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 <linux/statfs.h> 34 #include <linux/magic.h> 35 #include "ecryptfs_kernel.h" 36 37 struct kmem_cache *ecryptfs_inode_info_cache; 38 39 /** 40 * ecryptfs_alloc_inode - allocate an ecryptfs inode 41 * @sb: Pointer to the ecryptfs super block 42 * 43 * Called to bring an inode into existence. 44 * 45 * Only handle allocation, setting up structures should be done in 46 * ecryptfs_read_inode. This is because the kernel, between now and 47 * then, will 0 out the private data pointer. 48 * 49 * Returns a pointer to a newly allocated inode, NULL otherwise 50 */ 51 static struct inode *ecryptfs_alloc_inode(struct super_block *sb) 52 { 53 struct ecryptfs_inode_info *inode_info; 54 struct inode *inode = NULL; 55 56 inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL); 57 if (unlikely(!inode_info)) 58 goto out; 59 ecryptfs_init_crypt_stat(&inode_info->crypt_stat); 60 mutex_init(&inode_info->lower_file_mutex); 61 atomic_set(&inode_info->lower_file_count, 0); 62 inode_info->lower_file = NULL; 63 inode = &inode_info->vfs_inode; 64 out: 65 return inode; 66 } 67 68 static void ecryptfs_i_callback(struct rcu_head *head) 69 { 70 struct inode *inode = container_of(head, struct inode, i_rcu); 71 struct ecryptfs_inode_info *inode_info; 72 inode_info = ecryptfs_inode_to_private(inode); 73 74 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 75 } 76 77 /** 78 * ecryptfs_destroy_inode 79 * @inode: The ecryptfs inode 80 * 81 * This is used during the final destruction of the inode. All 82 * allocation of memory related to the inode, including allocated 83 * memory in the crypt_stat struct, will be released here. 84 * There should be no chance that this deallocation will be missed. 85 */ 86 static void ecryptfs_destroy_inode(struct inode *inode) 87 { 88 struct ecryptfs_inode_info *inode_info; 89 90 inode_info = ecryptfs_inode_to_private(inode); 91 BUG_ON(inode_info->lower_file); 92 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 93 call_rcu(&inode->i_rcu, ecryptfs_i_callback); 94 } 95 96 /** 97 * ecryptfs_statfs 98 * @sb: The ecryptfs super block 99 * @buf: The struct kstatfs to fill in with stats 100 * 101 * Get the filesystem statistics. Currently, we let this pass right through 102 * to the lower filesystem and take no action ourselves. 103 */ 104 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 105 { 106 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 107 int rc; 108 109 if (!lower_dentry->d_sb->s_op->statfs) 110 return -ENOSYS; 111 112 rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 113 if (rc) 114 return rc; 115 116 buf->f_type = ECRYPTFS_SUPER_MAGIC; 117 rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen, 118 &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat); 119 120 return rc; 121 } 122 123 /** 124 * ecryptfs_evict_inode 125 * @inode - The ecryptfs inode 126 * 127 * Called by iput() when the inode reference count reached zero 128 * and the inode is not hashed anywhere. Used to clear anything 129 * that needs to be, before the inode is completely destroyed and put 130 * on the inode free list. We use this to drop out reference to the 131 * lower inode. 132 */ 133 static void ecryptfs_evict_inode(struct inode *inode) 134 { 135 truncate_inode_pages(&inode->i_data, 0); 136 end_writeback(inode); 137 iput(ecryptfs_inode_to_lower(inode)); 138 } 139 140 /** 141 * ecryptfs_show_options 142 * 143 * Prints the mount options for a given superblock. 144 * Returns zero; does not fail. 145 */ 146 static int ecryptfs_show_options(struct seq_file *m, struct dentry *root) 147 { 148 struct super_block *sb = root->d_sb; 149 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 150 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 151 struct ecryptfs_global_auth_tok *walker; 152 153 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 154 list_for_each_entry(walker, 155 &mount_crypt_stat->global_auth_tok_list, 156 mount_crypt_stat_list) { 157 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 158 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 159 else 160 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 161 } 162 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 163 164 seq_printf(m, ",ecryptfs_cipher=%s", 165 mount_crypt_stat->global_default_cipher_name); 166 167 if (mount_crypt_stat->global_default_cipher_key_size) 168 seq_printf(m, ",ecryptfs_key_bytes=%zd", 169 mount_crypt_stat->global_default_cipher_key_size); 170 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 171 seq_printf(m, ",ecryptfs_passthrough"); 172 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 173 seq_printf(m, ",ecryptfs_xattr_metadata"); 174 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 175 seq_printf(m, ",ecryptfs_encrypted_view"); 176 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 177 seq_printf(m, ",ecryptfs_unlink_sigs"); 178 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY) 179 seq_printf(m, ",ecryptfs_mount_auth_tok_only"); 180 181 return 0; 182 } 183 184 const struct super_operations ecryptfs_sops = { 185 .alloc_inode = ecryptfs_alloc_inode, 186 .destroy_inode = ecryptfs_destroy_inode, 187 .drop_inode = generic_drop_inode, 188 .statfs = ecryptfs_statfs, 189 .remount_fs = NULL, 190 .evict_inode = ecryptfs_evict_inode, 191 .show_options = ecryptfs_show_options 192 }; 193