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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
Greg KHb67dbf92005-07-07 14:37:53 -070028static inline int positive(struct dentry *dentry)
29{
David Howellsce0b16d2015-02-19 10:47:02 +000030 return d_really_is_positive(dentry) && !d_unhashed(dentry);
Greg KHb67dbf92005-07-07 14:37:53 -070031}
32
33static int fill_super(struct super_block *sb, void *data, int silent)
34{
35 static struct tree_descr files[] = {{""}};
36
37 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
38}
39
Al Virofc14f2f2010-07-25 01:48:30 +040040static struct dentry *get_sb(struct file_system_type *fs_type,
David Howells454e2392006-06-23 02:02:57 -070041 int flags, const char *dev_name,
Al Virofc14f2f2010-07-25 01:48:30 +040042 void *data)
Greg KHb67dbf92005-07-07 14:37:53 -070043{
Al Virofc14f2f2010-07-25 01:48:30 +040044 return mount_single(fs_type, flags, data, fill_super);
Greg KHb67dbf92005-07-07 14:37:53 -070045}
46
47static struct file_system_type fs_type = {
48 .owner = THIS_MODULE,
49 .name = "securityfs",
Al Virofc14f2f2010-07-25 01:48:30 +040050 .mount = get_sb,
Greg KHb67dbf92005-07-07 14:37:53 -070051 .kill_sb = kill_litter_super,
52};
53
Greg KHb67dbf92005-07-07 14:37:53 -070054/**
55 * securityfs_create_file - create a file in the securityfs filesystem
56 *
57 * @name: a pointer to a string containing the name of the file to create.
58 * @mode: the permission that the file should have
59 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -070060 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -070061 * file will be created in the root of the securityfs filesystem.
62 * @data: a pointer to something that the caller will want to get to later
Theodore Ts'o8e18e292006-09-27 01:50:46 -070063 * on. The inode.i_private pointer will point to this value on
Greg KHb67dbf92005-07-07 14:37:53 -070064 * the open() call.
65 * @fops: a pointer to a struct file_operations that should be used for
66 * this file.
67 *
68 * This is the basic "create a file" function for securityfs. It allows for a
Randy Dunlap3f23d812008-08-17 21:44:22 -070069 * wide range of flexibility in creating a file, or a directory (if you
Greg KHb67dbf92005-07-07 14:37:53 -070070 * want to create a directory, the securityfs_create_dir() function is
Randy Dunlap3f23d812008-08-17 21:44:22 -070071 * recommended to be used instead).
Greg KHb67dbf92005-07-07 14:37:53 -070072 *
Randy Dunlap3f23d812008-08-17 21:44:22 -070073 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -070074 * pointer must be passed to the securityfs_remove() function when the file is
75 * to be removed (no automatic cleanup happens if your module is unloaded,
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -080076 * you are responsible here). If an error occurs, the function will return
Masanari Iidada3dae52014-09-09 01:27:23 +090077 * the error value (via ERR_PTR).
Greg KHb67dbf92005-07-07 14:37:53 -070078 *
Randy Dunlap3f23d812008-08-17 21:44:22 -070079 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -080080 * returned.
Greg KHb67dbf92005-07-07 14:37:53 -070081 */
Al Viro52ef0c02011-07-26 04:30:04 -040082struct dentry *securityfs_create_file(const char *name, umode_t mode,
Greg KHb67dbf92005-07-07 14:37:53 -070083 struct dentry *parent, void *data,
Arjan van de Ven9c2e08c2007-02-12 00:55:37 -080084 const struct file_operations *fops)
Greg KHb67dbf92005-07-07 14:37:53 -070085{
Al Viro3e25eb92012-01-10 10:20:35 -050086 struct dentry *dentry;
87 int is_dir = S_ISDIR(mode);
88 struct inode *dir, *inode;
Greg KHb67dbf92005-07-07 14:37:53 -070089 int error;
90
Al Viro3e25eb92012-01-10 10:20:35 -050091 if (!is_dir) {
92 BUG_ON(!fops);
93 mode = (mode & S_IALLUGO) | S_IFREG;
94 }
95
Greg KHb67dbf92005-07-07 14:37:53 -070096 pr_debug("securityfs: creating file '%s'\n",name);
97
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -040098 error = simple_pin_fs(&fs_type, &mount, &mount_count);
Al Viro3e25eb92012-01-10 10:20:35 -050099 if (error)
100 return ERR_PTR(error);
Greg KHb67dbf92005-07-07 14:37:53 -0700101
Al Viro3e25eb92012-01-10 10:20:35 -0500102 if (!parent)
103 parent = mount->mnt_root;
104
David Howellsce0b16d2015-02-19 10:47:02 +0000105 dir = d_inode(parent);
Al Viro3e25eb92012-01-10 10:20:35 -0500106
107 mutex_lock(&dir->i_mutex);
108 dentry = lookup_one_len(name, parent, strlen(name));
109 if (IS_ERR(dentry))
110 goto out;
Greg KHb67dbf92005-07-07 14:37:53 -0700111
David Howellsce0b16d2015-02-19 10:47:02 +0000112 if (d_really_is_positive(dentry)) {
Al Viro3e25eb92012-01-10 10:20:35 -0500113 error = -EEXIST;
114 goto out1;
Greg KHb67dbf92005-07-07 14:37:53 -0700115 }
Al Viro3e25eb92012-01-10 10:20:35 -0500116
117 inode = new_inode(dir->i_sb);
118 if (!inode) {
119 error = -ENOMEM;
120 goto out1;
121 }
122
123 inode->i_ino = get_next_ino();
124 inode->i_mode = mode;
125 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
126 inode->i_private = data;
127 if (is_dir) {
128 inode->i_op = &simple_dir_inode_operations;
129 inode->i_fop = &simple_dir_operations;
130 inc_nlink(inode);
131 inc_nlink(dir);
132 } else {
133 inode->i_fop = fops;
134 }
135 d_instantiate(dentry, inode);
136 dget(dentry);
137 mutex_unlock(&dir->i_mutex);
138 return dentry;
139
140out1:
141 dput(dentry);
142 dentry = ERR_PTR(error);
143out:
144 mutex_unlock(&dir->i_mutex);
145 simple_release_fs(&mount, &mount_count);
Greg KHb67dbf92005-07-07 14:37:53 -0700146 return dentry;
147}
148EXPORT_SYMBOL_GPL(securityfs_create_file);
149
150/**
151 * securityfs_create_dir - create a directory in the securityfs filesystem
152 *
153 * @name: a pointer to a string containing the name of the directory to
154 * create.
155 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700156 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700157 * directory will be created in the root of the securityfs filesystem.
158 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700159 * This function creates a directory in securityfs with the given @name.
Greg KHb67dbf92005-07-07 14:37:53 -0700160 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700161 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700162 * pointer must be passed to the securityfs_remove() function when the file is
163 * to be removed (no automatic cleanup happens if your module is unloaded,
Randy Dunlap3f23d812008-08-17 21:44:22 -0700164 * you are responsible here). If an error occurs, %NULL will be returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700165 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700166 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Greg KHb67dbf92005-07-07 14:37:53 -0700167 * returned. It is not wise to check for this value, but rather, check for
Randy Dunlap3f23d812008-08-17 21:44:22 -0700168 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
Greg KHb67dbf92005-07-07 14:37:53 -0700169 * code.
170 */
171struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
172{
173 return securityfs_create_file(name,
174 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
175 parent, NULL, NULL);
176}
177EXPORT_SYMBOL_GPL(securityfs_create_dir);
178
179/**
180 * securityfs_remove - removes a file or directory from the securityfs filesystem
181 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700182 * @dentry: a pointer to a the dentry of the file or directory to be removed.
Greg KHb67dbf92005-07-07 14:37:53 -0700183 *
184 * This function removes a file or directory in securityfs that was previously
185 * created with a call to another securityfs function (like
186 * securityfs_create_file() or variants thereof.)
187 *
188 * This function is required to be called in order for the file to be
Randy Dunlap3f23d812008-08-17 21:44:22 -0700189 * removed. No automatic cleanup of files will happen when a module is
190 * removed; you are responsible here.
Greg KHb67dbf92005-07-07 14:37:53 -0700191 */
192void securityfs_remove(struct dentry *dentry)
193{
194 struct dentry *parent;
195
Eric Parisd93e4c92009-05-11 20:47:15 -0400196 if (!dentry || IS_ERR(dentry))
Greg KHb67dbf92005-07-07 14:37:53 -0700197 return;
198
199 parent = dentry->d_parent;
David Howellsce0b16d2015-02-19 10:47:02 +0000200 if (!parent || d_really_is_negative(parent))
Greg KHb67dbf92005-07-07 14:37:53 -0700201 return;
202
David Howellsce0b16d2015-02-19 10:47:02 +0000203 mutex_lock(&d_inode(parent)->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700204 if (positive(dentry)) {
David Howellsce0b16d2015-02-19 10:47:02 +0000205 if (d_really_is_positive(dentry)) {
David Howellse36cb0b2015-01-29 12:02:35 +0000206 if (d_is_dir(dentry))
David Howellsce0b16d2015-02-19 10:47:02 +0000207 simple_rmdir(d_inode(parent), dentry);
Greg KHb67dbf92005-07-07 14:37:53 -0700208 else
David Howellsce0b16d2015-02-19 10:47:02 +0000209 simple_unlink(d_inode(parent), dentry);
Greg KHb67dbf92005-07-07 14:37:53 -0700210 dput(dentry);
211 }
212 }
David Howellsce0b16d2015-02-19 10:47:02 +0000213 mutex_unlock(&d_inode(parent)->i_mutex);
Greg KHb67dbf92005-07-07 14:37:53 -0700214 simple_release_fs(&mount, &mount_count);
215}
216EXPORT_SYMBOL_GPL(securityfs_remove);
217
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100218static struct kobject *security_kobj;
Greg KHb67dbf92005-07-07 14:37:53 -0700219
220static int __init securityfs_init(void)
221{
222 int retval;
223
Greg Kroah-Hartman0ff21e42007-11-06 10:36:58 -0800224 security_kobj = kobject_create_and_add("security", kernel_kobj);
Greg Kroah-Hartman69d8e132007-10-29 20:13:17 +0100225 if (!security_kobj)
226 return -EINVAL;
Greg KHb67dbf92005-07-07 14:37:53 -0700227
228 retval = register_filesystem(&fs_type);
229 if (retval)
Greg Kroah-Hartman78a2d902007-12-20 08:13:05 -0800230 kobject_put(security_kobj);
Greg KHb67dbf92005-07-07 14:37:53 -0700231 return retval;
232}
233
Greg KHb67dbf92005-07-07 14:37:53 -0700234core_initcall(securityfs_init);
Greg KHb67dbf92005-07-07 14:37:53 -0700235MODULE_LICENSE("GPL");
236