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Date:   Wed, 4 May 2022 16:18:22 -0400
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Subject: Re: CIFS regression mounting vers=1.0 NTLMSSP when hostname is too
 long
Content-Language: en-US
To:     Paulo Alcantara <pc@cjr.nz>, Steven French <sfrench@samba.org>,
        Byron Stanoszek <gandalf@winds.org>
Cc:     linux-cifs@vger.kernel.org, linux-kernel@vger.kernel.org
References: <e6837098-15d9-acb6-7e34-1923cf8c6fe1@winds.org>
 <878rri2i6o.fsf@cjr.nz> <7dc6c729-73cd-74be-eec7-ac4a0013f60f@samba.org>
 <87tua51550.fsf@cjr.nz>
From:   Tom Talpey <tom@talpey.com>
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On 5/4/2022 3:15 PM, Paulo Alcantara wrote:
> Hi Steve,
> 
> Steven French <sfrench@samba.org> writes:
> 
>> makes sense - do you see anything related in the NTLMSSP doc?
> 
> I'll quote some relevant parts from MS-NLMP which make sense to me:
> 
> 	3.1.5.1.2 Client Receives a CHALLENGE_MESSAGE from the Server
> 	...
> 	If the NTLMSSP_NEGOTIATE_VERSION flag is set by the client application,
> 	the Version field MUST be set to the current version (section 2.2.2.10),
> 	and the Workstation field MUST be set to NbMachineName.
> 	
> 	3.2.1.1 Variables Internal to the Protocol
> 	...
> 	NbMachineName: A string that indicates the NetBIOS machine name of the
> 	server.
> 	
> 	2.2.2.1 AV_PAIR
> 	...
> 	MsvAvNbComputerName: The server's NetBIOS computer name. The name MUST
> 	be in Unicode, and is not null-terminated. This type of information MUST
> 	be present in the AV_pair list.
> 
> and indeed we set NTLMSSP_NEGOTIATE_VERSION in
> fs/cifs/sess.c:build_ntlmssp_smb3_negotiate_blob().
> 
> Unless I didn't miss anything obvious, I think we should be sending
> NetBIOS name or simply truncate utsname()->nodename to 16 bytes as
> previously proposed by Byron regardless what protocol version is being
> used.
> 
> Tom, what is your opinion on that?

I think the most conservative and spec-compliant choice should be made.
SMB1 should not be pushing the envelope of interoperability, in this day
and age.

I believe the NetBIOS name is a fixed array of 16 octets, right? So, if
the nodename is shorter, it needs to be padded with 0's.

Did this code change recently? Why???

Tom.