[PATCH v1] kernel-fit-image: Check signing key files based on algorithm

[Jamin Lin <jamin_lin@aspeedtech.com>]

The key file validation in run_mkimage_sign() unconditionally required
.key and .crt regardless of the signing algorithm. This prevented ECDSA
signing which uses a single .pem file.

Extract the check into _check_sign_key_files() and detect the algorithm
from the algo string (e.g. "sha256,ecdsa384") by scanning all
comma-separated parts so field order does not matter:
- ECDSA: requires <keyname>.pem
- RSA  : requires <keyname>.key and <keyname>.crt

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 meta/lib/oe/fitimage.py | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/meta/lib/oe/fitimage.py b/meta/lib/oe/fitimage.py
index 881d0eae0a..e6ff66ca43 100644
--- a/meta/lib/oe/fitimage.py
+++ b/meta/lib/oe/fitimage.py
@@ -574,6 +574,18 @@ class ItsNodeRootKernel(ItsNode):
         except subprocess.CalledProcessError as e:
             bb.fatal(f"Command '{' '.join(cmd)}' failed with return code {e.returncode}\nstdout: {e.stdout.decode()}\nstderr: {e.stderr.decode()}\nitsflile: {os.path.abspath(itsfile)}")
 
+    def _check_sign_key_files(self, key_path, algo):
+        """Check signing key files: ECDSA needs .pem, RSA needs .key + .crt."""
+        algo_parts = [p.strip().lower() for p in algo.split(',')]
+        is_ecdsa = any(p.startswith('ecdsa') for p in algo_parts)
+
+        if is_ecdsa:
+            if not os.path.exists(key_path + '.pem'):
+                bb.fatal("ECDSA signing requires '%s.pem'" % key_path)
+        else:
+            if not os.path.exists(key_path + '.key') or not os.path.exists(key_path + '.crt'):
+                bb.fatal("%s.key or .crt does not exist" % key_path)
+
     def run_mkimage_sign(self, fitfile):
         if not self._sign_enable:
             bb.debug(1, "FIT image signing is disabled. Skipping signing.")
@@ -581,12 +593,10 @@ class ItsNodeRootKernel(ItsNode):
 
         # Some sanity checks because mkimage exits with 0 also without needed keys
         sign_key_path = os.path.join(self._sign_keydir, self._sign_keyname_conf)
-        if not os.path.exists(sign_key_path + '.key') or not os.path.exists(sign_key_path + '.crt'):
-            bb.fatal("%s.key or .crt does not exist" % sign_key_path)
+        self._check_sign_key_files(sign_key_path, self._sign_algo)
         if self._sign_individual:
             sign_key_img_path = os.path.join(self._sign_keydir, self._sign_keyname_img)
-            if not os.path.exists(sign_key_img_path + '.key') or not os.path.exists(sign_key_img_path + '.crt'):
-                bb.fatal("%s.key or .crt does not exist" % sign_key_img_path)
+            self._check_sign_key_files(sign_key_img_path, self._sign_algo)
 
         cmd = [
             self._mkimage_sign,
-- 
2.43.0