Date: Tue, 03 Jul 2007 13:13:38 +0200 From: "Julian H. Stacey" <jhs@berklix.org> To: Harald Schmalzbauer <h.schmalzbauer@omnisec.de> Cc: freebsd-stable@freebsd.org Subject: Re: regular user can destroy disk label?!? Message-ID: <200707031113.l63BDcZW036403@fire.js.berklix.net> In-Reply-To: <200707031127.07413.h.schmalzbauer@omnisec.de> References: <200707031127.07413.h.schmalzbauer@omnisec.de>
next in thread | previous in thread | raw e-mail | index | archive | help
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.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200707031113.l63BDcZW036403>