Re: role self-revocation - Mailing list pgsql-hackers

From David G. Johnston
Subject Re: role self-revocation
Date
Msg-id CAKFQuwbmx9bSu6iob-k88APFZtzvPVmXFjAjdR0u3MqR3TWzzg@mail.gmail.com
Whole thread Raw
In response to Re: role self-revocation  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: role self-revocation  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Sun, Mar 6, 2022 at 8:19 AM Robert Haas <robertmhaas@gmail.com> wrote:
The choice of names in my example wasn't accidental. If the granted
role is a login role, then the superuser's intention was to vest the
privileges of that role in some other role, and it is surely not right
for that role to be able to decide that it doesn't want it's
privileges to be so granted. That's why I chose the name "peon".

 >> rhaas [as peon] => revoke peon from boss; -- i don't like being bossed around!

Well, the peon is not getting bossed around, the boss is getting peoned around and the peon has decided that they like boss too much and don't need to do that anymore.

When you grant a group "to" a role you place the role under the group - and inheritance flows downward.

In the original thread Stephen wrote:

"This is because we allow 'self administration' of roles, meaning that
they can decide what other roles they are a member of.:

The example, which you moved here, then attempts to demonstrate this "fact" but gets it wrong.  Boss became a member of peon so if you want to demonstrate self-administration of a role's membership in a different group you have to login as boss, not peon.  Doing that, and then revoking peon from boss, yields "ERROR: must have admin option on role "peon"".

So no, without "WITH ADMIN OPTION" a role cannot decide what other roles they are a member of.

I don't necessarily have an issue changing self-administration but if the motivating concern is that all these new pg_* roles we are creating are something a normal user can opt-out of/revoke that simply isn't the case today, unless they are added to the pg_* role WITH ADMIN OPTION.

That all said, permissions SHOULD BE strictly additive.  If boss doesn't want to be a member of pg_read_all_files allowing them to revoke themself from that role seems like it should be acceptable.  If there is fear in allowing someone to revoke (not add) themselves as a member of a different role that suggests we have a design issue in another feature of the system.  Today, they neither grant nor revoke, and the self-revocation doesn't seem that important to add.

David J.



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