From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1761928AbcINSoV (ORCPT <rfc822;w@1wt.eu>);
        Wed, 14 Sep 2016 14:44:21 -0400
Received: from mail-yw0-f170.google.com ([209.85.161.170]:36416 "EHLO
        mail-yw0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1757554AbcINSoQ (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Wed, 14 Sep 2016 14:44:16 -0400
MIME-Version: 1.0
In-Reply-To: <20160914072415.26021-12-mic@digikod.net>
References: <20160914072415.26021-1-mic@digikod.net> <20160914072415.26021-12-mic@digikod.net>
From: Andy Lutomirski <luto@amacapital.net>
Date: Wed, 14 Sep 2016 11:43:54 -0700
Message-ID: <CALCETrXm18nNDY-a+toBEcjKKh+zOCVG0=t3ufkpROOHdqfqJQ@mail.gmail.com>
Subject: Re: [RFC v3 11/22] seccomp,landlock: Handle Landlock hooks per
 process hierarchy
To: =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= <mic@digikod.net>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Alexei Starovoitov <ast@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Daniel Mack <daniel@zonque.org>, David Drysdale <drysdale@google.com>,
        "David S . Miller" <davem@davemloft.net>,
        Elena Reshetova <elena.reshetova@intel.com>,
        "Eric W . Biederman" <ebiederm@xmission.com>,
        James Morris <james.l.morris@oracle.com>,
        Kees Cook <keescook@chromium.org>, Paul Moore <pmoore@redhat.com>,
        Sargun Dhillon <sargun@sargun.me>,
        "Serge E . Hallyn" <serge@hallyn.com>, Tejun Heo <tj@kernel.org>,
        Will Drewry <wad@chromium.org>,
        "kernel-hardening@lists.openwall.com" 
        <kernel-hardening@lists.openwall.com>,
        Linux API <linux-api@vger.kernel.org>,
        LSM List <linux-security-module@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        "open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Transfer-Encoding: 8bit
X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id u8EIiQbZ032582

On Wed, Sep 14, 2016 at 12:24 AM, Mickaël Salaün <mic@digikod.net> wrote:
> A Landlock program will be triggered according to its subtype/origin
> bitfield. The LANDLOCK_FLAG_ORIGIN_SECCOMP value will trigger the
> Landlock program when a seccomp filter will return RET_LANDLOCK.
> Moreover, it is possible to return a 16-bit cookie which will be
> readable by the Landlock programs in its context.

Are you envisioning that the filters will return RET_LANDLOCK most of
the time or rarely?  If it's most of the time, then maybe this could
be simplified a bit by unconditionally calling the landlock filter and
letting the landlock filter access a struct seccomp_data if needed.


>
> Only seccomp filters loaded from the same thread and before a Landlock
> program can trigger it through LANDLOCK_FLAG_ORIGIN_SECCOMP. Multiple
> Landlock programs can be triggered by one or more seccomp filters. This
> way, each RET_LANDLOCK (with specific cookie) will trigger all the
> allowed Landlock programs once.

This interface seems somewhat awkward.  Should we not have a way to
atomicaly install a whole pile of landlock filters and associated
seccomp filter all at once?

--Andy