ecryptfs_format.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * ecryptfs_format.c: helper functions for the encrypted key type
 4 *
 5 * Copyright (C) 2006 International Business Machines Corp.
 6 * Copyright (C) 2010 Politecnico di Torino, Italy
 7 *                    TORSEC group -- https://security.polito.it
 8 *
 9 * Authors:
10 * Michael A. Halcrow <mahalcro@us.ibm.com>
11 * Tyler Hicks <tyhicks@ou.edu>
12 * Roberto Sassu <roberto.sassu@polito.it>
13 */
14
15#include <linux/export.h>
16#include <linux/string.h>
17#include "ecryptfs_format.h"
18
19u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok)
20{
21	return auth_tok->token.password.session_key_encryption_key;
22}
23EXPORT_SYMBOL(ecryptfs_get_auth_tok_key);
24
25/*
26 * ecryptfs_get_versions()
27 *
28 * Source code taken from the software 'ecryptfs-utils' version 83.
29 *
30 */
31void ecryptfs_get_versions(int *major, int *minor, int *file_version)
32{
33	*major = ECRYPTFS_VERSION_MAJOR;
34	*minor = ECRYPTFS_VERSION_MINOR;
35	if (file_version)
36		*file_version = ECRYPTFS_SUPPORTED_FILE_VERSION;
37}
38EXPORT_SYMBOL(ecryptfs_get_versions);
39
40/*
41 * ecryptfs_fill_auth_tok - fill the ecryptfs_auth_tok structure
42 *
43 * Fill the ecryptfs_auth_tok structure with required ecryptfs data.
44 * The source code is inspired to the original function generate_payload()
45 * shipped with the software 'ecryptfs-utils' version 83.
46 *
47 */
48int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok,
49			   const char *key_desc)
50{
51	int major, minor;
52
53	ecryptfs_get_versions(&major, &minor, NULL);
54	auth_tok->version = (((uint16_t)(major << 8) & 0xFF00)
55			     | ((uint16_t)minor & 0x00FF));
56	auth_tok->token_type = ECRYPTFS_PASSWORD;
57	strscpy_pad(auth_tok->token.password.signature, key_desc);
58	auth_tok->token.password.session_key_encryption_key_bytes =
59		ECRYPTFS_MAX_KEY_BYTES;
60	/*
61	 * Removed auth_tok->token.password.salt and
62	 * auth_tok->token.password.session_key_encryption_key
63	 * initialization from the original code
64	 */
65	/* TODO: Make the hash parameterizable via policy */
66	auth_tok->token.password.flags |=
67		ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET;
68	/* The kernel code will encrypt the session key. */
69	auth_tok->session_key.encrypted_key[0] = 0;
70	auth_tok->session_key.encrypted_key_size = 0;
71	/* Default; subject to change by kernel eCryptfs */
72	auth_tok->token.password.hash_algo = PGP_DIGEST_ALGO_SHA512;
73	auth_tok->token.password.flags &= ~(ECRYPTFS_PERSISTENT_PASSWORD);
74	return 0;
75}
76EXPORT_SYMBOL(ecryptfs_fill_auth_tok);