Re: [kitten] Clarification of gss_add_cred() behavior
Nico Williams <nico@cryptonector.com> Fri, 20 March 2015 00:45 UTC
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Date: Thu, 19 Mar 2015 19:45:25 -0500
From: Nico Williams <nico@cryptonector.com>
To: Benjamin Kaduk <kaduk@MIT.EDU>
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Subject: Re: [kitten] Clarification of gss_add_cred() behavior
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On Thu, Mar 19, 2015 at 08:20:18PM -0400, Benjamin Kaduk wrote: > On Thu, 19 Mar 2015, Nico Williams wrote: > > GSS_C_NO_NAME. But then I can never use GSS_Add_cred() to acquire a > > signle-element credential, and I must always use GSS_Acquire_cred() for > > that (which is lame for several reasons). > > Perhaps I'm just being slow today, but could you say more about what these > reasons for lameness are? Sure: - the need to construct an OID set of one OID is lame (this is easy when one has only one or known-fixed-at-compile-time number of OIDs, but it's still lame) - minor_status is not associated with any mechanism per the specs, though one hopes that for the one-OID case minor_status is specific to that one mechanism, but if we're going to be as literal as we can in reading the spec, then this point is correct and GSS_Acquire_cred() is lame - fewer informative outputs (initiator and acceptor lifetime rec) (admittedly this one is not a big deal) The second is the real killer. It's one of the reasons given for the addition of GSS_Add_cred(). And if we interpret the spec as you propose, we can't have this feature. This is one reason to think that the spec is self-inconsistent. Other reasons to think the spec is self-inconsistent: - No information or pseudo-code or code is given showing how to iteratively construct credential handles. It probably wasn't thought through. But if the case of input_cred_handle == GSS_C_NO_CREDENTIAL && desired_name != GSS_C_NO_NAME is interpreted as I propose, then it's trivial to iteratively construct a credential handle. - It makes no sense anyways to ignore a non-default desired_name when the input_cred_handle is GSS_C_NO_CREDENTIAL, not in light of the fact that GSS_C_NO_NAME is how one refers to the default credential in GSS_Acquire_cred() calls. - In some places input_cred_handle is described as optional. Well, but GSS_C_NO_CREDENTIAL -> ignore desired_name means there's no real way to signal "I'm not providing an input cred handle", therefore it's either not optional, or the text I say is wrong is wrong. The RFC text I quoted as broken does not reflect reality for an implementation of the C bindings that I could check. I don't think anyone is proposing to implement the text I quoted. That leaves three choices: - file an erratum - publish an update - do nothing (anyone who runs into this will hopefully find this thread) I will not be submitting an I-D to update the RFCs just for this. If we have no consensus for an erratum, and no one else volunteers for the update, then it's the third choice: do nothing. Nico --
- [kitten] Clarification of gss_add_cred() behavior Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Benjamin Kaduk
- Re: [kitten] Clarification of gss_add_cred() beha… Viktor Dukhovni
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Benjamin Kaduk
- Re: [kitten] Clarification of gss_add_cred() beha… Viktor Dukhovni
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Benjamin Kaduk
- Re: [kitten] Clarification of gss_add_cred() beha… Viktor Dukhovni
- Re: [kitten] Clarification of gss_add_cred() beha… Nico Williams
- Re: [kitten] Clarification of gss_add_cred() beha… Benjamin Kaduk