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Greg KHb67dbf92005-07-07 14:37:53 -07001/*
2 * inode.c - securityfs
3 *
4 * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version
8 * 2 as published by the Free Software Foundation.
9 *
10 * Based on fs/debugfs/inode.c which had the following copyright notice:
11 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
12 * Copyright (C) 2004 IBM Inc.
13 */
14
15/* #define DEBUG */
Greg KHb67dbf92005-07-07 14:37:53 -070016#include <linux/module.h>
17#include <linux/fs.h>
18#include <linux/mount.h>
19#include <linux/pagemap.h>
20#include <linux/init.h>
21#include <linux/namei.h>
22#include <linux/security.h>
Mimi Zohar92562922008-10-07 14:00:12 -040023#include <linux/magic.h>
Greg KHb67dbf92005-07-07 14:37:53 -070024
25static struct vfsmount *mount;
26static int mount_count;
27
28/*
29 * TODO:
30 * I think I can get rid of these default_file_ops, but not quite sure...
31 */
32static ssize_t default_read_file(struct file *file, char __user *buf,
33 size_t count, loff_t *ppos)
34{
35 return 0;
36}
37
38static ssize_t default_write_file(struct file *file, const char __user *buf,
39 size_t count, loff_t *ppos)
40{
41 return count;
42}
43
44static int default_open(struct inode *inode, struct file *file)
45{
Theodore Ts'o8e18e292006-09-27 01:50:46 -070046 if (inode->i_private)
47 file->private_data = inode->i_private;
Greg KHb67dbf92005-07-07 14:37:53 -070048
49 return 0;
50}
51
Arjan van de Ven9c2e08c2007-02-12 00:55:37 -080052static const struct file_operations default_file_ops = {
Greg KHb67dbf92005-07-07 14:37:53 -070053 .read = default_read_file,
54 .write = default_write_file,
55 .open = default_open,
56};
57
58static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
59{
60 struct inode *inode = new_inode(sb);
61
62 if (inode) {
63 inode->i_mode = mode;
Greg KHb67dbf92005-07-07 14:37:53 -070064 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
65 switch (mode & S_IFMT) {
66 default:
67 init_special_inode(inode, mode, dev);
68 break;
69 case S_IFREG:
70 inode->i_fop = &default_file_ops;
71 break;
72 case S_IFDIR:
73 inode->i_op = &simple_dir_inode_operations;
74 inode->i_fop = &simple_dir_operations;
75
76 /* directory inodes start off with i_nlink == 2 (for "." entry) */
Dave Hansend8c76e62006-09-30 23:29:04 -070077 inc_nlink(inode);
Greg KHb67dbf92005-07-07 14:37:53 -070078 break;
79 }
80 }
81 return inode;
82}
83
84/* SMP-safe */
85static int mknod(struct inode *dir, struct dentry *dentry,
86 int mode, dev_t dev)
87{
88 struct inode *inode;
89 int error = -EPERM;
90
91 if (dentry->d_inode)
92 return -EEXIST;
93
94 inode = get_inode(dir->i_sb, mode, dev);
95 if (inode) {
96 d_instantiate(dentry, inode);
97 dget(dentry);
98 error = 0;
99 }
100 return error;
101}
102
103static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
104{
105 int res;
106
107 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
108 res = mknod(dir, dentry, mode, 0);
109 if (!res)
Dave Hansend8c76e62006-09-30 23:29:04 -0700110 inc_nlink(dir);
Greg KHb67dbf92005-07-07 14:37:53 -0700111 return res;
112}
113
114static int create(struct inode *dir, struct dentry *dentry, int mode)
115{
116 mode = (mode & S_IALLUGO) | S_IFREG;
117 return mknod(dir, dentry, mode, 0);
118}
119
120static inline int positive(struct dentry *dentry)
121{
122 return dentry->d_inode && !d_unhashed(dentry);
123}
124
125static int fill_super(struct super_block *sb, void *data, int silent)
126{
127 static struct tree_descr files[] = {{""}};
128
129 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
130}
131
David Howells454e2392006-06-23 02:02:57 -0700132static int get_sb(struct file_system_type *fs_type,
133 int flags, const char *dev_name,
134 void *data, struct vfsmount *mnt)
Greg KHb67dbf92005-07-07 14:37:53 -0700135{
David Howells454e2392006-06-23 02:02:57 -0700136 return get_sb_single(fs_type, flags, data, fill_super, mnt);
Greg KHb67dbf92005-07-07 14:37:53 -0700137}
138
139static struct file_system_type fs_type = {
140 .owner = THIS_MODULE,
141 .name = "securityfs",
142 .get_sb = get_sb,
143 .kill_sb = kill_litter_super,
144};
145
146static int create_by_name(const char *name, mode_t mode,
147 struct dentry *parent,
148 struct dentry **dentry)
149{
150 int error = 0;
151
152 *dentry = NULL;
153
154 /* If the parent is not specified, we create it in the root.
155 * We need the root dentry to do this, which is in the super
156 * block. A pointer to that is in the struct vfsmount that we
157 * have around.
158 */
Al Viroef52c752010-01-25 04:50:43 -0500159 if (!parent)
160 parent = mount->mnt_sb->s_root;
Greg KHb67dbf92005-07-07 14:37:53 -0700161
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800162 mutex_lock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700163 *dentry = lookup_one_len(name, parent, strlen(name));
164 if (!IS_ERR(dentry)) {
165 if ((mode & S_IFMT) == S_IFDIR)
166 error = mkdir(parent->d_inode, *dentry, mode);
167 else
168 error = create(parent->d_inode, *dentry, mode);
169 } else
170 error = PTR_ERR(dentry);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800171 mutex_unlock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700172
173 return error;
174}
175
176/**
177 * securityfs_create_file - create a file in the securityfs filesystem
178 *
179 * @name: a pointer to a string containing the name of the file to create.
180 * @mode: the permission that the file should have
181 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700182 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700183 * file will be created in the root of the securityfs filesystem.
184 * @data: a pointer to something that the caller will want to get to later
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700185 * on. The inode.i_private pointer will point to this value on
Greg KHb67dbf92005-07-07 14:37:53 -0700186 * the open() call.
187 * @fops: a pointer to a struct file_operations that should be used for
188 * this file.
189 *
190 * This is the basic "create a file" function for securityfs. It allows for a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700191 * wide range of flexibility in creating a file, or a directory (if you
Greg KHb67dbf92005-07-07 14:37:53 -0700192 * want to create a directory, the securityfs_create_dir() function is
Randy Dunlap3f23d812008-08-17 21:44:22 -0700193 * recommended to be used instead).
Greg KHb67dbf92005-07-07 14:37:53 -0700194 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700195 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700196 * pointer must be passed to the securityfs_remove() function when the file is
197 * to be removed (no automatic cleanup happens if your module is unloaded,
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -0800198 * you are responsible here). If an error occurs, the function will return
199 * the erorr value (via ERR_PTR).
Greg KHb67dbf92005-07-07 14:37:53 -0700200 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700201 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -0800202 * returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700203 */
204struct dentry *securityfs_create_file(const char *name, mode_t mode,
205 struct dentry *parent, void *data,
Arjan van de Ven9c2e08c2007-02-12 00:55:37 -0800206 const struct file_operations *fops)
Greg KHb67dbf92005-07-07 14:37:53 -0700207{
208 struct dentry *dentry = NULL;
209 int error;
210
211 pr_debug("securityfs: creating file '%s'\n",name);
212
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400213 error = simple_pin_fs(&fs_type, &mount, &mount_count);
Greg KHb67dbf92005-07-07 14:37:53 -0700214 if (error) {
215 dentry = ERR_PTR(error);
216 goto exit;
217 }
218
219 error = create_by_name(name, mode, parent, &dentry);
220 if (error) {
221 dentry = ERR_PTR(error);
222 simple_release_fs(&mount, &mount_count);
223 goto exit;
224 }
225
226 if (dentry->d_inode) {
227 if (fops)
228 dentry->d_inode->i_fop = fops;
229 if (data)
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700230 dentry->d_inode->i_private = data;
Greg KHb67dbf92005-07-07 14:37:53 -0700231 }
232exit:
233 return dentry;
234}
235EXPORT_SYMBOL_GPL(securityfs_create_file);
236
237/**
238 * securityfs_create_dir - create a directory in the securityfs filesystem
239 *
240 * @name: a pointer to a string containing the name of the directory to
241 * create.
242 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700243 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700244 * directory will be created in the root of the securityfs filesystem.
245 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700246 * This function creates a directory in securityfs with the given @name.
Greg KHb67dbf92005-07-07 14:37:53 -0700247 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700248 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700249 * pointer must be passed to the securityfs_remove() function when the file is
250 * to be removed (no automatic cleanup happens if your module is unloaded,
Randy Dunlap3f23d812008-08-17 21:44:22 -0700251 * you are responsible here). If an error occurs, %NULL will be returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700252 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700253 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Greg KHb67dbf92005-07-07 14:37:53 -0700254 * returned. It is not wise to check for this value, but rather, check for
Randy Dunlap3f23d812008-08-17 21:44:22 -0700255 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
Greg KHb67dbf92005-07-07 14:37:53 -0700256 * code.
257 */
258struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
259{
260 return securityfs_create_file(name,
261 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
262 parent, NULL, NULL);
263}
264EXPORT_SYMBOL_GPL(securityfs_create_dir);
265
266/**
267 * securityfs_remove - removes a file or directory from the securityfs filesystem
268 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700269 * @dentry: a pointer to a the dentry of the file or directory to be removed.
Greg KHb67dbf92005-07-07 14:37:53 -0700270 *
271 * This function removes a file or directory in securityfs that was previously
272 * created with a call to another securityfs function (like
273 * securityfs_create_file() or variants thereof.)
274 *
275 * This function is required to be called in order for the file to be
Randy Dunlap3f23d812008-08-17 21:44:22 -0700276 * removed. No automatic cleanup of files will happen when a module is
277 * removed; you are responsible here.
Greg KHb67dbf92005-07-07 14:37:53 -0700278 */
279void securityfs_remove(struct dentry *dentry)
280{
281 struct dentry *parent;
282
Eric Parisd93e4c92009-05-11 20:47:15 -0400283 if (!dentry || IS_ERR(dentry))
Greg KHb67dbf92005-07-07 14:37:53 -0700284 return;
285
286 parent = dentry->d_parent;
287 if (!parent || !parent->d_inode)
288 return;
289
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800290 mutex_lock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700291 if (positive(dentry)) {
292 if (dentry->d_inode) {
293 if (S_ISDIR(dentry->d_inode->i_mode))
294 simple_rmdir(parent->d_inode, dentry);
295 else
296 simple_unlink(parent->d_inode, dentry);
297 dput(dentry);
298 }
299 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800300 mutex_unlock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700301 simple_release_fs(&mount, &mount_count);
302}
303EXPORT_SYMBOL_GPL(securityfs_remove);
304
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100305static struct kobject *security_kobj;
Greg KHb67dbf92005-07-07 14:37:53 -0700306
307static int __init securityfs_init(void)
308{
309 int retval;
310
Greg Kroah-Hartman0ff21e42007-11-06 10:36:58 -0800311 security_kobj = kobject_create_and_add("security", kernel_kobj);
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100312 if (!security_kobj)
313 return -EINVAL;
Greg KHb67dbf92005-07-07 14:37:53 -0700314
315 retval = register_filesystem(&fs_type);
316 if (retval)
Greg Kroah-Hartman78a2d902007-12-20 08:13:05 -0800317 kobject_put(security_kobj);
Greg KHb67dbf92005-07-07 14:37:53 -0700318 return retval;
319}
320
Greg KHb67dbf92005-07-07 14:37:53 -0700321core_initcall(securityfs_init);
Greg KHb67dbf92005-07-07 14:37:53 -0700322MODULE_LICENSE("GPL");
323