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Date: Tue, 10 Nov 2015 09:25:41 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
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To: "Theodore Ts'o" <tytso@mit.edu>
cc: Andy Lutomirski <luto@amacapital.net>,
        Serge Hallyn <serge.hallyn@ubuntu.com>,
        Kees Cook <keescook@chromium.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
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        Austin S Hemmelgarn <ahferroin7@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [KERNEL] Re: [KERNEL] Re: [KERNEL] Re: Kernel 4.3 breaks security
 in systems  using capabilities
In-Reply-To: <20151110124043.GC3717@thunk.org>
Message-ID: <alpine.DEB.2.20.1511100924280.8420@east.gentwo.org>
References: <20151106155303.GB6160@thunk.org> <20151106175619.GA19491@ikki.ethgen.ch> <20151106181820.GB16749@mail.hallyn.com> <20151107110246.GA7230@ikki.ethgen.ch> <5640C999.5050807@gmail.com> <20151109172340.GF3714@ikki.ethgen.ch> <5640EDB4.70407@gmail.com>
 <20151109212937.GA17624@ikki.ethgen.ch> <CALCETrUE5FwqtCBMq8+K6owwTn0vhdHjO0TzoMKhN6_vaNSRhw@mail.gmail.com> <20151110115526.GA2958@ikki.ethgen.ch> <20151110124043.GC3717@thunk.org>
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On Tue, 10 Nov 2015, Theodore Ts'o wrote:

> If you want to create a patch, my recommendation would be to do one
> that turns off ambient capabilities as a CONFIG option, and hide it
> under CONFIG_EXPERT.  Or maybe adding a new securebit which disables
> ambient capabilities.  Whether or not that will be acceptable
> upstream, I don't know, mainly because I think a strong case can be

That is already available and was submitted with the patch.

commit 746bf6d64275be0c65b0631d8a72b16f1454cfa1
Author: Andy Lutomirski <luto@kernel.org>
Date:   Fri Sep 4 15:42:51 2015 -0700

    capabilities: add a securebit to disable PR_CAP_AMBIENT_RAISE

    Per Andrew Morgan's request, add a securebit to allow admins to disable
    PR_CAP_AMBIENT_RAISE.  This securebit will prevent processes from adding
    capabilities to their ambient set.

    For simplicity, this disables PR_CAP_AMBIENT_RAISE entirely rather than
    just disabling setting previously cleared bits.

    Signed-off-by: Andy Lutomirski <luto@kernel.org>
    Acked-by: Andrew G. Morgan <morgan@kernel.org>
    Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Serge Hallyn <serge.hallyn@canonical.com>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Cc: Aaron Jones <aaronmdjones@gmail.com>
    Cc: Ted Ts'o <tytso@mit.edu>
    Cc: Andrew G. Morgan <morgan@kernel.org>
    Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
    Cc: Austin S Hemmelgarn <ahferroin7@gmail.com>
    Cc: Markku Savela <msa@moth.iki.fi>
    Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Cc: Michael Kerrisk <mtk.manpages@gmail.com>
    Cc: James Morris <james.l.morris@oracle.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>