Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree

H. Peter Anvin
2012-04-09T23:25:13Z

On 04/09/2012 03:24 PM, Cyrill Gorcunov wrote:
>>
>> Having re-read most of the (enormous) email discussion on the kcmp()
>> syscall patch, I'm thinking:
>>
>> - Nobody seems to understand the obfuscation logic. Jon sounded
>> confused, Oleg sounds confused and it's rather unclear what it does,
>> how it does it and why it does it.
>
> The obfuscation logic was done with great help from hpa@. And the main
> idea was to have ordered results after obfuscation. Per-type noise increase
> randomization of results. So Andrew, I actually dont know what to add
> here. We don't want to provide kernel order back to user-space in
> naked manner.
>

The obfuscation logic is to provide a 1:1 mapping but which doesn't
preserve ordering, thereby avoid leaking information of kernel pointers
to user space.

-hpa