On Thu, May 17, 2018 at 2:56 AM, Michael Paquier <mich...@paquier.xyz> wrote:
> On Wed, May 16, 2018 at 08:20:49PM -0400, Bruce Momjian wrote: > > SCRAM-with-binding is the first password method that attempts to avoid > > man-in-the-middle attacks, and therefore is much less likely to be able > > to trust what the endpoints supports. I think it is really the > > channel_binding_mode that we want to control at the client. The lesser > > modes are much more reasonable to use an automatic best-supported > > negotiation, which is what we do now. > > Noted. Which means that the parameter is ignored when using a non-SSL > connection, as well as when the server tries to enforce the use of > anything else than SCRAM. > (apologies if this was covered earlier, as I'm entering late into the discussion) "ignored" in combination with a security parameter is generally a very very red flag. If the client requests channel binding and ends up using a non encrypted connection, surely the correct thing to do is fail the connection, rather than downgrade the authentication? We should really make sure we don't re-implement something as silly as our current "sslmode=prefer", because it makes no sense. From the client side perspective, there really only needs to be two choices -- "enforce channel binding at level <x>" or "meh, I don't care". In the "meh, I don't care" mode, go with whatever the server picks (through enforcement in pg_hba.conf for example). > FYI, I think the server could also require channel binding for SCRAM. We > > already have scram-sha-256 in pg_hba.conf, and I think > > scram-sha-256-plus would be reasonable. > > Noted as well. There is of course the question of v10 libpq versions > which don't support channel binding, but if an admin is willing to set > up scram-sha-256-plus in pg_hba.conf then he can request his users to > update his drivers/libs as well. > Yes. And they *should* fail if they don't upgrade. That's what requirement means... :) What's the take of others? Magnus, Stephen or Heikki perhaps (you've > been the most involved with SCRAM early talks)? > Saw it by luck. It would probably be better if it wasn't hidden deep in a thread about release notes. -- Magnus Hagander Me: https://www.hagander.net/ <http://www.hagander.net/> Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>
