1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 1997-2003 Erez Zadok
6 * Copyright (C) 2001-2003 Stony Brook University
7 * Copyright (C) 2004-2006 International Business Machines Corp.
8 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
9 *              Michael C. Thompson <mcthomps@us.ibm.com>
10 */
11
12#include <linux/fs.h>
13#include <linux/mount.h>
14#include <linux/key.h>
15#include <linux/slab.h>
16#include <linux/seq_file.h>
17#include <linux/file.h>
18#include <linux/statfs.h>
19#include <linux/magic.h>
20#include "ecryptfs_kernel.h"
21
22struct kmem_cache *ecryptfs_inode_info_cache;
23
24/**
25 * ecryptfs_alloc_inode - allocate an ecryptfs inode
26 * @sb: Pointer to the ecryptfs super block
27 *
28 * Called to bring an inode into existence.
29 *
30 * Only handle allocation, setting up structures should be done in
31 * ecryptfs_read_inode. This is because the kernel, between now and
32 * then, will 0 out the private data pointer.
33 *
34 * Returns a pointer to a newly allocated inode, NULL otherwise
35 */
36static struct inode *ecryptfs_alloc_inode(struct super_block *sb)
37{
38	struct ecryptfs_inode_info *inode_info;
39	struct inode *inode = NULL;
40
41	inode_info = alloc_inode_sb(sb, ecryptfs_inode_info_cache, GFP_KERNEL);
42	if (unlikely(!inode_info))
43		goto out;
44	if (ecryptfs_init_crypt_stat(&inode_info->crypt_stat)) {
45		kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
46		goto out;
47	}
48	mutex_init(&inode_info->lower_file_mutex);
49	atomic_set(&inode_info->lower_file_count, 0);
50	inode_info->lower_file = NULL;
51	inode = &inode_info->vfs_inode;
52out:
53	return inode;
54}
55
56static void ecryptfs_free_inode(struct inode *inode)
57{
58	struct ecryptfs_inode_info *inode_info;
59	inode_info = ecryptfs_inode_to_private(inode);
60
61	kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
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.
71 * There should be no chance that this deallocation will be missed.
72 */
73static void ecryptfs_destroy_inode(struct inode *inode)
74{
75	struct ecryptfs_inode_info *inode_info;
76
77	inode_info = ecryptfs_inode_to_private(inode);
78	BUG_ON(inode_info->lower_file);
79	ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
80}
81
82/**
83 * ecryptfs_statfs
84 * @dentry: The ecryptfs dentry
85 * @buf: The struct kstatfs to fill in with stats
86 *
87 * Get the filesystem statistics. Currently, we let this pass right through
88 * to the lower filesystem and take no action ourselves.
89 */
90static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
91{
92	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
93	int rc;
94
95	if (!lower_dentry->d_sb->s_op->statfs)
96		return -ENOSYS;
97
98	rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
99	if (rc)
100		return rc;
101
102	buf->f_type = ECRYPTFS_SUPER_MAGIC;
103	rc = ecryptfs_set_f_namelen(&buf->f_namelen, buf->f_namelen,
104	       &ecryptfs_superblock_to_private(dentry->d_sb)->mount_crypt_stat);
105
106	return rc;
107}
108
109/**
110 * ecryptfs_evict_inode
111 * @inode: The ecryptfs inode
112 *
113 * Called by iput() when the inode reference count reached zero
114 * and the inode is not hashed anywhere.  Used to clear anything
115 * that needs to be, before the inode is completely destroyed and put
116 * on the inode free list. We use this to drop out reference to the
117 * lower inode.
118 */
119static void ecryptfs_evict_inode(struct inode *inode)
120{
121	truncate_inode_pages_final(&inode->i_data);
122	clear_inode(inode);
123	iput(ecryptfs_inode_to_lower(inode));
124}
125
126/*
127 * ecryptfs_show_options
128 *
129 * Prints the mount options for a given superblock.
130 * Returns zero; does not fail.
131 */
132static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
133{
134	struct super_block *sb = root->d_sb;
135	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
136		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
137	struct ecryptfs_global_auth_tok *walker;
138
139	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
140	list_for_each_entry(walker,
141			    &mount_crypt_stat->global_auth_tok_list,
142			    mount_crypt_stat_list) {
143		if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
144			seq_printf(m, ",ecryptfs_fnek_sig=%s", walker->sig);
145		else
146			seq_printf(m, ",ecryptfs_sig=%s", walker->sig);
147	}
148	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
149
150	seq_printf(m, ",ecryptfs_cipher=%s",
151		mount_crypt_stat->global_default_cipher_name);
152
153	if (mount_crypt_stat->global_default_cipher_key_size)
154		seq_printf(m, ",ecryptfs_key_bytes=%zd",
155			   mount_crypt_stat->global_default_cipher_key_size);
156	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
157		seq_printf(m, ",ecryptfs_passthrough");
158	if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
159		seq_printf(m, ",ecryptfs_xattr_metadata");
160	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
161		seq_printf(m, ",ecryptfs_encrypted_view");
162	if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
163		seq_printf(m, ",ecryptfs_unlink_sigs");
164	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
165		seq_printf(m, ",ecryptfs_mount_auth_tok_only");
166
167	return 0;
168}
169
170const struct super_operations ecryptfs_sops = {
171	.alloc_inode = ecryptfs_alloc_inode,
172	.destroy_inode = ecryptfs_destroy_inode,
173	.free_inode = ecryptfs_free_inode,
174	.statfs = ecryptfs_statfs,
175	.remount_fs = NULL,
176	.evict_inode = ecryptfs_evict_inode,
177	.show_options = ecryptfs_show_options
178};
179