linux/security/inode.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  inode.c - securityfs
 *
 *  Copyright (C) 2005 Greg Kroah-Hartman <[email protected]>
 *
 *  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/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)
{ … }

static const struct super_operations securityfs_super_operations = …;

static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
{ … }

static int securityfs_get_tree(struct fs_context *fc)
{ … }

static const struct fs_context_operations securityfs_context_ops = …;

static int securityfs_init_fs_context(struct fs_context *fc)
{ … }

static struct file_system_type fs_type = …;

/**
 * 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)
{ … }

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

#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)
{ … }

static const struct file_operations lsm_ops = …;
#endif

static int __init securityfs_init(void)
{ … }
core_initcall(securityfs_init);