linux-kernel - Re: [PATCH v2 0/6] Harden userfaultfd

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Message-ID: <245a7c82-93f6-1e1d-9250-499e00972f10@tycho.nsa.gov>
Date:   Wed, 12 Feb 2020 11:09:07 -0500
From:   Stephen Smalley <sds@...ho.nsa.gov>
To:     Daniel Colascione <dancol@...gle.com>,
        Casey Schaufler <casey@...aufler-ca.com>
Cc:     Tim Murray <timmurray@...gle.com>, Nosh Minwalla <nosh@...gle.com>,
        Nick Kralevich <nnk@...gle.com>,
        Lokesh Gidra <lokeshgidra@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>, selinux@...r.kernel.org,
        LSM List <linux-security-module@...r.kernel.org>
Subject: Re: [PATCH v2 0/6] Harden userfaultfd

On 2/11/20 6:27 PM, Daniel Colascione wrote:
> On Tue, Feb 11, 2020 at 3:13 PM Casey Schaufler <casey@...aufler-ca.com> wrote:
>>
>> On 2/11/2020 2:55 PM, Daniel Colascione wrote:
>>> Userfaultfd in unprivileged contexts could be potentially very
>>> useful. We'd like to harden userfaultfd to make such unprivileged use
>>> less risky. This patch series allows SELinux to manage userfaultfd
>>> file descriptors and allows administrators to limit userfaultfd to
>>> servicing user-mode faults, increasing the difficulty of using
>>> userfaultfd in exploit chains invoking delaying kernel faults.
>>>
>>> A new anon_inodes interface allows callers to opt into SELinux
>>> management of anonymous file objects. In this mode, anon_inodes
>>> creates new ephemeral inodes for anonymous file objects instead of
>>> reusing a singleton dummy inode. A new LSM hook gives security modules
>>> an opportunity to configure and veto these ephemeral inodes.
>>>
>>> Existing anon_inodes users must opt into the new functionality.
>>>
>>> Daniel Colascione (6):
>>>    Add a new flags-accepting interface for anonymous inodes
>>>    Add a concept of a "secure" anonymous file
>>>    Teach SELinux about a new userfaultfd class
>>>    Wire UFFD up to SELinux
>>>    Let userfaultfd opt out of handling kernel-mode faults
>>>    Add a new sysctl for limiting userfaultfd to user mode faults
>>
>> This must be posted to the linux Security Module list
>> <linux-security-module@...r.kernel.org>
> 
> Added. I thought selinux@ was sufficient.

scripts/get_maintainer.pl can be helpful in identifying relevant lists 
and maintainers for each patch.  I don't use its output blindly as it 
tends to over-approximate but since your patches span the VFS, LSM 
framework, and selinux, you do need to include relevant 
maintainers/lists for each.