Re: [RFC] Let non-root users eject their ipods?

[Jens Axboe <axboe@suse.de>]

On Tue, Dec 20 2005, Ben Collins wrote:
> On Tue, 2005-12-20 at 14:28 +0100, Jens Axboe wrote:
> > On Tue, Dec 20 2005, Ben Collins wrote:
> > > On Tue, 2005-12-20 at 08:46 +0100, Jens Axboe wrote:
> > > > On Mon, Dec 19 2005, john stultz wrote:
> > > > > All,
> > > > > 	I'm getting a little tired of my roommates not knowing how to safely
> > > > > eject their usb-flash disks from my system and I'd personally like it if
> > > > > I could avoid bringing up a root shell to eject my ipod. Sure, one could
> > > > > suid the eject command, but that seems just as bad as changing the
> > > > > permissions in the kernel (eject wouldn't be able to check if the user
> > > > > has read/write permissions on the device, allowing them to eject
> > > > > anything).
> > > > 
> > > > This just came up yesterday, eject isn't opening the device RDWR hence
> > > > you have a permission problem with a command requiring write
> > > > permissions. So just fix eject, there's no need to suid eject or run it
> > > > as root.
> > > 
> > > Yep, and here's the patch to do it:
> > > 
> > > http://bugzilla.ubuntu.com/attachment.cgi?id=5415
> > > 
> > > Still, this whole issue with ALLOW_MEDIUM_REMOVAL. Would be nice if
> > > CDROMEJECT just did the right thing.
> > 
> > I would tend to agree, but you are bypassing the checks that are in
> > there by doing so which isn't very nice. Then we might as well just mark
> > ALLOW_MEDIUM_REMOVAL as safe-for-read in the first place.
> 
> Should be an easy check to add. In fact, I'll resend both patches with
> that in place if you want.

There's still the quirky problem of forcing a locked tray out. In some
cases this is what you want, if things get stuck for some reason or
another. But usually the tray is locked for a good reason, because there
are active users of the device.

Say two processes has the cdrom open, one of them doing io (maybe even
writing!), the other could do a CDROMEJECT now and force the ejection of
a busy drive.

-- 
Jens Axboe

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