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f4f395e1ca
GBB header v1.2 adds a digest of the HWID string to the blob (and
maintains it when updated with the current futility/gbb_utility).
This CL causes VbSelectFirmware() to extend PCR1 with that HWID
digest (only for GBB header v1.2 and later, of course).
Tests are updated.
This also adds a "pcr" command to futility to help determine that
the change is working on the hardware (adds 4K bytes or fewer to
the size of the executable).
BUG=chromium:415714
BRANCH=ToT (and maybe others?)
TEST=make runtests, manual install on HW
To test on hardware, build and update a system with this change
(both the disk image and the RO firmware).
NOTE: The BIOS image must be built in a chroot that is using the
current version of futility. You may need to update your chroot
if your BIOS image still produces v1.1 GBB headers. Check with:
futility show <firmware_image.bin> | grep -B1 'digest:'
Boot the new system with a new test image, then follow these steps:
Read the BIOS:
# flashrom -r /tmp/bios.bin
Make sure the GBB has a valid digest for the HWID.
# futility show /tmp/bios.bin | grep -B1 'digest:'
HWID: SAMUS TEST 8028
digest: 4172d24f40bf72cc0ab8... <valid>
#
Extract only the sha1sum-sized part of the HWID digest:
# futility show /tmp/bios.bin | awk '/digest:/ {print $2}' | colrm 41
4172d24f40bf72cc0ab878b4c589b8fe9cf4405e
#
Simulate extending that value in a PCR using the futility "pcr"
command:
# futility pcr 4172d24f40bf72cc0ab878b4c589b8fe9cf4405e
PCR: 0000000000000000000000000000000000000000
+ 4172d24f40bf72cc0ab878b4c589b8fe9cf4405e
PCR: b6e5ffd2d898a7b15236ad22ca25f53ac1f40776
#
Finally, look at the value of PCR1. It should match the last line
of the futility pcr output:
# head /sys/class/misc/tpm0/device/pcrs | grep PCR-01
PCR-01: B6 E5 FF D2 D8 98 A7 B1 52 36 AD 22 CA 25 F5 3A C1 F4 07 76
#
Change-Id: I09cf855f1a24616cc1a9ddb676670edbc76827d2
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/226408
Reviewed-by: Darren Krahn <dkrahn@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
170 lines
4.6 KiB
C
170 lines
4.6 KiB
C
/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* Functions for updating the TPM state with the status of boot path.
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*/
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#include "sysincludes.h"
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#include "tlcl.h"
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#include "tpm_bootmode.h"
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#include "utility.h"
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#include "vboot_api.h"
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/* TPM PCRs to use for storing boot mode measurements. */
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#define BOOT_MODE_PCR 0
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#define HWID_DIGEST_PCR 1
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/*
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* Input digests for PCR extend.
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* These are calculated as:
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* SHA1("|Developer_Mode||Recovery_Mode||Keyblock_Mode|").
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* Developer_Mode can be 0 or 1.
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* Recovery_Mode can be 0 or 1.
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* Keyblock flags are defined in vboot_struct.h
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*
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* We map them to Keyblock_Mode as follows:
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* -----------------------------------------
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* Keyblock Flags | Keyblock Mode
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* -----------------------------------------
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* 6 (Dev-signed firmware) | 2
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* 7 Normal-signed firmware | 1
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* (anything else) | 0
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*/
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const char* kBootStateSHA1Digests[] = {
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/* SHA1("\x00\x00\x00") */
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"\x29\xe2\xdc\xfb\xb1\x6f\x63\xbb\x02\x54\xdf\x75\x85\xa1\x5b\xb6"
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"\xfb\x5e\x92\x7d",
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/* SHA1("\x00\x00\x01") */
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"\x25\x47\xcc\x73\x6e\x95\x1f\xa4\x91\x98\x53\xc4\x3a\xe8\x90\x86"
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"\x1a\x3b\x32\x64",
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/* SHA1("\x00\x00\x02") */
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"\x1e\xf6\x24\x48\x2d\x62\x0e\x43\xe6\xd3\x4d\xa1\xaf\xe4\x62\x67"
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"\xfc\x69\x5d\x9b",
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/* SHA1("\x00\x01\x00") */
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"\x62\x57\x18\x91\x21\x5b\x4e\xfc\x1c\xea\xb7\x44\xce\x59\xdd\x0b"
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"\x66\xea\x6f\x73",
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/* SHA1("\x00\x01\x01") */
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"\xee\xe4\x47\xed\xc7\x9f\xea\x1c\xa7\xc7\xd3\x4e\x46\x32\x61\xcd"
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"\xa4\xba\x33\x9e",
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/* SHA1("\x00\x01\x02") */
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"\x0c\x7a\x62\x3f\xd2\xbb\xc0\x5b\x06\x42\x3b\xe3\x59\xe4\x02\x1d"
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"\x36\xe7\x21\xad",
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/* SHA1("\x01\x00\x00") */
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"\x95\x08\xe9\x05\x48\xb0\x44\x0a\x4a\x61\xe5\x74\x3b\x76\xc1\xe3"
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"\x09\xb2\x3b\x7f",
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/* SHA1("\x01\x00\x01") */
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"\xc4\x2a\xc1\xc4\x6f\x1d\x4e\x21\x1c\x73\x5c\xc7\xdf\xad\x4f\xf8"
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"\x39\x11\x10\xe9",
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/* SHA1("\x01\x00\x02") */
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"\xfa\x01\x0d\x26\x64\xcc\x5b\x3b\x82\xee\x48\x8f\xe2\xb9\xf5\x0f"
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"\x49\x32\xeb\x8f",
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/* SHA1("\x01\x01\x00") */
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"\x47\xec\x8d\x98\x36\x64\x33\xdc\x00\x2e\x77\x21\xc9\xe3\x7d\x50"
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"\x67\x54\x79\x37",
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/* SHA1("\x01\x01\x01") */
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"\x28\xd8\x6c\x56\xb3\xbf\x26\xd2\x36\x56\x9b\x8d\xc8\xc3\xf9\x1f"
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"\x32\xf4\x7b\xc7",
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/* SHA1("\x01\x01\x02") */
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"\x12\xa3\x40\xd7\x89\x7f\xe7\x13\xfc\x8f\x02\xac\x53\x65\xb8\x6e"
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"\xbf\x35\x31\x78",
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};
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#define MAX_BOOT_STATE_INDEX (sizeof(kBootStateSHA1Digests)/sizeof(char *))
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/*
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* Used for PCR extend when the passed-in boot state is invalid or if there is
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* an internal error.
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*/
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const uint8_t kBootInvalidSHA1Digest[] = {
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"\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
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"\xff\xff\xff\xff"
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};
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/**
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* Given the boot state, return the correct SHA1 digest index for TPMExtend
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* in kBootStateSHA1Digests[].
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*/
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static int GetBootStateIndex(int dev_mode, int rec_mode,
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uint64_t keyblock_flags)
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{
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int index = 0;
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/*
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* Convert keyblock flags into keyblock mode which we use to index into
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* kBootStateSHA1Digest[].
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*/
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switch(keyblock_flags) {
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case 6:
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/*
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* KEY_BLOCK_FLAG_RECOVERY_0 | KEY_BLOCK_FLAG_DEVELOPER_1
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*
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* Developer firmware. */
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index = 2;
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break;
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case 7:
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/*
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* KEY_BLOCK_FLAG_RECOVERY_0 | KEY_BLOCK_FLAG_DEVELOPER_0
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* | KEY_BLOCK_FLAGS_DEVELOPER_1
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*/
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index = 1;
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break;
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default:
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/* Any other keyblock flags. */
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index = 0;
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};
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if (rec_mode)
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index += 3;
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if (dev_mode)
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index += 6;
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return index;
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}
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uint32_t SetTPMBootModeState(int developer_mode, int recovery_mode,
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uint64_t fw_keyblock_flags,
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GoogleBinaryBlockHeader *gbb)
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{
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uint32_t result0, result1 = 0;
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const uint8_t *in_digest = NULL;
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uint8_t out_digest[20]; /* For PCR extend output. */
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int digest_index = GetBootStateIndex(developer_mode, recovery_mode,
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fw_keyblock_flags);
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if (digest_index >= 0 && digest_index < MAX_BOOT_STATE_INDEX) {
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in_digest = (const uint8_t*)
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kBootStateSHA1Digests[digest_index];
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} else {
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/* Internal out of bounds error. */
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in_digest = kBootInvalidSHA1Digest;
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}
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result0 = TlclExtend(BOOT_MODE_PCR, in_digest, out_digest);
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VBDEBUG(("TPM: SetTPMBootModeState boot mode PCR%d result %d\n",
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BOOT_MODE_PCR, result0));
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/* Extend the HWID Digest into PCR1 (GBB v1.2 and later only) */
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if (gbb && gbb->minor_version >= 2) {
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result1 = TlclExtend(HWID_DIGEST_PCR, gbb->hwid_digest,
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out_digest);
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VBDEBUG(("TPM: SetTPMBootModeState HWID PCR%d result %d\n",
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HWID_DIGEST_PCR, result1));
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}
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/* The caller only looks for nonzero results, not error codes. */
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return result0 || result1;
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}
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