Re: [kernel-hardening] [PATCH v4 0/8] introduce post-init read-only memory

[Laura Abbott]

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