Re: [PATCH v2 0/3] initramfs: add support for xattrs in the initial ram disk

From: Rob Landley
Date: Tue May 14 2019 - 19:40:29 EST

On 5/14/19 2:18 PM, James Bottomley wrote:
>> I think Rob is right here. If /init was statically built into the
>> kernel image, it has no more ability to compromise the kernel than
>> anything else in the kernel. What's the problem here?
> The specific problem is that unless you own the kernel signing key,
> which is really untrue for most distribution consumers because the
> distro owns the key, you cannot build the initrd statically into the
> kernel. You can take the distro signed kernel, link it with the initrd
> then resign the combination with your key, provided you insert your key
> into the MoK variables as a trusted secure boot key, but the distros
> have been unhappy recommending this as standard practice.
> If our model for security is going to be to link the kernel and the
> initrd statically to give signature protection over the aggregate then
> we need to figure out how to execute this via the distros. If we
> accept that the split model, where the distro owns and signs the kernel
> but the machine owner builds and is responsible for the initrd, then we
> need to explore split security models like this proposal.

You can have a built-in and an external initrd? The second extracts over the
first? (I know because once upon a time conflicting files would append. It
sounds like the desired behavior here is O_EXCL fail and move on.)