Re: [HACKERS] Interest in a SECURITY DEFINER function current_userstack access mechanism? - Mailing list pgsql-hackers

From Nico Williams
Subject Re: [HACKERS] Interest in a SECURITY DEFINER function current_userstack access mechanism?
Date
Msg-id 20171018210759.GD4496@localhost
Whole thread Raw
In response to Re: [HACKERS] Interest in a SECURITY DEFINER function current_userstack access mechanism?  ("David G. Johnston" <david.g.johnston@gmail.com>)
Responses Re: [HACKERS] Interest in a SECURITY DEFINER function current_userstack access mechanism?
List pgsql-hackers
On Wed, Oct 18, 2017 at 01:43:30PM -0700, David G. Johnston wrote:
> Regardless of the merits of the proposed feature, the function
> "session_user" is SQL-defined and should not be modified or enhanced.
> 
> I could see "calling_role()" being useful - it returns the same value
> as "current_role" normally and in security invoker functions while in
> a security definer function it would return whatever current_role
> would have returned if the function was a security invoker (i.e., the
> role that the system will put back into effect once the security
> definer function returns).

That... could be awkward where lots of SECURITY DEFINER functions may be
user-callable, but also called from each other.  But it would be
minimally useful.

More useful than this, for me, would be a way to get the top-most user.

> Introducing the concept of a stack at the SQL level here seems, at
> first glance, to be over-complicating things.

Because of the current implementation of invocation of SECURITY DEFINER
functions, a stack is trivial to build, since it's a list of nodes
allocated on the C stack in fmgr_security_definer().

Nico
-- 


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers

pgsql-hackers by date:

Previous
From: Robert Haas
Date:
Subject: Re: [HACKERS] [COMMITTERS] pgsql: Fix traversal of half-frozen update chains
Next
From: "David G. Johnston"
Date:
Subject: Re: [HACKERS] Interest in a SECURITY DEFINER function current_userstack access mechanism?