win下SSDT-Hook

#include <ntifs.h>
#pragma pack(1)

//SSDTHook中，我们有2个关键问题：
//1 怎么找到SSDT，这个表是导出的，所以直接声明就可以
//2 SSDT是只读的，怎么改
//  2.1 通过修改CR0 去掉内核层的页保护
//  2.2 可以通过MDL重映射的方式，去修改。

typedef struct _ServiceDesriptorEntry
{
    ULONG *ServiceTableBase;        // 服务表基址
    ULONG *ServiceCounterTableBase; // 计数表基址
    ULONG NumberOfServices;         // 表中项的个数
    UCHAR *ParamTableBase;          // 参数表基址
}SSDTEntry, *PSSDTEntry;
#pragma pack()
ULONG         g_uProtectPID;
// 导入SSDT
NTSYSAPI SSDTEntry KeServiceDescriptorTable;

VOID DriverUnload(PDRIVER_OBJECT pDriver);

typedef NTSTATUS(NTAPI *NTOPENPROCESS)(__out PHANDLE  ProcessHandle,
    __in ACCESS_MASK  DesiredAccess,
    __in POBJECT_ATTRIBUTES  ObjectAttributes,
    __in_opt PCLIENT_ID  ClientId
    );

NTOPENPROCESS g_OldOpenProcess = NULL;

NTSTATUS NTAPI MyNtOpenProcess(__out PHANDLE  ProcessHandle,
    __in ACCESS_MASK  DesiredAccess,
    __in POBJECT_ATTRIBUTES  ObjectAttributes,
    __in_opt PCLIENT_ID  ClientId
)
{
    if ((ULONG)ClientId->UniqueProcess == g_uProtectPID)
    {
        return STATUS_ABANDONED;
    }
    return  g_OldOpenProcess(ProcessHandle, DesiredAccess, ObjectAttributes, ClientId);
}

void InitInfo()
{
    g_uProtectPID = 2772;
    g_OldOpenProcess = (NTOPENPROCESS) KeServiceDescriptorTable.ServiceTableBase[0xBE];

}
void OffProtect()
{
    __asm { //关闭内存保护
        push eax;
        mov eax, cr0;
        and eax, ~0x10000;
        mov cr0, eax;
        pop eax;
    }

}
void OnProtect()
{
    __asm { //恢复内存保护
        push eax;
        mov eax, cr0;
        or eax, 0x10000;
        mov cr0, eax;
        pop eax;
    }

}

void OnHook()
{
    //关掉页保护
    OffProtect();
    KeServiceDescriptorTable.ServiceTableBase[0xBE] = (ULONG)MyNtOpenProcess;
    //开启页保护
    OnProtect();
}

void OffHook()
{
    //关掉页保护
    OffProtect();
    KeServiceDescriptorTable.ServiceTableBase[0xBE] = (ULONG)g_OldOpenProcess;
    //开启页保护
    OnProtect();
}

NTSTATUS DriverEntry(PDRIVER_OBJECT pDriver, PUNICODE_STRING pPath)
{

    UNREFERENCED_PARAMETER(pPath);
    DbgBreakPoint();
    InitInfo();
    OnHook();
    pDriver->DriverUnload = DriverUnload;
    return STATUS_SUCCESS;
}

VOID DriverUnload(PDRIVER_OBJECT pDriver)
{
    OffHook();
    UNREFERENCED_PARAMETER(pDriver);
}