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 if (ecryptfs_init_crypt_stat(&inode_info->crypt_stat)) { 59 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 60 goto out; 61 } 62 mutex_init(&inode_info->lower_file_mutex); 63 atomic_set(&inode_info->lower_file_count, 0); 64 inode_info->lower_file = NULL; 65 inode = &inode_info->vfs_inode; 66 out: 67 return inode; 68 } 69 70 static void ecryptfs_i_callback(struct rcu_head *head) 71 { 72 struct inode *inode = container_of(head, struct inode, i_rcu); 73 struct ecryptfs_inode_info *inode_info; 74 inode_info = ecryptfs_inode_to_private(inode); 75 76 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 77 } 78 79 /** 80 * ecryptfs_destroy_inode 81 * @inode: The ecryptfs inode 82 * 83 * This is used during the final destruction of the inode. All 84 * allocation of memory related to the inode, including allocated 85 * memory in the crypt_stat struct, will be released here. 86 * There should be no chance that this deallocation will be missed. 87 */ 88 static void ecryptfs_destroy_inode(struct inode *inode) 89 { 90 struct ecryptfs_inode_info *inode_info; 91 92 inode_info = ecryptfs_inode_to_private(inode); 93 BUG_ON(inode_info->lower_file); 94 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 95 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 96 } 97 98 /** 99 * ecryptfs_statfs 100 * @sb: The ecryptfs super block 101 * @buf: The struct kstatfs to fill in with stats 102 * 103 * Get the filesystem statistics. Currently, we let this pass right through 104 * to the lower filesystem and take no action ourselves. 105 */ 106 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 107 { 108 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 109 int rc; 110 111 if (!lower_dentry->d_sb->s_op->statfs) 112 return -ENOSYS; 113 114 rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 115 if (rc) 116 return rc; 117 118 buf->f_type = ECRYPTFS_SUPER_MAGIC; 119 rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen, 120 &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat); 121 122 return rc; 123 } 124 125 /** 126 * ecryptfs_evict_inode 127 * @inode - The ecryptfs inode 128 * 129 * Called by iput() when the inode reference count reached zero 130 * and the inode is not hashed anywhere. Used to clear anything 131 * that needs to be, before the inode is completely destroyed and put 132 * on the inode free list. We use this to drop out reference to the 133 * lower inode. 134 */ 135 static void ecryptfs_evict_inode(struct inode *inode) 136 { 137 truncate_inode_pages_final(&inode->i_data); 138 clear_inode(inode); 139 iput(ecryptfs_inode_to_lower(inode)); 140 } 141 142 /** 143 * ecryptfs_show_options 144 * 145 * Prints the mount options for a given superblock. 146 * Returns zero; does not fail. 147 */ 148 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root) 149 { 150 struct super_block *sb = root->d_sb; 151 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 152 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 153 struct ecryptfs_global_auth_tok *walker; 154 155 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 156 list_for_each_entry(walker, 157 &mount_crypt_stat->global_auth_tok_list, 158 mount_crypt_stat_list) { 159 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 160 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 161 else 162 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 163 } 164 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 165 166 seq_printf(m, ",ecryptfs_cipher=%s", 167 mount_crypt_stat->global_default_cipher_name); 168 169 if (mount_crypt_stat->global_default_cipher_key_size) 170 seq_printf(m, ",ecryptfs_key_bytes=%zd", 171 mount_crypt_stat->global_default_cipher_key_size); 172 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 173 seq_printf(m, ",ecryptfs_passthrough"); 174 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 175 seq_printf(m, ",ecryptfs_xattr_metadata"); 176 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 177 seq_printf(m, ",ecryptfs_encrypted_view"); 178 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 179 seq_printf(m, ",ecryptfs_unlink_sigs"); 180 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 181 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 182 183 return 0; 184 } 185 186 const struct super_operations ecryptfs_sops = { 187 .alloc_inode = ecryptfs_alloc_inode, 188 .destroy_inode = ecryptfs_destroy_inode, 189 .statfs = ecryptfs_statfs, 190 .remount_fs = NULL, 191 .evict_inode = ecryptfs_evict_inode, 192 .show_options = ecryptfs_show_options 193 }; 194