Re: semaphore usage "port based"?

[ FreeBSD email list removed.]

I totally agree, and have added the attached documentation patch to
recommend using different users in FreeBSD jails.

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Stephen Frost wrote:
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> * Marc G. Fournier (scrappy(at)postgresql(dot)org) wrote:
> > On Mon, 3 Apr 2006, Stephen Frost wrote:
> > >Running the Postgres instances under different uids (as you'd probably
> > >expect to do anyway if not using the jails) is probably the right
> > >approach. Doing that and using jails would probably work, just don't
> > >delude yourself into thinking that you're safe from a malicious user in
> > >one jail.
> >
> > We don't ... we put all our databases on a central database server, even
> > private ones, that nobody has shell access to ... we keep them isolated
> > ...
>
> I guess what I was trying to get at is this:
>
> Running 2 Postgres instances under FreeBSD with (or without really, but
> I guess that's more obvious) jails but with the same UID is a bad idea.
> Even if Postgres could be modified to allow this to work you're going to
> be in a position where the jail isn't really helping much except to give
> a somewhat false (in this case) sense of security. We probably
> shouldn't encourage it and in fact it's something of a nice feature that
> it breaks.
>
> The reasoning is pretty simple: if someone manages to get control of
> one of the Postgres instances they're going to be able to wreck havoc on
> the other. With different UIDs, with or without jails, this would be
> much more difficult (need to get root first).
>
> Running 2 Postgres instances under FreeBSD with jails *and* different
> UIDs is *probably* better than w/o jails but since you have to enable
> the single-instance IPC system it might not be that great of a benefit
> over a simple chroot or similar.
>
> Hope that helps...
>
> Thanks,
>
> Stephen
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