在上一篇文章《驱动开发：内核中实现Dump进程转储》中我们实现了ARK工具的转存功能，本篇文章继续以内存为出发点介绍VAD结构，该结构的全程是Virtual Address Descriptor即虚拟地址描述符，VAD是一个AVL自平衡二叉树，树的每一个节点代表一段虚拟地址空间。程序中的代码段，数据段，堆段都会各种占用一个或多个VAD节点，由一个MMVAD结构完整描述。
VAD结构的遍历效果如下:
那么这个结构在哪？每一个进程都有自己单独的VAD结构树，这个结构通常在EPROCESS结构里面里面，在内核调试模式下使用dt _EPROCESS可得到如下信息。
1: kd> dt _EPROCESS
ntdll!_EPROCESS
+0x500 Vm : _MMSUPPORT_FULL
+0x640 MmProcessLinks : _LIST_ENTRY
+0x650 ModifiedPageCount : Uint4B
+0x654 ExitStatus : Int4B
+0x658 VadRoot : _RTL_AVL_TREE
+0x660 VadHint : Ptr64 Void
+0x668 VadCount : Uint8B
+0x670 VadPhysicalPages : Uint8B
+0x678 VadPhysicalPagesLimit : Uint8B
可以看到在本系统中VAD的偏移是+0x658紧跟其后的还有vadCount的计数等。
VAD结构是如何被添加的？通常情况下系统调用VirtualAllocate等申请一段堆内存时，则会在VAD树上增加一个结点_MMVAD结构体，需要说明的是栈并不受VAD的管理。由系统直接分配空间，并把地址记录在了TEB中。
0: kd> dt _MMVAD
nt!_MMVAD
+0x000 Core : _MMVAD_SHORT
+0x040 u2 : <anonymous-tag>
+0x048 Subsection : Ptr64 _SUBSECTION
+0x050 FirstPrototypePte : Ptr64 _MMPTE
+0x058 LastContiguousPte : Ptr64 _MMPTE
+0x060 ViewLinks : _LIST_ENTRY
+0x070 VadsProcess : Ptr64 _EPROCESS
+0x078 u4 : <anonymous-tag>
+0x080 FileObject : Ptr64 _FILE_OBJECT
结构体MMVAD则是每一个VAD内存块的属性，这个内存结构定义在WinDBG中可看到。
如上在EPROCESS结构中可以找到VAD结构的相对偏移+0x658以及进程VAD计数偏移+0x668，我们首先通过!process 0 0指令得到当前所有进程的EPROCESS结构，并选中进程。
0: kd> !process 0 0
PROCESS ffffe28fbb0860c0
SessionId: 1 Cid: 11a8 Peb: 0035c000 ParentCid: 11c8
DirBase: 309f3002 ObjectTable: ffffac87ba3da580 HandleCount: 145.
Image: x64.exe
此处的ffffe28fbb0860c0正是我们所需要的EPROCESS结构。
当需要得到该进程的VAD结构时，只需要使用!vad ffffe28fbb0860c0 + 0x658来显示该进程的VAD树。
至于获取VAD有多少条，则可以直接使用!vad ffffe28fbb0860c0 + 0x668来获取到。
既然手动可以遍历出来，那么自动化也并不难，首先定义头文件vad.h同样这是微软定义，如果想要的到最新的，自己下载WinDBG调试内核输入命令。
#pragma once
#include <ntifs.h>
typedef struct _MM_GRAPHICS_VAD_FLAGS // 15 elements, 0x4 bytes (sizeof)
{
/*0x000*/ ULONG32 Lock : 1; // 0 BitPosition
/*0x000*/ ULONG32 LockContended : 1; // 1 BitPosition
/*0x000*/ ULONG32 DeleteInProgress : 1; // 2 BitPosition
/*0x000*/ ULONG32 NoChange : 1; // 3 BitPosition
/*0x000*/ ULONG32 VadType : 3; // 4 BitPosition
/*0x000*/ ULONG32 Protection : 5; // 7 BitPosition
/*0x000*/ ULONG32 PreferredNode : 6; // 12 BitPosition
/*0x000*/ ULONG32 PageSize : 2; // 18 BitPosition
/*0x000*/ ULONG32 PrivateMemoryAlwaysSet : 1; // 20 BitPosition
/*0x000*/ ULONG32 WriteWatch : 1; // 21 BitPosition
/*0x000*/ ULONG32 FixedLargePageSize : 1; // 22 BitPosition
/*0x000*/ ULONG32 ZeroFillPagesOptional : 1; // 23 BitPosition
/*0x000*/ ULONG32 GraphicsAlwaysSet : 1; // 24 BitPosition
/*0x000*/ ULONG32 GraphicsUseCoherentBus : 1; // 25 BitPosition
/*0x000*/ ULONG32 GraphicsPageProtection : 3; // 26 BitPosition
}MM_GRAPHICS_VAD_FLAGS, *PMM_GRAPHICS_VAD_FLAGS;
typedef struct _MM_PRIVATE_VAD_FLAGS // 15 elements, 0x4 bytes (sizeof)
{
/*0x000*/ ULONG32 Lock : 1; // 0 BitPosition
/*0x000*/ ULONG32 LockContended : 1; // 1 BitPosition
/*0x000*/ ULONG32 DeleteInProgress : 1; // 2 BitPosition
/*0x000*/ ULONG32 NoChange : 1; // 3 BitPosition
/*0x000*/ ULONG32 VadType : 3; // 4 BitPosition
/*0x000*/ ULONG32 Protection : 5; // 7 BitPosition
/*0x000*/ ULONG32 PreferredNode : 6; // 12 BitPosition
/*0x000*/ ULONG32 PageSize : 2; // 18 BitPosition
/*0x000*/ ULONG32 PrivateMemoryAlwaysSet : 1; // 20 BitPosition
/*0x000*/ ULONG32 WriteWatch : 1; // 21 BitPosition
/*0x000*/ ULONG32 FixedLargePageSize : 1; // 22 BitPosition
/*0x000*/ ULONG32 ZeroFillPagesOptional : 1; // 23 BitPosition
/*0x000*/ ULONG32 Graphics : 1; // 24 BitPosition
/*0x000*/ ULONG32 Enclave : 1; // 25 BitPosition
/*0x000*/ ULONG32 ShadowStack : 1; // 26 BitPosition
}MM_PRIVATE_VAD_FLAGS, *PMM_PRIVATE_VAD_FLAGS;
typedef struct _MMVAD_FLAGS // 9 elements, 0x4 bytes (sizeof)
{
/*0x000*/ ULONG32 Lock : 1; // 0 BitPosition
/*0x000*/ ULONG32 LockContended : 1; // 1 BitPosition
/*0x000*/ ULONG32 DeleteInProgress : 1; // 2 BitPosition
/*0x000*/ ULONG32 NoChange : 1; // 3 BitPosition
/*0x000*/ ULONG32 VadType : 3; // 4 BitPosition
/*0x000*/ ULONG32 Protection : 5; // 7 BitPosition
/*0x000*/ ULONG32 PreferredNode : 6; // 12 BitPosition
/*0x000*/ ULONG32 PageSize : 2; // 18 BitPosition
/*0x000*/ ULONG32 PrivateMemory : 1; // 20 BitPosition
}MMVAD_FLAGS, *PMMVAD_FLAGS;
typedef struct _MM_SHARED_VAD_FLAGS // 11 elements, 0x4 bytes (sizeof)
{
/*0x000*/ ULONG32 Lock : 1; // 0 BitPosition
/*0x000*/ ULONG32 LockContended : 1; // 1 BitPosition
/*0x000*/ ULONG32 DeleteInProgress : 1; // 2 BitPosition
/*0x000*/ ULONG32 NoChange : 1; // 3 BitPosition
/*0x000*/ ULONG32 VadType : 3; // 4 BitPosition
/*0x000*/ ULONG32 Protection : 5; // 7 BitPosition
/*0x000*/ ULONG32 PreferredNode : 6; // 12 BitPosition
/*0x000*/ ULONG32 PageSize : 2; // 18 BitPosition
/*0x000*/ ULONG32 PrivateMemoryAlwaysClear : 1; // 20 BitPosition
/*0x000*/ ULONG32 PrivateFixup : 1; // 21 BitPosition
/*0x000*/ ULONG32 HotPatchAllowed : 1; // 22 BitPosition
}MM_SHARED_VAD_FLAGS, *PMM_SHARED_VAD_FLAGS;
typedef struct _MMVAD_FLAGS2 // 7 elements, 0x4 bytes (sizeof)
{
/*0x000*/ ULONG32 FileOffset : 24; // 0 BitPosition
/*0x000*/ ULONG32 Large : 1; // 24 BitPosition
/*0x000*/ ULONG32 TrimBehind : 1; // 25 BitPosition
/*0x000*/ ULONG32 Inherit : 1; // 26 BitPosition
/*0x000*/ ULONG32 NoValidationNeeded : 1; // 27 BitPosition
/*0x000*/ ULONG32 PrivateDemandZero : 1; // 28 BitPosition
/*0x000*/ ULONG32 Spare : 3; // 29 BitPosition
}MMVAD_FLAGS2, *PMMVAD_FLAGS2;
typedef struct _MMVAD_SHORT
{
RTL_BALANCED_NODE VadNode;
UINT32 StartingVpn; /*0x18*/
UINT32 EndingVpn; /*0x01C*/
UCHAR StartingVpnHigh;
UCHAR EndingVpnHigh;
UCHAR CommitChargeHigh;
UCHAR SpareNT64VadUChar;
INT32 ReferenceCount;
EX_PUSH_LOCK PushLock; /*0x028*/
struct
{
union
{
ULONG_PTR flag;
MM_PRIVATE_VAD_FLAGS PrivateVadFlags; /*0x030*/
MMVAD_FLAGS VadFlags;
MM_GRAPHICS_VAD_FLAGS GraphicsVadFlags;
MM_SHARED_VAD_FLAGS SharedVadFlags;
}Flags;
}u1;
PVOID EventList; /*0x038*/
}MMVAD_SHORT, *PMMVAD_SHORT;
typedef struct _MMADDRESS_NODE
{
ULONG64 u1;
struct _MMADDRESS_NODE* LeftChild;
struct _MMADDRESS_NODE* RightChild;
ULONG64 StartingVpn;
ULONG64 EndingVpn;
}MMADDRESS_NODE, *PMMADDRESS_NODE;
typedef struct _MMEXTEND_INFO // 2 elements, 0x10 bytes (sizeof)
{
/*0x000*/ UINT64 CommittedSize;
/*0x008*/ ULONG32 ReferenceCount;
/*0x00C*/ UINT8 _PADDING0_[0x4];
}MMEXTEND_INFO, *PMMEXTEND_INFO;
struct _SEGMENT
{
struct _CONTROL_AREA* ControlArea;
ULONG TotalNumberOfPtes;
ULONG SegmentFlags;
ULONG64 NumberOfCommittedPages;
ULONG64 SizeOfSegment;
union
{
struct _MMEXTEND_INFO* ExtendInfo;
void* BasedAddress;
}u;
ULONG64 SegmentLock;
ULONG64 u1;
ULONG64 u2;
PVOID* PrototypePte;
ULONGLONG ThePtes[0x1];
};
typedef struct _EX_FAST_REF
{
union
{
PVOID Object;
ULONG_PTR RefCnt : 3;
ULONG_PTR Value;
};
} EX_FAST_REF, *PEX_FAST_REF;
typedef struct _CONTROL_AREA // 17 elements, 0x80 bytes (sizeof)
{
/*0x000*/ struct _SEGMENT* Segment;
union // 2 elements, 0x10 bytes (sizeof)
{
/*0x008*/ struct _LIST_ENTRY ListHead; // 2 elements, 0x10 bytes (sizeof)
/*0x008*/ VOID* AweContext;
};
/*0x018*/ UINT64 NumberOfSectionReferences;
/*0x020*/ UINT64 NumberOfPfnReferences;
/*0x028*/ UINT64 NumberOfMappedViews;
/*0x030*/ UINT64 NumberOfUserReferences;
/*0x038*/ ULONG32 u; // 2 elements, 0x4 bytes (sizeof)
/*0x03C*/ ULONG32 u1; // 2 elements, 0x4 bytes (sizeof)
/*0x040*/ struct _EX_FAST_REF FilePointer; // 3 elements, 0x8 bytes (sizeof)
// 4 elements, 0x8 bytes (sizeof)
}CONTROL_AREA, *PCONTROL_AREA;
typedef struct _SUBSECTION_
{
struct _CONTROL_AREA* ControlArea;
}SUBSECTION, *PSUBSECTION;
typedef struct _MMVAD
{
MMVAD_SHORT Core;
union /*0x040*/
{
UINT32 LongFlags2;
//现在用不到省略
MMVAD_FLAGS2 VadFlags2;
}u2;
PSUBSECTION Subsection; /*0x048*/
PVOID FirstPrototypePte; /*0x050*/
PVOID LastContiguousPte; /*0x058*/
LIST_ENTRY ViewLinks; /*0x060*/
PEPROCESS VadsProcess; /*0x070*/
PVOID u4; /*0x078*/
PVOID FileObject; /*0x080*/
}MMVAD, *PMMVAD;
typedef struct _RTL_AVL_TREE // 1 elements, 0x8 bytes (sizeof)
{
/*0x000*/ struct _RTL_BALANCED_NODE* Root;
}RTL_AVL_TREE, *PRTL_AVL_TREE;
typedef struct _VAD_INFO_
{
ULONG_PTR pVad;
ULONG_PTR startVpn;
ULONG_PTR endVpn;
ULONG_PTR pFileObject;
ULONG_PTR flags;
}VAD_INFO, *PVAD_INFO;
typedef struct _ALL_VADS_
{
ULONG nCnt;
VAD_INFO VadInfos[1];
}ALL_VADS, *PALL_VADS;
typedef struct _MMSECTION_FLAGS // 27 elements, 0x4 bytes (sizeof)
{
/*0x000*/ UINT32 BeingDeleted : 1; // 0 BitPosition
/*0x000*/ UINT32 BeingCreated : 1; // 1 BitPosition
/*0x000*/ UINT32 BeingPurged : 1; // 2 BitPosition
/*0x000*/ UINT32 NoModifiedWriting : 1; // 3 BitPosition
/*0x000*/ UINT32 FailAllIo : 1; // 4 BitPosition
/*0x000*/ UINT32 Image : 1; // 5 BitPosition
/*0x000*/ UINT32 Based : 1; // 6 BitPosition
/*0x000*/ UINT32 File : 1; // 7 BitPosition
/*0x000*/ UINT32 AttemptingDelete : 1; // 8 BitPosition
/*0x000*/ UINT32 PrefetchCreated : 1; // 9 BitPosition
/*0x000*/ UINT32 PhysicalMemory : 1; // 10 BitPosition
/*0x000*/ UINT32 ImageControlAreaOnRemovableMedia : 1; // 11 BitPosition
/*0x000*/ UINT32 Reserve : 1; // 12 BitPosition
/*0x000*/ UINT32 Commit : 1; // 13 BitPosition
/*0x000*/ UINT32 NoChange : 1; // 14 BitPosition
/*0x000*/ UINT32 WasPurged : 1; // 15 BitPosition
/*0x000*/ UINT32 UserReference : 1; // 16 BitPosition
/*0x000*/ UINT32 GlobalMemory : 1; // 17 BitPosition
/*0x000*/ UINT32 DeleteOnClose : 1; // 18 BitPosition
/*0x000*/ UINT32 FilePointerNull : 1; // 19 BitPosition
/*0x000*/ ULONG32 PreferredNode : 6; // 20 BitPosition
/*0x000*/ UINT32 GlobalOnlyPerSession : 1; // 26 BitPosition
/*0x000*/ UINT32 UserWritable : 1; // 27 BitPosition
/*0x000*/ UINT32 SystemVaAllocated : 1; // 28 BitPosition
/*0x000*/ UINT32 PreferredFsCompressionBoundary : 1; // 29 BitPosition
/*0x000*/ UINT32 UsingFileExtents : 1; // 30 BitPosition
/*0x000*/ UINT32 PageSize64K : 1; // 31 BitPosition
}MMSECTION_FLAGS, *PMMSECTION_FLAGS;
typedef struct _SECTION // 9 elements, 0x40 bytes (sizeof)
{
/*0x000*/ struct _RTL_BALANCED_NODE SectionNode; // 6 elements, 0x18 bytes (sizeof)
/*0x018*/ UINT64 StartingVpn;
/*0x020*/ UINT64 EndingVpn;
/*0x028*/ union {
PCONTROL_AREA ControlArea;
PVOID FileObject;
}u1; // 4 elements, 0x8 bytes (sizeof)
/*0x030*/ UINT64 SizeOfSection;
/*0x038*/ union {
ULONG32 LongFlags;
MMSECTION_FLAGS Flags;
}u; // 2 elements, 0x4 bytes (sizeof)
struct // 3 elements, 0x4 bytes (sizeof)
{
/*0x03C*/ ULONG32 InitialPageProtection : 12; // 0 BitPosition
/*0x03C*/ ULONG32 SessionId : 19; // 12 BitPosition
/*0x03C*/ ULONG32 NoValidationNeeded : 1; // 31 BitPosition
};
}SECTION, *PSECTION;
引入vad.h头文件，并写入如下代码，此处的eprocess_offset_VadRoot以及eprocess_offset_VadCount 则是上方得出的相对于EPROCESS结构的偏移值，每个系统都不一样，版本不同偏移值会不同。
#include "vad.h"
#include <ntifs.h>
// 定义VAD相对于EProcess头部偏移值
#define eprocess_offset_VadRoot 0x658
#define eprocess_offset_VadCount 0x668
VOID EnumVad(PMMVAD Root, PALL_VADS pBuffer, ULONG nCnt)
{
if (!Root || !pBuffer || !nCnt)
{
return;
}
__try
{
if (nCnt > pBuffer->nCnt)
{
// 得到起始页与结束页
ULONG64 endptr = (ULONG64)Root->Core.EndingVpnHigh;
endptr = endptr << 32;
ULONG64 startptr = (ULONG64)Root->Core.StartingVpnHigh;
startptr = startptr << 32;
// 得到根节点
pBuffer->VadInfos[pBuffer->nCnt].pVad = (ULONG_PTR)Root;
// 起始页: startingVpn * 0x1000
pBuffer->VadInfos[pBuffer->nCnt].startVpn = (startptr | Root->Core.StartingVpn) << PAGE_SHIFT;
// 结束页: EndVpn * 0x1000 + 0xfff
pBuffer->VadInfos[pBuffer->nCnt].endVpn = ((endptr | Root->Core.EndingVpn) << PAGE_SHIFT) + 0xfff;
// VAD标志 928 = Mapped 1049088 = Private ....
pBuffer->VadInfos[pBuffer->nCnt].flags = Root->Core.u1.Flags.flag;
// 验证节点可读性
if (MmIsAddressValid(Root->Subsection) && MmIsAddressValid(Root->Subsection->ControlArea))
{
if (MmIsAddressValid((PVOID)((Root->Subsection->ControlArea->FilePointer.Value >> 4) << 4)))
{
pBuffer->VadInfos[pBuffer->nCnt].pFileObject = ((Root->Subsection->ControlArea->FilePointer.Value >> 4) << 4);
}
}
pBuffer->nCnt++;
}
if (MmIsAddressValid(Root->Core.VadNode.Left))
{
// 递归枚举左子树
EnumVad((PMMVAD)Root->Core.VadNode.Left, pBuffer, nCnt);
}
if (MmIsAddressValid(Root->Core.VadNode.Right))
{
// 递归枚举右子树
EnumVad((PMMVAD)Root->Core.VadNode.Right, pBuffer, nCnt);
}
}
__except (1)
{
}
}
BOOLEAN EnumProcessVad(ULONG Pid, PALL_VADS pBuffer, ULONG nCnt)
{
PEPROCESS Peprocess = 0;
PRTL_AVL_TREE Table = NULL;
PMMVAD Root = NULL;
// 通过进程PID得到进程EProcess
if (NT_SUCCESS(PsLookupProcessByProcessId((HANDLE)Pid, &Peprocess)))
{
// 与偏移相加得到VAD头节点
Table = (PRTL_AVL_TREE)((UCHAR*)Peprocess + eprocess_offset_VadRoot);
if (!MmIsAddressValid(Table) || !eprocess_offset_VadRoot)
{
return FALSE;
}
__try
{
// 取出头节点
Root = (PMMVAD)Table->Root;
if (nCnt > pBuffer->nCnt)
{
// 得到起始页与结束页
ULONG64 endptr = (ULONG64)Root->Core.EndingVpnHigh;
endptr = endptr << 32;
ULONG64 startptr = (ULONG64)Root->Core.StartingVpnHigh;
startptr = startptr << 32;
pBuffer->VadInfos[pBuffer->nCnt].pVad = (ULONG_PTR)Root;
// 起始页: startingVpn * 0x1000
pBuffer->VadInfos[pBuffer->nCnt].startVpn = (startptr | Root->Core.StartingVpn) << PAGE_SHIFT;
// 结束页: EndVpn * 0x1000 + 0xfff
pBuffer->VadInfos[pBuffer->nCnt].endVpn = (endptr | Root->Core.EndingVpn) << PAGE_SHIFT;
pBuffer->VadInfos[pBuffer->nCnt].flags = Root->Core.u1.Flags.flag;
if (MmIsAddressValid(Root->Subsection) && MmIsAddressValid(Root->Subsection->ControlArea))
{
if (MmIsAddressValid((PVOID)((Root->Subsection->ControlArea->FilePointer.Value >> 4) << 4)))
{
pBuffer->VadInfos[pBuffer->nCnt].pFileObject = ((Root->Subsection->ControlArea->FilePointer.Value >> 4) << 4);
}
}
pBuffer->nCnt++;
}
// 枚举左子树
if (Table->Root->Left)
{
EnumVad((MMVAD*)Table->Root->Left, pBuffer, nCnt);
}
// 枚举右子树
if (Table->Root->Right)
{
EnumVad((MMVAD*)Table->Root->Right, pBuffer, nCnt);
}
}
__finally
{
ObDereferenceObject(Peprocess);
}
}
else
{
return FALSE;
}
return TRUE;
}
VOID UnDriver(PDRIVER_OBJECT driver)
{
DbgPrint(("Uninstall Driver Is OK \n"));
}
NTSTATUS DriverEntry(IN PDRIVER_OBJECT Driver, PUNICODE_STRING RegistryPath)
{
DbgPrint(("hello lyshark \n"));
typedef struct
{
ULONG nPid;
ULONG nSize;
PALL_VADS pBuffer;
}VADProcess;
__try
{
VADProcess vad = { 0 };
vad.nPid = 4520;
// 默认有1000个线程
vad.nSize = sizeof(VAD_INFO) * 0x5000 + sizeof(ULONG);
// 分配临时空间
vad.pBuffer = (PALL_VADS)ExAllocatePool(PagedPool, vad.nSize);
// 根据传入长度得到枚举数量
ULONG nCount = (vad.nSize - sizeof(ULONG)) / sizeof(VAD_INFO);
// 枚举VAD
EnumProcessVad(vad.nPid, vad.pBuffer, nCount);
// 输出VAD
for (size_t i = 0; i < vad.pBuffer->nCnt; i++)
{
DbgPrint("StartVPN = %p | ", vad.pBuffer->VadInfos[i].startVpn);
DbgPrint("EndVPN = %p | ", vad.pBuffer->VadInfos[i].endVpn);
DbgPrint("PVAD = %p | ", vad.pBuffer->VadInfos[i].pVad);
DbgPrint("Flags = %d | ", vad.pBuffer->VadInfos[i].flags);
DbgPrint("pFileObject = %p \n", vad.pBuffer->VadInfos[i].pFileObject);
}
}
__except (1)
{
}
Driver->DriverUnload = UnDriver;
return STATUS_SUCCESS;
}
程序运行后输出效果如下：
