4 * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
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.
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.
16 #include <linux/module.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>
23 #include <linux/magic.h>
25 static struct vfsmount *mount;
26 static int mount_count;
30 * I think I can get rid of these default_file_ops, but not quite sure...
32 static ssize_t default_read_file(struct file *file, char __user *buf,
33 size_t count, loff_t *ppos)
38 static ssize_t default_write_file(struct file *file, const char __user *buf,
39 size_t count, loff_t *ppos)
44 static int default_open(struct inode *inode, struct file *file)
47 file->private_data = inode->i_private;
52 static const struct file_operations default_file_ops = {
53 .read = default_read_file,
54 .write = default_write_file,
58 static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
60 struct inode *inode = new_inode(sb);
64 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
65 switch (mode & S_IFMT) {
67 init_special_inode(inode, mode, dev);
70 inode->i_fop = &default_file_ops;
73 inode->i_op = &simple_dir_inode_operations;
74 inode->i_fop = &simple_dir_operations;
76 /* directory inodes start off with i_nlink == 2 (for "." entry) */
85 static int mknod(struct inode *dir, struct dentry *dentry,
94 inode = get_inode(dir->i_sb, mode, dev);
96 d_instantiate(dentry, inode);
103 static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
107 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
108 res = mknod(dir, dentry, mode, 0);
114 static int create(struct inode *dir, struct dentry *dentry, int mode)
116 mode = (mode & S_IALLUGO) | S_IFREG;
117 return mknod(dir, dentry, mode, 0);
120 static inline int positive(struct dentry *dentry)
122 return dentry->d_inode && !d_unhashed(dentry);
125 static int fill_super(struct super_block *sb, void *data, int silent)
127 static struct tree_descr files[] = {{""}};
129 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
132 static int get_sb(struct file_system_type *fs_type,
133 int flags, const char *dev_name,
134 void *data, struct vfsmount *mnt)
136 return get_sb_single(fs_type, flags, data, fill_super, mnt);
139 static struct file_system_type fs_type = {
140 .owner = THIS_MODULE,
141 .name = "securityfs",
143 .kill_sb = kill_litter_super,
146 static int create_by_name(const char *name, mode_t mode,
147 struct dentry *parent,
148 struct dentry **dentry)
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
160 if (mount && mount->mnt_sb) {
161 parent = mount->mnt_sb->s_root;
165 pr_debug("securityfs: Ah! can not find a parent!\n");
169 mutex_lock(&parent->d_inode->i_mutex);
170 *dentry = lookup_one_len(name, parent, strlen(name));
171 if (!IS_ERR(dentry)) {
172 if ((mode & S_IFMT) == S_IFDIR)
173 error = mkdir(parent->d_inode, *dentry, mode);
175 error = create(parent->d_inode, *dentry, mode);
177 error = PTR_ERR(dentry);
178 mutex_unlock(&parent->d_inode->i_mutex);
184 * securityfs_create_file - create a file in the securityfs filesystem
186 * @name: a pointer to a string containing the name of the file to create.
187 * @mode: the permission that the file should have
188 * @parent: a pointer to the parent dentry for this file. This should be a
189 * directory dentry if set. If this parameter is %NULL, then the
190 * file will be created in the root of the securityfs filesystem.
191 * @data: a pointer to something that the caller will want to get to later
192 * on. The inode.i_private pointer will point to this value on
194 * @fops: a pointer to a struct file_operations that should be used for
197 * This is the basic "create a file" function for securityfs. It allows for a
198 * wide range of flexibility in creating a file, or a directory (if you
199 * want to create a directory, the securityfs_create_dir() function is
200 * recommended to be used instead).
202 * This function returns a pointer to a dentry if it succeeds. This
203 * pointer must be passed to the securityfs_remove() function when the file is
204 * to be removed (no automatic cleanup happens if your module is unloaded,
205 * you are responsible here). If an error occurs, the function will return
206 * the erorr value (via ERR_PTR).
208 * If securityfs is not enabled in the kernel, the value %-ENODEV is
211 struct dentry *securityfs_create_file(const char *name, mode_t mode,
212 struct dentry *parent, void *data,
213 const struct file_operations *fops)
215 struct dentry *dentry = NULL;
218 pr_debug("securityfs: creating file '%s'\n",name);
220 error = simple_pin_fs(&fs_type, &mount, &mount_count);
222 dentry = ERR_PTR(error);
226 error = create_by_name(name, mode, parent, &dentry);
228 dentry = ERR_PTR(error);
229 simple_release_fs(&mount, &mount_count);
233 if (dentry->d_inode) {
235 dentry->d_inode->i_fop = fops;
237 dentry->d_inode->i_private = data;
242 EXPORT_SYMBOL_GPL(securityfs_create_file);
245 * securityfs_create_dir - create a directory in the securityfs filesystem
247 * @name: a pointer to a string containing the name of the directory to
249 * @parent: a pointer to the parent dentry for this file. This should be a
250 * directory dentry if set. If this parameter is %NULL, then the
251 * directory will be created in the root of the securityfs filesystem.
253 * This function creates a directory in securityfs with the given @name.
255 * This function returns a pointer to a dentry if it succeeds. This
256 * pointer must be passed to the securityfs_remove() function when the file is
257 * to be removed (no automatic cleanup happens if your module is unloaded,
258 * you are responsible here). If an error occurs, %NULL will be returned.
260 * If securityfs is not enabled in the kernel, the value %-ENODEV is
261 * returned. It is not wise to check for this value, but rather, check for
262 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
265 struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
267 return securityfs_create_file(name,
268 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
271 EXPORT_SYMBOL_GPL(securityfs_create_dir);
274 * securityfs_remove - removes a file or directory from the securityfs filesystem
276 * @dentry: a pointer to a the dentry of the file or directory to be removed.
278 * This function removes a file or directory in securityfs that was previously
279 * created with a call to another securityfs function (like
280 * securityfs_create_file() or variants thereof.)
282 * This function is required to be called in order for the file to be
283 * removed. No automatic cleanup of files will happen when a module is
284 * removed; you are responsible here.
286 void securityfs_remove(struct dentry *dentry)
288 struct dentry *parent;
290 if (!dentry || IS_ERR(dentry))
293 parent = dentry->d_parent;
294 if (!parent || !parent->d_inode)
297 mutex_lock(&parent->d_inode->i_mutex);
298 if (positive(dentry)) {
299 if (dentry->d_inode) {
300 if (S_ISDIR(dentry->d_inode->i_mode))
301 simple_rmdir(parent->d_inode, dentry);
303 simple_unlink(parent->d_inode, dentry);
307 mutex_unlock(&parent->d_inode->i_mutex);
308 simple_release_fs(&mount, &mount_count);
310 EXPORT_SYMBOL_GPL(securityfs_remove);
312 static struct kobject *security_kobj;
314 static int __init securityfs_init(void)
318 security_kobj = kobject_create_and_add("security", kernel_kobj);
322 retval = register_filesystem(&fs_type);
324 kobject_put(security_kobj);
328 core_initcall(securityfs_init);
329 MODULE_LICENSE("GPL");