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From:   Stefan Berger <stefanb@linux.ibm.com>
To:     jeyu@kernel.org, keyrings@vger.kernel.org, dhowells@redhat.com,
        dwmw2@infradead.org, zohar@linux.ibm.com, jarkko@kernel.org
Cc:     nayna@linux.ibm.com, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, Stefan Berger <stefanb@linux.ibm.com>
Subject: [PATCH v6 1/4] certs: Trigger creation of RSA module signing key if it's not an RSA key
Date:   Thu, 10 Jun 2021 08:56:20 -0400
Message-Id: <20210610125623.1553792-2-stefanb@linux.ibm.com>
In-Reply-To: <20210610125623.1553792-1-stefanb@linux.ibm.com>
References: <20210610125623.1553792-1-stefanb@linux.ibm.com>
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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@linux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
 certs/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/certs/Makefile b/certs/Makefile
index 359239a0ee9e..e6f97c64aa99 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -62,6 +62,11 @@ 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