fs:[0]到底表示什麼？fs段暫存器在WINDOWS系統中的作用
在進行WINDOWS開發的過程中，有一個重要的地址儲存著每個程式或者說程式碼執行的關鍵資訊，它就是fs:[0]地址的所指向的一塊資料區，它其實就是用來儲存當前程序關鍵資訊的程序控制塊資料結構，在核心態環境下，它表示的是進行控制塊KPCB結構體，在使用者態環境下，它的表示形式是執行緒控制塊的使用者態形式TEB，為了容易閱讀，這裡使用了REACTOS的相關原始碼來描述：
typedef struct _KPCR
{
_ANONYMOUS_UNION union
{
NT_TIB NtTib; //這裡是當前執行緒的控制塊
_ANONYMOUS_STRUCT struct
{
union _KGDTENTRY64 *GdtBase; ///gdt表
struct _KTSS64 *TssBase;
ULONG64 UserRsp;
struct _KPCR *Self;
struct _KPRCB *CurrentPrcb;
PKSPIN_LOCK_QUEUE LockArray;
PVOID Used_Self;
};
};
union _KIDTENTRY64 *IdtBase;
ULONG64 Unused[2];
KIRQL Irql;
UCHAR SecondLevelCacheAssociativity;
UCHAR ObsoleteNumber;
UCHAR Fill0;
ULONG Unused0[3];
USHORT MajorVersion;
USHORT MinorVersion;
ULONG StallScaleFactor;
PVOID Unused1[3];
ULONG KernelReserved[15];
ULONG SecondLevelCacheSize;
ULONG HalReserved[16];
ULONG Unused2;
PVOID KdVersionBlock;
PVOID Unused3;
ULONG PcrAlign1[24];
} KPCR, *PKPCR;
經常會有這樣的使用方式：
mov eax, fs:[0];
mov ecx, dword ptr [ eax ];
這裡訪問的是PCB的第一個成員，就是執行緒控制塊的第一個成員變數，就是ExceptionList，SEH異常控制塊連結串列。
它的結構定義是：
typedef struct _NT_TIB {
struct _EXCEPTION_REGISTRATION_RECORD *ExceptionList; //最常使用的異常控制塊連結串列
PVOID StackBase;
PVOID StackLimit;
PVOID SubSystemTib;
_ANONYMOUS_UNION union {
PVOID FiberData;
ULONG Version;
} DUMMYUNIONNAME;
PVOID ArbitraryUserPointer;
struct _NT_TIB *Self;
} NT_TIB, *PNT_TIB;
使用者態下的TEB結構體的定義：
typedef struct _TEB {
NT_TIB NtTib;
PVOID EnvironmentPointer;
CLIENT_ID ClientId;
PVOID ActiveRpcHandle;
PVOID ThreadLocalStoragePointer;
PPEB ProcessEnvironmentBlock;
ULONG LastErrorValue;
ULONG CountOfOwnedCriticalSections;
PVOID CsrClientThread;
PVOID Win32ThreadInfo; // PtiCurrent
ULONG Win32ClientInfo[WIN32_CLIENT_INFO_LENGTH]; // User32 Client Info
PVOID WOW32Reserved; // used by WOW
LCID CurrentLocale;
ULONG FpSoftwareStatusRegister;
PVOID SystemReserved1[54]; // Used by FP emulator
PVOID Spare1; // unused
NTSTATUS ExceptionCode; // for RaiseUserException
UCHAR SpareBytes1[40];
PVOID SystemReserved2[10]; // Used by user/console for temp obja
GDI_TEB_BATCH GdiTebBatch; // Gdi batching
ULONG gdiRgn;
ULONG gdiPen;
ULONG gdiBrush;
CLIENT_ID RealClientId;
HANDLE GdiCachedProcessHandle;
ULONG GdiClientPID;
ULONG GdiClientTID;
PVOID GdiThreadLocalInfo;
PVOID UserReserved[5]; // unused
PVOID glDispatchTable[280]; // OpenGL
ULONG glReserved1[26]; // OpenGL
PVOID glReserved2; // OpenGL
PVOID glSectionInfo; // OpenGL
PVOID glSection; // OpenGL
PVOID glTable; // OpenGL
PVOID glCurrentRC; // OpenGL
PVOID glContext; // OpenGL
ULONG LastStatusValue;
UNICODE_STRING StaticUnicodeString;
WCHAR StaticUnicodeBuffer[STATIC_UNICODE_BUFFER_LENGTH];
PVOID DeallocationStack;
PVOID TlsSlots[TLS_MINIMUM_AVAILABLE];
LIST_ENTRY TlsLinks;
PVOID Vdm;
PVOID ReservedForNtRpc;
PVOID DbgSsReserved[2];
ULONG HardErrorsAreDisabled;
PVOID Instrumentation[16];
PVOID WinSockData; // WinSock
ULONG GdiBatchCount;
ULONG Spare2;
ULONG Spare3;
ULONG Spare4;
PVOID ReservedForOle;
ULONG WaitingOnLoaderLock;
} TEB;
它的成員ProcessEnvironmentBlock對應的PEB結構的定義：
typedef struct _PEB {
BOOLEAN InheritedAddressSpace; // These four fields cannot change unless the
BOOLEAN ReadImageFileExecOptions; //
BOOLEAN BeingDebugged; //
BOOLEAN SpareBool; //
HANDLE Mutant; // INITIAL_PEB structure is also updated.
PVOID ImageBaseAddress;
PPEB_LDR_DATA Ldr;
struct _RTL_USER_PROCESS_PARAMETERS *ProcessParameters;
PVOID SubSystemData;
PVOID ProcessHeap;
PVOID FastPebLock;
PVOID FastPebLockRoutine;
PVOID FastPebUnlockRoutine;
ULONG EnvironmentUpdateCount;
PVOID KernelCallbackTable;
HANDLE EventLogSection;
PVOID EventLog;
PPEB_FREE_BLOCK FreeList;
ULONG TlsExpansionCounter;
PVOID TlsBitmap;
ULONG TlsBitmapBits[2]; // relates to TLS_MINIMUM_AVAILABLE
PVOID ReadOnlySharedMemoryBase;
PVOID ReadOnlySharedMemoryHeap;
PVOID *ReadOnlyStaticServerData;
PVOID AnsiCodePageData;
PVOID OemCodePageData;
PVOID UnicodeCaseTableData;
// Useful information for LdrpInitialize
ULONG NumberOfProcessors;
ULONG NtGlobalFlag;
// Passed up from MmCreatePeb from Session Manager registry key
LARGE_INTEGER CriticalSectionTimeout;
ULONG HeapSegmentReserve;
ULONG HeapSegmentCommit;
ULONG HeapDeCommitTotalFreeThreshold;
ULONG HeapDeCommitFreeBlockThreshold;
// Where heap manager keeps track of all heaps created for a process
// Fields initialized by MmCreatePeb. ProcessHeaps is initialized
// to point to the first free byte after the PEB and MaximumNumberOfHeaps
// is computed from the page size used to hold the PEB, less the fixed
// size of this data structure.
ULONG NumberOfHeaps;
ULONG MaximumNumberOfHeaps;
PVOID *ProcessHeaps;
//
//
PVOID GdiSharedHandleTable;
PVOID ProcessStarterHelper;
PVOID GdiDCAttributeList;
PVOID LoaderLock;
// Following fields filled in by MmCreatePeb from system values and/or
// image header.
ULONG OSMajorVersion;
ULONG OSMinorVersion;
ULONG OSBuildNumber;
ULONG OSPlatformId;
ULONG ImageSubsystem;
ULONG ImageSubsystemMajorVersion;
ULONG ImageSubsystemMinorVersion;
ULONG ImageProcessAffinityMask;
ULONG GdiHandleBuffer[GDI_HANDLE_BUFFER_SIZE];
} PEB, *PPEB;
真實的WINDOWS定義的形式為：
kd> dt ntkrnlpa!_KPCR
+0x000 NtTib : _NT_TIB
+0x01c SelfPcr : Ptr32 _KPCR
+0x020 Prcb : Ptr32 _KPRCB
+0x024 Irql : UChar
+0x028 IRR : Uint4B
+0x02c IrrActive : Uint4B
+0x030 IDR : Uint4B
+0x034 KdVersionBlock : Ptr32 Void
+0x038 IDT : Ptr32 _KIDTENTRY
+0x03c GDT : Ptr32 _KGDTENTRY
+0x040 TSS : Ptr32 _KTSS
+0x044 MajorVersion : Uint2B
+0x046 MinorVersion : Uint2B
+0x048 SetMember : Uint4B
+0x04c StallScaleFactor : Uint4B
+0x050 DebugActive : UChar
+0x051 Number : UChar
+0x052 Spare0 : UChar
+0x053 SecondLevelCacheAssociativity : UChar
+0x054 VdmAlert : Uint4B
+0x058 KernelReserved : [14] Uint4B
+0x090 SecondLevelCacheSize : Uint4B
+0x094 HalReserved : [16] Uint4B
+0x0d4 InterruptMode : Uint4B
+0x0d8 Spare1 : UChar
+0x0dc KernelReserved2 : [17] Uint4B
+0x120 PrcbData : _KPRCB
它的第3個成員Prcb的KPRCB結構的定義為：
dt ntkrnlpa!_KPRCB
+0x000 MinorVersion : Uint2B
+0x002 MajorVersion : Uint2B
+0x004 CurrentThread : Ptr32 _KTHREAD
+0x008 NextThread : Ptr32 _KTHREAD
+0x00c IdleThread : Ptr32 _KTHREAD
+0x010 Number : Char
+0x011 Reserved : Char
+0x012 BuildType : Uint2B
+0x014 SetMember : Uint4B
+0x018 CpuType : Char
+0x019 CpuID : Char
+0x01a CpuStep : Uint2B
+0x01c ProcessorState : _KPROCESSOR_STATE
+0x33c KernelReserved : [16] Uint4B
+0x37c HalReserved : [16] Uint4B
+0x3bc PrcbPad0 : [92] UChar
+0x418 LockQueue : [16] _KSPIN_LOCK_QUEUE
+0x498 PrcbPad1 : [8] UChar
+0x4a0 NpxThread : Ptr32 _KTHREAD
+0x4a4 InterruptCount : Uint4B
+0x4a8 KernelTime : Uint4B
+0x4ac UserTime : Uint4B
+0x4b0 DpcTime : Uint4B
+0x4b4 DebugDpcTime : Uint4B
+0x4b8 InterruptTime : Uint4B
+0x4bc AdjustDpcThreshold : Uint4B
+0x4c0 PageColor : Uint4B
+0x4c4 SkipTick : Uint4B
+0x4c8 MultiThreadSetBusy : UChar
+0x4c9 Spare2 : [3] UChar
+0x4cc ParentNode : Ptr32 _KNODE
+0x4d0 MultiThreadProcessorSet : Uint4B
+0x4d4 MultiThreadSetMaster : Ptr32 _KPRCB
+0x4d8 ThreadStartCount : [2] Uint4B
+0x4e0 CcFastReadNoWait : Uint4B
+0x4e4 CcFastReadWait : Uint4B
+0x4e8 CcFastReadNotPossible : Uint4B
+0x4ec CcCopyReadNoWait : Uint4B
+0x4f0 CcCopyReadWait : Uint4B
+0x4f4 CcCopyReadNoWaitMiss : Uint4B
+0x4f8 KeAlignmentFixupCount : Uint4B
+0x4fc KeContextSwitches : Uint4B
+0x500 KeDcacheFlushCount : Uint4B
+0x504 KeExceptionDispatchCount : Uint4B
+0x508 KeFirstLevelTbFills : Uint4B
+0x50c KeFloatingEmulationCount : Uint4B
+0x510 KeIcacheFlushCount : Uint4B
+0x514 KeSecondLevelTbFills : Uint4B
+0x518 KeSystemCalls : Uint4B
+0x51c SpareCounter0 : [1] Uint4B
+0x520 PPLookasideList : [16] _PP_LOOKASIDE_LIST
+0x5a0 PPNPagedLookasideList : [32] _PP_LOOKASIDE_LIST
+0x6a0 PPPagedLookasideList : [32] _PP_LOOKASIDE_LIST
+0x7a0 PacketBarrier : Uint4B
+0x7a4 ReverseStall : Uint4B
+0x7a8 IpiFrame : Ptr32 Void
+0x7ac PrcbPad2 : [52] UChar
+0x7e0 CurrentPacket : [3] Ptr32 Void
+0x7ec TargetSet : Uint4B
+0x7f0 WorkerRoutine : Ptr32 void
+0x7f4 IpiFrozen : Uint4B
+0x7f8 PrcbPad3 : [40] UChar
+0x820 RequestSummary : Uint4B
+0x824 SignalDone : Ptr32 _KPRCB
+0x828 PrcbPad4 : [56] UChar
+0x860 DpcListHead : _LIST_ENTRY
+0x868 DpcStack : Ptr32 Void
+0x86c DpcCount : Uint4B
+0x870 DpcQueueDepth : Uint4B
+0x874 DpcRoutineActive : Uint4B
+0x878 DpcInterruptRequested : Uint4B
+0x87c DpcLastCount : Uint4B
+0x880 DpcRequestRate : Uint4B
+0x884 MaximumDpcQueueDepth : Uint4B
+0x888 MinimumDpcRate : Uint4B
+0x88c QuantumEnd : Uint4B
+0x890 PrcbPad5 : [16] UChar
+0x8a0 DpcLock : Uint4B
+0x8a4 PrcbPad6 : [28] UChar
+0x8c0 CallDpc : _KDPC
+0x8e0 ChainedInterruptList : Ptr32 Void
+0x8e4 LookasideIrpFloat : Int4B
+0x8e8 SpareFields0 : [6] Uint4B
+0x900 VendorString : [13] UChar
+0x90d InitialApicId : UChar
+0x90e LogicalProcessorsPerPhysicalProcessor : UChar
+0x910 MHz : Uint4B
+0x914 FeatureBits : Uint4B
+0x918 UpdateSignature : _LARGE_INTEGER
+0x920 NpxSaveArea : _FX_SAVE_AREA
+0xb30 PowerState : _PROCESSOR_POWER_STATE
第1個成員NtTib對應的NT_TIB結構定義如下：
nt!_NT_TIB
+0x000 ExceptionList : Ptr32 _EXCEPTION_REGISTRATION_RECORD
+0x004 StackBase : Ptr32 Void
+0x008 StackLimit : Ptr32 Void
+0x00c SubSystemTib : Ptr32 Void
+0x010 FiberData : Ptr32 Void
+0x010 Version : Uint4B
+0x014 ArbitraryUserPointer : Ptr32 Void
+0x018 Self : Ptr32 _NT_TIB
在使用者態環境下，fs:[0]對應的TEB結構定義：
dt nt!_TEB
+0x000 NtTib : _NT_TIB
+0x01c EnvironmentPointer : Ptr32 Void
+0x020 ClientId : _CLIENT_ID
+0x028 ActiveRpcHandle : Ptr32 Void
+0x02c ThreadLocalStoragePointer : Ptr32 Void
+0x030 ProcessEnvironmentBlock : Ptr32 _PEB
+0x034 LastErrorValue : Uint4B
+0x038 CountOfOwnedCriticalSections : Uint4B
+0x03c CsrClientThread : Ptr32 Void
+0x040 Win32ThreadInfo : Ptr32 Void
+0x044 User32Reserved : [26] Uint4B
+0x0ac UserReserved : [5] Uint4B
+0x0c0 WOW32Reserved : Ptr32 Void
+0x0c4 CurrentLocale : Uint4B
+0x0c8 FpSoftwareStatusRegister : Uint4B
+0x0cc SystemReserved1 : [54] Ptr32 Void
+0x1a4 ExceptionCode : Int4B
+0x1a8 ActivationContextStack : _ACTIVATION_CONTEXT_STACK
+0x1bc SpareBytes1 : [24] UChar
+0x1d4 GdiTebBatch : _GDI_TEB_BATCH
+0x6b4 RealClientId : _CLIENT_ID
+0x6bc GdiCachedProcessHandle : Ptr32 Void
+0x6c0 GdiClientPID : Uint4B
+0x6c4 GdiClientTID : Uint4B
+0x6c8 GdiThreadLocalInfo : Ptr32 Void
+0x6cc Win32ClientInfo : [62] Uint4B
+0x7c4 glDispatchTable : [233] Ptr32 Void
+0xb68 glReserved1 : [29] Uint4B
+0xbdc glReserved2 : Ptr32 Void
+0xbe0 glSectionInfo : Ptr32 Void
+0xbe4 glSection : Ptr32 Void
+0xbe8 glTable : Ptr32 Void
+0xbec glCurrentRC : Ptr32 Void
+0xbf0 glContext : Ptr32 Void
+0xbf4 LastStatusValue : Uint4B
+0xbf8 StaticUnicodeString : _UNICODE_STRING
+0xc00 StaticUnicodeBuffer : [261] Uint2B
+0xe0c DeallocationStack : Ptr32 Void
+0xe10 TlsSlots : [64] Ptr32 Void
+0xf10 TlsLinks : _LIST_ENTRY
+0xf18 Vdm : Ptr32 Void
+0xf1c ReservedForNtRpc : Ptr32 Void
+0xf20 DbgSsReserved : [2] Ptr32 Void
+0xf28 HardErrorsAreDisabled : Uint4B
+0xf2c Instrumentation : [16] Ptr32 Void
+0xf6c WinSockData : Ptr32 Void
+0xf70 GdiBatchCount : Uint4B
+0xf74 InDbgPrint : UChar
+0xf75 FreeStackOnTermination : UChar
+0xf76 HasFiberData : UChar
+0xf77 IdealProcessor : UChar
+0xf78 Spare3 : Uint4B
+0xf7c ReservedForPerf : Ptr32 Void
+0xf80 ReservedForOle : Ptr32 Void
+0xf84 WaitingOnLoaderLock : Uint4B
+0xf88 Wx86Thread : _Wx86ThreadState
+0xf94 TlsExpansionSlots : Ptr32 Ptr32 Void
+0xf98 ImpersonationLocale : Uint4B
+0xf9c IsImpersonating : Uint4B
+0xfa0 NlsCache : Ptr32 Void
+0xfa4 pShimData : Ptr32 Void
+0xfa8 HeapVirtualAffinity : Uint4B
+0xfac CurrentTransactionHandle : Ptr32 Void
+0xfb0 ActiveFrame : Ptr32 _TEB_ACTIVE_FRAME
+0xfb4 SafeThunkCall : UChar
+0xfb5 BooleanSpare : [3] UChar
它的成員ProcessEnvironmentBlock對應的_PEB結構的定義：
nt!_PEB
+0x000 InheritedAddressSpace : UChar
+0x001 ReadImageFileExecOptions : UChar
+0x002 BeingDebugged : UChar
+0x003 SpareBool : UChar
+0x004 Mutant : Ptr32 Void
+0x008 ImageBaseAddress : Ptr32 Void
+0x00c Ldr : Ptr32 _PEB_LDR_DATA
+0x010 ProcessParameters : Ptr32 _RTL_USER_PROCESS_PARAMETERS
+0x014 SubSystemData : Ptr32 Void
+0x018 ProcessHeap : Ptr32 Void
+0x01c FastPebLock : Ptr32 _RTL_CRITICAL_SECTION
+0x020 FastPebLockRoutine : Ptr32 Void
+0x024 FastPebUnlockRoutine : Ptr32 Void
+0x028 EnvironmentUpdateCount : Uint4B
+0x02c KernelCallbackTable : Ptr32 Void
+0x030 SystemReserved : [1] Uint4B
+0x034 AtlThunkSListPtr32 : Uint4B
+0x038 FreeList : Ptr32 _PEB_FREE_BLOCK
+0x03c TlsExpansionCounter : Uint4B
+0x040 TlsBitmap : Ptr32 Void
+0x044 TlsBitmapBits : [2] Uint4B
+0x04c ReadOnlySharedMemoryBase : Ptr32 Void
+0x050 ReadOnlySharedMemoryHeap : Ptr32 Void
+0x054 ReadOnlyStaticServerData : Ptr32 Ptr32 Void
+0x058 AnsiCodePageData : Ptr32 Void
+0x05c OemCodePageData : Ptr32 Void
+0x060 UnicodeCaseTableData : Ptr32 Void
+0x064 NumberOfProcessors : Uint4B
+0x068 NtGlobalFlag : Uint4B
+0x070 CriticalSectionTimeout : _LARGE_INTEGER
+0x078 HeapSegmentReserve : Uint4B
+0x07c HeapSegmentCommit : Uint4B
+0x080 HeapDeCommitTotalFreeThreshold : Uint4B
+0x084 HeapDeCommitFreeBlockThreshold : Uint4B
+0x088 NumberOfHeaps : Uint4B
+0x08c MaximumNumberOfHeaps : Uint4B
+0x090 ProcessHeaps : Ptr32 Ptr32 Void
+0x094 GdiSharedHandleTable : Ptr32 Void
+0x098 ProcessStarterHelper : Ptr32 Void
+0x09c GdiDCAttributeList : Uint4B
+0x0a0 LoaderLock : Ptr32 Void
+0x0a4 OSMajorVersion : Uint4B
+0x0a8 OSMinorVersion : Uint4B
+0x0ac OSBuildNumber : Uint2B
+0x0ae OSCSDVersion : Uint2B
+0x0b0 OSPlatformId : Uint4B
+0x0b4 ImageSubsystem : Uint4B
+0x0b8 ImageSubsystemMajorVersion : Uint4B
+0x0bc ImageSubsystemMinorVersion : Uint4B
+0x0c0 ImageProcessAffinityMask : Uint4B
+0x0c4 GdiHandleBuffer : [34] Uint4B
+0x14c PostProcessInitRoutine : Ptr32 void
+0x150 TlsExpansionBitmap : Ptr32 Void
+0x154 TlsExpansionBitmapBits : [32] Uint4B
+0x1d4 SessionId : Uint4B
+0x1d8 AppCompatFlags : _ULARGE_INTEGER
+0x1e0 AppCompatFlagsUser : _ULARGE_INTEGER
+0x1e8 pShimData : Ptr32 Void
+0x1ec AppCompatInfo : Ptr32 Void
+0x1f0 CSDVersion : _UNICODE_STRING
+0x1f8 ActivationContextData : Ptr32 Void
+0x1fc ProcessAssemblyStorageMap : Ptr32 Void
+0x200 SystemDefaultActivationContextData : Ptr32 Void
+0x204 SystemAssemblyStorageMap : Ptr32 Void
+0x208 MinimumStackCommit : Uint4B
使用以上資訊來查詢相關的資料訪問指令，可以搞清楚操作的含義。