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Windows NT Driver >> Assembly >> IOCTL

IRP

參考資訊：
1. Four-F
2. Source Code

Input Output Control(IOCTL)是另一種可以跟驅動程式溝通的方式，本身帶有命令參數，驅動程式可以依據不一樣的命令做不一樣的事情，而除了命令以外，IOCTL更把Buffer切成Input和Output兩塊，單一次命令的運作就可以完成讀寫的動作，Buffer的屬性也是需要做設定才可以使用，分為Buffered、Direct和Neither這三種設定方式，感覺是不是跟File的Buffer設定方式很相似呢？沒錯，基本上是一樣的，雖然司徒講得有點複雜，不過，只要把Buffer的設定方式搞懂後，使用者就可以發現，整個運作原理是相當容易理解的。

當然，使用者可能好奇，IRP_MJ_READ和IRP_MJ_WRITE是否可以取代IRP_MJ_DEVICE_CONTROL的功能呢？答案：肯定是可以的，只要把資料做編碼，功能上是可以取代的，只是這樣的作法，把控制應用以及大量傳輸的概念都綁在一起，失去原有的設計本質，因此，如果以資料為傳輸目的，建議使用IRP_MJ_READ和IRQP_MJ_WRITE，而以控制應用為目的時，則建議使用IRP_MJ_DEVICE_CONTROL的方式。

至於IOCTL命令到底是什麼東西呢？其實就是一個編碼後的32Bit的數值，欄位如下所示：

#define CTL_CODE(DeviceType, Function, Transfer, Access) (((DeviceType) << 16) | ((Access) << 14) | ((Function) << 2) | (Transfer))

表格如下：

Ref. defining-i-o-control-codes
透過Microsoft的Macro(CTL_CODE)定義該數值，說穿了，只要App跟驅動程式都可以互相知道對方的意思(IOCTL命令)就可以，當然有一些是Microsoft定義保留的Global IOCTL，在使用上，需要特別注意一下。

對應的溝通管道：

Win32 API	Kernel IRP
CreateFile()	IRP_MJ_CREATE
DeviceIoControl()	IRP_MJ_DEVICE_CONTROL
CloseFile()	IRP_MJ_CLOSE

取得方式：

IOCTL Code
(IrpStack) Parameters.DeviceIoControl.IoControlCode

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\include\wxp\wdm.inc
include c:\masm32\Macros\Strings.mac
includelib c:\masm32\lib\wxp\i386\ntoskrnl.lib
  
public DriverEntry
 
IOCTL_TEST equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, 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
SHOW_MSG byte "IOCTL_TEST",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
  IoGetCurrentIrpStackLocation pIrp
  mov eax, (IO_STACK_LOCATION PTR [eax]).Parameters.DeviceIoControl.IoControlCode
  .if eax == IOCTL_TEST
    invoke DbgPrint, offset SHOW_MSG
  .endif

  mov eax, pIrp
  mov (_IRP PTR [eax]).IoStatus.Status, STATUS_SUCCESS
  push 0
  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, 0, 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()僅列印IOCTL_TEST命令。

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_TEST equ CTL_CODE(FILE_DEVICE_UNKNOWN, 800h, METHOD_BUFFERED, FILE_ANY_ACCESS)

.const 
DEV_NAME db "\\.\MyDriver",0

.data?
hFile dd ?
dwRet dd ?

.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, $CTA0("failed to open mydriver")
    invoke ExitProcess, -1
  .endif
  
  mov hFile, eax
  invoke DeviceIoControl, hFile, IOCTL_TEST, NULL, 0, NULL, 0, offset dwRet, NULL
  invoke CloseHandle, hFile
  invoke ExitProcess, 0
end start

結果

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