1 /* Copyright (c) 2013 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 * Functions for updating the TPM state with the status of boot path.
6 */
7
8 #include "sysincludes.h"
9
10 #include "tlcl.h"
11 #include "tpm_bootmode.h"
12 #include "utility.h"
13 #include "vboot_api.h"
14
15 /* TPM PCRs to use for storing boot mode measurements. */
16 #define BOOT_MODE_PCR 0
17 #define HWID_DIGEST_PCR 1
18
19 /*
20 * Input digests for PCR extend.
21 * These are calculated as:
22 * SHA1("|Developer_Mode||Recovery_Mode||Keyblock_Mode|").
23 * Developer_Mode can be 0 or 1.
24 * Recovery_Mode can be 0 or 1.
25 * Keyblock flags are defined in vboot_struct.h
26 *
27 * We map them to Keyblock_Mode as follows:
28 * -----------------------------------------
29 * Keyblock Flags | Keyblock Mode
30 * -----------------------------------------
31 * 6 (Dev-signed firmware) | 2
32 * 7 Normal-signed firmware | 1
33 * (anything else) | 0
34 */
35
36 const char* kBootStateSHA1Digests[] = {
37 /* SHA1("\x00\x00\x00") */
38 "\x29\xe2\xdc\xfb\xb1\x6f\x63\xbb\x02\x54\xdf\x75\x85\xa1\x5b\xb6"
39 "\xfb\x5e\x92\x7d",
40
41 /* SHA1("\x00\x00\x01") */
42 "\x25\x47\xcc\x73\x6e\x95\x1f\xa4\x91\x98\x53\xc4\x3a\xe8\x90\x86"
43 "\x1a\x3b\x32\x64",
44
45 /* SHA1("\x00\x00\x02") */
46 "\x1e\xf6\x24\x48\x2d\x62\x0e\x43\xe6\xd3\x4d\xa1\xaf\xe4\x62\x67"
47 "\xfc\x69\x5d\x9b",
48
49 /* SHA1("\x00\x01\x00") */
50 "\x62\x57\x18\x91\x21\x5b\x4e\xfc\x1c\xea\xb7\x44\xce\x59\xdd\x0b"
51 "\x66\xea\x6f\x73",
52
53 /* SHA1("\x00\x01\x01") */
54 "\xee\xe4\x47\xed\xc7\x9f\xea\x1c\xa7\xc7\xd3\x4e\x46\x32\x61\xcd"
55 "\xa4\xba\x33\x9e",
56
57 /* SHA1("\x00\x01\x02") */
58 "\x0c\x7a\x62\x3f\xd2\xbb\xc0\x5b\x06\x42\x3b\xe3\x59\xe4\x02\x1d"
59 "\x36\xe7\x21\xad",
60
61 /* SHA1("\x01\x00\x00") */
62 "\x95\x08\xe9\x05\x48\xb0\x44\x0a\x4a\x61\xe5\x74\x3b\x76\xc1\xe3"
63 "\x09\xb2\x3b\x7f",
64
65 /* SHA1("\x01\x00\x01") */
66 "\xc4\x2a\xc1\xc4\x6f\x1d\x4e\x21\x1c\x73\x5c\xc7\xdf\xad\x4f\xf8"
67 "\x39\x11\x10\xe9",
68
69 /* SHA1("\x01\x00\x02") */
70 "\xfa\x01\x0d\x26\x64\xcc\x5b\x3b\x82\xee\x48\x8f\xe2\xb9\xf5\x0f"
71 "\x49\x32\xeb\x8f",
72
73 /* SHA1("\x01\x01\x00") */
74 "\x47\xec\x8d\x98\x36\x64\x33\xdc\x00\x2e\x77\x21\xc9\xe3\x7d\x50"
75 "\x67\x54\x79\x37",
76
77 /* SHA1("\x01\x01\x01") */
78 "\x28\xd8\x6c\x56\xb3\xbf\x26\xd2\x36\x56\x9b\x8d\xc8\xc3\xf9\x1f"
79 "\x32\xf4\x7b\xc7",
80
81 /* SHA1("\x01\x01\x02") */
82 "\x12\xa3\x40\xd7\x89\x7f\xe7\x13\xfc\x8f\x02\xac\x53\x65\xb8\x6e"
83 "\xbf\x35\x31\x78",
84 };
85
86 #define MAX_BOOT_STATE_INDEX (sizeof(kBootStateSHA1Digests)/sizeof(char *))
87
88 /*
89 * Used for PCR extend when the passed-in boot state is invalid or if there is
90 * an internal error.
91 */
92 const uint8_t kBootInvalidSHA1Digest[] = {
93 "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
94 "\xff\xff\xff\xff"
95 };
96
97 /**
98 * Given the boot state, return the correct SHA1 digest index for TPMExtend
99 * in kBootStateSHA1Digests[].
100 */
GetBootStateIndex(int dev_mode,int rec_mode,uint64_t keyblock_flags)101 static int GetBootStateIndex(int dev_mode, int rec_mode,
102 uint64_t keyblock_flags)
103 {
104 int index = 0;
105
106 /*
107 * Convert keyblock flags into keyblock mode which we use to index into
108 * kBootStateSHA1Digest[].
109 */
110 switch(keyblock_flags) {
111 case 6:
112 /*
113 * KEY_BLOCK_FLAG_RECOVERY_0 | KEY_BLOCK_FLAG_DEVELOPER_1
114 *
115 * Developer firmware. */
116 index = 2;
117 break;
118 case 7:
119 /*
120 * KEY_BLOCK_FLAG_RECOVERY_0 | KEY_BLOCK_FLAG_DEVELOPER_0
121 * | KEY_BLOCK_FLAGS_DEVELOPER_1
122 */
123 index = 1;
124 break;
125 default:
126 /* Any other keyblock flags. */
127 index = 0;
128 };
129
130 if (rec_mode)
131 index += 3;
132 if (dev_mode)
133 index += 6;
134 return index;
135 }
136
SetTPMBootModeState(int developer_mode,int recovery_mode,uint64_t fw_keyblock_flags,GoogleBinaryBlockHeader * gbb)137 uint32_t SetTPMBootModeState(int developer_mode, int recovery_mode,
138 uint64_t fw_keyblock_flags,
139 GoogleBinaryBlockHeader *gbb)
140 {
141 uint32_t result0, result1 = 0;
142 const uint8_t *in_digest = NULL;
143 uint8_t out_digest[20]; /* For PCR extend output. */
144 int digest_index = GetBootStateIndex(developer_mode, recovery_mode,
145 fw_keyblock_flags);
146
147 if (digest_index >= 0 && digest_index < MAX_BOOT_STATE_INDEX) {
148 in_digest = (const uint8_t*)
149 kBootStateSHA1Digests[digest_index];
150 } else {
151 /* Internal out of bounds error. */
152 in_digest = kBootInvalidSHA1Digest;
153 }
154
155 result0 = TlclExtend(BOOT_MODE_PCR, in_digest, out_digest);
156 VBDEBUG(("TPM: SetTPMBootModeState boot mode PCR%d result %d\n",
157 BOOT_MODE_PCR, result0));
158
159 /* Extend the HWID Digest into PCR1 (GBB v1.2 and later only) */
160 if (gbb && gbb->minor_version >= 2) {
161 result1 = TlclExtend(HWID_DIGEST_PCR, gbb->hwid_digest,
162 out_digest);
163 VBDEBUG(("TPM: SetTPMBootModeState HWID PCR%d result %d\n",
164 HWID_DIGEST_PCR, result1));
165 }
166
167 /* The caller only looks for nonzero results, not error codes. */
168 return result0 || result1;
169 }
170