Re: [PATCH 5/6] Pmalloc: self-test

[Kees Cook]

On Tue, Feb 20, 2018 at 8:40 AM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> wrote:
>
> On 13/02/18 01:43, Kees Cook wrote:
>> On Mon, Feb 12, 2018 at 8:53 AM, Igor Stoppa <igor.stoppa@xxxxxxxxxx> wrote:
>
> [...]
>
>>> +obj-$(CONFIG_PROTECTABLE_MEMORY_SELFTEST) += pmalloc-selftest.o
>>
>> Nit: self-test modules are traditionally named "test_$thing.o"
>> (outside of the tools/ directory).
>
> ok
>
> [...]
>
>> I wonder if lkdtm should grow a test too, to validate the RO-ness of
>> the allocations at the right time in API usage?
>
> sorry for being dense ... are you proposing that I do something to
> lkdtm_rodata.c ? An example would probably help me understand.

It would likely live in lkdtm_perms.c (or maybe lkdtm_heap.c). Namely,
use the pmalloc API and then attempt to write to a read-only variable
in the pmalloc region (to prove that the permission adjustment
actually happened). Likely a good example is
lkdtm_WRITE_RO_AFTER_INIT().

-Kees

-- 
Kees Cook
Pixel Security