linux-kernel - Re: [PATCH v6 7/7] ima: add policy support for the new file open MAY

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Message-ID: <202007160957.CABE4CC@keescook>
Date:   Thu, 16 Jul 2020 12:12:47 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Mickaël Salaün <mic@...ikod.net>
Cc:     linux-kernel@...r.kernel.org, Aleksa Sarai <cyphar@...har.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Christian Heimes <christian@...hon.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Deven Bowers <deven.desai@...ux.microsoft.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Eric Chiang <ericchiang@...gle.com>,
        Florian Weimer <fweimer@...hat.com>,
        James Morris <jmorris@...ei.org>, Jan Kara <jack@...e.cz>,
        Jann Horn <jannh@...gle.com>, Jonathan Corbet <corbet@....net>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>,
        Matthew Garrett <mjg59@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Mickaël Salaün <mickael.salaun@....gouv.fr>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Philippe Trébuchet 
        <philippe.trebuchet@....gouv.fr>,
        Scott Shell <scottsh@...rosoft.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Shuah Khan <shuah@...nel.org>,
        Steve Dower <steve.dower@...hon.org>,
        Steve Grubb <sgrubb@...hat.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Thibaut Sautereau <thibaut.sautereau@....gouv.fr>,
        Vincent Strubel <vincent.strubel@....gouv.fr>,
        kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v6 7/7] ima: add policy support for the new file open
 MAY_OPENEXEC flag

On Thu, Jul 16, 2020 at 04:40:15PM +0200, Mickaël Salaün wrote:
> 
> On 15/07/2020 22:40, Kees Cook wrote:
> > On Tue, Jul 14, 2020 at 08:16:38PM +0200, Mickaël Salaün wrote:
> >> From: Mimi Zohar <zohar@...ux.ibm.com>
> >>
> >> The kernel has no way of differentiating between a file containing data
> >> or code being opened by an interpreter.  The proposed O_MAYEXEC
> >> openat2(2) flag bridges this gap by defining and enabling the
> >> MAY_OPENEXEC flag.
> >>
> >> This patch adds IMA policy support for the new MAY_OPENEXEC flag.
> >>
> >> Example:
> >> measure func=FILE_CHECK mask=^MAY_OPENEXEC
> >> appraise func=FILE_CHECK appraise_type=imasig mask=^MAY_OPENEXEC
> >>
> >> Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
> >> Reviewed-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
> >> Acked-by: Mickaël Salaün <mic@...ikod.net>
> > 
> > (Process nit: if you're sending this on behalf of another author, then
> > this should be Signed-off-by rather than Acked-by.)
> 
> I'm not a co-author of this patch.

Correct, but you are part of the delivery path to its entry to the
tree. If you were co-author, you would include "Co-developed-by" with
a Signed-off-by. (So my nit stands)

For excruciating details:

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

"The Signed-off-by: tag indicates that the signer was ... in the patch’s
delivery path."

"Co-developed-by: ... is a used to give attribution to co-authors ..."

-- 
Kees Cook