Horton

Re: Postgres 11 release notes

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Magnus Hagander <magnus@hagander.net>, Stephen Frost <sfrost@snowman.net>
Date: 2018-05-17T01:09:22Z
Lists: pgsql-hackers 
On Thu, May 17, 2018 at 09:56:49AM +0900, Michael Paquier 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.

Uh, a man-in-the-middle could prevent SSL or ask for a different
password authentication method and then channel binding would not be
used.  I think when you say you want channel binding, you have to fail
if you don't get it.

> > 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, I don't see a way around it.  Once you accept that someone in the
middle can change what you request undetected, then you can't do 
fallback.  Imagine a man-in-the-middle with TLS where the
man-in-the-middle allows the two end-points to negotiate the shared
secret, but the man-in-the-middle forces a weak cipher.  This is what is
happening with Postgres when the man-in-the-middle forces a weaker
authentication method.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

Commits

  1. doc: update PG 11 release notes

  2. Fix misspelled pg_trgm contrib name in PostgreSQL 11 release notes

  3. Doc: clarify release note text about v11's new window function features.

  4. Improve wording of release notes item

  5. Fix typos in release notes

  6. Doc: preliminary list of PG11 major features.

  7. Make numeric power() handle NaNs according to the modern POSIX spec.

  8. Various improvements of skipping index scan during vacuum technics

  9. Revert back-branch changes in power()'s behavior for NaN inputs.

  10. Avoid wrong results for power() with NaN input on more platforms.

  11. Avoid wrong results for power() with NaN input on some platforms.

  12. Skip full index scan during cleanup of B-tree indexes when possible

  13. Rewrite the code that applies scan/join targets to paths.

  14. Postpone generate_gather_paths for topmost scan/join rel.

  15. Add casts from jsonb

  16. Make plpgsql use its DTYPE_REC code paths for composite-type variables.

  17. Don't allow VACUUM VERBOSE ANALYZE VERBOSE.

  18. Pass InitPlan values to workers via Gather (Merge).

  19. Account for the effect of lossy pages when costing bitmap scans.

  20. Allow no-op GiST support functions to be omitted.

  21. Rearm statement_timeout after each executed query.

  22. Push limit through subqueries to underlying sort, where possible.