1 /* audit_fsnotify.c -- tracking inodes
2 *
3 * Copyright 2003-2009,2014-2015 Red Hat, Inc.
4 * Copyright 2005 Hewlett-Packard Development Company, L.P.
5 * Copyright 2005 IBM Corporation
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 */
17
18 #include <linux/kernel.h>
19 #include <linux/audit.h>
20 #include <linux/kthread.h>
21 #include <linux/mutex.h>
22 #include <linux/fs.h>
23 #include <linux/fsnotify_backend.h>
24 #include <linux/namei.h>
25 #include <linux/netlink.h>
26 #include <linux/sched.h>
27 #include <linux/slab.h>
28 #include <linux/security.h>
29 #include "audit.h"
30
31 /*
32 * this mark lives on the parent directory of the inode in question.
33 * but dev, ino, and path are about the child
34 */
35 struct audit_fsnotify_mark {
36 dev_t dev; /* associated superblock device */
37 unsigned long ino; /* associated inode number */
38 char *path; /* insertion path */
39 struct fsnotify_mark mark; /* fsnotify mark on the inode */
40 struct audit_krule *rule;
41 };
42
43 /* fsnotify handle. */
44 static struct fsnotify_group *audit_fsnotify_group;
45
46 /* fsnotify events we care about. */
47 #define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
48 FS_MOVE_SELF | FS_EVENT_ON_CHILD)
49
50 static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
51 {
52 kfree(audit_mark->path);
53 kfree(audit_mark);
54 }
55
56 static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
57 {
58 struct audit_fsnotify_mark *audit_mark;
59
60 audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
61 audit_fsnotify_mark_free(audit_mark);
62 }
63
64 char *audit_mark_path(struct audit_fsnotify_mark *mark)
65 {
66 return mark->path;
67 }
68
69 int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
70 {
71 if (mark->ino == AUDIT_INO_UNSET)
72 return 0;
73 return (mark->ino == ino) && (mark->dev == dev);
74 }
75
76 static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
77 const struct inode *inode)
78 {
79 audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
80 audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
81 }
82
83 struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
84 {
85 struct audit_fsnotify_mark *audit_mark;
86 struct path path;
87 struct dentry *dentry;
88 struct inode *inode;
89 int ret;
90
91 if (pathname[0] != '/' || pathname[len-1] == '/')
92 return ERR_PTR(-EINVAL);
93
94 dentry = kern_path_locked(pathname, &path);
95 if (IS_ERR(dentry))
96 return (void *)dentry; /* returning an error */
97 inode = path.dentry->d_inode;
98 inode_unlock(inode);
99
100 audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
101 if (unlikely(!audit_mark)) {
102 audit_mark = ERR_PTR(-ENOMEM);
103 goto out;
104 }
105
106 fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
107 audit_mark->mark.mask = AUDIT_FS_EVENTS;
108 audit_mark->path = pathname;
109 audit_update_mark(audit_mark, dentry->d_inode);
110 audit_mark->rule = krule;
111
112 ret = fsnotify_add_mark(&audit_mark->mark, inode, NULL, true);
113 if (ret < 0) {
114 fsnotify_put_mark(&audit_mark->mark);
115 audit_mark = ERR_PTR(ret);
116 }
117 out:
118 dput(dentry);
119 path_put(&path);
120 return audit_mark;
121 }
122
123 static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
124 {
125 struct audit_buffer *ab;
126 struct audit_krule *rule = audit_mark->rule;
127
128 if (!audit_enabled)
129 return;
130 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
131 if (unlikely(!ab))
132 return;
133 audit_log_format(ab, "auid=%u ses=%u op=%s",
134 from_kuid(&init_user_ns, audit_get_loginuid(current)),
135 audit_get_sessionid(current), op);
136 audit_log_format(ab, " path=");
137 audit_log_untrustedstring(ab, audit_mark->path);
138 audit_log_key(ab, rule->filterkey);
139 audit_log_format(ab, " list=%d res=1", rule->listnr);
140 audit_log_end(ab);
141 }
142
143 void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
144 {
145 fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
146 fsnotify_put_mark(&audit_mark->mark);
147 }
148
149 void audit_remove_mark_rule(struct audit_krule *krule)
150 {
151 struct audit_fsnotify_mark *mark = krule->exe;
152
153 audit_remove_mark(mark);
154 }
155
156 static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
157 {
158 struct audit_krule *rule = audit_mark->rule;
159 struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
160
161 audit_mark_log_rule_change(audit_mark, "autoremove_rule");
162 audit_del_rule(entry);
163 }
164
165 /* Update mark data in audit rules based on fsnotify events. */
166 static int audit_mark_handle_event(struct fsnotify_group *group,
167 struct inode *to_tell,
168 struct fsnotify_mark *inode_mark,
169 struct fsnotify_mark *vfsmount_mark,
170 u32 mask, const void *data, int data_type,
171 const unsigned char *dname, u32 cookie,
172 struct fsnotify_iter_info *iter_info)
173 {
174 struct audit_fsnotify_mark *audit_mark;
175 const struct inode *inode = NULL;
176
177 audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
178
179 BUG_ON(group != audit_fsnotify_group);
180
181 switch (data_type) {
182 case (FSNOTIFY_EVENT_PATH):
183 inode = ((const struct path *)data)->dentry->d_inode;
184 break;
185 case (FSNOTIFY_EVENT_INODE):
186 inode = (const struct inode *)data;
187 break;
188 default:
189 BUG();
190 return 0;
191 }
192
193 if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
194 if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
195 return 0;
196 audit_update_mark(audit_mark, inode);
197 } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
198 audit_autoremove_mark_rule(audit_mark);
199
200 return 0;
201 }
202
203 static const struct fsnotify_ops audit_mark_fsnotify_ops = {
204 .handle_event = audit_mark_handle_event,
205 .free_mark = audit_fsnotify_free_mark,
206 };
207
208 static int __init audit_fsnotify_init(void)
209 {
210 audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
211 if (IS_ERR(audit_fsnotify_group)) {
212 audit_fsnotify_group = NULL;
213 audit_panic("cannot create audit fsnotify group");
214 }
215 return 0;
216 }
217 device_initcall(audit_fsnotify_init);
218
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