Re: Preventing non-superusers from altering session authorization

Joseph Koshakow <koshy44@gmail.com>

From: Joseph Koshakow <koshy44@gmail.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-07-01T15:33:51Z
Lists: pgsql-hackers
>> That might be a good change? If the original authenticated role ID no
>> longer exists then we may want to return an error when trying to set
>> your session authorization to that role.
>
> I was curious why we don't block DROP ROLE if there are active sessions
for
> the role or terminate any such sessions as part of the command, and I
found
> this discussion from 2016:
>
>        https://postgr.es/m/flat/56E87CD8.60007%40ohmu.fi

Ah, that makes sense that we don't prevent DROP ROLE on active roles.
Though, we do error when you try and set your role or session
authorization to a dropped role. So erroring on RESET SESSION
AUTHORIZATION when the original role is dropped makes it consistent
with SET SESSION AUTHORIZATION TO <dropped-original-role>. On the other
hand it makes it inconsistent with RESET ROLE, which does not error on
a dropped role.

- Joe Koshakow

On Fri, Jun 23, 2023 at 1:54 PM Nathan Bossart <nathandbossart@gmail.com>
wrote:

> On Thu, Jun 22, 2023 at 06:39:45PM -0400, Joseph Koshakow wrote:
> > On Wed, Jun 21, 2023 at 11:48 PM Nathan Bossart <
> nathandbossart@gmail.com>
> > wrote:
> >> I see that RESET SESSION AUTHORIZATION
> >> with a concurrently dropped role will FATAL with your patch but succeed
> >> without it, which could be part of the reason.
> >
> > That might be a good change? If the original authenticated role ID no
> > longer exists then we may want to return an error when trying to set
> > your session authorization to that role.
>
> I was curious why we don't block DROP ROLE if there are active sessions for
> the role or terminate any such sessions as part of the command, and I found
> this discussion from 2016:
>
>         https://postgr.es/m/flat/56E87CD8.60007%40ohmu.fi
>
> --
> Nathan Bossart
> Amazon Web Services: https://aws.amazon.com
>

Commits

  1. Fix privilege check for SET SESSION AUTHORIZATION.

  2. Move privilege check for SET SESSION AUTHORIZATION.

  3. Rename session_auth_is_superuser to current_role_is_superuser.