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tag: v3.7-rc3
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/*
* inode.c - securityfs
*
* Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* 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/module.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/magic.h>

static struct vfsmount *mount;
static int mount_count;

static inline int positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}

static int fill_super(struct super_block *sb, void *data, int silent)
{
static struct tree_descr files[] = {{""}};

return simple_fill_super(sb, SECURITYFS_MAGIC, files);
}

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_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 is the basic "create a file" 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 erorr 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)
{
struct dentry *dentry;
int is_dir = S_ISDIR(mode);
struct inode *dir, *inode;
int error;

if (!is_dir) {
BUG_ON(!fops);
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 = parent->d_inode;

mutex_lock(&dir->i_mutex);
dentry = lookup_one_len(name, parent, strlen(name));
if (IS_ERR(dentry))
goto out;

if (dentry->d_inode) {
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->i_private = data;
if (is_dir) {
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
inc_nlink(inode);
inc_nlink(dir);
} else {
inode->i_fop = fops;
}
d_instantiate(dentry, inode);
dget(dentry);
mutex_unlock(&dir->i_mutex);
return dentry;

out1:
dput(dentry);
dentry = ERR_PTR(error);
out:
mutex_unlock(&dir->i_mutex);
simple_release_fs(&mount, &mount_count);
return dentry;
}
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, %NULL will be returned.
*
* If securityfs is not enabled in the kernel, the value %-ENODEV is
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
{
return securityfs_create_file(name,
S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
parent, NULL, NULL);
}
EXPORT_SYMBOL_GPL(securityfs_create_dir);

/**
* 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 dentry *parent;

if (!dentry || IS_ERR(dentry))
return;

parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;

mutex_lock(&parent->d_inode->i_mutex);
if (positive(dentry)) {
if (dentry->d_inode) {
if (S_ISDIR(dentry->d_inode->i_mode))
simple_rmdir(parent->d_inode, dentry);
else
simple_unlink(parent->d_inode, dentry);
dput(dentry);
}
}
mutex_unlock(&parent->d_inode->i_mutex);
simple_release_fs(&mount, &mount_count);
}
EXPORT_SYMBOL_GPL(securityfs_remove);

static struct kobject *security_kobj;

static int __init securityfs_init(void)
{
int retval;

security_kobj = kobject_create_and_add("security", kernel_kobj);
if (!security_kobj)
return -EINVAL;

retval = register_filesystem(&fs_type);
if (retval)
kobject_put(security_kobj);
return retval;
}

core_initcall(securityfs_init);
MODULE_LICENSE("GPL");

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