From: Pavel Machek <pavel@ucw.cz>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>,
tglx@linuxtronix.de,
Greg Kroah-Hartman <gregkh@linux-foundation.org>,
dwmw@amazon.co.uk, Tim Chen <tim.c.chen@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Dave Hansen <dave.hansen@intel.com>
Subject: Re: Avoid speculative indirect calls in kernel
Date: Thu, 4 Jan 2018 12:26:14 +0100 [thread overview]
Message-ID: <20180104112614.GA1702@amd> (raw)
In-Reply-To: <CA+55aFzCocoK+4kxAUEhaxxba4RTv3ewBmhiZ8Osc9iDkBtCEQ@mail.gmail.com>
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On Wed 2018-01-03 15:51:35, Linus Torvalds wrote:
> On Wed, Jan 3, 2018 at 3:09 PM, Andi Kleen <andi@firstfloor.org> wrote:
> > This is a fix for Variant 2 in
> > https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html
> >
> > Any speculative indirect calls in the kernel can be tricked
> > to execute any kernel code, which may allow side channel
> > attacks that can leak arbitrary kernel data.
>
> Why is this all done without any configuration options?
>
> A *competent* CPU engineer would fix this by making sure speculation
> doesn't happen across protection domains. Maybe even a L1 I$ that is
> keyed by CPL.
Would that be enough?
AFAICT this will be pretty tricky to fix; it looks like you could
"attack" one userland application from another. Probing does not have
to work on L1 cache level; even main memory has "state".
It seems that complete fix would be considering any cache modification
and any memory access as a "side effect" -- so not okay to do
speculatively.
But that sounds... quite expensive for the performance...?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-01-04 11:26 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-03 23:09 Avoid speculative indirect calls in kernel Andi Kleen
2018-01-03 23:09 ` [PATCH 01/11] x86/retpoline: Define retpoline indirect thunk and macros Andi Kleen
2018-01-03 23:09 ` [PATCH 02/11] x86/retpoline/crypto: Convert crypto assembler indirect jumps Andi Kleen
2018-01-03 23:09 ` [PATCH 03/11] x86/retpoline/entry: Convert entry " Andi Kleen
2018-01-03 23:09 ` [PATCH 04/11] x86/retpoline/ftrace: Convert ftrace " Andi Kleen
2018-01-03 23:09 ` [PATCH 05/11] x86/retpoline/hyperv: Convert " Andi Kleen
2018-01-03 23:09 ` [PATCH 06/11] x86/retpoline/crypto: Convert xen " Andi Kleen
2018-01-03 23:09 ` [PATCH 07/11] x86/retpoline/checksum32: Convert " Andi Kleen
2018-01-03 23:09 ` [PATCH 08/11] x86/retpoline/irq32: " Andi Kleen
2018-01-03 23:09 ` [PATCH 09/11] x86/retpoline: Finally enable retpoline for C code Andi Kleen
2018-01-04 8:28 ` Greg KH
2018-01-04 8:30 ` Dave Hansen
2018-01-03 23:09 ` [PATCH 10/11] retpoline/taint: Taint kernel for missing retpoline in compiler Andi Kleen
2018-01-04 0:29 ` Thomas Gleixner
2018-01-04 0:35 ` Randy Dunlap
2018-01-03 23:09 ` [PATCH 11/11] retpoline/objtool: Disable some objtool warnings Andi Kleen
2018-01-03 23:51 ` Avoid speculative indirect calls in kernel Linus Torvalds
2018-01-04 0:00 ` Alan Cox
2018-01-04 0:09 ` Andi Kleen
2018-01-04 0:12 ` Thomas Gleixner
2018-01-04 0:15 ` Andi Kleen
2018-01-04 0:19 ` Jiri Kosina
2018-01-05 2:01 ` james harvey
2018-01-05 10:40 ` Woodhouse, David
2018-01-05 12:29 ` james harvey
2018-01-05 12:06 ` Alan Cox
2018-01-04 0:29 ` Alan Cox
2018-01-04 0:31 ` Thomas Gleixner
2018-01-04 0:38 ` Alan Cox
2018-01-04 0:40 ` Andi Kleen
2018-01-04 8:15 ` Woodhouse, David
2018-01-04 15:53 ` Andi Kleen
2018-01-04 15:55 ` Woodhouse, David
2018-01-04 0:20 ` Linus Torvalds
2018-01-04 0:26 ` Thomas Gleixner
2018-01-04 0:18 ` David Lang
2018-01-04 1:00 ` Paul Turner
2018-01-04 1:41 ` Paolo Bonzini
2018-01-04 1:59 ` Alan Cox
2018-01-04 2:11 ` Paolo Bonzini
2018-01-04 8:20 ` Woodhouse, David
2018-01-04 11:42 ` Pavel Machek
2018-01-04 11:47 ` Woodhouse, David
2018-01-04 14:20 ` Paolo Bonzini
2018-01-04 14:51 ` Andrew Cooper
2018-01-04 15:29 ` Woodhouse, David
2018-01-04 15:32 ` Paolo Bonzini
2018-01-04 15:37 ` Andrew Cooper
2018-01-04 16:15 ` David Woodhouse
2018-01-04 20:00 ` Tom Lendacky
2018-01-04 20:05 ` David Woodhouse
2018-01-04 23:47 ` Tom Lendacky
2018-01-05 0:06 ` Andrew Cooper
2018-01-05 0:26 ` Tom Lendacky
2018-01-04 16:52 ` Andrea Arcangeli
2018-01-04 15:32 ` Paolo Bonzini
2018-01-04 16:25 ` Andrea Arcangeli
2018-01-04 17:04 ` Alan Cox
2018-01-04 17:40 ` Andrea Arcangeli
2018-01-04 17:13 ` Dave Hansen
2018-01-04 17:15 ` Paolo Bonzini
2018-01-04 18:05 ` Andrea Arcangeli
2018-01-04 14:55 ` Woodhouse, David
2018-01-04 18:24 ` Pavel Machek
2018-01-04 19:57 ` Jon Masters
2018-01-05 0:41 ` Jon Masters
2018-01-05 0:54 ` Thomas Gleixner
2018-01-05 4:11 ` Jon Masters
2018-01-05 9:59 ` Thomas Gleixner
2018-01-08 10:28 ` Andrea Arcangeli
2018-01-08 20:42 ` [tip:x86/pti] x86/tboot: Unbreak tboot with PTI enabled tip-bot for Dave Hansen
2018-01-08 20:53 ` Avoid speculative indirect calls in kernel Thomas Gleixner
2018-01-08 21:32 ` Andrea Arcangeli
2018-01-10 0:45 ` Thomas Gleixner
2018-01-10 1:11 ` Dave Hansen
2018-01-10 16:02 ` Thomas Gleixner
2018-01-05 6:49 ` Willy Tarreau
2018-01-05 6:57 ` Dave Hansen
2018-01-05 7:13 ` Willy Tarreau
2018-01-07 14:14 ` Borislav Petkov
2018-01-07 17:21 ` David Lang
2018-01-07 18:49 ` Borislav Petkov
2018-01-07 17:44 ` Willy Tarreau
2018-01-07 18:55 ` Borislav Petkov
2018-01-07 22:10 ` Willy Tarreau
2018-01-08 9:18 ` Thomas Gleixner
2018-01-08 9:29 ` Willy Tarreau
2018-01-08 16:22 ` Borislav Petkov
2018-01-08 16:53 ` Willy Tarreau
2018-01-05 12:12 ` Alan Cox
2018-01-09 1:44 ` Samir Bellabes
[not found] ` <CAL9bgJ8XNJgCtxR6+M+Vm9eDBVZ4Dyi_-Lt-Q1ei9N=TE2c6cg@mail.gmail.com>
2018-01-07 5:04 ` Fwd: " Kiernan Hager
2018-01-07 6:39 ` Willy Tarreau
2018-01-07 14:01 ` Alan Cox
2018-01-07 17:47 ` Willy Tarreau
2018-01-07 18:01 ` Ivan Ivanov
2018-01-07 18:16 ` Woodhouse, David
2018-01-04 11:26 ` Pavel Machek [this message]
2018-01-04 11:54 ` Alan Cox
2018-01-04 18:33 ` Linus Torvalds
2018-01-04 20:08 ` Jon Masters
-- strict thread matches above, loose matches on Subject: below --
2018-01-04 2:00 Andi Kleen
2018-01-04 11:49 ` Pavel Machek
2018-01-04 12:09 ` Alan Cox
2018-01-04 13:32 ` Pavel Machek
2018-01-12 8:20 Dr. Greg Wettstein
2018-02-23 21:10 Ywe Cærlyn
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