Date: Sun, 7 Jan 2018 18:44:51 +0100
From: Willy Tarreau <w@1wt.eu>
To: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jon Masters <jcm@redhat.com>,
        "Woodhouse, David" <dwmw@amazon.co.uk>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <andi@firstfloor.org>,
        Greg Kroah-Hartman <gregkh@linux-foundation.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jeff Law <law@redhat.com>, Nick Clifton <nickc@redhat.com>
Subject: Re: Avoid speculative indirect calls in kernel
Message-ID: <20180107174451.GD9772@1wt.eu>
References: <20180104015920.1ad7b9d3@alans-desktop>
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 <403e65be-cfd1-fd08-0401-2e26470b63d4@redhat.com>
 <4dde456c-fd15-e768-8876-5844c8b7c455@redhat.com>
 <alpine.DEB.2.20.1801050153290.2127@nanos>
 <20180105064946.GA4007@1wt.eu>
 <44f1b753-47d3-82e3-9401-256b4beadd4f@intel.com>
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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