Re: Trouble with v16 new CREATEROLE semantic

Hi,

On 15.02.2024 20:07, Dominique Devienne wrote:
> And now with V16.1 ===========================

> ddevienne=> create role zowner nologin createrole; -- owner of app's
> schemas and manager of related roles
> CREATE ROLE

> ddevienne=> set role zowner;
> ERROR:  permission denied to set role "zowner"
> ddevienne=> select roleid::regrole::text, member::regrole::text,
> grantor::regrole::text, admin_option, set_option, inherit_option from
> pg_auth_members where roleid::regrole::text like 'z%' or
> member::regrole::text like 'z%';
>  roleid |  member   | grantor  | admin_option | set_option |
> inherit_option
> --------+-----------+----------+--------------+------------+----------------
>  zowner | ddevienne | postgres | t            | f          | f
> (1 row)

You can use new psql command \drg for this query.

> (2 rows)
> ddevienne=> set role zowner;
> SET
> ddevienne=> create role zadmin nologin noinherit in role zowner; --
> means to become zowner explicitly
> ERROR:  permission denied to grant role "zowner"
> DETAIL:  Only roles with the ADMIN option on role "zowner" may grant
> this role.
> ddevienne=>
>
> So first surprise in V16. Despite having admin_option, from being the
> creator of the zowner role, I can't SET ROLE to it. I have to
> explicitly add the SET privilege.

Yes, but you can automate it with setting new parameter createrole_self_grant.

postgres(at)demo=# create role ddevienne login createrole;
CREATE ROLE
postgres(at)demo=# alter role ddevienne set createrole_self_grant = 'INHERIT, SET';
ALTER ROLE
postgres(at)demo=# \c - ddevienne
You are now connected to database "demo" as user "ddevienne".
ddevienne(at)demo=> create role zowner nologin createrole;
CREATE ROLE
ddevienne(at)demo=> \drg ddevienne
List of role grants
Role name | Member of | Options | Grantor
-----------+-----------+--------------+-----------
ddevienne | zowner | INHERIT, SET | ddevienne
ddevienne | zowner | ADMIN | postgres
(2 rows)

ddevienne(at)demo=> set role zowner;
SET

> And then, when ddevienne SET ROLE's to zowner, and tries to create
> zadmin *and* add it at the same time as a member of zowner (the
> current_role), it fails.
>
> So it looks like, despite ddevienne having admin_option on zowner,
> because it is on a "different line" than the set_option, it still
> cannot add members in zowner???

Behaviorchanged <https://github.com/postgres/postgres/commit/79de9842> for security reasons in v15. From Release Notes:
    > Remove the default ADMIN OPTION privilege a login role has on its own role membership (Robert Haas)
    > Previously, a login role could add/remove members of its own role, even without ADMIN OPTION privilege.

Zowner can create zadmin, but no way to grant membership in itself.

What you can do is create a role zadmin by ddevienne:

ddevienne(at)demo=> reset role;
RESET
ddevienne(at)demo=> create role zadmin nologin noinherit;
CREATE ROLE
ddevienne(at)demo=> grant zowner to zadmin with inherit true, set true;
GRANT ROLE
ddevienne(at)demo=> \drg zadmin
List of role grants
Role name | Member of | Options | Grantor
-----------+-----------+--------------+-----------
zadmin | zowner | INHERIT, SET | ddevienne
(1 row)

--
Pavel Luzanov
Postgres Professional:https://postgrespro.com