path: root/fs/ecryptfs/inode.c

/**
 * eCryptfs: Linux filesystem encryption layer
 *
 * Copyright (C) 1997-2004 Erez Zadok
 * Copyright (C) 2001-2004 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
 *              Michael C. Thompsion <mcthomps@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/file.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/crypto.h>
#include <linux/fs_stack.h>
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"

static struct dentry *lock_parent(struct dentry *dentry)
{
	struct dentry *dir;

	dir = dget_parent(dentry);
	mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
	return dir;
}

static void unlock_dir(struct dentry *dir)
{
	mutex_unlock(&dir->d_inode->i_mutex);
	dput(dir);
}

/**
 * ecryptfs_create_underlying_file
 * @lower_dir_inode: inode of the parent in the lower fs of the new file
 * @dentry: New file's dentry
 * @mode: The mode of the new file
 * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
 *
 * Creates the file in the lower file system.
 *
 * Returns zero on success; non-zero on error condition
 */
static int
ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
				struct dentry *dentry, int mode,
				struct nameidata *nd)
{
	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
	struct dentry *dentry_save;
	struct vfsmount *vfsmount_save;
	int rc;

	dentry_save = nd->path.dentry;
	vfsmount_save = nd->path.mnt;
	nd->path.dentry = lower_dentry;
	nd->path.mnt = lower_mnt;
	rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
	nd->path.dentry = dentry_save;
	nd->path.mnt = vfsmount_save;
	return rc;
}

/**
 * ecryptfs_do_create
 * @directory_inode: inode of the new file's dentry's parent in ecryptfs
 * @ecryptfs_dentry: New file's dentry in ecryptfs
 * @mode: The mode of the new file
 * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
 *
 * Creates the underlying file and the eCryptfs inode which will link to
 * it. It will also update the eCryptfs directory inode to mimic the
 * stat of the lower directory inode.
 *
 * Returns zero on success; non-zero on error condition
 */
static int
ecryptfs_do_create(struct inode *directory_inode,
		   struct dentry *ecryptfs_dentry, int mode,
		   struct nameidata *nd)
{
	int rc;
	struct dentry *lower_dentry;
	struct dentry *lower_dir_dentry;

	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
	lower_dir_dentry = lock_parent(lower_dentry);
	if (IS_ERR(lower_dir_dentry)) {
		ecryptfs_printk(KERN_ERR, "Error locking directory of "
				"dentry\n");
		rc = PTR_ERR(lower_dir_dentry);
		goto out;
	}
	rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
					     ecryptfs_dentry, mode, nd);
	if (rc) {
		printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
		       "rc = [%d]\n", __func__, rc);
		goto out_lock;
	}
	rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
				directory_inode->i_sb, 0);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
		goto out_lock;
	}
	fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
	fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
out_lock:
	unlock_dir(lower_dir_dentry);
out:
	return rc;
}

/**
 * grow_file
 * @ecryptfs_dentry: the eCryptfs dentry
 *
 * This is the code which will grow the file to its correct size.
 */
static int grow_file(struct dentry *ecryptfs_dentry)
{
	struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
	struct file fake_file;
	struct ecryptfs_file_info tmp_file_info;
	char zero_virt[] = { 0x00 };
	int rc = 0;

	memset(&fake_file,