Re: Re: Missing REVOKE in SQL for functions with SECURITY DEFINER (or any function, really)

Hi Dave,

Please find attached the patch that fixes this issue related to security
definer not provided.

According to our discussion based on
http://www.postgresql.org/docs/9.2/static/sql-grant.html the fix that I
have made is as follows:

When a user creates a new function, database or language, we show their
default privileges in the dialog box, thus giving the user a chance to
revoke them if they wish to. If the user chooses to revoke them, then in
the reverse engineered code in the sql pane, the revoke statement will be
visible. For this I have modified the GetGrant function of pgObject to
handle this.

Thus we ourselves don't revoke the default grant given to function,
database or language object, but we make sure that they are visible to the
user, so that he/she can take an informed decision.

In this patch I have also taken care that if the owner of an object revokes
all privileges from himself, then that should also be seen in the reverse
engineered sql in the sql pane.

Let me know your views on this patch.

Thanks,

On Mon, Apr 8, 2013 at 5:08 PM, Dave Page <dpage(at)pgadmin(dot)org> wrote:

> Dhiraj, can you look into this please?
>
> Thanks.
>
> On Sun, Apr 7, 2013 at 11:02 PM, Erwin Brandstetter
> <brandstetter(at)falter(dot)at> wrote:
> > Hi developers!
> >
> > I have been missing in action for a while, so I am not sure whether
> anybody
> > even uses trac any more.
> > Either way, I just ran into this bug once again and checked to find it
> still
> > open:
> > http://code.pgadmin.org/trac/ticket/88
> >
> > Basically, REVOKE EXECUTE ON FUNCTION is omitted in the DDL script.
> > To reproduce:
> >
> > CREATE OR REPLACE FUNCTION foo() RETURNS int AS 'SELECT 1' LANGUAGE sql;
> > REVOKE EXECUTE ON FUNCTION foo() FROM public;
> >
> > This is a **potential security hazard** and it has been open for (at
> least)
> > over a year now.
> >
> > Regards
> > Erwin
> >
> >
> >
> > On 27.02.2012 23:53, Erwin Brandstetter wrote:
> >
> > On 27.02.2012 23:38, Erwin Brandstetter wrote:
> >
> > Hi developers!
> >
> > Congratulations on the many bug fixes in the latest release!
> > I think I found another serious problem.
> >
> > Testing with pgAdmin 1.14.2 on Windows XP. Server is PostgreSQL 9.1 on
> > Devian Squeeze.
> >
> > There is a security hazard lingering in the reverse engineered SQL of the
> > latest version 1.14.2 (and versions before it).
> >
> > As summed up here
> >
> >
> http://www.postgresql.org/docs/current/interactive/sql-createfunction.html#SQL-CREATEFUNCTION-SECURITY
> > the execute privilege is granted to PUBLIC by default. It needs to be
> > revoked for security critical functions.
> >
> > I quote the manual:
> >
> > Another point to keep in mind is that by default, execute privilege is
> > granted to PUBLIC for newly created functions (see GRANT for more
> > information). Frequently you will wish to restrict use of a security
> definer
> > function to only some users. To do that, you must revoke the default
> PUBLIC
> > privileges and then grant execute privilege selectively.
> >
> >
> > This goes wrong with pgAdmin 1.14.2. Consider this test case, executed as
> > superuser postgres:
> >
> > CREATE OR REPLACE FUNCTION foo ()
> > RETURNS void AS
> > $BODY$
> > BEGIN
> > PERFORM 1;
> > END;
> > $BODY$
> > LANGUAGE plpgsql VOLATILE SECURITY DEFINER;
> > ALTER FUNCTION foo() SET search_path=public, pg_temp;
> > REVOKE ALL ON FUNCTION foo() FROM PUBLIC;
> > GRANT EXECUTE ON FUNCTION foo() TO ief;
> >
> >
> > The reverse engineered SQL looks like this
> >
> > -- Function: foo()
> >
> > -- DROP FUNCTION foo();
> >
> > CREATE OR REPLACE FUNCTION foo()
> > RETURNS void AS
> > $BODY$
> >
> > BEGIN
> > PERFORM 1;
> > END;
> > $BODY$
> > LANGUAGE plpgsql VOLATILE SECURITY DEFINER
> > COST 100;
> > ALTER FUNCTION foo() SET search_path=public, pg_temp;
> >
> > ALTER FUNCTION foo()
> > OWNER TO postgres;
> > GRANT EXECUTE ON FUNCTION foo() TO postgres;
> > GRANT EXECUTE ON FUNCTION foo() TO ief;
> >
> >
> > The REVOKE statement is missing, which is a serious security hazard. A
> > recreated function will be open to the the public.
> >
> > Regards
> > Erwin
> >
> >
> > I reopened ticket #88 for that
> > http://code.pgadmin.org/trac/ticket/88#comment:2
> > because it seemed closely related.
> >
> > Regards
> > Erwin
> >
> >
> >
>
>
>
> --
> Dave Page
> Blog: http://pgsnake.blogspot.com
> Twitter: @pgsnake
>
> EnterpriseDB UK: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>

--
regards,

*Dhiraj Chawla*
Software Engineer
EnterpriseDB Corporation
The Enterprise PostgreSQL Company

Phone: +91-20-30589522