security/inode.c - linux - Git at Google

 // 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;
 	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_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 (IS_ERR_OR_NULL(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);

 static void remove_one(struct dentry *victim)
 {
 	simple_release_fs(&mount, &mount_count);
 }

 /**
  * securityfs_recursive_remove - recursively removes a file or directory
  *
  * @dentry: a pointer to a the dentry of the file or directory to be removed.
  *
  * This function recursively 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.)
  */
 void securityfs_recursive_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_recursive_remove);

 #ifdef CONFIG_SECURITY
 static 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);
	// 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;
	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_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 (IS_ERR_OR_NULL(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);

	static void remove_one(struct dentry *victim)
	{
	simple_release_fs(&mount, &mount_count);
	}

	/**
	* securityfs_recursive_remove - recursively removes a file or directory
	*
	* @dentry: a pointer to a the dentry of the file or directory to be removed.
	*
	* This function recursively 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.)
	*/
	void securityfs_recursive_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_recursive_remove);

	#ifdef CONFIG_SECURITY
	static 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);