Horton

Re: SCRAM with channel binding downgrade attack

Magnus Hagander <magnus@hagander.net>

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From: Magnus Hagander <magnus@hagander.net>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Bruce Momjian <bruce@momjian.us>, Michael Paquier <michael@paquier.xyz>, Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Postgres hackers <pgsql-hackers@postgresql.org>, Stephen Frost <sfrost@snowman.net>
Date: 2018-06-28T07:35:57Z
Lists: pgsql-hackers 
On Wed, Jun 27, 2018 at 7:24 PM, Alvaro Herrera <alvherre@2ndquadrant.com>
wrote:

> Going over this thread a little bit I'm confused about what is being
> proposed.  I think I understand that we no longer think we have have
> SCRAM channel binding.  I hope that doesn't mean we don't have SCRAM
> itself.  However, in terms of the Postgres release proper, what do we
> need to do?  There is still an open item about this, and I had the
> impression that if we simply demoted channel binding from a pg11 major
> feature to barely a footnote that somebody can implement it with some
> hypothetical future JDBC driver that supports the option, then we're
> done.
>
> Am I mistaken?
>

No, we absolutely still have SCRAM channel binding.

*libpq* has no way to *enforce* it, meaning it always acts like our default
SSL config which is "use it if available but if it's not then silently
accept the downgrade". From a security perspective, it's just as bad as our
default ssl config, but unlike ssl you can't configure a requirement in 11.

There is nothing preventing a third party driver like jdbc or npgsql to
implement a way to enforce it. I would generally recommend they wait for
the outcome of the discussion about parameters and names in order to
implement the same semantics, but they don't have to wait for the next
postgres release.

It doesn't affect the having of SCRAM at all. That one is still there, and
has been since 10.

-- 
 Magnus Hagander
 Me: https://www.hagander.net/ <http://www.hagander.net/>
 Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>

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.