[secdir] secdir review of draft-ietf-tsvwg-sctp-prpolicies-05

Joseph Salowey <joe@salowey.net> Mon, 01 December 2014 18:39 UTC

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Date: Mon, 1 Dec 2014 10:39:22 -0800
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From: Joseph Salowey <joe@salowey.net>
To: secdir@ietf.org, draft-ietf-tsvwg-sctp-prpolicies.all@tools.ietf.org, iesg@ietf.org
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Subject: [secdir] secdir review of draft-ietf-tsvwg-sctp-prpolicies-05
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I have reviewed this document as part of the security directorate's ongoing
effort to review all IETF documents being processed by the IESG. These
comments were written primarily for the benefit of the security area
directors. Document editors and WG chairs should treat these comments just
like any other last call comments.

I have reviewed this document and believe it is Ready with minor issues.

This document describes new policies for the users of the SCTP Partial
Reliability service (SCTP-PR).  These policies cover discarding data after
too many retransmissions and discarding lower priority data.

The security considerations are a bit thin.  They mostly refer to RFC 3758
which is also a bit thin and was published before SCTP-DTLS was available.
There is some useful text in RFC 6083 (SCTP-DTLS) :

  "If PR-SCTP as defined in [RFC3758
<https://tools.ietf.org/html/rfc3758>] is used, FORWARD-TSN chunks
MUST
   also be sent in an authenticated way as described in [RFC4895
<https://tools.ietf.org/html/rfc4895>].  This
   makes sure that it is not possible for an attacker to drop messages
   and use forged FORWARD-TSN, SACK, and/or SHUTDOWN chunks to hide this
   dropping."


I think it would be good to include similar text in this document since it
is relevant.  Are there any problems introduced if the INIT or the INIT-ACK
messages are not protected?

Cheers,

Joe