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Windows NT Driver >> Assembly >> IOCTL

METHOD_BUFFERED

參考資訊：
1. Four-F
2. Source Code

METHOD_BUFFERED的處理手法就是I/O Manager會在Kernel配置一塊跟User Buffer一樣大小的記憶體，Driver只能對該配置的記憶體做讀寫的操作，而讀寫的操作都會同步回User Buffer，也因為結果都需要整塊複製回User Buffer，因此，METHOD_BUFFERED的方式會消耗比較大的資源，速度也比較慢。

參考如下微軟的圖表說明(IRP_MJ_READ)：

記憶體指標：

	Buffer	Length
Input	(Irp) AssociatedIrp.SystemBuffer	(IrpStack) Parameters.DeviceIoControl.InputBufferLength
Output	(Irp) AssociatedIrp.SystemBuffer	(IrpStack) Parameters.DeviceIoControl.OutputBufferLength

main.asm

.386p
.model flat, stdcall
option casemap:none
 
include c:\masm32\include\w2k\ntstatus.inc
include c:\masm32\include\w2k\ntddk.inc
include c:\masm32\include\w2k\ntoskrnl.inc
include c:\masm32\include\w2k\ntddkbd.inc
include c:\masm32\Macros\Strings.mac
includelib c:\masm32\lib\wxp\i386\ntoskrnl.lib
  
public DriverEntry
 
OurDeviceExtension struct
  pNextDev PDEVICE_OBJECT ?
  szBuffer byte 255 dup(?)
OurDeviceExtension ends

IOCTL_GET equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, METHOD_BUFFERED, FILE_ANY_ACCESS)
IOCTL_SET equ CTL_CODE(FILE_DEVICE_UNKNOWN, 801h, METHOD_BUFFERED, FILE_ANY_ACCESS)
 
.const
DEV_NAME word "\","D","e","v","i","c","e","\","M","y","D","r","i","v","e","r",0
SYM_NAME word "\","D","o","s","D","e","v","i","c","e","s","\","M","y","D","r","i","v","e","r",0
MSG_GET  byte "IOCTL_GET",0
MSG_SET  byte "IOCTL_SET",0

.code
IrpOpenClose proc pOurDevice:PDEVICE_OBJECT, pIrp:PIRP
  IoGetCurrentIrpStackLocation pIrp
  movzx eax, (IO_STACK_LOCATION PTR [eax]).MajorFunction
  .if eax == IRP_MJ_CREATE
    invoke DbgPrint, $CTA0("IRP_MJ_CREATE")
  .elseif eax == IRP_MJ_CLOSE
    invoke DbgPrint, $CTA0("IRP_MJ_CLOSE")
  .endif

  mov eax, pIrp
  and (_IRP PTR [eax]).IoStatus.Information, 0
  mov (_IRP PTR [eax]).IoStatus.Status, STATUS_SUCCESS
  fastcall IofCompleteRequest, pIrp, IO_NO_INCREMENT
  mov eax, STATUS_SUCCESS
  ret
IrpOpenClose endp

IrpIOCTL proc pOurDevice:PDEVICE_OBJECT, pIrp:PIRP
  local dwLen: DWORD
  local pdx:PTR OurDeviceExtension
  local pBuf:DWORD

  and dwLen, 0
  mov eax, pOurDevice
  push (DEVICE_OBJECT PTR [eax]).DeviceExtension
  pop pdx

  IoGetCurrentIrpStackLocation pIrp
  mov eax, (IO_STACK_LOCATION PTR [eax]).Parameters.DeviceIoControl.IoControlCode
  .if eax == IOCTL_GET
    invoke DbgPrint, offset MSG_GET
    mov eax, pIrp
    push (_IRP PTR [eax]).AssociatedIrp.SystemBuffer
    pop pBuf

    mov eax, pdx
    invoke strcpy, pBuf, addr (OurDeviceExtension PTR [eax]).szBuffer
    
    mov eax, pdx
    invoke strlen, addr (OurDeviceExtension PTR [eax]).szBuffer
    inc eax
    push eax
    pop dwLen
  .elseif eax == IOCTL_SET
    invoke DbgPrint, offset MSG_SET

    IoGetCurrentIrpStackLocation pIrp
    push (IO_STACK_LOCATION PTR [eax]).Parameters.DeviceIoControl.InputBufferLength 
    pop dwLen

    mov eax, pIrp
    push (_IRP PTR [eax]).AssociatedIrp.SystemBuffer
    pop pBuf

    mov eax, pdx
    invoke memcpy, addr (OurDeviceExtension PTR [eax]).szBuffer, pBuf, dwLen
    invoke DbgPrint, $CTA0("Buffer: %s, Length: %d"), pBuf, dwLen
  .endif

  mov eax, pIrp
  mov (_IRP PTR [eax]).IoStatus.Status, STATUS_SUCCESS
  push dwLen
  pop (_IRP PTR [eax]).IoStatus.Information 
  fastcall IofCompleteRequest, pIrp, IO_NO_INCREMENT
  mov eax, STATUS_SUCCESS
  ret
IrpIOCTL endp

Unload proc pOurDriver:PDRIVER_OBJECT
  local szSymName:UNICODE_STRING
        
  invoke RtlInitUnicodeString, addr szSymName, offset SYM_NAME
  invoke IoDeleteSymbolicLink, addr szSymName
        
  mov eax, pOurDriver
  invoke IoDeleteDevice, (DRIVER_OBJECT PTR [eax]).DeviceObject
  ret
Unload endp
 
DriverEntry proc pOurDriver:PDRIVER_OBJECT, pOurRegistry:PUNICODE_STRING
  local pOurDevice:PDEVICE_OBJECT
  local suDevName:UNICODE_STRING
  local szSymName:UNICODE_STRING
   
  mov eax, pOurDriver
  mov (DRIVER_OBJECT PTR [eax]).MajorFunction[IRP_MJ_CREATE * (sizeof PVOID)], offset IrpOpenClose
  mov (DRIVER_OBJECT PTR [eax]).MajorFunction[IRP_MJ_CLOSE  * (sizeof PVOID)], offset IrpOpenClose
  mov (DRIVER_OBJECT PTR [eax]).MajorFunction[IRP_MJ_DEVICE_CONTROL * (sizeof PVOID)], offset IrpIOCTL
  mov (DRIVER_OBJECT PTR [eax]).DriverUnload, offset Unload
   
  invoke RtlInitUnicodeString, addr suDevName, offset DEV_NAME
  invoke RtlInitUnicodeString, addr szSymName, offset SYM_NAME
  invoke IoCreateDevice, pOurDriver, sizeof OurDeviceExtension, addr suDevName, FILE_DEVICE_UNKNOWN, 0, FALSE, addr pOurDevice
  .if eax == STATUS_SUCCESS
    mov eax, pOurDevice
    or (DEVICE_OBJECT PTR [eax]).Flags, DO_BUFFERED_IO
    and (DEVICE_OBJECT PTR [eax]).Flags, not DO_DEVICE_INITIALIZING
    invoke IoCreateSymbolicLink, addr szSymName, addr suDevName
  .endif
  ret
DriverEntry endp
end DriverEntry
.end

IrpIOCTL()收到IOCTL_SET時，Driver複製User Buffer的內容到szBuffer，而收到IOCTL_GET時，將szBuffer內容又複製回User Buffer，完成暫存的功能，IoStatus.Information的數值就是OutBufferSize回傳的長度。

app.asm

.386p
.model flat, stdcall
option casemap:none

include c:\masm32\include\windows.inc
include c:\masm32\include\masm32.inc
include c:\masm32\include\user32.inc
include c:\masm32\include\msvcrt.inc
include c:\masm32\include\kernel32.inc
include c:\masm32\include\w2k\ntddkbd.inc
include c:\masm32\Macros\Strings.mac
 
includelib c:\masm32\lib\user32.lib
includelib c:\masm32\lib\masm32.lib
includelib c:\masm32\lib\msvcrt.lib
includelib c:\masm32\lib\kernel32.lib

IOCTL_GET equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, METHOD_BUFFERED, FILE_ANY_ACCESS)
IOCTL_SET equ CTL_CODE(FILE_DEVICE_UNKNOWN, 801h, METHOD_BUFFERED, FILE_ANY_ACCESS)

.const 
DEV_NAME db "\\.\MyDriver",0
MSG_ERR  db "failed to open mydriver",0
MSG_SEND db "I am error",0
MSG_WR   db "SET: %s, %d",10,13,0
MSG_RD   db "GET: %s, %d",10,13,0

.data?
hFile    dd ?
dwRet    dd ?
szBuffer db 255 dup(?)

.code
start:
  invoke CreateFile, offset DEV_NAME, GENERIC_READ or GENERIC_WRITE, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0
  .if eax == INVALID_HANDLE_VALUE
    invoke crt_printf, offset MSG_ERR
    invoke ExitProcess, -1
  .endif
  
  mov hFile, eax
  invoke crt_memset, offset szBuffer, 0, 255
  invoke StrLen, offset MSG_SEND
  inc eax
  mov dwRet, eax
  invoke crt_printf, offset MSG_WR, offset MSG_SEND, dwRet
  invoke DeviceIoControl, hFile, IOCTL_SET, offset MSG_SEND, dwRet, NULL, 0, offset dwRet, NULL
  
  push 0
  pop dwRet
  invoke DeviceIoControl, hFile, IOCTL_GET, NULL, 0, offset szBuffer, 255, offset dwRet, NULL
  invoke crt_printf, offset MSG_RD, offset szBuffer, dwRet
  invoke CloseHandle, hFile
  invoke ExitProcess, 0
end start

結果

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