lkml.org 
[lkml]   [2017]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 24/30] x86, kaiser: disable native VSYSCALL
On Thu, Nov 9, 2017 at 4:57 PM, Dave Hansen <dave.hansen@linux.intel.com> wrote:
> On 11/09/2017 04:53 PM, Andy Lutomirski wrote:
>>> The KAISER code attempts to "poison" the user portion of the kernel page
>>> tables. It detects the entries pages that it wants that it wants to
>>> poison in two ways:
>>> * Looking for addresses >= PAGE_OFFSET
>>> * Looking for entries without _PAGE_USER set
>> What do you mean "poison"?
>
> I meant the _PAGE_NX magic that we do in here:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-kaiser.git/commit/?h=kaiser-414rc7-20171108&id=c4f7d0819170761f092fcf2327b85b082368e73a
>
> to ensure that userspace is unable to run on the kernel PGD.

Aha, I get it. Why not just drop the _PAGE_USER check? You could
instead warn if you see a _PAGE_USER page that doesn't have the
correct address for the vsyscall.

\
 
 \ /
  Last update: 2017-11-10 02:06    [W:0.099 / U:1.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site