Re: iSCSI: use of Text/Login with no data segment

[Martins Krikis <mkrikis@yahoo.com>]

--- Julian Satran <Julian_Satran@il.ibm.com> wrote:

> On a second though the following text may be more
> appropriate:
> 
> A target or initiator MUST NOT use a Text/Login
> Response or Text/
> Login Request with no data segment
> (DataSegmentLength 0) unless explicitly 
> required by a general or a key-specific negotiation
> rule.

I think the words are unnecessarily strong and
disallow such nice guestures as "please, you
speak first" from the iSCSI nodes...

> As it cover all the cases in which we  wanted to
> avoid abuse.

IMHO, you cannot really cover all abuse cases.
What you have achieved is that the "abuser"
(the guy, who says, "please, you first") now
has to be a little more sophisticated, and instead
of sending an empty data segment send the following:
X-vendor_addr-you_speak_first-bogus_key_nr_x=yes.
Whatever the response to this particular key is
irrelevant, of course. But it achieved approximately
the same effect as an empty PDU, and it can be used
to abuse the negotiation process.

This said, I don't think that the potential for
abuse can be helped, nor do I think it is necessary
to try to prevent all abuse. That's why I think
this new wording was unnecessary, but it isn't 
really worth fighting over either.

Martins Krikis, Intel Corp.

Disclaimer: these are my own opinions and
            may not be my employer's.


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