path: root/fs/ecryptfs/inode.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#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/fs_stack.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>
#include <linux/fileattr.h>
#include <linux/unaligned.h>
#include "ecryptfs_kernel.h"

static int lock_parent(struct dentry *dentry,
		       struct dentry **lower_dentry,
		       struct inode **lower_dir)
{
	struct dentry *lower_dir_dentry;

	lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
	*lower_dir = d_inode(lower_dir_dentry);
	*lower_dentry = ecryptfs_dentry_to_lower(dentry);

	inode_lock_nested(*lower_dir, I_MUTEX_PARENT);
	return (*lower_dentry)->d_parent == lower_dir_dentry ? 0 : -EINVAL;
}

static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
{
	return ecryptfs_inode_to_lower(inode) == lower_inode;
}

static int ecryptfs_inode_set(struct inode *inode, void *opaque)
{
	struct inode *lower_inode = opaque;

	ecryptfs_set_inode_lower(inode, lower_inode);
	fsstack_copy_attr_all(inode, lower_inode);
	/* i_size will be overwritten for encrypted regular files */
	fsstack_copy_inode_size(inode, lower_inode);
	inode->i_ino = lower_inode->i_ino;
	inode->i_mapping->a_ops = &ecryptfs_aops;

	if (S_ISLNK(inode->i_mode))
		inode->i_op = &ecryptfs_symlink_iops;
	else if (S_ISDIR(inode->i_mode))
		inode->i_op = &ecryptfs_dir_iops;
	else
		inode->i_op = &ecryptfs_main_iops;

	if (S_ISDIR(inode->i_mode))
		inode->i_fop = &ecryptfs_dir_fops;
	else if (special_file(inode->i_mode))
		init_special_inode(inode, inode->i_mode, inode->i_rdev);
	else
		inode->i_fop = &ecryptfs_main_fops;

	return 0;
}

static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
					  struct super_block *sb)
{
	struct inode *inode;

	if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
		return ERR_PTR(-EXDEV);

	/* Reject dealing with casefold directories. */
	if (IS_CASEFOLDED(lower_inode)) {
		pr_err_ratelimited("%s: Can't handle casefolded directory.\n",
				   __func__);
		return ERR_PTR(-EREMOTE);
	}

	if (!igrab(lower_inode))
		return ERR_PTR(-ESTALE);
	inode = iget5_locked(sb, (unsigned long)lower_inode,
			     ecryptfs_inode_test, ecryptfs_inode_set,
			     lower_inode);
	if (!inode) {
		iput(lower_inode);
		return ERR_PTR(-EACCES);
	}
	if (!(inode->i_state & I_NEW))
		iput(lower_inode);

	return inode;
}

struct inode *ecryptfs_get_inode(struct inode *lower_inode,
				 struct super_block *sb)
{
	struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);

	if (!IS_ERR(inode) && (inode->i_state & I_NEW))
		unlock_new_inode(inode);

	return inode;
}

/**
 * ecryptfs_interpose
 * @lower_dentry: Existing dentry in the lower filesystem
 * @dentry: ecryptfs' dentry
 * @sb: ecryptfs's super_block
 *
 * Interposes upper and lower dentries.
 *
 * Returns zero