We have a customer using a patch to harden their PostgreSQL installation
(see attached) they would like to contribute. This patch adds the ability
to disable "trust" and "ident" authentication at compile time via configure
options, thus making it impossible to use these authentication methods for
sloppy configuration purposes. This is critical to their software
deployment, as stated in their use case description:
<snip>
PostgreSQL is deployed as part of a larger technical solution (e.g. a
Telecommunication system) and a field engineer has to install/upgrade this
solution. The engineer is a specialist in the Telco domain and has only
little knowledge of databases and especially PostgreSQL setup.
We now want to provide these kinds of users with pre-hardened packages that
make it very hard to accidentally expose their database. For this purpose
the patch allows to optionally disable the "trust" and "ident"
authentication methods. Especially the "trust" mechanism is very critical
as it might actually provide useful functionality for our user. Think of an
engineer who has to do a night shift upgrade with a customer breathing down
his neck to get the system back online. Circumventing all these
authentication configuration issues by just enabling "trust" is very easy
and looks well supported and documented. (the documentation states the
dangers but there are no *big red flags* or something). After finishing the
upgrade the engineer forgets to restore the secure configuration, and a
malicious attacker later uses this access method to gain access to the
database.
</snip>
Currently the patch adds new configure options --without-trust-auth and
--without-ident-auth and makes "peer" authentication default when these
options are set. My testing shows that regression tests (which are normally
using trust) are still working. This works as far as it goes to Linux and
friends, Windows currently is not adressed yet. Maybe its worth to consider
making "sspi" the default on this platform instead.
There was a discussion some time ago ([1]), but i think the reasoning
behind this patch is a little bit different than discussed there.
[1]
<http://www.postgresql.org/message-id/CAN2Y=uMt7CPkxZhAUfw7SzecKdWCWsUuLmh4XPhUxKqBtdUoyA@mail.gmail.com>
--
Thanks
Bernd