Problems with Cd permissions

Erik Postma epostma at nl.tue.win
Mon Sep 8 05:59:17 PDT 2003


On Mon, 8 Sep 2003 15:11:40 +0200, Nicolas FRANCOIS (AKA El Bofo)
<nicolas.francois at free.fr> wrote:
> Le Mon, 8 Sep 2003 11:22:05 +0200 Erik Postma <epostma at nl.tue.win> a
> écrit:
> 
> > On Mon, 8 Sep 2003 13:12:31 +0200, Nicolas FRANCOIS (AKA El Bofo)
> > <nicolas.francois at free.fr> wrote:
> > > I have two problems concerning my CD :
> > > 
> > > - When I first try to mount a data CD, i have to be root. After this
> > > first mount (ou unmount, for the CD is then root-owned), I can use
> > > it under my user account.
> > > - Same problem with wmrack (an Windowmaker applet to read audio CD)
> > > : first time I put an audio CD, I have to be root, launch wmrack,
> > > kill it, then I can do anything under user account.
> > > 
> > > Can you help me in this problem ?
> > > 
> > 
> > What messages show up in syslog
> > * if you try to mount it as regular user, but fail because you haven't
> > done so as root first;
> 
> Sep  8 15:08:40 detritus kernel: SCSI subsystem driver Revision: 1.00
> Sep  8 15:08:40 detritus kernel: Uniform CD-ROM driver unloaded
> Sep  8 15:08:40 detritus insmod:
> /lib/modules/2.4.20/kernel/drivers/cdrom/cdrom.o: pre-install sr_mod
> failed
> Sep  8 15:08:40 detritus insmod:
> /lib/modules/2.4.20/kernel/drivers/cdrom/cdrom.o: insmod block-major-11
> failed
> Sep  8 15:08:40 detritus kernel: SCSI subsystem driver Revision: 1.00
> Sep  8 15:08:40 detritus insmod:
> /lib/modules/2.4.20/kernel/drivers/cdrom/cdrom.o: pre-install sr_mod
> failed
> Sep  8 15:08:40 detritus insmod:
> /lib/modules/2.4.20/kernel/drivers/cdrom/cdrom.o: insmod block-major-11
> failed
> Sep  8 15:08:40 detritus kernel: Uniform CD-ROM driver unloaded

Indeed Simon was right: mounting requires loading the module cdrom, which
tries to load the module sr_mod first. That doesn't work for some reason.
Do you have any lines in /etc/modules.conf pertaining to cdrom or sr_mod
now? If yes, what are they? If no, try Simons suggestions: add the two
lines in his message to your /etc/modules.conf file and try again. (To
answer your implicit question: this does not entail any additional
security risks -- unless you have a specific reason not to trust any of
the involved kernel modules, in which case it's better to leave your cdrom
player alone!)

To simulate the behaviour of before accessing the thing as root, it may be
sufficient to do
 rmmod ide-scsi
 rmmod sr_mod
 rmmod sg
 rmmod cdrom
(or a subset of those commands) as root; maybe you don't need to reboot
then.

-- 
Erik Postma (Email: reverse the order of nl, tue and win.)



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