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From:   Florian Weimer <fweimer@redhat.com>
To:     Steve Grubb <sgrubb@redhat.com>
Cc:     Jan Kara <jack@suse.cz>,
        =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= <mic@digikod.net>,
        linux-kernel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
        James Morris <jmorris@namei.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Kees Cook <keescook@chromium.org>,
        Matthew Garrett <mjg59@google.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= <mickael.salaun@ssi.gouv.fr>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Philippe =?utf-8?Q?Tr=C3=A9buchet?= 
        <philippe.trebuchet@ssi.gouv.fr>, Shuah Khan <shuah@kernel.org>,
        Thibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>,
        Vincent Strubel <vincent.strubel@ssi.gouv.fr>,
        Yves-Alexis Perez <yves-alexis.perez@ssi.gouv.fr>,
        kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-fsdevel@vger.kernel.org,
        Matthew Bobrowski <mbobrowski@mbobrowski.org>
Subject: Re: [RFC PATCH v1 1/5] fs: Add support for an O_MAYEXEC flag on sys_open()
References: <20181212081712.32347-1-mic@digikod.net>
        <20181212081712.32347-2-mic@digikod.net>
        <20181212144306.GA19945@quack2.suse.cz> <3452959.b6JmBh7Lnt@x2>
Date:   Tue, 16 Apr 2019 13:49:39 +0200
In-Reply-To: <3452959.b6JmBh7Lnt@x2> (Steve Grubb's message of "Mon, 15 Apr
        2019 14:47:49 -0400")
Message-ID: <87wojuxj8s.fsf@oldenburg2.str.redhat.com>
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* 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