/* $Id: memsafer-r3.cpp 76417 2018-12-23 18:59:47Z vboxsync $ */ /** @file * IPRT - Memory Allocate for Sensitive Data, generic heap-based implementation. */ /* * Copyright (C) 2006-2017 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 #include #include #include #include #include #include #include #include #ifdef IN_SUP_R3 # include #endif /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ /** Allocation size alignment (power of two). */ #define RTMEMSAFER_ALIGN 16 /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** * Allocators. */ typedef enum RTMEMSAFERALLOCATOR { /** Invalid method. */ RTMEMSAFERALLOCATOR_INVALID = 0, /** RTMemPageAlloc. */ RTMEMSAFERALLOCATOR_RTMEMPAGE, /** SUPR3PageAllocEx. */ RTMEMSAFERALLOCATOR_SUPR3 } RTMEMSAFERALLOCATOR; /** * Tracking node (lives on normal heap). */ typedef struct RTMEMSAFERNODE { /** Node core. * The core key is a scrambled pointer the user memory. */ AVLPVNODECORE Core; /** The allocation flags. */ uint32_t fFlags; /** The offset into the allocation of the user memory. */ uint32_t offUser; /** The requested allocation size. */ size_t cbUser; /** The allocation size in pages, this includes the two guard pages. */ uint32_t cPages; /** The allocator used for this node. */ RTMEMSAFERALLOCATOR enmAllocator; /** XOR scrambler value for memory. */ uintptr_t uScramblerXor; } RTMEMSAFERNODE; /** Pointer to an allocation tracking node. */ typedef RTMEMSAFERNODE *PRTMEMSAFERNODE; /********************************************************************************************************************************* * Global Variables * *********************************************************************************************************************************/ /** Init once structure for this module. */ static RTONCE g_MemSaferOnce = RTONCE_INITIALIZER; /** Critical section protecting the allocation tree. */ static RTCRITSECTRW g_MemSaferCritSect; /** Tree of allocation nodes. */ static AVLPVTREE g_pMemSaferTree; /** XOR scrambler value pointers. */ static uintptr_t g_uMemSaferPtrScramblerXor; /** Pointer rotate shift count.*/ static uintptr_t g_cMemSaferPtrScramblerRotate; /** * @callback_method_impl{FNRTONCE, Inits globals.} */ static DECLCALLBACK(int32_t) rtMemSaferOnceInit(void *pvUserIgnore) { RT_NOREF_PV(pvUserIgnore); g_uMemSaferPtrScramblerXor = (uintptr_t)RTRandU64(); g_cMemSaferPtrScramblerRotate = RTRandU32Ex(0, ARCH_BITS - 1); return RTCritSectRwInit(&g_MemSaferCritSect); } /** * @callback_method_impl{PFNRTONCECLEANUP, Cleans up globals.} */ static DECLCALLBACK(void) rtMemSaferOnceTerm(void *pvUser, bool fLazyCleanUpOk) { RT_NOREF_PV(pvUser); if (!fLazyCleanUpOk) { RTCritSectRwDelete(&g_MemSaferCritSect); Assert(!g_pMemSaferTree); } } DECLINLINE(void *) rtMemSaferScramblePointer(void *pvUser) { uintptr_t uPtr = (uintptr_t)pvUser; uPtr ^= g_uMemSaferPtrScramblerXor; #if ARCH_BITS == 64 uPtr = ASMRotateRightU64(uPtr, g_cMemSaferPtrScramblerRotate); #elif ARCH_BITS == 32 uPtr = ASMRotateRightU32(uPtr, g_cMemSaferPtrScramblerRotate); #else # error "Unsupported/missing ARCH_BITS." #endif return (void *)uPtr; } /** * Inserts a tracking node into the tree. * * @param pThis The allocation tracking node to insert. */ static void rtMemSaferNodeInsert(PRTMEMSAFERNODE pThis) { RTCritSectRwEnterExcl(&g_MemSaferCritSect); pThis->Core.Key = rtMemSaferScramblePointer(pThis->Core.Key); bool fRc = RTAvlPVInsert(&g_pMemSaferTree, &pThis->Core); RTCritSectRwLeaveExcl(&g_MemSaferCritSect); Assert(fRc); NOREF(fRc); } /** * Finds a tracking node into the tree. * * @returns The allocation tracking node for @a pvUser. NULL if not found. * @param pvUser The user pointer to the allocation. */ static PRTMEMSAFERNODE rtMemSaferNodeLookup(void *pvUser) { void *pvKey = rtMemSaferScramblePointer(pvUser); RTCritSectRwEnterShared(&g_MemSaferCritSect); PRTMEMSAFERNODE pThis = (PRTMEMSAFERNODE)RTAvlPVGet(&g_pMemSaferTree, pvKey); RTCritSectRwLeaveShared(&g_MemSaferCritSect); return pThis; } /** * Removes a tracking node from the tree. * * @returns The allocation tracking node for @a pvUser. NULL if not found. * @param pvUser The user pointer to the allocation. */ static PRTMEMSAFERNODE rtMemSaferNodeRemove(void *pvUser) { void *pvKey = rtMemSaferScramblePointer(pvUser); RTCritSectRwEnterExcl(&g_MemSaferCritSect); PRTMEMSAFERNODE pThis = (PRTMEMSAFERNODE)RTAvlPVRemove(&g_pMemSaferTree, pvKey); RTCritSectRwLeaveExcl(&g_MemSaferCritSect); return pThis; } RTDECL(int) RTMemSaferScramble(void *pv, size_t cb) { PRTMEMSAFERNODE pThis = rtMemSaferNodeLookup(pv); AssertReturn(pThis, VERR_INVALID_POINTER); AssertMsgReturn(cb == pThis->cbUser, ("cb=%#zx != %#zx\n", cb, pThis->cbUser), VERR_INVALID_PARAMETER); /* First time we get a new xor value. */ if (!pThis->uScramblerXor) pThis->uScramblerXor = (uintptr_t)RTRandU64(); /* 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 ^= pThis->uScramblerXor; pu++; cb -= sizeof(*pu); } return VINF_SUCCESS; } RT_EXPORT_SYMBOL(RTMemSaferScramble); RTDECL(int) RTMemSaferUnscramble(void *pv, size_t cb) { PRTMEMSAFERNODE pThis = rtMemSaferNodeLookup(pv); AssertReturn(pThis, VERR_INVALID_POINTER); AssertMsgReturn(cb == pThis->cbUser, ("cb=%#zx != %#zx\n", cb, pThis->cbUser), VERR_INVALID_PARAMETER); /* 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 ^= pThis->uScramblerXor; pu++; cb -= sizeof(*pu); } return VINF_SUCCESS; } RT_EXPORT_SYMBOL(RTMemSaferUnscramble); /** * Initializes the pages. * * Fills the memory with random bytes in order to make it less obvious where the * secret data starts and ends. We also zero the user memory in case the * allocator does not do this. * * @param pThis The allocation tracer node. The Core.Key member * will be set. * @param pvPages The pages to initialize. */ static void rtMemSaferInitializePages(PRTMEMSAFERNODE pThis, void *pvPages) { RTRandBytes(pvPages, PAGE_SIZE + pThis->offUser); uint8_t *pbUser = (uint8_t *)pvPages + PAGE_SIZE + pThis->offUser; pThis->Core.Key = pbUser; RT_BZERO(pbUser, pThis->cbUser); /* paranoia */ RTRandBytes(pbUser + pThis->cbUser, (size_t)pThis->cPages * PAGE_SIZE - PAGE_SIZE - pThis->offUser - pThis->cbUser); } /** * Allocates and initializes pages from the support driver and initializes it. * * @returns VBox status code. * @param pThis The allocator node. Core.Key will be set on successful * return (unscrambled). */ static int rtMemSaferSupR3AllocPages(PRTMEMSAFERNODE pThis) { #ifdef IN_SUP_R3 /* * Try allocate the memory. */ void *pvPages; int rc = SUPR3PageAllocEx(pThis->cPages, 0 /* fFlags */, &pvPages, NULL /* pR0Ptr */, NULL /* paPages */); if (RT_SUCCESS(rc)) { rtMemSaferInitializePages(pThis, pvPages); /* * On darwin we cannot allocate pages without an R0 mapping and * SUPR3PageAllocEx falls back to another method which is incompatible with * the way SUPR3PageProtect works. Ignore changing the protection of the guard * pages. */ #ifdef RT_OS_DARWIN return VINF_SUCCESS; #else /* * Configure the guard pages. * SUPR3PageProtect isn't supported on all hosts, we ignore that. */ rc = SUPR3PageProtect(pvPages, NIL_RTR0PTR, 0, PAGE_SIZE, RTMEM_PROT_NONE); if (RT_SUCCESS(rc)) { rc = SUPR3PageProtect(pvPages, NIL_RTR0PTR, (pThis->cPages - 1) * PAGE_SIZE, PAGE_SIZE, RTMEM_PROT_NONE); if (RT_SUCCESS(rc)) return VINF_SUCCESS; SUPR3PageProtect(pvPages, NIL_RTR0PTR, 0, PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); } else if (rc == VERR_NOT_SUPPORTED) return VINF_SUCCESS; /* failed. */ int rc2 = SUPR3PageFreeEx(pvPages, pThis->cPages); AssertRC(rc2); #endif } return rc; #else /* !IN_SUP_R3 */ RT_NOREF_PV(pThis); return VERR_NOT_SUPPORTED; #endif /* !IN_SUP_R3 */ } /** * Allocates and initializes pages using the IPRT page allocator API. * * @returns VBox status code. * @param pThis The allocator node. Core.Key will be set on successful * return (unscrambled). */ static int rtMemSaferMemAllocPages(PRTMEMSAFERNODE pThis) { /* * Try allocate the memory. */ int rc = VINF_SUCCESS; void *pvPages = RTMemPageAlloc((size_t)pThis->cPages * PAGE_SIZE); if (pvPages) { rtMemSaferInitializePages(pThis, pvPages); /* * Configure the guard pages. */ rc = RTMemProtect(pvPages, PAGE_SIZE, RTMEM_PROT_NONE); if (RT_SUCCESS(rc)) { rc = RTMemProtect((uint8_t *)pvPages + (size_t)(pThis->cPages - 1U) * PAGE_SIZE, PAGE_SIZE, RTMEM_PROT_NONE); if (RT_SUCCESS(rc)) return VINF_SUCCESS; rc = RTMemProtect(pvPages, PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); } /* failed. */ RTMemPageFree(pvPages, (size_t)pThis->cPages * PAGE_SIZE); } else rc = VERR_NO_PAGE_MEMORY; return rc; } RTDECL(int) RTMemSaferAllocZExTag(void **ppvNew, size_t cb, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF { RT_NOREF_PV(pszTag); /* * Validate input. */ AssertPtrReturn(ppvNew, VERR_INVALID_PARAMETER); *ppvNew = NULL; AssertReturn(cb, VERR_INVALID_PARAMETER); AssertReturn(cb <= 32U*_1M - PAGE_SIZE * 3U, VERR_ALLOCATION_TOO_BIG); /* Max 32 MB minus padding and guard pages. */ AssertReturn(!(fFlags & ~RTMEMSAFER_F_VALID_MASK), VERR_INVALID_FLAGS); /* * Initialize globals. */ int rc = RTOnceEx(&g_MemSaferOnce, rtMemSaferOnceInit, rtMemSaferOnceTerm, NULL); if (RT_SUCCESS(rc)) { /* * Allocate a tracker node first. */ PRTMEMSAFERNODE pThis = (PRTMEMSAFERNODE)RTMemAllocZ(sizeof(RTMEMSAFERNODE)); if (pThis) { /* * Prepare the allocation. */ pThis->cbUser = cb; pThis->offUser = (RTRandU32Ex(0, 128) * RTMEMSAFER_ALIGN) & PAGE_OFFSET_MASK; size_t cbNeeded = pThis->offUser + pThis->cbUser; cbNeeded = RT_ALIGN_Z(cbNeeded, PAGE_SIZE); pThis->cPages = (uint32_t)(cbNeeded / PAGE_SIZE) + 2; /* +2 for guard pages */ /* * Try allocate the memory, using the best allocator by default and * falling back on the less safe one. */ rc = rtMemSaferSupR3AllocPages(pThis); if (RT_SUCCESS(rc)) pThis->enmAllocator = RTMEMSAFERALLOCATOR_SUPR3; else if (!(fFlags & RTMEMSAFER_F_REQUIRE_NOT_PAGABLE)) { rc = rtMemSaferMemAllocPages(pThis); if (RT_SUCCESS(rc)) pThis->enmAllocator = RTMEMSAFERALLOCATOR_RTMEMPAGE; } if (RT_SUCCESS(rc)) { /* * Insert the node. */ *ppvNew = pThis->Core.Key; rtMemSaferNodeInsert(pThis); /* (Scrambles Core.Key) */ return VINF_SUCCESS; } RTMemFree(pThis); } else rc = VERR_NO_MEMORY; } return rc; } RT_EXPORT_SYMBOL(RTMemSaferAllocZExTag); RTDECL(void) RTMemSaferFree(void *pv, size_t cb) RT_NO_THROW_DEF { if (pv) { PRTMEMSAFERNODE pThis = rtMemSaferNodeRemove(pv); AssertReturnVoid(pThis); AssertMsg(cb == pThis->cbUser, ("cb=%#zx != %#zx\n", cb, pThis->cbUser)); /* * Wipe the user memory first. */ RTMemWipeThoroughly(pv, RT_ALIGN_Z(cb, RTMEMSAFER_ALIGN), 3); /* * Free the pages. */ uint8_t *pbPages = (uint8_t *)pv - pThis->offUser - PAGE_SIZE; size_t cbPages = (size_t)pThis->cPages * PAGE_SIZE; switch (pThis->enmAllocator) { #ifdef IN_SUP_R3 case RTMEMSAFERALLOCATOR_SUPR3: SUPR3PageProtect(pbPages, NIL_RTR0PTR, 0, PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); SUPR3PageProtect(pbPages, NIL_RTR0PTR, (uint32_t)(cbPages - PAGE_SIZE), PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); SUPR3PageFreeEx(pbPages, pThis->cPages); break; #endif case RTMEMSAFERALLOCATOR_RTMEMPAGE: RTMemProtect(pbPages, PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); RTMemProtect(pbPages + cbPages - PAGE_SIZE, PAGE_SIZE, RTMEM_PROT_READ | RTMEM_PROT_WRITE); RTMemPageFree(pbPages, cbPages); break; default: AssertFailed(); } /* * Free the tracking node. */ pThis->Core.Key = NULL; pThis->offUser = 0; pThis->cbUser = 0; RTMemFree(pThis); } else Assert(cb == 0); } RT_EXPORT_SYMBOL(RTMemSaferFree); /** * The simplest reallocation method: allocate new block, copy over the data, * free old block. */ static int rtMemSaferReallocSimpler(size_t cbOld, void *pvOld, size_t cbNew, void **ppvNew, uint32_t fFlags, const char *pszTag) { void *pvNew; int rc = RTMemSaferAllocZExTag(&pvNew, cbNew, fFlags, pszTag); if (RT_SUCCESS(rc)) { memcpy(pvNew, pvOld, RT_MIN(cbNew, cbOld)); RTMemSaferFree(pvOld, cbOld); *ppvNew = pvNew; } return rc; } RTDECL(int) RTMemSaferReallocZExTag(size_t cbOld, void *pvOld, size_t cbNew, void **ppvNew, uint32_t fFlags, const char *pszTag) RT_NO_THROW_DEF { int rc; /* Real realloc. */ if (cbNew && cbOld) { PRTMEMSAFERNODE pThis = rtMemSaferNodeLookup(pvOld); AssertReturn(pThis, VERR_INVALID_POINTER); AssertMsgStmt(cbOld == pThis->cbUser, ("cbOld=%#zx != %#zx\n", cbOld, pThis->cbUser), cbOld = pThis->cbUser); if (pThis->fFlags == fFlags) { if (cbNew > cbOld) { /* * Is the enough room for us to grow? */ size_t cbMax = (size_t)(pThis->cPages - 2) * PAGE_SIZE; if (cbNew <= cbMax) { size_t const cbAdded = (cbNew - cbOld); size_t const cbAfter = cbMax - pThis->offUser - cbOld; if (cbAfter >= cbAdded) { /* * Sufficient space after the current allocation. */ uint8_t *pbNewSpace = (uint8_t *)pvOld + cbOld; RT_BZERO(pbNewSpace, cbAdded); *ppvNew = pvOld; } else { /* * Have to move the allocation to make enough room at the * end. In order to make it a little less predictable and * maybe avoid a relocation or two in the next call, divide * the page offset by four until it it fits. */ AssertReturn(rtMemSaferNodeRemove(pvOld) == pThis, VERR_INTERNAL_ERROR_3); uint32_t offNewUser = pThis->offUser; do offNewUser = offNewUser / 2; while ((pThis->offUser - offNewUser) + cbAfter < cbAdded); offNewUser &= ~(RTMEMSAFER_ALIGN - 1U); uint32_t const cbMove = pThis->offUser - offNewUser; uint8_t *pbNew = (uint8_t *)pvOld - cbMove; memmove(pbNew, pvOld, cbOld); RT_BZERO(pbNew + cbOld, cbAdded); if (cbMove > cbAdded) RTMemWipeThoroughly(pbNew + cbNew, cbMove - cbAdded, 3); pThis->offUser = offNewUser; pThis->Core.Key = pbNew; *ppvNew = pbNew; rtMemSaferNodeInsert(pThis); } Assert(((uintptr_t)*ppvNew & PAGE_OFFSET_MASK) == pThis->offUser); pThis->cbUser = cbNew; rc = VINF_SUCCESS; } else { /* * Not enough space, allocate a new block and copy over the data. */ rc = rtMemSaferReallocSimpler(cbOld, pvOld, cbNew, ppvNew, fFlags, pszTag); } } else { /* * Shrinking the allocation, just wipe the memory that is no longer * being used. */ if (cbNew != cbOld) { uint8_t *pbAbandond = (uint8_t *)pvOld + cbNew; RTMemWipeThoroughly(pbAbandond, cbOld - cbNew, 3); } pThis->cbUser = cbNew; *ppvNew = pvOld; rc = VINF_SUCCESS; } } else if (!pThis->fFlags) { /* * New flags added. Allocate a new block and copy over the old one. */ rc = rtMemSaferReallocSimpler(cbOld, pvOld, cbNew, ppvNew, fFlags, pszTag); } else { /* Compatible flags. */ AssertMsgFailed(("fFlags=%#x old=%#x\n", fFlags, pThis->fFlags)); rc = VERR_INVALID_FLAGS; } } /* * First allocation. Pass it on. */ else if (!cbOld) { Assert(pvOld == NULL); rc = RTMemSaferAllocZExTag(ppvNew, cbNew, fFlags, pszTag); } /* * Free operation. Pass it on. */ else { RTMemSaferFree(pvOld, cbOld); *ppvNew = NULL; 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);