Re: Delegating superuser tasks to new security roles (Was: Granting control of SUSET gucs to non-superusers) - Mailing list pgsql-hackers

> On Aug 23, 2021, at 11:13 AM, Stephen Frost <sfrost@snowman.net> wrote:
>
> This I have to object to pretty strongly- we have got to get away from
> the idea that just because X isn't a superuser or isn't owned by a
> superuser that it's fine to allow some non-superuser to mess with it.

I thought we were trying to create a set of roles which could cumulatively do everything *inside the sandbox* that
superusercan do, but which cannot escape the sandbox.  I would think this pg_manage_database_objects role would be
reasonablein the context of that effort. 

> In particlar, just because a role isn't explicitly marked as a superuser
> doesn't mean that the role can't *become* a superuser, or that it hasn't
> got privileged access to the system in other ways, such as by being a
> member of other predefined roles that perhaps the role who is a member
> of pg_manage_database_objects doesn't have.

The implementation does not allow pg_manage_database_objects to mess with objects that are owned by a role which
satisfiessuperuser_arg().  If you are renting out a database to a tenant and change the ownership of stuff to a
non-superuser,then you get what you get.  But why would you do that? 

> Such a check against
> modifying of "superuser owned" objects implies that it's providing some
> kind of protection against the role being able to become a superuser
> when it doesn't actually provide that protection in any kind of reliable
> fashion and instead ends up fooling the user.

Please provide steps to reproduce this issue.  Assume that a database is initialized and that everything is owned by
thesystem.  A "tenant" role is created and granted pg_manage_database_objects, and other non-superuser roles are
created. Now, what exactly can "tenant" do that you find objectionable? 

> This is the issue with CREATEROLE and we definitely shouldn't be
> doubling-down on that mistake, and also brings up the point that I, at
> least, had certainly hoped that part of this effort would include a way
> for roles to be created by a user with an appropriate predefined role,
> and w/o CREATEROLE (which would then be deprecated or, ideally, just
> outright removed).

Well, pg_manage_database_objects has no special ability to create or drop roles.  I thought separating those powers
mademore sense than grouping them together.  We can have a new role for doing what you say, but that seems redundant
withCREATEROLE.  I didn't want this patch set to be bogged down waiting for a consensus on how to change the CREATEROLE
privilege.

>  I get that this doesn't have to be in the first
> patch or even patch set going down this road but the lack of discussion
> or of any coordination between this effort and the other one that is
> trying to address the CREATEROLE issue seems likely to land us in a bad
> place with two distinct approaches being used.

I'm confused.  This patch set doesn't come within a country mile of CREATEROLE.  Why should this patch set have to
coordinatewith that one?  I'm not arguing with you -- merely asking what I'm misunderstanding? 

—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company