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
vb2_unpack_key_data(struct vb2_public_key * key,const uint8_t * key_data,uint32_t key_size)13 int 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
vb2_unpack_key(struct vb2_public_key * key,const uint8_t * buf,uint32_t size)45 int 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