Re: silent semantic changes with reiser4

Christoph Hellwig
2004-08-26T15:57:55Z

On Thu, Aug 26, 2004 at 02:48:12PM +0100, Jamie Lokier wrote:
> > the current reiser4 semantics break that and as soon as you're having a
> > world-writeable (e.g. /tmp) dir on it and someone is doing an opendir
> > on it he's lost.
>
> How does the current reiser4 semantics break that?
>
> In a reiser4 filesystem, a file _is_ a directory.
> opendir() is supposed to succeed on it.
>
> There's bound to be some security issue, but I'm not sure what you're
> getting at with /tmp. What sort of sort of security problem arises
> with a world-writeable directory such as /tmp, that cannot arise with
> the standard fs semantics?

Actually you are right on that issue because it would open the
device/fifo as directory and not device/fifo (in fact I'd had to look at
the code again to see whether they actually do this only for files or
also for special files)