/**
   * eCryptfs: Linux filesystem encryption layer
   *
   * Copyright (C) 1997-2003 Erez Zadok
   * Copyright (C) 2001-2003 Stony Brook University

   * Copyright (C) 2004-2007 International Business Machines Corp.

   *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   *              Michael C. Thompson <mcthomps@us.ibm.com>

   *              Tyler Hicks <tyhicks@ou.edu>

   *
   * 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/dcache.h>
  #include <linux/file.h>
  #include <linux/module.h>
  #include <linux/namei.h>
  #include <linux/skbuff.h>
  #include <linux/crypto.h>

  #include <linux/mount.h>

  #include <linux/pagemap.h>
  #include <linux/key.h>
  #include <linux/parser.h>

  #include <linux/fs_stack.h>

  #include <linux/slab.h>

  #include <linux/magic.h>

  #include "ecryptfs_kernel.h"
  
  /**
   * Module parameter that defines the ecryptfs_verbosity level.
   */
  int ecryptfs_verbosity = 0;
  
  module_param(ecryptfs_verbosity, int, 0);
  MODULE_PARM_DESC(ecryptfs_verbosity,
  		 "Initial verbosity level (0 or 1; defaults to "
  		 "0, which is Quiet)");

  /**

   * Module parameter that defines the number of message buffer elements

   */
  unsigned int ecryptfs_message_buf_len = ECRYPTFS_DEFAULT_MSG_CTX_ELEMS;
  
  module_param(ecryptfs_message_buf_len, uint, 0);
  MODULE_PARM_DESC(ecryptfs_message_buf_len,
  		 "Number of message buffer elements");
  
  /**
   * Module parameter that defines the maximum guaranteed amount of time to wait

   * for a response from ecryptfsd.  The actual sleep time will be, more than

   * likely, a small amount greater than this specified value, but only less if

   * the message successfully arrives.

   */
  signed long ecryptfs_message_wait_timeout = ECRYPTFS_MAX_MSG_CTX_TTL / HZ;
  
  module_param(ecryptfs_message_wait_timeout, long, 0);
  MODULE_PARM_DESC(ecryptfs_message_wait_timeout,
  		 "Maximum number of seconds that an operation will "
  		 "sleep while waiting for a message response from "
  		 "userspace");
  
  /**
   * Module parameter that is an estimate of the maximum number of users
   * that will be concurrently using eCryptfs. Set this to the right
   * value to balance performance and memory use.
   */
  unsigned int ecryptfs_number_of_users = ECRYPTFS_DEFAULT_NUM_USERS;
  
  module_param(ecryptfs_number_of_users, uint, 0);
  MODULE_PARM_DESC(ecryptfs_number_of_users, "An estimate of the number of "
  		 "concurrent users of eCryptfs");

  void __ecryptfs_printk(const char *fmt, ...)
  {
  	va_list args;
  	va_start(args, fmt);
  	if (fmt[1] == '7') { /* KERN_DEBUG */
  		if (ecryptfs_verbosity >= 1)
  			vprintk(fmt, args);
  	} else
  		vprintk(fmt, args);
  	va_end(args);
  }
  
  /**

   * ecryptfs_init_lower_file

   * @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
   *                   the lower dentry and the lower mount set
   *
   * eCryptfs only ever keeps a single open file for every lower
   * inode. All I/O operations to the lower inode occur through that
   * file. When the first eCryptfs dentry that interposes with the first
   * lower dentry for that inode is created, this function creates the

   * lower file struct and associates it with the eCryptfs
   * inode. When all eCryptfs files associated with the inode are released, the
   * file is closed.

   *

   * The lower file will be opened with read/write permissions, if

   * possible. Otherwise, it is opened read-only.
   *

   * This function does nothing if a lower file is already

   * associated with the eCryptfs inode.
   *
   * Returns zero on success; non-zero otherwise
   */

  static int ecryptfs_init_lower_file(struct dentry *dentry,
  				    struct file **lower_file)

  {

  	const struct cred *cred = current_cred();

  	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
  	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
  	int rc;
  
  	rc = ecryptfs_privileged_open(lower_file, lower_dentry, lower_mnt,
  				      cred);
  	if (rc) {
  		printk(KERN_ERR "Error opening lower file "
  		       "for lower_dentry [0x%p] and lower_mnt [0x%p]; "
  		       "rc = [%d]
  ", lower_dentry, lower_mnt, rc);
  		(*lower_file) = NULL;
  	}
  	return rc;
  }

  int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)

  {

  	struct ecryptfs_inode_info *inode_info;

  	int count, rc = 0;

  	inode_info = ecryptfs_inode_to_private(inode);

  	mutex_lock(&inode_info->lower_file_mutex);
  	count = atomic_inc_return(&inode_info->lower_file_count);
  	if (WARN_ON_ONCE(count < 1))
  		rc = -EINVAL;
  	else if (count == 1) {
  		rc = ecryptfs_init_lower_file(dentry,
  					      &inode_info->lower_file);
  		if (rc)
  			atomic_set(&inode_info->lower_file_count, 0);

  	}

  	mutex_unlock(&inode_info->lower_file_mutex);

  	return rc;
  }

  void ecryptfs_put_lower_file(struct inode *inode)
  {
  	struct ecryptfs_inode_info *inode_info;
  
  	inode_info = ecryptfs_inode_to_private(inode);
  	if (atomic_dec_and_mutex_lock(&inode_info->lower_file_count,
  				      &inode_info->lower_file_mutex)) {
  		fput(inode_info->lower_file);
  		inode_info->lower_file = NULL;
  		mutex_unlock(&inode_info->lower_file_mutex);
  	}
  }

  enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig,
         ecryptfs_opt_cipher, ecryptfs_opt_ecryptfs_cipher,
         ecryptfs_opt_ecryptfs_key_bytes,

         ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,

         ecryptfs_opt_encrypted_view, ecryptfs_opt_fnek_sig,
         ecryptfs_opt_fn_cipher, ecryptfs_opt_fn_cipher_key_bytes,

         ecryptfs_opt_unlink_sigs, ecryptfs_opt_mount_auth_tok_only,

         ecryptfs_opt_check_dev_ruid,

         ecryptfs_opt_err };

  static const match_table_t tokens = {

  	{ecryptfs_opt_sig, "sig=%s"},
  	{ecryptfs_opt_ecryptfs_sig, "ecryptfs_sig=%s"},

  	{ecryptfs_opt_cipher, "cipher=%s"},
  	{ecryptfs_opt_ecryptfs_cipher, "ecryptfs_cipher=%s"},
  	{ecryptfs_opt_ecryptfs_key_bytes, "ecryptfs_key_bytes=%u"},
  	{ecryptfs_opt_passthrough, "ecryptfs_passthrough"},

  	{ecryptfs_opt_xattr_metadata, "ecryptfs_xattr_metadata"},
  	{ecryptfs_opt_encrypted_view, "ecryptfs_encrypted_view"},

  	{ecryptfs_opt_fnek_sig, "ecryptfs_fnek_sig=%s"},
  	{ecryptfs_opt_fn_cipher, "ecryptfs_fn_cipher=%s"},
  	{ecryptfs_opt_fn_cipher_key_bytes, "ecryptfs_fn_key_bytes=%u"},

  	{ecryptfs_opt_unlink_sigs, "ecryptfs_unlink_sigs"},

  	{ecryptfs_opt_mount_auth_tok_only, "ecryptfs_mount_auth_tok_only"},

  	{ecryptfs_opt_check_dev_ruid, "ecryptfs_check_dev_ruid"},

  	{ecryptfs_opt_err, NULL}
  };

  static int ecryptfs_init_global_auth_toks(
  	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)

  {

  	struct ecryptfs_global_auth_tok *global_auth_tok;

  	struct ecryptfs_auth_tok *auth_tok;

  	int rc = 0;

  	list_for_each_entry(global_auth_tok,
  			    &mount_crypt_stat->global_auth_tok_list,
  			    mount_crypt_stat_list) {

  		rc = ecryptfs_keyring_auth_tok_for_sig(

  			&global_auth_tok->global_auth_tok_key, &auth_tok,

  			global_auth_tok->sig);
  		if (rc) {

  			printk(KERN_ERR "Could not find valid key in user "
  			       "session keyring for sig specified in mount "
  			       "option: [%s]
  ", global_auth_tok->sig);
  			global_auth_tok->flags |= ECRYPTFS_AUTH_TOK_INVALID;

  			goto out;

  		} else {

  			global_auth_tok->flags &= ~ECRYPTFS_AUTH_TOK_INVALID;

  			up_write(&(global_auth_tok->global_auth_tok_key)->sem);
  		}

  	}

  out:

  	return rc;
  }

  static void ecryptfs_init_mount_crypt_stat(
  	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
  {
  	memset((void *)mount_crypt_stat, 0,
  	       sizeof(struct ecryptfs_mount_crypt_stat));
  	INIT_LIST_HEAD(&mount_crypt_stat->global_auth_tok_list);
  	mutex_init(&mount_crypt_stat->global_auth_tok_list_mutex);
  	mount_crypt_stat->flags |= ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED;
  }

  /**
   * ecryptfs_parse_options
   * @sb: The ecryptfs super block

   * @options: The options passed to the kernel

   * @check_ruid: set to 1 if device uid should be checked against the ruid

   *
   * Parse mount options:
   * debug=N 	   - ecryptfs_verbosity level for debug output
   * sig=XXX	   - description(signature) of the key to use
   *
   * Returns the dentry object of the lower-level (lower/interposed)
   * directory; We want to mount our stackable file system on top of
   * that lower directory.
   *
   * The signature of the key to use must be the description of a key
   * already in the keyring. Mounting will fail if the key can not be
   * found.
   *
   * Returns zero on success; non-zero on error
   */

  static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
  				  uid_t *check_ruid)

  {
  	char *p;
  	int rc = 0;
  	int sig_set = 0;
  	int cipher_name_set = 0;

  	int fn_cipher_name_set = 0;

  	int cipher_key_bytes;
  	int cipher_key_bytes_set = 0;

  	int fn_cipher_key_bytes;
  	int fn_cipher_key_bytes_set = 0;

  	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =

  		&sbi->mount_crypt_stat;

  	substring_t args[MAX_OPT_ARGS];
  	int token;
  	char *sig_src;

  	char *cipher_name_dst;
  	char *cipher_name_src;

  	char *fn_cipher_name_dst;
  	char *fn_cipher_name_src;
  	char *fnek_dst;
  	char *fnek_src;

  	char *cipher_key_bytes_src;

  	char *fn_cipher_key_bytes_src;

  	*check_ruid = 0;

  	if (!options) {
  		rc = -EINVAL;
  		goto out;
  	}

  	ecryptfs_init_mount_crypt_stat(mount_crypt_stat);

  	while ((p = strsep(&options, ",")) != NULL) {
  		if (!*p)
  			continue;
  		token = match_token(p, tokens, args);
  		switch (token) {
  		case ecryptfs_opt_sig:
  		case ecryptfs_opt_ecryptfs_sig:
  			sig_src = args[0].from;

  			rc = ecryptfs_add_global_auth_tok(mount_crypt_stat,

  							  sig_src, 0);

  			if (rc) {
  				printk(KERN_ERR "Error attempting to register "
  				       "global sig; rc = [%d]
  ", rc);
  				goto out;
  			}

  			sig_set = 1;
  			break;

  		case ecryptfs_opt_cipher:
  		case ecryptfs_opt_ecryptfs_cipher:
  			cipher_name_src = args[0].from;
  			cipher_name_dst =
  				mount_crypt_stat->
  				global_default_cipher_name;
  			strncpy(cipher_name_dst, cipher_name_src,
  				ECRYPTFS_MAX_CIPHER_NAME_SIZE);

  			cipher_name_dst[ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';

  			cipher_name_set = 1;
  			break;
  		case ecryptfs_opt_ecryptfs_key_bytes:
  			cipher_key_bytes_src = args[0].from;
  			cipher_key_bytes =
  				(int)simple_strtol(cipher_key_bytes_src,
  						   &cipher_key_bytes_src, 0);
  			mount_crypt_stat->global_default_cipher_key_size =
  				cipher_key_bytes;

  			cipher_key_bytes_set = 1;
  			break;
  		case ecryptfs_opt_passthrough:
  			mount_crypt_stat->flags |=
  				ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED;
  			break;

  		case ecryptfs_opt_xattr_metadata:
  			mount_crypt_stat->flags |=
  				ECRYPTFS_XATTR_METADATA_ENABLED;
  			break;
  		case ecryptfs_opt_encrypted_view:
  			mount_crypt_stat->flags |=
  				ECRYPTFS_XATTR_METADATA_ENABLED;
  			mount_crypt_stat->flags |=
  				ECRYPTFS_ENCRYPTED_VIEW_ENABLED;
  			break;

  		case ecryptfs_opt_fnek_sig:
  			fnek_src = args[0].from;
  			fnek_dst =
  				mount_crypt_stat->global_default_fnek_sig;
  			strncpy(fnek_dst, fnek_src, ECRYPTFS_SIG_SIZE_HEX);
  			mount_crypt_stat->global_default_fnek_sig[
  				ECRYPTFS_SIG_SIZE_HEX] = '\0';
  			rc = ecryptfs_add_global_auth_tok(
  				mount_crypt_stat,

  				mount_crypt_stat->global_default_fnek_sig,
  				ECRYPTFS_AUTH_TOK_FNEK);

  			if (rc) {
  				printk(KERN_ERR "Error attempting to register "
  				       "global fnek sig [%s]; rc = [%d]
  ",
  				       mount_crypt_stat->global_default_fnek_sig,
  				       rc);
  				goto out;
  			}
  			mount_crypt_stat->flags |=
  				(ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES
  				 | ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK);
  			break;
  		case ecryptfs_opt_fn_cipher:
  			fn_cipher_name_src = args[0].from;
  			fn_cipher_name_dst =
  				mount_crypt_stat->global_default_fn_cipher_name;
  			strncpy(fn_cipher_name_dst, fn_cipher_name_src,
  				ECRYPTFS_MAX_CIPHER_NAME_SIZE);
  			mount_crypt_stat->global_default_fn_cipher_name[
  				ECRYPTFS_MAX_CIPHER_NAME_SIZE] = '\0';
  			fn_cipher_name_set = 1;
  			break;
  		case ecryptfs_opt_fn_cipher_key_bytes:
  			fn_cipher_key_bytes_src = args[0].from;
  			fn_cipher_key_bytes =
  				(int)simple_strtol(fn_cipher_key_bytes_src,
  						   &fn_cipher_key_bytes_src, 0);
  			mount_crypt_stat->global_default_fn_cipher_key_bytes =
  				fn_cipher_key_bytes;
  			fn_cipher_key_bytes_set = 1;
  			break;

  		case ecryptfs_opt_unlink_sigs:
  			mount_crypt_stat->flags |= ECRYPTFS_UNLINK_SIGS;
  			break;

  		case ecryptfs_opt_mount_auth_tok_only:
  			mount_crypt_stat->flags |=
  				ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY;
  			break;

  		case ecryptfs_opt_check_dev_ruid:
  			*check_ruid = 1;
  			break;

  		case ecryptfs_opt_err:
  		default:

  			printk(KERN_WARNING
  			       "%s: eCryptfs: unrecognized option [%s]
  ",
  			       __func__, p);

  		}
  	}

  	if (!sig_set) {
  		rc = -EINVAL;

  		ecryptfs_printk(KERN_ERR, "You must supply at least one valid "
  				"auth tok signature as a mount "

  				"parameter; see the eCryptfs README
  ");
  		goto out;
  	}
  	if (!cipher_name_set) {

  		int cipher_name_len = strlen(ECRYPTFS_DEFAULT_CIPHER);
  
  		BUG_ON(cipher_name_len >= ECRYPTFS_MAX_CIPHER_NAME_SIZE);

  		strcpy(mount_crypt_stat->global_default_cipher_name,
  		       ECRYPTFS_DEFAULT_CIPHER);

  	}

  	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
  	    && !fn_cipher_name_set)
  		strcpy(mount_crypt_stat->global_default_fn_cipher_name,
  		       mount_crypt_stat->global_default_cipher_name);
  	if (!cipher_key_bytes_set)

  		mount_crypt_stat->global_default_cipher_key_size = 0;

  	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
  	    && !fn_cipher_key_bytes_set)
  		mount_crypt_stat->global_default_fn_cipher_key_bytes =
  			mount_crypt_stat->global_default_cipher_key_size;

  	mutex_lock(&key_tfm_list_mutex);
  	if (!ecryptfs_tfm_exists(mount_crypt_stat->global_default_cipher_name,

  				 NULL)) {

  		rc = ecryptfs_add_new_key_tfm(
  			NULL, mount_crypt_stat->global_default_cipher_name,
  			mount_crypt_stat->global_default_cipher_key_size);

  		if (rc) {
  			printk(KERN_ERR "Error attempting to initialize "
  			       "cipher with name = [%s] and key size = [%td]; "
  			       "rc = [%d]
  ",
  			       mount_crypt_stat->global_default_cipher_name,
  			       mount_crypt_stat->global_default_cipher_key_size,
  			       rc);
  			rc = -EINVAL;
  			mutex_unlock(&key_tfm_list_mutex);
  			goto out;
  		}
  	}
  	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
  	    && !ecryptfs_tfm_exists(
  		    mount_crypt_stat->global_default_fn_cipher_name, NULL)) {
  		rc = ecryptfs_add_new_key_tfm(
  			NULL, mount_crypt_stat->global_default_fn_cipher_name,
  			mount_crypt_stat->global_default_fn_cipher_key_bytes);
  		if (rc) {
  			printk(KERN_ERR "Error attempting to initialize "
  			       "cipher with name = [%s] and key size = [%td]; "
  			       "rc = [%d]
  ",
  			       mount_crypt_stat->global_default_fn_cipher_name,
  			       mount_crypt_stat->global_default_fn_cipher_key_bytes,
  			       rc);
  			rc = -EINVAL;
  			mutex_unlock(&key_tfm_list_mutex);
  			goto out;
  		}

  	}

  	mutex_unlock(&key_tfm_list_mutex);

  	rc = ecryptfs_init_global_auth_toks(mount_crypt_stat);

  	if (rc)

  		printk(KERN_WARNING "One or more global auth toks could not "
  		       "properly register; rc = [%d]
  ", rc);

  out:
  	return rc;
  }
  
  struct kmem_cache *ecryptfs_sb_info_cache;

  static struct file_system_type ecryptfs_fs_type;

  
  /**

   * ecryptfs_get_sb
   * @fs_type
   * @flags
   * @dev_name: The path to mount over
   * @raw_data: The options passed into the kernel

   */

  static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags,
  			const char *dev_name, void *raw_data)

  {

  	struct super_block *s;
  	struct ecryptfs_sb_info *sbi;
  	struct ecryptfs_dentry_info *root_info;
  	const char *err = "Getting sb failed";

  	struct inode *inode;
  	struct path path;

  	uid_t check_ruid;

  	int rc;

  	sbi = kmem_cache_zalloc(ecryptfs_sb_info_cache, GFP_KERNEL);
  	if (!sbi) {
  		rc = -ENOMEM;

  		goto out;
  	}

  	rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);

  	if (rc) {

  		err = "Error parsing options";
  		goto out;

  	}

  
  	s = sget(fs_type, NULL, set_anon_super, NULL);
  	if (IS_ERR(s)) {
  		rc = PTR_ERR(s);
  		goto out;
  	}
  
  	s->s_flags = flags;
  	rc = bdi_setup_and_register(&sbi->bdi, "ecryptfs", BDI_CAP_MAP_COPY);

  	if (rc)
  		goto out1;

  
  	ecryptfs_set_superblock_private(s, sbi);
  	s->s_bdi = &sbi->bdi;
  
  	/* ->kill_sb() will take care of sbi after that point */
  	sbi = NULL;
  	s->s_op = &ecryptfs_sops;

  	s->s_d_op = &ecryptfs_dops;

  	err = "Reading sb failed";
  	rc = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
  	if (rc) {
  		ecryptfs_printk(KERN_WARNING, "kern_path() failed
  ");
  		goto out1;
  	}
  	if (path.dentry->d_sb->s_type == &ecryptfs_fs_type) {
  		rc = -EINVAL;
  		printk(KERN_ERR "Mount on filesystem of type "
  			"eCryptfs explicitly disallowed due to "
  			"known incompatibilities
  ");
  		goto out_free;
  	}

  
  	if (check_ruid && path.dentry->d_inode->i_uid != current_uid()) {
  		rc = -EPERM;
  		printk(KERN_ERR "Mount of device (uid: %d) not owned by "
  		       "requested user (uid: %d)
  ",
  		       path.dentry->d_inode->i_uid, current_uid());
  		goto out_free;
  	}

  	ecryptfs_set_superblock_lower(s, path.dentry->d_sb);
  	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
  	s->s_blocksize = path.dentry->d_sb->s_blocksize;

  	s->s_magic = ECRYPTFS_SUPER_MAGIC;

  
  	inode = ecryptfs_get_inode(path.dentry->d_inode, s);
  	rc = PTR_ERR(inode);
  	if (IS_ERR(inode))
  		goto out_free;
  
  	s->s_root = d_alloc_root(inode);

  	if (!s->s_root) {

  		iput(inode);
  		rc = -ENOMEM;
  		goto out_free;

  	}

  	rc = -ENOMEM;

  	root_info = kmem_cache_zalloc(ecryptfs_dentry_info_cache, GFP_KERNEL);

  	if (!root_info)
  		goto out_free;

  	/* ->kill_sb() will take care of root_info */
  	ecryptfs_set_dentry_private(s->s_root, root_info);

  	ecryptfs_set_dentry_lower(s->s_root, path.dentry);
  	ecryptfs_set_dentry_lower_mnt(s->s_root, path.mnt);

  	s->s_flags |= MS_ACTIVE;

  	return dget(s->s_root);

  out_free:
  	path_put(&path);
  out1:
  	deactivate_locked_super(s);

  out:

  	if (sbi) {
  		ecryptfs_destroy_mount_crypt_stat(&sbi->mount_crypt_stat);
  		kmem_cache_free(ecryptfs_sb_info_cache, sbi);
  	}
  	printk(KERN_ERR "%s; rc = [%d]
  ", err, rc);

  	return ERR_PTR(rc);

  }
  
  /**
   * ecryptfs_kill_block_super
   * @sb: The ecryptfs super block
   *
   * Used to bring the superblock down and free the private data.

   */
  static void ecryptfs_kill_block_super(struct super_block *sb)
  {

  	struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
  	kill_anon_super(sb);
  	if (!sb_info)
  		return;
  	ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
  	bdi_destroy(&sb_info->bdi);
  	kmem_cache_free(ecryptfs_sb_info_cache, sb_info);

  }
  
  static struct file_system_type ecryptfs_fs_type = {
  	.owner = THIS_MODULE,
  	.name = "ecryptfs",

  	.mount = ecryptfs_mount,

  	.kill_sb = ecryptfs_kill_block_super,
  	.fs_flags = 0
  };
  
  /**
   * inode_info_init_once
   *
   * Initializes the ecryptfs_inode_info_cache when it is created
   */
  static void

  inode_info_init_once(void *vptr)

  {
  	struct ecryptfs_inode_info *ei = (struct ecryptfs_inode_info *)vptr;

  	inode_init_once(&ei->vfs_inode);

  }
  
  static struct ecryptfs_cache_info {

  	struct kmem_cache **cache;

  	const char *name;
  	size_t size;

  	void (*ctor)(void *obj);

  } ecryptfs_cache_infos[] = {
  	{
  		.cache = &ecryptfs_auth_tok_list_item_cache,
  		.name = "ecryptfs_auth_tok_list_item",
  		.size = sizeof(struct ecryptfs_auth_tok_list_item),
  	},
  	{
  		.cache = &ecryptfs_file_info_cache,
  		.name = "ecryptfs_file_cache",
  		.size = sizeof(struct ecryptfs_file_info),
  	},
  	{
  		.cache = &ecryptfs_dentry_info_cache,
  		.name = "ecryptfs_dentry_info_cache",
  		.size = sizeof(struct ecryptfs_dentry_info),
  	},
  	{
  		.cache = &ecryptfs_inode_info_cache,
  		.name = "ecryptfs_inode_cache",
  		.size = sizeof(struct ecryptfs_inode_info),
  		.ctor = inode_info_init_once,
  	},
  	{
  		.cache = &ecryptfs_sb_info_cache,
  		.name = "ecryptfs_sb_cache",
  		.size = sizeof(struct ecryptfs_sb_info),
  	},
  	{

  		.cache = &ecryptfs_header_cache,
  		.name = "ecryptfs_headers",

  		.size = PAGE_CACHE_SIZE,
  	},
  	{

  		.cache = &ecryptfs_xattr_cache,
  		.name = "ecryptfs_xattr_cache",
  		.size = PAGE_CACHE_SIZE,
  	},
  	{

  		.cache = &ecryptfs_key_record_cache,
  		.name = "ecryptfs_key_record_cache",
  		.size = sizeof(struct ecryptfs_key_record),
  	},

  	{
  		.cache = &ecryptfs_key_sig_cache,
  		.name = "ecryptfs_key_sig_cache",
  		.size = sizeof(struct ecryptfs_key_sig),
  	},
  	{
  		.cache = &ecryptfs_global_auth_tok_cache,
  		.name = "ecryptfs_global_auth_tok_cache",
  		.size = sizeof(struct ecryptfs_global_auth_tok),
  	},
  	{
  		.cache = &ecryptfs_key_tfm_cache,
  		.name = "ecryptfs_key_tfm_cache",
  		.size = sizeof(struct ecryptfs_key_tfm),
  	},

  	{
  		.cache = &ecryptfs_open_req_cache,
  		.name = "ecryptfs_open_req_cache",
  		.size = sizeof(struct ecryptfs_open_req),
  	},

  };
  
  static void ecryptfs_free_kmem_caches(void)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
  		struct ecryptfs_cache_info *info;
  
  		info = &ecryptfs_cache_infos[i];
  		if (*(info->cache))
  			kmem_cache_destroy(*(info->cache));
  	}
  }
  
  /**
   * ecryptfs_init_kmem_caches
   *
   * Returns zero on success; non-zero otherwise
   */
  static int ecryptfs_init_kmem_caches(void)
  {
  	int i;
  
  	for (i = 0; i < ARRAY_SIZE(ecryptfs_cache_infos); i++) {
  		struct ecryptfs_cache_info *info;
  
  		info = &ecryptfs_cache_infos[i];
  		*(info->cache) = kmem_cache_create(info->name, info->size,

  				0, SLAB_HWCACHE_ALIGN, info->ctor);

  		if (!*(info->cache)) {
  			ecryptfs_free_kmem_caches();
  			ecryptfs_printk(KERN_WARNING, "%s: "
  					"kmem_cache_create failed
  ",
  					info->name);
  			return -ENOMEM;
  		}
  	}
  	return 0;
  }

  static struct kobject *ecryptfs_kobj;

  static ssize_t version_show(struct kobject *kobj,
  			    struct kobj_attribute *attr, char *buff)

  {
  	return snprintf(buff, PAGE_SIZE, "%d
  ", ECRYPTFS_VERSIONING_MASK);
  }

  static struct kobj_attribute version_attr = __ATTR_RO(version);

  static struct attribute *attributes[] = {
  	&version_attr.attr,

  	NULL,
  };
  
  static struct attribute_group attr_group = {
  	.attrs = attributes,
  };

  
  static int do_sysfs_registration(void)
  {
  	int rc;

  	ecryptfs_kobj = kobject_create_and_add("ecryptfs", fs_kobj);
  	if (!ecryptfs_kobj) {

  		printk(KERN_ERR "Unable to create ecryptfs kset
  ");
  		rc = -ENOMEM;

  		goto out;
  	}

  	rc = sysfs_create_group(ecryptfs_kobj, &attr_group);

  	if (rc) {
  		printk(KERN_ERR

  		       "Unable to create ecryptfs version attributes
  ");

  		kobject_put(ecryptfs_kobj);

  	}
  out:
  	return rc;
  }

  static void do_sysfs_unregistration(void)
  {

  	sysfs_remove_group(ecryptfs_kobj, &attr_group);

  	kobject_put(ecryptfs_kobj);

  }

  static int __init ecryptfs_init(void)
  {
  	int rc;
  
  	if (ECRYPTFS_DEFAULT_EXTENT_SIZE > PAGE_CACHE_SIZE) {
  		rc = -EINVAL;
  		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
  				"larger than the host's page size, and so "
  				"eCryptfs cannot run on this system. The "

  				"default eCryptfs extent size is [%u] bytes; "
  				"the page size is [%lu] bytes.
  ",
  				ECRYPTFS_DEFAULT_EXTENT_SIZE,
  				(unsigned long)PAGE_CACHE_SIZE);

  		goto out;
  	}
  	rc = ecryptfs_init_kmem_caches();
  	if (rc) {
  		printk(KERN_ERR
  		       "Failed to allocate one or more kmem_cache objects
  ");
  		goto out;
  	}
  	rc = register_filesystem(&ecryptfs_fs_type);
  	if (rc) {
  		printk(KERN_ERR "Failed to register filesystem
  ");

  		goto out_free_kmem_caches;

  	}

  	rc = do_sysfs_registration();
  	if (rc) {
  		printk(KERN_ERR "sysfs registration failed
  ");

  		goto out_unregister_filesystem;

  	}

  	rc = ecryptfs_init_kthread();
  	if (rc) {
  		printk(KERN_ERR "%s: kthread initialization failed; "
  		       "rc = [%d]
  ", __func__, rc);
  		goto out_do_sysfs_unregistration;
  	}

  	rc = ecryptfs_init_messaging();

  	if (rc) {

  		printk(KERN_ERR "Failure occurred while attempting to "

  				"initialize the communications channel to "
  				"ecryptfsd
  ");

  		goto out_destroy_kthread;

  	}
  	rc = ecryptfs_init_crypto();
  	if (rc) {
  		printk(KERN_ERR "Failure whilst attempting to init crypto; "
  		       "rc = [%d]
  ", rc);

  		goto out_release_messaging;

  	}

  	if (ecryptfs_verbosity > 0)
  		printk(KERN_CRIT "eCryptfs verbosity set to %d. Secret values "
  			"will be written to the syslog!
  ", ecryptfs_verbosity);

  	goto out;
  out_release_messaging:

  	ecryptfs_release_messaging();

  out_destroy_kthread:
  	ecryptfs_destroy_kthread();

  out_do_sysfs_unregistration:
  	do_sysfs_unregistration();
  out_unregister_filesystem:
  	unregister_filesystem(&ecryptfs_fs_type);
  out_free_kmem_caches:
  	ecryptfs_free_kmem_caches();

  out:
  	return rc;
  }
  
  static void __exit ecryptfs_exit(void)
  {

  	int rc;
  
  	rc = ecryptfs_destroy_crypto();
  	if (rc)
  		printk(KERN_ERR "Failure whilst attempting to destroy crypto; "
  		       "rc = [%d]
  ", rc);

  	ecryptfs_release_messaging();

  	ecryptfs_destroy_kthread();

  	do_sysfs_unregistration();

  	unregister_filesystem(&ecryptfs_fs_type);
  	ecryptfs_free_kmem_caches();
  }
  
  MODULE_AUTHOR("Michael A. Halcrow <mhalcrow@us.ibm.com>");
  MODULE_DESCRIPTION("eCryptfs");
  
  MODULE_LICENSE("GPL");
  
  module_init(ecryptfs_init)
  module_exit(ecryptfs_exit)