On 30/05/2019 04:34, Kees Cook wrote:

On Wed, May 29, 2019 at 08:03:30PM +0100, Kristina Martsenko wrote:

quoted

Set up keys to use pointer authentication within the kernel. The kernel
will be compiled with APIAKey instructions, the other keys are currently
unused. Each task is given its own APIAKey, which is initialized during
fork. The key is changed during context switch and on kernel entry from
EL0.

A function that changes the key cannot return, so compile such functions
without pointer auth (using __no_ptrauth which will be defined to a
compiler function attribute later).

Signed-off-by: Kristina Martsenko <redacted>

Just so I'm reading this right: the kernel is only using APIAKey?

Yes, that's right. The compiler options (in patch #7) will compile the
kernel with only APIAKey instructions, so the kernel will only use
APIAKey. We don't initialize or install the other 4 keys for the kernel
(only for userspace). Let me know if the commit message could be clearer
in some way.

Reviewed-by: Kees Cook <redacted>

Thanks for all the review!

Kristina

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