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

[David Brown]

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