// 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> #include "lsm.h" static struct vfsmount *mount;static int mount_count; static void securityfs_free_inode(struct inode *inode){	if (S_ISLNK(inode->i_mode))		kfree_const(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_anon_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;	bool pinned = false; 	if (!(mode & S_IFMT))		mode = (mode & S_IALLUGO) | S_IFREG; 	pr_debug("securityfs: creating file '%s'\n",name); 	if (!parent) {		error = simple_pin_fs(&fs_type, &mount, &mount_count);		if (error)			return ERR_PTR(error);		pinned = true;		parent = mount->mnt_root;	} 	inode = new_inode(parent->d_sb);	if (unlikely(!inode)) {		dentry = ERR_PTR(-ENOMEM);		goto out;	} 	dir = d_inode(parent); 	dentry = simple_start_creating(parent, name);	if (IS_ERR(dentry)) {		iput(inode);		goto out;	}	inode->i_ino = get_next_ino();	inode->i_mode = mode;	simple_inode_init_ts(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_make_persistent(dentry, inode);	simple_done_creating(dentry);	return dentry; // borrowed out:	if (pinned)		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;	const char *link = NULL; 	if (target) {		link = kstrdup_const(target, GFP_KERNEL);		if (!link)			return ERR_PTR(-ENOMEM);	}	dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent,					(void *)link, NULL, iops);	if (IS_ERR(dent))		kfree_const(link); 	return dent;}EXPORT_SYMBOL_GPL(securityfs_create_symlink); static void remove_one(struct dentry *victim){	if (victim->d_parent == victim->d_sb->s_root)		simple_release_fs(&mount, &mount_count);} /** * 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. * * AV: when applied to directory it will take all children out; no need to call * it for descendents if ancestor is getting killed. */void securityfs_remove(struct dentry *dentry){	if (IS_ERR_OR_NULL(dentry))		return; 	simple_pin_fs(&fs_type, &mount, &mount_count);	simple_recursive_removal(dentry, remove_one);	simple_release_fs(&mount, &mount_count);}EXPORT_SYMBOL_GPL(securityfs_remove); #ifdef CONFIG_SECURITY#include <linux/spinlock.h> static struct dentry *lsm_dentry; static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count,			loff_t *ppos){	int i;	static char *str;	static size_t len;	static DEFINE_SPINLOCK(lock); 	/* NOTE: we never free or modify the string once it is set */ 	if (unlikely(!str || !len)) {		char *str_tmp;		size_t len_tmp = 0; 		for (i = 0; i < lsm_active_cnt; i++)			/* the '+ 1' accounts for either a comma or a NUL */			len_tmp += strlen(lsm_idlist[i]->name) + 1; 		str_tmp = kmalloc(len_tmp, GFP_KERNEL);		if (!str_tmp)			return -ENOMEM;		str_tmp[0] = '\0'; 		for (i = 0; i < lsm_active_cnt; i++) {			if (i > 0)				strcat(str_tmp, ",");			strcat(str_tmp, lsm_idlist[i]->name);		} 		spin_lock(&lock);		if (!str) {			str = str_tmp;			len = len_tmp - 1;		} else			kfree(str_tmp);		spin_unlock(&lock);	} 	return simple_read_from_buffer(buf, count, ppos, str, len);} static const struct file_operations lsm_ops = {	.read = lsm_read,	.llseek = generic_file_llseek,};#endif 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;}