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         mutex_init(&inode_info->lower_file_mutex);
  59         atomic_set(&inode_info->lower_file_count, 0);
  60         inode_info->lower_file = NULL;
  61         inode = &inode_info->vfs_inode;
  62 out:
  63         return inode;
  64 }
  65
  66 static void ecryptfs_i_callback(struct rcu_head *head)
  67 {
  68         struct inode *inode = container_of(head, struct inode, i_rcu);
  69         struct ecryptfs_inode_info *inode_info;
  70         inode_info = ecryptfs_inode_to_private(inode);
  71
  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.
  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         BUG_ON(inode_info->lower_file);
  90         ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
  91         call_rcu(&inode->i_rcu, ecryptfs_i_callback);
  92 }
  93
  94 /**
  95  * ecryptfs_statfs
  96  * @sb: The ecryptfs super block
  97  * @buf: The struct kstatfs to fill in with stats
  98  *
  99  * Get the filesystem statistics. Currently, we let this pass right through
 100  * to the lower filesystem and take no action ourselves.
 101  */
 102 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 103 {
 104         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
 105
 106         if (!lower_dentry->d_sb->s_op->statfs)
 107                 return -ENOSYS;
 108         return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
 109 }
 110
 111 /**
 112  * ecryptfs_evict_inode
 113  * @inode - The ecryptfs inode
 114  *
 115  * Called by iput() when the inode reference count reached zero
 116  * and the inode is not hashed anywhere.  Used to clear anything
 117  * that needs to be, before the inode is completely destroyed and put
 118  * on the inode free list. We use this to drop out reference to the
 119  * lower inode.
 120  */
 121 static void ecryptfs_evict_inode(struct inode *inode)
 122 {
 123         truncate_inode_pages(&inode->i_data, 0);
 124         end_writeback(inode);
 125         iput(ecryptfs_inode_to_lower(inode));
 126 }
 127
 128 /**
 129  * ecryptfs_show_options
 130  *
 131  * Prints the mount options for a given superblock.
 132  * Returns zero; does not fail.
 133  */
 134 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
 135 {
 136         struct super_block *sb = root->d_sb;
 137         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
 138                 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 139         struct ecryptfs_global_auth_tok *walker;
 140
 141         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
 142         list_for_each_entry(walker,
 143                             &mount_crypt_stat->global_auth_tok_list,
 144                             mount_crypt_stat_list) {
 145                 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
 146                         seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
 147                 else
 148                         seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
 149         }
 150         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
 151
 152         seq_printf(m, ",ecryptfs_cipher=%s",
 153                 mount_crypt_stat->global_default_cipher_name);
 154
 155         if (mount_crypt_stat->global_default_cipher_key_size)
 156                 seq_printf(m, ",ecryptfs_key_bytes=%zd",
 157                            mount_crypt_stat->global_default_cipher_key_size);
 158         if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
 159                 seq_printf(m, ",ecryptfs_passthrough");
 160         if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
 161                 seq_printf(m, ",ecryptfs_xattr_metadata");
 162         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
 163                 seq_printf(m, ",ecryptfs_encrypted_view");
 164         if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
 165                 seq_printf(m, ",ecryptfs_unlink_sigs");
 166         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
 167                 seq_printf(m, ",ecryptfs_mount_auth_tok_only");
 168
 169         return 0;
 170 }
 171
 172 const struct super_operations ecryptfs_sops = {
 173         .alloc_inode = ecryptfs_alloc_inode,
 174         .destroy_inode = ecryptfs_destroy_inode,
 175         .drop_inode = generic_drop_inode,
 176         .statfs = ecryptfs_statfs,
 177         .remount_fs = NULL,
 178         .evict_inode = ecryptfs_evict_inode,
 179         .show_options = ecryptfs_show_options
 180 };