linux/fs/ecryptfs/super.c
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   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 <linux/statfs.h>
  34#include <linux/magic.h>
  35#include "ecryptfs_kernel.h"
  36
  37struct kmem_cache *ecryptfs_inode_info_cache;
  38
  39/**
  40 * ecryptfs_alloc_inode - allocate an ecryptfs inode
  41 * @sb: Pointer to the ecryptfs super block
  42 *
  43 * Called to bring an inode into existence.
  44 *
  45 * Only handle allocation, setting up structures should be done in
  46 * ecryptfs_read_inode. This is because the kernel, between now and
  47 * then, will 0 out the private data pointer.
  48 *
  49 * Returns a pointer to a newly allocated inode, NULL otherwise
  50 */
  51static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
  52{
  53        struct ecryptfs_inode_info *inode_info;
  54        struct inode *inode = NULL;
  55
  56        inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  57        if (unlikely(!inode_info))
  58                goto out;
  59        ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
  60        mutex_init(&inode_info->lower_file_mutex);
  61        atomic_set(&inode_info->lower_file_count, 0);
  62        inode_info->lower_file = NULL;
  63        inode = &inode_info->vfs_inode;
  64out:
  65        return inode;
  66}
  67
  68static void ecryptfs_i_callback(struct rcu_head *head)
  69{
  70        struct inode *inode = container_of(head, struct inode, i_rcu);
  71        struct ecryptfs_inode_info *inode_info;
  72        inode_info = ecryptfs_inode_to_private(inode);
  73
  74        kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  75}
  76
  77/**
  78 * ecryptfs_destroy_inode
  79 * @inode: The ecryptfs inode
  80 *
  81 * This is used during the final destruction of the inode.  All
  82 * allocation of memory related to the inode, including allocated
  83 * memory in the crypt_stat struct, will be released here.
  84 * There should be no chance that this deallocation will be missed.
  85 */
  86static void ecryptfs_destroy_inode(struct inode *inode)
  87{
  88        struct ecryptfs_inode_info *inode_info;
  89
  90        inode_info = ecryptfs_inode_to_private(inode);
  91        BUG_ON(inode_info->lower_file);
  92        ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  93        call_rcu(&inode->i_rcu, ecryptfs_i_callback);
  94}
  95
  96/**
  97 * ecryptfs_statfs
  98 * @sb: The ecryptfs super block
  99 * @buf: The struct kstatfs to fill in with stats
 100 *
 101 * Get the filesystem statistics. Currently, we let this pass right through
 102 * to the lower filesystem and take no action ourselves.
 103 */
 104static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 105{
 106        struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 107        int rc;
 108
 109        if (!lower_dentry->d_sb->s_op->statfs)
 110                return -ENOSYS;
 111
 112        rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 113        if (rc)
 114                return rc;
 115
 116        buf->f_type = ECRYPTFS_SUPER_MAGIC;
 117        rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
 118               &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
 119
 120        return rc;
 121}
 122
 123/**
 124 * ecryptfs_evict_inode
 125 * @inode - The ecryptfs inode
 126 *
 127 * Called by iput() when the inode reference count reached zero
 128 * and the inode is not hashed anywhere.  Used to clear anything
 129 * that needs to be, before the inode is completely destroyed and put
 130 * on the inode free list. We use this to drop out reference to the
 131 * lower inode.
 132 */
 133static void ecryptfs_evict_inode(struct inode *inode)
 134{
 135        truncate_inode_pages(&inode->i_data, 0);
 136        clear_inode(inode);
 137        iput(ecryptfs_inode_to_lower(inode));
 138}
 139
 140/**
 141 * ecryptfs_show_options
 142 *
 143 * Prints the mount options for a given superblock.
 144 * Returns zero; does not fail.
 145 */
 146static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
 147{
 148        struct super_block *sb = root->d_sb;
 149        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 150                &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 151        struct ecryptfs_global_auth_tok *walker;
 152
 153        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 154        list_for_each_entry(walker,
 155                            &mount_crypt_stat->global_auth_tok_list,
 156                            mount_crypt_stat_list) {
 157                if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 158                        seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 159                else
 160                        seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 161        }
 162        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 163
 164        seq_printf(m, ",ecryptfs_cipher=%s",
 165                mount_crypt_stat->global_default_cipher_name);
 166
 167        if (mount_crypt_stat->global_default_cipher_key_size)
 168                seq_printf(m, ",ecryptfs_key_bytes=%zd",
 169                           mount_crypt_stat->global_default_cipher_key_size);
 170        if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 171                seq_printf(m, ",ecryptfs_passthrough");
 172        if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 173                seq_printf(m, ",ecryptfs_xattr_metadata");
 174        if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 175                seq_printf(m, ",ecryptfs_encrypted_view");
 176        if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 177                seq_printf(m, ",ecryptfs_unlink_sigs");
 178        if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 179                seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 180
 181        return 0;
 182}
 183
 184const struct super_operations ecryptfs_sops = {
 185        .alloc_inode = ecryptfs_alloc_inode,
 186        .destroy_inode = ecryptfs_destroy_inode,
 187        .statfs = ecryptfs_statfs,
 188        .remount_fs = NULL,
 189        .evict_inode = ecryptfs_evict_inode,
 190        .show_options = ecryptfs_show_options
 191};
 192
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