[PATCH v3 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

[Jarkko Sakkinen]

On Wed, Apr 21, 2021 at 03:43:18PM -0400, Stefan Berger wrote:
> Address a kbuild issue where a developer created an ECDSA key for signing
> kernel modules and then builds an older version of the kernel, when bi-
> secting the kernel for example, that does not support ECDSA keys.
> 
> Trigger the creation of an RSA module signing key if it is not an RSA key.
> 
> Fixes: cfc411e7fff3 ("Move certificate handling to its own directory")
> Signed-off-by: Stefan Berger <stefanb at linux.ibm.com>

Reviewed-by: Jarkko Sakkinen <jarkko at kernel.org>

> ---
>  certs/Makefile | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/certs/Makefile b/certs/Makefile
> index e3185c57fbd8..f64bc89ccbf1 100644
> --- a/certs/Makefile
> +++ b/certs/Makefile
> @@ -59,6 +59,11 @@ silent_redirect_openssl = 2>/dev/null
>  # external private key, because 'make randconfig' might enable such a
>  # boolean option and we unfortunately can't make it depend on !RANDCONFIG.
>  ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem")
> +
> +X509TEXT=$(shell openssl x509 -in $(CONFIG_MODULE_SIG_KEY) -text)
> +
> +$(if $(findstring rsaEncryption,$(X509TEXT)),,$(shell rm -f $(CONFIG_MODULE_SIG_KEY)))
> +
>  $(obj)/signing_key.pem: $(obj)/x509.genkey
>  	@$(kecho) "###"
>  	@$(kecho) "### Now generating an X.509 key pair to be used for signing modules."
> -- 
> 2.29.2
> 
> 

/Jarkko