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/statfs.h>
  33#include <linux/magic.h>
  34#include "ecryptfs_kernel.h"
  35
  36struct kmem_cache *ecryptfs_inode_info_cache;
  37
  38/**
  39 * ecryptfs_alloc_inode - allocate an ecryptfs inode
  40 * @sb: Pointer to the ecryptfs super block
  41 *
  42 * Called to bring an inode into existence.
  43 *
  44 * Only handle allocation, setting up structures should be done in
  45 * ecryptfs_read_inode. This is because the kernel, between now and
  46 * then, will 0 out the private data pointer.
  47 *
  48 * Returns a pointer to a newly allocated inode, NULL otherwise
  49 */
  50static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
  51{
  52        struct ecryptfs_inode_info *inode_info;
  53        struct inode *inode = NULL;
  54
  55        inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  56        if (unlikely(!inode_info))
  57                goto out;
  58        ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
  59        mutex_init(&inode_info->lower_file_mutex);
  60        atomic_set(&inode_info->lower_file_count, 0);
  61        inode_info->lower_file = NULL;
  62        inode = &inode_info->vfs_inode;
  63out:
  64        return inode;
  65}
  66
  67static void ecryptfs_i_callback(struct rcu_head *head)
  68{
  69        struct inode *inode = container_of(head, struct inode, i_rcu);
  70        struct ecryptfs_inode_info *inode_info;
  71        inode_info = ecryptfs_inode_to_private(inode);
  72
  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        int rc;
 107
 108        if (!lower_dentry->d_sb->s_op->statfs)
 109                return -ENOSYS;
 110
 111        rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 112        if (rc)
 113                return rc;
 114
 115        buf->f_type = ECRYPTFS_SUPER_MAGIC;
 116        rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
 117               &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
 118
 119        return rc;
 120}
 121
 122/**
 123 * ecryptfs_evict_inode
 124 * @inode - The ecryptfs inode
 125 *
 126 * Called by iput() when the inode reference count reached zero
 127 * and the inode is not hashed anywhere.  Used to clear anything
 128 * that needs to be, before the inode is completely destroyed and put
 129 * on the inode free list. We use this to drop out reference to the
 130 * lower inode.
 131 */
 132static void ecryptfs_evict_inode(struct inode *inode)
 133{
 134        truncate_inode_pages_final(&inode->i_data);
 135        clear_inode(inode);
 136        iput(ecryptfs_inode_to_lower(inode));
 137}
 138
 139/**
 140 * ecryptfs_show_options
 141 *
 142 * Prints the mount options for a given superblock.
 143 * Returns zero; does not fail.
 144 */
 145static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
 146{
 147        struct super_block *sb = root->d_sb;
 148        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 149                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 150        struct ecryptfs_global_auth_tok *walker;
 151
 152        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 153        list_for_each_entry(walker,
 154                            &mount_crypt_stat->global_auth_tok_list,
 155                            mount_crypt_stat_list) {
 156                if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 157                        seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 158                else
 159                        seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 160        }
 161        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 162
 163        seq_printf(m, ",ecryptfs_cipher=%s",
 164                mount_crypt_stat->global_default_cipher_name);
 165
 166        if (mount_crypt_stat->global_default_cipher_key_size)
 167                seq_printf(m, ",ecryptfs_key_bytes=%zd",
 168                           mount_crypt_stat->global_default_cipher_key_size);
 169        if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 170                seq_printf(m, ",ecryptfs_passthrough");
 171        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 172                seq_printf(m, ",ecryptfs_xattr_metadata");
 173        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 174                seq_printf(m, ",ecryptfs_encrypted_view");
 175        if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 176                seq_printf(m, ",ecryptfs_unlink_sigs");
 177        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 178                seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 179
 180        return 0;
 181}
 182
 183const struct super_operations ecryptfs_sops = {
 184        .alloc_inode = ecryptfs_alloc_inode,
 185        .destroy_inode = ecryptfs_destroy_inode,
 186        .statfs = ecryptfs_statfs,
 187        .remount_fs = NULL,
 188        .evict_inode = ecryptfs_evict_inode,
 189        .show_options = ecryptfs_show_options
 190};
 191