linux-kernel - Re: [kernel-hardening] [RFC, PATCH] x86_64: KAISER

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <62c69fb5-03a8-4f30-cbc1-4955e9efbb18@iaik.tugraz.at>
Date:   Mon, 8 May 2017 15:53:20 +0200
From:   Daniel Gruss <daniel.gruss@...k.tugraz.at>
To:     David Gens <david.gens@...tu-darmstadt.de>,
        Thomas Garnier <thgarnie@...gle.com>
CC:     kernel list <linux-kernel@...r.kernel.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        <clementine.maurice@...k.tugraz.at>, <moritz.lipp@...k.tugraz.at>,
        Michael Schwarz <michael.schwarz@...k.tugraz.at>,
        Richard Fellner <richard.fellner@...dent.tugraz.at>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>, <anders.fogh@...ta-adan.de>
Subject: Re: [kernel-hardening] [RFC, PATCH] x86_64: KAISER - do not map
 kernel in user mode

On 06.05.2017 10:38, Daniel Gruss wrote:
> On 2017-05-06 06:02, David Gens wrote:
>> Assuming that their patch indeed leaks per-cpu addresses.. it might not
>> necessarily
>> be required to change it.
>
> I think we're not leaking them (unless we still have some bug in our code).

Just to correct my answer here as well: Although we experimented with fixed mappings for per-cpu addresses, the current 
patch does not incorporate this yet, so it indeed still leaks. However, it is not a severe problem. The mapping of the 
required (per-cpu) variables would be at a fixed location in the user CR3, instead of the ones that are used in the kernel.