Re: [kernel-hardening] Self Introduction

[David Brown <david.brown@linaro.org>]

On Wed, Dec 09, 2015 at 04:14:20PM -0800, Kees Cook wrote:

>Great! It might be valuable to read through this mailing lists's
>threads over the last month. We discuss a few of the features and some
>work has been started.

Reading through stuff now.  Looks like the list got quite a boost in
November.

>> I suspect part of the challenge is going to be clearly describing the
>> various features along with specific examples of already-discovered
>> exploits that the feature would have mitigated.
>
>Yes indeed. :) That's why I've arranged the wiki the way I did:
>classes and methods first, with potential solutions listed under them.
>We want to start with problem descriptions and work from actual
>exploits when possible.
>
>This is why the recent x86 VDSO attack was very timely: it
>demonstrates cleanly why we want __ro_after_init (née __read_only) in
>upstream. (As well as the constification plugin.)

Which also seems like this will be quite useful on ARM as well.  Do
you know any efforts to do this?

>> Most recently, I backported ARM PAN support to the Linaro stable
>> kernels (3.18 and 4.1).
>
>Excellent! Yes, I did a port to Brillo's v4.1 tree as well. It's very
>nice to have a UDEREF-like feature on arm. It's too bad this doesn't
>exist for Intel yet, but I'm hoping they'll step up.
>
>For 3.18, is this the right place to be looking?
>https://git.linaro.org/gitweb?p=kernel/linux-linaro-stable.git;a=shortlog;h=refs/heads/linux-linaro-lsk-v3.18

It will be once it gets through testing.
https://git.linaro.org/kernel/linux-linaro-stable.git/shortlog/refs/heads/v3.18/topic/PAN
to peek before then.  There's also
https://git.linaro.org/kernel/linux-linaro-stable.git/shortlog/refs/heads/v4.1/topic/PAN
for the 4.1 tree.

Should I CC kernel-hardening when sending patches for the Linaro
stable kernels?

>I'd love to see CONFIG_CPU_SW_DOMAIN_PAN into the AOSP 3.18 android kernel too.

I'll put this on my list to investigate.  Sadly, it looks like there
is a bit of a window of ARM CPUs where neither solution will work;
Basically the pre V8.1 64-bit.

In fact, I don't have any hardware yet that supports PAN.  I've done
all of the testing in emulation.

David