linux-kernel - Re: Avoid speculative indirect calls in kernel

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Date:   Mon, 8 Jan 2018 10:18:09 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Willy Tarreau <w@....eu>
cc:     Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...el.com>,
        Jon Masters <jcm@...hat.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andi Kleen <andi@...stfloor.org>,
        Greg Kroah-Hartman <gregkh@...ux-foundation.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jeff Law <law@...hat.com>, Nick Clifton <nickc@...hat.com>
Subject: Re: Avoid speculative indirect calls in kernel

On Sun, 7 Jan 2018, Willy Tarreau wrote:
> On Sun, Jan 07, 2018 at 07:55:11PM +0100, Borislav Petkov wrote:
> > > Just like you have to trust your plane's pilot eventhough you don't
> > > know him personally.
> > 
> > Funny you should make that analogy. Remember that germanwings pilot?
> > People trusted him too.
> > 
> > Now imagine if the plane had protection against insane pilots... some of
> > those people might still be alive, who knows...
> 
> Sure but despite this case many people continue to take the plane because
> it's their only option to cross half of the world in a reasonable time.
> 
> Boris, I'm *not* contesting the performance resulting from the fixes,
> and I would never have been able to produce them myself had I to, so
> I'm really glad we have them. I just want to be clear that the big drop
> some of us are facing is not an option *at all* for certain processes
> in certain environments and that we'll either continue to run with
> pti=off or with pti=on + a finer grained setting ASAP.

No argument about that. We've looked into per process PTI very early and
decided not to go that route because of the time pressure and the risk. I'm
glad that we managed to pull it off at all without breaking the world
completely. It's surely doable and we all know that it has to be done, just
not right now as we have to fast track at least the basic protections for
the other two attack vectors.

You can be sure, that all people involved hate it more than you do.

Thanks,

	tglx