LXR linux/fs/ecryptfs/super.c

   1/**
   2 * eCryptfs: Linux filesystem encryption layer
   3 *
   4 * Copyright (C) 1997-2003 Erez Zadok
   5 * Copyright (C) 2001-2003 Stony Brook University
   6 * Copyright (C) 2004-2006 International Business Machines Corp.
   7 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
   8 *              Michael C. Thompson <mcthomps@us.ibm.com>
   9 *
  10 * This program is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU General Public License as
  12 * published by the Free Software Foundation; either version 2 of the
  13 * License, or (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful, but
  16 * WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 * General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU General Public License
  21 * along with this program; if not, write to the Free Software
  22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  23 * 02111-1307, USA.
  24 */
  25
  26#include <linux/fs.h>
  27#include <linux/mount.h>
  28#include <linux/key.h>
  29#include <linux/slab.h>
  30#include <linux/seq_file.h>
  31#include <linux/file.h>
  32#include <linux/crypto.h>
  33#include "ecryptfs_kernel.h"
  34
  35struct kmem_cache *ecryptfs_inode_info_cache;
  36
  37/**
  38 * ecryptfs_alloc_inode - allocate an ecryptfs inode
  39 * @sb: Pointer to the ecryptfs super block
  40 *
  41 * Called to bring an inode into existence.
  42 *
  43 * Only handle allocation, setting up structures should be done in
  44 * ecryptfs_read_inode. This is because the kernel, between now and
  45 * then, will 0 out the private data pointer.
  46 *
  47 * Returns a pointer to a newly allocated inode, NULL otherwise
  48 */
  49static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
  50{
  51        struct ecryptfs_inode_info *inode_info;
  52        struct inode *inode = NULL;
  53
  54        inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  55        if (unlikely(!inode_info))
  56                goto out;
  57        ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
  58        mutex_init(&inode_info->lower_file_mutex);
  59        atomic_set(&inode_info->lower_file_count, 0);
  60        inode_info->lower_file = NULL;
  61        inode = &inode_info->vfs_inode;
  62out:
  63        return inode;
  64}
  65
  66static void ecryptfs_i_callback(struct rcu_head *head)
  67{
  68        struct inode *inode = container_of(head, struct inode, i_rcu);
  69        struct ecryptfs_inode_info *inode_info;
  70        inode_info = ecryptfs_inode_to_private(inode);
  71
  72        INIT_LIST_HEAD(&inode->i_dentry);
  73        kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  74}
  75
  76/**
  77 * ecryptfs_destroy_inode
  78 * @inode: The ecryptfs inode
  79 *
  80 * This is used during the final destruction of the inode.  All
  81 * allocation of memory related to the inode, including allocated
  82 * memory in the crypt_stat struct, will be released here.
  83 * There should be no chance that this deallocation will be missed.
  84 */
  85static void ecryptfs_destroy_inode(struct inode *inode)
  86{
  87        struct ecryptfs_inode_info *inode_info;
  88
  89        inode_info = ecryptfs_inode_to_private(inode);
  90        BUG_ON(inode_info->lower_file);
  91        ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  92        call_rcu(&inode->i_rcu, ecryptfs_i_callback);
  93}
  94
  95/**
  96 * ecryptfs_statfs
  97 * @sb: The ecryptfs super block
  98 * @buf: The struct kstatfs to fill in with stats
  99 *
 100 * Get the filesystem statistics. Currently, we let this pass right through
 101 * to the lower filesystem and take no action ourselves.
 102 */
 103static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 104{
 105        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 106
 107        if (!lower_dentry->d_sb->s_op->statfs)
 108                return -ENOSYS;
 109        return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 110}
 111
 112/**
 113 * ecryptfs_evict_inode
 114 * @inode - The ecryptfs inode
 115 *
 116 * Called by iput() when the inode reference count reached zero
 117 * and the inode is not hashed anywhere.  Used to clear anything
 118 * that needs to be, before the inode is completely destroyed and put
 119 * on the inode free list. We use this to drop out reference to the
 120 * lower inode.
 121 */
 122static void ecryptfs_evict_inode(struct inode *inode)
 123{
 124        truncate_inode_pages(&inode->i_data, 0);
 125        end_writeback(inode);
 126        iput(ecryptfs_inode_to_lower(inode));
 127}
 128
 129/**
 130 * ecryptfs_show_options
 131 *
 132 * Prints the mount options for a given superblock.
 133 * Returns zero; does not fail.
 134 */
 135static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 136{
 137        struct super_block *sb = mnt->mnt_sb;
 138        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 139                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 140        struct ecryptfs_global_auth_tok *walker;
 141
 142        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 143        list_for_each_entry(walker,
 144                            &mount_crypt_stat->global_auth_tok_list,
 145                            mount_crypt_stat_list) {
 146                if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 147                        seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 148                else
 149                        seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 150        }
 151        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 152
 153        seq_printf(m, ",ecryptfs_cipher=%s",
 154                mount_crypt_stat->global_default_cipher_name);
 155
 156        if (mount_crypt_stat->global_default_cipher_key_size)
 157                seq_printf(m, ",ecryptfs_key_bytes=%zd",
 158                           mount_crypt_stat->global_default_cipher_key_size);
 159        if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 160                seq_printf(m, ",ecryptfs_passthrough");
 161        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 162                seq_printf(m, ",ecryptfs_xattr_metadata");
 163        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 164                seq_printf(m, ",ecryptfs_encrypted_view");
 165        if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 166                seq_printf(m, ",ecryptfs_unlink_sigs");
 167        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 168                seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 169
 170        return 0;
 171}
 172
 173const struct super_operations ecryptfs_sops = {
 174        .alloc_inode = ecryptfs_alloc_inode,
 175        .destroy_inode = ecryptfs_destroy_inode,
 176        .drop_inode = generic_drop_inode,
 177        .statfs = ecryptfs_statfs,
 178        .remount_fs = NULL,
 179        .evict_inode = ecryptfs_evict_inode,
 180        .show_options = ecryptfs_show_options
 181};
 182