VeraCrypt/src/Common/Cache.c

/*
 Legal Notice: Some portions of the source code contained in this file were
 derived from the source code of TrueCrypt 7.1a, which is
 Copyright (c) 2003-2012 TrueCrypt Developers Association and which is
 governed by the TrueCrypt License 3.0, also from the source code of
 Encryption for the Masses 2.02a, which is Copyright (c) 1998-2000 Paul Le Roux
 and which is governed by the 'License Agreement for Encryption for the Masses'
 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2017 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages. */

#include "Tcdefs.h"
#include "Crypto.h"
#include "Fat.h"
#include "Volumes.h"
#include "Apidrvr.h"
#include "Common.h"
#include "Cache.h"

Password CachedPasswords[CACHE_SIZE];
int	 CachedPim[CACHE_SIZE];
int cacheEmpty = 1;
static int nPasswordIdx = 0;

#ifdef _WIN64

uint64 VcGetPasswordEncryptionID (Password* pPassword)
{
	return ((uint64) pPassword->Text) + ((uint64) pPassword);
}

void VcProtectPassword (Password* pPassword, uint64 encID)
{
	VcProtectMemory (encID, (unsigned char*) pPassword->Text, sizeof(pPassword->Text), (unsigned char*) &pPassword->Length, sizeof (pPassword->Length));
}

void VcUnprotectPassword (Password* pPassword, uint64 encID)
{
	VcProtectPassword (pPassword, encID);
}

#endif

int ReadVolumeHeaderWCache (BOOL bBoot, BOOL bCache, BOOL bCachePim, char *header, Password *password, int pkcs5_prf, int pim, PCRYPTO_INFO *retInfo)
{
	int nReturnCode = ERR_PASSWORD_WRONG;
	int i, effectivePim;

	/* Attempt to recognize volume using mount password */
	if (password->Length > 0)
	{
		nReturnCode = ReadVolumeHeader (bBoot, header, password, pkcs5_prf, pim, retInfo, NULL);

		/* Save mount passwords back into cache if asked to do so */
		if (bCache && (nReturnCode == 0 || nReturnCode == ERR_CIPHER_INIT_WEAK_KEY))
		{
#ifdef _WIN64
			Password tmpPass;
#endif
			for (i = 0; i < CACHE_SIZE; i++)
			{
				Password* pCurrentPassword = &CachedPasswords[i];
#ifdef _WIN64
				if (IsRamEncryptionEnabled())
				{
					memcpy (&tmpPass, pCurrentPassword, sizeof (Password));
					VcUnprotectPassword (&tmpPass, VcGetPasswordEncryptionID (pCurrentPassword));
					pCurrentPassword = &tmpPass;
				}
#endif
				if (memcmp (pCurrentPassword, password, sizeof (Password)) == 0)
					break;
			}

#ifdef _WIN64
			if (IsRamEncryptionEnabled())
				burn (&tmpPass, sizeof (Password));
#endif

			if (i == CACHE_SIZE)
			{
				/* Store the password */
				CachedPasswords[nPasswordIdx] = *password;
#ifdef _WIN64
				if (IsRamEncryptionEnabled ())
					VcProtectPassword (&CachedPasswords[nPasswordIdx], VcGetPasswordEncryptionID (&CachedPasswords[nPasswordIdx]));
#endif

				/* Store also PIM if requested, otherwise set to default */
				if (bCachePim && (pim > 0))
					CachedPim[nPasswordIdx] = pim;
				else
					CachedPim[nPasswordIdx] = 0;

				/* Try another slot */
				nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE;

				cacheEmpty = 0;
			}
			else if (bCachePim)
			{
				CachedPim[i] = pim > 0? pim : 0;
			}
		}
	}
	else if (!cacheEmpty)
	{
#ifdef _WIN64
		Password tmpPass;
#endif
		/* Attempt to recognize volume using cached passwords */
		for (i = 0; i < CACHE_SIZE; i++)
		{
			Password* pCurrentPassword = &CachedPasswords[i];
#ifdef _WIN64
			if (IsRamEncryptionEnabled())
			{
				memcpy (&tmpPass, pCurrentPassword, sizeof (Password));
				VcUnprotectPassword (&tmpPass, VcGetPasswordEncryptionID (pCurrentPassword));
				pCurrentPassword = &tmpPass;
			}
#endif
			if ((pCurrentPassword->Length > 0) && (pCurrentPassword->Length <= (unsigned int) ((bBoot? MAX_LEGACY_PASSWORD: MAX_PASSWORD))))
			{
				if (pim == -1)
					effectivePim = CachedPim[i];
				else
					effectivePim = pim;
				nReturnCode = ReadVolumeHeader (bBoot, header, pCurrentPassword, pkcs5_prf, effectivePim, retInfo, NULL);

				if (nReturnCode != ERR_PASSWORD_WRONG)
					break;
			}
		}
#ifdef _WIN64
		if (IsRamEncryptionEnabled())
			burn (&tmpPass, sizeof (Password));
#endif
	}

	return nReturnCode;
}


void AddPasswordToCache (Password *password, int pim, BOOL bCachePim)
{
#ifdef _WIN64
	Password tmpPass;
#endif
	int i;
	for (i = 0; i < CACHE_SIZE; i++)
	{
		Password* pCurrentPassword = &CachedPasswords[i];
#ifdef _WIN64
		if (IsRamEncryptionEnabled())
		{
			memcpy (&tmpPass, pCurrentPassword, sizeof (Password));
			VcUnprotectPassword (&tmpPass, VcGetPasswordEncryptionID (pCurrentPassword));
			pCurrentPassword = &tmpPass;
		}
#endif
		if (memcmp (pCurrentPassword, password, sizeof (Password)) == 0)
			break;
	}

	if (i == CACHE_SIZE)
	{
		CachedPasswords[nPasswordIdx] = *password;
#ifdef _WIN64
		if (IsRamEncryptionEnabled ())
			VcProtectPassword (&CachedPasswords[nPasswordIdx], VcGetPasswordEncryptionID (&CachedPasswords[nPasswordIdx]));
#endif
		/* Store also PIM if requested, otherwise set to default */
		if (bCachePim && (pim > 0))
			CachedPim[nPasswordIdx] = pim;
		else
			CachedPim[nPasswordIdx] = 0;
		nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE;
		cacheEmpty = 0;
	}
	else if (bCachePim)
	{
		CachedPim[i] = pim > 0? pim : 0;
	}
#ifdef _WIN64
	if (IsRamEncryptionEnabled())
		burn (&tmpPass, sizeof (Password));
#endif
}

void AddLegacyPasswordToCache (PasswordLegacy *password, int pim)
{
	Password inputPass = {0};
	inputPass.Length = password->Length;
	memcpy (inputPass.Text, password->Text, password->Length);

	AddPasswordToCache (&inputPass, pim, TRUE);

	burn (&inputPass, sizeof (inputPass));
}

void WipeCache ()
{
	burn (CachedPasswords, sizeof (CachedPasswords));
	burn (CachedPim, sizeof (CachedPim));
	nPasswordIdx = 0;
	cacheEmpty = 1;
}