Horton

Re: SCRAM with channel binding downgrade attack

Heikki Linnakangas <hlinnaka@iki.fi>

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From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Magnus Hagander <magnus@hagander.net>
Cc: Michael Paquier <michael@paquier.xyz>, Bruce Momjian <bruce@momjian.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Stephen Frost <sfrost@snowman.net>
Date: 2018-05-23T09:08:35Z
Lists: pgsql-hackers 
On 23/05/18 09:59, Magnus Hagander wrote:
>> With that, a connection would be allowed, if either the server's SSL
>> certificate is verified as with "sslmode=verify-full", *or* SCRAM
>> authentication with channel binding was used. Or perhaps cram it into
>> sslmode, "sslmode=verify-full-or-scram-channel-binding", just with a
>> nicer name. (We can do that after v11 though, I think.)
> 
> sslmode=verify-full is very different from SCRAM with channel binding,
> isn't it? As in, SCRAM with channel binding at no point proves which server
> you're talking to -- only that you are talking to the SSL endpoint? It
> could be a rogue SSL endpoint unless you do certificate validation.

SCRAM, even without channel binding, does prove that you're talking to 
the correct server. Or to be precise, it proves to the client, that the 
server also knows the password, so assuming that you're using strong 
passwords and not sharing them across servers, you know that you're 
talking to the correct server.

Channel binding adds the guarantee that the SSL endpoint belongs to the 
same server you're authenticating with, i.e. there is no man in the middle.

- Heikki

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.