netdev - Re: Allow group ownership of TUN/TAP devices.

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Message-ID: <20090205105456.GA26440@bogon.ms20.nix>
Date:	Thu, 5 Feb 2009 11:54:57 +0100
From:	Guido Günther <agx@...xcpu.org>
To:	Michael Tokarev <mjt@....msk.ru>
Cc:	netdev <netdev@...r.kernel.org>
Subject: Re: Allow group ownership of TUN/TAP devices.

On Mon, Feb 02, 2009 at 05:18:53PM +0300, Michael Tokarev wrote:
[..snip..] 
> My first attempt - pretty obvious when I saw -g option of tunctl - is
> to add group ownership for the tun device and add a supplementary group
> to each user (their primary group should be different).  But that fails,
> since kernel only checks for egid, not any other group ids.
Since others tripped on this it might make sense to change it to also
check supplementary groups. However I don't think changing the existing
syscall is an option since it might allow users to access tun/tap
devices on existing systems that weren't allowed to do so before (which
might be a security problem).
Cheers,
 -- Guido
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