blob: cb8f47c66a58bb7eb11c0a75319f378261393f14 [file] [log] [blame]
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,
Arnd Bergmann6038f372010-08-15 18:52:59 +020056 .llseek = noop_llseek,
Greg KHb67dbf92005-07-07 14:37:53 -070057};
58
59static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
60{
61 struct inode *inode = new_inode(sb);
62
63 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -040064 inode->i_ino = get_next_ino();
Greg KHb67dbf92005-07-07 14:37:53 -070065 inode->i_mode = mode;
Greg KHb67dbf92005-07-07 14:37:53 -070066 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
67 switch (mode & S_IFMT) {
68 default:
69 init_special_inode(inode, mode, dev);
70 break;
71 case S_IFREG:
72 inode->i_fop = &default_file_ops;
73 break;
74 case S_IFDIR:
75 inode->i_op = &simple_dir_inode_operations;
76 inode->i_fop = &simple_dir_operations;
77
78 /* directory inodes start off with i_nlink == 2 (for "." entry) */
Dave Hansend8c76e62006-09-30 23:29:04 -070079 inc_nlink(inode);
Greg KHb67dbf92005-07-07 14:37:53 -070080 break;
81 }
82 }
83 return inode;
84}
85
86/* SMP-safe */
87static int mknod(struct inode *dir, struct dentry *dentry,
88 int mode, dev_t dev)
89{
90 struct inode *inode;
Tvrtko Ursulinb8bc83a2010-07-15 13:25:06 +010091 int error = -ENOMEM;
Greg KHb67dbf92005-07-07 14:37:53 -070092
93 if (dentry->d_inode)
94 return -EEXIST;
95
96 inode = get_inode(dir->i_sb, mode, dev);
97 if (inode) {
98 d_instantiate(dentry, inode);
99 dget(dentry);
100 error = 0;
101 }
102 return error;
103}
104
105static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
106{
107 int res;
108
109 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
110 res = mknod(dir, dentry, mode, 0);
111 if (!res)
Dave Hansend8c76e62006-09-30 23:29:04 -0700112 inc_nlink(dir);
Greg KHb67dbf92005-07-07 14:37:53 -0700113 return res;
114}
115
116static int create(struct inode *dir, struct dentry *dentry, int mode)
117{
118 mode = (mode & S_IALLUGO) | S_IFREG;
119 return mknod(dir, dentry, mode, 0);
120}
121
122static inline int positive(struct dentry *dentry)
123{
124 return dentry->d_inode && !d_unhashed(dentry);
125}
126
127static int fill_super(struct super_block *sb, void *data, int silent)
128{
129 static struct tree_descr files[] = {{""}};
130
131 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
132}
133
David Howells454e2392006-06-23 02:02:57 -0700134static int get_sb(struct file_system_type *fs_type,
135 int flags, const char *dev_name,
136 void *data, struct vfsmount *mnt)
Greg KHb67dbf92005-07-07 14:37:53 -0700137{
David Howells454e2392006-06-23 02:02:57 -0700138 return get_sb_single(fs_type, flags, data, fill_super, mnt);
Greg KHb67dbf92005-07-07 14:37:53 -0700139}
140
141static struct file_system_type fs_type = {
142 .owner = THIS_MODULE,
143 .name = "securityfs",
144 .get_sb = get_sb,
145 .kill_sb = kill_litter_super,
146};
147
148static int create_by_name(const char *name, mode_t mode,
149 struct dentry *parent,
150 struct dentry **dentry)
151{
152 int error = 0;
153
154 *dentry = NULL;
155
156 /* If the parent is not specified, we create it in the root.
157 * We need the root dentry to do this, which is in the super
158 * block. A pointer to that is in the struct vfsmount that we
159 * have around.
160 */
Al Viroef52c752010-01-25 04:50:43 -0500161 if (!parent)
162 parent = mount->mnt_sb->s_root;
Greg KHb67dbf92005-07-07 14:37:53 -0700163
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800164 mutex_lock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700165 *dentry = lookup_one_len(name, parent, strlen(name));
Dan Carpenterb338cc82010-04-22 12:05:35 +0200166 if (!IS_ERR(*dentry)) {
Greg KHb67dbf92005-07-07 14:37:53 -0700167 if ((mode & S_IFMT) == S_IFDIR)
168 error = mkdir(parent->d_inode, *dentry, mode);
169 else
170 error = create(parent->d_inode, *dentry, mode);
Tvrtko Ursulinb8bc83a2010-07-15 13:25:06 +0100171 if (error)
172 dput(*dentry);
Greg KHb67dbf92005-07-07 14:37:53 -0700173 } else
Dan Carpenterb338cc82010-04-22 12:05:35 +0200174 error = PTR_ERR(*dentry);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800175 mutex_unlock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700176
177 return error;
178}
179
180/**
181 * securityfs_create_file - create a file in the securityfs filesystem
182 *
183 * @name: a pointer to a string containing the name of the file to create.
184 * @mode: the permission that the file should have
185 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700186 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700187 * file will be created in the root of the securityfs filesystem.
188 * @data: a pointer to something that the caller will want to get to later
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700189 * on. The inode.i_private pointer will point to this value on
Greg KHb67dbf92005-07-07 14:37:53 -0700190 * the open() call.
191 * @fops: a pointer to a struct file_operations that should be used for
192 * this file.
193 *
194 * This is the basic "create a file" function for securityfs. It allows for a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700195 * wide range of flexibility in creating a file, or a directory (if you
Greg KHb67dbf92005-07-07 14:37:53 -0700196 * want to create a directory, the securityfs_create_dir() function is
Randy Dunlap3f23d812008-08-17 21:44:22 -0700197 * recommended to be used instead).
Greg KHb67dbf92005-07-07 14:37:53 -0700198 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700199 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700200 * pointer must be passed to the securityfs_remove() function when the file is
201 * to be removed (no automatic cleanup happens if your module is unloaded,
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -0800202 * you are responsible here). If an error occurs, the function will return
203 * the erorr value (via ERR_PTR).
Greg KHb67dbf92005-07-07 14:37:53 -0700204 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700205 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -0800206 * returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700207 */
208struct dentry *securityfs_create_file(const char *name, mode_t mode,
209 struct dentry *parent, void *data,
Arjan van de Ven9c2e08c2007-02-12 00:55:37 -0800210 const struct file_operations *fops)
Greg KHb67dbf92005-07-07 14:37:53 -0700211{
212 struct dentry *dentry = NULL;
213 int error;
214
215 pr_debug("securityfs: creating file '%s'\n",name);
216
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -0400217 error = simple_pin_fs(&fs_type, &mount, &mount_count);
Greg KHb67dbf92005-07-07 14:37:53 -0700218 if (error) {
219 dentry = ERR_PTR(error);
220 goto exit;
221 }
222
223 error = create_by_name(name, mode, parent, &dentry);
224 if (error) {
225 dentry = ERR_PTR(error);
226 simple_release_fs(&mount, &mount_count);
227 goto exit;
228 }
229
230 if (dentry->d_inode) {
231 if (fops)
232 dentry->d_inode->i_fop = fops;
233 if (data)
Theodore Ts'o8e18e292006-09-27 01:50:46 -0700234 dentry->d_inode->i_private = data;
Greg KHb67dbf92005-07-07 14:37:53 -0700235 }
236exit:
237 return dentry;
238}
239EXPORT_SYMBOL_GPL(securityfs_create_file);
240
241/**
242 * securityfs_create_dir - create a directory in the securityfs filesystem
243 *
244 * @name: a pointer to a string containing the name of the directory to
245 * create.
246 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700247 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700248 * directory will be created in the root of the securityfs filesystem.
249 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700250 * This function creates a directory in securityfs with the given @name.
Greg KHb67dbf92005-07-07 14:37:53 -0700251 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700252 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700253 * pointer must be passed to the securityfs_remove() function when the file is
254 * to be removed (no automatic cleanup happens if your module is unloaded,
Randy Dunlap3f23d812008-08-17 21:44:22 -0700255 * you are responsible here). If an error occurs, %NULL will be returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700256 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700257 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Greg KHb67dbf92005-07-07 14:37:53 -0700258 * returned. It is not wise to check for this value, but rather, check for
Randy Dunlap3f23d812008-08-17 21:44:22 -0700259 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
Greg KHb67dbf92005-07-07 14:37:53 -0700260 * code.
261 */
262struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
263{
264 return securityfs_create_file(name,
265 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
266 parent, NULL, NULL);
267}
268EXPORT_SYMBOL_GPL(securityfs_create_dir);
269
270/**
271 * securityfs_remove - removes a file or directory from the securityfs filesystem
272 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700273 * @dentry: a pointer to a the dentry of the file or directory to be removed.
Greg KHb67dbf92005-07-07 14:37:53 -0700274 *
275 * This function removes a file or directory in securityfs that was previously
276 * created with a call to another securityfs function (like
277 * securityfs_create_file() or variants thereof.)
278 *
279 * This function is required to be called in order for the file to be
Randy Dunlap3f23d812008-08-17 21:44:22 -0700280 * removed. No automatic cleanup of files will happen when a module is
281 * removed; you are responsible here.
Greg KHb67dbf92005-07-07 14:37:53 -0700282 */
283void securityfs_remove(struct dentry *dentry)
284{
285 struct dentry *parent;
286
Eric Parisd93e4c92009-05-11 20:47:15 -0400287 if (!dentry || IS_ERR(dentry))
Greg KHb67dbf92005-07-07 14:37:53 -0700288 return;
289
290 parent = dentry->d_parent;
291 if (!parent || !parent->d_inode)
292 return;
293
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800294 mutex_lock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700295 if (positive(dentry)) {
296 if (dentry->d_inode) {
297 if (S_ISDIR(dentry->d_inode->i_mode))
298 simple_rmdir(parent->d_inode, dentry);
299 else
300 simple_unlink(parent->d_inode, dentry);
301 dput(dentry);
302 }
303 }
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800304 mutex_unlock(&parent->d_inode->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700305 simple_release_fs(&mount, &mount_count);
306}
307EXPORT_SYMBOL_GPL(securityfs_remove);
308
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100309static struct kobject *security_kobj;
Greg KHb67dbf92005-07-07 14:37:53 -0700310
311static int __init securityfs_init(void)
312{
313 int retval;
314
Greg Kroah-Hartman0ff21e42007-11-06 10:36:58 -0800315 security_kobj = kobject_create_and_add("security", kernel_kobj);
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100316 if (!security_kobj)
317 return -EINVAL;
Greg KHb67dbf92005-07-07 14:37:53 -0700318
319 retval = register_filesystem(&fs_type);
320 if (retval)
Greg Kroah-Hartman78a2d902007-12-20 08:13:05 -0800321 kobject_put(security_kobj);
Greg KHb67dbf92005-07-07 14:37:53 -0700322 return retval;
323}
324
Greg KHb67dbf92005-07-07 14:37:53 -0700325core_initcall(securityfs_init);
Greg KHb67dbf92005-07-07 14:37:53 -0700326MODULE_LICENSE("GPL");
327