Re: PATCH: cdrecord: avoiding scsi device numbering for ide devices

Christer Weinigel
2004-08-22T17:32:07Z

Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> On Sul, 2004-08-22 at 17:33, Christer Weinigel wrote:
> > Regarding the current 2.6.8 kernel, wouldn't it be a better idea to
> > move the CAP_SYS_RAWIO check to open time instead of when the ioctl is
> > called? This would require a new flag somewhere in the file structure
> > I suppose, e.g. file->f_mode & FMODE_RAWIO.
>
> This leads to all sorts of bugs where descriptors owned by one process
> are given to another less priviledged one. In the networking world
> similar logic led to holes because rsh for example gave root opened fd's
> to users.

On the other hand a bug in my favourite cd burner application could
give away SYS_CAP_RAWIO instead, and I think that is even worse.

Besides, checking SYS_CAP_RAWIO at open time is the way /dev/mem
works. OTOH applications don't normally hand over /dev/mem to other
applications I suppose.

I'm just tossing ideas around, please ignore me if they are stuipd :-)

/Christer

--
"Just how much can I get away with and still go to heaven?"

Freelance consultant specializing in device driver programming for Linux
Christer Weinigel <christer@weinigel.se> http://www.weinigel.se