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Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)

From Tycho Andersen <tycho@docker.com>
Newsgroups linux.kernel
Subject Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO)
Date 2017-09-21 03:10 +0200
Message-ID <urYa5-2kx-3@gated-at.bofh.it> (permalink)
References <un8Wu-3e6-13@gated-at.bofh.it> <un8Wt-3e6-11@gated-at.bofh.it> <urXxo-1QS-15@gated-at.bofh.it>
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On Wed, Sep 20, 2017 at 05:28:11PM -0700, Dave Hansen wrote:
> At a high level, does this approach keep an attacker from being able to
> determine the address of data in the linear map, or does it keep them
> from being able to *exploit* it?

It keeps them from exploiting it, by faulting when a physmap alias is
used.

> Can you have a ret2dir attack if the attacker doesn't know the
> address, for instance?

Yes, through a technique similar to heap spraying. The original paper
has a study of this, section 5.2 outlines the attack and 7.2 describes
their success rate:

http://www.cs.columbia.edu/~vpk/papers/ret2dir.sec14.pdf

Tycho

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Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame  Ownership (XPFO) Dave Hansen <dave.hansen@intel.com> - 2017-09-21 02:30 +0200
  Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame  Ownership (XPFO) Tycho Andersen <tycho@docker.com> - 2017-09-21 03:10 +0200

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