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From: Andy Lutomirski <luto@amacapital.net>
Date: Fri, 24 Apr 2015 12:53:47 -0700
Message-ID: <CALCETrV7S0dLkNWMSYsL7MFuLgdpQwUEAjW6zTwRE8uhh_AuBQ@mail.gmail.com>
Subject: Re: [RFC] capabilities: Ambient capabilities
To: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Christoph Lameter <cl@linux.com>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Andrew Lutomirski <luto@kernel.org>, "Ted Ts'o" <tytso@mit.edu>,
        Andrew Morton <akpm@linuxfoundation.org>,
        "Andrew G. Morgan" <morgan@kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Austin S Hemmelgarn <ahferroin7@gmail.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Aaron Jones <aaronmdjones@gmail.com>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        LKML <linux-kernel@vger.kernel.org>, Markku Savela <msa@moth.iki.fi>,
        Kees Cook <keescook@chromium.org>, Jonathan Corbet <corbet@lwn.net>
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On Fri, Apr 24, 2015 at 12:09 PM, Serge Hallyn <serge.hallyn@ubuntu.com> wrote:
> Quoting Andy Lutomirski (luto@amacapital.net):
>> On Fri, Apr 24, 2015 at 10:53 AM, Serge Hallyn <serge.hallyn@ubuntu.com> wrote:
>> > Quoting Christoph Lameter (cl@linux.com):
>> >> On Thu, 9 Apr 2015, Christoph Lameter wrote:
>> >>
>> >> > > I'll submit a new version this week with the securebits.  Sorry for the delay.
>> >>  > Are we going to get a new version?
>> >>
>> >> Replying to my own here. Cant we simply use the SETPCAP approach as per
>> >> the patch I posted?
>> >
>> > Andy had objections to that, but it seems ok to me.
>> >
>>
>> I object because CAP_SETPCAP is very powerful whereas
>> CAP_NET_BIND_SERVICE, for example, isn't.  I'm fine with having a
>> switch to turn off ambient caps, but requiring the "on" state to give
>
> Would only really be needed for the initial 'enable ambient caps for this
> process tree', though.  Once that was set, add/remove'ing caps from the
> ambient set wouldn't need to be required.

That's sort of what my patch does -- you need CAP_SETPCAP to switch
the securebit.

But Christoph's patch required it to add caps to the ambient set, right?

--Andy
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