Re: [Dime] AD review of draft-ietf-dime-drmp-03

[<[e-mail]>]

I forget to add that the security considerations should be updated as follow:

existing text in section 11:

   Diameter does not include features to provide end-to-end
   authentication, integrity protection, or confidentiality.  This opens
   the possibility that agents in the path of a request could modify the
   DRMP AVP to reflect a priority different than that asserted by the
   sender of the request.

new proposed text (adding malicious or compromised)

   Diameter does not include features to provide end-to-end
   authentication, integrity protection, or confidentiality.  This opens
   the possibility that malicious or compromised agents in the path of
   a request could modify the DRMP AVP to reflect a priority different
   than that asserted by the sender of the request.

regards,

Lionel

De : MORAND Lionel IMT/OLN
Envoyé : mercredi 9 mars 2016 17:05
À : 'Janet P Gunn'; Steve Donovan
Cc : [e-mail]; DiME; Stephen Farrell
Objet : RE: [Dime] AD review of draft-ietf-dime-drmp-03

Hi Steve,

It is true that some scenarios will require action of agents on the DRMP AVP.

in that case, I would be more explicit and change a little bit the order as "save the transaction priority" is valid in any case:

è  Note that the title of the bullet 2 should be " Agents handing the request " and not "Agents handling the request"

   2.  Agents handling the request - Agents use the priority information
       when making routing decisions.  This can include determining
       which requests to route first, which requests to throttle and
       where the request is routed.  For instance, requests with higher
       priority might have a lower probability of being throttled.  The
       mechanism for how the agent determines which requests are
       throttled is implementation dependent and is outside the scope of
       this document.  Before forwarding request messages, agents generally do not
       modify the priority information present in the received request
       message nor include the priority information when absent in the received request message.
       However, in some scenarios, agents
       can modify the priority information e.g. edge agents modifying the
       priority  values set by an adjacent operator. There might be other
       scenarios where a Diameter endpoint does not support the DRMP
       mechanism and agents insert the priority information in the request messages for that non
       supporting endpoint. When forwarding the request messages, the agent saves
       the transaction priority in the transaction state, either as
       locally managed state or using the Proxy-Info mechanism defined
       in [RFC6733<https://tools.ietf.org/html/rfc6733>].  This will be used when handling the associated
       answer message for the transaction.


The same kind of change should be done in bullet 5 that is about handling of answers:

   5.  Agent handling the answer - By default, agents handling answer
       messages use the priority information stored with the transaction
       state to determine the priority of relaying the answer message.
       However, priority information included in the answer message,
       when present, is used in place of the stored priority
       information.  The use of priority information implies that
       answers for higher priority transactions are given preferential
       treatment to lower priority transactions. When forwarding the answer messages, agents generally do not
       modify the priority information present in the received answer messages
       nor include the priority information when absent in the received answer messages.
       However, in some scenarios, agents
       can modify the priority information e.g. edge agents modifying the
       priority  values set by an adjacent operator. There might be other
       scenarios where a Diameter endpoint does not support the DRMP
       mechanism and agents insert the priority information for that non
       supporting endpoint.

If it is agreed that agents can modify/include the DRMP AVP, I think that the "SHOULD NOT" is not correct as it is a "MAY", even if not often.
I think the proposed added requirements can be safely removed.

Regards,

Lionel

De : Janet P Gunn [mailto:[e-mail]]
Envoyé : mercredi 9 mars 2016 16:23
À : Steve Donovan
Cc : [e-mail]<mailto:[e-mail]>; DiME; MORAND Lionel IMT/OLN; Stephen Farrell
Objet : Re: [Dime] AD review of draft-ietf-dime-drmp-03

Sounds good to me.

Janet

This electronic message transmission contains information from CSRA that may be attorney-client privileged, proprietary or confidential. The information in this message is intended only for use by the individual(s) to whom it is addressed. If you believe you have received this message in error, please contact me immediately and be aware that any use, disclosure, copying or distribution of the contents of this message is strictly prohibited. NOTE: Regardless of content, this email shall not operate to bind CSRA to any order or other contract unless pursuant to explicit written agreement or government initiative expressly permitting the use of email for such purpose.



From:        Steve Donovan <[e-mail]<mailto:[e-mail]>>
To:        [e-mail]<mailto:[e-mail]>, Stephen Farrell <[e-mail]<mailto:[e-mail]>>, "[e-mail]<mailto:[e-mail]>" <[e-mail]<mailto:[e-mail]>>
Date:        03/09/2016 10:15 AM
Subject:        Re: [Dime] AD review of draft-ietf-dime-drmp-03
Sent by:        "DiME" <[e-mail]<mailto:[e-mail]>>
________________________________



All,

I've commented on Stephen's and Lionel's suggested changes below.

If there is agreement to my proposed changes outlined below then I will submit a new version of the document.

Regards,

Steve

On 3/8/16 9:41 AM, [e-mail]<mailto:[e-mail]> wrote:
i will let Steve react but I can give my feeling :)

The priority is set by the Diameter or Diameter server, not by agent.

It is somehow describe in section 6 Theory of Operation

  2.  Agents handing the request - Agents use the priority information
      when making routing decisions.  This can include determining
      which requests to route first, which requests to throttle and
      where the request is routed.  For instance, requests with higher
      priority might have a lower probability of being throttled.  The
      mechanism for how the agent determines which requests are
      throttled is implementation dependent and is outside the scope of
      this document.  The agent also saves the transaction priority in
      the transaction state, either as locally managed state or using
      the Proxy-Info mechanism defined in [RFC6733].  This will be used
      when handling the associated answer message for the transaction.

Agents are just using this information if present. They are not modify it or include it if absent.
It is said in section 8.  Normative Behavior

     Note: This guidance on the handling of messages without a priority
     does not result in a Diameter agent inserting a DRMP AVP into the
     message.  Rather, it gives guidance on how that specific
     transaction should be treated when its priority is compared with
     other requests.  When a Diameter agent relays the request it will
     not insert a DRMP AVP with a priority value of 10.

It could be possible to clarify it as follow:

in section 6, the end of the point 2 could be enhanced as follow:

  2.  Agents *handling* the request - Agents use the priority information
      when making routing decisions.  This can include determining
      which requests to route first, which requests to throttle and
      where the request is routed.  For instance, requests with higher
      priority might have a lower probability of being throttled.  The
      mechanism for how the agent determines which requests are
      throttled is implementation dependent and is outside the scope of
      this document.  The agent also saves the transaction priority in
      the transaction state, either as locally managed state or using
      the Proxy-Info mechanism defined in [RFC6733].  This will be used
      when handling the associated answer message for the transaction.
      *Agents are not supposed to modify or include priority information in
      in forwarded requests or answers.*
SRD> I propose the following reworded last sentence: "Agents generally do no modify priority
information and agents generally do not add new priority information in forwarded requests or answers."

SRD> There is one scenario where I can see an agent does add add priority information, in a
transition period when not all endpoints support the DRMP mechanism and the agent
is used to insert priority information for the non supporting endpoint.

SRD> I also see one scenario where an agent might modify priority values.  This would
be an edge agent case where the priority values included by another operator's Diameter
network aren't trusted and new values are needed.

SRD> I propose that notes that address these scenarios  be added to the new normative requirements proposed below.


The "not supposed" is used because it is difficult to use normative wording here.

In section 8, a new requirement could be added, right after " Diameter agents MAY use routing priority information..."

  Diameter agents SHOULD NOT modify or include the DRMP AVP when
  relaying request and answer messages.
SRD> I propose the following:
   Diameter agents SHOULD NOT modify priority information when relaying
  request and answer messages.

     There might be scenarios where a Diameter agent does modify
     priority information.  For instance, an edge agent might need to
     modify the priority values set by an adjacent operator.

  Diameter agents SHOULD NOT add priority information when relaying
  request and answer messages.

     There might be scenarios where a Diameter endpoint does not
     support the DRMP mechanism and agents insert priority information
     for that non supporting endpoint.


Just a proposal, waiting for Steve and WG comments.

Regards,

Lionel



-----Message d'origine-----
De : DiME [mailto:[e-mail]] De la part de Stephen Farrell
Envoyé : vendredi 4 mars 2016 18:07
À : [e-mail]<mailto:[e-mail]>
Objet : [Dime] AD review of draft-ietf-dime-drmp-03


Hiya,

I just have one question I'd like to ask the wg about before I start IETF LC.

You don't say if priorities are intended to be modified after they have been
set. In the security considerations you do say that this could be done
maliciously, and you do say that priorities need to be dropped if received
from a source not trusted for that, but you never say if it's considered ok or
not for e.g. an agent to change a priority for some local policy reason. Don't
you need to say that somewhere? (And apologies if you do say it somewhere
and I missed it:-)

There are some nits below, you can handled these before or after IETF LC,
whichever is best.

Cheers,
S.


- Section 5: URL and MME aren't expanded. Since you're just using it as an
example, I'd say expanding this will help any reader who's not a 3gpp
afficionado.
SRD> Change made.


- Section 8, "The priority marking scheme SHOULD NOT require the Diameter
Agents to understand application specific AVPs."
Isn't that a bogus use of 2119 language since we're not expressing
requirements here? s/SHOULD NOT/does not/ would seem better.
SRD> Agreed, change made.


- Section 8, People will ask "why default to 10?" I recall the WG discussed this
but iirc mostly didn't care too much but it might be nice to justify 10 if there's
a way to do it that doesn't amount to "just because" :-)
SRD> I'm open to wording suggestions here but the only real reason is that we needed a default and some thought it might be better to have the default allow for a few more higher-than-default values than lower-than-default values.  I'm not sure saying this adds much value.


- Section 8, The "When setting and using..." paragraphs are quite verbose.
It'd be no harm to make that shorter, e.g. by just saying: "For all integers x,y
in [0,15] treat PRIORITY_<x> as lower priority than PRIOIRTY_<y> when y<x"
You could do something similar in 9.1.
SRD> The existing language was put in when we had 5 priority values.  The above is certainly a more elegant way of specifying it.  Changed to the following:

   When setting and using priorities, for all integers x,y in [0,15]
  treat PRIORITY_<x> as lower priority than PRIOIRTY_<y> when y<x.

     Note: As a result PRIORITY_0 is the highest priority.
SRD> I'm not sure this can be done in section 9.1, as this is listing the enumerated values for the AVP.




I-D nits:

 == Unused Reference: 'RFC5226'
 == Unused Reference: 'RFC4412'
SRD> These references removed.




_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.


_______________________________________________
DiME mailing list
[e-mail]<mailto:[e-mail]>
https://www.ietf.org/mailman/listinfo/dime

_________________________________________________________________________________________________________________________

Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou falsifie. Merci.

This message and its attachments may contain confidential or privileged information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been modified, changed or falsified.
Thank you.