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

Tue Mar 1 21:30:04 UTC 2016

Bryan,
Thanks for all the info and all the legwork in testing this.
Uri.
On 03/01/2016 10:41 PM, Bryan Burgin wrote:
> 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.
>>>
>>