Horton

Re: pg_authid.rolpassword format (was Re: Password identifiers, protocol aging and SCRAM protocol)

Stephen Frost <sfrost@snowman.net>

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From: Stephen Frost <sfrost@snowman.net>
To: David Fetter <david@fetter.org>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Michael Paquier <michael.paquier@gmail.com>, Andres Freund <andres@anarazel.de>, David Steele <david@pgmasters.net>, Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>, Magnus Hagander <magnus@hagander.net>, Julian Markwort <julian.markwort@uni-muenster.de>, PostgreSQL mailing lists <pgsql-hackers@postgresql.org>, Valery Popov <v.popov@postgrespro.ru>
Date: 2016-12-21T00:54:52Z
Lists: pgsql-hackers 
David,

* David Fetter (david@fetter.org) wrote:
> On Tue, Dec 20, 2016 at 06:14:40PM -0500, Stephen Frost wrote:
> > * David Fetter (david@fetter.org) wrote:
> > > On Tue, Dec 20, 2016 at 08:34:19AM -0500, Stephen Frost wrote:
> > > > * Heikki Linnakangas (hlinnaka@iki.fi) wrote:
> > > > > Even if you have a separate "verifier type" column, it's not fully
> > > > > normalized, because there's still a dependency between the
> > > > > verifier and verifier type columns. You will always need to look
> > > > > at the verifier type to make sense of the verifier itself.
> > > > 
> > > > That's true- but you don't need to look at the verifier, or even
> > > > have *access* to the verifier, to look at the verifier type.
> > > 
> > > Would a view that shows only what's to the left of the first semicolon
> > > suit this purpose?
> > 
> > Obviously a (security barrier...) view or a (security definer) function
> > could be used, but I don't believe either is actually a good idea.
> 
> Would you be so kind as to help me understand what's wrong with that idea?

For starters, it doubles-down on the assumption that we'll always be
happy with that particular separator and implies to anyone watching that
they'll be able to trust it.  Further, it's additional complication
which, at least to my eyes, is entirely in the wrong direction.

We could push everything in pg_authid into a single colon-separated text
field and call it simpler because we don't have to deal with those silly
column things, and we'd have something a lot closer to a unix passwd
file too!, but it wouldn't make it a terribly smart thing to do.  We
aren't a bunch of individual C programs having to parse out things out
of flat text files, after all.

Thanks!

Stephen

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.