Rules <-> Functions <-> Permissions

Hi,

I'm trying create a SECURE TIER in my DB.

I need "dummys" tables that accept INSERTS from any users, then execute a
RULE that insert the datas into the REAL table. The REAL tables accept
INSERT only from "postgres user".

This work fine !

But when I need the RULE calls a FUNCTION (plpgsql) for more detailed data
manipulating, the FUNCTION runs with the normal user permissions, and not
with the RULE permissions.

Well, if a RULE calls the FUNCTION, the FUNCTION must run with the same
RULEs permissions ...

let-me show you.

----------------------------
\c - postgres
create table teste (codigo int4, nome varchar (30) );

create table teste2 (codigo int4, nome varchar (30) );
grant ALL on teste2 TO joe;

create rule teste2 as on insert to teste2 do insert into teste (codigo,nome)
values (new.codigo,new.nome);

\c - joe
insert into teste (codigo,nome) values (1,'tulio');
--> PERMISSION DENIED ! - OK

insert into teste2 (codigo,nome) values (1,'tulio');
--> INSERTS - OK

select * from teste2;
--> SHOW THE ROWS - OK

\c - postgres
select * from teste;
--> SHOW THE ROWS - OK

------------------------------------------------------------------------
In this example, all is OK, but ...

----------------------------
\c - postgres
create table teste (codigo int4, nome varchar (30) );

create table teste2 (codigo int4, nome varchar (30) );
grant ALL on teste2 TO joe;

create function teste (integer,text) returns integer as '
begin
insert into teste (codigo,nome) values ($1,$2);
end;' language 'plpgsql';

create rule teste2 as on insert to teste2 do select teste
(new.codigo::integer,new.nome::text);

\c - joe
insert into teste (codigo,nome) values (1,'tulio');
--> PERMISSION DENIED ! - OK

insert into teste2 (codigo,nome) values (1,'tulio');
--> PERMISSION DENIED ON TESTE =============================>> NOT OK

------------------------

Sorry my English..... Do you undestand ??

Could you help-me ?
I realy need make HEAVY consistencys, and I need a FUNCTION ...