summaryrefslogtreecommitdiff
path: root/firmware/lib21/api.c
blob: 7c1aa0149583f26651b59479e47465f747a761a3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Externally-callable APIs
 * (Firmware portion)
 */

#include "2sysincludes.h"
#include "2api.h"
#include "2common.h"
#include "2misc.h"
#include "2nvstorage.h"
#include "2secdata.h"
#include "2sha.h"
#include "2rsa.h"
#include "vb2_common.h"

int vb2api_fw_phase3(struct vb2_context *ctx)
{
	int rv;

	/* Verify firmware keyblock */
	rv = vb2_load_fw_keyblock(ctx);
	if (rv) {
		vb2_fail(ctx, VB2_RECOVERY_RO_INVALID_RW, rv);
		return rv;
	}

	/* Verify firmware preamble */
	rv = vb2_load_fw_preamble(ctx);
	if (rv) {
		vb2_fail(ctx, VB2_RECOVERY_RO_INVALID_RW, rv);
		return rv;
	}

	return VB2_SUCCESS;
}

int vb2api_init_hash2(struct vb2_context *ctx,
		      const struct vb2_guid *guid,
		      uint32_t *size)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	const struct vb2_fw_preamble *pre;
	const struct vb2_signature *sig = NULL;
	struct vb2_digest_context *dc;
	struct vb2_workbuf wb;
	uint32_t hash_offset;
	int i, rv;

	vb2_workbuf_from_ctx(ctx, &wb);

	/* Get preamble pointer */
	if (!sd->workbuf_preamble_size)
		return VB2_ERROR_API_INIT_HASH_PREAMBLE;
	pre = (const struct vb2_fw_preamble *)
		(ctx->workbuf + sd->workbuf_preamble_offset);

	/* Find the matching signature */
	hash_offset = pre->hash_offset;
	for (i = 0; i < pre->hash_count; i++) {
		sig = (const struct vb2_signature *)
			((uint8_t *)pre + hash_offset);

		if (!memcmp(guid, &sig->guid, sizeof(*guid)))
			break;

		hash_offset += sig->c.total_size;
	}
	if (i >= pre->hash_count)
		return VB2_ERROR_API_INIT_HASH_GUID;  /* No match */

	/* Allocate workbuf space for the hash */
	if (sd->workbuf_hash_size) {
		dc = (struct vb2_digest_context *)
			(ctx->workbuf + sd->workbuf_hash_offset);
	} else {
		uint32_t dig_size = sizeof(*dc);

		dc = vb2_workbuf_alloc(&wb, dig_size);
		if (!dc)
			return VB2_ERROR_API_INIT_HASH_WORKBUF;

		sd->workbuf_hash_offset = vb2_offset_of(ctx->workbuf, dc);
		sd->workbuf_hash_size = dig_size;
		ctx->workbuf_used = sd->workbuf_hash_offset + dig_size;
	}

	sd->hash_tag = vb2_offset_of(ctx->workbuf, sig);
	sd->hash_remaining_size = sig->data_size;

	if (size)
		*size = sig->data_size;

	if (!(pre->flags & VB2_FIRMWARE_PREAMBLE_DISALLOW_HWCRYPTO)) {
		rv = vb2ex_hwcrypto_digest_init(sig->hash_alg, sig->data_size);
		if (!rv) {
			VB2_DEBUG("Using HW crypto engine for hash_alg %d\n",
				  sig->hash_alg);
			dc->hash_alg = sig->hash_alg;
			dc->using_hwcrypto = 1;
			return VB2_SUCCESS;
		}
		if (rv != VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED)
			return rv;
		VB2_DEBUG("HW crypto for hash_alg %d not supported, using SW\n",
			  sig->hash_alg);
	} else {
		VB2_DEBUG("HW crypto forbidden by preamble, using SW\n");
	}

	return vb2_digest_init(dc, sig->hash_alg);
}

int vb2api_check_hash(struct vb2_context *ctx)
{
	struct vb2_shared_data *sd = vb2_get_sd(ctx);
	struct vb2_digest_context *dc = (struct vb2_digest_context *)
		(ctx->workbuf + sd->workbuf_hash_offset);
	struct vb2_workbuf wb;

	uint8_t *digest;
	uint32_t digest_size = vb2_digest_size(dc->hash_alg);

	const struct vb2_signature *sig;

	int rv;

	vb2_workbuf_from_ctx(ctx, &wb);

	/* Get signature pointer */
	if (!sd->hash_tag)
		return VB2_ERROR_API_CHECK_HASH_TAG;
	sig = (const struct vb2_signature *)(ctx->workbuf + sd->hash_tag);

	/* Must have initialized hash digest work area */
	if (!sd->workbuf_hash_size)
		return VB2_ERROR_API_CHECK_HASH_WORKBUF;

	/* Should have hashed the right amount of data */
	if (sd->hash_remaining_size)
		return VB2_ERROR_API_CHECK_HASH_SIZE;

	/* Allocate the digest */
	digest = vb2_workbuf_alloc(&wb, digest_size);
	if (!digest)
		return VB2_ERROR_API_CHECK_HASH_WORKBUF_DIGEST;

	/* Finalize the digest */
	if (dc->using_hwcrypto)
		rv = vb2ex_hwcrypto_digest_finalize(digest, digest_size);
	else
		rv = vb2_digest_finalize(dc, digest, digest_size);
	if (rv)
		return rv;

	/* Compare with the signature */
	if (vb2_safe_memcmp(digest, (const uint8_t *)sig + sig->sig_offset,
			    digest_size))
		return VB2_ERROR_API_CHECK_HASH_SIG;

	// TODO: the old check-hash function called vb2_fail() on any mismatch.
	// I don't think it should do that; the caller should.

	return VB2_SUCCESS;
}