linux-kernel - Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace page tables

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] [day] [month] [year] [list]

Message-ID: <20171123104752.GB17990@amd>
Date:   Thu, 23 Nov 2017 11:47:52 +0100
From:   Pavel Machek <pavel@....cz>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 00/23] KAISER: unmap most of the kernel from userspace
 page tables

On Wed 2017-11-22 17:19:07, Pavel Machek wrote:
> Hi!
> 
> > KAISER makes it harder to defeat KASLR, but makes syscalls and
> > interrupts slower.  These patches are based on work from a team at
> > Graz University of Technology posted here[1].  The major addition is
> > support for Intel PCIDs which builds on top of Andy Lutomorski's PCID
> > work merged for 4.14.  PCIDs make KAISER's overhead very reasonable
> > for a wide variety of use cases.
> 
> Is it useful?
> 
> > Full Description:
> > 
> > KAISER is a countermeasure against attacks on kernel address
> > information.  There are at least three existing, published,
> > approaches using the shared user/kernel mapping and hardware features
> > to defeat KASLR.  One approach referenced in the paper locates the
> > kernel by observing differences in page fault timing between
> > present-but-inaccessable kernel pages and non-present pages.
> 
> I mean... evil userspace will still be able to determine kernel's
> location using cache aliasing effects, right?

Issues with AnC attacks are tracked via several CVE identifiers.

CVE-2017-5925 is assigned to track the developments for Intel processors
CVE-2017-5926 is assigned to track the developments for AMD processors

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Download attachment "signature.asc" of type "application/pgp-signature" (182 bytes)