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 inode_info->lower_file = NULL; 59 inode = &inode_info->vfs_inode; 60 out: 61 return inode; 62 } 63 64 static void ecryptfs_i_callback(struct rcu_head *head) 65 { 66 struct inode *inode = container_of(head, struct inode, i_rcu); 67 struct ecryptfs_inode_info *inode_info; 68 inode_info = ecryptfs_inode_to_private(inode); 69 70 INIT_LIST_HEAD(&inode->i_dentry); 71 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 72 } 73 74 /** 75 * ecryptfs_destroy_inode 76 * @inode: The ecryptfs inode 77 * 78 * This is used during the final destruction of the inode. All 79 * allocation of memory related to the inode, including allocated 80 * memory in the crypt_stat struct, will be released here. This 81 * function also fput()'s the persistent file for the lower inode. 82 * There should be no chance that this deallocation will be missed. 83 */ 84 static void ecryptfs_destroy_inode(struct inode *inode) 85 { 86 struct ecryptfs_inode_info *inode_info; 87 88 inode_info = ecryptfs_inode_to_private(inode); 89 if (inode_info->lower_file) { 90 struct dentry *lower_dentry = 91 inode_info->lower_file->f_dentry; 92 93 BUG_ON(!lower_dentry); 94 if (lower_dentry->d_inode) { 95 fput(inode_info->lower_file); 96 inode_info->lower_file = NULL; 97 } 98 } 99 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 100 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 101 } 102 103 /** 104 * ecryptfs_init_inode 105 * @inode: The ecryptfs inode 106 * 107 * Set up the ecryptfs inode. 108 */ 109 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 110 { 111 ecryptfs_set_inode_lower(inode, lower_inode); 112 inode->i_ino = lower_inode->i_ino; 113 inode->i_version++; 114 inode->i_op = &ecryptfs_main_iops; 115 inode->i_fop = &ecryptfs_main_fops; 116 inode->i_mapping->a_ops = &ecryptfs_aops; 117 } 118 119 /** 120 * ecryptfs_statfs 121 * @sb: The ecryptfs super block 122 * @buf: The struct kstatfs to fill in with stats 123 * 124 * Get the filesystem statistics. Currently, we let this pass right through 125 * to the lower filesystem and take no action ourselves. 126 */ 127 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 128 { 129 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 130 131 if (!lower_dentry->d_sb->s_op->statfs) 132 return -ENOSYS; 133 return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 134 } 135 136 /** 137 * ecryptfs_evict_inode 138 * @inode - The ecryptfs inode 139 * 140 * Called by iput() when the inode reference count reached zero 141 * and the inode is not hashed anywhere. Used to clear anything 142 * that needs to be, before the inode is completely destroyed and put 143 * on the inode free list. We use this to drop out reference to the 144 * lower inode. 145 */ 146 static void ecryptfs_evict_inode(struct inode *inode) 147 { 148 truncate_inode_pages(&inode->i_data, 0); 149 end_writeback(inode); 150 iput(ecryptfs_inode_to_lower(inode)); 151 } 152 153 /** 154 * ecryptfs_show_options 155 * 156 * Prints the mount options for a given superblock. 157 * Returns zero; does not fail. 158 */ 159 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 160 { 161 struct super_block *sb = mnt->mnt_sb; 162 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 163 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 164 struct ecryptfs_global_auth_tok *walker; 165 166 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 167 list_for_each_entry(walker, 168 &mount_crypt_stat->global_auth_tok_list, 169 mount_crypt_stat_list) { 170 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 171 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 172 else 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 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 190 seq_printf(m, ",ecryptfs_unlink_sigs"); 191 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 192 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 193 194 return 0; 195 } 196 197 const struct super_operations ecryptfs_sops = { 198 .alloc_inode = ecryptfs_alloc_inode, 199 .destroy_inode = ecryptfs_destroy_inode, 200 .drop_inode = generic_drop_inode, 201 .statfs = ecryptfs_statfs, 202 .remount_fs = NULL, 203 .evict_inode = ecryptfs_evict_inode, 204 .show_options = ecryptfs_show_options 205 }; 206