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/crypto.h> 31 #include "ecryptfs_kernel.h" 32 33 struct kmem_cache *ecryptfs_inode_info_cache; 34 35 /** 36 * ecryptfs_alloc_inode - allocate an ecryptfs inode 37 * @sb: Pointer to the ecryptfs super block 38 * 39 * Called to bring an inode into existence. 40 * 41 * Only handle allocation, setting up structures should be done in 42 * ecryptfs_read_inode. This is because the kernel, between now and 43 * then, will 0 out the private data pointer. 44 * 45 * Returns a pointer to a newly allocated inode, NULL otherwise 46 */ 47 static struct inode *ecryptfs_alloc_inode(struct super_block *sb) 48 { 49 struct ecryptfs_inode_info *ecryptfs_inode; 50 struct inode *inode = NULL; 51 52 ecryptfs_inode = kmem_cache_alloc(ecryptfs_inode_info_cache, 53 GFP_KERNEL); 54 if (unlikely(!ecryptfs_inode)) 55 goto out; 56 ecryptfs_init_crypt_stat(&ecryptfs_inode->crypt_stat); 57 inode = &ecryptfs_inode->vfs_inode; 58 out: 59 return inode; 60 } 61 62 /** 63 * ecryptfs_destroy_inode 64 * @inode: The ecryptfs inode 65 * 66 * This is used during the final destruction of the inode. 67 * All allocation of memory related to the inode, including allocated 68 * memory in the crypt_stat struct, will be released here. 69 * There should be no chance that this deallocation will be missed. 70 */ 71 static void ecryptfs_destroy_inode(struct inode *inode) 72 { 73 struct ecryptfs_inode_info *inode_info; 74 75 inode_info = ecryptfs_inode_to_private(inode); 76 ecryptfs_destruct_crypt_stat(&inode_info->crypt_stat); 77 kmem_cache_free(ecryptfs_inode_info_cache, inode_info); 78 } 79 80 /** 81 * ecryptfs_init_inode 82 * @inode: The ecryptfs inode 83 * 84 * Set up the ecryptfs inode. 85 */ 86 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode) 87 { 88 ecryptfs_set_inode_lower(inode, lower_inode); 89 inode->i_ino = lower_inode->i_ino; 90 inode->i_version++; 91 inode->i_op = &ecryptfs_main_iops; 92 inode->i_fop = &ecryptfs_main_fops; 93 inode->i_mapping->a_ops = &ecryptfs_aops; 94 } 95 96 /** 97 * ecryptfs_put_super 98 * @sb: Pointer to the ecryptfs super block 99 * 100 * Final actions when unmounting a file system. 101 * This will handle deallocation and release of our private data. 102 */ 103 static void ecryptfs_put_super(struct super_block *sb) 104 { 105 struct ecryptfs_sb_info *sb_info = ecryptfs_superblock_to_private(sb); 106 107 ecryptfs_destruct_mount_crypt_stat(&sb_info->mount_crypt_stat); 108 kmem_cache_free(ecryptfs_sb_info_cache, sb_info); 109 ecryptfs_set_superblock_private(sb, NULL); 110 } 111 112 /** 113 * ecryptfs_statfs 114 * @sb: The ecryptfs super block 115 * @buf: The struct kstatfs to fill in with stats 116 * 117 * Get the filesystem statistics. Currently, we let this pass right through 118 * to the lower filesystem and take no action ourselves. 119 */ 120 static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf) 121 { 122 return vfs_statfs(ecryptfs_dentry_to_lower(dentry), buf); 123 } 124 125 /** 126 * ecryptfs_clear_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_clear_inode(struct inode *inode) 136 { 137 iput(ecryptfs_inode_to_lower(inode)); 138 } 139 140 /** 141 * ecryptfs_show_options 142 * 143 * Prints the directory we are currently mounted over. 144 * Returns zero on success; non-zero otherwise 145 */ 146 static int ecryptfs_show_options(struct seq_file *m, struct vfsmount *mnt) 147 { 148 struct super_block *sb = mnt->mnt_sb; 149 struct dentry *lower_root_dentry = ecryptfs_dentry_to_lower(sb->s_root); 150 struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(sb->s_root); 151 char *tmp_page; 152 char *path; 153 int rc = 0; 154 155 tmp_page = (char *)__get_free_page(GFP_KERNEL); 156 if (!tmp_page) { 157 rc = -ENOMEM; 158 goto out; 159 } 160 path = d_path(lower_root_dentry, lower_mnt, tmp_page, PAGE_SIZE); 161 if (IS_ERR(path)) { 162 rc = PTR_ERR(path); 163 goto out; 164 } 165 seq_printf(m, ",dir=%s", path); 166 free_page((unsigned long)tmp_page); 167 out: 168 return rc; 169 } 170 171 const struct super_operations ecryptfs_sops = { 172 .alloc_inode = ecryptfs_alloc_inode, 173 .destroy_inode = ecryptfs_destroy_inode, 174 .drop_inode = generic_delete_inode, 175 .put_super = ecryptfs_put_super, 176 .statfs = ecryptfs_statfs, 177 .remount_fs = NULL, 178 .clear_inode = ecryptfs_clear_inode, 179 .show_options = ecryptfs_show_options 180 }; 181