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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>
Casey Schauflerd69dece2017-01-18 17:09:05 -080023#include <linux/lsm_hooks.h>
Mimi Zohar92562922008-10-07 14:00:12 -040024#include <linux/magic.h>
Greg KHb67dbf92005-07-07 14:37:53 -070025
26static struct vfsmount *mount;
27static int mount_count;
28
Greg KHb67dbf92005-07-07 14:37:53 -070029static int fill_super(struct super_block *sb, void *data, int silent)
30{
Eric Biggerscda37122017-03-25 21:15:37 -070031 static const struct tree_descr files[] = {{""}};
Greg KHb67dbf92005-07-07 14:37:53 -070032
33 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
34}
35
Al Virofc14f2f2010-07-25 01:48:30 +040036static struct dentry *get_sb(struct file_system_type *fs_type,
David Howells454e2392006-06-23 02:02:57 -070037 int flags, const char *dev_name,
Al Virofc14f2f2010-07-25 01:48:30 +040038 void *data)
Greg KHb67dbf92005-07-07 14:37:53 -070039{
Al Virofc14f2f2010-07-25 01:48:30 +040040 return mount_single(fs_type, flags, data, fill_super);
Greg KHb67dbf92005-07-07 14:37:53 -070041}
42
43static struct file_system_type fs_type = {
44 .owner = THIS_MODULE,
45 .name = "securityfs",
Al Virofc14f2f2010-07-25 01:48:30 +040046 .mount = get_sb,
Greg KHb67dbf92005-07-07 14:37:53 -070047 .kill_sb = kill_litter_super,
48};
49
Greg KHb67dbf92005-07-07 14:37:53 -070050/**
51 * securityfs_create_file - create a file in the securityfs filesystem
52 *
53 * @name: a pointer to a string containing the name of the file to create.
54 * @mode: the permission that the file should have
55 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -070056 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -070057 * file will be created in the root of the securityfs filesystem.
58 * @data: a pointer to something that the caller will want to get to later
Theodore Ts'o8e18e292006-09-27 01:50:46 -070059 * on. The inode.i_private pointer will point to this value on
Greg KHb67dbf92005-07-07 14:37:53 -070060 * the open() call.
61 * @fops: a pointer to a struct file_operations that should be used for
62 * this file.
63 *
64 * This is the basic "create a file" function for securityfs. It allows for a
Randy Dunlap3f23d812008-08-17 21:44:22 -070065 * wide range of flexibility in creating a file, or a directory (if you
Greg KHb67dbf92005-07-07 14:37:53 -070066 * want to create a directory, the securityfs_create_dir() function is
Randy Dunlap3f23d812008-08-17 21:44:22 -070067 * recommended to be used instead).
Greg KHb67dbf92005-07-07 14:37:53 -070068 *
Randy Dunlap3f23d812008-08-17 21:44:22 -070069 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -070070 * pointer must be passed to the securityfs_remove() function when the file is
71 * to be removed (no automatic cleanup happens if your module is unloaded,
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -080072 * you are responsible here). If an error occurs, the function will return
Masanari Iidada3dae52014-09-09 01:27:23 +090073 * the error value (via ERR_PTR).
Greg KHb67dbf92005-07-07 14:37:53 -070074 *
Randy Dunlap3f23d812008-08-17 21:44:22 -070075 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Serge E. Hallynfaa3aad2009-02-02 15:07:33 -080076 * returned.
Greg KHb67dbf92005-07-07 14:37:53 -070077 */
Al Viro52ef0c02011-07-26 04:30:04 -040078struct dentry *securityfs_create_file(const char *name, umode_t mode,
Greg KHb67dbf92005-07-07 14:37:53 -070079 struct dentry *parent, void *data,
Arjan van de Ven9c2e08c2007-02-12 00:55:37 -080080 const struct file_operations *fops)
Greg KHb67dbf92005-07-07 14:37:53 -070081{
Al Viro3e25eb92012-01-10 10:20:35 -050082 struct dentry *dentry;
83 int is_dir = S_ISDIR(mode);
84 struct inode *dir, *inode;
Greg KHb67dbf92005-07-07 14:37:53 -070085 int error;
86
Al Viro3e25eb92012-01-10 10:20:35 -050087 if (!is_dir) {
88 BUG_ON(!fops);
89 mode = (mode & S_IALLUGO) | S_IFREG;
90 }
91
Greg KHb67dbf92005-07-07 14:37:53 -070092 pr_debug("securityfs: creating file '%s'\n",name);
93
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -040094 error = simple_pin_fs(&fs_type, &mount, &mount_count);
Al Viro3e25eb92012-01-10 10:20:35 -050095 if (error)
96 return ERR_PTR(error);
Greg KHb67dbf92005-07-07 14:37:53 -070097
Al Viro3e25eb92012-01-10 10:20:35 -050098 if (!parent)
99 parent = mount->mnt_root;
100
David Howellsce0b16d2015-02-19 10:47:02 +0000101 dir = d_inode(parent);
Al Viro3e25eb92012-01-10 10:20:35 -0500102
Al Viro59551022016-01-22 15:40:57 -0500103 inode_lock(dir);
Al Viro3e25eb92012-01-10 10:20:35 -0500104 dentry = lookup_one_len(name, parent, strlen(name));
105 if (IS_ERR(dentry))
106 goto out;
Greg KHb67dbf92005-07-07 14:37:53 -0700107
David Howellsce0b16d2015-02-19 10:47:02 +0000108 if (d_really_is_positive(dentry)) {
Al Viro3e25eb92012-01-10 10:20:35 -0500109 error = -EEXIST;
110 goto out1;
Greg KHb67dbf92005-07-07 14:37:53 -0700111 }
Al Viro3e25eb92012-01-10 10:20:35 -0500112
113 inode = new_inode(dir->i_sb);
114 if (!inode) {
115 error = -ENOMEM;
116 goto out1;
117 }
118
119 inode->i_ino = get_next_ino();
120 inode->i_mode = mode;
Deepa Dinamani078cd822016-09-14 07:48:04 -0700121 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
Al Viro3e25eb92012-01-10 10:20:35 -0500122 inode->i_private = data;
123 if (is_dir) {
124 inode->i_op = &simple_dir_inode_operations;
125 inode->i_fop = &simple_dir_operations;
126 inc_nlink(inode);
127 inc_nlink(dir);
128 } else {
129 inode->i_fop = fops;
130 }
131 d_instantiate(dentry, inode);
132 dget(dentry);
Al Viro59551022016-01-22 15:40:57 -0500133 inode_unlock(dir);
Al Viro3e25eb92012-01-10 10:20:35 -0500134 return dentry;
135
136out1:
137 dput(dentry);
138 dentry = ERR_PTR(error);
139out:
Al Viro59551022016-01-22 15:40:57 -0500140 inode_unlock(dir);
Al Viro3e25eb92012-01-10 10:20:35 -0500141 simple_release_fs(&mount, &mount_count);
Greg KHb67dbf92005-07-07 14:37:53 -0700142 return dentry;
143}
144EXPORT_SYMBOL_GPL(securityfs_create_file);
145
146/**
147 * securityfs_create_dir - create a directory in the securityfs filesystem
148 *
149 * @name: a pointer to a string containing the name of the directory to
150 * create.
151 * @parent: a pointer to the parent dentry for this file. This should be a
Randy Dunlap3f23d812008-08-17 21:44:22 -0700152 * directory dentry if set. If this parameter is %NULL, then the
Greg KHb67dbf92005-07-07 14:37:53 -0700153 * directory will be created in the root of the securityfs filesystem.
154 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700155 * This function creates a directory in securityfs with the given @name.
Greg KHb67dbf92005-07-07 14:37:53 -0700156 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700157 * This function returns a pointer to a dentry if it succeeds. This
Greg KHb67dbf92005-07-07 14:37:53 -0700158 * pointer must be passed to the securityfs_remove() function when the file is
159 * to be removed (no automatic cleanup happens if your module is unloaded,
Laurent Georget1b460652016-07-13 08:58:40 +0200160 * you are responsible here). If an error occurs, the function will return
161 * the error value (via ERR_PTR).
Greg KHb67dbf92005-07-07 14:37:53 -0700162 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700163 * If securityfs is not enabled in the kernel, the value %-ENODEV is
Laurent Georget1b460652016-07-13 08:58:40 +0200164 * returned.
Greg KHb67dbf92005-07-07 14:37:53 -0700165 */
166struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
167{
168 return securityfs_create_file(name,
169 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
170 parent, NULL, NULL);
171}
172EXPORT_SYMBOL_GPL(securityfs_create_dir);
173
174/**
175 * securityfs_remove - removes a file or directory from the securityfs filesystem
176 *
Randy Dunlap3f23d812008-08-17 21:44:22 -0700177 * @dentry: a pointer to a the dentry of the file or directory to be removed.
Greg KHb67dbf92005-07-07 14:37:53 -0700178 *
179 * This function removes a file or directory in securityfs that was previously
180 * created with a call to another securityfs function (like
181 * securityfs_create_file() or variants thereof.)
182 *
183 * This function is required to be called in order for the file to be
Randy Dunlap3f23d812008-08-17 21:44:22 -0700184 * removed. No automatic cleanup of files will happen when a module is
185 * removed; you are responsible here.
Greg KHb67dbf92005-07-07 14:37:53 -0700186 */
187void securityfs_remove(struct dentry *dentry)
188{
Al Viro4093d302016-05-29 14:54:04 -0400189 struct inode *dir;
Greg KHb67dbf92005-07-07 14:37:53 -0700190
Eric Parisd93e4c92009-05-11 20:47:15 -0400191 if (!dentry || IS_ERR(dentry))
Greg KHb67dbf92005-07-07 14:37:53 -0700192 return;
193
Al Viro4093d302016-05-29 14:54:04 -0400194 dir = d_inode(dentry->d_parent);
195 inode_lock(dir);
Al Virodc3f4192015-05-18 10:10:34 -0400196 if (simple_positive(dentry)) {
197 if (d_is_dir(dentry))
Al Viro4093d302016-05-29 14:54:04 -0400198 simple_rmdir(dir, dentry);
Al Virodc3f4192015-05-18 10:10:34 -0400199 else
Al Viro4093d302016-05-29 14:54:04 -0400200 simple_unlink(dir, dentry);
Al Virodc3f4192015-05-18 10:10:34 -0400201 dput(dentry);
Greg KHb67dbf92005-07-07 14:37:53 -0700202 }
Al Viro4093d302016-05-29 14:54:04 -0400203 inode_unlock(dir);
Greg KHb67dbf92005-07-07 14:37:53 -0700204 simple_release_fs(&mount, &mount_count);
205}
206EXPORT_SYMBOL_GPL(securityfs_remove);
207
Casey Schauflerd69dece2017-01-18 17:09:05 -0800208#ifdef CONFIG_SECURITY
209static struct dentry *lsm_dentry;
210static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
211 loff_t *ppos)
212{
213 return simple_read_from_buffer(buf, count, ppos, lsm_names,
214 strlen(lsm_names));
215}
216
217static const struct file_operations lsm_ops = {
218 .read = lsm_read,
219 .llseek = generic_file_llseek,
220};
221#endif
222
Greg KHb67dbf92005-07-07 14:37:53 -0700223static int __init securityfs_init(void)
224{
225 int retval;
226
Eric W. Biedermanf9bb4882015-05-13 17:35:41 -0500227 retval = sysfs_create_mount_point(kernel_kobj, "security");
228 if (retval)
229 return retval;
Greg KHb67dbf92005-07-07 14:37:53 -0700230
231 retval = register_filesystem(&fs_type);
Casey Schauflerd69dece2017-01-18 17:09:05 -0800232 if (retval) {
Eric W. Biedermanf9bb4882015-05-13 17:35:41 -0500233 sysfs_remove_mount_point(kernel_kobj, "security");
Casey Schauflerd69dece2017-01-18 17:09:05 -0800234 return retval;
235 }
236#ifdef CONFIG_SECURITY
237 lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL,
238 &lsm_ops);
239#endif
240 return 0;
Greg KHb67dbf92005-07-07 14:37:53 -0700241}
242
Greg KHb67dbf92005-07-07 14:37:53 -0700243core_initcall(securityfs_init);
Greg KHb67dbf92005-07-07 14:37:53 -0700244MODULE_LICENSE("GPL");
245