On Sun, Jul 16, 2017 at 05:42:25PM +0100, Ard Biesheuvel wrote: > On 16 July 2017 at 03:13, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > On Sat, Jul 15, 2017 at 5:42 AM, Ard Biesheuvel > > <ard.biesheuvel@xxxxxxxxxx> wrote: > >> (+ Mark, Will, Catalin) > >> > >> On 15 July 2017 at 01:38, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > >>> Document then /chosen/kaslr-seed property (and its interaction with the > >>> EFI_RNG_PROTOCOL API). > >>> > >>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > >>> --- > >>> Documentation/devicetree/bindings/chosen.txt | 22 ++++++++++++++++++++-- > >>> 1 file changed, 20 insertions(+), 2 deletions(-) > >> > >> For the textual changes: > >> > >> Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > >> > >> *However*, documenting the /chosen/kaslr-seed property promotes it > >> from a stub<->kernel private interface to an external ABI between the > >> kernel and the bootloader, and we need to reach agreement on whether > >> doing so is desirable first IMHO. > > > > Oh! I thought that was the point (having a bootloader provide kaslr > > entropy). And that in the EFI case, it was the stub doing it. > > It was the opposite, actually, The /chosen node is the most > appropriate way for the EFI stub to communicate a seed value to the > kernel proper, given how it is needed extremely early in the boot. > (Using UEFI config tables like we do for the /dev/random seed is not > possible for this) > > So as a side effect, other bootloaders can use the same mechanism. I'm > fine with that, but it needs to be an explicit decision by the > maintainers imo. I was under the impression that we'd already assumed other bootloaders could set this, so I don't have a problem promoting this to a defined public interface. I guess we just need Will and Catalin to agree. FWIW: Acked-by: Mark Rutland <mark.rutland@xxxxxxx> As an aside, we might want to make a split between /chosen properties which are Linux-specific (e.g. this), and those which are somewhat generic (e.g. stdout-path), since other OSs may/should respect those generic ones. Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
