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Re: SOP wiki was: A Somewhat Critical View of SOP (Same Origin Policy)

From: Henry Story <henry.story@co-operating.systems>
Date: Tue, 29 Sep 2015 13:48:30 +0100
Cc: Dave Longley Longley <dlongley@digitalbazaar.com>, Dave Raggett <dsr@w3.org>, Carvalho Melvin <melvincarvalho@gmail.com>, Martin Paljak <martin.paljak@ria.ee>, "public-web-security@w3.org" <public-web-security@w3.org>, WebAppSec WG <public-webappsec@w3.org>, GALINDO Virginie <Virginie.Galindo@gemalto.com>
Message-Id: <52AFDD72-1DB3-4C55-A08E-1407C67BF45D@co-operating.systems>
To: Jeff Hodges <jeff.hodges@paypal.com>

> On 29 Sep 2015, at 00:23, Hodges, Jeff <jeff.hodges@paypal.com> wrote:
> the claims made in https://www.w3.org/Security/wiki/IG/a_view_on_SOP#FIDO <https://www.w3.org/Security/wiki/IG/a_view_on_SOP#FIDO> are incorrect — perhaps whoever wrote them did not read the spec in question carefully.  here's what I just entered in that wiki section:
> _THE ABOVE CLAIM IS INCORRECT_ "such as other web origins within the same DNS zone of control of the AppID's origin" essentially means that what is colloquially known as "domain lowering" (as in what is colloquially known as the "cookie same origin policy") is used to determine if a given web origin is "within the same DNS zone of control of the AppID's origin". How to determine this is specified in <https://fidoalliance.org/specs/fido-uaf-v1.0-ps-20141208/fido-appid-and-facets-v1.0-ps-20141208.html#determining-if-a-caller-s-facetid-is-authorized-for-an-appid <https://fidoalliance.org/specs/fido-uaf-v1.0-ps-20141208/fido-appid-and-facets-v1.0-ps-20141208.html#determining-if-a-caller-s-facetid-is-authorized-for-an-appid>> Step 14. See also 'HTTP cookie processing algorithm in terms of Same Origin Policy and “effective Top Level Domains (eTLDs)” aka “Public Suffixes”' <http://identitymeme.org/http-cookie-processing-algorithm-etlds/ <http://identitymeme.org/http-cookie-processing-algorithm-etlds/>>. =JeffH 
Thanks Jeff for the input.  

I think this suggests that we need to look more carefully at the definition of SOP.
I should add a section at the top of the wiki on that.

Tony Arcieri has put forward a strict defintion of Same Origin in his mail today [1].
For him two origins are the same if and only if they have the same scheme, domain 
and port. "Anything besides this is not following SOP." he adds. This reasoning 
leads him to the conclusion that cookies are broken. "RFC-6265 is in effect telling 
us that cookies are broken because a long time ago Netscape made some bad decisions."

Tony's definition is what I would call strict Same Origin. [2] In opposition to this you want 
to define a weaker notion of Same Origin, following the Cookie Processing Algorithm
you cite, and for which there are some nice examples in the FIDO Facets document [3].

It is clear that the weaker notion of same origin has a wider identity criterion, that
aims to be more flexible in its notion of origin, in that a number of Origin URIs identify
the same agent. 

But according to Tony Acieri this weaker notion is not a notion of same origin at all.
If so, and if he does not wish to also argue that FIDO is broken, then we need to understand
what enables FIDO to expand from the notion of origin, or put in Alex's language how FIDO
allows trust between origins to work.  There are a number of ways I can think of arguing 
this point.


[1] https://lists.w3.org/Archives/Public/public-web-security/2015Sep/0118.html <https://lists.w3.org/Archives/Public/public-web-security/2015Sep/0118.html>
[2] I made this distinction in the Cookies section, but should move this up to a SOP
   definitions section
   https://www.w3.org/Security/wiki/IG/a_view_on_SOP#Cookies <https://www.w3.org/Security/wiki/IG/a_view_on_SOP#Cookies>
[3] https://fidoalliance.org/wp-content/uploads/html/fido-appid-and-facets-v1.0-ps-20141208.html#appid-example-1 <https://fidoalliance.org/wp-content/uploads/html/fido-appid-and-facets-v1.0-ps-20141208.html#appid-example-1>
  Mind you I don't quite understand why 

can have 


as an equivalent weak Same Origin, but 


cannot have 


as an equivalent same origin. ( The result makes sense, but the rules are not easy to follow )

> On 9/28/15, 12:47 PM, "GALINDO Virginie" <Virginie.Galindo@gemalto.com <mailto:Virginie.Galindo@gemalto.com>> wrote:
> Henry, 
> I believe that the wiki page should start by  writing use cases, and not re-explaning SOP cons and your technical vision. If you want to trigger collaborative thinking, thanks for exposing: 
> - Use case,
> - What feature in your use cases can't be achieved with today's technical rules.
> And then we will be able to have technical discussions about potentiel solutions.
> Regards 
> Virginie
> ---- Henry Story a écrit ----
> > On 25 Sep 2015, at 15:38, GALINDO Virginie <Virginie.GALINDO@gemalto.com <mailto:Virginie.GALINDO@gemalto.com>> wrote:
> > 
> > Thanks for completing your use case on the wiki dedicated to that topic, guys !
> > https://www.w3.org/Security/wiki/IG/a_view_on_SOP <https://www.w3.org/Security/wiki/IG/a_view_on_SOP>
> > 
> > Regards,
> > Virginie
> Thanks Virginie for the great idea of putting up this wiki. Mailing list
> discussions are very educational if one follows them with great care, but
> it is very difficult for people who jump in from the outside in mid conversation
> or who are following from the sidelines to understand what if anything has 
> been gained by the discussion.
> I have brought together a lot of what I have learnt about SOP with many
> references to IETF and W3C specs, pointers to new evolutions in the webapp(sec)
> groups, and discussion with community members on the wiki
>   https://www.w3.org/Security/wiki/IG/a_view_on_SOP <https://www.w3.org/Security/wiki/IG/a_view_on_SOP>
> This weekend I re-arranged the wiki into three pieces
> 1. Conceptual map : just to give an idea how work from privacy, identity,
> security, logic, and other areas bear on the issue. There are still pieces
> to be filled out here.
> 2. Exceptions to SOP:
>   the more I look around the more I have found well documented and justified
> exceptions to narrow understandings of SOP. This should give us some good raw
> material for a later exploration of a theory of SOP.
> 3. Implications for Future standards.
>   A third section on who SOP is bringing up issues for future requirements such as 
> WebPayments.
> 4. Theory of SOP
>   Here I think we'll be able to bring together an extended theory of SOP
> that makes sense of the exceptions, whilst showing how these tie into other elements of the conceptual spaces. My feeling is that a bit of work  in some very initial modal logic of belief contexts would help give a secure logical foundation. 
> I think this is taking shape. Of course there will be errors, improvements. It is not
> complete, so feedback is welcome.
> Henry
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Received on Tuesday, 29 September 2015 12:49:10 UTC

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