Re: Removing pg_pltemplate and creating "trustable" extensions

Stephen Frost <[email protected]> Mon, 13 Jan 2020 13:40:19 -0500
Newsgroups	gmane.comp.db.postgresql.devel.general
Message-ID	<[email protected]>
Greetings,

* Tom Lane ([email protected]) wrote:
> Stephen Frost <[email protected]> writes:
> > To be clear, I was advocating for a NEW DB-level privilege ('INSTALL' or
> > 'CREATE EXTENSION' if we could make that work), so that we have it be
> > distinct from CREATE (which, today, really means 'CREATE SCHEMA').
> 
> I still say this is wrong, or at least pointless, because it'd be a
> right that any DB owner could grant to himself.

Yes, of course it is, that the DB owner would have this privilege was
something you agreed to in the prior email- I'd rather not just have a
"if (DBOwner())" check, I'd rather use our actual privilege system and
have this be a right that the DB owner has but can then GRANT out to
others if they wish to.

I'm certainly not suggesting that such a privilege wouldn't be
controlled by the DB owner.  Forcing it to only be allowed for the DB
owner and not be something that the DB owner can GRANT out isn't much
better than "if (superuser())"-style checks.

> If we're to have any
> meaningful access control on extension installation, the privilege
> would have to be attached to some other object ... and there's no clear
> candidate for what.

Extensions are installed at the DB level, not at any other level, and
therefore that's the appropriate place to attach them, which is exactly
what I'm suggesting we do here.

> As someone noted awhile back, if we could somehow
> attach ACLs to potentially-installable extensions, that might be an
> interesting avenue to pursue.  That's well beyond what I'm willing
> to pursue for v13, though.

Sure, having some catalog of installable extensions where someone (in my
thinking, the DB owner) could GRANT out access to install certain
extensions to others might be interesting, but it's not what I'm
suggesting here.

> In the meantime, though, this idea as stated doesn't do anything except
> let a DB owner grant install privileges to someone else.  I'm not even
> convinced that we want that, or that anyone needs it (I can recall zero
> such requests related to PLs in the past).  And for sure it does not
> belong in a minimal implementation of this feature.

Yes, that's what this approach would do.  I suppose an alternative would
be to lump it in with "CREATE" rights on the DB, but I've advocated and
will continue to advocate for splitting up of such broad rights.
DB-level CREATE rights currently cover both schemas and publications,
for example, even though the two have rather little to do with each
other.

If the only agreeable option is a if (DBOwner())-type check, or lumping
the privilege to CREATE (trusted) EXTENSION in with other DB-level
CREATE rights, then I'll go along with one of those.  I'll be happy
enough with that, since it avoids having an additional default role that
has to be GRANT'd by a superuser.  Ideally, down the road, we'll split
out the CREATE privilege (both at DB and at schema level) to be more
fine grained, but that can certainly be done later.

Thanks,

Stephen
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