| 1 | /* $Id: memsafer-generic.cpp 106061 2024-09-16 14:03:52Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - Memory Allocate for Sensitive Data, generic heap-based implementation.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2006-2024 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * The contents of this file may alternatively be used under the terms
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| 26 | * of the Common Development and Distribution License Version 1.0
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| 27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | * in the VirtualBox distribution, in which case the provisions of the
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| 29 | * CDDL are applicable instead of those of the GPL.
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| 30 | *
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| 31 | * You may elect to license modified versions of this file under the
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| 32 | * terms and conditions of either the GPL or the CDDL or both.
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| 33 | *
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| 34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | */
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| 36 |
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| 37 |
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| 38 | /*********************************************************************************************************************************
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| 39 | * Header Files *
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| 40 | *********************************************************************************************************************************/
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| 41 | #include "internal/iprt.h"
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| 42 | #include <iprt/memsafer.h>
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| 43 |
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| 44 | #include <iprt/assert.h>
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| 45 | #include <iprt/err.h>
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| 46 | #include <iprt/string.h>
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| 47 |
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| 48 |
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| 49 | /*********************************************************************************************************************************
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| 50 | * Defined Constants And Macros *
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| 51 | *********************************************************************************************************************************/
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| 52 | /** Allocation size alignment. */
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| 53 | #define RTMEMSAFER_ALIGN 16
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| 54 | /** Padding after the block to avoid small overruns. */
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| 55 | #define RTMEMSAFER_PAD_BEFORE 96
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| 56 | /** Padding after the block to avoid small underruns. */
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| 57 | #define RTMEMSAFER_PAD_AFTER 32
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| 58 |
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| 59 |
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| 60 | /*********************************************************************************************************************************
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| 61 | * Global Variables *
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| 62 | *********************************************************************************************************************************/
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| 63 | /** XOR scrabler value.
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| 64 | * @todo determine this at runtime */
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| 65 | #if ARCH_BITS == 32
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| 66 | static uintptr_t g_uScramblerXor = UINT32_C(0x867af88d);
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| 67 | #elif ARCH_BITS == 64
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| 68 | static uintptr_t g_uScramblerXor = UINT64_C(0xed95ecc99416d312);
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| 69 | #else
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| 70 | # error "Bad ARCH_BITS value"
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| 71 | #endif
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| 72 |
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| 73 |
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| 74 |
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| 75 | RTDECL(int) RTMemSaferScramble(void *pv, size_t cb)
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| 76 | {
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| 77 |
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| 78 | AssertMsg(*(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE) == cb,
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| 79 | ("*pvStart=%#zx cb=%#zx\n", *(size_t *)((char *)pv- RTMEMSAFER_PAD_BEFORE), cb));
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| 80 |
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| 81 | /* Note! This isn't supposed to be safe, just less obvious. */
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| 82 | uintptr_t *pu = (uintptr_t *)pv;
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| 83 | cb = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
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| 84 | while (cb > 0)
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| 85 | {
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| 86 | *pu ^= g_uScramblerXor;
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| 87 | pu++;
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| 88 | cb -= sizeof(*pu);
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| 89 | }
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| 90 |
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| 91 | return VINF_SUCCESS;
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| 92 | }
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| 93 | RT_EXPORT_SYMBOL(RTMemSaferScramble);
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| 94 |
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| 95 |
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| 96 | RTDECL(int) RTMemSaferUnscramble(void *pv, size_t cb)
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| 97 | {
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| 98 | AssertMsg(*(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE) == cb,
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| 99 | ("*pvStart=%#zx cb=%#zx\n", *(size_t *)((char *)pv - RTMEMSAFER_PAD_BEFORE), cb));
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| 100 |
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| 101 | /* Note! This isn't supposed to be safe, just less obvious. */
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| 102 | uintptr_t *pu = (uintptr_t *)pv;
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| 103 | cb = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
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| 104 | while (cb > 0)
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| 105 | {
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| 106 | *pu ^= g_uScramblerXor;
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| 107 | pu++;
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| 108 | cb -= sizeof(*pu);
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| 109 | }
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| 110 |
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| 111 | return VINF_SUCCESS;
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| 112 | }
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| 113 | RT_EXPORT_SYMBOL(RTMemSaferUnscramble);
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| 114 |
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| 115 |
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| 116 | RTDECL(int) RTMemSaferAllocZExTag(void **ppvNew, size_t cb, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF
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| 117 | {
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| 118 | AssertPtrReturn(ppvNew, VERR_INVALID_PARAMETER);
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| 119 | *ppvNew = NULL;
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| 120 | AssertReturn(cb, VERR_INVALID_PARAMETER);
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| 121 | RT_NOREF_PV(pszTag);
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| 122 |
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| 123 | /*
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| 124 | * We support none of the hard requirements passed thru flags.
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| 125 | */
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| 126 | if (fFlags == 0)
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| 127 | {
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| 128 | /*
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| 129 | * Don't request zeroed memory. We want random heap garbage in the
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| 130 | * padding zones, nothing that makes our allocations easier to find.
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| 131 | */
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| 132 | size_t cbUser = RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN);
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| 133 | void *pvNew = RTMemAlloc(cbUser + RTMEMSAFER_PAD_BEFORE + RTMEMSAFER_PAD_AFTER);
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| 134 | if (pvNew)
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| 135 | {
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| 136 | #ifdef RT_STRICT /* For checking input in string builds. */
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| 137 | memset(pvNew, 0xad, RTMEMSAFER_PAD_BEFORE);
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| 138 | memset((char *)pvNew + RTMEMSAFER_PAD_BEFORE + cb, 0xda, RTMEMSAFER_PAD_AFTER + (cbUser - cb));
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| 139 | *(size_t *)pvNew = cb;
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| 140 | #endif
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| 141 |
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| 142 | void *pvUser = (char *)pvNew + RTMEMSAFER_PAD_BEFORE;
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| 143 | *ppvNew = pvUser;
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| 144 |
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| 145 | /* You don't use this API for performance, so we always clean memory. */
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| 146 | RT_BZERO(pvUser, cb);
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| 147 |
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| 148 | return VINF_SUCCESS;
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| 149 | }
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| 150 | return VERR_NO_MEMORY;
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| 151 | }
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| 152 | AssertReturn(!(fFlags & ~RTMEMSAFER_F_VALID_MASK), VERR_INVALID_FLAGS);
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| 153 | return VWRN_UNABLE_TO_SATISFY_REQUIREMENTS;
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| 154 | }
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| 155 | RT_EXPORT_SYMBOL(RTMemSaferAllocZExTag);
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| 156 |
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| 157 |
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| 158 | RTDECL(void) RTMemSaferFree(void *pv, size_t cb) RT_NO_THROW_DEF
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| 159 | {
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| 160 | if (pv)
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| 161 | {
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| 162 | Assert(cb); /* does not support openssl. */
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| 163 | void *pvStart = (char *)pv - RTMEMSAFER_PAD_BEFORE;
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| 164 | AssertMsg(*(size_t *)pvStart == cb, ("*pvStart=%#zx cb=%#zx\n", *(size_t *)pvStart, cb));
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| 165 | RTMemWipeThoroughly(pv, RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN), 3);
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| 166 | RTMemFree(pvStart);
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| 167 | }
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| 168 | else
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| 169 | Assert(cb == 0);
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| 170 | }
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| 171 | RT_EXPORT_SYMBOL(RTMemSaferFree);
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| 172 |
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| 173 |
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| 174 | RTDECL(int) RTMemSaferReallocZExTag(size_t cbOld, void *pvOld, size_t cbNew, void **ppvNew, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF
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| 175 | {
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| 176 | /*
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| 177 | * We cannot let the heap move us around because we will be failing in our
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| 178 | * duty to clean things up. So, allocate a new block, copy over the old
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| 179 | * content, and free the old one.
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| 180 | */
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| 181 | int rc;
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| 182 | /* Real realloc. */
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| 183 | if (cbNew && cbOld)
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| 184 | {
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| 185 | AssertPtr(pvOld);
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| 186 | AssertMsg(*(size_t *)((char *)pvOld - RTMEMSAFER_PAD_BEFORE) == cbOld,
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| 187 | ("*pvStart=%#zx cbOld=%#zx\n", *(size_t *)((char *)pvOld - RTMEMSAFER_PAD_BEFORE), cbOld));
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| 188 |
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| 189 | /*
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| 190 | * We support none of the hard requirements passed thru flags.
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| 191 | */
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| 192 | void *pvNew;
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| 193 | rc = RTMemSaferAllocZExTag(&pvNew, cbNew, fFlags, pszTag);
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| 194 | if (RT_SUCCESS(rc))
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| 195 | {
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| 196 | memcpy(pvNew, pvOld, RT_MIN(cbNew, cbOld));
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| 197 | RTMemSaferFree(pvOld, cbOld);
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| 198 | *ppvNew = pvNew;
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| 199 | }
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| 200 | }
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| 201 | /* First allocation. */
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| 202 | else if (!cbOld)
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| 203 | {
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| 204 | Assert(pvOld == NULL);
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| 205 | rc = RTMemSaferAllocZExTag(ppvNew, cbNew, fFlags, pszTag);
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| 206 | }
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| 207 | /* Free operation*/
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| 208 | else
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| 209 | {
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| 210 | RTMemSaferFree(pvOld, cbOld);
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| 211 | rc = VINF_SUCCESS;
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| 212 | }
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| 213 | return rc;
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| 214 | }
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| 215 | RT_EXPORT_SYMBOL(RTMemSaferReallocZExTag);
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| 216 |
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| 217 |
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| 218 | RTDECL(void *) RTMemSaferAllocZTag(size_t cb, const char *pszTag) RT_NO_THROW_DEF
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| 219 | {
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| 220 | void *pvNew = NULL;
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| 221 | int rc = RTMemSaferAllocZExTag(&pvNew, cb, 0 /*fFlags*/, pszTag);
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| 222 | if (RT_SUCCESS(rc))
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| 223 | return pvNew;
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| 224 | return NULL;
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| 225 | }
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| 226 | RT_EXPORT_SYMBOL(RTMemSaferAllocZTag);
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| 227 |
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| 228 |
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| 229 | RTDECL(void *) RTMemSaferReallocZTag(size_t cbOld, void *pvOld, size_t cbNew, const char *pszTag) RT_NO_THROW_DEF
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| 230 | {
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| 231 | void *pvNew = NULL;
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| 232 | int rc = RTMemSaferReallocZExTag(cbOld, pvOld, cbNew, &pvNew, 0 /*fFlags*/, pszTag);
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| 233 | if (RT_SUCCESS(rc))
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| 234 | return pvNew;
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| 235 | return NULL;
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| 236 | }
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| 237 | RT_EXPORT_SYMBOL(RTMemSaferReallocZTag);
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| 238 |
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