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 atomic_set(&inode_info->lower_file_count, 0); 60 inode_info->lower_file = NULL; 61 inode = &inode_info->vfs_inode; 62 out: 63 return inode; 64 } 65 66 static void ecryptfs_i_callback(struct rcu_head *head) 67 { 68 struct inode *inode = container_of(head, struct inode, i_rcu); 69 struct ecryptfs_inode_info *inode_info; 70 inode_info = ecryptfs_inode_to_private(inode); 71 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. 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 BUG_ON(inode_info->lower_file); 90 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 91 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 92 } 93 94 /** 95 * ecryptfs_statfs 96 * @sb: The ecryptfs super block 97 * @buf: The struct kstatfs to fill in with stats 98 * 99 * Get the filesystem statistics. Currently, we let this pass right through 100 * to the lower filesystem and take no action ourselves. 101 */ 102 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 103 { 104 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 105 106 if (!lower_dentry->d_sb->s_op->statfs) 107 return -ENOSYS; 108 return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 109 } 110 111 /** 112 * ecryptfs_evict_inode 113 * @inode - The ecryptfs inode 114 * 115 * Called by iput() when the inode reference count reached zero 116 * and the inode is not hashed anywhere. Used to clear anything 117 * that needs to be, before the inode is completely destroyed and put 118 * on the inode free list. We use this to drop out reference to the 119 * lower inode. 120 */ 121 static void ecryptfs_evict_inode(struct inode *inode) 122 { 123 truncate_inode_pages(&inode->i_data, 0); 124 end_writeback(inode); 125 iput(ecryptfs_inode_to_lower(inode)); 126 } 127 128 /** 129 * ecryptfs_show_options 130 * 131 * Prints the mount options for a given superblock. 132 * Returns zero; does not fail. 133 */ 134 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root) 135 { 136 struct super_block *sb = root->d_sb; 137 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 138 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 139 struct ecryptfs_global_auth_tok *walker; 140 141 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 142 list_for_each_entry(walker, 143 &mount_crypt_stat->global_auth_tok_list, 144 mount_crypt_stat_list) { 145 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 146 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 147 else 148 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 149 } 150 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 151 152 seq_printf(m, ",ecryptfs_cipher=%s", 153 mount_crypt_stat->global_default_cipher_name); 154 155 if (mount_crypt_stat->global_default_cipher_key_size) 156 seq_printf(m, ",ecryptfs_key_bytes=%zd", 157 mount_crypt_stat->global_default_cipher_key_size); 158 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 159 seq_printf(m, ",ecryptfs_passthrough"); 160 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 161 seq_printf(m, ",ecryptfs_xattr_metadata"); 162 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 163 seq_printf(m, ",ecryptfs_encrypted_view"); 164 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 165 seq_printf(m, ",ecryptfs_unlink_sigs"); 166 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 167 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 168 169 return 0; 170 } 171 172 const struct super_operations ecryptfs_sops = { 173 .alloc_inode = ecryptfs_alloc_inode, 174 .destroy_inode = ecryptfs_destroy_inode, 175 .drop_inode = generic_drop_inode, 176 .statfs = ecryptfs_statfs, 177 .remount_fs = NULL, 178 .evict_inode = ecryptfs_evict_inode, 179 .show_options = ecryptfs_show_options 180 }; 181