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/seq_file.h>
  30 #include <linux/smp_lock.h>
  31 #include <linux/file.h>
  32 #include <linux/crypto.h>
  33 #include "ecryptfs_kernel.h"
  34
  35 struct 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  */
  49 static 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;
  61 out:
  62         return inode;
  63 }
  64
  65 /**
  66  * ecryptfs_destroy_inode
  67  * @inode: The ecryptfs inode
  68  *
  69  * This is used during the final destruction of the inode.  All
  70  * allocation of memory related to the inode, including allocated
  71  * memory in the crypt_stat struct, will be released here. This
  72  * function also fput()'s the persistent file for the lower inode.
  73  * There should be no chance that this deallocation will be missed.
  74  */
  75 static void ecryptfs_destroy_inode(struct inode *inode)
  76 {
  77         struct ecryptfs_inode_info *inode_info;
  78
  79         inode_info = ecryptfs_inode_to_private(inode);
  80         mutex_lock(&inode_info->lower_file_mutex);
  81         if (inode_info->lower_file) {
  82                 struct dentry *lower_dentry =
  83                         inode_info->lower_file->f_dentry;
  84
  85                 BUG_ON(!lower_dentry);
  86                 if (lower_dentry->d_inode) {
  87                         fput(inode_info->lower_file);
  88                         inode_info->lower_file = NULL;
  89                         d_drop(lower_dentry);
  90                 }
  91         }
  92         mutex_unlock(&inode_info->lower_file_mutex);
  93         ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  94         kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
  95 }
  96
  97 /**
  98  * ecryptfs_init_inode
  99  * @inode: The ecryptfs inode
 100  *
 101  * Set up the ecryptfs inode.
 102  */
 103 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode)
 104 {
 105         ecryptfs_set_inode_lower(inode, lower_inode);
 106         inode->i_ino = lower_inode->i_ino;
 107         inode->i_version++;
 108         inode->i_op = &ecryptfs_main_iops;
 109         inode->i_fop = &ecryptfs_main_fops;
 110         inode->i_mapping->a_ops = &ecryptfs_aops;
 111 }
 112
 113 /**
 114  * ecryptfs_put_super
 115  * @sb: Pointer to the ecryptfs super block
 116  *
 117  * Final actions when unmounting a file system.
 118  * This will handle deallocation and release of our private data.
 119  */
 120 static void ecryptfs_put_super(struct super_block *sb)
 121 {
 122         struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb);
 123
 124         lock_kernel();
 125
 126         ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
 127         kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
 128         ecryptfs_set_superblock_private(sb, NULL);
 129
 130         unlock_kernel();
 131 }
 132
 133 /**
 134  * ecryptfs_statfs
 135  * @sb: The ecryptfs super block
 136  * @buf: The struct kstatfs to fill in with stats
 137  *
 138  * Get the filesystem statistics. Currently, we let this pass right through
 139  * to the lower filesystem and take no action ourselves.
 140  */
 141 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 142 {
 143         return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf);
 144 }
 145
 146 /**
 147  * ecryptfs_clear_inode
 148  * @inode - The ecryptfs inode
 149  *
 150  * Called by iput() when the inode reference count reached zero
 151  * and the inode is not hashed anywhere.  Used to clear anything
 152  * that needs to be, before the inode is completely destroyed and put
 153  * on the inode free list. We use this to drop out reference to the
 154  * lower inode.
 155  */
 156 static void ecryptfs_clear_inode(struct inode *inode)
 157 {
 158         iput(ecryptfs_inode_to_lower(inode));
 159 }
 160
 161 /**
 162  * ecryptfs_show_options
 163  *
 164  * Prints the mount options for a given superblock.
 165  * Returns zero; does not fail.
 166  */
 167 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 168 {
 169         struct super_block *sb = mnt->mnt_sb;
 170         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 171                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 172         struct ecryptfs_global_auth_tok *walker;
 173
 174         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 175         list_for_each_entry(walker,
 176                             &mount_crypt_stat->global_auth_tok_list,
 177                             mount_crypt_stat_list) {
 178                 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 179                         seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 180                 else
 181                         seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 182         }
 183         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 184
 185         seq_printf(m, ",ecryptfs_cipher=%s",
 186                 mount_crypt_stat->global_default_cipher_name);
 187
 188         if (mount_crypt_stat->global_default_cipher_key_size)
 189                 seq_printf(m, ",ecryptfs_key_bytes=%zd",
 190                            mount_crypt_stat->global_default_cipher_key_size);
 191         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 192                 seq_printf(m, ",ecryptfs_passthrough");
 193         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 194                 seq_printf(m, ",ecryptfs_xattr_metadata");
 195         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 196                 seq_printf(m, ",ecryptfs_encrypted_view");
 197         if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 198                 seq_printf(m, ",ecryptfs_unlink_sigs");
 199
 200         return 0;
 201 }
 202
 203 const struct super_operations ecryptfs_sops = {
 204         .alloc_inode = ecryptfs_alloc_inode,
 205         .destroy_inode = ecryptfs_destroy_inode,
 206         .drop_inode = generic_delete_inode,
 207         .put_super = ecryptfs_put_super,
 208         .statfs = ecryptfs_statfs,
 209         .remount_fs = NULL,
 210         .clear_inode = ecryptfs_clear_inode,
 211         .show_options = ecryptfs_show_options
 212 };