On Fri, Dec 20, 2013 at 03:20:16PM -0800, Kees Cook wrote: > On Fri, Dec 20, 2013 at 3:11 PM, Eric W. Biederman > <ebied...@xmission.com> wrote: > > Vivek Goyal <vgo...@redhat.com> writes: > > > >> On Thu, Dec 19, 2013 at 01:54:39PM +0100, Torsten Duwe wrote: > >>> On Tue, Nov 26, 2013 at 09:27:59AM -0500, Vivek Goyal wrote: > > > >>> IMO it's up to user land to search lists of certificates, and present > >>> only the final chain of trust to the kernel for checking. > >>> > >>> ELF is the preferred format for most sane OSes and firmware, and a > >>> detached > >>> signature would probably be simplest to check. If we have the choice, > >>> without restrictions from braindead boot loaders, ELF should be first. > >>> And if the pesigning isn't usable and another sig is needed anyway, > >>> why not apply that to vmlinux(.gz) ? > >> > >> I have yet to look deeper into it that if we can sign elf images and > >> just use elf loader. And can use space extract the elf image out of > >> a bzImage and pass it to kernel. > >> > >> Even if it is doable, one disadvantage seemed to be that extracted > >> elf images will have to be written to a file so thta it's file descriptor > >> can be passed to kernel. And that assumed writable root and we chrome > >> folks seems to have setups where root is not writable. > > > > In that case the chrome folks would simply have to use an ELF format > > kernel and not a bzImage. > > If we're doing fd origin verification (not signatures), can't we > continue to use a regular bzImage?
If secureboot is enabled, it enforces module signature verification. I think similar will happen for kexec too. How would kernel know that on a secureboot platform fd original verification will happen and it is sufficient. I personally want to support bzImage as well (apart from ELF) because distributions has been shipping bzImage for a long time and I don't want to enforce a change there because of secureboot. It is not necessary. Right now I am thinking more about storing detached bzImage signatures and passing those signatures to kexec system call. Thanks Vivek -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
