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