On Fri, Jul 01, 2005 at 12:45:22PM +0200, Miklos Szeredi wrote:
> > >
> > > Here's a description of a theoretical DoS scenario:
> > >
> > > http://marc.theaimsgroup.com/?l=linux-fsdevel&m=111522019516694&w=2
> >
> > So the open() hangs indefinately. but what if blackhat tries to install
> > a package from a no longer existing server on /net or via NFS?
> >
> > A user supplied pathname is not to be trusted by any setuid (or full
> > root) program.
>
> If /net won't detect a dead server within a timeout, I think it can be
> considered broken.
>
> > Another example: I'm not sure if there are still /dev/tty devices which
> > may block indefinately upon open() but:
> >
> > - I have yet to see a setuid program which always uses O_NONBLOCK
> > when opening user supplied pathnames.
> > - one cannot stat() and then open() because that gives a race.
>
> Is "being already broken" an excuse for preventing future breakage,
> when these are fixed?
All this breakage points into the same direction: A user supplied pathname
is not to be trusted by any setuid (or full root) program.
--
Frank
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