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Date: Sat, 16 Jan 2010 20:58:27 -0800
Message-ID: <551280e51001162058n52ee94b7v5ccb10d80284bc@mail.gmail.com>
Subject: Re: disablenetwork (v5): Require CAP_SETPCAP to enable
From: "Andrew G. Morgan" <morgan@kernel.org>
To: Michael Stone <michael@laptop.org>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
       linux-security-module@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
       David Lang <david@lang.hm>, Oliver Hartkopp <socketcan@hartkopp.net>,
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       Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
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       "C. Scott Ananian" <cscott@cscott.net>,
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       "Eric W. Biederman" <ebiederm@xmission.com>,
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       Randy Dunlap <randy.dunlap@oracle.com>,
       =?ISO-8859-1?Q?Am=E9rico_Wang?= <xiyou.wangcong@gmail.com>,
       Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
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       "Serge E. Hallyn" <serue@us.ibm.com>, Pavel Machek <pavel@ucw.cz>,
       Al Viro <viro@zeniv.linux.org.uk>, Kyle Moffett <kyle@moffetthome.net>
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On Sat, Jan 16, 2010 at 8:48 PM, Michael Stone <michael@laptop.org> wrote:
> Andrew Morgan wrote:
>>
>> Please use CAP_NET_ADMIN for this feature (and add the corresponding
>> comment in include/linux/capabilities.h).
>
> Sure.
> However, to make sure I understand the purpose of the adjustment, would you
> mind saying a word or two about what considerations cause you to recommend
> CAP_NET_ADMIN instead of (or in addition to?) CAP_SETPCAP?

If you take a look at the capabilities.h file, you'll see that each of
the capabilities is preceded by an explanation of what privilege it
enables.

CAP_SETPCAP refers to privileged manipulation of capabilities
(permission to violate the normal capability rules) and nothing to do
with the network.

You are adding something akin to a per-process tree firewall setting -
deny/enable network access to this process. I think you'll agree that
the CAP_NET_ADMIN description is a much better match for this.

Cheers

Andrew

>
> Thanks for your feedback,
>
> Michael
>
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