/* *  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/config.h>#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->u.generic_ip)		file->private_data = inode->u.generic_ip; 	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_blksize = PAGE_CACHE_SIZE;		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) */			inode->i_nlink++;			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)		dir->i_nlink++;	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 struct super_block *get_sb(struct file_system_type *fs_type,				        int flags, const char *dev_name,					void *data){	return get_sb_single(fs_type, flags, data, fill_super);} 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.u.generic_ip 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("securityfs", &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->u.generic_ip = 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");