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

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Message-ID: <20180107174451.GD9772@1wt.eu>
Date:   Sun, 7 Jan 2018 18:44:51 +0100
From:   Willy Tarreau <w@....eu>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        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, Jan 07, 2018 at 03:14:10PM +0100, Borislav Petkov wrote:
> On Fri, Jan 05, 2018 at 08:13:33AM +0100, Willy Tarreau wrote:
> > I'm not fond of running the mitigations, but given that a few sysops can
> > connect to the machine to collect stats or counters, I think it would be
> > better to ensure these people can't happily play with the exploits to
> > dump stuff they shouldn't have access to.
> 
> So if someone exploits the "trusted" process, and then dumps all memory,
> you have practically lost.

Exactly, but there's much more to gain by owning this process anyway in
certain cases than just dumping a few hundreds of kernel bytes.

That's where I consider that "trusted" is more "critical" than "safe" :
if it dies, we all die anyway. Just like you have to trust your plane's
pilot eventhough you don't know him personally.

Willy