Date: Thu, 26 Feb 2015 12:28:30 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
To: "Serge E. Hallyn" <serge@hallyn.com>
cc: Serge Hallyn <serge.hallyn@ubuntu.com>,
        Serge Hallyn <serge.hallyn@canonical.com>,
        Andy Lutomirski <luto@amacapital.net>,
        Aaron Jones <aaronmdjones@gmail.com>, "Ted Ts'o" <tytso@mit.edu>,
        linux-security-module@vger.kernel.org, akpm@linuxfoundation.org,
        "Andrew G. Morgan" <morgan@kernel.org>,
        Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Austin S Hemmelgarn <ahferroin7@gmail.com>,
        Markku Savela <msa@moth.iki.fi>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Jonathan Corbet <corbet@lwn.net>
Subject: Re: [PATCH] capabilities: Ambient capability set V1
In-Reply-To: <20150226153524.GC15182@mail.hallyn.com>
Message-ID: <alpine.DEB.2.11.1502261224580.7451@gentwo.org>
References: <20150223164623.GB32181@mail.hallyn.com> <alpine.DEB.2.11.1502231049110.21926@gentwo.org> <20150223181553.GE25477@ubuntumail> <20150224051928.GA14755@mail.hallyn.com> <20150224154715.GA20682@mail.hallyn.com> <alpine.DEB.2.11.1502240956400.29006@gentwo.org>
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On Thu, 26 Feb 2015, Serge E. Hallyn wrote:

> > Well doing that breaks su.
>
> Don't what exactly?  You're saying that doing
>
> pI' = pI
> pA' = pA  (pA is ambient)
> pP' = (X & fP) | (pI & (fI | pA))
> pE' = pP' & (fE | pA)
>
> stopped su from having CAP_SETGID while
>
> pI' = pI
> pA' = pA  (pA is ambient)
> pP' = (X & fP) | (pI & (fI | pA))
> pE' = pP' & fE
>
> worked?  I'll hope you're saying both "fail", in which case

fE does not exist in cpu_vfs_cap_data. We only get fI and fP. Why in the
world does setcap allow setting fE?

V1 does not use fE. In my newer attempt, I seemed to have worked
with zeroed field that I assumed was filled in.

I will just do

pE' = pP'

Ok?
--
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