342 lines
10 KiB
C
342 lines
10 KiB
C
// 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/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 fill_super(struct super_block *sb, void *data, int silent)
|
|
{
|
|
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 struct dentry *get_sb(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name,
|
|
void *data)
|
|
{
|
|
return mount_single(fs_type, flags, data, fill_super);
|
|
}
|
|
|
|
static struct file_system_type fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "securityfs",
|
|
.mount = get_sb,
|
|
.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_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);
|