From: Andrea Arcangeli <aarcange@redhat.com>
To: Lokesh Gidra <lokeshgidra@google.com>
Cc: Kees Cook <keescook@chromium.org>,
Jonathan Corbet <corbet@lwn.net>, Peter Xu <peterx@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Stephen Smalley <stephen.smalley.work@gmail.com>,
Eric Biggers <ebiggers@kernel.org>,
Daniel Colascione <dancol@dancol.org>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, kaleshsingh@google.com,
calin@google.com, surenb@google.com, nnk@google.com,
jeffv@google.com, kernel-team@android.com,
Mike Rapoport <rppt@linux.vnet.ibm.com>, Shaohua Li <shli@fb.com>,
Jerome Glisse <jglisse@redhat.com>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Mel Gorman <mgorman@techsingularity.net>,
Nitin Gupta <nigupta@nvidia.com>,
Vlastimil Babka <vbabka@suse.cz>,
Iurii Zaikin <yzaikin@google.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Daniel Colascione <dancol@google.com>
Subject: Re: [PATCH v5 1/2] Add UFFD_USER_MODE_ONLY
Date: Fri, 23 Oct 2020 22:08:43 -0400 [thread overview]
Message-ID: <20201024020843.GB19707@redhat.com> (raw)
In-Reply-To: <20201011062456.4065576-2-lokeshgidra@google.com>
On Sat, Oct 10, 2020 at 11:24:55PM -0700, Lokesh Gidra wrote:
> userfaultfd handles page faults from both user and kernel code.
> Add a new UFFD_USER_MODE_ONLY flag for userfaultfd(2) that makes
> the resulting userfaultfd object refuse to handle faults from kernel
> mode, treating these faults as if SIGBUS were always raised, causing
> the kernel code to fail with EFAULT.
>
> A future patch adds a knob allowing administrators to give some
> processes the ability to create userfaultfd file objects only if they
> pass UFFD_USER_MODE_ONLY, reducing the likelihood that these processes
> will exploit userfaultfd's ability to delay kernel page faults to open
> timing windows for future exploits.
>
> Signed-off-by: Daniel Colascione <dancol@google.com>
> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
next prev parent reply other threads:[~2020-10-24 2:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-11 6:24 [PATCH v5 0/2] Control over userfaultfd kernel-fault handling Lokesh Gidra
2020-10-11 6:24 ` [PATCH v5 1/2] Add UFFD_USER_MODE_ONLY Lokesh Gidra
2020-10-24 2:08 ` Andrea Arcangeli [this message]
2020-10-11 6:24 ` [PATCH v5 2/2] Add user-mode only option to unprivileged_userfaultfd sysctl knob Lokesh Gidra
2020-10-24 2:48 ` Andrea Arcangeli
2020-10-24 4:08 ` Lokesh Gidra
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