From: casey.schaufler@intel.com (Schaufler, Casey)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v5 5/5] sidechannel: Linux Security Module for sidechannel
Date: Fri, 28 Sep 2018 17:40:52 +0000 [thread overview]
Message-ID: <99FC4B6EFCEFD44486C35F4C281DC6732146466E@ORSMSX107.amr.corp.intel.com> (raw)
In-Reply-To: <alpine.LRH.2.21.1809290233130.15725@namei.org>
> -----Original Message-----
> From: James Morris [mailto:jmorris at namei.org]
> Sent: Friday, September 28, 2018 9:33 AM
> To: Jann Horn <jannh@google.com>
> Cc: Schaufler, Casey <casey.schaufler@intel.com>; Casey Schaufler
> <casey@schaufler-ca.com>; kristen at linux.intel.com; Kernel Hardening
> <kernel-hardening@lists.openwall.com>; Dock, Deneen T
> <deneen.t.dock@intel.com>; kernel list <linux-kernel@vger.kernel.org>;
> Hansen, Dave <dave.hansen@intel.com>; linux-security-module <linux-security-
> module at vger.kernel.org>; selinux at tycho.nsa.gov; Arjan van de Ven
> <arjan@linux.intel.com>
> Subject: Re: [PATCH v5 5/5] sidechannel: Linux Security Module for sidechannel
>
> On Fri, 28 Sep 2018, Jann Horn wrote:
>
> > > so with this hard-coded logic, you are saying this case is
> > > 'safe' in a sidechannel context.
> > >
> > > Which hints at the deeper issue that containers are a userland
> > > abstraction. Protection of containers needs to be defined by userland
> > > policy.
> >
> > Or just compare mount namespaces additionally/instead. I think that
> > containers will always use those, because AFAIK nobody uses chroot()
> > for containers, given that the kernel makes absolutely no security
> > guarantees about chroot().
>
> We can't define this in the kernel. It has no concept of containers.
>
> People utilize some combination of namespaces and cgroups and call them
> containers,
There is an amazing variety of things called containers out there.
I cite them as a use case, not a requirement.
> but we can't make assumptions from the kernel on what any of
> this means from a security point of view, and hard-code kernel policy
> based on those assumptions.
We can assume that namespaces are being used as a separation mechanism.
That makes processes in different namespaces potentially vulnerable to
side-channel attacks. That's true regardless of whether or not someone is
using namespaces to implement containers.
> This is violating the principal of separating mechanism and policy, and
> also imposing semantics across the kernel/user boundary. The latter
> creates an ABI which we can then never break.
The effects of the sidechannel security module are not API visible.
The potential impact is on performance. This implementation of
PTRACE_MODE_SCHED does not change what happens, but may affect
when it happens. It is intended to aid in optimizing the use of expensive
anti-side-channel countermeasures.
prev parent reply other threads:[~2018-09-28 17:40 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-26 20:34 [PATCH v5 0/5] LSM: Support ptrace sidechannel access checks Casey Schaufler
2018-09-26 20:34 ` [PATCH v5 1/5] AppArmor: Prepare for PTRACE_MODE_SCHED Casey Schaufler
2018-09-26 21:16 ` Jann Horn
2018-09-26 21:18 ` Jann Horn
2018-09-26 22:47 ` Schaufler, Casey
2018-09-26 20:34 ` [PATCH v5 2/5] Smack: " Casey Schaufler
2018-09-26 21:30 ` Jann Horn
2018-09-26 22:53 ` Schaufler, Casey
2018-09-26 22:58 ` Jann Horn
2018-10-04 7:47 ` Jiri Kosina
2018-10-04 11:36 ` Jann Horn
2018-10-16 11:44 ` Jiri Kosina
2018-09-26 20:34 ` [PATCH v5 3/5] SELinux: " Casey Schaufler
2018-09-27 15:50 ` Stephen Smalley
2018-09-27 16:23 ` Schaufler, Casey
2018-09-26 20:34 ` [PATCH v5 4/5] Capability: Complete PTRACE_MODE_SCHED Casey Schaufler
2018-09-26 21:26 ` Jann Horn
2018-09-26 22:24 ` Schaufler, Casey
2018-09-26 20:34 ` [PATCH v5 5/5] sidechannel: Linux Security Module for sidechannel Casey Schaufler
2018-09-27 21:45 ` James Morris
2018-09-27 22:39 ` Casey Schaufler
2018-09-27 22:47 ` James Morris
2018-09-27 23:19 ` Schaufler, Casey
2018-09-27 23:43 ` James Morris
2018-09-27 23:47 ` Jann Horn
2018-09-28 16:33 ` James Morris
2018-09-28 17:40 ` Schaufler, Casey [this message]
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