[linux.git] / security / inode.c

/*
 *  inode.c - securityfs
 *
 *  Copyright (C) 2005 Greg Kroah-Hartman <[email protected]>
 *
 *	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 <[email protected]>
 *    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>

#define SECURITYFS_MAGIC	0x73636673

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 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_uid = 0;
		inode->i_gid = 0;
		inode->i_blocks = 0;
		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 paramater 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 createing 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 will return 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 will be
 * 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,
				   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 paramater 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 will return 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 will be
 * 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 decl_subsys(security, NULL, NULL);

static int __init securityfs_init(void)
{
	int retval;

	kset_set_kset_s(&security_subsys, kernel_subsys);
	retval = subsystem_register(&security_subsys);
	if (retval)
		return retval;

	retval = register_filesystem(&fs_type);
	if (retval)
		subsystem_unregister(&security_subsys);
	return retval;
}

static void __exit securityfs_exit(void)
{
	simple_release_fs(&mount, &mount_count);
	unregister_filesystem(&fs_type);
	subsystem_unregister(&security_subsys);
}

core_initcall(securityfs_init);
module_exit(securityfs_exit);
MODULE_LICENSE("GPL");
Commit	Line	Data
b67dbf9d GKH	1	/*
	2	* inode.c - securityfs
	3	*
	4	* Copyright (C) 2005 Greg Kroah-Hartman <[email protected]>
	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 <[email protected]>
	12	* Copyright (C) 2004 IBM Inc.
	13	*/
	14
	15	/* #define DEBUG */
b67dbf9d GKH	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>
	23
	24	#define SECURITYFS_MAGIC 0x73636673
	25
	26	static struct vfsmount *mount;
	27	static int mount_count;
	28
	29	/*
	30	* TODO:
	31	* I think I can get rid of these default_file_ops, but not quite sure...
	32	*/
	33	static ssize_t default_read_file(struct file file, char __user buf,
	34	size_t count, loff_t *ppos)
	35	{
	36	return 0;
	37	}
	38
	39	static ssize_t default_write_file(struct file file, const char __user buf,
	40	size_t count, loff_t *ppos)
	41	{
	42	return count;
	43	}
	44
	45	static int default_open(struct inode inode, struct file file)
	46	{
8e18e294 TT	47	if (inode->i_private)
8e18e294 TT	48	file->private_data = inode->i_private;
b67dbf9d GKH	49
	50	return 0;
	51	}
	52
	53	static struct file_operations default_file_ops = {
	54	.read = default_read_file,
	55	.write = default_write_file,
	56	.open = default_open,
	57	};
	58
	59	static struct inode get_inode(struct super_block sb, int mode, dev_t dev)
	60	{
	61	struct inode *inode = new_inode(sb);
	62
	63	if (inode) {
	64	inode->i_mode = mode;
	65	inode->i_uid = 0;
	66	inode->i_gid = 0;
b67dbf9d GKH	67	inode->i_blocks = 0;
	68	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	69	switch (mode & S_IFMT) {
	70	default:
	71	init_special_inode(inode, mode, dev);
	72	break;
	73	case S_IFREG:
	74	inode->i_fop = &default_file_ops;
	75	break;
	76	case S_IFDIR:
	77	inode->i_op = &simple_dir_inode_operations;
	78	inode->i_fop = &simple_dir_operations;
	79
	80	/* directory inodes start off with i_nlink == 2 (for "." entry) */
d8c76e6f	81	inc_nlink(inode);
b67dbf9d GKH	82	break;
	83	}
	84	}
	85	return inode;
	86	}
	87
	88	/* SMP-safe */
	89	static int mknod(struct inode dir, struct dentry dentry,
	90	int mode, dev_t dev)
	91	{
	92	struct inode *inode;
	93	int error = -EPERM;
	94
	95	if (dentry->d_inode)
	96	return -EEXIST;
	97
	98	inode = get_inode(dir->i_sb, mode, dev);
	99	if (inode) {
	100	d_instantiate(dentry, inode);
	101	dget(dentry);
	102	error = 0;
	103	}
	104	return error;
	105	}
	106
	107	static int mkdir(struct inode dir, struct dentry dentry, int mode)
	108	{
	109	int res;
	110
	111	mode = (mode & (S_IRWXUGO \| S_ISVTX)) \| S_IFDIR;
	112	res = mknod(dir, dentry, mode, 0);
	113	if (!res)
d8c76e6f	114	inc_nlink(dir);
b67dbf9d GKH	115	return res;
	116	}
	117
	118	static int create(struct inode dir, struct dentry dentry, int mode)
	119	{
	120	mode = (mode & S_IALLUGO) \| S_IFREG;
	121	return mknod(dir, dentry, mode, 0);
	122	}
	123
	124	static inline int positive(struct dentry *dentry)
	125	{
	126	return dentry->d_inode && !d_unhashed(dentry);
	127	}
	128
	129	static int fill_super(struct super_block sb, void data, int silent)
	130	{
	131	static struct tree_descr files[] = {{""}};
	132
	133	return simple_fill_super(sb, SECURITYFS_MAGIC, files);
	134	}
	135
454e2398 DH	136	static int get_sb(struct file_system_type *fs_type,
	137	int flags, const char *dev_name,
	138	void data, struct vfsmount mnt)
b67dbf9d	139	{
454e2398	140	return get_sb_single(fs_type, flags, data, fill_super, mnt);
b67dbf9d GKH	141	}
	142
	143	static struct file_system_type fs_type = {
	144	.owner = THIS_MODULE,
	145	.name = "securityfs",
	146	.get_sb = get_sb,
	147	.kill_sb = kill_litter_super,
	148	};
	149
	150	static int create_by_name(const char *name, mode_t mode,
	151	struct dentry *parent,
	152	struct dentry **dentry)
	153	{
	154	int error = 0;
	155
	156	*dentry = NULL;
	157
	158	/* If the parent is not specified, we create it in the root.
	159	* We need the root dentry to do this, which is in the super
	160	* block. A pointer to that is in the struct vfsmount that we
	161	* have around.
	162	*/
	163	if (!parent ) {
	164	if (mount && mount->mnt_sb) {
	165	parent = mount->mnt_sb->s_root;
	166	}
	167	}
	168	if (!parent) {
	169	pr_debug("securityfs: Ah! can not find a parent!\n");
	170	return -EFAULT;
	171	}
	172
1b1dcc1b	173	mutex_lock(&parent->d_inode->i_mutex);
b67dbf9d GKH	174	*dentry = lookup_one_len(name, parent, strlen(name));
	175	if (!IS_ERR(dentry)) {
	176	if ((mode & S_IFMT) == S_IFDIR)
	177	error = mkdir(parent->d_inode, *dentry, mode);
	178	else
	179	error = create(parent->d_inode, *dentry, mode);
	180	} else
	181	error = PTR_ERR(dentry);
1b1dcc1b	182	mutex_unlock(&parent->d_inode->i_mutex);
b67dbf9d GKH	183
	184	return error;
	185	}
	186
	187	/**
	188	* securityfs_create_file - create a file in the securityfs filesystem
	189	*
	190	* @name: a pointer to a string containing the name of the file to create.
	191	* @mode: the permission that the file should have
	192	* @parent: a pointer to the parent dentry for this file. This should be a
	193	* directory dentry if set. If this paramater is NULL, then the
	194	* file will be created in the root of the securityfs filesystem.
	195	* @data: a pointer to something that the caller will want to get to later
8e18e294	196	* on. The inode.i_private pointer will point to this value on
b67dbf9d GKH	197	* the open() call.
	198	* @fops: a pointer to a struct file_operations that should be used for
	199	* this file.
	200	*
	201	* This is the basic "create a file" function for securityfs. It allows for a
	202	* wide range of flexibility in createing a file, or a directory (if you
	203	* want to create a directory, the securityfs_create_dir() function is
	204	* recommended to be used instead.)
	205	*
	206	* This function will return a pointer to a dentry if it succeeds. This
	207	* pointer must be passed to the securityfs_remove() function when the file is
	208	* to be removed (no automatic cleanup happens if your module is unloaded,
	209	* you are responsible here.) If an error occurs, NULL will be returned.
	210	*
	211	* If securityfs is not enabled in the kernel, the value -ENODEV will be
	212	* returned. It is not wise to check for this value, but rather, check for
	213	* NULL or !NULL instead as to eliminate the need for #ifdef in the calling
	214	* code.
	215	*/
	216	struct dentry securityfs_create_file(const char name, mode_t mode,
	217	struct dentry parent, void data,
	218	struct file_operations *fops)
	219	{
	220	struct dentry *dentry = NULL;
	221	int error;
	222
	223	pr_debug("securityfs: creating file '%s'\n",name);
	224
1f5ce9e9	225	error = simple_pin_fs(&fs_type, &mount, &mount_count);
b67dbf9d GKH	226	if (error) {
	227	dentry = ERR_PTR(error);
	228	goto exit;
	229	}
	230
	231	error = create_by_name(name, mode, parent, &dentry);
	232	if (error) {
	233	dentry = ERR_PTR(error);
	234	simple_release_fs(&mount, &mount_count);
	235	goto exit;
	236	}
	237
	238	if (dentry->d_inode) {
	239	if (fops)
	240	dentry->d_inode->i_fop = fops;
	241	if (data)
8e18e294	242	dentry->d_inode->i_private = data;
b67dbf9d GKH	243	}
	244	exit:
	245	return dentry;
	246	}
	247	EXPORT_SYMBOL_GPL(securityfs_create_file);
	248
	249	/**
	250	* securityfs_create_dir - create a directory in the securityfs filesystem
	251	*
	252	* @name: a pointer to a string containing the name of the directory to
	253	* create.
	254	* @parent: a pointer to the parent dentry for this file. This should be a
	255	* directory dentry if set. If this paramater is NULL, then the
	256	* directory will be created in the root of the securityfs filesystem.
	257	*
	258	* This function creates a directory in securityfs with the given name.
	259	*
	260	* This function will return a pointer to a dentry if it succeeds. This
	261	* pointer must be passed to the securityfs_remove() function when the file is
	262	* to be removed (no automatic cleanup happens if your module is unloaded,
	263	* you are responsible here.) If an error occurs, NULL will be returned.
	264	*
	265	* If securityfs is not enabled in the kernel, the value -ENODEV will be
	266	* returned. It is not wise to check for this value, but rather, check for
	267	* NULL or !NULL instead as to eliminate the need for #ifdef in the calling
	268	* code.
	269	*/
	270	struct dentry securityfs_create_dir(const char name, struct dentry *parent)
	271	{
	272	return securityfs_create_file(name,
	273	S_IFDIR \| S_IRWXU \| S_IRUGO \| S_IXUGO,
	274	parent, NULL, NULL);
	275	}
	276	EXPORT_SYMBOL_GPL(securityfs_create_dir);
	277
	278	/**
	279	* securityfs_remove - removes a file or directory from the securityfs filesystem
	280	*
	281	* @dentry: a pointer to a the dentry of the file or directory to be
	282	* removed.
	283	*
	284	* This function removes a file or directory in securityfs that was previously
	285	* created with a call to another securityfs function (like
	286	* securityfs_create_file() or variants thereof.)
	287	*
	288	* This function is required to be called in order for the file to be
	289	* removed, no automatic cleanup of files will happen when a module is
	290	* removed, you are responsible here.
	291	*/
	292	void securityfs_remove(struct dentry *dentry)
	293	{
	294	struct dentry *parent;
	295
	296	if (!dentry)
	297	return;
	298
	299	parent = dentry->d_parent;
	300	if (!parent \|\| !parent->d_inode)
	301	return;
	302
1b1dcc1b	303	mutex_lock(&parent->d_inode->i_mutex);
b67dbf9d GKH	304	if (positive(dentry)) {
	305	if (dentry->d_inode) {
	306	if (S_ISDIR(dentry->d_inode->i_mode))
	307	simple_rmdir(parent->d_inode, dentry);
	308	else
	309	simple_unlink(parent->d_inode, dentry);
	310	dput(dentry);
	311	}
	312	}
1b1dcc1b	313	mutex_unlock(&parent->d_inode->i_mutex);
b67dbf9d GKH	314	simple_release_fs(&mount, &mount_count);
	315	}
	316	EXPORT_SYMBOL_GPL(securityfs_remove);
	317
	318	static decl_subsys(security, NULL, NULL);
	319
	320	static int __init securityfs_init(void)
	321	{
	322	int retval;
	323
	324	kset_set_kset_s(&security_subsys, kernel_subsys);
	325	retval = subsystem_register(&security_subsys);
	326	if (retval)
	327	return retval;
	328
	329	retval = register_filesystem(&fs_type);
	330	if (retval)
	331	subsystem_unregister(&security_subsys);
	332	return retval;
	333	}
	334
	335	static void __exit securityfs_exit(void)
	336	{
	337	simple_release_fs(&mount, &mount_count);
	338	unregister_filesystem(&fs_type);
	339	subsystem_unregister(&security_subsys);
	340	}
	341
	342	core_initcall(securityfs_init);
	343	module_exit(securityfs_exit);
	344	MODULE_LICENSE("GPL");
	345