From: David Woodhouse <dwmw2@infradead.org>
To: Dominik Brodowski <linux@dominikbrodowski.net>,
mingo@kernel.org, hpa@zytor.com, tim.c.chen@linux.intel.com,
linux-kernel@vger.kernel.org, tglx@linutronix.de
Cc: jpoimboe@redhat.com, "Wieczorkiewicz, Pawel" <wipawel@amazon.de>
Subject: Re: [tip:x86/pti] x86/speculation: Use Indirect Branch Prediction Barrier in context switch
Date: Thu, 01 Feb 2018 08:31:53 +0000 [thread overview]
Message-ID: <1517473913.18619.281.camel@infradead.org> (raw)
In-Reply-To: <20180131070300.GA28206@light.dominikbrodowski.net>
[-- Attachment #1: Type: text/plain, Size: 1103 bytes --]
On Wed, 2018-01-31 at 08:03 +0100, Dominik Brodowski wrote:
> Whether a process needs protection by IBPB on context switches is a
> different question to whether a process should be allowed to be dumped,
> though the former may be a superset of the latter. Enable IBPB on all
> context switches to a different userspace process, until we have a clear
> mitigation strategy for userspace against Spectre-v2 designed and
> implemented.
>
> ...
> if (tsk && tsk->mm &&
> - tsk->mm->context.ctx_id != last_ctx_id &&
> - get_dumpable(tsk->mm) != SUID_DUMP_USER)
> + tsk->mm->context.ctx_id != last_ctx_id)
> indirect_branch_prediction_barrier();
I understand your argument and I sympathise.
But that's going to hurt a *lot*, and we don't even have a viable
proof-of-concept for a user←→user Spectre v2 attack, do we? It's only
theoretical?
Show a working PoC and it makes the argument somewhat more
convincing...
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5213 bytes --]
next prev parent reply other threads:[~2018-02-01 8:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 22:04 [PATCH] x86/speculation: Use Indirect Branch Prediction Barrier in context switch David Woodhouse
2018-01-30 17:48 ` Josh Poimboeuf
2018-01-30 21:23 ` Tim Chen
2018-01-30 22:00 ` Borislav Petkov
2018-01-30 22:21 ` Thomas Gleixner
2018-01-30 22:55 ` Borislav Petkov
2018-01-31 3:59 ` Josh Poimboeuf
2018-01-31 23:25 ` Tim Chen
2018-01-30 20:38 ` Borislav Petkov
2018-01-30 21:03 ` Tim Chen
2018-01-30 21:57 ` Borislav Petkov
2018-01-30 22:26 ` Tim Chen
2018-01-30 22:43 ` Borislav Petkov
2018-01-31 0:25 ` Tim Chen
2018-01-31 0:41 ` Borislav Petkov
2018-01-30 22:39 ` [tip:x86/pti] " tip-bot for Tim Chen
2018-01-31 7:03 ` Dominik Brodowski
2018-01-31 13:24 ` Josh Poimboeuf
2018-02-01 8:25 ` Christian Brauner
2018-02-01 8:31 ` David Woodhouse [this message]
2018-02-01 15:40 ` Josh Poimboeuf
2018-02-04 19:39 ` Dominik Brodowski
2018-02-05 14:18 ` David Woodhouse
2018-02-05 19:35 ` Tim Chen
2018-02-05 19:35 ` Tim Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1517473913.18619.281.camel@infradead.org \
--to=dwmw2@infradead.org \
--cc=hpa@zytor.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@dominikbrodowski.net \
--cc=mingo@kernel.org \
--cc=tglx@linutronix.de \
--cc=tim.c.chen@linux.intel.com \
--cc=wipawel@amazon.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.