Re: Experiments with Postgres and SSL

On Thu, 19 Jan 2023 at 15:49, Vladimir Sitnikov
<sitnikov.vladimir@gmail.com> wrote:
>
> What if the server that supports 'fast TLS' added an extra notification in case client connects with a classic TLS?
> Then a capable client could remember host:port and try with newer TLS appoach the next time it connects.
>
> It would be transparent to the clients, and the users won't need to configure 'prefer classic or fast TLS'
> The old clients could discard the notification.

Hm. I hadn't really thought about the case of a new client connecting
to an old server. I don't think it's worth implementing a code path in
the server like this as it would then become cruft that would be hard
to ever get rid of.

I think you can do the same thing, more or less, in the client. Like
if the driver tries to connect via SSL and gets an error it remembers
that host/port and connects using negotiation in the future.

In practice though, by the time drivers support this it'll probably be
far enough in the future that they can just enable it and you can
disable it if you're connecting to an old server. The main benefit for
the near term is going to be clients that are specifically designed to
take advantage of it because it's necessary to enable the environment
they need -- like monitoring tools and proxies.

I've attached the POC. It's not near committable, mainly because of
the lack of any proper interface to the added fields in Port. I
actually had a whole API but ripped it out while debugging because it
wasn't working out.

But here's an example of psql connecting to the same server via
negotiated SSL or through stunnel where stunnel establishes the SSL
connection and psql is just doing plain text:

stark@hatter:~/src/postgresql$ ~/pgsql-sslhacked/bin/psql
'postgresql://localhost:9432/postgres'
psql (16devel)
SSL connection (protocol: TLSv1.3, cipher: TLS_AES_256_GCM_SHA384,
compression: off)
Type "help" for help.

postgres=# select * from pg_stat_ssl;
  pid  | ssl | version |         cipher         | bits | client_dn |
client_serial | issuer_dn
-------+-----+---------+------------------------+------+-----------+---------------+-----------
 48771 | t   | TLSv1.3 | TLS_AES_256_GCM_SHA384 |  256 |           |
            |
(1 row)

postgres=# \q
stark@hatter:~/src/postgresql$ ~/pgsql-sslhacked/bin/psql
'postgresql://localhost:8999/postgres'
psql (16devel)
Type "help" for help.

postgres=# select * from pg_stat_ssl;
  pid  | ssl | version |         cipher         | bits | client_dn |
client_serial | issuer_dn
-------+-----+---------+------------------------+------+-----------+---------------+-----------
 48797 | t   | TLSv1.3 | TLS_AES_256_GCM_SHA384 |  256 |           |
            |
(1 row)


-- 
greg