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 mount options for a given superblock. 160 * Returns zero; does not fail. 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 ecryptfs_mount_crypt_stat *mount_crypt_stat = 166 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 167 struct ecryptfs_global_auth_tok *walker; 168 169 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 170 list_for_each_entry(walker, 171 &mount_crypt_stat->global_auth_tok_list, 172 mount_crypt_stat_list) { 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"); 189 190 return 0; 191 } 192 193 const struct super_operations ecryptfs_sops = { 194 .alloc_inode = ecryptfs_alloc_inode, 195 .destroy_inode = ecryptfs_destroy_inode, 196 .drop_inode = generic_delete_inode, 197 .put_super = ecryptfs_put_super, 198 .statfs = ecryptfs_statfs, 199 .remount_fs = NULL, 200 .clear_inode = ecryptfs_clear_inode, 201 .show_options = ecryptfs_show_options 202 }; 203