Established method to enable suid scripts?
kraduk at gmail.com
Fri May 13 08:32:54 UTC 2011
On 13 May 2011 08:32, Jonathan McKeown <j.mckeown at ru.ac.za> wrote:
> On Thursday 12 May 2011 17:26:49 Chris Telting wrote:
> > On 05/12/2011 07:57, Jonathan McKeown wrote:
> > >
> > > I'll say that again. It is inherently insecure to run an interpreted
> > > program set-uid, because the filename is opened twice and there's no
> > > guarantee that someone hasn't changed the contents of the file
> > > by that name between the first and second open.
> > >
> > > It's one thing to tell people they need to be careful with suid because
> > > it has security implications. Deliberately introducing a well-known
> > > security hole into the system would in my view be dangerous and wrong.
> > That race condition bug was fixed in ancient times. Before Freebsd or
> > Linux ever existed I believe. It's a meme that just won't die. People
> > accepted mediocrity in old commercial versions of Unix. I personally am
> > unsatisfied by kludges.
> That seems somewhat unlikely given, as someone else pointed out upthread,
> Perl still comes with a compile-time option SETUID_SCRIPTS_ARE_SECURE_NOW,
> suggesting that they often aren't. Yes, there are ways to avoid this race
> condition - the usual one is to pass a handle on the open file to the
> interpreter, rather than closing it and reopening it.
> This fix is not present in every Unix or Unix-like OS. In particular
> I'm happy to be corrected if I'm wrong) it's not present in FreeBSD, to the
> best of my knowledge. Whether there's a reason for that other than lack of
> developer time I don't know.
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what i cant understand is the complete aversion to sudo. Could you shed any
light on why you are trying to avoid a tried and tested method.
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