[PATCH v4 15/29] x509: move common functions to x509 helper

[Raymond Mao]

Move x509_check_for_self_signed as a common helper function
that can be shared by legacy crypto lib and MbedTLS implementation.

Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
---
Changes in v4
- Initial patch.

 lib/crypto/Makefile          |  1 +
 lib/crypto/x509_helper.c     | 67 ++++++++++++++++++++++++++++++++++++
 lib/crypto/x509_public_key.c | 56 +-----------------------------
 3 files changed, 69 insertions(+), 55 deletions(-)
 create mode 100644 lib/crypto/x509_helper.c

diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index 4ad1849040d..946cc3a7b59 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -37,6 +37,7 @@ x509_key_parser-y := \
 	x509.asn1.o \
 	x509_akid.asn1.o \
 	x509_cert_parser.o \
+	x509_helper.o \
 	x509_public_key.o
 
 $(obj)/x509_cert_parser.o: \
diff --git a/lib/crypto/x509_helper.c b/lib/crypto/x509_helper.c
new file mode 100644
index 00000000000..d0c80907ec3
--- /dev/null
+++ b/lib/crypto/x509_helper.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * X509 helper functions
+ *
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells at redhat.com)
+ *
+ * Copyright (c) 2024 Linaro Limited
+ * Author: Raymond Mao <raymond.mao at linaro.org>
+ */
+#include <linux/err.h>
+#include <crypto/public_key.h>
+#include <crypto/x509_parser.h>
+
+/*
+ * Check for self-signedness in an X.509 cert and if found, check the signature
+ * immediately if we can.
+ */
+int x509_check_for_self_signed(struct x509_certificate *cert)
+{
+	int ret = 0;
+
+	if (cert->raw_subject_size != cert->raw_issuer_size ||
+	    memcmp(cert->raw_subject, cert->raw_issuer,
+		   cert->raw_issuer_size))
+		goto not_self_signed;
+
+	if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
+		/*
+		 * If the AKID is present it may have one or two parts. If
+		 * both are supplied, both must match.
+		 */
+		bool a = asymmetric_key_id_same(cert->skid,
+						cert->sig->auth_ids[1]);
+		bool b = asymmetric_key_id_same(cert->id,
+						cert->sig->auth_ids[0]);
+
+		if (!a && !b)
+			goto not_self_signed;
+
+		ret = -EKEYREJECTED;
+		if (((a && !b) || (b && !a)) &&
+		    cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
+			goto out;
+	}
+
+	ret = -EKEYREJECTED;
+	if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo))
+		goto out;
+
+	ret = public_key_verify_signature(cert->pub, cert->sig);
+	if (ret == -ENOPKG) {
+		cert->unsupported_sig = true;
+		goto not_self_signed;
+	}
+	if (ret < 0)
+		goto out;
+
+	pr_devel("Cert Self-signature verified");
+	cert->self_signed = true;
+
+out:
+	return ret;
+
+not_self_signed:
+	return 0;
+}
diff --git a/lib/crypto/x509_public_key.c b/lib/crypto/x509_public_key.c
index a10145a7cdc..4ba13c1adc3 100644
--- a/lib/crypto/x509_public_key.c
+++ b/lib/crypto/x509_public_key.c
@@ -139,61 +139,7 @@ error:
 	return ret;
 }
 
-/*
- * Check for self-signedness in an X.509 cert and if found, check the signature
- * immediately if we can.
- */
-int x509_check_for_self_signed(struct x509_certificate *cert)
-{
-	int ret = 0;
-
-	pr_devel("==>%s()\n", __func__);
-
-	if (cert->raw_subject_size != cert->raw_issuer_size ||
-	    memcmp(cert->raw_subject, cert->raw_issuer,
-		   cert->raw_issuer_size) != 0)
-		goto not_self_signed;
-
-	if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
-		/* If the AKID is present it may have one or two parts.  If
-		 * both are supplied, both must match.
-		 */
-		bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
-		bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
-
-		if (!a && !b)
-			goto not_self_signed;
-
-		ret = -EKEYREJECTED;
-		if (((a && !b) || (b && !a)) &&
-		    cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
-			goto out;
-	}
-
-	ret = -EKEYREJECTED;
-	if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
-		goto out;
-
-	ret = public_key_verify_signature(cert->pub, cert->sig);
-	if (ret < 0) {
-		if (ret == -ENOPKG) {
-			cert->unsupported_sig = true;
-			ret = 0;
-		}
-		goto out;
-	}
-
-	pr_devel("Cert Self-signature verified");
-	cert->self_signed = true;
-
-out:
-	pr_devel("<==%s() = %d\n", __func__, ret);
-	return ret;
-
-not_self_signed:
-	pr_devel("<==%s() = 0 [not]\n", __func__);
-	return 0;
-}
+#endif /* !CONFIG_IS_ENABLED(MBEDTLS_LIB_X509) */
 
 #ifndef __UBOOT__
 /*
-- 
2.25.1