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 <linux/statfs.h>
  34 #include <linux/magic.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 struct 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  */
  51 static 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;
  64 out:
  65         return inode;
  66 }
  67
  68 static 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  */
  86 static 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  */
 104 static 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  */
 133 static 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  */
 146 static 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
 184 const 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 };