// SPDX-License-Identifier: GPL-2.0-only/* *  inode.c - securityfs * *  Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> * *  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/sysfs.h>#include <linux/kobject.h>#include <linux/fs.h>#include <linux/fs_context.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_free_inode(struct inode *inode){	if (S_ISLNK(inode->i_mode))		kfree(inode->i_link);	free_inode_nonrcu(inode);} static const struct super_operations securityfs_super_operations = {	.statfs		= simple_statfs,	.free_inode	= securityfs_free_inode,}; static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc){	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 int securityfs_get_tree(struct fs_context *fc){	return get_tree_single(fc, securityfs_fill_super);} static const struct fs_context_operations securityfs_context_ops = {	.get_tree	= securityfs_get_tree,}; static int securityfs_init_fs_context(struct fs_context *fc){	fc->ops = &securityfs_context_ops;	return 0;} static struct file_system_type fs_type = {	.owner =	THIS_MODULE,	.name =		"securityfs",	.init_fs_context = securityfs_init_fs_context,	.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_SECURITYstatic 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);