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/** @file
* IPRT - Memory Allocate for Sensitive Data.
*/
/*
* Copyright (C) 2006-2022 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox 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.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#ifndef IPRT_INCLUDED_memsafer_h
#define IPRT_INCLUDED_memsafer_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
#include <iprt/mem.h> /* RTMEM_TAG */
RT_C_DECLS_BEGIN
/** @defgroup grp_rt_memsafer RTMemSafer - Memory Allocator for Sensitive Data
* @ingroup grp_rt
*
* This API doesn't provide 100% secure storage, it only provider more secure
* and safer storage. Thus the API isn't called RTMemSafe because you cannot
* assume the data is safe against all kinds of extraction methods.
*
* The API guarantee that the memory won't be returned to the system containing
* any of the information you put there. It will be repeatedly wiped after use.
*
* The API tries to isolate your data from other information stored in the
* process/system. How well this is done depends on the implementation. The
* more complicated implementations will provide protection against heartbleed
* like bugs where pieces of the heap is copied onto the wire.
*
* The more hardened implementations of the API will also do their best to
* prevent the memory from ending up in process dumps or being readable by
* debuggers.
*
* Finally, two functions are provided for scrambling the sensitive memory while
* it's not in use.
*
* @{
*/
/** @name RTMEMSAFER_F_XXX
* @{ */
/** Require the memory to not hit the page file.
* @remarks Makes not guarantees with regards to hibernation /
* suspend-to-disk. */
#define RTMEMSAFER_F_REQUIRE_NOT_PAGABLE RT_BIT_32(0)
/** Mask of valid bits. */
#define RTMEMSAFER_F_VALID_MASK UINT32_C(0x00000001)
/** @} */
/**
* Scrambles memory allocated by RTMemSaferAllocZEx and associates after use.
*
* Call this when the sensitive data isn't actively being used. It will at a
* minimum make sure the data is slightly scrambled, how hard it is to unbutton
* is dependent on which implementation is used and available host support.
*
* The user must synchronize calls to RTMemSaferScramble and
* RTMemSaferUnscramble, this memory allocator provides no help and keeps no
* state information around.
*
* @returns IPRT status code.
* @param pv The pointer returned by the allocation function.
* @param cb The exact size given to the allocation function.
*/
RTDECL(int) RTMemSaferScramble(void *pv, size_t cb);
/**
* Unscrambles memory allocated by RTMemSaferAllocZEx and associates before use.
*
* This undoes the effect of RTMemSaferScramble.
*
* @returns IPRT status code.
* @param pv The pointer returned by the allocation function.
* @param cb The exact size given to the allocation function.
*/
RTDECL(int) RTMemSaferUnscramble(void *pv, size_t cb);
/**
* Allocates memory for sensitive data.
*
* Some effort will be taken to isolate the data from other memory allocation.
* Memory is always zeroed.
*
* @returns IPRT status code.
* @param ppvNew Where to return the pointer to the memory.
* @param cb Number of bytes to allocate.
* @param fFlags Flags for controlling the allocation, see
* RTMEMSAFER_F_XXX.
* @param pszTag Allocation tag used for statistics and such.
*/
RTDECL(int) RTMemSaferAllocZExTag(void **ppvNew, size_t cb, uint32_t fFlags, const char *pszTag) RT_NO_THROW_PROTO;
/**
* Allocates memory for sensitive data.
*
* Some effort will be taken to isolate the data from other memory allocation.
* Memory is always zeroed.
*
* @returns IPRT status code.
* @param a_ppvNew Where to return the pointer to the memory.
* @param a_cb Number of bytes to allocate.
* @param a_fFlags Flags for controlling the allocation, see
* RTMEMSAFER_F_XXX.
*/
#define RTMemSaferAllocZEx(a_ppvNew, a_cb, a_fFlags) RTMemSaferAllocZExTag(a_ppvNew, a_cb, a_fFlags, RTMEM_TAG)
/**
* Allocates memory for sensitive data.
*
* Some effort will be taken to isolate the data from other memory allocation.
* Memory is always zeroed.
*
* @returns Pointer to the allocated memory.
* @param cb Number of bytes to allocate.
* @param pszTag Allocation tag used for statistics and such.
*/
RTDECL(void *) RTMemSaferAllocZTag(size_t cb, const char *pszTag) RT_NO_THROW_PROTO;
/**
* Allocates memory for sensitive data.
*
* Some effort will be taken to isolate the data from other memory allocation.
* Memory is always zeroed.
*
* @returns Pointer to the allocated memory.
* @param a_cb Number of bytes to allocate.
*/
#define RTMemSaferAllocZ(a_cb) RTMemSaferAllocZTag(a_cb, RTMEM_TAG)
/**
* Reallocates memory allocated by RTMemSaferAllocZEx, RTMemSaferAllocZ,
* RTMemSaferAllocZExTag, or RTMemSaferAllocZTag.
*
* When extending the allocation, the new memory will be zeroed. When shrinking
* the allocation the left over memory will be wiped clean using
* RTMemWipeThorougly.
*
* The function follows the standard realloc behavior.
*
* @returns IPRT status code.
* @param cbOld The current allocation size.
* @param pvOld The current allocation.
* @param cbNew The size of the new allocation.
* @param ppvNew Where to return the pointer to the new memory.
* @param fFlags Flags for controlling the allocation, see
* RTMEMSAFER_F_XXX. It is not permitted to drop saftely
* requirments after the initial allocation.
* @param pszTag Allocation tag used for statistics and such.
*/
RTDECL(int) RTMemSaferReallocZExTag(size_t cbOld, void *pvOld, size_t cbNew, void **ppvNew, uint32_t fFlags, const char *pszTag) RT_NO_THROW_PROTO;
/**
* Reallocates memory allocated by RTMemSaferAllocZEx, RTMemSaferAllocZ,
* RTMemSaferAllocZExTag, or RTMemSaferAllocZTag.
*
* When extending the allocation, the new memory will be zeroed. When shrinking
* the allocation the left over memory will be wiped clean using
* RTMemWipeThorougly.
*
* The function follows the standard realloc behavior.
*
* @returns IPRT status code.
* @param a_cbOld The current allocation size.
* @param a_pvOld The current allocation.
* @param a_cbNew The size of the new allocation.
* @param a_ppvNew Where to return the pointer to the new memory.
* @param a_fFlags Flags for controlling the allocation. See RTMEMSAFER_ALLOC_EX_FLAGS_* defines,
* this takes only effect when allocating completely new memory, for extending or
* shrinking existing allocations the flags of the allocation take precedence.
*/
#define RTMemSaferReallocZEx(a_cbOld, a_pvOld, a_cbNew, a_ppvNew, a_fFlags) \
RTMemSaferReallocZExTag(a_cbOld, a_pvOld, a_cbNew, a_ppvNew, a_fFlags, RTMEM_TAG)
/**
* Reallocates memory allocated by RTMemSaferAllocZ or RTMemSaferAllocZTag.
*
* When extending the allocation, the new memory will be zeroed. When shrinking
* the allocation the left over memory will be wiped clean using
* RTMemWipeThorougly.
*
* The function follows the standard realloc behavior.
*
* @returns Pointer to the allocated memory.
* @param cbOld The current allocation size.
* @param pvOld The current allocation.
* @param cbNew The size of the new allocation.
* @param pszTag Allocation tag used for statistics and such.
*/
RTDECL(void *) RTMemSaferReallocZTag(size_t cbOld, void *pvOld, size_t cbNew, const char *pszTag) RT_NO_THROW_PROTO;
/**
* Reallocates memory allocated by RTMemSaferAllocZ or RTMemSaferAllocZTag.
*
* When extending the allocation, the new memory will be zeroed. When shrinking
* the allocation the left over memory will be wiped clean using
* RTMemWipeThorougly.
*
* The function follows the standard realloc behavior.
*
* @returns Pointer to the allocated memory.
* @param a_cbOld The current allocation size.
* @param a_pvOld The current allocation.
* @param a_cbNew The size of the new allocation.
*/
#define RTMemSaferReallocZ(a_cbOld, a_pvOld, a_cbNew) RTMemSaferReallocZTag(a_cbOld, a_pvOld, a_cbNew, RTMEM_TAG)
/**
* Frees memory allocated by RTMemSaferAllocZ* or RTMemSaferReallocZ*.
*
* Before freeing the allocated memory, it will be wiped clean using
* RTMemWipeThorougly.
*
* @returns Pointer to the allocated memory.
* @param pv The allocation.
* @param cb The allocation size.
*/
RTDECL(void) RTMemSaferFree(void *pv, size_t cb) RT_NO_THROW_PROTO;
/**
* Gets the amount of memory allocated at @a pv.
*
* This can be used to check if the allocation was made using an RTMemSafer API.
*
* @returns Allocation size in bytes, 0 if not a RTMemSafer allocation.
* @param pv The alleged RTMemSafer allocation.
*
* @note Not supported in all contexts and implementations of the API.
*/
RTDECL(size_t) RTMemSaferGetSize(void *pv) RT_NO_THROW_PROTO;
/** @} */
RT_C_DECLS_END
#endif /* !IPRT_INCLUDED_memsafer_h */
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