Re: CREATEROLE and role ownership hierarchies

> On Jan 31, 2022, at 8:53 AM, Stephen Frost <sfrost@snowman.net> wrote:
>
> Yeah, we do need to have a way to determine who is allowed to drop
> roles and role ownership seems like it's one possible approach to that.

Which other ways are on the table?  Having ADMIN on a role doesn't allow you to do that, but maybe it could?  What
else?

>> The main idea here is that having CREATEROLE doesn't give you ADMIN on roles, nor on role attributes.  For role
attributes,the syntax has been extended.  An excerpt from the patch's regression test illustrates some of that concept: 
>>
>> -- ok, superuser can create a role that can create login replication users, but
>> -- cannot itself login, nor perform replication
>> CREATE ROLE regress_role_repladmin
>>    CREATEROLE WITHOUT ADMIN OPTION     -- can create roles, but cannot give it away
>>    NOCREATEDB WITHOUT ADMIN OPTION     -- cannot create db, nor give it away
>>    NOLOGIN WITH ADMIN OPTION           -- cannot log in, but can give it away
>>    NOREPLICATION WITH ADMIN OPTION     -- cannot replicate, but can give it away
>>    NOBYPASSRLS WITHOUT ADMIN OPTION;   -- cannot bypassrls, nor give it away
>>
>> -- ok, superuser can create a role with CREATEROLE but restrict give-aways
>> CREATE ROLE regress_role_minoradmin
>>    NOSUPERUSER                         -- WITHOUT ADMIN OPTION is implied
>>    CREATEROLE WITHOUT ADMIN OPTION
>>    NOCREATEDB WITHOUT ADMIN OPTION
>>    NOLOGIN WITHOUT ADMIN OPTION
>>    NOREPLICATION                       -- WITHOUT ADMIN OPTION is implied
>>    NOBYPASSRLS                         -- WITHOUT ADMIN OPTION is implied
>>    NOINHERIT WITHOUT ADMIN OPTION
>>    CONNECTION LIMIT NONE WITHOUT ADMIN OPTION
>>    VALID ALWAYS WITHOUT ADMIN OPTION
>>    PASSWORD NULL WITHOUT ADMIN OPTION;
>
> Right, this was one of the approaches that I was thinking could work for
> managing role attributes and it's very similar to roles and the admin
> option for them.  As I suggested at least once, another possible
> approach could be to have login users not be able to create roles but
> for them to be able to SET ROLE to a role which is able to create roles,
> and then, using your prior method, only allow the attributes which that
> role has to be able to be given to other roles.

I'm not sure how that works.  If I have a group named "administrators" which as multiple attributes like BYPASSRLS and
such,and user "stephen" is a member of "administrators", then stephen can not only give away bypassrls to new users but
alsohas it himself.  How is that an improvement?  (I mean this as a question, not as criticism.) 

>  That essentially makes
> a role be a proxy for the per-attribute admin options.  There's pros and
> cons for each approach and so I'm curious as to which you feel is the
> better approach?  I get the feeling that you're more inclined to go with
> the approach of having an admin option for each role attribute (having
> written this WIP patch) but I'm not sure if that is because you
> contempltaed both and felt this was better for some reason or more
> because I wasn't explaining the other approach very well, or if there
> was some other reason.

I need more explanation of the other option you are contemplating.  My apologies if I'm being thick-headed.

>> -- fail, having CREATEROLE is not enough to create roles in privileged roles
>> SET SESSION AUTHORIZATION regress_role_minoradmin;
>> CREATE ROLE regress_nosuch_read_all_data IN ROLE pg_read_all_data;
>> ERROR:  must have admin option on role "pg_read_all_data"
>
> I would say not just privileged roles, but any roles that the user
> doesn't have admin rights on.

Yes, that's how it works.  But this portion of the test is only checking the interaction between CREATEROLE and
built-inprivileged roles, hence the comment. 

>> Whether "WITH ADMIN OPTION" or "WITHOUT ADMIN OPTION" is implied hinges on whether the role is given CREATEROLE.
Thathackery is necessary to preserve backwards compatibility.  If we don't care about compatibility, I could change the
patchto make "WITHOUT ADMIN OPTION" implied for all attributes when not specified. 
>
> Given the relative size of the changes we're talking about regarding
> CREATEROLE, I don't really think we need to stress about backwards
> compatibility too much.

Yeah, I'm leaning pretty strongly that way, too.

—
Mark Dilger
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