Re: [kernel-hardening] Re: [PATCH v3 04/13] crypto/rng: ensure that the RNG is ready before using

[Mark Rutland <mark.rutland@arm.com>]

On Wed, Jun 07, 2017 at 01:00:25PM -0400, Daniel Micay wrote:
> > On the better bootloaders, an initramfs segment can be loaded
> > independently (and you can have as many as required), which makes an
> > early_initramfs a more palatable vector to inject large amounts of
> > entropy into the next boot than, say, modifying the kernel image
> > directly at every boot/shutdown to stash entropy in there somewhere.

[...]
 
> I didn't really understand the device tree approach and mentioned a
> few times before. Passing via the kernel cmdline is a lot simpler than
> modifying the device tree in-memory and persistent modification isn't
> an option unless verified boot is missing anyway.

I might be missing something here, but the command line is inside of the
device tree, at /chosen/bootargs, so modifying the kernel command line
*is* modifying the device tree in-memory.

For arm64, we have a /chosen/kaslr-seed property that we hope
FW/bootloaders fill in, and similar could be done for some initial
entropy, provided appropriate HW/FW support.

Thanks,
Mark.