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        inode_info->lower_file = NULL;
  60        inode = &inode_info->vfs_inode;
  61out:
  62        return inode;
  63}
  64
  65static void ecryptfs_i_callback(struct rcu_head *head)
  66{
  67        struct inode *inode = container_of(head, struct inode, i_rcu);
  68        struct ecryptfs_inode_info *inode_info;
  69        inode_info = ecryptfs_inode_to_private(inode);
  70
  71        INIT_LIST_HEAD(&inode->i_dentry);
  72        kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  73}
  74
  75/**
  76 * ecryptfs_destroy_inode
  77 * @inode: The ecryptfs inode
  78 *
  79 * This is used during the final destruction of the inode.  All
  80 * allocation of memory related to the inode, including allocated
  81 * memory in the crypt_stat struct, will be released here. This
  82 * function also fput()'s the persistent file for the lower inode.
  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        if (inode_info->lower_file) {
  91                struct dentry *lower_dentry =
  92                        inode_info->lower_file->f_dentry;
  93
  94                BUG_ON(!lower_dentry);
  95                if (lower_dentry->d_inode) {
  96                        fput(inode_info->lower_file);
  97                        inode_info->lower_file = NULL;
  98                }
  99        }
 100        ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
 101        call_rcu(&inode->i_rcu, ecryptfs_i_callback);
 102}
 103
 104/**
 105 * ecryptfs_init_inode
 106 * @inode: The ecryptfs inode
 107 *
 108 * Set up the ecryptfs inode.
 109 */
 110void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
 111{
 112        ecryptfs_set_inode_lower(inode, lower_inode);
 113        inode->i_ino = lower_inode->i_ino;
 114        inode->i_version++;
 115        inode->i_op = &ecryptfs_main_iops;
 116        inode->i_fop = &ecryptfs_main_fops;
 117        inode->i_mapping->a_ops = &ecryptfs_aops;
 118}
 119
 120/**
 121 * ecryptfs_statfs
 122 * @sb: The ecryptfs super block
 123 * @buf: The struct kstatfs to fill in with stats
 124 *
 125 * Get the filesystem statistics. Currently, we let this pass right through
 126 * to the lower filesystem and take no action ourselves.
 127 */
 128static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 129{
 130        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 131
 132        if (!lower_dentry->d_sb->s_op->statfs)
 133                return -ENOSYS;
 134        return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 135}
 136
 137/**
 138 * ecryptfs_evict_inode
 139 * @inode - The ecryptfs inode
 140 *
 141 * Called by iput() when the inode reference count reached zero
 142 * and the inode is not hashed anywhere.  Used to clear anything
 143 * that needs to be, before the inode is completely destroyed and put
 144 * on the inode free list. We use this to drop out reference to the
 145 * lower inode.
 146 */
 147static void ecryptfs_evict_inode(struct inode *inode)
 148{
 149        truncate_inode_pages(&inode->i_data, 0);
 150        end_writeback(inode);
 151        iput(ecryptfs_inode_to_lower(inode));
 152}
 153
 154/**
 155 * ecryptfs_show_options
 156 *
 157 * Prints the mount options for a given superblock.
 158 * Returns zero; does not fail.
 159 */
 160static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 161{
 162        struct super_block *sb = mnt->mnt_sb;
 163        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 164                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 165        struct ecryptfs_global_auth_tok *walker;
 166
 167        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 168        list_for_each_entry(walker,
 169                            &mount_crypt_stat->global_auth_tok_list,
 170                            mount_crypt_stat_list) {
 171                if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 172                        seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 173                else
 174                        seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 175        }
 176        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 177
 178        seq_printf(m, ",ecryptfs_cipher=%s",
 179                mount_crypt_stat->global_default_cipher_name);
 180
 181        if (mount_crypt_stat->global_default_cipher_key_size)
 182                seq_printf(m, ",ecryptfs_key_bytes=%zd",
 183                           mount_crypt_stat->global_default_cipher_key_size);
 184        if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 185                seq_printf(m, ",ecryptfs_passthrough");
 186        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 187                seq_printf(m, ",ecryptfs_xattr_metadata");
 188        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 189                seq_printf(m, ",ecryptfs_encrypted_view");
 190        if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 191                seq_printf(m, ",ecryptfs_unlink_sigs");
 192        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 193                seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 194
 195        return 0;
 196}
 197
 198const struct super_operations ecryptfs_sops = {
 199        .alloc_inode = ecryptfs_alloc_inode,
 200        .destroy_inode = ecryptfs_destroy_inode,
 201        .drop_inode = generic_delete_inode,
 202        .statfs = ecryptfs_statfs,
 203        .remount_fs = NULL,
 204        .evict_inode = ecryptfs_evict_inode,
 205        .show_options = ecryptfs_show_options
 206};
 207