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