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From: Lokesh Gidra <lokeshgidra@google.com>
To: James Morris <jmorris@namei.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Eric Biggers <ebiggers@kernel.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Paul Moore <paul@paul-moore.com>,
	Eric Paris <eparis@parisplace.org>,
	Daniel Colascione <dancol@dancol.org>,
	Kees Cook <keescook@chromium.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	KP Singh <kpsingh@google.com>,
	David Howells <dhowells@redhat.com>,
	Thomas Cedeno <thomascedeno@google.com>,
	Anders Roxell <anders.roxell@linaro.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	Matthew Garrett <matthewgarrett@google.com>,
	Aaron Goidel <acgoide@tycho.nsa.gov>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>,
	YueHaibing <yuehaibing@huawei.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Alexey Budankov <alexey.budankov@linux.intel.com>,
	Adrian Reber <areber@redhat.com>,
	Aleksa Sarai <cyphar@cyphar.com>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	SElinux list <selinux@vger.kernel.org>,
	Kalesh Singh <kaleshsingh@google.com>,
	Calin Juravle <calin@google.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Nick Kralevich <nnk@google.com>,
	Jeffrey Vander Stoep <jeffv@google.com>,
	kernel-team@android.com
Subject: Re: [PATCH v6 0/3] SELinux support for anonymous inodes and UFFD
Date: Thu, 20 Aug 2020 20:48:52 -0700	[thread overview]
Message-ID: <CA+EESO5u89hEqgmBZMKq9njHvAKyWJJusVtkSLFHoQpv8rBzMg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LRH.2.21.2008210433591.29407@namei.org>

On Thu, Aug 20, 2020 at 11:36 AM James Morris <jmorris@namei.org> wrote:
>
> On Fri, 7 Aug 2020, Lokesh Gidra 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 in the future, other kinds of
> > anonymous-inode-based file descriptor.  SELinux policy authors can
> > apply policy types to anonymous inodes by providing name-based
> > transition rules keyed off the anonymous inode internal name (
> > "[userfaultfd]" in the case of userfaultfd(2) file descriptors) and
> > applying policy to the new SIDs thus produced.
>
> Can you expand more on why this would be useful, e.g. use-cases?
>
With SELinux managed userfaultfd file descriptors, an administrator
can control creation and movement of them. In particular, handling of
a userfaultfd descriptor by a different process is essentially a
ptrace access into the process, without any of the
corresponding security_ptrace_access_check() checks. For privacy, the
admin may want to deny such accesses,
which is possible with SELinux support.

I'll add this use case in the cover letter too in the next version.

      reply	other threads:[~2020-08-21  3:49 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-07 22:49 Lokesh Gidra
2020-08-07 22:49 ` [PATCH v6 1/3] Add a new LSM-supporting anonymous inode interface Lokesh Gidra
2020-08-07 23:02   ` Al Viro
2020-08-17 21:10     ` Lokesh Gidra
2020-08-07 22:49 ` [PATCH v6 2/3] Teach SELinux about anonymous inodes Lokesh Gidra
2020-08-07 22:49 ` [PATCH v6 3/3] Wire UFFD up to SELinux Lokesh Gidra
2020-08-20 18:35 ` [PATCH v6 0/3] SELinux support for anonymous inodes and UFFD James Morris
2020-08-21  3:48   ` Lokesh Gidra [this message]

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