xref: /linux/fs/ecryptfs/super.c (revision 4f2c0a4acffbec01079c28f839422e64ddeff004)
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  */
ecryptfs_alloc_inode(struct super_block * sb)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 
ecryptfs_free_inode(struct inode * inode)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  */
ecryptfs_destroy_inode(struct inode * inode)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  */
ecryptfs_statfs(struct dentry * dentry,struct kstatfs * buf)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  */
ecryptfs_evict_inode(struct inode * inode)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  */
ecryptfs_show_options(struct seq_file * m,struct dentry * root)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