Re: ROLE INHERIT

Tom Lane wrote:
> "David Legault" <legault(dot)david(at)gmail(dot)com> writes:
>
>> I thought it would transfer that CREATEROLE privilege too.
>>
>
>

I've been dying to get 2 cents in on this. Tell me if this suggestion
makes any sense.

We use real database users in our systems, we don't connect in with an
over-endowed user and then arbitrate security in client code.
Therefore, we depend entirely upon the server's ability to enforce security.

The practical advantage of this, which is huge, is that nowhere in my
Postgres settings do I have to make allowance for the web user (apache)
to "go root" with respect to Postgres. As a general rule we consider
this good of course, because a remote exploit on the web server could
not do anything the user could not do anyway.

Except for the hole. On a public site that lets users register, we have
to have way to let the web server assume the role of somebody who has
createuser privelege, and that's pretty much the end of the no-root
policy. If an exploit could be placed, it could simply go into that
mode and create a superuser.

What would be really nice is if you could limit the ability of
CREATEUSER to grant roles. A nice general solution would be to allow a
user with CREATEUSER privelege to only put other users into the same
groups that person is in, or perhaps into a list specified by a
higher-privelege user.

What's chances of anything like that showing up?

And, dumb question, am I mistaking the purpose of INHERIT and it already
does what I'm saying? I don't think so because INHERIT does not let
somebody create users out of the void.

> This is documented someplace ... ah, under CREATE ROLE:
>
> : The INHERIT attribute governs inheritance of grantable privileges (that
> : is, access privileges for database objects and role memberships). It
> : does not apply to the special role attributes set by CREATE ROLE and
> : ALTER ROLE. For example, being a member of a role with CREATEDB
> : privilege does not immediately grant the ability to create databases,
> : even if INHERIT is set; it would be necessary to become that role via
> : SET ROLE before creating a database.
>
> The main reason we did that is that SUPERUSER seemed a bit too dangerous
> to be an inheritable privilege. You could argue the other role
> attribute bits either way, but for simplicity they all act the same.
>
> regards, tom lane
>
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