1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* audit_fsnotify.c -- tracking inodes
3 *
4 * Copyright 2003-2009,2014-2015 Red Hat, Inc.
5 * Copyright 2005 Hewlett-Packard Development Company, L.P.
6 * Copyright 2005 IBM Corporation
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/audit.h>
11 #include <linux/kthread.h>
12 #include <linux/mutex.h>
13 #include <linux/fs.h>
14 #include <linux/fsnotify_backend.h>
15 #include <linux/namei.h>
16 #include <linux/netlink.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <linux/security.h>
20 #include "audit.h"
21
22 /*
23 * this mark lives on the parent directory of the inode in question.
24 * but dev, ino, and path are about the child
25 */
26 struct audit_fsnotify_mark {
27 dev_t dev; /* associated superblock device */
28 unsigned long ino; /* associated inode number */
29 char *path; /* insertion path */
30 struct fsnotify_mark mark; /* fsnotify mark on the inode */
31 struct audit_krule *rule;
32 };
33
34 /* fsnotify handle. */
35 static struct fsnotify_group *audit_fsnotify_group;
36
37 /* fsnotify events we care about. */
38 #define AUDIT_FS_EVENTS (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
39 FS_MOVE_SELF)
40
41 static void audit_fsnotify_mark_free(struct audit_fsnotify_mark *audit_mark)
42 {
43 kfree(audit_mark->path);
44 kfree(audit_mark);
45 }
46
47 static void audit_fsnotify_free_mark(struct fsnotify_mark *mark)
48 {
49 struct audit_fsnotify_mark *audit_mark;
50
51 audit_mark = container_of(mark, struct audit_fsnotify_mark, mark);
52 audit_fsnotify_mark_free(audit_mark);
53 }
54
55 char *audit_mark_path(struct audit_fsnotify_mark *mark)
56 {
57 return mark->path;
58 }
59
60 int audit_mark_compare(struct audit_fsnotify_mark *mark, unsigned long ino, dev_t dev)
61 {
62 if (mark->ino == AUDIT_INO_UNSET)
63 return 0;
64 return (mark->ino == ino) && (mark->dev == dev);
65 }
66
67 static void audit_update_mark(struct audit_fsnotify_mark *audit_mark,
68 const struct inode *inode)
69 {
70 audit_mark->dev = inode ? inode->i_sb->s_dev : AUDIT_DEV_UNSET;
71 audit_mark->ino = inode ? inode->i_ino : AUDIT_INO_UNSET;
72 }
73
74 struct audit_fsnotify_mark *audit_alloc_mark(struct audit_krule *krule, char *pathname, int len)
75 {
76 struct audit_fsnotify_mark *audit_mark;
77 struct path path;
78 struct dentry *dentry;
79 struct inode *inode;
80 int ret;
81
82 if (pathname[0] != '/' || pathname[len-1] == '/')
83 return ERR_PTR(-EINVAL);
84
85 dentry = kern_path_locked(pathname, &path);
86 if (IS_ERR(dentry))
87 return ERR_CAST(dentry); /* returning an error */
88 inode = path.dentry->d_inode;
89 inode_unlock(inode);
90
91 audit_mark = kzalloc(sizeof(*audit_mark), GFP_KERNEL);
92 if (unlikely(!audit_mark)) {
93 audit_mark = ERR_PTR(-ENOMEM);
94 goto out;
95 }
96
97 fsnotify_init_mark(&audit_mark->mark, audit_fsnotify_group);
98 audit_mark->mark.mask = AUDIT_FS_EVENTS;
99 audit_mark->path = pathname;
100 audit_update_mark(audit_mark, dentry->d_inode);
101 audit_mark->rule = krule;
102
103 ret = fsnotify_add_inode_mark(&audit_mark->mark, inode, true);
104 if (ret < 0) {
105 fsnotify_put_mark(&audit_mark->mark);
106 audit_mark = ERR_PTR(ret);
107 }
108 out:
109 dput(dentry);
110 path_put(&path);
111 return audit_mark;
112 }
113
114 static void audit_mark_log_rule_change(struct audit_fsnotify_mark *audit_mark, char *op)
115 {
116 struct audit_buffer *ab;
117 struct audit_krule *rule = audit_mark->rule;
118
119 if (!audit_enabled)
120 return;
121 ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
122 if (unlikely(!ab))
123 return;
124 audit_log_session_info(ab);
125 audit_log_format(ab, " op=%s path=", op);
126 audit_log_untrustedstring(ab, audit_mark->path);
127 audit_log_key(ab, rule->filterkey);
128 audit_log_format(ab, " list=%d res=1", rule->listnr);
129 audit_log_end(ab);
130 }
131
132 void audit_remove_mark(struct audit_fsnotify_mark *audit_mark)
133 {
134 fsnotify_destroy_mark(&audit_mark->mark, audit_fsnotify_group);
135 fsnotify_put_mark(&audit_mark->mark);
136 }
137
138 void audit_remove_mark_rule(struct audit_krule *krule)
139 {
140 struct audit_fsnotify_mark *mark = krule->exe;
141
142 audit_remove_mark(mark);
143 }
144
145 static void audit_autoremove_mark_rule(struct audit_fsnotify_mark *audit_mark)
146 {
147 struct audit_krule *rule = audit_mark->rule;
148 struct audit_entry *entry = container_of(rule, struct audit_entry, rule);
149
150 audit_mark_log_rule_change(audit_mark, "autoremove_rule");
151 audit_del_rule(entry);
152 }
153
154 /* Update mark data in audit rules based on fsnotify events. */
155 static int audit_mark_handle_event(struct fsnotify_mark *inode_mark, u32 mask,
156 struct inode *inode, struct inode *dir,
157 const struct qstr *dname, u32 cookie)
158 {
159 struct audit_fsnotify_mark *audit_mark;
160
161 audit_mark = container_of(inode_mark, struct audit_fsnotify_mark, mark);
162
163 if (WARN_ON_ONCE(inode_mark->group != audit_fsnotify_group))
164 return 0;
165
166 if (mask & (FS_CREATE|FS_MOVED_TO|FS_DELETE|FS_MOVED_FROM)) {
167 if (audit_compare_dname_path(dname, audit_mark->path, AUDIT_NAME_FULL))
168 return 0;
169 audit_update_mark(audit_mark, inode);
170 } else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) {
171 audit_autoremove_mark_rule(audit_mark);
172 }
173
174 return 0;
175 }
176
177 static const struct fsnotify_ops audit_mark_fsnotify_ops = {
178 .handle_inode_event = audit_mark_handle_event,
179 .free_mark = audit_fsnotify_free_mark,
180 };
181
182 static int __init audit_fsnotify_init(void)
183 {
184 audit_fsnotify_group = fsnotify_alloc_group(&audit_mark_fsnotify_ops);
185 if (IS_ERR(audit_fsnotify_group)) {
186 audit_fsnotify_group = NULL;
187 audit_panic("cannot create audit fsnotify group");
188 }
189 return 0;
190 }
191 device_initcall(audit_fsnotify_init);
192
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