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/smp_lock.h> 32#include <linux/file.h> 33#include <linux/crypto.h> 34#include "ecryptfs_kernel.h" 35 36struct 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 */ 50static 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 inode_info->lower_file = NULL; 61 inode = &inode_info->vfs_inode; 62out: 63 return inode; 64} 65 66/** 67 * ecryptfs_destroy_inode 68 * @inode: The ecryptfs inode 69 * 70 * This is used during the final destruction of the inode. All 71 * allocation of memory related to the inode, including allocated 72 * memory in the crypt_stat struct, will be released here. This 73 * function also fput()'s the persistent file for the lower inode. 74 * There should be no chance that this deallocation will be missed. 75 */ 76static void ecryptfs_destroy_inode(struct inode *inode) 77{ 78 struct ecryptfs_inode_info *inode_info; 79 80 inode_info = ecryptfs_inode_to_private(inode); 81 if (inode_info->lower_file) { 82 struct dentry *lower_dentry = 83 inode_info->lower_file->f_dentry; 84 85 BUG_ON(!lower_dentry); 86 if (lower_dentry->d_inode) { 87 fput(inode_info->lower_file); 88 inode_info->lower_file = NULL; 89 } 90 } 91 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 92 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 93} 94 95/** 96 * ecryptfs_init_inode 97 * @inode: The ecryptfs inode 98 * 99 * Set up the ecryptfs inode. 100 */ 101void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 102{ 103 ecryptfs_set_inode_lower(inode, lower_inode); 104 inode->i_ino = lower_inode->i_ino; 105 inode->i_version++; 106 inode->i_op = &ecryptfs_main_iops; 107 inode->i_fop = &ecryptfs_main_fops; 108 inode->i_mapping->a_ops = &ecryptfs_aops; 109} 110 111/** 112 * ecryptfs_statfs 113 * @sb: The ecryptfs super block 114 * @buf: The struct kstatfs to fill in with stats 115 * 116 * Get the filesystem statistics. Currently, we let this pass right through 117 * to the lower filesystem and take no action ourselves. 118 */ 119static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 120{ 121 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 122 123 if (!lower_dentry->d_sb->s_op->statfs) 124 return -ENOSYS; 125 return lower_dentry->d_sb->s_op->statfs(lower_dentry, buf); 126} 127 128/** 129 * ecryptfs_evict_inode 130 * @inode - The ecryptfs inode 131 * 132 * Called by iput() when the inode reference count reached zero 133 * and the inode is not hashed anywhere. Used to clear anything 134 * that needs to be, before the inode is completely destroyed and put 135 * on the inode free list. We use this to drop out reference to the 136 * lower inode. 137 */ 138static void ecryptfs_evict_inode(struct inode *inode) 139{ 140 truncate_inode_pages(&inode->i_data, 0); 141 end_writeback(inode); 142 iput(ecryptfs_inode_to_lower(inode)); 143} 144 145/** 146 * ecryptfs_show_options 147 * 148 * Prints the mount options for a given superblock. 149 * Returns zero; does not fail. 150 */ 151static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 152{ 153 struct super_block *sb = mnt->mnt_sb; 154 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = 155 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat; 156 struct ecryptfs_global_auth_tok *walker; 157 158 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex); 159 list_for_each_entry(walker, 160 &mount_crypt_stat->global_auth_tok_list, 161 mount_crypt_stat_list) { 162 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK) 163 seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig); 164 else 165 seq_printf(m, ",ecryptfs_sig=%s", walker->sig); 166 } 167 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex); 168 169 seq_printf(m, ",ecryptfs_cipher=%s", 170 mount_crypt_stat->global_default_cipher_name); 171 172 if (mount_crypt_stat->global_default_cipher_key_size) 173 seq_printf(m, ",ecryptfs_key_bytes=%zd", 174 mount_crypt_stat->global_default_cipher_key_size); 175 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) 176 seq_printf(m, ",ecryptfs_passthrough"); 177 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) 178 seq_printf(m, ",ecryptfs_xattr_metadata"); 179 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 180 seq_printf(m, ",ecryptfs_encrypted_view"); 181 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS) 182 seq_printf(m, ",ecryptfs_unlink_sigs"); 183 184 return 0; 185} 186 187const struct super_operations ecryptfs_sops = { 188 .alloc_inode = ecryptfs_alloc_inode, 189 .destroy_inode = ecryptfs_destroy_inode, 190 .drop_inode = generic_delete_inode, 191 .statfs = ecryptfs_statfs, 192 .remount_fs = NULL, 193 .evict_inode = ecryptfs_evict_inode, 194 .show_options = ecryptfs_show_options 195}; 196