[cifs-protocol] FSCTL_SRV_COPYCHUNK error response

[David Disseldorp]

Hi DocHelp,

[MS-SMB2] currently describes the response to a FSCTL_SRV_COPYCHUNK SMB2
ioctl request with the following:

  3.3.4.4 Sending an Error Response

  When the server is responding with a failure to any command sent by
  the client, the response message MUST be constructed as described
  here. An error code other than one of the following indicates a
  failure:
...
  - Any status other than STATUS_SUCCESS in a FSCTL_SRV_COPYCHUNK or
    FSCTL_SRV_COPYCHUNK_WRITE Response, when returning an
    SRV_COPYCHUNK_RESPONSE as described in section 2.2.32.1.
...
  Following the SMB2 header MUST be an SMB2 ERROR Response structure, as
  specified in section 2.2.2.


  2.2.32.1 SRV_COPYCHUNK_RESPONSE

  ChunksWritten (4 bytes): If the Status field in the SMB2 header of the
  response is not STATUS_INVALID_PARAMETER, as specified in [MS-ERREF]
  section 2.3, this value indicates the number of chunks that were
  successfully written. If the Status field in the SMB2 header of
  the response is STATUS_INVALID_PARAMETER, this value indicates the
  maximum number of chunks that the server will accept in a single
  request. This would allow the client to correctly reissue the request.

...

I interpret the above text as meaning that the response to a
FSCTL_SRV_COPYCHUNK SMB2 ioctl request will not include an SMB2 Error
Response structure. Instead, a SRV_COPYCHUNK_RESPONSE structure will
be returned, either with the request maximums (in the case of
STATUS_INVALID_PARAMETER), or the amount successfully written.

Testing against Windows Server 2012 does not back up my interpretation.
Issuing a FSCTL_SRV_COPYCHUNK SMB2 ioctl request with an invalid
SourceKey field sees the server respond with an Error Response and
STATUS_OBJECT_NAME_NOT_FOUND.

Have I misinterpreted the documentation, or would it make sense to
change 3.3.4.4?
An error code other than one of the following indicates a failure:
- A status of STATUS_INVALID_PARAMETER in a FSCTL_SRV_COPYCHUNK or
  FSCTL_SRV_COPYCHUNK_WRITE Response...

Regards, David