1/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
2 * Use of this source code is governed by a BSD-style license that can be
3 * found in the LICENSE file.
4 *
5 * Key unpacking functions
6 */
7
8#include "2sysincludes.h"
9#include "2common.h"
10#include "2rsa.h"
11#include "vb2_common.h"
12
13int vb2_unpack_key_data(struct vb2_public_key *key,
14			 const uint8_t *key_data,
15			 uint32_t key_size)
16{
17	const uint32_t *buf32 = (const uint32_t *)key_data;
18	uint32_t expected_key_size = vb2_packed_key_size(key->sig_alg);
19
20	/* Make sure buffer is the correct length */
21	if (!expected_key_size || expected_key_size != key_size) {
22		VB2_DEBUG("Wrong key size for algorithm\n");
23		return VB2_ERROR_UNPACK_KEY_SIZE;
24	}
25
26	/* Check for alignment */
27	if (!vb2_aligned(buf32, sizeof(uint32_t)))
28		return VB2_ERROR_UNPACK_KEY_ALIGN;
29
30	key->arrsize = buf32[0];
31
32	/* Sanity check key array size */
33	if (key->arrsize * sizeof(uint32_t) != vb2_rsa_sig_size(key->sig_alg))
34		return VB2_ERROR_UNPACK_KEY_ARRAY_SIZE;
35
36	key->n0inv = buf32[1];
37
38	/* Arrays point inside the key data */
39	key->n = buf32 + 2;
40	key->rr = buf32 + 2 + key->arrsize;
41
42	return VB2_SUCCESS;
43}
44
45int vb2_unpack_key(struct vb2_public_key *key,
46		    const uint8_t *buf,
47		    uint32_t size)
48{
49	const struct vb2_packed_key *pkey =
50		(const struct vb2_packed_key *)buf;
51	uint32_t sig_size;
52	uint32_t min_offset = 0;
53	int rv;
54
55	/* Check magic number */
56	if (pkey->c.magic != VB2_MAGIC_PACKED_KEY)
57		return VB2_ERROR_UNPACK_KEY_MAGIC;
58
59	rv = vb2_verify_common_header(buf, size);
60	if (rv)
61		return rv;
62
63	/* Make sure key data is inside */
64	rv = vb2_verify_common_member(pkey, &min_offset,
65				      pkey->key_offset, pkey->key_size);
66	if (rv)
67		return rv;
68
69	/*
70	 * Check for compatible version.  No need to check minor version, since
71	 * that's compatible across readers matching the major version, and we
72	 * haven't added any new fields.
73	 */
74	if (pkey->c.struct_version_major != VB2_PACKED_KEY_VERSION_MAJOR)
75		return VB2_ERROR_UNPACK_KEY_STRUCT_VERSION;
76
77	/* Copy key algorithms */
78	key->hash_alg = pkey->hash_alg;
79	if (!vb2_digest_size(key->hash_alg))
80		return VB2_ERROR_UNPACK_KEY_HASH_ALGORITHM;
81
82	key->sig_alg = pkey->sig_alg;
83	if (key->sig_alg != VB2_SIG_NONE) {
84		sig_size = vb2_rsa_sig_size(key->sig_alg);
85		if (!sig_size)
86			return VB2_ERROR_UNPACK_KEY_SIG_ALGORITHM;
87		rv = vb2_unpack_key_data(
88				key,
89				(const uint8_t *)pkey + pkey->key_offset,
90				pkey->key_size);
91		if (rv)
92			return rv;
93	}
94
95	/* Key description */
96	key->desc = vb2_common_desc(pkey);
97	key->version = pkey->key_version;
98	key->guid = &pkey->guid;
99
100	return VB2_SUCCESS;
101}
102