So it turns out that it was indeed a problem with my configuration rather than postgresql -- my bad.
It looks like Ubuntu 21.04 adds the following to the configs:
ssl_cert_file = '/etc/ssl/certs/ssl-cert-snakeoil.pem'
ssl_key_file = '/etc/ssl/private/ssl-cert-snakeoil.key'
I was able to find this through the reset_val column in pg_settings. Thanks for the help everyone!
Yongqian Li <yongqli@kerrmetric.com> writes:
> I encountered this problem while I was trying to enable SSL on my
> postgresql server. Since I was satisfied with the default values for the
> "ssl_key_file" and "ssl_cert_file" settings I chose to not configure them
> -- I simply turned on "ssl" and copied over the files to the default
> locations. However, I kept getting certificate errors on the client.
> Examining the certificate sent by the server using `openssl s_client
> -starttls postgres -connect "$HOSTNAME:5432"` revealed that the server was
> sending some auto-generated cert instead of the one in "server.crt".
> Setting the "ssl_key_file" and "ssl_cert_file" settings explicitly to their
> default value fixed the problem.
This is pretty hard to believe, and I couldn't duplicate it in a simple
test:
1. Make a server certificate as per the recipe at
https://www.postgresql.org/docs/current/ssl-tcp.html#SSL-CERTIFICATE-CREATION
(I followed the variant with a private certificate authority.)
2. Copy certificate and key into $PGDATA/server.crt & server.key,
setting appropriate file permissions.
3. Edit postgresql.conf to set "ssl = on", touching nothing else.
4. "pg_ctl reload", check server log to verify that it turned SSL
on. (On older PG versions you might need "pg_ctl restart".)
5. Probe with "openssl s_client".
The certificate returned to s_client is visibly the same one
I put into server.crt. openssl fails to verify it, but that's
no surprise since I didn't tell openssl to trust the private
certificate authority.
I speculate that you forgot to do "pg_ctl reload" after modifying
the server.crt file, or some similar error. If you can really
reproduce this problem, please present an exact reproduction
recipe, and tell us the PG version too.
regards, tom lane