[patch] exec-shield patch for 2.6.7-rc2-bk2, integrated with NX
From: Ingo Molnar
Date: Wed Jun 02 2004 - 16:07:55 EST
Here's the latest exec-shield patch for 2.6.7-rc2-bk2, integrated with
the 'NX' feature (see the announcement from earlier today):
http://redhat.com/~mingo/exec-shield/exec-shield-on-nx-2.6.7-rc2-bk2-A7
you first have to apply the NX patch, which can be found at:
http://redhat.com/~mingo/nx-patches/nx-2.6.7-rc2-bk2-AE
prebuild kernel RPMs for Fedora Core 2, with this latest version of
exec-shield, are available at:
http://redhat.com/~arjanv/2.6/RPMS.kernel/
(kernel-2.6.6-1.411 has this latest, NX-aware exec-shield.)
if the CPU supports NX (and the kernel has been compiled with
CONFIG_HIGHMEM64G) then exec-shield will use NX to provide page-level
finegrained control over execution. On legacy CPUs that dont support NX
the segment-limit method is used to control execution (in a coarser
way). In the NX case the segment-limit is turned off altogether.
e.g. on an Athlon64 box the boot message looks:
NX (Execute Disable) protection: active
on a CPU without NX the boot message is:
NX (Execute Disable) protection: not present!
Using x86 segment limits to approximate NX protection
note: the NX patch will also protect against kernel-space code
injection.
all the other components of exec-shield are identical between NX and
non-NX: the brk area is non-executable, libraries and PIE binaries are
moved into the ascii-shield as much as possible, and all aspects of the
address space are randomized.
Ingo
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