/**
   * eCryptfs: Linux filesystem encryption layer
   *
   * Copyright (C) 1997-2003 Erez Zadok
   * Copyright (C) 2001-2003 Stony Brook University
   * Copyright (C) 2004-2006 International Business Machines Corp.
   *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   *              Michael C. Thompson <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/fs.h>
  #include <linux/mount.h>
  #include <linux/key.h>
  #include <linux/slab.h>
  #include <linux/seq_file.h>
  #include <linux/file.h>
  #include <linux/crypto.h>
  #include <linux/statfs.h>
  #include <linux/magic.h>
  #include "ecryptfs_kernel.h"
  
  struct kmem_cache *ecryptfs_inode_info_cache;
  
  /**
   * ecryptfs_alloc_inode - allocate an ecryptfs inode
   * @sb: Pointer to the ecryptfs super block
   *
   * Called to bring an inode into existence.
   *
   * Only handle allocation, setting up structures should be done in
   * ecryptfs_read_inode. This is because the kernel, between now and
   * then, will 0 out the private data pointer.
   *
   * Returns a pointer to a newly allocated inode, NULL otherwise
   */
  static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
  {
  	struct ecryptfs_inode_info *inode_info;
  	struct inode *inode = NULL;
  
  	inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  	if (unlikely(!inode_info))
  		goto out;
  	ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
  	mutex_init(&inode_info->lower_file_mutex);
  	atomic_set(&inode_info->lower_file_count, 0);
  	inode_info->lower_file = NULL;
  	inode = &inode_info->vfs_inode;
  out:
  	return inode;
  }
  
  static void ecryptfs_i_callback(struct rcu_head *head)
  {
  	struct inode *inode = container_of(head, struct inode, i_rcu);
  	struct ecryptfs_inode_info *inode_info;
  	inode_info = ecryptfs_inode_to_private(inode);
  
  	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  }
  
  /**
   * ecryptfs_destroy_inode
   * @inode: The ecryptfs inode
   *
   * This is used during the final destruction of the inode.  All
   * allocation of memory related to the inode, including allocated
   * memory in the crypt_stat struct, will be released here.
   * There should be no chance that this deallocation will be missed.
   */
  static void ecryptfs_destroy_inode(struct inode *inode)
  {
  	struct ecryptfs_inode_info *inode_info;
  
  	inode_info = ecryptfs_inode_to_private(inode);
  	BUG_ON(inode_info->lower_file);
  	ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  	call_rcu(&inode->i_rcu, ecryptfs_i_callback);
  }
  
  /**
   * ecryptfs_statfs
   * @sb: The ecryptfs super block
   * @buf: The struct kstatfs to fill in with stats
   *
   * Get the filesystem statistics. Currently, we let this pass right through
   * to the lower filesystem and take no action ourselves.
   */
  static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  {
  	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  	int rc;
  
  	if (!lower_dentry->d_sb->s_op->statfs)
  		return -ENOSYS;
  
  	rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
  	if (rc)
  		return rc;
  
  	buf->f_type = ECRYPTFS_SUPER_MAGIC;
  	rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
  	       &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
  
  	return rc;
  }
  
  /**
   * ecryptfs_evict_inode
   * @inode - The ecryptfs inode
   *
   * Called by iput() when the inode reference count reached zero
   * and the inode is not hashed anywhere.  Used to clear anything
   * that needs to be, before the inode is completely destroyed and put
   * on the inode free list. We use this to drop out reference to the
   * lower inode.
   */
  static void ecryptfs_evict_inode(struct inode *inode)
  {
  	truncate_inode_pages(&inode->i_data, 0);
  	clear_inode(inode);
  	iput(ecryptfs_inode_to_lower(inode));
  }
  
  /**
   * ecryptfs_show_options
   *
   * Prints the mount options for a given superblock.
   * Returns zero; does not fail.
   */
  static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
  {
  	struct super_block *sb = root->d_sb;
  	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
  		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
  	struct ecryptfs_global_auth_tok *walker;
  
  	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
  	list_for_each_entry(walker,
  			    &mount_crypt_stat->global_auth_tok_list,
  			    mount_crypt_stat_list) {
  		if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
  			seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
  		else
  			seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
  	}
  	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
  
  	seq_printf(m, ",ecryptfs_cipher=%s",
  		mount_crypt_stat->global_default_cipher_name);
  
  	if (mount_crypt_stat->global_default_cipher_key_size)
  		seq_printf(m, ",ecryptfs_key_bytes=%zd",
  			   mount_crypt_stat->global_default_cipher_key_size);
  	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
  		seq_printf(m, ",ecryptfs_passthrough");
  	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
  		seq_printf(m, ",ecryptfs_xattr_metadata");
  	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
  		seq_printf(m, ",ecryptfs_encrypted_view");
  	if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
  		seq_printf(m, ",ecryptfs_unlink_sigs");
  	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
  		seq_printf(m, ",ecryptfs_mount_auth_tok_only");
  
  	return 0;
  }
  
  const struct super_operations ecryptfs_sops = {
  	.alloc_inode = ecryptfs_alloc_inode,
  	.destroy_inode = ecryptfs_destroy_inode,
  	.statfs = ecryptfs_statfs,
  	.remount_fs = NULL,
  	.evict_inode = ecryptfs_evict_inode,
  	.show_options = ecryptfs_show_options
  };