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/statfs.h> 33 #include <linux/magic.h> 34 #include "ecryptfs_kernel.h" 35 36 struct kmem_cache *ecryptfs_inode_info_cache; 37 38 /** 39 * ecryptfs_alloc_inode - allocate an ecryptfs inode 40 * @sb: Pointer to the ecryptfs super block 41 * 42 * Called to bring an inode into existence. 43 * 44 * Only handle allocation, setting up structures should be done in 45 * ecryptfs_read_inode. This is because the kernel, between now and 46 * then, will 0 out the private data pointer. 47 * 48 * Returns a pointer to a newly allocated inode, NULL otherwise 49 */ 50 static struct inode *ecryptfs_alloc_inode(struct super_block *sb) 51 { 52 struct ecryptfs_inode_info *inode_info; 53 struct inode *inode = NULL; 54 55 inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL); 56 if (unlikely(!inode_info)) 57 goto out; 58 ecryptfs_init_crypt_stat(&inode_info->crypt_stat); 59 mutex_init(&inode_info->lower_file_mutex); 60 atomic_set(&inode_info->lower_file_count, 0); 61 inode_info->lower_file = NULL; 62 inode = &inode_info->vfs_inode; 63 out: 64 return inode; 65 } 66 67 static void ecryptfs_i_callback(struct rcu_head *head) 68 { 69 struct inode *inode = container_of(head, struct inode, i_rcu); 70 struct ecryptfs_inode_info *inode_info; 71 inode_info = ecryptfs_inode_to_private(inode); 72 73 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 74 } 75 76 /** 77 * ecryptfs_destroy_inode 78 * @inode: The ecryptfs inode 79 * 80 * This is used during the final destruction of the inode. All 81 * allocation of memory related to the inode, including allocated 82 * memory in the crypt_stat struct, will be released here. 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 BUG_ON(inode_info->lower_file); 91 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 92 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 93 } 94 95 /** 96 * ecryptfs_statfs 97 * @sb: The ecryptfs super block 98 * @buf: The struct kstatfs to fill in with stats 99 * 100 * Get the filesystem statistics. Currently, we let this pass right through 101 * to the lower filesystem and take no action ourselves. 102 */ 103 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 104 { 105 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 106 int rc; 107 108 if (!lower_dentry->d_sb->s_op->statfs) 109 return -ENOSYS; 110 111 rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 112 if (rc) 113 return rc; 114 115 buf->f_type = ECRYPTFS_SUPER_MAGIC; 116 rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen, 117 &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat); 118 119 return rc; 120 } 121 122 /** 123 * ecryptfs_evict_inode 124 * @inode - The ecryptfs inode 125 * 126 * Called by iput() when the inode reference count reached zero 127 * and the inode is not hashed anywhere. Used to clear anything 128 * that needs to be, before the inode is completely destroyed and put 129 * on the inode free list. We use this to drop out reference to the 130 * lower inode. 131 */ 132 static void ecryptfs_evict_inode(struct inode *inode) 133 { 134 truncate_inode_pages_final(&inode->i_data); 135 clear_inode(inode); 136 iput(ecryptfs_inode_to_lower(inode)); 137 } 138 139 /** 140 * ecryptfs_show_options 141 * 142 * Prints the mount options for a given superblock. 143 * Returns zero; does not fail. 144 */ 145 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root) 146 { 147 struct super_block *sb = root->d_sb; 148 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 149 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 150 struct ecryptfs_global_auth_tok *walker; 151 152 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 153 list_for_each_entry(walker, 154 &mount_crypt_stat->global_auth_tok_list, 155 mount_crypt_stat_list) { 156 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 157 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 158 else 159 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 160 } 161 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 162 163 seq_printf(m, ",ecryptfs_cipher=%s", 164 mount_crypt_stat->global_default_cipher_name); 165 166 if (mount_crypt_stat->global_default_cipher_key_size) 167 seq_printf(m, ",ecryptfs_key_bytes=%zd", 168 mount_crypt_stat->global_default_cipher_key_size); 169 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 170 seq_printf(m, ",ecryptfs_passthrough"); 171 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 172 seq_printf(m, ",ecryptfs_xattr_metadata"); 173 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 174 seq_printf(m, ",ecryptfs_encrypted_view"); 175 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 176 seq_printf(m, ",ecryptfs_unlink_sigs"); 177 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 178 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 179 180 return 0; 181 } 182 183 const struct super_operations ecryptfs_sops = { 184 .alloc_inode = ecryptfs_alloc_inode, 185 .destroy_inode = ecryptfs_destroy_inode, 186 .statfs = ecryptfs_statfs, 187 .remount_fs = NULL, 188 .evict_inode = ecryptfs_evict_inode, 189 .show_options = ecryptfs_show_options 190 }; 191