Horton

Re: Password identifiers, protocol aging and SCRAM protocol

Michael Paquier <michael.paquier@gmail.com>

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From: Michael Paquier <michael.paquier@gmail.com>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: David Steele <david@pgmasters.net>, Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, David Fetter <david@fetter.org>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Julian Markwort <julian.markwort@uni-muenster.de>, Stephen Frost <sfrost@snowman.net>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, Valery Popov <v.popov@postgrespro.ru>
Date: 2016-09-29T03:48:07Z
Lists: pgsql-hackers 
On Wed, Sep 28, 2016 at 8:55 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
>> Our b64_encode routine does use whitespace, so we can't use it as is for
>> SCRAM. As the patch stands, we might never output anything long enough to
>> create linefeeds, but let's be tidy. The base64 implementation is about 100
>> lines of code, so perhaps we should just leave src/backend/utils/encode.c
>> alone, and make a new copy of the base64 routines in src/common.
>
> OK, I'll refresh that tomorrow with the rest. Thanks for the commit to
> extend password_encryption.

OK, so after more chatting with Heikki, here is a list of TODO items
and a summary of the state of things:
- base64 encoding routines should drop whitespace (' ', \r, \t), and
it would be better to just copy those from the backend's encode.c to
src/common/. No need to move escape and binary things, nor touch
backend's base64 routines.
- No need to move sha1.c to src/common/. Better to just get sha2.c
into src/common/ as we aim at SCRAM-SHA-256.
- random() called in the client is no good. We need something better here.
- The error handling needs to be reworked and should follow the
protocol presented by RFC5802, by sending back e= messages. This needs
a bit of work, not much I think though as the infra is in place in the
core patch.
- Let's discard the md5-or-scram optional thing in pg_hba.conf. This
complicates the error handling protocol.

I am marking this patch as returned with feedback for current CF and
will post a new set soon, moving it to the next CF once I have the new
set of patches ready for posting.
-- 
Michael

Commits

  1. Support SCRAM-SHA-256 authentication (RFC 5802 and 7677).

  2. Refactor SHA2 functions and move them to src/common/.

  3. Replace isMD5() with a more future-proof way to check if pw is encrypted.

  4. Remove bogus notice that older clients might not work with MD5 passwords.

  5. Refactor the code for verifying user's password.

  6. Replace PostmasterRandom() with a stronger source, second attempt.

  7. Remove support for (insecure) crypt authentication.