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/* $Id: memsafer-generic.cpp $ */
/** @file
* IPRT - Memory Allocate for Sensitive Data, generic heap-based implementation.
*/
/*
* Copyright (C) 2006-2020 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "internal/iprt.h"
#include <iprt/memsafer.h>
#include <iprt/assert.h>
#include <iprt/err.h>
#include <iprt/string.h>
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
/** Allocation size alignment. */
#define RTMEMSAFER_ALIGN 16
/** Padding after the block to avoid small overruns. */
#define RTMEMSAFER_PAD_BEFORE 96
/** Padding after the block to avoid small underruns. */
#define RTMEMSAFER_PAD_AFTER 32
/*********************************************************************************************************************************
* Global Variables *
*********************************************************************************************************************************/
/** XOR scrabler value.
* @todo determine this at runtime */
#if ARCH_BITS == 32
static uintptr_t g_uScramblerXor = UINT32_C(0x867af88d);
#elif ARCH_BITS == 64
static uintptr_t g_uScramblerXor = UINT64_C(0xed95ecc99416d312);
#else
# error "Bad ARCH_BITS value"
#endif
RTDECL(int) RTMemSaferScramble(void *pv, size_t cb)
{
AssertMsg(*(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE) == cb,
("*pvStart=%#zx cb=%#zx\n", *(size_t *)((char *)pv- RTMEMSAFER_PAD_BEFORE), cb));
/* Note! This isn't supposed to be safe, just less obvious. */
uintptr_t *pu = (uintptr_t *)pv;
cb = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
while (cb > 0)
{
*pu ^= g_uScramblerXor;
pu++;
cb -= sizeof(*pu);
}
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTMemSaferScramble);
RTDECL(int) RTMemSaferUnscramble(void *pv, size_t cb)
{
AssertMsg(*(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE) == cb,
("*pvStart=%#zx cb=%#zx\n", *(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE), cb));
/* Note! This isn't supposed to be safe, just less obvious. */
uintptr_t *pu = (uintptr_t *)pv;
cb = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
while (cb > 0)
{
*pu ^= g_uScramblerXor;
pu++;
cb -= sizeof(*pu);
}
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTMemSaferUnscramble);
RTDECL(int) RTMemSaferAllocZExTag(void **ppvNew, size_t cb, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF
{
AssertPtrReturn(ppvNew, VERR_INVALID_PARAMETER);
*ppvNew = NULL;
AssertReturn(cb, VERR_INVALID_PARAMETER);
RT_NOREF_PV(pszTag);
/*
* We support none of the hard requirements passed thru flags.
*/
if (fFlags == 0)
{
/*
* Don't request zeroed memory. We want random heap garbage in the
* padding zones, nothing that makes our allocations easier to find.
*/
size_t cbUser = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
void *pvNew = RTMemAlloc(cbUser + RTMEMSAFER_PAD_BEFORE + RTMEMSAFER_PAD_AFTER);
if (pvNew)
{
#ifdef RT_STRICT /* For checking input in string builds. */
memset(pvNew, 0xad, RTMEMSAFER_PAD_BEFORE);
memset((char *)pvNew + RTMEMSAFER_PAD_BEFORE + cb, 0xda, RTMEMSAFER_PAD_AFTER + (cbUser - cb));
*(size_t *)pvNew = cb;
#endif
void *pvUser = (char *)pvNew + RTMEMSAFER_PAD_BEFORE;
*ppvNew = pvUser;
/* You don't use this API for performance, so we always clean memory. */
RT_BZERO(pvUser, cb);
return VINF_SUCCESS;
}
return VERR_NO_MEMORY;
}
AssertReturn(!(fFlags & ~RTMEMSAFER_F_VALID_MASK), VERR_INVALID_FLAGS);
return VWRN_UNABLE_TO_SATISFY_REQUIREMENTS;
}
RT_EXPORT_SYMBOL(RTMemSaferAllocZExTag);
RTDECL(void) RTMemSaferFree(void *pv, size_t cb) RT_NO_THROW_DEF
{
if (pv)
{
Assert(cb); /* does not support openssl. */
void *pvStart = (char *)pv - RTMEMSAFER_PAD_BEFORE;
AssertMsg(*(size_t *)pvStart == cb, ("*pvStart=%#zx cb=%#zx\n", *(size_t *)pvStart, cb));
RTMemWipeThoroughly(pv, RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN), 3);
RTMemFree(pvStart);
}
else
Assert(cb == 0);
}
RT_EXPORT_SYMBOL(RTMemSaferFree);
RTDECL(int) RTMemSaferReallocZExTag(size_t cbOld, void *pvOld, size_t cbNew, void **ppvNew, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF
{
/*
* We cannot let the heap move us around because we will be failing in our
* duty to clean things up. So, allocate a new block, copy over the old
* content, and free the old one.
*/
int rc;
/* Real realloc. */
if (cbNew && cbOld)
{
AssertPtr(pvOld);
AssertMsg(*(size_t *)((char *)pvOld - RTMEMSAFER_PAD_BEFORE) == cbOld,
("*pvStart=%#zx cbOld=%#zx\n", *(size_t *)((char *)pvOld - RTMEMSAFER_PAD_BEFORE), cbOld));
/*
* We support none of the hard requirements passed thru flags.
*/
void *pvNew;
rc = RTMemSaferAllocZExTag(&pvNew, cbNew, fFlags, pszTag);
if (RT_SUCCESS(rc))
{
memcpy(pvNew, pvOld, RT_MIN(cbNew, cbOld));
RTMemSaferFree(pvOld, cbOld);
*ppvNew = pvNew;
}
}
/* First allocation. */
else if (!cbOld)
{
Assert(pvOld == NULL);
rc = RTMemSaferAllocZExTag(ppvNew, cbNew, fFlags, pszTag);
}
/* Free operation*/
else
{
RTMemSaferFree(pvOld, cbOld);
rc = VINF_SUCCESS;
}
return rc;
}
RT_EXPORT_SYMBOL(RTMemSaferReallocZExTag);
RTDECL(void *) RTMemSaferAllocZTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
{
void *pvNew = NULL;
int rc = RTMemSaferAllocZExTag(&pvNew, cb, 0 /*fFlags*/, pszTag);
if (RT_SUCCESS(rc))
return pvNew;
return NULL;
}
RT_EXPORT_SYMBOL(RTMemSaferAllocZTag);
RTDECL(void *) RTMemSaferReallocZTag(size_t cbOld, void *pvOld, size_t cbNew, const char *pszTag) RT_NO_THROW_DEF
{
void *pvNew = NULL;
int rc = RTMemSaferReallocZExTag(cbOld, pvOld, cbNew, &pvNew, 0 /*fFlags*/, pszTag);
if (RT_SUCCESS(rc))
return pvNew;
return NULL;
}
RT_EXPORT_SYMBOL(RTMemSaferReallocZTag);
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