summaryrefslogtreecommitdiffstats
path: root/security/inode.c
blob: 8dd9ca8848e4361fae0e3c1d15593a41c53ff18a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
/*
 *  inode.c - securityfs
 *
 *  Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License version
 *	2 as published by the Free Software Foundation.
 *
 *  Based on fs/debugfs/inode.c which had the following copyright notice:
 *    Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
 *    Copyright (C) 2004 IBM Inc.
 */

/* #define DEBUG */
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/lsm_hooks.h>
#include <linux/magic.h>

static struct vfsmount *mount;
static int mount_count;

static void securityfs_evict_inode(struct inode *inode)
{
	truncate_inode_pages_final(&inode->i_data);
	clear_inode(inode);
	if (S_ISLNK(inode->i_mode))
		kfree(inode->i_link);
}

static const struct super_operations securityfs_super_operations = {
	.statfs		= simple_statfs,
	.evict_inode	= securityfs_evict_inode,
};

static int fill_super(struct super_block *sb, void *data, int silent)
{
	static const struct tree_descr files[] = {{""}};
	int error;

	error = simple_fill_super(sb, SECURITYFS_MAGIC, files);
	if (error)
		return error;

	sb->s_op = &securityfs_super_operations;

	return 0;
}

static struct dentry *get_sb(struct file_system_type *fs_type,
		  int flags, const char *dev_name,
		  void *data)
{
	return mount_single(fs_type, flags, data, fill_super);
}

static struct file_system_type fs_type = {
	.owner =	THIS_MODULE,
	.name =		"securityfs",
	.mount =	get_sb,
	.kill_sb =	kill_litter_super,
};

/**
 * securityfs_create_dentry - create a dentry in the securityfs filesystem
 *
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the securityfs filesystem.
 * @data: a pointer to something that the caller will want to get to later
 *        on.  The inode.i_private pointer will point to this value on
 *        the open() call.
 * @fops: a pointer to a struct file_operations that should be used for
 *        this file.
 * @iops: a point to a struct of inode_operations that should be used for
 *        this file/dir
 *
 * This is the basic "create a file/dir/symlink" function for
 * securityfs.  It allows for a wide range of flexibility in creating
 * a file, or a directory (if you want to create a directory, the
 * securityfs_create_dir() function is recommended to be used
 * instead).
 *
 * This function returns a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the securityfs_remove() function when the
 * file is to be removed (no automatic cleanup happens if your module
 * is unloaded, you are responsible here).  If an error occurs, the
 * function will return the error value (via ERR_PTR).
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.
 */
static struct dentry *securityfs_create_dentry(const char *name, umode_t mode,
					struct dentry *parent, void *data,
					const struct file_operations *fops,
					const struct inode_operations *iops)
{
	struct dentry *dentry;
	struct inode *dir, *inode;
	int error;

	if (!(mode & S_IFMT))
		mode = (mode & S_IALLUGO) | S_IFREG;

	pr_debug("securityfs: creating file '%s'\n",name);

	error = simple_pin_fs(&fs_type, &mount, &mount_count);
	if (error)
		return ERR_PTR(error);

	if (!parent)
		parent = mount->mnt_root;

	dir = d_inode(parent);

	inode_lock(dir);
	dentry = lookup_one_len(name, parent, strlen(name));
	if (IS_ERR(dentry))
		goto out;

	if (d_really_is_positive(dentry)) {
		error = -EEXIST;
		goto out1;
	}

	inode = new_inode(dir->i_sb);
	if (!inode) {
		error = -ENOMEM;
		goto out1;
	}

	inode->i_ino = get_next_ino();
	inode->i_mode = mode;
	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
	inode->i_private = data;
	if (S_ISDIR(mode)) {
		inode->i_op = &simple_dir_inode_operations;
		inode->i_fop = &simple_dir_operations;
		inc_nlink(inode);
		inc_nlink(dir);
	} else if (S_ISLNK(mode)) {
		inode->i_op = iops ? iops : &simple_symlink_inode_operations;
		inode->i_link = data;
	} else {
		inode->i_fop = fops;
	}
	d_instantiate(dentry, inode);
	dget(dentry);
	inode_unlock(dir);
	return dentry;

out1:
	dput(dentry);
	dentry = ERR_PTR(error);
out:
	inode_unlock(dir);
	simple_release_fs(&mount, &mount_count);
	return dentry;
}

/**
 * securityfs_create_file - create a file in the securityfs filesystem
 *
 * @name: a pointer to a string containing the name of the file to create.
 * @mode: the permission that the file should have
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          file will be created in the root of the securityfs filesystem.
 * @data: a pointer to something that the caller will want to get to later
 *        on.  The inode.i_private pointer will point to this value on
 *        the open() call.
 * @fops: a pointer to a struct file_operations that should be used for
 *        this file.
 *
 * This function creates a file in securityfs with the given @name.
 *
 * This function returns a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the securityfs_remove() function when the file is
 * to be removed (no automatic cleanup happens if your module is unloaded,
 * you are responsible here).  If an error occurs, the function will return
 * the error value (via ERR_PTR).
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.
 */
struct dentry *securityfs_create_file(const char *name, umode_t mode,
				      struct dentry *parent, void *data,
				      const struct file_operations *fops)
{
	return securityfs_create_dentry(name, mode, parent, data, fops, NULL);
}
EXPORT_SYMBOL_GPL(securityfs_create_file);

/**
 * securityfs_create_dir - create a directory in the securityfs filesystem
 *
 * @name: a pointer to a string containing the name of the directory to
 *        create.
 * @parent: a pointer to the parent dentry for this file.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          directory will be created in the root of the securityfs filesystem.
 *
 * This function creates a directory in securityfs with the given @name.
 *
 * This function returns a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the securityfs_remove() function when the file is
 * to be removed (no automatic cleanup happens if your module is unloaded,
 * you are responsible here).  If an error occurs, the function will return
 * the error value (via ERR_PTR).
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.
 */
struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
{
	return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL);
}
EXPORT_SYMBOL_GPL(securityfs_create_dir);

/**
 * securityfs_create_symlink - create a symlink in the securityfs filesystem
 *
 * @name: a pointer to a string containing the name of the symlink to
 *        create.
 * @parent: a pointer to the parent dentry for the symlink.  This should be a
 *          directory dentry if set.  If this parameter is %NULL, then the
 *          directory will be created in the root of the securityfs filesystem.
 * @target: a pointer to a string containing the name of the symlink's target.
 *          If this parameter is %NULL, then the @iops parameter needs to be
 *          setup to handle .readlink and .get_link inode_operations.
 * @iops: a pointer to the struct inode_operations to use for the symlink. If
 *        this parameter is %NULL, then the default simple_symlink_inode
 *        operations will be used.
 *
 * This function creates a symlink in securityfs with the given @name.
 *
 * This function returns a pointer to a dentry if it succeeds.  This
 * pointer must be passed to the securityfs_remove() function when the file is
 * to be removed (no automatic cleanup happens if your module is unloaded,
 * you are responsible here).  If an error occurs, the function will return
 * the error value (via ERR_PTR).
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.
 */
struct dentry *securityfs_create_symlink(const char *name,
					 struct dentry *parent,
					 const char *target,
					 const struct inode_operations *iops)
{
	struct dentry *dent;
	char *link = NULL;

	if (target) {
		link = kstrdup(target, GFP_KERNEL);
		if (!link)
			return ERR_PTR(-ENOMEM);
	}
	dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent,
					link, NULL, iops);
	if (IS_ERR(dent))
		kfree(link);

	return dent;
}
EXPORT_SYMBOL_GPL(securityfs_create_symlink);

/**
 * securityfs_remove - removes a file or directory from the securityfs filesystem
 *
 * @dentry: a pointer to a the dentry of the file or directory to be removed.
 *
 * This function removes a file or directory in securityfs that was previously
 * created with a call to another securityfs function (like
 * securityfs_create_file() or variants thereof.)
 *
 * This function is required to be called in order for the file to be
 * removed. No automatic cleanup of files will happen when a module is
 * removed; you are responsible here.
 */
void securityfs_remove(struct dentry *dentry)
{
	struct inode *dir;

	if (!dentry || IS_ERR(dentry))
		return;

	dir = d_inode(dentry->d_parent);
	inode_lock(dir);
	if (simple_positive(dentry)) {
		if (d_is_dir(dentry))
			simple_rmdir(dir, dentry);
		else
			simple_unlink(dir, dentry);
		dput(dentry);
	}
	inode_unlock(dir);
	simple_release_fs(&mount, &mount_count);
}
EXPORT_SYMBOL_GPL(securityfs_remove);

#ifdef CONFIG_SECURITY
static struct dentry *lsm_dentry;
static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,
			loff_t *ppos)
{
	return simple_read_from_buffer(buf, count, ppos, lsm_names,
		strlen(lsm_names));
}

static const struct file_operations lsm_ops = {
	.read = lsm_read,
	.llseek = generic_file_llseek,
};
#endif

static int __init securityfs_init(void)
{
	int retval;

	retval = sysfs_create_mount_point(kernel_kobj, "security");
	if (retval)
		return retval;

	retval = register_filesystem(&fs_type);
	if (retval) {
		sysfs_remove_mount_point(kernel_kobj, "security");
		return retval;
	}
#ifdef CONFIG_SECURITY
	lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL,
						&lsm_ops);
#endif
	return 0;
}

core_initcall(securityfs_init);
MODULE_LICENSE("GPL");

OpenPOWER on IntegriCloud