vboot/firmware/lib/tpm_lite/tlcl.c

/* Copyright (c) 2012 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.
 */

/* A lightweight TPM command library.
 *
 * The general idea is that TPM commands are array of bytes whose
 * fields are mostly compile-time constant.  The goal is to build much
 * of the commands at compile time (or build time) and change some of
 * the fields at run time as needed.  The code in
 * utility/tlcl_generator.c builds structures containing the commands,
 * as well as the offsets of the fields that need to be set at run
 * time.
 */

#include "2sysincludes.h"
#include "2common.h"

#include "sysincludes.h"
#include "tlcl.h"
#include "tlcl_internal.h"
#include "tlcl_structures.h"
#include "utility.h"
#include "vboot_api.h"

#ifdef FOR_TEST
/* Allow unit testing implementation of TlclSendReceive() */
#undef CHROMEOS_ENVIRONMENT
#endif

/* Sets the size field of a TPM command. */
static inline void SetTpmCommandSize(uint8_t* buffer, uint32_t size)
{
	ToTpmUint32(buffer + sizeof(uint16_t), size);
}

/* Gets the size field of a TPM command. */
__attribute__((unused))
static inline int TpmCommandSize(const uint8_t* buffer)
{
	uint32_t size;
	FromTpmUint32(buffer + sizeof(uint16_t), &size);
	return (int) size;
}

/* Gets the size field of a TPM request or response. */
int TlclPacketSize(const uint8_t* packet)
{
	return TpmCommandSize(packet);
}

/* Gets the code field of a TPM command. */
static inline int TpmCommandCode(const uint8_t* buffer)
{
	uint32_t code;
	FromTpmUint32(buffer + sizeof(uint16_t) + sizeof(uint32_t), &code);
	return code;
}

/* Gets the return code field of a TPM result. */
static inline int TpmReturnCode(const uint8_t* buffer)
{
	return TpmCommandCode(buffer);
}

/* Like TlclSendReceive below, but do not retry if NEEDS_SELFTEST or
 * DOING_SELFTEST errors are returned.
 */
static uint32_t TlclSendReceiveNoRetry(const uint8_t* request,
                                       uint8_t* response, int max_length)
{

	uint32_t response_length = max_length;
	uint32_t result;

#ifdef EXTRA_LOGGING
	VB2_DEBUG("TPM: command: %x%x %x%x%x%x %x%x%x%x\n",
		  request[0], request[1],
		  request[2], request[3], request[4], request[5],
		  request[6], request[7], request[8], request[9]);
#endif

	result = VbExTpmSendReceive(request, TpmCommandSize(request),
				    response, &response_length);
	if (0 != result) {
		/* Communication with TPM failed, so response is garbage */
		VB2_DEBUG("TPM: command 0x%x send/receive failed: 0x%x\n",
			  TpmCommandCode(request), result);
		return result;
	}
	/* Otherwise, use the result code from the response */
	result = TpmReturnCode(response);

	/* TODO: add paranoia about returned response_length vs. max_length
	 * (and possibly expected length from the response header).  See
	 * crosbug.com/17017 */

#ifdef EXTRA_LOGGING
	VB2_DEBUG("TPM: response: %x%x %x%x%x%x %x%x%x%x\n",
		  response[0], response[1],
		  response[2], response[3], response[4], response[5],
		  response[6], response[7], response[8], response[9]);
#endif

	VB2_DEBUG("TPM: command 0x%x returned 0x%x\n",
		  TpmCommandCode(request), result);

	return result;
}

/* Sends a TPM command and gets a response.  Returns 0 if success or the TPM
 * error code if error. In the firmware, waits for the self test to complete
 * if needed. In the host, reports the first error without retries. */
uint32_t TlclSendReceive(const uint8_t* request, uint8_t* response,
                         int max_length)
{
	uint32_t result = TlclSendReceiveNoRetry(request, response, max_length);
	/* When compiling for the firmware, hide command failures due to the
	 * self test not having run or completed. */
#ifndef CHROMEOS_ENVIRONMENT
	/* If the command fails because the self test has not completed, try it
	 * again after attempting to ensure that the self test has completed. */
	if (result == TPM_E_NEEDS_SELFTEST || result == TPM_E_DOING_SELFTEST) {
		result = TlclContinueSelfTest();
		if (result != TPM_SUCCESS) {
			return result;
		}
#if defined(TPM_BLOCKING_CONTINUESELFTEST) || defined(VB_RECOVERY_MODE)
		/* Retry only once */
		result = TlclSendReceiveNoRetry(request, response, max_length);
#else
		/* This needs serious testing.  The TPM specification says:
		 * "iii. The caller MUST wait for the actions of
		 * TPM_ContinueSelfTest to complete before reissuing the
		 * command C1."  But, if ContinueSelfTest is non-blocking, how
		 * do we know that the actions have completed other than trying
		 * again? */
		do {
			result = TlclSendReceiveNoRetry(request, response,
							max_length);
		} while (result == TPM_E_DOING_SELFTEST);
#endif
	}
#endif  /* ! defined(CHROMEOS_ENVIRONMENT) */
	return result;
}

/* Sends a command and returns the error code. */
static uint32_t Send(const uint8_t* command)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	return TlclSendReceive(command, response, sizeof(response));
}

/* Exported functions. */

uint32_t TlclLibInit(void)
{
	return VbExTpmInit();
}

uint32_t TlclLibClose(void)
{
	return VbExTpmClose();
}

uint32_t TlclStartup(void)
{
	VB2_DEBUG("TPM: Startup\n");
	return Send(tpm_startup_cmd.buffer);
}

uint32_t TlclSaveState(void)
{
	VB2_DEBUG("TPM: SaveState\n");
	return Send(tpm_savestate_cmd.buffer);
}

uint32_t TlclResume(void)
{
	VB2_DEBUG("TPM: Resume\n");
	return Send(tpm_resume_cmd.buffer);
}

uint32_t TlclSelfTestFull(void)
{
	VB2_DEBUG("TPM: Self test full\n");
	return Send(tpm_selftestfull_cmd.buffer);
}

uint32_t TlclContinueSelfTest(void)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	VB2_DEBUG("TPM: Continue self test\n");
	/* Call the No Retry version of SendReceive to avoid recursion. */
	return TlclSendReceiveNoRetry(tpm_continueselftest_cmd.buffer,
				      response, sizeof(response));
}

uint32_t TlclDefineSpace(uint32_t index, uint32_t perm, uint32_t size)
{
	struct s_tpm_nv_definespace_cmd cmd;
	VB2_DEBUG("TPM: TlclDefineSpace(0x%x, 0x%x, %d)\n", index, perm, size);
	memcpy(&cmd, &tpm_nv_definespace_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_nv_definespace_cmd.index, index);
	ToTpmUint32(cmd.buffer + tpm_nv_definespace_cmd.perm, perm);
	ToTpmUint32(cmd.buffer + tpm_nv_definespace_cmd.size, size);
	return Send(cmd.buffer);
}

uint32_t TlclWrite(uint32_t index, const void* data, uint32_t length)
{
	struct s_tpm_nv_write_cmd cmd;
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	const int total_length =
			kTpmRequestHeaderLength + kWriteInfoLength + length;

	VB2_DEBUG("TPM: TlclWrite(0x%x, %d)\n", index, length);
	memcpy(&cmd, &tpm_nv_write_cmd, sizeof(cmd));
	VbAssert(total_length <= TPM_LARGE_ENOUGH_COMMAND_SIZE);
	SetTpmCommandSize(cmd.buffer, total_length);

	ToTpmUint32(cmd.buffer + tpm_nv_write_cmd.index, index);
	ToTpmUint32(cmd.buffer + tpm_nv_write_cmd.length, length);
	memcpy(cmd.buffer + tpm_nv_write_cmd.data, data, length);

	return TlclSendReceive(cmd.buffer, response, sizeof(response));
}

uint32_t TlclRead(uint32_t index, void* data, uint32_t length)
{
	struct s_tpm_nv_read_cmd cmd;
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t result_length;
	uint32_t result;

	VB2_DEBUG("TPM: TlclRead(0x%x, %d)\n", index, length);
	memcpy(&cmd, &tpm_nv_read_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_nv_read_cmd.index, index);
	ToTpmUint32(cmd.buffer + tpm_nv_read_cmd.length, length);

	result = TlclSendReceive(cmd.buffer, response, sizeof(response));
	if (result == TPM_SUCCESS && length > 0) {
		uint8_t* nv_read_cursor = response + kTpmResponseHeaderLength;
		FromTpmUint32(nv_read_cursor, &result_length);
		if (result_length > length)
			result_length = length;  /* Truncate to fit buffer */
		nv_read_cursor += sizeof(uint32_t);
		memcpy(data, nv_read_cursor, result_length);
	}

	return result;
}

uint32_t TlclPCRRead(uint32_t index, void* data, uint32_t length)
{
	struct s_tpm_pcr_read_cmd cmd;
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t result;

	VB2_DEBUG("TPM: TlclPCRRead(0x%x, %d)\n", index, length);
	if (length < kPcrDigestLength) {
		return TPM_E_IOERROR;
	}
	memcpy(&cmd, &tpm_pcr_read_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_pcr_read_cmd.pcrNum, index);

	result = TlclSendReceive(cmd.buffer, response, sizeof(response));
	if (result == TPM_SUCCESS) {
		uint8_t* pcr_read_cursor = response + kTpmResponseHeaderLength;
		memcpy(data, pcr_read_cursor, kPcrDigestLength);
	}

	return result;
}

uint32_t TlclWriteLock(uint32_t index)
{
	VB2_DEBUG("TPM: Write lock 0x%x\n", index);
	return TlclWrite(index, NULL, 0);
}

uint32_t TlclReadLock(uint32_t index)
{
	VB2_DEBUG("TPM: Read lock 0x%x\n", index);
	return TlclRead(index, NULL, 0);
}

uint32_t TlclAssertPhysicalPresence(void)
{
	VB2_DEBUG("TPM: Asserting physical presence\n");
	return Send(tpm_ppassert_cmd.buffer);
}

uint32_t TlclPhysicalPresenceCMDEnable(void)
{
	VB2_DEBUG("TPM: Enable the physical presence command\n");
	return Send(tpm_ppenable_cmd.buffer);
}

uint32_t TlclFinalizePhysicalPresence(void)
{
	VB2_DEBUG("TPM: Enable PP cmd, disable HW pp, and set lifetime lock\n");
	return Send(tpm_finalizepp_cmd.buffer);
}

uint32_t TlclAssertPhysicalPresenceResult(void)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	return TlclSendReceive(tpm_ppassert_cmd.buffer, response,
			       sizeof(response));
}

uint32_t TlclLockPhysicalPresence(void)
{
	VB2_DEBUG("TPM: Lock physical presence\n");
	return Send(tpm_pplock_cmd.buffer);
}

uint32_t TlclSetNvLocked(void)
{
	VB2_DEBUG("TPM: Set NV locked\n");
	return TlclDefineSpace(TPM_NV_INDEX_LOCK, 0, 0);
}

int TlclIsOwned(void)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE + TPM_PUBEK_SIZE];
	uint32_t result;
	result = TlclSendReceive(tpm_readpubek_cmd.buffer,
				 response, sizeof(response));
	return (result != TPM_SUCCESS);
}

uint32_t TlclForceClear(void)
{
	VB2_DEBUG("TPM: Force clear\n");
	return Send(tpm_forceclear_cmd.buffer);
}

uint32_t TlclSetEnable(void)
{
	VB2_DEBUG("TPM: Enabling TPM\n");
	return Send(tpm_physicalenable_cmd.buffer);
}

uint32_t TlclClearEnable(void)
{
	VB2_DEBUG("TPM: Disabling TPM\n");
	return Send(tpm_physicaldisable_cmd.buffer);
}

uint32_t TlclSetDeactivated(uint8_t flag)
{
	struct s_tpm_physicalsetdeactivated_cmd cmd;
	VB2_DEBUG("TPM: SetDeactivated(%d)\n", flag);
	memcpy(&cmd, &tpm_physicalsetdeactivated_cmd, sizeof(cmd));
	*(cmd.buffer + cmd.deactivated) = flag;
	return Send(cmd.buffer);
}

uint32_t TlclGetPermanentFlags(TPM_PERMANENT_FLAGS* pflags)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t size;
	uint32_t result = TlclSendReceive(tpm_getflags_cmd.buffer, response,
					  sizeof(response));
	if (result != TPM_SUCCESS)
		return result;
	FromTpmUint32(response + kTpmResponseHeaderLength, &size);
	/* TODO(crbug.com/379255): This fails. Find out why.
	 * VbAssert(size == sizeof(TPM_PERMANENT_FLAGS));
	 */
	memcpy(pflags,
	       response + kTpmResponseHeaderLength + sizeof(size),
	       sizeof(TPM_PERMANENT_FLAGS));
	return result;
}

uint32_t TlclGetSTClearFlags(TPM_STCLEAR_FLAGS* vflags)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t size;
	uint32_t result = TlclSendReceive(tpm_getstclearflags_cmd.buffer,
					  response, sizeof(response));
	if (result != TPM_SUCCESS)
		return result;
	FromTpmUint32(response + kTpmResponseHeaderLength, &size);
	/* Ugly assertion, but the struct is padded up by one byte. */
	/* TODO(crbug.com/379255): This fails. Find out why.
	 * VbAssert(size == 7 && sizeof(TPM_STCLEAR_FLAGS) - 1 == 7);
	 */
	memcpy(vflags,
	       response + kTpmResponseHeaderLength + sizeof(size),
	       sizeof(TPM_STCLEAR_FLAGS));
	return result;
}

uint32_t TlclGetFlags(uint8_t* disable,
                      uint8_t* deactivated,
                      uint8_t *nvlocked)
{
	TPM_PERMANENT_FLAGS pflags;
	uint32_t result = TlclGetPermanentFlags(&pflags);
	if (result == TPM_SUCCESS) {
		if (disable)
			*disable = pflags.disable;
		if (deactivated)
			*deactivated = pflags.deactivated;
		if (nvlocked)
			*nvlocked = pflags.nvLocked;
		VB2_DEBUG("TPM: Got flags disable=%d, deactivated=%d, "
			  "nvlocked=%d\n",
			  pflags.disable, pflags.deactivated, pflags.nvLocked);
	}
	return result;
}

uint32_t TlclSetGlobalLock(void)
{
	uint32_t x;
	VB2_DEBUG("TPM: Set global lock\n");
	return TlclWrite(TPM_NV_INDEX0, (uint8_t*) &x, 0);
}

uint32_t TlclExtend(int pcr_num, const uint8_t* in_digest,
                    uint8_t* out_digest)
{
	struct s_tpm_extend_cmd cmd;
	uint8_t response[kTpmResponseHeaderLength + kPcrDigestLength];
	uint32_t result;

	memcpy(&cmd, &tpm_extend_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_extend_cmd.pcrNum, pcr_num);
	memcpy(cmd.buffer + cmd.inDigest, in_digest, kPcrDigestLength);

	result = TlclSendReceive(cmd.buffer, response, sizeof(response));
	if (result != TPM_SUCCESS)
		return result;

	memcpy(out_digest, response + kTpmResponseHeaderLength,
	       kPcrDigestLength);
	return result;
}

uint32_t TlclGetPermissions(uint32_t index, uint32_t* permissions)
{
	struct s_tpm_getpermissions_cmd cmd;
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint8_t* nvdata;
	uint32_t result;
	uint32_t size;

	memcpy(&cmd, &tpm_getpermissions_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_getpermissions_cmd.index, index);
	result = TlclSendReceive(cmd.buffer, response, sizeof(response));
	if (result != TPM_SUCCESS)
		return result;

	nvdata = response + kTpmResponseHeaderLength + sizeof(size);
	FromTpmUint32(nvdata + kNvDataPublicPermissionsOffset, permissions);
	return result;
}

uint32_t TlclGetOwnership(uint8_t* owned)
{
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t size;
	uint32_t result = TlclSendReceive(tpm_getownership_cmd.buffer,
					  response, sizeof(response));
	if (result != TPM_SUCCESS)
		return result;
	FromTpmUint32(response + kTpmResponseHeaderLength, &size);
	/* TODO(crbug.com/379255): This fails. Find out why.
	 * VbAssert(size == sizeof(*owned));
	 */
	memcpy(owned,
	       response + kTpmResponseHeaderLength + sizeof(size),
	       sizeof(*owned));
	return result;
}

uint32_t TlclGetRandom(uint8_t* data, uint32_t length, uint32_t *size)
{
	struct s_tpm_get_random_cmd cmd;
	uint8_t response[TPM_LARGE_ENOUGH_COMMAND_SIZE];
	uint32_t result;

	VB2_DEBUG("TPM: TlclGetRandom(%d)\n", length);
	memcpy(&cmd, &tpm_get_random_cmd, sizeof(cmd));
	ToTpmUint32(cmd.buffer + tpm_get_random_cmd.bytesRequested, length);
	/* There must be room in the response buffer for the bytes. */
	if (length > TPM_LARGE_ENOUGH_COMMAND_SIZE - kTpmResponseHeaderLength
	    - sizeof(uint32_t)) {
		return TPM_E_IOERROR;
	}

	result = TlclSendReceive(cmd.buffer, response, sizeof(response));
	if (result == TPM_SUCCESS) {
		uint8_t* get_random_cursor;
		FromTpmUint32(response + kTpmResponseHeaderLength, size);

		/* There must be room in the target buffer for the bytes. */
		if (*size > length) {
			return TPM_E_RESPONSE_TOO_LARGE;
		}
		get_random_cursor = response + kTpmResponseHeaderLength
				+ sizeof(uint32_t);
		memcpy(data, get_random_cursor, *size);
	}

	return result;
}