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
22 struct 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 */
36 static 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;
52 out:
53 return inode;
54 }
55
56 static 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 */
73 static 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 */
90 static 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 */
119 static 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 */
132 static 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
170 const 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
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