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 74 : static bool event_compare(struct fsnotify_event *old_fsn,
33 : struct fsnotify_event *new_fsn)
34 : {
35 74 : struct inotify_event_info *old, *new;
36 :
37 74 : old = INOTIFY_E(old_fsn);
38 74 : new = INOTIFY_E(new_fsn);
39 74 : if (old->mask & FS_IN_IGNORED)
40 : return false;
41 71 : if ((old->mask == new->mask) &&
42 5 : (old->wd == new->wd) &&
43 5 : (old->name_len == new->name_len) &&
44 0 : (!old->name_len || !strcmp(old->name, new->name)))
45 5 : return true;
46 : return false;
47 : }
48 :
49 74 : static int inotify_merge(struct list_head *list,
50 : struct fsnotify_event *event)
51 : {
52 74 : struct fsnotify_event *last_event;
53 :
54 74 : last_event = list_entry(list->prev, struct fsnotify_event, list);
55 74 : return event_compare(last_event, event);
56 : }
57 :
58 144 : int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
59 : struct inode *inode, struct inode *dir,
60 : const struct qstr *name, u32 cookie)
61 : {
62 144 : struct inotify_inode_mark *i_mark;
63 144 : struct inotify_event_info *event;
64 144 : struct fsnotify_event *fsn_event;
65 144 : struct fsnotify_group *group = inode_mark->group;
66 144 : int ret;
67 144 : int len = 0;
68 144 : int alloc_len = sizeof(struct inotify_event_info);
69 144 : struct mem_cgroup *old_memcg;
70 :
71 144 : if (name) {
72 9 : len = name->len;
73 9 : alloc_len += len + 1;
74 : }
75 :
76 144 : pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
77 : mask);
78 :
79 144 : i_mark = container_of(inode_mark, struct inotify_inode_mark,
80 : fsn_mark);
81 :
82 : /*
83 : * Whoever is interested in the event, pays for the allocation. Do not
84 : * trigger OOM killer in the target monitoring memcg as it may have
85 : * security repercussion.
86 : */
87 144 : old_memcg = set_active_memcg(group->memcg);
88 144 : event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
89 144 : set_active_memcg(old_memcg);
90 :
91 144 : if (unlikely(!event)) {
92 : /*
93 : * Treat lost event due to ENOMEM the same way as queue
94 : * overflow to let userspace know event was lost.
95 : */
96 0 : fsnotify_queue_overflow(group);
97 0 : return -ENOMEM;
98 : }
99 :
100 : /*
101 : * We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
102 : * for fanotify. inotify never reported IN_ISDIR with those events.
103 : * It looks like an oversight, but to avoid the risk of breaking
104 : * existing inotify programs, mask the flag out from those events.
105 : */
106 144 : if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
107 0 : mask &= ~IN_ISDIR;
108 :
109 144 : fsn_event = &event->fse;
110 144 : fsnotify_init_event(fsn_event, 0);
111 144 : event->mask = mask;
112 144 : event->wd = i_mark->wd;
113 144 : event->sync_cookie = cookie;
114 144 : event->name_len = len;
115 144 : if (len)
116 9 : strcpy(event->name, name->name);
117 :
118 144 : ret = fsnotify_add_event(group, fsn_event, inotify_merge);
119 144 : if (ret) {
120 : /* Our event wasn't used in the end. Free it. */
121 11 : fsnotify_destroy_event(group, fsn_event);
122 : }
123 :
124 144 : if (inode_mark->mask & IN_ONESHOT)
125 0 : fsnotify_destroy_mark(inode_mark, group);
126 :
127 : return 0;
128 : }
129 :
130 37 : static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
131 : {
132 37 : inotify_ignored_and_remove_idr(fsn_mark, group);
133 37 : }
134 :
135 : /*
136 : * This is NEVER supposed to be called. Inotify marks should either have been
137 : * removed from the idr when the watch was removed or in the
138 : * fsnotify_destroy_mark_by_group() call when the inotify instance was being
139 : * torn down. This is only called if the idr is about to be freed but there
140 : * are still marks in it.
141 : */
142 0 : static int idr_callback(int id, void *p, void *data)
143 : {
144 0 : struct fsnotify_mark *fsn_mark;
145 0 : struct inotify_inode_mark *i_mark;
146 0 : static bool warned = false;
147 :
148 0 : if (warned)
149 : return 0;
150 :
151 0 : warned = true;
152 0 : fsn_mark = p;
153 0 : i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
154 :
155 0 : WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
156 : "idr. Probably leaking memory\n", id, p, data);
157 :
158 : /*
159 : * I'm taking the liberty of assuming that the mark in question is a
160 : * valid address and I'm dereferencing it. This might help to figure
161 : * out why we got here and the panic is no worse than the original
162 : * BUG() that was here.
163 : */
164 0 : if (fsn_mark)
165 0 : printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
166 : fsn_mark->group, i_mark->wd);
167 : return 0;
168 : }
169 :
170 7 : static void inotify_free_group_priv(struct fsnotify_group *group)
171 : {
172 : /* ideally the idr is empty and we won't hit the BUG in the callback */
173 7 : idr_for_each(&group->inotify_data.idr, idr_callback, group);
174 7 : idr_destroy(&group->inotify_data.idr);
175 7 : if (group->inotify_data.ucounts)
176 7 : dec_inotify_instances(group->inotify_data.ucounts);
177 7 : }
178 :
179 151 : static void inotify_free_event(struct fsnotify_event *fsn_event)
180 : {
181 151 : kfree(INOTIFY_E(fsn_event));
182 151 : }
183 :
184 : /* ding dong the mark is dead */
185 37 : static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
186 : {
187 37 : struct inotify_inode_mark *i_mark;
188 :
189 37 : i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
190 :
191 37 : kmem_cache_free(inotify_inode_mark_cachep, i_mark);
192 37 : }
193 :
194 : const struct fsnotify_ops inotify_fsnotify_ops = {
195 : .handle_inode_event = inotify_handle_inode_event,
196 : .free_group_priv = inotify_free_group_priv,
197 : .free_event = inotify_free_event,
198 : .freeing_mark = inotify_freeing_mark,
199 : .free_mark = inotify_free_mark,
200 : };
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