windows2000中怎么进入ring0》》》》》

Question

windows2000中怎么进入ring0,最好有代码！谢谢！！！

Answer 1

转载：
     Windows NT/2000/XP下不用驱动的Ring0代码实现      
            WebCrazy(http://webcrazy.yeah.net/)     大家知道，Windows NT/2000为实现其可靠性，严格将系统划分为内核模式与用户模式，在i386系统中分别对应CPU的Ring0与Ring3级别。Ring0下，可以执行特权级指令，对任何I/O设备都有访问权等等。要实现从用户态进入核心态，即从Ring 3进入Ring 0必须借助CPU的某种门机制，如中断门、调用门等。而Windows NT/2000提供用户态执行系统服务(Ring 0例程)的此类机制即System Service的int 2eh中断服务等，严格的参数检查，只能严格的执行Windows NT/2000提供的服务，而如果想执行用户提供的Ring 0代码(指运行在Ring 0权限的代码)，常规方法似乎只有编写设备驱动程序。本文将介绍一种在用户态不借助任何驱动程序执行Ring0代码的方法。    Windows NT/2000将设备驱动程序调入内核区域(常见的位于地址0x80000000上)，由DPL为0的GDT项8，即cs为8时实现Ring 0权限。本文通过在系统中构造一个指向我们的代码的调用门(CallGate)，实现Ring0代码。基于这个思路，为实现这个目的主要是构造自己的CallGate。CallGate由系统中叫Global Descriptor Table(GDT)的全局表指定。GDT地址可由i386指令sgdt获得(sgdt不是特权级指令，普通Ring 3程序均可执行)。GDT地址在Windows NT/2000保存于KPCR(Processor Control Region)结构中(见《再谈Windows NT/2000环境切换》)。GDT中的CallGate是如下的格式：    typedef struct
    {
        unsigned short  offset_0_15;
        unsigned short  selector;        unsigned char    param_count : 4;
        unsigned char    some_bits   : 4;        unsigned char    type        : 4;
        unsigned char    app_system  : 1;
        unsigned char    dpl         : 2;
        unsigned char    present     : 1;
    
        unsigned short  offset_16_31;
    } CALLGATE_DESCRIPTOR;    GDT位于内核区域，一般用户态的程序是不可能对这段内存区域有直接的访问权。幸运的是Windows NT/2000提供了一个叫PhysicalMemory的Section内核对象位于\Device的路径下。顾名思义，通过这个Section对象可以对物理内存进行操作。用objdir.exe对这个对象分析如下：    C:\NTDDK\bin>objdir /D \Device    PhysicalMemory                   
        Section
        DACL - 
           Ace[ 0] - Grant - 0xf001f - NT AUTHORITY\SYSTEM
                             Inherit: 
                             Access: 0x001F  and  ( D RCtl WOwn WDacl )           Ace[ 1] - Grant - 0x2000d - BUILTIN\Administrators
                             Inherit: 
                             Access: 0x000D  and  ( RCtl )    从dump出的这个对象DACL的Ace可以看出默认情况下只有SYSTEM用户才有对这个对象的读写权限，即对物理内存有读写能力，而Administrator只有读权限，普通用户根本就没有权限。不过如果我们有Administrator权限就可以通过GetSecurityInfo、SetEntriesInAcl与SetSecurityInfo这些API来修改这个对象的ACE。这也是我提供的代码需要Administrator的原因。实现的代码如下：    VOID SetPhyscialMemorySectionCanBeWrited(HANDLE hSection)
    {       PACL pDacl=NULL;
       PACL pNewDacl=NULL;
       PSECURITY_DESCRIPTOR pSD=NULL;
       DWORD dwRes;
       EXPLICIT_ACCESS ea;       if(dwRes=GetSecurityInfo(hSection,SE_KERNEL_OBJECT,DACL_SECURITY_INFORMATION,
                  NULL,NULL,&pDacl,NULL,&pSD)!=ERROR_SUCCESS)
          {
             printf( "GetSecurityInfo Error %u\n", dwRes );
             goto CleanUp;
          }       ZeroMemory(&ea, sizeof(EXPLICIT_ACCESS));
       ea.grfAccessPermissions = SECTION_MAP_WRITE;
       ea.grfAccessMode = GRANT_ACCESS;
       ea.grfInheritance= NO_INHERITANCE;
       ea.Trustee.TrusteeForm = TRUSTEE_IS_NAME;
       ea.Trustee.TrusteeType = TRUSTEE_IS_USER;
       ea.Trustee.ptstrName = "CURRENT_USER";
       if(dwRes=SetEntriesInAcl(1,&ea,pDacl,&pNewDacl)!=ERROR_SUCCESS)
          {
             printf( "SetEntriesInAcl %u\n", dwRes );
             goto CleanUp;
          }       if(dwRes=SetSecurityInfo(hSection,SE_KERNEL_OBJECT,DACL_SECURITY_INFORMATION,NULL,NULL,pNewDacl,NULL)!=ERROR_SUCCESS)
          {
             printf("SetSecurityInfo %u\n",dwRes);
             goto CleanUp;
          }    CleanUp:       if(pSD)
          LocalFree(pSD);
       if(pNewDacl)
          LocalFree(pSD);
    }

Answer 2

这段代码对给定HANDLE的对象增加了如下的ACE:     PhysicalMemory                   
        Section
        DACL - 
           Ace[ 0] - Grant - 0x2 - WEBCRAZY\Administrator
                             Inherit: 
                             Access: 0x0002    //SECTION_MAP_WRITE    这样我们在有Administrator权限的条件下就有了对物理内存的读写能力。但若要修改GDT表实现Ring 0代码。我们将面临着另一个难题，因为sgdt指令获得的GDT地址是虚拟地址(线性地址)，我们只有知道GDT表的物理地址后才能通过\Device\PhysicalMemory对象修改GDT表，这就牵涉到了线性地址转化成物理地址的问题。我们先来看一看Windows NT/2000是如何实现这个的：    kd> u nt!MmGetPhysicalAddress l 30
    ntoskrnl!MmGetPhysicalAddress:
    801374e0 56               push    esi
    801374e1 8b742408         mov     esi,[esp+0x8]
    801374e5 33d2             xor     edx,edx
    801374e7 81fe00000080     cmp     esi,0x80000000
    801374ed 722c             jb    ntoskrnl!MmGetPhysicalAddress+0x2b (8013751b)
    801374ef 81fe000000a0     cmp     esi,0xa0000000
    801374f5 7324             jnb   ntoskrnl!MmGetPhysicalAddress+0x2b (8013751b)
    801374f7 39153ce71780     cmp     [ntoskrnl!MmKseg2Frame (8017e73c)],edx
    801374fd 741c             jz    ntoskrnl!MmGetPhysicalAddress+0x2b (8013751b)
    801374ff 8bc6             mov     eax,esi
    80137501 c1e80c           shr     eax,0xc
    80137504 25ffff0100       and     eax,0x1ffff
    80137509 6a0c             push    0xc
    8013750b 59               pop     ecx
    8013750c e8d3a7fcff       call    ntoskrnl!_allshl (80101ce4)
    80137511 81e6ff0f0000     and     esi,0xfff
    80137517 03c6             add     eax,esi
    80137519 eb17             jmp   ntoskrnl!MmGetPhysicalAddress+0x57 (80137532)
    8013751b 8bc6             mov     eax,esi
    8013751d c1e80a           shr     eax,0xa
    80137520 25fcff3f00       and     eax,0x3ffffc
    80137525 2d00000040       sub     eax,0x40000000
    8013752a 8b00             mov     eax,[eax]
    8013752c a801             test    al,0x1
    8013752e 7506             jnz   ntoskrnl!MmGetPhysicalAddress+0x44 (80137536)
    80137530 33c0             xor     eax,eax
    80137532 5e               pop     esi
    80137533 c20400           ret     0x4    从这段汇编代码可看出如果线性地址在0x80000000与0xa0000000范围内，只是简单的进行移位操作(位于801374ff-80137519指令间)，并未查页表。我想Microsoft这样安排肯定是出于执行效率的考虑。这也为我们指明了一线曙光，因为GDT表在Windows NT/2000中一般情况下均位于这个区域(我不知道/3GB开关的Windows NT/2000是不是这种情况)。    经过这样的分析，我们就可以只通过用户态程序修改GDT表了。而增加一个CallGate就不是我可以介绍的了，找本Intel手册自己看一看了。具体实现代码如下：    typedef struct gdtr {
        short Limit;
        short BaseLow;
        short BaseHigh;
    } Gdtr_t, *PGdtr_t;    ULONG MiniMmGetPhysicalAddress(ULONG virtualaddress)
    {
        if(virtualaddress<0x80000000||virtualaddress>=0xA0000000)
           return 0;
        return virtualaddress&0x1FFFF000;
    }    BOOL ExecRing0Proc(ULONG Entry,ULONG seglen)
    {
       Gdtr_t gdt;
       __asm sgdt gdt;
     
       ULONG mapAddr=MiniMmGetPhysicalAddress(gdt.BaseHigh<<16U|gdt.BaseLow);
       if(!mapAddr) return 0;       HANDLE   hSection=NULL;
       NTSTATUS status;
       OBJECT_ATTRIBUTES        objectAttributes;
       UNICODE_STRING objName;
       CALLGATE_DESCRIPTOR *cg;       status = STATUS_SUCCESS;
   
       RtlInitUnicodeString(&objName,L"\\Device\\PhysicalMemory");       InitializeObjectAttributes(&objectAttributes,
                                  &objName,
                                  OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,
                                  NULL,
                                 (PSECURITY_DESCRIPTOR) NULL);       status = ZwOpenSection(&hSection,SECTION_MAP_READ|SECTION_MAP_WRITE,&objectAttributes);       if(status == STATUS_ACCESS_DENIED){
          status = ZwOpenSection(&hSection,READ_CONTROL|WRITE_DAC,&objectAttributes);
          SetPhyscialMemorySectionCanBeWrited(hSection);
          ZwClose(hSection);
          status =ZwOpenSection(&hSection,SECTION_MAP_WRITE|SECTION_MAP_WRITE,&objectAttributes);
       }       if(status != STATUS_SUCCESS)
         {
            printf("Error Open PhysicalMemory Section Object,Status:%08X\n",status);
            return 0;
         }
      
       PVOID BaseAddress;       BaseAddress=MapViewOfFile(hSection,
                     FILE_MAP_READ|FILE_MAP_WRITE,
                     0,
                     mapAddr,    //low part
                     (gdt.Limit+1));       if(!BaseAddress)
          {
             printf("Error MapViewOfFile:");
             PrintWin32Error(GetLastError());
             return 0;
          }       BOOL setcg=FALSE;       for(cg=(CALLGATE_DESCRIPTOR *)((ULONG)BaseAddress+(gdt.Limit&0xFFF8));(ULONG)cg>(ULONG)BaseAddress;cg--)
           if(cg->type == 0){
             cg->offset_0_15 = LOWORD(Entry);
             cg->selector = 8;
             cg->param_count = 0;
             cg->some_bits = 0;
             cg->type = 0xC;          // 386 call gate
             cg->app_system = 0;      // A system descriptor
             cg->dpl = 3;             // Ring 3 code can call
             cg->present = 1;
             cg->offset_16_31 = HIWORD(Entry);
             setcg=TRUE;
             break;
          }       if(!setcg){
            ZwClose(hSection);
            return 0;
       }       short farcall[3];       farcall[2]=((short)((ULONG)cg-(ULONG)BaseAddress))|3;  //Ring 3 callgate;       if(!VirtualLock((PVOID)Entry,seglen))
          {
             printf("Error VirtualLock:");
             PrintWin32Error(GetLastError());
             return 0;
          }       SetThreadPriority(GetCurrentThread(),THREAD_PRIORITY_TIME_CRITICAL);       Sleep(0);       _asm call fword ptr [farcall]       SetThreadPriority(GetCurrentThread(),THREAD_PRIORITY_NORMAL);       VirtualUnlock((PVOID)Entry,seglen);       //Clear callgate
       *(ULONG *)cg=0;
       *((ULONG *)cg+1)=0;       ZwClose(hSection);
       return TRUE;    }