/* $Id: memsafer-generic.cpp 56290 2015-06-09 14:01:31Z vboxsync $ */ /** @file * IPRT - Memory Allocate for Sensitive Data, generic heap-based implementation. */ /* * Copyright (C) 2006-2015 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 #include #include /******************************************************************************* * 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 { AssertPtrReturn(ppvNew, VERR_INVALID_PARAMETER); *ppvNew = NULL; AssertReturn(cb, VERR_INVALID_PARAMETER); /* * 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 { if (pv) { Assert(cb); 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 { /* * 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 { 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 { 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);