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
33struct 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 */
47static 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;
58out:
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 */
71static 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 */
86void 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 */
103static 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 */
120static 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 */
135static 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 */
146static 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);
167out:
168	return rc;
169}
170
171const 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