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 "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 static void ecryptfs_i_callback(struct rcu_head *head) 66 { 67 struct inode *inode = container_of(head, struct inode, i_rcu); 68 struct ecryptfs_inode_info *inode_info; 69 inode_info = ecryptfs_inode_to_private(inode); 70 71 INIT_LIST_HEAD(&inode->i_dentry); 72 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 73 } 74 75 /** 76 * ecryptfs_destroy_inode 77 * @inode: The ecryptfs inode 78 * 79 * This is used during the final destruction of the inode. All 80 * allocation of memory related to the inode, including allocated 81 * memory in the crypt_stat struct, will be released here. This 82 * function also fput()'s the persistent file for the lower inode. 83 * There should be no chance that this deallocation will be missed. 84 */ 85 static void ecryptfs_destroy_inode(struct inode *inode) 86 { 87 struct ecryptfs_inode_info *inode_info; 88 89 inode_info = ecryptfs_inode_to_private(inode); 90 if (inode_info->lower_file) { 91 struct dentry *lower_dentry = 92 inode_info->lower_file->f_dentry; 93 94 BUG_ON(!lower_dentry); 95 if (lower_dentry->d_inode) { 96 fput(inode_info->lower_file); 97 inode_info->lower_file = NULL; 98 } 99 } 100 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 101 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 102 } 103 104 /** 105 * ecryptfs_init_inode 106 * @inode: The ecryptfs inode 107 * 108 * Set up the ecryptfs inode. 109 */ 110 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 111 { 112 ecryptfs_set_inode_lower(inode, lower_inode); 113 inode->i_ino = lower_inode->i_ino; 114 inode->i_version++; 115 inode->i_op = &ecryptfs_main_iops; 116 inode->i_fop = &ecryptfs_main_fops; 117 inode->i_mapping->a_ops = &ecryptfs_aops; 118 } 119 120 /** 121 * ecryptfs_statfs 122 * @sb: The ecryptfs super block 123 * @buf: The struct kstatfs to fill in with stats 124 * 125 * Get the filesystem statistics. Currently, we let this pass right through 126 * to the lower filesystem and take no action ourselves. 127 */ 128 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 129 { 130 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 131 132 if (!lower_dentry->d_sb->s_op->statfs) 133 return -ENOSYS; 134 return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 135 } 136 137 /** 138 * ecryptfs_evict_inode 139 * @inode - The ecryptfs inode 140 * 141 * Called by iput() when the inode reference count reached zero 142 * and the inode is not hashed anywhere. Used to clear anything 143 * that needs to be, before the inode is completely destroyed and put 144 * on the inode free list. We use this to drop out reference to the 145 * lower inode. 146 */ 147 static void ecryptfs_evict_inode(struct inode *inode) 148 { 149 truncate_inode_pages(&inode->i_data, 0); 150 end_writeback(inode); 151 iput(ecryptfs_inode_to_lower(inode)); 152 } 153 154 /** 155 * ecryptfs_show_options 156 * 157 * Prints the mount options for a given superblock. 158 * Returns zero; does not fail. 159 */ 160 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 161 { 162 struct super_block *sb = mnt->mnt_sb; 163 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 164 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 165 struct ecryptfs_global_auth_tok *walker; 166 167 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 168 list_for_each_entry(walker, 169 &mount_crypt_stat->global_auth_tok_list, 170 mount_crypt_stat_list) { 171 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 172 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 173 else 174 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 175 } 176 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 177 178 seq_printf(m, ",ecryptfs_cipher=%s", 179 mount_crypt_stat->global_default_cipher_name); 180 181 if (mount_crypt_stat->global_default_cipher_key_size) 182 seq_printf(m, ",ecryptfs_key_bytes=%zd", 183 mount_crypt_stat->global_default_cipher_key_size); 184 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 185 seq_printf(m, ",ecryptfs_passthrough"); 186 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 187 seq_printf(m, ",ecryptfs_xattr_metadata"); 188 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 189 seq_printf(m, ",ecryptfs_encrypted_view"); 190 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 191 seq_printf(m, ",ecryptfs_unlink_sigs"); 192 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 193 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 194 195 return 0; 196 } 197 198 const struct super_operations ecryptfs_sops = { 199 .alloc_inode = ecryptfs_alloc_inode, 200 .destroy_inode = ecryptfs_destroy_inode, 201 .drop_inode = generic_delete_inode, 202 .statfs = ecryptfs_statfs, 203 .remount_fs = NULL, 204 .evict_inode = ecryptfs_evict_inode, 205 .show_options = ecryptfs_show_options 206 }; 207