> Tatsuo Ishii <ishii@postgresql.org> writes:
> > I looked into this more and I think I'm afraid the proposed solution
> > actually does not work for SQL functions. For example,
>
> > CREATE OR REPLACE FUNCTION foo(INTEGER, INTEGER) RETURNS INTEGER AS $$
> > SET search_path To pg_catalog,public;
> > SELECT mod($1,$2);
> > $$ LANGUAGE sql SECURITY DEFINER;
>
> > If an attacker creates public.mod() to do something bad and override
> > his search_path to public,pg_catalog before executing foo(), his
> > attack will succeed since calling to mod() is resolved in the plan
> > time thus it will be resolved to public.mod, rather than
> > pg_catalog.mod.
>
> True, because the SQL-function code runs parse analysis for the whole
> function body before executing any of it. We could fix it by doing
> parse-analyze/plan/execute one statement at a time, which would make
> SQL functions work more like multi-statement strings submitted by a
> client application. Just a day or two ago there was someone complaining
> that they couldn't create and use a temp table in the same SQL function,
> due to this same behavior; and I recall similar gripes in the past.
> Maybe it's time to change it.
>
> regards, tom lane
Ok. So bottom line would be "do not use SECURITY DEFINER SQL functions
unless you make every object including functions and operators into
schema-qualified one".
--
Tatsuo Ishii
SRA OSS, Inc. Japan
