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/file.h>
  31 #include <linux/crypto.h>
  32 #include "ecryptfs_kernel.h"
  33
  34 struct kmem_cache *ecryptfs_inode_info_cache;
  35
  36 /**
  37  * ecryptfs_alloc_inode - allocate an ecryptfs inode
  38  * @sb: Pointer to the ecryptfs super block
  39  *
  40  * Called to bring an inode into existence.
  41  *
  42  * Only handle allocation, setting up structures should be done in
  43  * ecryptfs_read_inode. This is because the kernel, between now and
  44  * then, will 0 out the private data pointer.
  45  *
  46  * Returns a pointer to a newly allocated inode, NULL otherwise
  47  */
  48 static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
  49 {
  50         struct ecryptfs_inode_info *inode_info;
  51         struct inode *inode = NULL;
  52
  53         inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL);
  54         if (unlikely(!inode_info))
  55                 goto out;
  56         ecryptfs_init_crypt_stat(&inode_info->crypt_stat);
  57         mutex_init(&inode_info->lower_file_mutex);
  58         inode_info->lower_file = NULL;
  59         inode = &inode_info->vfs_inode;
  60 out:
  61         return inode;
  62 }
  63
  64 /**
  65  * ecryptfs_destroy_inode
  66  * @inode: The ecryptfs inode
  67  *
  68  * This is used during the final destruction of the inode.  All
  69  * allocation of memory related to the inode, including allocated
  70  * memory in the crypt_stat struct, will be released here. This
  71  * function also fput()'s the persistent file for the lower inode.
  72  * There should be no chance that this deallocation will be missed.
  73  */
  74 static void ecryptfs_destroy_inode(struct inode *inode)
  75 {
  76         struct ecryptfs_inode_info *inode_info;
  77
  78         inode_info = ecryptfs_inode_to_private(inode);
  79         mutex_lock(&inode_info->lower_file_mutex);
  80         if (inode_info->lower_file) {
  81                 struct dentry *lower_dentry =
  82                         inode_info->lower_file->f_dentry;
  83
  84                 BUG_ON(!lower_dentry);
  85                 if (lower_dentry->d_inode) {
  86                         fput(inode_info->lower_file);
  87                         inode_info->lower_file = NULL;
  88                         d_drop(lower_dentry);
  89                 }
  90         }
  91         mutex_unlock(&inode_info->lower_file_mutex);
  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         ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat);
 124         kmem_cache_free(ecryptfs_sb_info_cache, sb_info);
 125         ecryptfs_set_superblock_private(sb, NULL);
 126 }
 127
 128 /**
 129  * ecryptfs_statfs
 130  * @sb: The ecryptfs super block
 131  * @buf: The struct kstatfs to fill in with stats
 132  *
 133  * Get the filesystem statistics. Currently, we let this pass right through
 134  * to the lower filesystem and take no action ourselves.
 135  */
 136 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 137 {
 138         return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf);
 139 }
 140
 141 /**
 142  * ecryptfs_clear_inode
 143  * @inode - The ecryptfs inode
 144  *
 145  * Called by iput() when the inode reference count reached zero
 146  * and the inode is not hashed anywhere.  Used to clear anything
 147  * that needs to be, before the inode is completely destroyed and put
 148  * on the inode free list. We use this to drop out reference to the
 149  * lower inode.
 150  */
 151 static void ecryptfs_clear_inode(struct inode *inode)
 152 {
 153         iput(ecryptfs_inode_to_lower(inode));
 154 }
 155
 156 /**
 157  * ecryptfs_show_options
 158  *
 159  * Prints the directory we are currently mounted over.
 160  * Returns zero on success; non-zero otherwise
 161  */
 162 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt)
 163 {
 164         struct super_block *sb = mnt->mnt_sb;
 165         struct dentry *lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root);
 166         struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(sb->s_root);
 167         char *tmp_page;
 168         char *path;
 169         int rc = 0;
 170
 171         tmp_page = (char *)__get_free_page(GFP_KERNEL);
 172         if (!tmp_page) {
 173                 rc = -ENOMEM;
 174                 goto out;
 175         }
 176         path = d_path(lower_root_dentry, lower_mnt, tmp_page, PAGE_SIZE);
 177         if (IS_ERR(path)) {
 178                 rc = PTR_ERR(path);
 179                 goto out;
 180         }
 181         seq_printf(m, ",dir=%s", path);
 182         free_page((unsigned long)tmp_page);
 183 out:
 184         return rc;
 185 }
 186
 187 const struct super_operations ecryptfs_sops = {
 188         .alloc_inode = ecryptfs_alloc_inode,
 189         .destroy_inode = ecryptfs_destroy_inode,
 190         .drop_inode = generic_delete_inode,
 191         .put_super = ecryptfs_put_super,
 192         .statfs = ecryptfs_statfs,
 193         .remount_fs = NULL,
 194         .clear_inode = ecryptfs_clear_inode,
 195         .show_options = ecryptfs_show_options
 196 };