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Date:      Fri, 30 Mar 2012 22:16:22 +0200
From:      "Julian H. Stacey" <jhs@berklix.com>
To:        Adrian Chadd <adrian@freebsd.org>
Cc:        arch@freebsd.org
Subject:   Re: Should standard binaries & directories revert from uid=root to bin ? 
Message-ID:  <201203302016.q2UKGMHP016165@fire.js.berklix.net>
In-Reply-To: Your message "Fri, 30 Mar 2012 11:57:29 PDT." <CAJ-Vmon=YKcW6Osn2TXcJDbNH1B0xLapL-fTz0myGanHdPW4Yw@mail.gmail.com> 

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Hi Adrian & arch@
Please don't top post to arch@freebsd.org
Please don't emit messy quoted-printable hex. '\xa0' for clean spaces.

Adrian Chadd wrote:
> hi,
> 
> because id=0 defaults to being squashed via nfs.

Not a sentence.  Please clarify.


> But if you have a
> filesystem full of uid=bin/gid=bin binaries, a slightly insecure NFS
> setup would allow NFS clients to simply set their uid=bin and change
> these binaries. :-)

I don't understand your meaning. I do understand SUID though.
Please clarify whay you mean.

Do you mean if something like /usr/sbin/lpd was uid=bin on one
system, it might slip via a bad NFS to be seen as UID=0 on another ?
& remotely excutable on 2nd system as a UID=0 ? 
If that's what you mean, bear in mind /usr/sbin/lpd is currently already
uid=0.  Also bear in mind NFS man exports -maproot

Are you stating? or just speculating ? if [flakey?] NFS was the
reason FreeBSD changed from bin to root ?

I hadn't considered NFS lax security when I asked the question.
  (I had merely mentioned NFS in context of explaining how I
  (re-)noticed the wholesale conversion from bin to root.

It's possible NFS might have been a reason ?
but I don't see you made an explanation [yet] as to how 
a return from root to bin would be dangerous with a flakey NFS ?

Not that I'm saying it would/ wouldn't be an issue,
I am just asking why we changed, & if a move back would be good ?
As I see one loss from the change.
There may have been other issues though ? Anyone know ?


> On 30 March 2012 08:16, Julian H. Stacey <jhs@berklix.com> wrote:
> > Hi arch@
> > Time was, (& I can go back over 25 years here, but more recently too :-)
> > When standard Unix non SUID executables such as wc would be UID=bin,
> > GID=bin, & not root.  Ditto bin/ & lib/ etc directories.
> >
> > One advantage was:
> >  Anything that showed up with ls -l as UID=0 was either a SUID
> >  special, known to the admin's eye, or some administrative dropping,
> >  mistakenly created by someone logged in as root, to be reviewed/
> >  regenerated/ deleted.
> >
> > Now all is UID=0.  Why ? What advantage did it bring ?
> >
> > Obviously some SUID & SGID executables need 0 (some could need just bin!)
> > but most files & directories do not need UID 0.
> >
> > BTW, How I noticed this :
> >  I was tracing why
> >        /usr/sbin/sshd -d -d -d -D
> >  was erroring:
> >        debug3: secure_filename: checking '/.amd_mnt/sshd_host/ad4s1/usr1/home'
> >        Authentication refused: bad ownership or modes for directory
> >                 /.amd_mnt/sshd_host/ad4s1/usr1/home
> >  just because my ~/.ssh was symbolicaly linked via AMD+NFS mounted on another
> >  host, & there an intermediate directory was owned by bin & not root,
> >        ls -la /host/sshd_host/ad4s1/usr1/home
> >                drwxr-xr-x  18 bin     bin       512 Mar  6 11:56 ./
> >  so I had to
> >        chown root:wheel /ad4s1/usr1/home
> >  Just to satisfy sshd being pointlessly strict, as directory was 755.
> >
> > So we have sshd that's pointlessly strict, & ownerships that seem
> > to have near all lost their precision. A funny combo ;-)
> >
> > Might others tackle the generic over use of root ?
> > If so I could create a patch to send-pr ssh  ?
> > (but as ssh is an import, maybe just report & not [yet?] patch ?)
> >
> > Cheers,
> > Julian
> > --
> > Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklixcom
> >  Reply below not above, cumulative like a play script, & indent with "> ".
> >  Format: Plain text. Not HTML, multipart/alternative, base64, quoted-printable.
> >        Mail from @yahoo dumped @berklix.  http://berklix.org/yahoo/
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> 


Cheers,
Julian
-- 
Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com
 Reply below not above, cumulative like a play script, & indent with "> ".
 Format: Plain text. Not HTML, multipart/alternative, base64, quoted-printable.
	Mail from @yahoo dumped @berklix.  http://berklix.org/yahoo/



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