Horton

Re: SCRAM with channel binding downgrade attack

Bruce Momjian <bruce@momjian.us>

View thread View on postgr.es
From: Bruce Momjian <bruce@momjian.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Robert Haas <robertmhaas@gmail.com>, Magnus Hagander <magnus@hagander.net>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Postgres hackers <pgsql-hackers@postgresql.org>, Stephen Frost <sfrost@snowman.net>
Date: 2018-06-23T03:01:53Z
Lists: pgsql-hackers 
On Sun, Jun 17, 2018 at 10:21:27PM +0900, Michael Paquier wrote:
> On Fri, Jun 15, 2018 at 05:23:27PM -0400, Robert Haas wrote:
> > On Thu, Jun 14, 2018 at 7:43 AM, Magnus Hagander <magnus@hagander.net> wrote:
> >> I still think that the fact that we are still discussing what is basically
> >> the *basic concepts* of how this would be set up after we have released
> >> beta1 is a clear sign that this should not go into 11.
> > 
> > +1.
> 
> Yes, that sounds right.

Uh, as I am understanding it, if we don't allow clients to force channel
binding, then channel binding is useless because it cannot prevent
man-in-the-middle attacks.  I am sure some users will try to use it, and
not understand that it serves no purpose.  If we then allow clients to
force channel binding in PG 12, they will then need to fix their
clients.

I suggest that if we don't allow users to use channel binding
effectively that we should remove all documentation about this feature.

This is different from downgrade attacks like SCRAM to MD5 or MD5 to
'password' because the way the password is transmitted is not integral
to preventing man-in-the-middle attacks.  Channel binding's sole value
is to prevent such attacks, so if it cannot prevent them, it has no use
and will just confuse people until we make it useful in a later release.

-- 
  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.