Re: pg_shmem_allocations view

On 2014-08-18 12:27:12 -0400, Tom Lane wrote:
> Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> > On 2014-08-18 11:56:44 -0400, Robert Haas wrote:
> >> I fully agree with the idea of exposing the amount of free memory in
> >> the shared memory segment (as discussed in other emails); that's
> >> critical information. But I think exposing address space layout
> >> information is of much less general utility and, really, far too
> >> risky.
>
> > Meh. For one it's just the offsets, not the actual addresses. It's also
> > something you can relatively easily compute at home by looking at a
> > couple of settings everyone can see. For another, I'd be perfectly
> > content making this superuser only. And if somebody can execute queries
> > as superuser, address layout information really isn't needed anymore to
> > execute arbitrary code.
>
> I agree that this has to be superuser-only if it's there at all.
>
> Should we consider putting it into an extension rather than having
> it in the core system? That would offer some additional protection
> for production systems, which really shouldn't have much need for
> this IMO.

I'd considered that somewhere upthread and decided that it'd require
exposing to much internals from shmem.c/dsm.c without a corresponding
benefit.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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