Re: [PATCH v18] GSSAPI encryption support

On Tue, Jun 12, 2018 at 12:36:01PM -0400, Robbie Harwood wrote:
> Nico Williams <nico(at)cryptonector(dot)com> writes:
> > On Mon, Jun 11, 2018 at 04:11:10PM -0400, Robbie Harwood wrote:
> >> Nico was kind enough to provide me with some code review. This should
> >> those concerns (clarify short-read behavior and fixing error checking on
> >> GSS functions).
> >
> > Besides the bug you fixed and which I told you about off-list (on IRC,
> > specifically), I only have some commentary that does not need any
> > action:
> >
> > - support for non-Kerberos/default GSS mechanisms
> >
> > This might require new values for gssmode: prefer-<mechanism-name>
> > and require-<mechanism-name>. One could always use SPNEGO if there
> > are multiple mechanisms to choose from. And indeed, you could just
> > use SPNEGO if the user has credentials for multiple mechanism.
> >
> > (Because GSS has no standard mechanism _names_, this means making
> > some up. This is one obnoxious shortcoming of the GSS-API...)
>
> As long as it's better than passing raw OIDs on the CLI...

Rite?

I think this can be a follow-on patch, though trying SPNEGO if the user
has credentials for multiple mechanisms (and SPNEGO is indicated) seems
simple enough to do now (no interface changes).

> > - when the SCRAM channel binding work is done, it might be good to add
> > an option for TLS + GSS w/ channel binding to TLS and no gss wrap
> > tokens
>
> I think both of these are neat ideas if they'll be used. Getting GSSAPI
> encryption in shouldn't preclude either in its present form (should make
> it easier, I hope), but I'm glad to hear of possible future work as
> well!

This one can (must) wait. It has some security benefits. You get to
use GSS/Kerberos for authentication, but you get an forward security
you'd get from TLS (if the GSS mechanism doesn't provide it, which
Kerberos today does not).

Nico
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