githubmirror/libtpms

src/tpm2/ExecCommand.c
327 строк15 KB
Stefan Berger
tpm2: ExecuteCommand: Handle unreasonably large command sizes
26 авг 2023, 05:57
26 авг 2023, 05:57c235a90
/********************************************************************************/
/*										*/
/*			     ExecCommand					*/
/*			     Written by Ken Goldman				*/
/*		       IBM Thomas J. Watson Research Center			*/
/*										*/
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/********************************************************************************/

/* 6.2 ExecCommand.c */
/* This file contains the entry function ExecuteCommand() which provides the main control flow for
   TPM command execution. */
#include "Tpm.h"
#include "ExecCommand_fp.h"

#define TPM_HAVE_TPM2_DECLARATIONS
#include "tpm_library_intern.h"  // libtpms added

/* Uncomment this next #include if doing static command/response buffer sizing */
// #include "CommandResponseSizes_fp.h"
// The function performs the following steps.
// a)	Parses the command header from input buffer.
// b)	Calls ParseHandleBuffer() to parse the handle area of the command.
//     c)	Validates that each of the handles references a loaded entity.
//     d)	Calls ParseSessionBuffer() () to:
// 1)	unmarshal and parse the session area;
// 2)	check the authorizations; and
// 3)	when necessary, decrypt a parameter.
//       e)	Calls CommandDispatcher() to:
// 1)	unmarshal the command parameters from the command buffer;
// 2)	call the routine that performs the command actions; and
// 3)	marshal the responses into the response buffer.
// f)	If any error occurs in any of the steps above create the error response and return.
// g)	Calls BuildResponseSession() to:
// 1)	when necessary, encrypt a parameter
//       2)	build the response authorization sessions
//       3)	update the audit sessions and nonces
//       h)	Calls BuildResponseHeader() to complete the construction of the response.

// 	  responseSize is set by the caller to the maximum number of bytes available in the output
// 	  buffer. ExecuteCommand() will adjust the value and return the number of bytes placed in
// 	  the buffer.
// 	  response is also set by the caller to indicate the buffer into which ExecuteCommand() is
// 	  to place the response.
// 	  request and response may point to the same buffer
// 	  NOTE: As of February, 2016, the failure processing has been moved to the platform-specific
// 	  code. When the TPM code encounters an unrecoverable failure, it will SET g_inFailureMode
// 	  and call _plat__Fail(). That function should not return but may call ExecuteCommand().
LIB_EXPORT void
ExecuteCommand(
	       uint32_t         requestSize,   // IN: command buffer size
	       unsigned char   *request,       // IN: command buffer
	       uint32_t        *responseSize,  // IN/OUT: response buffer size
	       unsigned char   **response      // IN/OUT: response buffer
	       )
{
    // Command local variables
    UINT32               commandSize;
    COMMAND              command;
    // Response local variables
    UINT32               maxResponse = *responseSize;
    TPM_RC               result;            // return code for the command

    /* check for an unreasonably large command size, since it's cast to a signed integer later */
    if (requestSize > INT32_MAX) {
	result = TPM_RC_SUCCESS;
	goto Cleanup;
    }
    // This next function call is used in development to size the command and response
    // buffers. The values printed are the sizes of the internal structures and
    // not the sizes of the canonical forms of he command response structures. Also,
    // the sizes do not include the tag, command.code, requestSize, or the authorization
    // fields.
    //CommandResponseSizes();
    // Set flags for NV access state. This should happen before any other
    // operation that may require a NV write. Note, that this needs to be done
    // even when in failure mode. Otherwise, g_updateNV would stay SET while in
    // Failure mode and the NV would be written on each call.
    g_updateNV = UT_NONE;
    g_clearOrderly = FALSE;
    if(g_inFailureMode)
	{
	    // Do failure mode processing
	    TpmFailureMode(requestSize, request, responseSize, response);
	    return;
	}
    // Query platform to get the NV state.  The result state is saved internally
    // and will be reported by NvIsAvailable(). The reference code requires that
    // accessibility of NV does not change during the execution of a command.
    // Specifically, if NV is available when the command execution starts and then
    // is not available later when it is necessary to write to NV, then the TPM
    // will go into failure mode.
    NvCheckState();
    // Due to the limitations of the simulation, TPM clock must be explicitly
    // synchronized with the system clock whenever a command is received.
    // This function call is not necessary in a hardware TPM. However, taking
    // a snapshot of the hardware timer at the beginning of the command allows
    // the time value to be consistent for the duration of the command execution.
    TimeUpdateToCurrent();
    // Any command through this function will unceremoniously end the
    // _TPM_Hash_Data/_TPM_Hash_End sequence.
    if(g_DRTMHandle != TPM_RH_UNASSIGNED)
	ObjectTerminateEvent();
    // Get command buffer size and command buffer.
    command.tag = 0;				// libtpms added: Coverity
    command.parameterBuffer = request;
    command.parameterSize = requestSize;
    // Parse command header: tag, commandSize and command.code.
    // First parse the tag. The unmarshaling routine will validate
    // that it is either TPM_ST_SESSIONS or TPM_ST_NO_SESSIONS.
    result = TPMI_ST_COMMAND_TAG_Unmarshal(&command.tag,
					   &command.parameterBuffer,
					   &command.parameterSize);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // Unmarshal the commandSize indicator.
    result = UINT32_Unmarshal(&commandSize,
			      &command.parameterBuffer,
			      &command.parameterSize);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // On a TPM that receives bytes on a port, the number of bytes that were
    // received on that port is requestSize it must be identical to commandSize.
    // In addition, commandSize must not be larger than MAX_COMMAND_SIZE allowed
    // by the implementation. The check against MAX_COMMAND_SIZE may be redundant
    // as the input processing (the function that receives the command bytes and
    // places them in the input buffer) would likely have the input truncated when
    // it reaches MAX_COMMAND_SIZE, and requestSize would not equal commandSize.
    if(commandSize != requestSize || commandSize > MAX_COMMAND_SIZE)
	{
	    result = TPM_RC_COMMAND_SIZE;
	    goto Cleanup;
	}
    // Unmarshal the command code.
    result = TPM_CC_Unmarshal(&command.code, &command.parameterBuffer,
			      &command.parameterSize);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // Check to see if the command is implemented.
    command.index = CommandCodeToCommandIndex(command.code);
    if(UNIMPLEMENTED_COMMAND_INDEX == command.index)
	{
	    result = TPM_RC_COMMAND_CODE;
	    goto Cleanup;
	}
#if  FIELD_UPGRADE_IMPLEMENTED  == YES
    // If the TPM is in FUM, then the only allowed command is
    // TPM_CC_FieldUpgradeData.
    if(IsFieldUgradeMode() && (command.code != TPM_CC_FieldUpgradeData))
	{
	    result = TPM_RC_UPGRADE;
	    goto Cleanup;
	}
    else
#endif
	// Excepting FUM, the TPM only accepts TPM2_Startup() after
	// _TPM_Init. After getting a TPM2_Startup(), TPM2_Startup()
	// is no longer allowed.
	if((!TPMIsStarted() && command.code != TPM_CC_Startup)
	   || (TPMIsStarted() && command.code == TPM_CC_Startup))
	    {
		result = TPM_RC_INITIALIZE;
		goto Cleanup;
	    }
    // Start regular command process.
    NvIndexCacheInit();
    // Parse Handle buffer.
    result = ParseHandleBuffer(&command);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // All handles in the handle area are required to reference TPM-resident
    // entities.
    result = EntityGetLoadStatus(&command);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // Authorization session handling for the command.
    ClearCpRpHashes(&command);
    if(command.tag == TPM_ST_SESSIONS)
	{
	    // Find out session buffer size.
	    result = UINT32_Unmarshal((UINT32 *)&command.authSize,
				      &command.parameterBuffer,
				      &command.parameterSize);
	    if(result != TPM_RC_SUCCESS)
		goto Cleanup;
	    // Perform sanity check on the unmarshaled value. If it is smaller than
	    // the smallest possible session or larger than the remaining size of
	    // the command, then it is an error. NOTE: This check could pass but the
	    // session size could still be wrong. That will be determined after the
	    // sessions are unmarshaled.
	    if(command.authSize < 9
	       || command.authSize > command.parameterSize)
		{
		    result = TPM_RC_SIZE;
		    goto Cleanup;
		}
	    command.parameterSize -= command.authSize;
	    // The actions of ParseSessionBuffer() are described in the introduction.
	    // As the sessions are parsed command.parameterBuffer is advanced so, on a
	    // successful return, command.parameterBuffer should be pointing at the
	    // first byte of the parameters.
	    result = ParseSessionBuffer(&command);
	    if(result != TPM_RC_SUCCESS)
		goto Cleanup;
	}
    else
	{
	    command.authSize = 0;
	    // The command has no authorization sessions.
	    // If the command requires authorizations, then CheckAuthNoSession() will
	    // return an error.
	    result = CheckAuthNoSession(&command);
	    if(result != TPM_RC_SUCCESS)
		goto Cleanup;
	}
    // Set up the response buffer pointers. CommandDispatch will marshal the
    // response parameters starting at the address in command.responseBuffer.
    //    *response = MemoryGetResponseBuffer(command.index);
    // leave space for the command header
    command.responseBuffer = *response + STD_RESPONSE_HEADER;
    // leave space for the parameter size field if needed
    if(command.tag == TPM_ST_SESSIONS)
	command.responseBuffer += sizeof(UINT32);
    if(IsHandleInResponse(command.index))
	command.responseBuffer += sizeof(TPM_HANDLE);
    // CommandDispatcher returns a response handle buffer and a response parameter
    // buffer if it succeeds. It will also set the parameterSize field in the
    // buffer if the tag is TPM_RC_SESSIONS.
    result = CommandDispatcher(&command);
    if(result != TPM_RC_SUCCESS)
	goto Cleanup;
    // Build the session area at the end of the parameter area.
    result = BuildResponseSession(&command);
    if(result != TPM_RC_SUCCESS)
	{
	    goto Cleanup;
	}
 Cleanup:
    if(g_clearOrderly == TRUE
       && NV_IS_ORDERLY)
	{
#if USE_DA_USED
	    gp.orderlyState = g_daUsed ? SU_DA_USED_VALUE : SU_NONE_VALUE;
#else
	    gp.orderlyState = SU_NONE_VALUE;
#endif
	    NV_SYNC_PERSISTENT(orderlyState);
	}
    // This implementation loads an "evict" object to a transient object slot in
    // RAM whenever an "evict" object handle is used in a command so that the
    // access to any object is the same. These temporary objects need to be
    // cleared from RAM whether the command succeeds or fails.
    ObjectCleanupEvict();
    // The parameters and sessions have been marshaled. Now tack on the header and
    // set the sizes
    BuildResponseHeader(&command, *response, result);
    // Try to commit all the writes to NV if any NV write happened during this
    // command execution. This check should be made for both succeeded and failed
    // commands, because a failed one may trigger a NV write in DA logic as well.
    // This is the only place in the command execution path that may call the NV
    // commit. If the NV commit fails, the TPM should be put in failure mode.
    if((g_updateNV != UT_NONE) && !g_inFailureMode)
	{
	    if(g_updateNV == UT_ORDERLY)
		NvUpdateIndexOrderlyData();
	    if(!NvCommit())
		FAIL(FATAL_ERROR_INTERNAL);
	    g_updateNV = UT_NONE;
	}
    pAssert((UINT32)command.parameterSize <= maxResponse);
    // Clear unused bits in response buffer.
    MemorySet(*response + *responseSize, 0, maxResponse - *responseSize);
    // as a final act, and not before, update the response size.
    *responseSize = (UINT32)command.parameterSize;
    return;
}