2021-04-23 15:15:32

by Stefan Berger

Subject: [PATCH v4 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

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 <[email protected]>
---
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

2021-05-31 17:05:55

by Mimi Zohar

Subject: Re: [PATCH v4 1/2] certs: Trigger creation of RSA module signing key if it's not an RSA key

On Fri, 2021-04-23 at 11:12 -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 <[email protected]>

Tested-by: Mimi Zohar <[email protected]>