_ISDIR with those events.
111 : * It looks like an oversight, but to avoid the risk of breaking
112 : * existing inotify programs, mask the flag out from those events.
113 : */
114 0 : if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
115 0 : mask &= ~IN_ISDIR;
116 :
117 0 : fsn_event = &event->fse;
118 0 : fsnotify_init_event(fsn_event);
119 0 : event->mask = mask;
120 0 : event->wd = wd;
121 0 : event->sync_cookie = cookie;
122 0 : event->name_len = len;
123 0 : if (len)
124 0 : strcpy(event->name, name->name);
125 :
126 0 : ret = fsnotify_add_event(group, fsn_event, inotify_merge);
127 0 : if (ret) {
128 : /* Our event wasn't used in the end. Free it. */
129 0 : fsnotify_destroy_event(group, fsn_event);
130 : }
131 :
132 0 : if (inode_mark->flags & FSNOTIFY_MARK_FLAG_IN_ONESHOT)
133 0 : fsnotify_destroy_mark(inode_mark, group);
134 :
135 : return 0;
136 : }
137 :
138 0 : static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
139 : {
140 0 : inotify_ignored_and_remove_idr(fsn_mark, group);
141 0 : }
142 :
143 : /*
144 : * This is NEVER supposed to be called. Inotify marks should either have been
145 : * removed from the idr when the watch was removed or in the
146 : * fsnotify_destroy_mark_by_group() call when the inotify instance was being
147 : * torn down. This is only called if the idr is about to be freed but there
148 : * are still marks in it.
149 : */
150 0 : static int idr_callback(int id, void *p, void *data)
151 : {
152 : struct fsnotify_mark *fsn_mark;
153 : struct inotify_inode_mark *i_mark;
154 : static bool warned = false;
155 :
156 0 : if (warned)
157 : return 0;
158 :
159 0 : warned = true;
160 0 : fsn_mark = p;
161 0 : i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
162 :
163 0 : WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
164 : "idr. Probably leaking memory\n", id, p, data);
165 :
166 : /*
167 : * I'm taking the liberty of assuming that the mark in question is a
168 : * valid address and I'm dereferencing it. This might help to figure
169 : * out why we got here and the panic is no worse than the original
170 : * BUG() that was here.
171 : */
172 0 : if (fsn_mark)
173 0 : printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
174 : fsn_mark->group, i_mark->wd);
175 : return 0;
176 : }
177 :
178 0 : static void inotify_free_group_priv(struct fsnotify_group *group)
179 : {
180 : /* ideally the idr is empty and we won't hit the BUG in the callback */
181 0 : idr_for_each(&group->inotify_data.idr, idr_callback, group);
182 0 : idr_destroy(&group->inotify_data.idr);
183 0 : if (group->inotify_data.ucounts)
184 0 : dec_inotify_instances(group->inotify_data.ucounts);
185 0 : }
186 :
187 0 : static void inotify_free_event(struct fsnotify_group *group,
188 : struct fsnotify_event *fsn_event)
189 : {
190 0 : kfree(INOTIFY_E(fsn_event));
191 0 : }
192 :
193 : /* ding dong the mark is dead */
194 0 : static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
195 : {
196 : struct inotify_inode_mark *i_mark;
197 :
198 0 : i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
199 :
200 0 : kmem_cache_free(inotify_inode_mark_cachep, i_mark);
201 0 : }
202 :
203 : const struct fsnotify_ops inotify_fsnotify_ops = {
204 : .handle_inode_event = inotify_handle_inode_event,
205 : .free_group_priv = inotify_free_group_priv,
206 : .free_event = inotify_free_event,
207 : .freeing_mark = inotify_freeing_mark,
208 : .free_mark = inotify_free_mark,
209 : };
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