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Date:      Sat, 28 Apr 2012 19:02:14 -0400
From:      Jason Hellenthal <jhellenthal@dataix.net>
To:        Kurt Jaeger <lists@opsec.eu>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Restricting users from certain privileges
Message-ID:  <20120428230214.GA34324@DataIX.net>
In-Reply-To: <20120428180431.GP5335@home.opsec.eu>
References:  <CACuV5sCyCgn8aBawTEP=BT%2B%2B4Ut4kPt8fXSq%2BgcS2YrkZaU%2BJw@mail.gmail.com> <E1SO2ER-000K66-8k@kabab.cs.huji.ac.il> <CACuV5sCHmnUnXTTY%2BkGqszi-Ynu8Vr3bf%2BLALf=yQbhHPXSdXA@mail.gmail.com> <4F9BBABA.6040708@rdtc.ru> <0F37A1B9-993B-4A4E-9FCC-8B19AADCFB72@punkt.de> <20120428102117.GX37811@e-new.0x20.net> <20120428180431.GP5335@home.opsec.eu>

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On Sat, Apr 28, 2012 at 08:04:31PM +0200, Kurt Jaeger wrote:
> Hi!
> 
> > > > Please do study sudo real power :-)
> > > > It can give selective privileges per-command,
> [...]
> > > Just make sure none of the permitted commands has got the
> > > feature of starting a shell ;-))
> > 
> > Right, think of vi(1), less(1), et al.
> 
> Even this aspect is taken care of with sudo (at least to a certain limit):
> 
>        NOEXEC and EXEC
> 
>        If sudo has been compiled with noexec support and the underlying
>        operating system supports it, the NOEXEC tag can be used to prevent a
>        dynamically-linked executable from running further commands itself.
> 
>        In the following example, user aaron may run /usr/bin/more and
>        /usr/bin/vi but shell escapes will be disabled.
> 
>         aaron  shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
> 
>        See the "PREVENTING SHELL ESCAPES" section below for more details on
>        how NOEXEC works and whether or not it will work on your system.
> 

cp /usr/bin/vi ~/

or upload your own...

sudo $HOME/vi


You need to be very careful with this NOEXEC thinking as it will not
always get you what you originally intended.


-- 

 - (2^(N-1))



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