linux-kernel - Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can be applied on arbitrary tasks

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Message-ID: <nycvar.YFH.7.76.1809052029160.15880@cbobk.fhfr.pm>
Date:   Wed, 5 Sep 2018 20:35:19 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Andi Kleen <ak@...ux.intel.com>
cc:     Tim Chen <tim.c.chen@...ux.intel.com>,
        "Schaufler, Casey" <casey.schaufler@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        Oleg Nesterov <oleg@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can
 be applied on arbitrary tasks

On Wed, 5 Sep 2018, Andi Kleen wrote:

> Please if you repost include plenty of performance numbers for multi 
> threaded workloads.  It's ridiculous to even discuss this without them.

Talking about ridiculous ... I find it a bit sad that Intel has let this 
be unfixed for 3/4 years in linux; that doesn't really signal deep 
dedication to customer safety. Have any STIBP patches been even submitted?

This is not the same situation as IBRS which was mostly ignored -- there 
we have retpolines to protect the kernel, and it's debatable whether it's 
exploitable on SKL at all.

Ignoring IBPB and STIBP is keeping the system plain vulnerable to 
user-user attacks, and us not providing users with possibiliy to easily 
mitigate, is a bit embarassing in my eyes.

Thanks,

-- 
Jiri Kosina
SUSE Labs