Subject: [tsvwg] Kathleen Moriarty's No Objection on draft-ietf-tsvwg-sctp-ndata-12: (with COMMENT)

From: Kathleen Moriarty <[email-masked]>
Date: Wed, 30 Aug 2017 13:54:54 -0700

Kathleen Moriarty has entered the following ballot position for
draft-ietf-tsvwg-sctp-ndata-12: No Objection

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COMMENT:
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I looked at the references for security considerations, [RFC4960] and
[RFC6458], and don't see an explicit mention of fragmentation overlap and in my
skim, didn't see that it was covered for reassembly as a warning.  Does this
need to be added?  If not, can you explain how it is covered?

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From: Michael Tuexen <[email-masked]>
Date: Thu, 31 Aug 2017 10:01:15 +0200

> On 30. Aug 2017, at 22:54, Kathleen Moriarty <[email-masked]> wrote:
> 
Hi Kathleen,

the fragments don't use a byte range which could overlap, but a sequence
numbers. So if the peer doesn't violate the protocol specification, there
can not be any overlap. If the peer does not follow the specification,
it could try to send different I-DATA chunks (using different TSNs) but
with the same SID, U bit and FSN. A receiver can detect this. In the
FreeBSD implementation we ABORT the association in this case indicating
a Protocol Violation. An alternative would be to just drop the first
(in case it is not partially delivered yet) or drop the second I-DATA
chunk. I guess this is implementation dependent. We had already in RFC 4960
the situation that we have no specified the various ways on inconsistent
parameter combinations and how to deal with them.

Does this clarify this issue? 

Best regards
Michael

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From: Kathleen Moriarty <[email-masked]>
Date: Thu, 31 Aug 2017 07:19:28 -0400

Sent from my iPhone

> Does this clarify this issue? 

Yes, thank you.
Kathleen