/********************************************************************************/
/*										*/
/*			 NV read and write access methods			*/
/*			     Written by Ken Goldman				*/
/*		       IBM Thomas J. Watson Research Center			*/
/*            $Id: NVMem.c 1658 2021-01-22 23:14:01Z kgoldman $			*/
/*										*/
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/********************************************************************************/

/* C.6 NVMem.c */
/* C.6.1. Description */
/* This file contains the NV read and write access methods.  This implementation uses RAM/file and
   does not manage the RAM/file as NV blocks. The implementation may become more sophisticated over
   time. */
/* C.6.2. Includes and Local */
#include <memory.h>
#include <string.h>
#include <assert.h>
#include "Platform.h"
#if FILE_BACKED_NV
#   include         <stdio.h>
static FILE                *s_NvFile = NULL;		/* kgold made these static */
static int                 s_NeedsManufacture = FALSE;
#endif

/* C.6.2. Functions */
/* C.6.2.1.	NvFileOpen() */

#if FILE_BACKED_NV

/* This function opens the file used to hold the NV image.
   Return Type: int */
/* Return Value	Meaning */
/* >=0	success */
/* -1	error */
static int
NvFileOpen(
	   const char      *mode
	   )
{
#if defined(NV_FILE_PATH)
#   define TO_STRING(s) TO_STRING_IMPL(s)
#   define TO_STRING_IMPL(s) #s
    const char* s_NvFilePath = TO_STRING(NV_FILE_PATH);
#   undef TO_STRING
#   undef TO_STRING_IMPL
#else
    const char* s_NvFilePath = "NVChip";
#endif

    // Try to open an exist NVChip file for read/write
#   if defined _MSC_VER && 1
    if(fopen_s(&s_NvFile, s_NvFilePath, mode) != 0)
	s_NvFile = NULL;
#   else
    s_NvFile = fopen(s_NvFilePath, mode);
#   endif
    return (s_NvFile == NULL) ? -1 : 0;
}

/* C.6.2.2.	NvFileCommit() */
/* Write all of the contents of the NV image to a file. */
/* Return Value	Meaning */
/* TRUE	success */
/* FALSE failure */
static int
NvFileCommit(
	     void
	     	)
{
    int         OK;
    // If NV file is not available, return failure
    if(s_NvFile == NULL)
	return 1;
    // Write RAM data to NV
    fseek(s_NvFile, 0, SEEK_SET);
    OK = (NV_MEMORY_SIZE == fwrite(s_NV, 1, NV_MEMORY_SIZE, s_NvFile));
    OK = OK && (0 == fflush(s_NvFile));
    assert(OK);
    return OK;
}
/* C.6.2.3.	NvFileSize() */
/* This function gets the size of the NV file and puts the file pointer where desired using the seek
   method values. SEEK_SET => beginning; SEEK_CUR => current position and SEEK_END => to the end of
   the file. */
static long
NvFileSize(
	   int         leaveAt
	   )
{
    int		irc;	/* kgold, added return code checks */
    long    fileSize;
    long    filePos = ftell(s_NvFile);
    //
    assert(NULL != s_NvFile);

    int fseek_result = fseek(s_NvFile, 0, SEEK_END);
    NOT_REFERENCED(fseek_result); // Fix compiler warning for NDEBUG
    assert(fseek_result == 0);
    fileSize = ftell(s_NvFile);
    assert(fileSize >= 0);
    switch(leaveAt)
	{
	  case SEEK_SET:
	    filePos = 0;
	  case SEEK_CUR:
	    irc = fseek(s_NvFile, filePos, SEEK_SET);
	    assert(irc == 0);
	    break;
	  case SEEK_END:
	    break;
	  default:
	    assert(FALSE);
	    break;
	}
    return fileSize;
}
#endif

/* C.6.2.4. _plat__NvErrors() */
/* This function is used by the simulator to set the error flags in the NV subsystem to simulate an
   error in the NV loading process */
LIB_EXPORT void
_plat__NvErrors(
		int              recoverable,
		int            unrecoverable
		)
{
    s_NV_unrecoverable = unrecoverable;
    s_NV_recoverable = recoverable;
}
/* C.6.2.5. _plat__NVEnable() */
/* Enable NV memory. */
/* This version just pulls in data from a file. In a real TPM, with NV on chip, this function would
   verify the integrity of the saved context. If the NV memory was not on chip but was in something
   like RPMB, the NV state would be read in, decrypted and integrity checked. */
/* The recovery from an integrity failure depends on where the error occurred. It it was in the
   state that is discarded by TPM Reset, then the error is recoverable if the TPM is
   reset. Otherwise, the TPM must go into failure mode. */
/* Return Values Meaning */
/* 0 if success */
/* > 0 if receive recoverable error */
/* <0 if unrecoverable error */
LIB_EXPORT int
_plat__NVEnable(
		void            *platParameter  // IN: platform specific parameters
		)
{
    NOT_REFERENCED(platParameter);          // to keep compiler quiet
    //
    // Start assuming everything is OK
    s_NV_unrecoverable = FALSE;
    s_NV_recoverable = FALSE;
#if FILE_BACKED_NV
    if(s_NvFile != NULL)
	return 0;
    // Initialize all the bytes in the ram copy of the NV
    _plat__NvMemoryClear(0, NV_MEMORY_SIZE);
    
    // If the file exists
    if(NvFileOpen("r+b") >= 0)
	{
	    long    fileSize = NvFileSize(SEEK_SET);    // get the file size and leave the
	    // file pointer at the start
	    //
	    // If the size is right, read the data
	    if(NV_MEMORY_SIZE == fileSize)
		{
		    s_NeedsManufacture =
			fread(s_NV, 1, NV_MEMORY_SIZE, s_NvFile) != NV_MEMORY_SIZE;
		}
	    else
		{
		    NvFileCommit();     // for any other size, initialize it
		    s_NeedsManufacture = TRUE;
		}
	}
    // If NVChip file does not exist, try to create it for read/write.
    else if(NvFileOpen("w+b") >= 0)
	{
	    NvFileCommit();             // Initialize the file
	    s_NeedsManufacture = TRUE;
	}
    assert(NULL != s_NvFile);       // Just in case we are broken for some reason.
#endif
    // NV contents have been initialized and the error checks have been performed. For
    // simulation purposes, use the signaling interface to indicate if an error is
    // to be simulated and the type of the error.
    if(s_NV_unrecoverable)
	return -1;
    return s_NV_recoverable;
}

/* C.6.2.6. _plat__NVDisable() */
/* Disable NV memory */
LIB_EXPORT void
_plat__NVDisable(
		 int             delete           // IN: If TRUE, delete the NV contents.
		 )
{
#if  FILE_BACKED_NV
    if(NULL != s_NvFile)
	{
	    fclose(s_NvFile);    // Close NV file
	    // Alternative to deleting the file is to set its size to 0. This will not
	    // match the NV size so the TPM will need to be remanufactured.
	    if(delete)
		{
		    // Open for writing at the start. Sets the size to zero.
		    if(NvFileOpen("w") >= 0)
			{
			    fflush(s_NvFile);
			    fclose(s_NvFile);
			}
		}
	}
    s_NvFile = NULL;        // Set file handle to NULL
#endif
    return;
}

/* C.6.2.7. _plat__IsNvAvailable() */
/* Check if NV is available */
/* Return Values Meaning */
/* 0 NV is available */
/* 1 NV is not available due to write failure */
/* 2 NV is not available due to rate limit */
LIB_EXPORT int
_plat__IsNvAvailable(
		     void
		     )
{
    int         retVal = 0;
    // NV is not available if the TPM is in failure mode
    if(!s_NvIsAvailable)
	retVal = 1;
#if FILE_BACKED_NV
    else
	retVal = (s_NvFile == NULL);
#endif
    return retVal;
}

/* C.6.2.8. _plat__NvMemoryRead() */
/* Function: Read a chunk of NV memory */
LIB_EXPORT void
_plat__NvMemoryRead(
		    unsigned int     startOffset,   // IN: read start
		    unsigned int     size,          // IN: size of bytes to read
		    void            *data           // OUT: data buffer
		    )
{
    assert(startOffset + size <= NV_MEMORY_SIZE);
    memcpy(data, &s_NV[startOffset], size);	// Copy data from RAM
    return;
}
/* C.6.2.9. _plat__NvIsDifferent() */
/* This function checks to see if the NV is different from the test value. This is so that NV will
   not be written if it has not changed. */
/* Return Values Meaning */
/* TRUE(1) the NV location is different from the test value */
/* FALSE(0) the NV location is the same as the test value */
LIB_EXPORT int
_plat__NvIsDifferent(
		     unsigned int     startOffset,   // IN: read start
		     unsigned int     size,          // IN: size of bytes to read
		     void            *data           // IN: data buffer
		     )
{
    return (memcmp(&s_NV[startOffset], data, size) != 0);
}
/* C.6.2.10. _plat__NvMemoryWrite() */
/* This function is used to update NV memory. The write is to a memory copy of NV. At the end of the
   current command, any changes are written to the actual NV memory. */
/* NOTE: A useful optimization would be for this code to compare the current contents of NV with the
   local copy and note the blocks that have changed. Then only write those blocks when
   _plat__NvCommit() is called. */

LIB_EXPORT int
_plat__NvMemoryWrite(
		     unsigned int     startOffset,   // IN: write start
		     unsigned int     size,          // IN: size of bytes to write
		     void            *data           // OUT: data buffer
		     )
{
    if(startOffset + size <= NV_MEMORY_SIZE)
	{
	    memcpy(&s_NV[startOffset], data, size);     // Copy the data to the NV image
	    return TRUE;
	}
    return FALSE;
}
/* C.6.2.11. _plat__NvMemoryClear() */
/* Function is used to set a range of NV memory bytes to an implementation-dependent value. The
   value represents the erase state of the memory. */
LIB_EXPORT void
_plat__NvMemoryClear(
		     unsigned int     start,         // IN: clear start
		     unsigned int     size           // IN: number of bytes to clear
		     )
{
    assert(start + size <= NV_MEMORY_SIZE);
    // In this implementation, assume that the erase value for NV is all 1s
    memset(&s_NV[start], 0xff, size);
}
/* C.6.2.12. _plat__NvMemoryMove() */
/* Function: Move a chunk of NV memory from source to destination This function should ensure that
   if there overlap, the original data is copied before it is written */
LIB_EXPORT void
_plat__NvMemoryMove(
		    unsigned int     sourceOffset,  // IN: source offset
		    unsigned int     destOffset,    // IN: destination offset
		    unsigned int     size           // IN: size of data being moved
		    )
{
    assert(sourceOffset + size <= NV_MEMORY_SIZE);
    assert(destOffset + size <= NV_MEMORY_SIZE);
    memmove(&s_NV[destOffset], &s_NV[sourceOffset], size);	// Move data in RAM
    return;
}
/* C.6.2.13. _plat__NvCommit() */
/* This function writes the local copy of NV to NV for permanent store. It will write NV_MEMORY_SIZE
   bytes to NV. If a file is use, the entire file is written. */
/* Return Values Meaning */
/* 0 NV write success */
/* non-0 NV write fail */
LIB_EXPORT int
_plat__NvCommit(
		void
		)
{
#if FILE_BACKED_NV
    return (NvFileCommit() ? 0 : 1);
#else
    return 0;
#endif
}

/* C.6.2.14. _plat__SetNvAvail() */
/* Set the current NV state to available.  This function is for testing purpose only.  It is not
   part of the platform NV logic */
LIB_EXPORT void
_plat__SetNvAvail(
		  void
		  )
{
    s_NvIsAvailable = TRUE;
    return;
}
/* C.6.2.15. _plat__ClearNvAvail() */
/* Set the current NV state to unavailable.  This function is for testing purpose only.  It is not
   part of the platform NV logic */
LIB_EXPORT void
_plat__ClearNvAvail(
		    void
		    )
{
    s_NvIsAvailable = FALSE;
    return;
}

/* C.6.2.15.	_plat__NVNeedsManufacture() */
/* This function is used by the simulator to determine when the TPM's NV state needs to be manufactured. */

LIB_EXPORT int
_plat__NVNeedsManufacture(
			  void
			  )
{
#if FILE_BACKED_NV
    return s_NeedsManufacture;
#else
    return FALSE;
#endif
}