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/smp_lock.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 inode_info->lower_file = NULL; 60 inode = &inode_info->vfs_inode; 61 out: 62 return inode; 63 } 64 65 /** 66 * ecryptfs_destroy_inode 67 * @inode: The ecryptfs inode 68 * 69 * This is used during the final destruction of the inode. All 70 * allocation of memory related to the inode, including allocated 71 * memory in the crypt_stat struct, will be released here. This 72 * function also fput()'s the persistent file for the lower inode. 73 * There should be no chance that this deallocation will be missed. 74 */ 75 static void ecryptfs_destroy_inode(struct inode *inode) 76 { 77 struct ecryptfs_inode_info *inode_info; 78 79 inode_info = ecryptfs_inode_to_private(inode); 80 mutex_lock(&inode_info->lower_file_mutex); 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 mutex_unlock(&inode_info->lower_file_mutex); 93 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 94 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 95 } 96 97 /** 98 * ecryptfs_init_inode 99 * @inode: The ecryptfs inode 100 * 101 * Set up the ecryptfs inode. 102 */ 103 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 104 { 105 ecryptfs_set_inode_lower(inode, lower_inode); 106 inode->i_ino = lower_inode->i_ino; 107 inode->i_version++; 108 inode->i_op = &ecryptfs_main_iops; 109 inode->i_fop = &ecryptfs_main_fops; 110 inode->i_mapping->a_ops = &ecryptfs_aops; 111 } 112 113 /** 114 * ecryptfs_put_super 115 * @sb: Pointer to the ecryptfs super block 116 * 117 * Final actions when unmounting a file system. 118 * This will handle deallocation and release of our private data. 119 */ 120 static void ecryptfs_put_super(struct super_block *sb) 121 { 122 struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb); 123 124 lock_kernel(); 125 126 ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat); 127 kmem_cache_free(ecryptfs_sb_info_cache, sb_info); 128 ecryptfs_set_superblock_private(sb, NULL); 129 130 unlock_kernel(); 131 } 132 133 /** 134 * ecryptfs_statfs 135 * @sb: The ecryptfs super block 136 * @buf: The struct kstatfs to fill in with stats 137 * 138 * Get the filesystem statistics. Currently, we let this pass right through 139 * to the lower filesystem and take no action ourselves. 140 */ 141 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 142 { 143 return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf); 144 } 145 146 /** 147 * ecryptfs_clear_inode 148 * @inode - The ecryptfs inode 149 * 150 * Called by iput() when the inode reference count reached zero 151 * and the inode is not hashed anywhere. Used to clear anything 152 * that needs to be, before the inode is completely destroyed and put 153 * on the inode free list. We use this to drop out reference to the 154 * lower inode. 155 */ 156 static void ecryptfs_clear_inode(struct inode *inode) 157 { 158 iput(ecryptfs_inode_to_lower(inode)); 159 } 160 161 /** 162 * ecryptfs_show_options 163 * 164 * Prints the mount options for a given superblock. 165 * Returns zero; does not fail. 166 */ 167 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 168 { 169 struct super_block *sb = mnt->mnt_sb; 170 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 171 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 172 struct ecryptfs_global_auth_tok *walker; 173 174 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 175 list_for_each_entry(walker, 176 &mount_crypt_stat->global_auth_tok_list, 177 mount_crypt_stat_list) { 178 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 179 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 180 else 181 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 182 } 183 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 184 185 seq_printf(m, ",ecryptfs_cipher=%s", 186 mount_crypt_stat->global_default_cipher_name); 187 188 if (mount_crypt_stat->global_default_cipher_key_size) 189 seq_printf(m, ",ecryptfs_key_bytes=%zd", 190 mount_crypt_stat->global_default_cipher_key_size); 191 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 192 seq_printf(m, ",ecryptfs_passthrough"); 193 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 194 seq_printf(m, ",ecryptfs_xattr_metadata"); 195 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 196 seq_printf(m, ",ecryptfs_encrypted_view"); 197 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 198 seq_printf(m, ",ecryptfs_unlink_sigs"); 199 200 return 0; 201 } 202 203 const struct super_operations ecryptfs_sops = { 204 .alloc_inode = ecryptfs_alloc_inode, 205 .destroy_inode = ecryptfs_destroy_inode, 206 .drop_inode = generic_delete_inode, 207 .put_super = ecryptfs_put_super, 208 .statfs = ecryptfs_statfs, 209 .remount_fs = NULL, 210 .clear_inode = ecryptfs_clear_inode, 211 .show_options = ecryptfs_show_options 212 }; 213