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
