linux-kernel - Re: [PATCH 3/7] Add a UFFD_SECURE flag to the userfaultfd API.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALCETrVZHd+csdRL-uKbVN3Z7yeNNtxiDy-UsutMi=K3ZgCiYw@mail.gmail.com>
Date:   Sat, 12 Oct 2019 16:10:16 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Daniel Colascione <dancol@...gle.com>
Cc:     Linux API <linux-api@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, lokeshgidra@...gle.com,
        Nick Kralevich <nnk@...gle.com>, nosh@...gle.com,
        Tim Murray <timmurray@...gle.com>
Subject: Re: [PATCH 3/7] Add a UFFD_SECURE flag to the userfaultfd API.

On Sat, Oct 12, 2019 at 12:16 PM Daniel Colascione <dancol@...gle.com> wrote:
>
> The new secure flag makes userfaultfd use a new "secure" anonymous
> file object instead of the default one, letting security modules
> supervise userfaultfd use.
>
> Requiring that users pass a new flag lets us avoid changing the
> semantics for existing callers.

Is there any good reason not to make this be the default?

The only downside I can see is that it would increase the memory usage
of userfaultfd(), but that doesn't seem like such a big deal.  A
lighter-weight alternative would be to have a single inode shared by
all userfaultfd instances, which would require a somewhat different
internal anon_inode API.

In any event, I don't think that "make me visible to SELinux" should
be a choice that user code makes.

--Andy