githubmirror/libtpms

src/tpm2/Time.c
287 строк11 KB
Stefan Berger
rev180: Sync _plat__ClockRateAdjust and adjust caller
04 янв 2024, 04:23
04 янв 2024, 04:23b1da8a1
/********************************************************************************/
/*										*/
/*		Functions relating to the TPM's time functions 	 		*/
/*			     Written by Ken Goldman				*/
/*		       IBM Thomas J. Watson Research Center			*/
/*										*/
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/********************************************************************************/

//** Introduction
// This file contains the functions relating to the TPM's time functions including
// the interface to the implementation-specific time functions.
//
//** Includes
#include "Tpm.h"
#include "Marshal.h"

//** Functions

//*** TimePowerOn()
// This function initialize time info at _TPM_Init().
//
// This function is called at _TPM_Init() so that the TPM time can start counting
// as soon as the TPM comes out of reset and doesn't have to wait until
// TPM2_Startup() in order to begin the new time epoch. This could be significant
// for systems that could get powered up but not run any TPM commands for some
// period of time.
//
void TimePowerOn(void)
{
    g_time = _plat__TimerRead();
}

//*** TimeNewEpoch()
// This function does the processing to generate a new time epoch nonce and
// set NV for update. This function is only called when NV is known to be available
// and the clock is running. The epoch is updated to persistent data.
static void TimeNewEpoch(void)
{
#if CLOCK_STOPS
    CryptRandomGenerate(sizeof(CLOCK_NONCE), (BYTE*)&g_timeEpoch);
#else
    // if the epoch is kept in NV, update it.
    gp.timeEpoch++;
    NV_SYNC_PERSISTENT(timeEpoch);
#endif
    // Clean out any lingering state
    _plat__TimerWasStopped();
}

//*** TimeStartup()
// This function updates the resetCount and restartCount components of
// TPMS_CLOCK_INFO structure at TPM2_Startup().
//
// This function will deal with the deferred creation of a new epoch.
// TimeUpdateToCurrent() will not start a new epoch even if one is due when
// TPM_Startup() has not been run. This is because the state of NV is not known
// until startup completes. When Startup is done, then it will create the epoch
// nonce to complete the initializations by calling this function.
BOOL TimeStartup(STARTUP_TYPE type  // IN: start up type
		 )
{
    NOT_REFERENCED(type);
    // If the previous cycle is orderly shut down, the value of the safe bit
    // the same as previously saved.  Otherwise, it is not safe.
    if(!NV_IS_ORDERLY)
	go.clockSafe = NO;
    return TRUE;
}

//*** TimeClockUpdate()
// This function updates go.clock. If 'newTime' requires an update of NV, then
// NV is checked for availability. If it is not available or is rate limiting, then
// go.clock is not updated and the function returns an error. If 'newTime' would
// not cause an NV write, then go.clock is updated. If an NV write occurs, then
// go.safe is SET.
void TimeClockUpdate(UINT64 newTime  // IN: New time value in mS.
		     )
{
#define CLOCK_UPDATE_MASK ((1ULL << NV_CLOCK_UPDATE_INTERVAL) - 1)

    // Check to see if the update will cause a need for an nvClock update
    if((newTime | CLOCK_UPDATE_MASK) > (go.clock | CLOCK_UPDATE_MASK))
	{
	    pAssert(g_NvStatus == TPM_RC_SUCCESS);

	    // Going to update the NV time state so SET the safe flag
	    go.clockSafe = YES;

	    // update the time
	    go.clock = newTime;

	    /* libtpms: Changing the clock alone does not cause the permanent
	     *          state to be written to storage, there must be other
	     *          reasons as well.
	     */
	    UPDATE_TYPE old_g_updateNV = g_updateNV;	// libtpms added

	    NvWrite(NV_ORDERLY_DATA, sizeof(go), &go);

	    g_updateNV = old_g_updateNV;		// libtpms added
	}
    else
	// No NV update needed so just update
	go.clock = newTime;
}

//*** TimeUpdate()
// This function is used to update the time and clock values. If the TPM
// has run TPM2_Startup(), this function is called at the start of each command.
// If the TPM has not run TPM2_Startup(), this is called from TPM2_Startup() to
// get the clock values initialized. It is not called on command entry because, in
// this implementation, the go structure is not read from NV until TPM2_Startup().
// The reason for this is that the initialization code (_TPM_Init()) may run before
// NV is accessible.
void TimeUpdate(void)
{
    UINT64 elapsed;
    //
    // Make sure that we consume the current _plat__TimerWasStopped() state.
    if(_plat__TimerWasStopped())
	{
	    TimeNewEpoch();
	}
    // Get the difference between this call and the last time we updated the tick
    // timer.
    elapsed = _plat__TimerRead() - g_time;
    // Don't read +
    g_time += elapsed;

    // Don't need to check the result because it has to be success because have
    // already checked that NV is available.
    TimeClockUpdate(go.clock + elapsed);

    // Call self healing logic for dictionary attack parameters
    DASelfHeal();
}

//*** TimeUpdateToCurrent()
// This function updates the 'Time' and 'Clock' in the global
// TPMS_TIME_INFO structure.
//
// In this implementation, 'Time' and 'Clock' are updated at the beginning
// of each command and the values are unchanged for the duration of the
// command.
//
// Because 'Clock' updates may require a write to NV memory, 'Time' and 'Clock'
// are not allowed to advance if NV is not available. When clock is not advancing,
// any function that uses 'Clock' will fail and return TPM_RC_NV_UNAVAILABLE or
// TPM_RC_NV_RATE.
//
// This implementation does not do rate limiting. If the implementation does do
// rate limiting, then the 'Clock' update should not be inhibited even when doing
// rate limiting.
void TimeUpdateToCurrent(void)
{
    // Can't update time during the dark interval or when rate limiting so don't
    // make any modifications to the internal clock value. Also, defer any clock
    // processing until TPM has run TPM2_Startup()
    if(!NV_IS_AVAILABLE || !TPMIsStarted())
	return;

    TimeUpdate();
}

//*** TimeSetAdjustRate()
// This function is used to perform rate adjustment on 'Time' and 'Clock'.
void TimeSetAdjustRate(TPM_CLOCK_ADJUST adjust  // IN: adjust constant
		       )
{
    switch(adjust)
	{
	  case TPM_CLOCK_COARSE_SLOWER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_COARSE_SLOWER);
	    break;
	  case TPM_CLOCK_COARSE_FASTER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_COARSE_FASTER);
	    break;
	  case TPM_CLOCK_MEDIUM_SLOWER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_MEDIUM_SLOWER);
	    break;
	  case TPM_CLOCK_MEDIUM_FASTER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_MEDIUM_FASTER);
	    break;
	  case TPM_CLOCK_FINE_SLOWER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_FINE_SLOWER);
	    break;
	  case TPM_CLOCK_FINE_FASTER:
	    _plat__ClockRateAdjust(PLAT_TPM_CLOCK_ADJUST_FINE_FASTER);
	    break;
	  case TPM_CLOCK_NO_CHANGE:
	    break;
	  default:
	    // should have been blocked sooner
	    FAIL(FATAL_ERROR_INTERNAL);
	    break;
	}

    return;
}

//*** TimeGetMarshaled()
// This function is used to access TPMS_TIME_INFO in canonical form.
// The function collects the time information and marshals it into 'dataBuffer'
// and returns the marshaled size
UINT16
TimeGetMarshaled(TIME_INFO* dataBuffer  // OUT: result buffer
		 )
{
    TPMS_TIME_INFO timeInfo;

    // Fill TPMS_TIME_INFO structure
    timeInfo.time = g_time;
    TimeFillInfo(&timeInfo.clockInfo);

    // Marshal TPMS_TIME_INFO to canonical form
    return TPMS_TIME_INFO_Marshal(&timeInfo, (BYTE**)&dataBuffer, NULL);
}

//*** TimeFillInfo
// This function gathers information to fill in a TPMS_CLOCK_INFO structure.
void TimeFillInfo(TPMS_CLOCK_INFO* clockInfo)
{
    clockInfo->clock        = go.clock;
    clockInfo->resetCount   = gp.resetCount;
    clockInfo->restartCount = gr.restartCount;

    // If NV is not available, clock stopped advancing and the value reported is
    // not "safe".
    if(NV_IS_AVAILABLE)
	clockInfo->safe = go.clockSafe;
    else
	clockInfo->safe = NO;

    return;
}