blob: a5964502ae30df2e5ab16397769866f57d919bc4 [file] [log] [blame]
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 */
16#include <linux/config.h>
17#include <linux/module.h>
18#include <linux/fs.h>
19#include <linux/mount.h>
20#include <linux/pagemap.h>
21#include <linux/init.h>
22#include <linux/namei.h>
23#include <linux/security.h>
24
25#define SECURITYFS_MAGIC 0x73636673
26
27static struct vfsmount *mount;
28static int mount_count;
29
30/*
31 * TODO:
32 * I think I can get rid of these default_file_ops, but not quite sure...
33 */
34static ssize_t default_read_file(struct file *file, char __user *buf,
35 size_t count, loff_t *ppos)
36{
37 return 0;
38}
39
40static ssize_t default_write_file(struct file *file, const char __user *buf,
41 size_t count, loff_t *ppos)
42{
43 return count;
44}
45
46static int default_open(struct inode *inode, struct file *file)
47{
48 if (inode->u.generic_ip)
49 file->private_data = inode->u.generic_ip;
50
51 return 0;
52}
53
54static struct file_operations default_file_ops = {
55 .read = default_read_file,
56 .write = default_write_file,
57 .open = default_open,
58};
59
60static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
61{
62 struct inode *inode = new_inode(sb);
63
64 if (inode) {
65 inode->i_mode = mode;
66 inode->i_uid = 0;
67 inode->i_gid = 0;
68 inode->i_blksize = PAGE_CACHE_SIZE;
69 inode->i_blocks = 0;
70 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
71 switch (mode & S_IFMT) {
72 default:
73 init_special_inode(inode, mode, dev);
74 break;
75 case S_IFREG:
76 inode->i_fop = &default_file_ops;
77 break;
78 case S_IFDIR:
79 inode->i_op = &simple_dir_inode_operations;
80 inode->i_fop = &simple_dir_operations;
81
82 /* directory inodes start off with i_nlink == 2 (for "." entry) */
83 inode->i_nlink++;
84 break;
85 }
86 }
87 return inode;
88}
89
90/* SMP-safe */
91static int mknod(struct inode *dir, struct dentry *dentry,
92 int mode, dev_t dev)
93{
94 struct inode *inode;
95 int error = -EPERM;
96
97 if (dentry->d_inode)
98 return -EEXIST;
99
100 inode = get_inode(dir->i_sb, mode, dev);
101 if (inode) {
102 d_instantiate(dentry, inode);
103 dget(dentry);
104 error = 0;
105 }
106 return error;
107}
108
109static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
110{
111 int res;
112
113 mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
114 res = mknod(dir, dentry, mode, 0);
115 if (!res)
116 dir->i_nlink++;
117 return res;
118}
119
120static int create(struct inode *dir, struct dentry *dentry, int mode)
121{
122 mode = (mode & S_IALLUGO) | S_IFREG;
123 return mknod(dir, dentry, mode, 0);
124}
125
126static inline int positive(struct dentry *dentry)
127{
128 return dentry->d_inode && !d_unhashed(dentry);
129}
130
131static int fill_super(struct super_block *sb, void *data, int silent)
132{
133 static struct tree_descr files[] = {{""}};
134
135 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
136}
137
138static struct super_block *get_sb(struct file_system_type *fs_type,
139 int flags, const char *dev_name,
140 void *data)
141{
142 return get_sb_single(fs_type, flags, data, fill_super);
143}
144
145static struct file_system_type fs_type = {
146 .owner = THIS_MODULE,
147 .name = "securityfs",
148 .get_sb = get_sb,
149 .kill_sb = kill_litter_super,
150};
151
152static int create_by_name(const char *name, mode_t mode,
153 struct dentry *parent,
154 struct dentry **dentry)
155{
156 int error = 0;
157
158 *dentry = NULL;
159
160 /* If the parent is not specified, we create it in the root.
161 * We need the root dentry to do this, which is in the super
162 * block. A pointer to that is in the struct vfsmount that we
163 * have around.
164 */
165 if (!parent ) {
166 if (mount && mount->mnt_sb) {
167 parent = mount->mnt_sb->s_root;
168 }
169 }
170 if (!parent) {
171 pr_debug("securityfs: Ah! can not find a parent!\n");
172 return -EFAULT;
173 }
174
175 down(&parent->d_inode->i_sem);
176 *dentry = lookup_one_len(name, parent, strlen(name));
177 if (!IS_ERR(dentry)) {
178 if ((mode & S_IFMT) == S_IFDIR)
179 error = mkdir(parent->d_inode, *dentry, mode);
180 else
181 error = create(parent->d_inode, *dentry, mode);
182 } else
183 error = PTR_ERR(dentry);
184 up(&parent->d_inode->i_sem);
185
186 return error;
187}
188
189/**
190 * securityfs_create_file - create a file in the securityfs filesystem
191 *
192 * @name: a pointer to a string containing the name of the file to create.
193 * @mode: the permission that the file should have
194 * @parent: a pointer to the parent dentry for this file. This should be a
195 * directory dentry if set. If this paramater is NULL, then the
196 * file will be created in the root of the securityfs filesystem.
197 * @data: a pointer to something that the caller will want to get to later
198 * on. The inode.u.generic_ip pointer will point to this value on
199 * the open() call.
200 * @fops: a pointer to a struct file_operations that should be used for
201 * this file.
202 *
203 * This is the basic "create a file" function for securityfs. It allows for a
204 * wide range of flexibility in createing a file, or a directory (if you
205 * want to create a directory, the securityfs_create_dir() function is
206 * recommended to be used instead.)
207 *
208 * This function will return a pointer to a dentry if it succeeds. This
209 * pointer must be passed to the securityfs_remove() function when the file is
210 * to be removed (no automatic cleanup happens if your module is unloaded,
211 * you are responsible here.) If an error occurs, NULL will be returned.
212 *
213 * If securityfs is not enabled in the kernel, the value -ENODEV will be
214 * returned. It is not wise to check for this value, but rather, check for
215 * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
216 * code.
217 */
218struct dentry *securityfs_create_file(const char *name, mode_t mode,
219 struct dentry *parent, void *data,
220 struct file_operations *fops)
221{
222 struct dentry *dentry = NULL;
223 int error;
224
225 pr_debug("securityfs: creating file '%s'\n",name);
226
227 error = simple_pin_fs("securityfs", &mount, &mount_count);
228 if (error) {
229 dentry = ERR_PTR(error);
230 goto exit;
231 }
232
233 error = create_by_name(name, mode, parent, &dentry);
234 if (error) {
235 dentry = ERR_PTR(error);
236 simple_release_fs(&mount, &mount_count);
237 goto exit;
238 }
239
240 if (dentry->d_inode) {
241 if (fops)
242 dentry->d_inode->i_fop = fops;
243 if (data)
244 dentry->d_inode->u.generic_ip = data;
245 }
246exit:
247 return dentry;
248}
249EXPORT_SYMBOL_GPL(securityfs_create_file);
250
251/**
252 * securityfs_create_dir - create a directory in the securityfs filesystem
253 *
254 * @name: a pointer to a string containing the name of the directory to
255 * create.
256 * @parent: a pointer to the parent dentry for this file. This should be a
257 * directory dentry if set. If this paramater is NULL, then the
258 * directory will be created in the root of the securityfs filesystem.
259 *
260 * This function creates a directory in securityfs with the given name.
261 *
262 * This function will return a pointer to a dentry if it succeeds. This
263 * pointer must be passed to the securityfs_remove() function when the file is
264 * to be removed (no automatic cleanup happens if your module is unloaded,
265 * you are responsible here.) If an error occurs, NULL will be returned.
266 *
267 * If securityfs is not enabled in the kernel, the value -ENODEV will be
268 * returned. It is not wise to check for this value, but rather, check for
269 * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
270 * code.
271 */
272struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
273{
274 return securityfs_create_file(name,
275 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
276 parent, NULL, NULL);
277}
278EXPORT_SYMBOL_GPL(securityfs_create_dir);
279
280/**
281 * securityfs_remove - removes a file or directory from the securityfs filesystem
282 *
283 * @dentry: a pointer to a the dentry of the file or directory to be
284 * removed.
285 *
286 * This function removes a file or directory in securityfs that was previously
287 * created with a call to another securityfs function (like
288 * securityfs_create_file() or variants thereof.)
289 *
290 * This function is required to be called in order for the file to be
291 * removed, no automatic cleanup of files will happen when a module is
292 * removed, you are responsible here.
293 */
294void securityfs_remove(struct dentry *dentry)
295{
296 struct dentry *parent;
297
298 if (!dentry)
299 return;
300
301 parent = dentry->d_parent;
302 if (!parent || !parent->d_inode)
303 return;
304
305 down(&parent->d_inode->i_sem);
306 if (positive(dentry)) {
307 if (dentry->d_inode) {
308 if (S_ISDIR(dentry->d_inode->i_mode))
309 simple_rmdir(parent->d_inode, dentry);
310 else
311 simple_unlink(parent->d_inode, dentry);
312 dput(dentry);
313 }
314 }
315 up(&parent->d_inode->i_sem);
316 simple_release_fs(&mount, &mount_count);
317}
318EXPORT_SYMBOL_GPL(securityfs_remove);
319
320static decl_subsys(security, NULL, NULL);
321
322static int __init securityfs_init(void)
323{
324 int retval;
325
326 kset_set_kset_s(&security_subsys, kernel_subsys);
327 retval = subsystem_register(&security_subsys);
328 if (retval)
329 return retval;
330
331 retval = register_filesystem(&fs_type);
332 if (retval)
333 subsystem_unregister(&security_subsys);
334 return retval;
335}
336
337static void __exit securityfs_exit(void)
338{
339 simple_release_fs(&mount, &mount_count);
340 unregister_filesystem(&fs_type);
341 subsystem_unregister(&security_subsys);
342}
343
344core_initcall(securityfs_init);
345module_exit(securityfs_exit);
346MODULE_LICENSE("GPL");
347