linux-kernel - Re: [RFC PATCH v1 1/5] fs: Add support for an O_MAYEXEC flag on sys

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Message-ID: <87wojuxj8s.fsf@oldenburg2.str.redhat.com>
Date:   Tue, 16 Apr 2019 13:49:39 +0200
From:   Florian Weimer <fweimer@...hat.com>
To:     Steve Grubb <sgrubb@...hat.com>
Cc:     Jan Kara <jack@...e.cz>,
        Mickaël Salaün <mic@...ikod.net>,
        linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        James Morris <jmorris@...ei.org>,
        Jonathan Corbet <corbet@....net>,
        Kees Cook <keescook@...omium.org>,
        Matthew Garrett <mjg59@...gle.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Mickaël Salaün <mickael.salaun@....gouv.fr>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Philippe Trébuchet 
        <philippe.trebuchet@....gouv.fr>, Shuah Khan <shuah@...nel.org>,
        Thibaut Sautereau <thibaut.sautereau@....gouv.fr>,
        Vincent Strubel <vincent.strubel@....gouv.fr>,
        Yves-Alexis Perez <yves-alexis.perez@....gouv.fr>,
        kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-fsdevel@...r.kernel.org,
        Matthew Bobrowski <mbobrowski@...browski.org>
Subject: Re: [RFC PATCH v1 1/5] fs: Add support for an O_MAYEXEC flag on sys_open()

* Steve Grubb:

> This flag that is being proposed means that you would have to patch all 
> interpreters to use it. If you are sure that upstreams will accept that, why 
> not just change the policy to interpreters shouldn't execute anything unless 
> the execute bit is set? That is simpler and doesn't need a kernel change. And 
> setting the execute bit is an auditable event.

I think we need something like O_MAYEXEC so that security policies can
be enforced and noexec mounts can be detected.  I don't think it's a
good idea to do this in userspace, especially the latter.

Thanks,
Florian