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