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 ecryptfs_init_crypt_stat(crypt_stat: &inode_info->crypt_stat);
45 mutex_init(&inode_info->lower_file_mutex);
46 atomic_set(v: &inode_info->lower_file_count, i: 0);
47 inode_info->lower_file = NULL;
48 inode = &inode_info->vfs_inode;
49out:
50 return inode;
51}
52
53static void ecryptfs_free_inode(struct inode *inode)
54{
55 struct ecryptfs_inode_info *inode_info;
56 inode_info = ecryptfs_inode_to_private(inode);
57
58 kmem_cache_free(s: ecryptfs_inode_info_cache, objp: inode_info);
59}
60
61/**
62 * ecryptfs_destroy_inode
63 * @inode: The ecryptfs inode
64 *
65 * This is used during the final destruction of the inode. All
66 * allocation of memory related to the inode, including allocated
67 * memory in the crypt_stat struct, will be released here.
68 * There should be no chance that this deallocation will be missed.
69 */
70static void ecryptfs_destroy_inode(struct inode *inode)
71{
72 struct ecryptfs_inode_info *inode_info;
73
74 inode_info = ecryptfs_inode_to_private(inode);
75 BUG_ON(inode_info->lower_file);
76 ecryptfs_destroy_crypt_stat(crypt_stat: &inode_info->crypt_stat);
77}
78
79/**
80 * ecryptfs_statfs
81 * @dentry: The ecryptfs dentry
82 * @buf: The struct kstatfs to fill in with stats
83 *
84 * Get the filesystem statistics. Currently, we let this pass right through
85 * to the lower filesystem and take no action ourselves.
86 */
87static int ecryptfs_statfs(struct dentry *dentry, struct kstatfs *buf)
88{
89 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
90 int rc;
91
92 if (!lower_dentry->d_sb->s_op->statfs)
93 return -ENOSYS;
94
95 rc = lower_dentry->d_sb->s_op->statfs(lower_dentry, buf);
96 if (rc)
97 return rc;
98
99 buf->f_type = ECRYPTFS_SUPER_MAGIC;
100 rc = ecryptfs_set_f_namelen(namelen: &buf->f_namelen, lower_namelen: buf->f_namelen,
101 mount_crypt_stat: &ecryptfs_superblock_to_private(sb: dentry->d_sb)->mount_crypt_stat);
102
103 return rc;
104}
105
106/**
107 * ecryptfs_evict_inode
108 * @inode: The ecryptfs inode
109 *
110 * Called by iput() when the inode reference count reached zero
111 * and the inode is not hashed anywhere. Used to clear anything
112 * that needs to be, before the inode is completely destroyed and put
113 * on the inode free list. We use this to drop out reference to the
114 * lower inode.
115 */
116static void ecryptfs_evict_inode(struct inode *inode)
117{
118 truncate_inode_pages_final(mapping: &inode->i_data);
119 clear_inode(inode);
120 iput(ecryptfs_inode_to_lower(inode));
121}
122
123/*
124 * ecryptfs_show_options
125 *
126 * Prints the mount options for a given superblock.
127 * Returns zero; does not fail.
128 */
129static int ecryptfs_show_options(struct seq_file *m, struct dentry *root)
130{
131 struct super_block *sb = root->d_sb;
132 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
133 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
134 struct ecryptfs_global_auth_tok *walker;
135
136 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
137 list_for_each_entry(walker,
138 &mount_crypt_stat->global_auth_tok_list,
139 mount_crypt_stat_list) {
140 if (walker->flags & ECRYPTFS_AUTH_TOK_FNEK)
141 seq_printf(m, fmt: ",ecryptfs_fnek_sig=%s", walker->sig);
142 else
143 seq_printf(m, fmt: ",ecryptfs_sig=%s", walker->sig);
144 }
145 mutex_unlock(lock: &mount_crypt_stat->global_auth_tok_list_mutex);
146
147 seq_printf(m, fmt: ",ecryptfs_cipher=%s",
148 mount_crypt_stat->global_default_cipher_name);
149
150 if (mount_crypt_stat->global_default_cipher_key_size)
151 seq_printf(m, fmt: ",ecryptfs_key_bytes=%zd",
152 mount_crypt_stat->global_default_cipher_key_size);
153 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)
154 seq_printf(m, fmt: ",ecryptfs_passthrough");
155 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
156 seq_printf(m, fmt: ",ecryptfs_xattr_metadata");
157 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
158 seq_printf(m, fmt: ",ecryptfs_encrypted_view");
159 if (mount_crypt_stat->flags & ECRYPTFS_UNLINK_SIGS)
160 seq_printf(m, fmt: ",ecryptfs_unlink_sigs");
161 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
162 seq_printf(m, fmt: ",ecryptfs_mount_auth_tok_only");
163
164 return 0;
165}
166
167const struct super_operations ecryptfs_sops = {
168 .alloc_inode = ecryptfs_alloc_inode,
169 .destroy_inode = ecryptfs_destroy_inode,
170 .free_inode = ecryptfs_free_inode,
171 .statfs = ecryptfs_statfs,
172 .evict_inode = ecryptfs_evict_inode,
173 .show_options = ecryptfs_show_options
174};
175

source code of linux/fs/ecryptfs/super.c