Re: Possibility to disable `ALTER SYSTEM`

On Tue, Mar 19, 2024 at 2:28 PM Magnus Hagander <magnus(at)hagander(dot)net> wrote:

> On Tue, Mar 19, 2024 at 3:52 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >
> > Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> > > Perhaps we could make that even better with a GUC though. I propose a
> > > GUC called 'configuration_managed_externally = true / false". If you
> set
> > > it to true, we prevent ALTER SYSTEM and make the error message more
> > > definitive:
> >
> > > postgres=# ALTER SYSTEM SET wal_level TO minimal;
> > > ERROR: configuration is managed externally
> >
> > > As a bonus, if that GUC is set, we could even check at server startup
> > > that all the configuration files are not writable by the postgres user,
> > > and print a warning or refuse to start up if they are.
> >
> > I like this idea. The "bonus" is not optional though, because
> > setting the files' ownership/permissions is the only way to be
> > sure that the prohibition is even a little bit bulletproof.
> >
> > One small issue: how do we make that work on Windows? Have recent
> > versions grown anything that looks like real file permissions?
>
> Windows has had full ACL support since 1993. The easiest way to do
> what you're doing here is to just set a DENY permission on the
> postgres operating system user.
>
>
>
>

Yeah. See <
https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/icacls>
for example.

cheers

andrew