freebsd stable - Jul 2007 - regular user can destroy disk label?!?

Hello,

accidentally I did 'bsdlabel -w ar0s2' as unprivileged user but it was 
successfull.
Is this only possible because there was no mounted filesystem on it?
But I can imagine having data on unmounted filesystems.
Is it intended that regular useres can overwrite the label?
That's a big fault in my opinion.

Best regards,

-Harry

Harald Schmalzbauer wrote:
> Hello,
> 
> accidentally I did 'bsdlabel -w ar0s2' as unprivileged user but it
was
> successfull.
Likely you have a permissions problems.  Report result of 
	cd /dev ; ls -l  . ar0s2 ad0s2 /sbin/bsdlabel

On my 6.2-RELEASE for example I have an unwriteable combo of:
	dr-xr-xr-x   5 root  wheel          512 Jan  1  1970 ./
	crw-r-----  1 root  operator    0, 110 Jun 21 09:03 ad0s2
	crw-r-----  1 root  operator    0, 123 Jun 21 11:03 ad0s2a
	-r-xr-xr-x  2 root  wheel       233768 Apr 11 19:43 /sbin/bsdlabel*

Either:
  - You made a typo with ar0s2 & meant ad0s2,
  - Or you really mean "ar" - man 4 ar reports a comms card !
  - /dev/ar0s2 may be some meaningless normal file, not a device, but in
    /dev/ , writeable by you, from a previous mistake you made as root ?

> Is this only possible because there was no mounted filesystem on it?
No.
Regardless what the code of bsdlabel.c might try, if it doesnt have
SUID or SGID bits & isnt run as root, kernel won't allow it to write
what it doesnt have permission for.
> But I can imagine having data on unmounted filesystems.
Possible yes but see above.
> Is it intended that regular useres can overwrite the label?
No.
> That's a big fault in my opinion.
No such fault to fear :-)
BTW all above is general Unix philospohy, applies equally to Linux, *BSD
& commercial Unixes, ref. any book on Unix permissions etc :-)
> Best regards,
> 
> -Harry
Julian
-- 
Julian Stacey. Munich Computer Consultant, BSD Unix C Linux. http://berklix.com
 HTML mail unseen. Ihr Rauch=mein allergischer Kopfschmerz. Dump cigs 4 snuff.

Robert Watson wrote:
> On Wed, 4 Jul 2007, Julian H. Stacey wrote:
> 
> > Thomas Hurst wrote:
> >> * Julian H. Stacey (jhs@berklix.org) wrote:
> >>
> >>> Either:
> >>>   - You made a typo with ar0s2 & meant ad0s2,
> >>>   - Or you really mean "ar" - man 4 ar reports a
comms card !
> >>
> >> ataraid(4) exposes ATA RAID devices as ar%d:
> >>
> >>  -% man 4 ataraid |grep /dev
> >>       /dev/ar*  ATA RAID device nodes
> >
> > Thanks Thomas, that explains name then.
> >
> > It doesnt affect thoughts on permissions though, unless driver very
strange.
> 
> Something people occasional get surprised by is the fact that members of
the
> operator group are given significant access to local disks, etc.  Could
user
> account in question have been in the operator group?
> 
> Robert N M Watson
Good guess;  No response seen though from questioner Harald S.,
(though my mail filter was in heavy change this week).
BTW Harald S., Ian Smith wrote add -d: 		cd /dev ; ls -l -d . ar0s2

-- 
Julian Stacey. Munich Computer Consultant, BSD Unix C Linux. http://berklix.com
 HTML mail unseen. Ihr Rauch=mein allergischer Kopfschmerz. Dump cigs 4 snuff.