Windows NT Driver >> Assembly >> File
DO_BUFFERED_IO
參考資訊:
1. Four-F
2. Source Code
DO_BUFFERED_IO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,DO_BUFFERED_IO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:
IRP | Buffer | Length |
---|---|---|
IRP_MJ_READ | (Irp) AssociatedIrp.SystemBuffer |
(IrpStack) Parameters.Read.Length |
IRP_MJ_WRITE | (Irp) AssociatedIrp.SystemBuffer |
(IrpStack) Parameters.Write.Length |
在做Driver的檔案操作時,其讀寫是順序性的,除非Driver使用Pending IRP的處理手法,不然,不需擔心指標複寫錯誤的問題。
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 pNextDevice PDEVICE_OBJECT ? szBuffer byte 255 dup(?) OurDeviceExtension ends .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 .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 IrpReadWrite proc uses ebx pOurDevice:PDEVICE_OBJECT, pIrp:PIRP local pBuf:dword local dwLen:dword local pdx:PTR OurDeviceExtension and dwLen, 0 mov eax, pOurDevice push (DEVICE_OBJECT PTR [eax]).DeviceExtension pop pdx IoGetCurrentIrpStackLocation pIrp movzx eax, (IO_STACK_LOCATION PTR [eax]).MajorFunction .if eax == IRP_MJ_WRITE invoke DbgPrint, $CTA0("IRP_MJ_WRITE") IoGetCurrentIrpStackLocation pIrp push (IO_STACK_LOCATION PTR [eax]).Parameters.Write._Length pop dwLen mov eax, pIrp push (_IRP PTR [eax]).AssociatedIrp.SystemBuffer pop pBuf invoke DbgPrint, $CTA0("Buffer: %s, Length: %d"), pBuf, dwLen mov eax, pdx mov ebx, pBuf invoke memcpy, addr (OurDeviceExtension PTR [eax]).szBuffer, ebx, dwLen .elseif eax == IRP_MJ_READ invoke DbgPrint, $CTA0("IRP_MJ_READ") mov eax, pIrp push (_IRP PTR [eax]).AssociatedIrp.SystemBuffer pop pBuf mov eax, pOurDevice push (DEVICE_OBJECT PTR [eax]).DeviceExtension pop pdx mov eax, pdx mov ebx, pBuf invoke strcpy, ebx, addr (OurDeviceExtension PTR [eax]).szBuffer mov eax, pdx invoke strlen, addr (OurDeviceExtension PTR [eax]).szBuffer inc eax push eax pop dwLen .endif mov eax, pIrp push dwLen pop (_IRP PTR [eax]).IoStatus.Information mov (_IRP PTR [eax]).IoStatus.Status, STATUS_SUCCESS fastcall IofCompleteRequest, pIrp, IO_NO_INCREMENT mov eax, STATUS_SUCCESS ret IrpReadWrite 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_WRITE * (sizeof PVOID)], offset IrpReadWrite mov (DRIVER_OBJECT PTR [eax]).MajorFunction[IRP_MJ_READ * (sizeof PVOID)], offset IrpReadWrite 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
IrpFile()收到IRP_MJ_WRITE時,Driver複製User Buffer的內容到szBuffer,而收到IRP_MJ_READ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ReadFile()或WriteFile()完成的長度。
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 includelib c:\masm32\lib\user32.lib includelib c:\masm32\lib\masm32.lib includelib c:\masm32\lib\msvcrt.lib includelib c:\masm32\lib\kernel32.lib .const DEV_NAME db "\\.\MyDriver",0 MSG_ERR db "failed to open mydriver",0 MSG_SEND db "I am error",0 MSG_WR db "WR: %s, %d",10,13,0 MSG_RD db "RD: %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 StrLen, offset MSG_SEND inc eax mov dwRet, eax invoke crt_printf, offset MSG_WR, offset MSG_SEND, dwRet invoke WriteFile, hFile, offset MSG_SEND, dwRet, offset dwRet, 0 invoke crt_memset, offset szBuffer, 0, 255 invoke ReadFile, hFile, offset szBuffer, 255, offset dwRet, 0 invoke crt_printf, offset MSG_RD, offset szBuffer, dwRet invoke CloseHandle, hFile invoke ExitProcess, 0 end start
結果