Messages in this thread | | | Date | Fri, 8 Sep 2017 12:07:51 +0900 | From | AKASHI Takahiro <> | Subject | Re: [PATCH 14/14] arm64: kexec_file: add vmlinux format support |
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On Tue, Aug 29, 2017 at 11:01:12AM +0100, Mark Rutland wrote: > On Thu, Aug 24, 2017 at 06:30:50PM +0100, Mark Rutland wrote: > > On Thu, Aug 24, 2017 at 05:18:11PM +0900, AKASHI Takahiro wrote: > > > The first PT_LOAD segment, which is assumed to be "text" code, in vmlinux > > > will be loaded at the offset of TEXT_OFFSET from the begining of system > > > memory. The other PT_LOAD segments are placed relative to the first one. > > > > I really don't like assuming things about the vmlinux ELF file. > > > > > Regarding kernel verification, since there is no standard way to contain > > > a signature within elf binary, we follow PowerPC's (not yet upstreamed) > > > approach, that is, appending a signature right after the kernel binary > > > itself like module signing. > > > > I also *really* don't like this. It's a bizarre in-band mechanism, > > without explcit information. It's not a nice ABI. > > > > If we can load an Image, why do we need to be able to load a vmlinux? > > So IIUC, the whole point of this is to be able to kexec_file_load() a > vmlinux + signature bundle, for !CONFIG_EFI kernels. > > For that, I think that we actually need a new kexec_file_load${N} > syscall, where we can pass the signature for the kernel as a separate > file. Ideally also with a flags argument and perhaps the ability to sign > the initrd too.
Verifying root file system would be another topic in general.
> That way we don't ahve to come up with a magic vmlinux+signature format, > as we can just pass a regular image and a signature for that image > separately. That should work for PPC and others, too.
Since some discussions are to be expected around vmlinux signing, I will drop vmlinux support in v2.
(This means, as you mentioned, that we have no way to sign a !CONFIG_EFI kernel for now. The possible solution in future would be to utilize file extended attributes as proposed by powerpc guys?)
Thanks, -Takahiro AKASHI
> Thanks, > Mark.
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