On 1/22/16 9:19 AM, David Brown wrote:
On Tue, Jan 19, 2016 at 10:08:34AM -0800, Kees Cook wrote:
This introduces __ro_after_init as a way to mark such memory, and uses
it on the x86 vDSO to kill an extant kernel exploitation method. Also
adds a new kernel parameter to help debug future use and adds an lkdtm
test to check the results.
I've tested these patches on 32-bit ARM using the provoke-crashes
test. However, they do require CONFIG_ARM_KERNMEM_PERMS to be enabled
as well, which does incur additional memory usage.
Do we want to consider making CONFIG_ARM_KERNMEM_PERMS default y for
security reasons, and just document that memory-constrained systems
may want to turn it off?
I'll test the arm64 next.
David
Kees had previously pushed a patch to do so but it exposed a couple of
underlying issues, mostly with low power paths
(c.f. http://article.gmane.org/gmane.linux.ports.arm.kernel/471199,
http://article.gmane.org/gmane.linux.kernel.mm/143489)
Those will need to be all fixed up before this could be made default.
Thanks,
Laura
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