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SubjectRe: [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
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