[linux-2.6-block.git] / security / inode.c

/*
 *  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/magic.h>

static struct vfsmount *mount;
static int mount_count;

/*
 * TODO:
 *   I think I can get rid of these default_file_ops, but not quite sure...
 */
static ssize_t default_read_file(struct file *file, char __user *buf,
				 size_t count, loff_t *ppos)
{
	return 0;
}

static ssize_t default_write_file(struct file *file, const char __user *buf,
				   size_t count, loff_t *ppos)
{
	return count;
}

static int default_open(struct inode *inode, struct file *file)
{
	if (inode->i_private)
		file->private_data = inode->i_private;

	return 0;
}

static const struct file_operations default_file_ops = {
	.read =		default_read_file,
	.write =	default_write_file,
	.open =		default_open,
};

static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev)
{
	struct inode *inode = new_inode(sb);

	if (inode) {
		inode->i_mode = mode;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
		switch (mode & S_IFMT) {
		default:
			init_special_inode(inode, mode, dev);
			break;
		case S_IFREG:
			inode->i_fop = &default_file_ops;
			break;
		case S_IFDIR:
			inode->i_op = &simple_dir_inode_operations;
			inode->i_fop = &simple_dir_operations;

			/* directory inodes start off with i_nlink == 2 (for "." entry) */
			inc_nlink(inode);
			break;
		}
	}
	return inode;
}

/* SMP-safe */
static int mknod(struct inode *dir, struct dentry *dentry,
			 int mode, dev_t dev)
{
	struct inode *inode;
	int error = -EPERM;

	if (dentry->d_inode)
		return -EEXIST;

	inode = get_inode(dir->i_sb, mode, dev);
	if (inode) {
		d_instantiate(dentry, inode);
		dget(dentry);
		error = 0;
	}
	return error;
}

static int mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int res;

	mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR;
	res = mknod(dir, dentry, mode, 0);
	if (!res)
		inc_nlink(dir);
	return res;
}

static int create(struct inode *dir, struct dentry *dentry, int mode)
{
	mode = (mode & S_IALLUGO) | S_IFREG;
	return mknod(dir, dentry, mode, 0);
}

static inline int positive(struct dentry *dentry)
{
	return dentry->d_inode && !d_unhashed(dentry);
}

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

	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
}

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

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

static int create_by_name(const char *name, mode_t mode,
			  struct dentry *parent,
			  struct dentry **dentry)
{
	int error = 0;

	*dentry = NULL;

	/* If the parent is not specified, we create it in the root.
	 * We need the root dentry to do this, which is in the super
	 * block. A pointer to that is in the struct vfsmount that we
	 * have around.
	 */
	if (!parent ) {
		if (mount && mount->mnt_sb) {
			parent = mount->mnt_sb->s_root;
		}
	}
	if (!parent) {
		pr_debug("securityfs: Ah! can not find a parent!\n");
		return -EFAULT;
	}

	mutex_lock(&parent->d_inode->i_mutex);
	*dentry = lookup_one_len(name, parent, strlen(name));
	if (!IS_ERR(dentry)) {
		if ((mode & S_IFMT) == S_IFDIR)
			error = mkdir(parent->d_inode, *dentry, mode);
		else
			error = create(parent->d_inode, *dentry, mode);
	} else
		error = PTR_ERR(dentry);
	mutex_unlock(&parent->d_inode->i_mutex);

	return error;
}

/**
 * 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 is the basic "create a file" 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, %NULL is returned.
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.  It is not wise to check for this value, but rather, check for
 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 * code.
 */
struct dentry *securityfs_create_file(const char *name, mode_t mode,
				   struct dentry *parent, void *data,
				   const struct file_operations *fops)
{
	struct dentry *dentry = NULL;
	int error;

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

	error = simple_pin_fs(&fs_type, &mount, &mount_count);
	if (error) {
		dentry = ERR_PTR(error);
		goto exit;
	}

	error = create_by_name(name, mode, parent, &dentry);
	if (error) {
		dentry = ERR_PTR(error);
		simple_release_fs(&mount, &mount_count);
		goto exit;
	}

	if (dentry->d_inode) {
		if (fops)
			dentry->d_inode->i_fop = fops;
		if (data)
			dentry->d_inode->i_private = data;
	}
exit:
	return dentry;
}
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, %NULL will be returned.
 *
 * If securityfs is not enabled in the kernel, the value %-ENODEV is
 * returned.  It is not wise to check for this value, but rather, check for
 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 * code.
 */
struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
{
	return securityfs_create_file(name,
				      S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
				      parent, NULL, NULL);
}
EXPORT_SYMBOL_GPL(securityfs_create_dir);

/**
 * 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 dentry *parent;

	if (!dentry)
		return;

	parent = dentry->d_parent;
	if (!parent || !parent->d_inode)
		return;

	mutex_lock(&parent->d_inode->i_mutex);
	if (positive(dentry)) {
		if (dentry->d_inode) {
			if (S_ISDIR(dentry->d_inode->i_mode))
				simple_rmdir(parent->d_inode, dentry);
			else
				simple_unlink(parent->d_inode, dentry);
			dput(dentry);
		}
	}
	mutex_unlock(&parent->d_inode->i_mutex);
	simple_release_fs(&mount, &mount_count);
}
EXPORT_SYMBOL_GPL(securityfs_remove);

static struct kobject *security_kobj;

static int __init securityfs_init(void)
{
	int retval;

	security_kobj = kobject_create_and_add("security", kernel_kobj);
	if (!security_kobj)
		return -EINVAL;

	retval = register_filesystem(&fs_type);
	if (retval)
		kobject_put(security_kobj);
	return retval;
}

core_initcall(securityfs_init);
MODULE_LICENSE("GPL");
Commit	Line	Data
b67dbf9d GK	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 */
b67dbf9d GK	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>
92562927	23	#include <linux/magic.h>
b67dbf9d GK	24
	25	static struct vfsmount *mount;
	26	static int mount_count;
	27
	28	/*
	29	* TODO:
	30	* I think I can get rid of these default_file_ops, but not quite sure...
	31	*/
	32	static ssize_t default_read_file(struct file file, char __user buf,
	33	size_t count, loff_t *ppos)
	34	{
	35	return 0;
	36	}
	37
	38	static ssize_t default_write_file(struct file file, const char __user buf,
	39	size_t count, loff_t *ppos)
	40	{
	41	return count;
	42	}
	43
	44	static int default_open(struct inode inode, struct file file)
	45	{
8e18e294 TT	46	if (inode->i_private)
8e18e294 TT	47	file->private_data = inode->i_private;
b67dbf9d GK	48
	49	return 0;
	50	}
	51
9c2e08c5	52	static const struct file_operations default_file_ops = {
b67dbf9d GK	53	.read = default_read_file,
	54	.write = default_write_file,
	55	.open = default_open,
	56	};
	57
	58	static struct inode get_inode(struct super_block sb, int mode, dev_t dev)
	59	{
	60	struct inode *inode = new_inode(sb);
	61
	62	if (inode) {
	63	inode->i_mode = mode;
b67dbf9d GK	64	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	65	switch (mode & S_IFMT) {
	66	default:
	67	init_special_inode(inode, mode, dev);
	68	break;
	69	case S_IFREG:
	70	inode->i_fop = &default_file_ops;
	71	break;
	72	case S_IFDIR:
	73	inode->i_op = &simple_dir_inode_operations;
	74	inode->i_fop = &simple_dir_operations;
	75
	76	/* directory inodes start off with i_nlink == 2 (for "." entry) */
d8c76e6f	77	inc_nlink(inode);
b67dbf9d GK	78	break;
	79	}
	80	}
	81	return inode;
	82	}
	83
	84	/* SMP-safe */
	85	static int mknod(struct inode dir, struct dentry dentry,
	86	int mode, dev_t dev)
	87	{
	88	struct inode *inode;
	89	int error = -EPERM;
	90
	91	if (dentry->d_inode)
	92	return -EEXIST;
	93
	94	inode = get_inode(dir->i_sb, mode, dev);
	95	if (inode) {
	96	d_instantiate(dentry, inode);
	97	dget(dentry);
	98	error = 0;
	99	}
	100	return error;
	101	}
	102
	103	static int mkdir(struct inode dir, struct dentry dentry, int mode)
	104	{
	105	int res;
	106
	107	mode = (mode & (S_IRWXUGO \| S_ISVTX)) \| S_IFDIR;
	108	res = mknod(dir, dentry, mode, 0);
	109	if (!res)
d8c76e6f	110	inc_nlink(dir);
b67dbf9d GK	111	return res;
	112	}
	113
	114	static int create(struct inode dir, struct dentry dentry, int mode)
	115	{
	116	mode = (mode & S_IALLUGO) \| S_IFREG;
	117	return mknod(dir, dentry, mode, 0);
	118	}
	119
	120	static inline int positive(struct dentry *dentry)
	121	{
	122	return dentry->d_inode && !d_unhashed(dentry);
	123	}
	124
	125	static int fill_super(struct super_block sb, void data, int silent)
	126	{
	127	static struct tree_descr files[] = {{""}};
	128
	129	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
	130	}
	131
454e2398 DH	132	static int get_sb(struct file_system_type *fs_type,
	133	int flags, const char *dev_name,
	134	void data, struct vfsmount mnt)
b67dbf9d	135	{
454e2398	136	return get_sb_single(fs_type, flags, data, fill_super, mnt);
b67dbf9d GK	137	}
	138
	139	static struct file_system_type fs_type = {
	140	.owner = THIS_MODULE,
	141	.name = "securityfs",
	142	.get_sb = get_sb,
	143	.kill_sb = kill_litter_super,
	144	};
	145
	146	static int create_by_name(const char *name, mode_t mode,
	147	struct dentry *parent,
	148	struct dentry **dentry)
	149	{
	150	int error = 0;
	151
	152	*dentry = NULL;
	153
	154	/* If the parent is not specified, we create it in the root.
	155	* We need the root dentry to do this, which is in the super
	156	* block. A pointer to that is in the struct vfsmount that we
	157	* have around.
	158	*/
	159	if (!parent ) {
	160	if (mount && mount->mnt_sb) {
	161	parent = mount->mnt_sb->s_root;
	162	}
	163	}
	164	if (!parent) {
	165	pr_debug("securityfs: Ah! can not find a parent!\n");
	166	return -EFAULT;
	167	}
	168
1b1dcc1b	169	mutex_lock(&parent->d_inode->i_mutex);
b67dbf9d GK	170	*dentry = lookup_one_len(name, parent, strlen(name));
	171	if (!IS_ERR(dentry)) {
	172	if ((mode & S_IFMT) == S_IFDIR)
	173	error = mkdir(parent->d_inode, *dentry, mode);
	174	else
	175	error = create(parent->d_inode, *dentry, mode);
	176	} else
	177	error = PTR_ERR(dentry);
1b1dcc1b	178	mutex_unlock(&parent->d_inode->i_mutex);
b67dbf9d GK	179
	180	return error;
	181	}
	182
	183	/**
	184	* securityfs_create_file - create a file in the securityfs filesystem
	185	*
	186	* @name: a pointer to a string containing the name of the file to create.
	187	* @mode: the permission that the file should have
	188	* @parent: a pointer to the parent dentry for this file. This should be a
3f23d815	189	* directory dentry if set. If this parameter is %NULL, then the
b67dbf9d GK	190	* file will be created in the root of the securityfs filesystem.
b67dbf9d GK	191	* @data: a pointer to something that the caller will want to get to later
8e18e294	192	* on. The inode.i_private pointer will point to this value on
b67dbf9d GK	193	* the open() call.
	194	* @fops: a pointer to a struct file_operations that should be used for
	195	* this file.
	196	*
	197	* This is the basic "create a file" function for securityfs. It allows for a
3f23d815	198	* wide range of flexibility in creating a file, or a directory (if you
b67dbf9d	199	* want to create a directory, the securityfs_create_dir() function is
3f23d815	200	* recommended to be used instead).
b67dbf9d	201	*
3f23d815	202	* This function returns a pointer to a dentry if it succeeds. This
b67dbf9d GK	203	* pointer must be passed to the securityfs_remove() function when the file is
b67dbf9d GK	204	* to be removed (no automatic cleanup happens if your module is unloaded,
3f23d815	205	* you are responsible here). If an error occurs, %NULL is returned.
b67dbf9d	206	*
3f23d815	207	* If securityfs is not enabled in the kernel, the value %-ENODEV is
b67dbf9d	208	* returned. It is not wise to check for this value, but rather, check for
3f23d815	209	* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
b67dbf9d GK	210	* code.
	211	*/
	212	struct dentry securityfs_create_file(const char name, mode_t mode,
	213	struct dentry parent, void data,
9c2e08c5	214	const struct file_operations *fops)
b67dbf9d GK	215	{
	216	struct dentry *dentry = NULL;
	217	int error;
	218
	219	pr_debug("securityfs: creating file '%s'\n",name);
	220
1f5ce9e9	221	error = simple_pin_fs(&fs_type, &mount, &mount_count);
b67dbf9d GK	222	if (error) {
	223	dentry = ERR_PTR(error);
	224	goto exit;
	225	}
	226
	227	error = create_by_name(name, mode, parent, &dentry);
	228	if (error) {
	229	dentry = ERR_PTR(error);
	230	simple_release_fs(&mount, &mount_count);
	231	goto exit;
	232	}
	233
	234	if (dentry->d_inode) {
	235	if (fops)
	236	dentry->d_inode->i_fop = fops;
	237	if (data)
8e18e294	238	dentry->d_inode->i_private = data;
b67dbf9d GK	239	}
	240	exit:
	241	return dentry;
	242	}
	243	EXPORT_SYMBOL_GPL(securityfs_create_file);
	244
	245	/**
	246	* securityfs_create_dir - create a directory in the securityfs filesystem
	247	*
	248	* @name: a pointer to a string containing the name of the directory to
	249	* create.
	250	* @parent: a pointer to the parent dentry for this file. This should be a
3f23d815	251	* directory dentry if set. If this parameter is %NULL, then the
b67dbf9d GK	252	* directory will be created in the root of the securityfs filesystem.
b67dbf9d GK	253	*
3f23d815	254	* This function creates a directory in securityfs with the given @name.
b67dbf9d	255	*
3f23d815	256	* This function returns a pointer to a dentry if it succeeds. This
b67dbf9d GK	257	* pointer must be passed to the securityfs_remove() function when the file is
b67dbf9d GK	258	* to be removed (no automatic cleanup happens if your module is unloaded,
3f23d815	259	* you are responsible here). If an error occurs, %NULL will be returned.
b67dbf9d	260	*
3f23d815	261	* If securityfs is not enabled in the kernel, the value %-ENODEV is
b67dbf9d	262	* returned. It is not wise to check for this value, but rather, check for
3f23d815	263	* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
b67dbf9d GK	264	* code.
	265	*/
	266	struct dentry securityfs_create_dir(const char name, struct dentry *parent)
	267	{
	268	return securityfs_create_file(name,
	269	S_IFDIR \| S_IRWXU \| S_IRUGO \| S_IXUGO,
	270	parent, NULL, NULL);
	271	}
	272	EXPORT_SYMBOL_GPL(securityfs_create_dir);
	273
	274	/**
	275	* securityfs_remove - removes a file or directory from the securityfs filesystem
	276	*
3f23d815	277	* @dentry: a pointer to a the dentry of the file or directory to be removed.
b67dbf9d GK	278	*
	279	* This function removes a file or directory in securityfs that was previously
	280	* created with a call to another securityfs function (like
	281	* securityfs_create_file() or variants thereof.)
	282	*
	283	* This function is required to be called in order for the file to be
3f23d815 RD	284	* removed. No automatic cleanup of files will happen when a module is
3f23d815 RD	285	* removed; you are responsible here.
b67dbf9d GK	286	*/
	287	void securityfs_remove(struct dentry *dentry)
	288	{
	289	struct dentry *parent;
	290
	291	if (!dentry)
	292	return;
	293
	294	parent = dentry->d_parent;
	295	if (!parent \|\| !parent->d_inode)
	296	return;
	297
1b1dcc1b	298	mutex_lock(&parent->d_inode->i_mutex);
b67dbf9d GK	299	if (positive(dentry)) {
	300	if (dentry->d_inode) {
	301	if (S_ISDIR(dentry->d_inode->i_mode))
	302	simple_rmdir(parent->d_inode, dentry);
	303	else
	304	simple_unlink(parent->d_inode, dentry);
	305	dput(dentry);
	306	}
	307	}
1b1dcc1b	308	mutex_unlock(&parent->d_inode->i_mutex);
b67dbf9d GK	309	simple_release_fs(&mount, &mount_count);
	310	}
	311	EXPORT_SYMBOL_GPL(securityfs_remove);
	312
69d8e138	313	static struct kobject *security_kobj;
b67dbf9d GK	314
	315	static int __init securityfs_init(void)
	316	{
	317	int retval;
	318
0ff21e46	319	security_kobj = kobject_create_and_add("security", kernel_kobj);
69d8e138 GKH	320	if (!security_kobj)
69d8e138 GKH	321	return -EINVAL;
b67dbf9d GK	322
	323	retval = register_filesystem(&fs_type);
	324	if (retval)
78a2d906	325	kobject_put(security_kobj);
b67dbf9d GK	326	return retval;
	327	}
	328
b67dbf9d	329	core_initcall(securityfs_init);
b67dbf9d GK	330	MODULE_LICENSE("GPL");
b67dbf9d GK	331