[PATCH v2 2/5] keys: generate self-signed module signing key using CSR

[Nayna Jain]

Loading a key on the IMA trusted keyring requires the key be signed
by an existing key on the builtin or secondary trusted keyring.
Creating a Certificate Signing Request (CSR) allows the certificate
to be self-signed or signed by a CA.

Generate a self-signed module signing key using CSR.

Signed-off-by: Nayna Jain <nayna@xxxxxxxxxxxxx>
---
 Makefile       |  3 ++-
 certs/Makefile | 15 +++++++++++----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index 004163a4e6b3..a971d4ae40bd 100644
--- a/Makefile
+++ b/Makefile
@@ -1473,7 +1473,8 @@ MRPROPER_FILES += include/config include/generated          \
 		  .config .config.old .version \
 		  Module.symvers \
 		  certs/signing_key.pem certs/signing_key.x509 \
-		  certs/x509.genkey \
+		  certs/x509.genkey certs/signing_key.key \
+		  certs/signing_key.crt certs/signing_key.csr \
 		  vmlinux-gdb.py \
 		  *.spec
 
diff --git a/certs/Makefile b/certs/Makefile
index f4c25b67aad9..b2be7eb413d3 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -60,11 +60,18 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
 	@$(kecho) "### needs to be run as root, and uses a hardware random"
 	@$(kecho) "### number generator if one is available."
 	@$(kecho) "###"
-	$(Q)openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
-		-batch -x509 -config $(obj)/x509.genkey \
-		-outform PEM -out $(obj)/signing_key.pem \
-		-keyout $(obj)/signing_key.pem \
+	$(Q)openssl req -new -nodes -utf8 \
+		-batch -config $(obj)/x509.genkey \
+		-outform PEM -out $(obj)/signing_key.csr \
+		-keyout $(obj)/signing_key.key -extensions myexts \
 		$($(quiet)redirect_openssl)
+	$(Q)openssl x509 -req -days 36500 -in $(obj)/signing_key.csr \
+		-outform PEM -out $(obj)/signing_key.crt \
+		-signkey $(obj)/signing_key.key \
+		-$(CONFIG_MODULE_SIG_HASH) -extensions myexts \
+		-extfile $(obj)/x509.genkey \
+		$($(quiet)redirect_openssl)
+	@cat $(obj)/signing_key.key $(obj)/signing_key.crt >> $(obj)/signing_key.pem
 	@$(kecho) "###"
 	@$(kecho) "### Key pair generated."
 	@$(kecho) "###"
-- 
2.29.2