Re: Protection from SQL injection

On Wed, Apr 30, 2008 at 10:58 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> "Gurjeet Singh" <singh(dot)gurjeet(at)gmail(dot)com> writes:
> > Maybe we can extend the SQL's WITH clause do declare the constant along
> with
> > the query, and not separate from the query.
>
> > WITH CONSTANT c_jobrole = 'clerk', CONSTANT c_dept = 10
> > SELECT * FROM emp WHERE jobrole = c_jobrole and deptno = c_dept;
>
> [ scratches head... ] And that will provide SQL injection protection how?

Well, if the the query was:

WITH CONSTANT c_jobrole = <value from a FORM text field>, CONSTANT c_dept =
10
SELECT * FROM emp WHERE jobrole = c_jobrole and deptno = c_dept;

And if the attack supplied a value 'clerk OR 1=1' the final query (after
replacing constants) would look like this:

SELECT * FROM emp WHERE jobrole = 'clerk OR 1=1' and deptno = 10;

The attacker was not able to inject any new code there.

(reiterates: and let postgres allow literals only in the WITH clause)

>
> Anyway, you hardly need new syntax to do that, I'd expect
>
> WITH SELECT 'clerk' AS c_jobrole ...
>
> to accomplish it just fine.
>

I am not sure I understood this example.

Best regards,

--
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