path: root/security/inode.c (plain)
blob: b4531f2be0f1bb17af411b519ea94e5f8433111e

1	/*
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 */
16	#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>
23	#include <linux/magic.h>
24
25	static struct vfsmount *mount;
26	static int mount_count;
27
28	static int fill_super(struct super_block *sb, void *data, int silent)
29	{
30	static struct tree_descr files[] = {{""}};
31
32	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
33	}
34
35	static struct dentry *get_sb(struct file_system_type *fs_type,
36	int flags, const char *dev_name,
37	void *data)
38	{
39	return mount_single(fs_type, flags, data, fill_super);
40	}
41
42	static struct file_system_type fs_type = {
43	.owner = THIS_MODULE,
44	.name = "securityfs",
45	.mount = get_sb,
46	.kill_sb = kill_litter_super,
47	};
48
49	/**
50	* securityfs_create_file - create a file in the securityfs filesystem
51	*
52	* @name: a pointer to a string containing the name of the file to create.
53	* @mode: the permission that the file should have
54	* @parent: a pointer to the parent dentry for this file. This should be a
55	* directory dentry if set. If this parameter is %NULL, then the
56	* file will be created in the root of the securityfs filesystem.
57	* @data: a pointer to something that the caller will want to get to later
58	* on. The inode.i_private pointer will point to this value on
59	* the open() call.
60	* @fops: a pointer to a struct file_operations that should be used for
61	* this file.
62	*
63	* This is the basic "create a file" function for securityfs. It allows for a
64	* wide range of flexibility in creating a file, or a directory (if you
65	* want to create a directory, the securityfs_create_dir() function is
66	* recommended to be used instead).
67	*
68	* This function returns a pointer to a dentry if it succeeds. This
69	* pointer must be passed to the securityfs_remove() function when the file is
70	* to be removed (no automatic cleanup happens if your module is unloaded,
71	* you are responsible here). If an error occurs, the function will return
72	* the error value (via ERR_PTR).
73	*
74	* If securityfs is not enabled in the kernel, the value %-ENODEV is
75	* returned.
76	*/
77	struct dentry *securityfs_create_file(const char *name, umode_t mode,
78	struct dentry *parent, void *data,
79	const struct file_operations *fops)
80	{
81	struct dentry *dentry;
82	int is_dir = S_ISDIR(mode);
83	struct inode *dir, *inode;
84	int error;
85
86	if (!is_dir) {
87	BUG_ON(!fops);
88	mode = (mode & S_IALLUGO) | S_IFREG;
89	}
90
91	pr_debug("securityfs: creating file '%s'\n",name);
92
93	error = simple_pin_fs(&fs_type, &mount, &mount_count);
94	if (error)
95	return ERR_PTR(error);
96
97	if (!parent)
98	parent = mount->mnt_root;
99
100	dir = d_inode(parent);
101
102	inode_lock(dir);
103	dentry = lookup_one_len2(name, mount, parent, strlen(name));
104	if (IS_ERR(dentry))
105	goto out;
106
107	if (d_really_is_positive(dentry)) {
108	error = -EEXIST;
109	goto out1;
110	}
111
112	inode = new_inode(dir->i_sb);
113	if (!inode) {
114	error = -ENOMEM;
115	goto out1;
116	}
117
118	inode->i_ino = get_next_ino();
119	inode->i_mode = mode;
120	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
121	inode->i_private = data;
122	if (is_dir) {
123	inode->i_op = &simple_dir_inode_operations;
124	inode->i_fop = &simple_dir_operations;
125	inc_nlink(inode);
126	inc_nlink(dir);
127	} else {
128	inode->i_fop = fops;
129	}
130	d_instantiate(dentry, inode);
131	dget(dentry);
132	inode_unlock(dir);
133	return dentry;
134
135	out1:
136	dput(dentry);
137	dentry = ERR_PTR(error);
138	out:
139	inode_unlock(dir);
140	simple_release_fs(&mount, &mount_count);
141	return dentry;
142	}
143	EXPORT_SYMBOL_GPL(securityfs_create_file);
144
145	/**
146	* securityfs_create_dir - create a directory in the securityfs filesystem
147	*
148	* @name: a pointer to a string containing the name of the directory to
149	* create.
150	* @parent: a pointer to the parent dentry for this file. This should be a
151	* directory dentry if set. If this parameter is %NULL, then the
152	* directory will be created in the root of the securityfs filesystem.
153	*
154	* This function creates a directory in securityfs with the given @name.
155	*
156	* This function returns a pointer to a dentry if it succeeds. This
157	* pointer must be passed to the securityfs_remove() function when the file is
158	* to be removed (no automatic cleanup happens if your module is unloaded,
159	* you are responsible here). If an error occurs, the function will return
160	* the error value (via ERR_PTR).
161	*
162	* If securityfs is not enabled in the kernel, the value %-ENODEV is
163	* returned.
164	*/
165	struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
166	{
167	return securityfs_create_file(name,
168	S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
169	parent, NULL, NULL);
170	}
171	EXPORT_SYMBOL_GPL(securityfs_create_dir);
172
173	/**
174	* securityfs_remove - removes a file or directory from the securityfs filesystem
175	*
176	* @dentry: a pointer to a the dentry of the file or directory to be removed.
177	*
178	* This function removes a file or directory in securityfs that was previously
179	* created with a call to another securityfs function (like
180	* securityfs_create_file() or variants thereof.)
181	*
182	* This function is required to be called in order for the file to be
183	* removed. No automatic cleanup of files will happen when a module is
184	* removed; you are responsible here.
185	*/
186	void securityfs_remove(struct dentry *dentry)
187	{
188	struct inode *dir;
189
190	if (!dentry || IS_ERR(dentry))
191	return;
192
193	dir = d_inode(dentry->d_parent);
194	inode_lock(dir);
195	if (simple_positive(dentry)) {
196	if (d_is_dir(dentry))
197	simple_rmdir(dir, dentry);
198	else
199	simple_unlink(dir, dentry);
200	dput(dentry);
201	}
202	inode_unlock(dir);
203	simple_release_fs(&mount, &mount_count);
204	}
205	EXPORT_SYMBOL_GPL(securityfs_remove);
206
207	static int __init securityfs_init(void)
208	{
209	int retval;
210
211	retval = sysfs_create_mount_point(kernel_kobj, "security");
212	if (retval)
213	return retval;
214
215	retval = register_filesystem(&fs_type);
216	if (retval)
217	sysfs_remove_mount_point(kernel_kobj, "security");
218	return retval;
219	}
220
221	core_initcall(securityfs_init);
222	MODULE_LICENSE("GPL");
223
224