Re: secdir review of draft-ietf-mpls-rfc6374-udp-return-path

Stewart Bryant <stewart.bryant@gmail.com> Thu, 07 April 2016 14:16 UTC

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Subject: Re: secdir review of draft-ietf-mpls-rfc6374-udp-return-path
To: Sandra Murphy <sandy@tislabs.com>, secdir@ietf.org, The IETF <ietf@ietf.org>, draft-ietf-mpls-rfc6374-udp-return-path.all@tools.ietf.org
References: <07A977A4-FD9E-4669-A8D0-7644131E06AD@tislabs.com> <5673D89F.7090409@gmail.com>
From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Thu, 7 Apr 2016 15:16:16 +0100
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On 18/12/2015 09:57, Stewart Bryant wrote:

Sandy, I have looked at this discussion again. Please see inline:
>
>>
>> Section 4.2
>>
>>
>>   If an Out-of-band response is requested and the Address object or the
>>   URO is missing, the query SHOULD be dropped in the case of a
>>   unidirectional LSP.  If both these TLVs are missing on a
>>   bidirectional LSP, the control code of Response message should set to
>>   0x1C indicating "Error - Invalid Message" ([RFC6374] Section 3.1) and
>>   the response SHOULD be sent over the reverse LSP.  The receipt of
>>   such a mal-formed request SHOULD be notified to the operator through
>>   the management system, taking the normal precautions with respect to
>>   the prevention of overload of the error reporting system.
>>
>> The first sentence says that both the Address object and the URO must
>> be present or the query is dropped - right?  I'm reading this as
>>
>>       (if not(Address) OR not(URO)) then drop.
>>
>> What Address object - there are three - Return, Source and
>> Destination.  I'm betting on Return, but the text should be clear.
>
> That is return address - I will update the text.

Looking at the text again, since we are ONLY talking about systems using 
the
URO, the Address object text fragment is pointless so I have deleted it.

>
>
>>
>> The RFC6374 out-of-band response feature and the "Return Address"
>> object seem to indicate the potential exists in RFC6374 as well.
>> RFC6374's security consideration section does not mention the
>> reflection attack possibility, only the integrity of the return
>> out-of-band path and the possibility of affecting the validity of the
>> measurements.  But even if the assumptions of well-managed, private,
>> service provider networks are met, I believe that the potential and
>> increased need for careful configuration should be mentioned. "Note:
>> the feature can be misused, so take care".  Perhaps a manageability
>> section caution about checking the Return Address or URO to ensure
>> addresses are within the private or service provider network.
>> something?  Or presume all will be well, because this is to be used in
>> well managed private and service provider networks?
> I will look at adding some text, although the assumption is that
> MPLS networks are well managed, and there are many other ways
> they would break if they were not.
>

This text is only about the URO case. The only residual text on the DA obj
is in the section that is to be deleted.

- Stewart