certs: check-in the default x509 config file

When x509.genkey is created, it prints a log:

  Generating X.509 key generation config

..., which is not the ordinary Kbuild log style.

Check-in the default config as certs/default_x509.genkey to make it
readable, and copy it to certs/x509.genkey if it is not present.

The log is shown in the Kbuild style.

  COPY    certs/x509.genkey
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

certs/Makefile

@@ -98,25 +98,13 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey
 	@$(kecho) "### Key pair generated."
 	@$(kecho) "###"
 
+quiet_cmd_copy_x509_config = COPY    $@
+      cmd_copy_x509_config = cat $(srctree)/$(src)/default_x509.genkey > $@
+
+# You can provide your own config file. If not present, copy the default one.
 $(obj)/x509.genkey:
-	@$(kecho) Generating X.509 key generation config
-	@echo  >$@ "[ req ]"
-	@echo >>$@ "default_bits = 4096"
-	@echo >>$@ "distinguished_name = req_distinguished_name"
-	@echo >>$@ "prompt = no"
-	@echo >>$@ "string_mask = utf8only"
-	@echo >>$@ "x509_extensions = myexts"
-	@echo >>$@
-	@echo >>$@ "[ req_distinguished_name ]"
-	@echo >>$@ "#O = Unspecified company"
-	@echo >>$@ "CN = Build time autogenerated kernel key"
-	@echo >>$@ "#emailAddress = unspecified.user@unspecified.company"
-	@echo >>$@
-	@echo >>$@ "[ myexts ]"
-	@echo >>$@ "basicConstraints=critical,CA:FALSE"
-	@echo >>$@ "keyUsage=digitalSignature"
-	@echo >>$@ "subjectKeyIdentifier=hash"
-	@echo >>$@ "authorityKeyIdentifier=keyid"
+	$(call cmd,copy_x509_config)
+
 endif # CONFIG_MODULE_SIG_KEY
 
 $(eval $(call config_filename,MODULE_SIG_KEY))

certs/default_x509.genkey

+[ req ]
+default_bits = 4096
+distinguished_name = req_distinguished_name
+prompt = no
+string_mask = utf8only
+x509_extensions = myexts
+
+[ req_distinguished_name ]
+#O = Unspecified company
+CN = Build time autogenerated kernel key
+#emailAddress = unspecified.user@unspecified.company
+
+[ myexts ]
+basicConstraints=critical,CA:FALSE
+keyUsage=digitalSignature
+subjectKeyIdentifier=hash
+authorityKeyIdentifier=keyid