[cifs-protocol] [REG:116022413751567 ] Response to SVHDX_OPEN_DEVICE_CONTEXT[_V2] when shared VHDX is not supported

Tue Mar 1 20:41:24 UTC 2016

Thank you for being patient.
You should ignore this context in this scenario where you don't support RSVD.
We are discussing internally exactly how we propose to change the specification as this may drive changes in both [MS-SMB2] and [MS-RSVD].  But the outcome remains that you should ignore it and continue processing the Create (including not including the RSVD Create Context in the reply).
Thank you for raising this issue.
Bryan 

-----Original Message-----
From: Bryan Burgin 
Sent: Friday, February 26, 2016 10:32 AM
To: 'Jeremy Allison' <jra at samba.org>
Cc: Uri Simchoni <uri at samba.org>; cifs-protocol at lists.samba.org; MSSolve Case Email <casemail at microsoft.com>
Subject: RE: [cifs-protocol] [REG:116022413751567 ] Response to SVHDX_OPEN_DEVICE_CONTEXT[_V2] when shared VHDX is not supported

I set up two Windows 10 (10586) machines and did Windows backup:

                wbadmin start backup -allCritical -backupTarget:\\10.0.0.103\share -user:workgroup\bburgin -password:P at ssw0rd

I note the Create has a VHDX V2 Open Context: [MS-RSVD] 2.2.4.32 "SVHDX_OPEN_DEVICE_CONTEXT_V2 Structure"
The response does NOT include [MS-RSVD] 2.2.4.33 "SVHDX_OPEN_DEVICE_CONTEXT_V2_RESPONSE Structure"

I'm looking into why that is.

Let's hold off acting on anything until the investigation is complete.

B.

-----Original Message-----
From: Jeremy Allison [mailto:jra at samba.org]
Sent: Friday, February 26, 2016 10:19 AM
To: Bryan Burgin <bburgin at microsoft.com>
Cc: Uri Simchoni <uri at samba.org>; cifs-protocol at lists.samba.org; MSSolve Case Email <casemail at microsoft.com>; jra at samba.org
Subject: Re: [cifs-protocol] [REG:116022413751567 ] Response to SVHDX_OPEN_DEVICE_CONTEXT[_V2] when shared VHDX is not supported

On Fri, Feb 26, 2016 at 06:16:25PM +0000, Bryan Burgin wrote:
> I'm still researching this on my end.
> B.

OK, it does look like we jumped the gun on removing the STATUS_INVALID_PARAMETER check (but right now this is only in master).

I'll wait until you report back before we revert, just in case you can find us a "get-out-of-jail-free" card somewhere in your research :-).

Cheers,

	Jeremy.

> -----Original Message-----
> From: Uri Simchoni [mailto:uri at samba.org]
> Sent: Thursday, February 25, 2016 8:51 PM
> To: Bryan Burgin <bburgin at microsoft.com>; Jeremy Allison 
> <jra at samba.org>
> Cc: cifs-protocol at lists.samba.org; MSSolve Case Email 
> <casemail at microsoft.com>
> Subject: Re: [cifs-protocol] [REG:116022413751567 ] Response to 
> SVHDX_OPEN_DEVICE_CONTEXT[_V2] when shared VHDX is not supported
> 
> On 02/26/2016 12:02 AM, Bryan Burgin wrote:
> > The errata only concerns processing for create context names that are unknown (like 'AAPL').  [MS-SMB2] 2.2.13.2 "SMB2_CREATE_CONTEXT Request Values" enumerates the known context names and identifies 0x9CCBCF9E04C1E643980E158DA1F6EC83 as SVHDX_OPEN_DEVICE_CONTEXT.  [MS-SMB2] further has the server processing rule for at 3.3.5.9.14 "Handling the SVHDX_OPEN_DEVICE_CONTEXT Create Context" that describe "If IsSharedVHDSupported is FALSE, the server MUST fail the request with STATUS_INVALID_DEVICE_REQUEST" for "servers that implement the SMB 3.0.2 or SMB 3.1.1 dialect".
> >
> That's also my reading of the errata+spec, which is why I opened this case (i.e. I agree that ignoring the SVHDX is not according to the spec and I was hoping the spec is wrong).
> 
> One missing piece for me is what a Windows server does - does it always support RSVD by definition or is it configuration-dependent (because it needs a SCSI backend to which it tunnels the SCSI commands). And if it's configuration-dependent, how the system behaves when there's no RSVD.
> 
> 
> > B.
> >
> > -----Original Message-----
> > From: Jeremy Allison [mailto:jra at samba.org]
> > Sent: Thursday, February 25, 2016 1:50 PM
> > To: Bryan Burgin <bburgin at microsoft.com>
> > Cc: Uri Simchoni <uri at samba.org>; cifs-protocol at lists.samba.org; 
> > MSSolve Case Email <casemail at microsoft.com>
> > Subject: Re: [cifs-protocol] [REG:116022413751567 ] Response to 
> > SVHDX_OPEN_DEVICE_CONTEXT[_V2] when shared VHDX is not supported
> >
> > On Thu, Feb 25, 2016 at 08:54:56PM +0000, Bryan Burgin wrote:
> >
> >> However, per the spec, we believe that you should be either 
> >> supporting the context (and RSVD) or failing the Create.
> >
> > Hang on, the errata now says:
> >
> > https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fmsdn.
> > microsoft.com%2fen-us%2flibrary%2fdn785067.aspx&data=01%7c01%7cbburg
> > in
> > %40microsoft.com%7cb2eeec7298884d083d0f08d33e2dab75%7c72f988bf86f141
> > af
> > 91ab2d7cd011db47%7c1&sdata=E3QLM1S5A2aVW18YKIxi8QfA%2fwuHVdSzW1dsByb
> > NQ
> > tg%3d
> >
> > 2015/12/11
> > In section 3.3.5.9 Receiving an SMB2 CREATE Request, the first paragraph under Create Context Validation has been changed.
> > Changed from:
> > The server SHOULD<247> fail any request having a create context not specified in section 2.2.13.2 with a STATUS_INVALID_PARAMETER error.
> > <247> Section 3.3.5.9: Windows Vista SP1, Windows Server 2008, Windows 7, Windows Server 2008 R2, Windows 8, and Windows Server 2012 ignore create contexts having a NameLength greater than 4 and ignore create contexts with a length of 4 that are not specified in section 2.2.13.2.
> > Changed to:
> > The server MUST fail create contexts having a NameLength less than 4 with a STATUS_INVALID_PARAMETER error.
> >
> > That doesn't say anything about supporting a specific context - just return STATUS_INVALID_PARAMETER if NameLength < 4 - which we already do.
> >
> > As far as I can see we are correctly implementing the spec.
> >
> > Jeremy.
> >
> 