Re: apt.postgresql.org repo via https will fail will some users starting 2021-10-01

On Thu, Sep 09, 2021 at 05:33:51PM +0200, Christoph Berg wrote:
> Re: Stefan Huehner
> > > > - Some on the website
> > > > - Think on reconfiguring certbot/Let's Encrypt on the server to switch to the alternative chain (avoiding this bug but breaking compatibility with old Android
> > >
> > > That's probably rather the ca-certificates package?
> >
> > Not in this case, i know a bit confusing.
> > That upstream article has more details:
> > https://community.letsencrypt.org/t/openssl-client-compatibility-changes-for-let-s-encrypt-certificates/143816
> > Part: How to support older OpenSSL versions
> >
> > In (not so) short: ca-certificates is fine to have trust anchor for Lets Encrypt.
> > However not everybody directly trust Let's Encrypt (missing entry in their equivalent of ca-certificates (i.e. old Android).
> >
> > To keep those other clients supported they employed a bit of a trick which has an 'expired root certificates' in the chain from your server-cert to their root. At the same time there is 2nd valid path. But old version of software (openssl,gnutls) just stop + fail on seeing 'expired'.
> >
> > Best they could do if offer server owner (certbot parameter when requesting ssl certificate to select):
>
> Ah, I thought you meant the end-users servers running PostgreSQL when
> you said "server".
Sorry for the confusion.

But now thinking they could be affected (but special cases only)
- There may be a case for running PostgreSQL instances
- As this affects any 'client' using above older libraries
- libpq linked with old ssl, connecting via SSL to remote pg having Let's Encrypt and client validating certificate (verify-ca,verify-full)
- or outgoing connections using fdw

Note:
This is just me trying to construct a flow which might fail.
Again kind of 'info for supporting users' as bug is libssl we link against only.
Maybe also interesting to spread to the yum-side of things (Devrim?) to check thei rpm using packaging/distros.
But also not sure if that is common enough even to make a big topic out of...

>
> For changing the webservers, we'd need to get pginfra on board, Cc'ed
> now.

For the sysadmins:
- 'changing' would avoid the bug described here + not for debian
https://lists.debian.org/debian-lts/2021/09/msg00008.html
for people running old distros (no fix, or not updated, ...)
- But it will break using the webserver with other clients (i.e. older android)
- Need to pick the 'smaller problem' based on the concrete site and its users/clients
- This is generic Let's Encrypt topic (not just apt.postgresql.org host)
- Above letsencrypt link has bigger explanation + all the background

Stefan