[cifs-protocol] SMB2 mixed lock & unlock requests in a single SMB_LOCK request

[Sebastian Canevari]

Hi Steven,

Thank you for your email.

Someone from my team will be working with you and will be contacting you tomorrow.

Thanks and regards,



Sebastian Canevari
Senior Support Escalation Engineer, US-CSS DSC PROTOCOL TEAM
7100 N Hwy 161, Irving, TX - 75039
"Las Colinas - LC2"
Tel: +1 469 775 7849
e-mail: sebastc at microsoft.com<mailto:sebastc at microsoft.com>

From: Steven Danneman [mailto:steven.danneman at isilon.com]
Sent: Monday, November 30, 2009 5:58 PM
To: Interoperability Documentation Help; cifs-protocol at samba.org; pfif at tridgell.net
Subject: SMB2 mixed lock & unlock requests in a single SMB_LOCK request

Hello,

I've come across another SMB2 locking issue that I can't find explicit documentation for in MS-SMB2 (v18.0).

My first question, is whether a single SMB_LOCK request can contain both unlock and lock requests as the LockingAndX command type in SMBv1 could?  The MS-SMB2 document hints that the answer to this question is "no" but it doesn't seem to explicitly state it anywhere.

Section 2.2.26 states: "The SMB2 LOCK Request packet is sent by the client to either lock or unlock portions of a file."

This statement is ambiguous as to whether the "or" is inclusive or exclusive.

In my testing, sending both lock and unlock requests in a single SMB2 locking request returns a STATUS_INVALID_PARAMETER.  However, if the requests are ordered such that a unlock structure come first, the unlock request seems to succeed.

The attached pcap, against W2K8R2 shows:

1) Packet 27-28:  A single lock request succeeding on range 0-10.
2) Packet 29-30:  A lock request with unlock(0-10) and lock(10-10) failing with INVALID_PARAMETER.
3) Packet 31-32:  A lock request with lock(0-10) and lock(10-10) succeeding, showing that the previous request, though it returned an error, succeeded in unlocking.

It seems to me the server behavior should be to return STATUS_INVALID_PARAMETER without completing any of the lock/unlock requests when they are mixed.  Both the fact that this isn't allowed, and the W2K8R2 behavior deviation should be documented.

Thanks,

Steven Danneman | Software Development Engineer
Isilon Systems    P +1-206-315-7500     F  +1-206-315-7501
www.isilon.com<http://www.isilon.com>

[cid:image001.gif at 01C81005.1792D9C0]   How breakthroughs begin. (tm)

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