signing.bbclass: add signing_get_intermediate_certs

Add a method that returns a list of intermediary CA roles.

When using a complex PKI structure with for example "openssl cms",
these roles can then be iterated over adding in turn a '-certificate'.
Pseudo-code example:
  for intermediate in $(signing_get_intermediate_certs 'FooBaa'); do
     signing_extract_cert_pem $intermediate $intermediate.pem
     CMD+=" --certificate=$intermediate.pem"
  done

The typical use-case would be adding these intermediate certificates
to the CMS structure so that the relying party can build the chain
from the signing leaf certificate to the locally stored trusted CA
certificate.

Reviewed-by: Jan Luebbe <jlu@pengutronix.de>
Signed-off-by: Johannes Schneider <johannes.schneider@leica-geosystems.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/meta-oe/classes/signing.bbclass b/meta-oe/classes/signing.bbclass
index 2a94f5f5b3..248c6400ed 100644
--- a/meta-oe/classes/signing.bbclass
+++ b/meta-oe/classes/signing.bbclass
@@ -194,6 +194,27 @@ signing_has_ca() {
     return $?
 }
 
+# signing_get_intermediate_certs <cert_name>
+#
+# return a list of role/name intermediary CA certificates for a given
+# <cert_name> by walking the chain setup with signing_import_set_ca.
+#
+# The returned list will not include the the root CA, and can
+# potentially be empty.
+#
+# To be used with SoftHSM.
+signing_get_intermediate_certs() {
+    local cert_name="${1}"
+    local intermediary=""
+    while signing_has_ca "${cert_name}"; do
+        cert_name="$(signing_get_ca ${cert_name})"
+        if signing_has_ca "${cert_name}"; then
+            intermediary="${intermediary} ${cert_name}"
+        fi
+    done
+    echo "${intermediary}"
+}
+
 # signing_get_root_cert <cert_name>
 #
 # return the role/name of the CA root certificate for a given