On Thu, 2025-08-21 at 17:36 +0200, Karsten Hilbert wrote:
> PG 17 documentation says that using "WITH ADMIN" allows the
> role being added to another group role to grant/revoke
> membership in said group to other roles.
>
> Does this imply that an ADMIN role _must_ itself be a member
> of the group role it is to maintain membership of ?
>
> The question arises from a scenario where a DBA role would
> not need to be a member of a clinical group role but would
> be intended to maintain membership of clinical user roles
> within that group role.
>
> From a security point of view the question might be moot
> because an ADMIN role could always grant itself membership
> in the group role -- but it feels wrong for reasons of
> theoretical "correctness".
>
> IOW:
>
> - gm-dbo: user role for a DBA admin (not! superuser)
> - gm-bones: user role for a LLAP doctor
> - gm-doctors: group role for doctors, upon which are resting
> access permissions for clinical data
> - gm-bones is to be a member of gm-doctors in order to access clinical data
> - gm-dbo is intended to manage membership of gm-bones in gm-doctors
> - however, gm-dbo need not itself be a member of gm-doctors
>
> Is that possible within the current (as of PG 17) framework ?
Yes, that should work as follows:
test=# CREATE ROLE "gm-dbo" LOGIN;
CREATE ROLE
test=# CREATE ROLE "gm-bones";
CREATE ROLE
test=# CREATE ROLE "gm-doctors";
CREATE ROLE
test=# GRANT "gm-doctors" to "gm-dbo" WITH ADMIN TRUE, INHERIT FALSE, SET FALSE;
GRANT ROLE
test=# SET SESSION AUTHORIZATION "gm-dbo";
SET
test=> GRANT "gm-doctors" TO "gm-bones";
GRANT ROLE
test=> SET ROLE "gm-doctors";
ERROR: permission denied to set role "gm-doctors"
"gm-dbo" can manage membership in "gm-doctors" (ADMIN TRUE), but does not inherit
the role's privileges, nor can "gm-dbo" assume the identity of "gm-doctors".
Yours,
Laurenz Albe
