------- Comment From daniel.axte...@ibm.com 2020-12-17 19:59 EDT-------
I checked out LP: #1643652. I don't know why we asked for IMA_X509_PATH there, 
we don't need it for OpenPower secure boot.

For guest secure boot, the end goal of my request here is to get the
pieces in place to enable signed kexec - at least for the kdump case.
Under secure boot, only signed kernels can be kexeced. The kernel will
verify the appended signature against the .platform and .ima keyrings.
The .platform keyring is fine on OpenPower secure boot and UEFI secure
boot because the keyring gets populated by keys out of firmware.
However, at the moment pseries firmware doesn't have any mechanism to
expose trusted keys (this will change with the full key management
solution!), so nothing ends up in .platform. So we want to get a key
into the .ima keychain instead.

IMA_X509_PATH purports to achieve this, but unfortunately just setting
it isn't quite sufficient. The key will only be loaded into the .ima
keychain if it's signed by a key already trusted by the kernel, that is,
in .builtin_trusted_keys.

(I discovered recently that it's also possible to load a key into .ima
at runtime with keyctl, so loading the key as part of the kexec scripts
could be an alternative. However, this also requires that the key being
loaded into .ima be trusted by the kernel.)

So, what I think I need is:

- the key that signs the kernel on the filesystem so that it can be
loaded by IMA_X509_PATH or keyctl.

- the CA key that signs the kernel-signing key to be trusted by the
kernel by being included in the .pem file that gets loaded by
CONFIG_SYSTEM_TRUSTED_KEYS.

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https://bugs.launchpad.net/bugs/1903288

Title:
  Power guest secure boot with static keys: kernel portion

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