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From: Andy Lutomirski <luto@amacapital.net>
Date: Fri, 24 Apr 2015 15:55:08 -0700
Message-ID: <CALCETrUdNp18ZeOC8pRYn_YPUp8nFyH7aS+dFoBf34XNmER-nA@mail.gmail.com>
Subject: Re: [RFC] capabilities: Ambient capabilities
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        "Ted Ts'o" <tytso@mit.edu>, "Andrew G. Morgan" <morgan@kernel.org>,
        Andrew Morton <akpm@linuxfoundation.org>,
        Serge Hallyn <serge.hallyn@ubuntu.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Linux API <linux-api@vger.kernel.org>,
        Austin S Hemmelgarn <ahferroin7@gmail.com>,
        linux-security-module <linux-security-module@vger.kernel.org>,
        Aaron Jones <aaronmdjones@gmail.com>, Christoph Lameter <cl@linux.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        Markku Savela <msa@moth.iki.fi>, Kees Cook <keescook@chromium.org>,
        Jonathan Corbet <corbet@lwn.net>
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On Apr 24, 2015 2:15 PM, "Serge E. Hallyn" <serge@hallyn.com> wrote:
>
> On Fri, Apr 24, 2015 at 01:18:44PM -0700, Andy Lutomirski wrote:
> > On Fri, Apr 24, 2015 at 1:13 PM, Christoph Lameter <cl@linux.com> wrote:
> > > On Fri, 24 Apr 2015, Andy Lutomirski wrote:
> > >
> > >> 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?
> > >
> > > Yes but you seem to be just adding one additional step without too much of
> > > a benefit because you still need CAP_SETPCAP.
> > >
> >
> > No, because I set the default to on :)
>
> Right - I definately prefer
>
> . default off
> . CAP_SETPCAP required to turn it on (for self and children)
> . once on, anyone can copy bits from (whatever we decided) to pA.
>

Why default off?  If there's some weird reason that switching it on
could cause a security problem, then I'd agree, but I haven't spotted
a reason yet.

--Andy
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