// 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)
{
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);
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