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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 */
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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>
d69dece5 23#include <linux/lsm_hooks.h>
92562927 24#include <linux/magic.h>
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25
26static struct vfsmount *mount;
27static int mount_count;
28
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29static int fill_super(struct super_block *sb, void *data, int silent)
30{
cda37124 31 static const struct tree_descr files[] = {{""}};
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32
33 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
34}
35
fc14f2fe 36static struct dentry *get_sb(struct file_system_type *fs_type,
454e2398 37 int flags, const char *dev_name,
fc14f2fe 38 void *data)
b67dbf9d 39{
fc14f2fe 40 return mount_single(fs_type, flags, data, fill_super);
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41}
42
43static struct file_system_type fs_type = {
44 .owner = THIS_MODULE,
45 .name = "securityfs",
fc14f2fe 46 .mount = get_sb,
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47 .kill_sb = kill_litter_super,
48};
49
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50/**
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
3f23d815 56 * directory dentry if set. If this parameter is %NULL, then the
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57 * 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
8e18e294 59 * on. The inode.i_private pointer will point to this value on
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60 * 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
3f23d815 65 * wide range of flexibility in creating a file, or a directory (if you
b67dbf9d 66 * want to create a directory, the securityfs_create_dir() function is
3f23d815 67 * recommended to be used instead).
b67dbf9d 68 *
3f23d815 69 * This function returns a pointer to a dentry if it succeeds. This
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70 * 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,
faa3aad7 72 * you are responsible here). If an error occurs, the function will return
da3dae54 73 * the error value (via ERR_PTR).
b67dbf9d 74 *
3f23d815 75 * If securityfs is not enabled in the kernel, the value %-ENODEV is
faa3aad7 76 * returned.
b67dbf9d 77 */
52ef0c04 78struct dentry *securityfs_create_file(const char *name, umode_t mode,
b67dbf9d 79 struct dentry *parent, void *data,
9c2e08c5 80 const struct file_operations *fops)
b67dbf9d 81{
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82 struct dentry *dentry;
83 int is_dir = S_ISDIR(mode);
84 struct inode *dir, *inode;
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85 int error;
86
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87 if (!is_dir) {
88 BUG_ON(!fops);
89 mode = (mode & S_IALLUGO) | S_IFREG;
90 }
91
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92 pr_debug("securityfs: creating file '%s'\n",name);
93
1f5ce9e9 94 error = simple_pin_fs(&fs_type, &mount, &mount_count);
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95 if (error)
96 return ERR_PTR(error);
97
98 if (!parent)
99 parent = mount->mnt_root;
100
ce0b16dd 101 dir = d_inode(parent);
3e25eb9c 102
5955102c 103 inode_lock(dir);
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104 dentry = lookup_one_len(name, parent, strlen(name));
105 if (IS_ERR(dentry))
106 goto out;
107
ce0b16dd 108 if (d_really_is_positive(dentry)) {
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109 error = -EEXIST;
110 goto out1;
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111 }
112
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113 inode = new_inode(dir->i_sb);
114 if (!inode) {
115 error = -ENOMEM;
116 goto out1;
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117 }
118
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119 inode->i_ino = get_next_ino();
120 inode->i_mode = mode;
078cd827 121 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
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122 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;
b67dbf9d 130 }
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131 d_instantiate(dentry, inode);
132 dget(dentry);
5955102c 133 inode_unlock(dir);
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134 return dentry;
135
136out1:
137 dput(dentry);
138 dentry = ERR_PTR(error);
139out:
5955102c 140 inode_unlock(dir);
3e25eb9c 141 simple_release_fs(&mount, &mount_count);
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142 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
3f23d815 152 * directory dentry if set. If this parameter is %NULL, then the
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153 * directory will be created in the root of the securityfs filesystem.
154 *
3f23d815 155 * This function creates a directory in securityfs with the given @name.
b67dbf9d 156 *
3f23d815 157 * This function returns a pointer to a dentry if it succeeds. This
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158 * 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,
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160 * you are responsible here). If an error occurs, the function will return
161 * the error value (via ERR_PTR).
b67dbf9d 162 *
3f23d815 163 * If securityfs is not enabled in the kernel, the value %-ENODEV is
1b460651 164 * returned.
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165 */
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 *
3f23d815 177 * @dentry: a pointer to a the dentry of the file or directory to be removed.
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178 *
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
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184 * removed. No automatic cleanup of files will happen when a module is
185 * removed; you are responsible here.
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186 */
187void securityfs_remove(struct dentry *dentry)
188{
4093d306 189 struct inode *dir;
b67dbf9d 190
d93e4c94 191 if (!dentry || IS_ERR(dentry))
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192 return;
193
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194 dir = d_inode(dentry->d_parent);
195 inode_lock(dir);
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196 if (simple_positive(dentry)) {
197 if (d_is_dir(dentry))
4093d306 198 simple_rmdir(dir, dentry);
dc3f4198 199 else
4093d306 200 simple_unlink(dir, dentry);
dc3f4198 201 dput(dentry);
b67dbf9d 202 }
4093d306 203 inode_unlock(dir);
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204 simple_release_fs(&mount, &mount_count);
205}
206EXPORT_SYMBOL_GPL(securityfs_remove);
207
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208#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
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223static int __init securityfs_init(void)
224{
225 int retval;
226
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227 retval = sysfs_create_mount_point(kernel_kobj, "security");
228 if (retval)
229 return retval;
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230
231 retval = register_filesystem(&fs_type);
d69dece5 232 if (retval) {
f9bb4882 233 sysfs_remove_mount_point(kernel_kobj, "security");
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234 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;
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241}
242
b67dbf9d 243core_initcall(securityfs_init);
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244MODULE_LICENSE("GPL");
245