Horton

Re: Direct SSL connection with ALPN and HBA rules

Heikki Linnakangas <hlinnaka@iki.fi>

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From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Jacob Champion <jacob.champion@enterprisedb.com>
Cc: Daniel Gustafsson <daniel@yesql.se>, Robert Haas <robertmhaas@gmail.com>, Michael Paquier <michael@paquier.xyz>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-05-13T13:37:50Z
Lists: pgsql-hackers

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On 10/05/2024 16:50, Heikki Linnakangas wrote:
> New proposal:
> 
> - Remove the "try both" mode completely, and rename "requiredirect" to
> just "direct". So there would be just two modes: "postgres" and
> "direct". On reflection, the automatic fallback mode doesn't seem very
> useful. It would make sense as the default, because then you would get
> the benefits automatically in most cases but still be compatible with
> old servers. But if it's not the default, you have to fiddle with libpq
> settings anyway to enable it, and then you might as well use the
> "requiredirect" mode when you know the server supports it. There isn't
> anything wrong with it as such, but given how much confusion there's
> been on how this all works, I'd prefer to cut this back to the bare
> minimum now. We can add it back in the future, and perhaps make it the
> default at the same time. This addresses points 2. and 3. above.
> 
> and:
> 
> - Only allow sslnegotiation=direct with sslmode=require or higher. This
> is what you, Jacob, wanted to do all along, and addresses point 1.

Here's a patch to implement that.

-- 
Heikki Linnakangas
Neon (https://neon.tech)

Commits

  1. Remove option to fall back from direct to postgres SSL negotiation

  2. Reject SSL connection if ALPN is used but there's no common protocol

  3. libpq: Enforce ALPN in direct SSL connections

  4. libpq: If ALPN is not used, make PQsslAttribute(conn, "alpn") == ""

  5. Fix documentation and comments on what happens after GSS rejection

  6. doc: Add note to prevent server spoofing with SCRAM