Re: WIP patch (v2) for updatable security barrier views

> > AFAICS the only area of objection is the handling of inherited
> > relations, which occurs within the planner in the current patch. I can
> > see that would be a cause for concern since the planner is pluggable
> > and it would then be possible to bypass security checks. Obviously
> > installing a new planner isn't trivial, but doing so shouldn't cause
> > collateral damage.
>
> FWIW, I don't see any way _not_ to do that in RLS. If there are security
> quals on a child table, they must be added, and that can only happen once
> inheritance expansion happens. That's in the planner.
>
> I don't see it as acceptable to ignore security quals on child tables, and
> if we can't, we've got to do some work in the planner.
>
> (I'm starting to really loathe inheritance).
>
Let me ask an elemental question. What is the reason why inheritance
expansion logic should be located on the planner stage, not on the tail
of rewriter?
Reference to a relation with children is very similar to reference of
multiple tables using UNION ALL. Isn't it a crappy idea to move the
logic into rewriter stage (if we have no technical reason here)?

Thanks,
--
NEC OSS Promotion Center / PG-Strom Project
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>

> -----Original Message-----
> From: pgsql-hackers-owner(at)postgresql(dot)org
> [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Craig Ringer
> Sent: Tuesday, January 28, 2014 12:35 PM
> To: Simon Riggs; Dean Rasheed
> Cc: Kaigai, Kouhei(海外, 浩平); Tom Lane; PostgreSQL Hackers; Kohei KaiGai;
> Robert Haas
> Subject: Re: [HACKERS] WIP patch (v2) for updatable security barrier views
>
> On 01/28/2014 12:09 AM, Simon Riggs wrote:
> > On 27 January 2014 15:04, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> wrote:
> >
> >> So for example, when planning the query to update an inheritance
> >> child, the rtable will contain an RTE for the parent, but it will not
> >> be referenced in the parse tree, and so it will not be expanded while
> >> planning the child update.
> >
> > Am I right in thinking that we have this fully working now?
>
> I haven't found any further problems, though I've been focusing more on
> reworking RLS on top of it.
>
> > AFAICS the only area of objection is the handling of inherited
> > relations, which occurs within the planner in the current patch. I can
> > see that would be a cause for concern since the planner is pluggable
> > and it would then be possible to bypass security checks. Obviously
> > installing a new planner isn't trivial, but doing so shouldn't cause
> > collateral damage.
>
> FWIW, I don't see any way _not_ to do that in RLS. If there are security
> quals on a child table, they must be added, and that can only happen once
> inheritance expansion happens. That's in the planner.
>
> I don't see it as acceptable to ignore security quals on child tables, and
> if we can't, we've got to do some work in the planner.
>
> (I'm starting to really loathe inheritance).
>
> > We have long had restrictions around updateable views. My suggestion
> > from here is that we accept the restriction that we cannot yet have
> > the 3-way combination of updateable views, security views and views on
> > inherited tables.
>
> That prevents the use of updatable security barrier views over partitioned
> tables, and therefore prevents row-security use on inherited tables.
>
> That seems like a very big thing to close off. I'm perfectly happy having
> that limitation for 9.4, we just need to make it possible to remove the
> limitation later.
>
> > Most people aren't using inherited tables
>
> Again, because we (ab)use them for paritioning, I'm not sure they're as
> little-used as I'd like.
>
> > and people that are have
> > special measures in place for their apps. We won't lose much by
> > accepting that restriction for 9.4 and re-addressing the issue in a
> > later release.
>
> Yep, I'd be happy with that.
>
>
> --
> Craig Ringer http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Training & Services
>
>
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