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/seq_file.h> 30 #include <linux/file.h> 31 #include <linux/crypto.h> 32 #include "ecryptfs_kernel.h" 33 34 struct kmem_cache *ecryptfs_inode_info_cache; 35 36 /** 37 * ecryptfs_alloc_inode - allocate an ecryptfs inode 38 * @sb: Pointer to the ecryptfs super block 39 * 40 * Called to bring an inode into existence. 41 * 42 * Only handle allocation, setting up structures should be done in 43 * ecryptfs_read_inode. This is because the kernel, between now and 44 * then, will 0 out the private data pointer. 45 * 46 * Returns a pointer to a newly allocated inode, NULL otherwise 47 */ 48 static struct inode *ecryptfs_alloc_inode(struct super_block *sb) 49 { 50 struct ecryptfs_inode_info *inode_info; 51 struct inode *inode = NULL; 52 53 inode_info = kmem_cache_alloc(ecryptfs_inode_info_cache, GFP_KERNEL); 54 if (unlikely(!inode_info)) 55 goto out; 56 ecryptfs_init_crypt_stat(&inode_info->crypt_stat); 57 mutex_init(&inode_info->lower_file_mutex); 58 inode_info->lower_file = NULL; 59 inode = &inode_info->vfs_inode; 60 out: 61 return inode; 62 } 63 64 /** 65 * ecryptfs_destroy_inode 66 * @inode: The ecryptfs inode 67 * 68 * This is used during the final destruction of the inode. All 69 * allocation of memory related to the inode, including allocated 70 * memory in the crypt_stat struct, will be released here. This 71 * function also fput()'s the persistent file for the lower inode. 72 * There should be no chance that this deallocation will be missed. 73 */ 74 static void ecryptfs_destroy_inode(struct inode *inode) 75 { 76 struct ecryptfs_inode_info *inode_info; 77 78 inode_info = ecryptfs_inode_to_private(inode); 79 mutex_lock(&inode_info->lower_file_mutex); 80 if (inode_info->lower_file) { 81 struct dentry *lower_dentry = 82 inode_info->lower_file->f_dentry; 83 84 BUG_ON(!lower_dentry); 85 if (lower_dentry->d_inode) { 86 fput(inode_info->lower_file); 87 inode_info->lower_file = NULL; 88 d_drop(lower_dentry); 89 d_delete(lower_dentry); 90 } 91 } 92 mutex_unlock(&inode_info->lower_file_mutex); 93 ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat); 94 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 95 } 96 97 /** 98 * ecryptfs_init_inode 99 * @inode: The ecryptfs inode 100 * 101 * Set up the ecryptfs inode. 102 */ 103 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 104 { 105 ecryptfs_set_inode_lower(inode, lower_inode); 106 inode->i_ino = lower_inode->i_ino; 107 inode->i_version++; 108 inode->i_op = &ecryptfs_main_iops; 109 inode->i_fop = &ecryptfs_main_fops; 110 inode->i_mapping->a_ops = &ecryptfs_aops; 111 } 112 113 /** 114 * ecryptfs_put_super 115 * @sb: Pointer to the ecryptfs super block 116 * 117 * Final actions when unmounting a file system. 118 * This will handle deallocation and release of our private data. 119 */ 120 static void ecryptfs_put_super(struct super_block *sb) 121 { 122 struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb); 123 124 ecryptfs_destroy_mount_crypt_stat(&sb_info->mount_crypt_stat); 125 kmem_cache_free(ecryptfs_sb_info_cache, sb_info); 126 ecryptfs_set_superblock_private(sb, NULL); 127 } 128 129 /** 130 * ecryptfs_statfs 131 * @sb: The ecryptfs super block 132 * @buf: The struct kstatfs to fill in with stats 133 * 134 * Get the filesystem statistics. Currently, we let this pass right through 135 * to the lower filesystem and take no action ourselves. 136 */ 137 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 138 { 139 return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf); 140 } 141 142 /** 143 * ecryptfs_clear_inode 144 * @inode - The ecryptfs inode 145 * 146 * Called by iput() when the inode reference count reached zero 147 * and the inode is not hashed anywhere. Used to clear anything 148 * that needs to be, before the inode is completely destroyed and put 149 * on the inode free list. We use this to drop out reference to the 150 * lower inode. 151 */ 152 static void ecryptfs_clear_inode(struct inode *inode) 153 { 154 iput(ecryptfs_inode_to_lower(inode)); 155 } 156 157 /** 158 * ecryptfs_show_options 159 * 160 * Prints the directory we are currently mounted over. 161 * Returns zero on success; non-zero otherwise 162 */ 163 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 164 { 165 struct super_block *sb = mnt->mnt_sb; 166 struct dentry *lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root); 167 struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(sb->s_root); 168 char *tmp_page; 169 char *path; 170 int rc = 0; 171 172 tmp_page = (char *)__get_free_page(GFP_KERNEL); 173 if (!tmp_page) { 174 rc = -ENOMEM; 175 goto out; 176 } 177 path = d_path(lower_root_dentry, lower_mnt, tmp_page, PAGE_SIZE); 178 if (IS_ERR(path)) { 179 rc = PTR_ERR(path); 180 goto out; 181 } 182 seq_printf(m, ",dir=%s", path); 183 free_page((unsigned long)tmp_page); 184 out: 185 return rc; 186 } 187 188 const struct super_operations ecryptfs_sops = { 189 .alloc_inode = ecryptfs_alloc_inode, 190 .destroy_inode = ecryptfs_destroy_inode, 191 .drop_inode = generic_delete_inode, 192 .put_super = ecryptfs_put_super, 193 .statfs = ecryptfs_statfs, 194 .remount_fs = NULL, 195 .clear_inode = ecryptfs_clear_inode, 196 .show_options = ecryptfs_show_options 197 }; 198