From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jiri Kosina <jikos@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrea Arcangeli <aarcange@redhat.com>,
"Woodhouse, David" <dwmw@amazon.co.uk>,
Andi Kleen <ak@linux.intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
"Schaufler, Casey" <casey.schaufler@intel.com>,
linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v4 1/2] x86/speculation: apply IBPB more strictly to avoid cross-process data leak
Date: Fri, 7 Sep 2018 08:39:08 -0500 [thread overview]
Message-ID: <20180907133908.dbcqz3mnaneluvtk@treble> (raw)
In-Reply-To: <alpine.LRH.2.00.1809061029030.3446@gjva.wvxbf.pm>
On Thu, Sep 06, 2018 at 10:32:38AM +0200, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@suse.cz>
>
> Currently, we are issuing IBPB only in cases when switching into a non-dumpable
> process, the rationale being to protect such 'important and security sensitive'
> processess (such as GPG) from data leak into a different userspace process via
> spectre v2.
>
> This is however completely insufficient to provide proper userspace-to-userpace
> spectrev2 protection, as any process can poison branch buffers before being
> scheduled out, and the newly scheduled process immediately becomes spectrev2
"becomes a"
> victim.
>
> In order to minimize the performance impact (for usecases that do require
> spectrev2 protection), issue the barrier only in cases when switching between
> processess where the victim can't be ptraced by the potential attacker (as in
"processes"
> such cases, the attacker doesn't have to bother with branch buffers at all).
>
> Fixes: 18bf3c3ea8 ("x86/speculation: Use Indirect Branch Prediction Barrier in context switch")
> Originally-by: Tim Chen <tim.c.chen@linux.intel.com>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
--
Josh
next prev parent reply other threads:[~2018-09-07 13:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 8:17 [PATCH v4 0/2] Harden spectrev2 userspace-userspace protection Jiri Kosina
2018-09-06 8:32 ` [PATCH v4 1/2] x86/speculation: apply IBPB more strictly to avoid cross-process data leak Jiri Kosina
2018-09-07 13:39 ` Josh Poimboeuf [this message]
2018-09-06 8:33 ` [PATCH v4 2/2] x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation Jiri Kosina
2018-09-07 15:16 ` Josh Poimboeuf
2018-09-07 21:08 ` Thomas Gleixner
2018-09-07 21:27 ` Jiri Kosina
2018-09-08 6:45 ` Thomas Gleixner
2018-09-08 7:50 ` Jiri Kosina
2018-09-08 9:05 ` Thomas Gleixner
2018-09-06 8:18 [PATCH v4 1/2] x86/speculation: apply IBPB more strictly to avoid cross-process data leak Jiri Kosina
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