[crypto] Allow for OID-identified elliptic curve algorithms

Elliptic curves in X.509 certificates are identified via the
id-ecPublicKey object identifier (1.2.840.10045.2.1), with the
specific elliptic curve identified via a second OID in the algorithm
parameters.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Author: mcb30

src/crypto/asn1.c

@@ -83,6 +83,19 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define EINFO_ENOTTY_ALGORITHM \
 	__einfo_uniqify ( EINFO_ENOTTY, 0x01, "Inappropriate algorithm" )
 
+/** "ecPublicKey" object identifier */
+static uint8_t oid_ecpublickey[] = { ASN1_OID_ECPUBLICKEY };
+
+/** Generic elliptic curve container algorithm
+ *
+ * The actual curve to be used is identified via the algorithm
+ * parameters, rather than the top-level OID.
+ */
+struct asn1_algorithm ecpubkey_algorithm __asn1_algorithm = {
+	.name = "ecPublicKey",
+	.oid = ASN1_CURSOR ( oid_ecpublickey ),
+};
+
 /**
  * Start parsing ASN.1 object
  *
@@ -624,20 +637,66 @@ int asn1_signature_algorithm ( const struct asn1_cursor *cursor,
 	return 0;
 }
 
+/**
+ * Parse ASN.1 OID-identified elliptic curve algorithm
+ *
+ * @v cursor		ASN.1 object cursor
+ * @ret algorithm	Algorithm
+ * @ret rc		Return status code
+ */
+int asn1_curve_algorithm ( const struct asn1_cursor *cursor,
+			   struct asn1_algorithm **algorithm ) {
+	struct asn1_cursor curve;
+
+	/* Elliptic curves are identified as either:
+	 *
+	 * - the algorithm "id-ecPublicKey" with the actual curve
+	 *   specified in the algorithm parameters, or
+	 *
+	 * - a standalone object identifier for the curve
+	 */
+	if ( asn1_check_algorithm ( cursor, &ecpubkey_algorithm,
+				    &curve ) != 0 ) {
+		memcpy ( &curve, cursor, sizeof ( curve ) );
+	}
+
+	/* Identify curve */
+	asn1_enter ( &curve, ASN1_OID );
+	*algorithm = asn1_find_algorithm ( &curve );
+	if ( ! *algorithm ) {
+		DBGC ( cursor, "ASN1 %p unrecognised EC algorithm:\n",
+		       cursor );
+		DBGC_HDA ( cursor, 0, cursor->data, cursor->len );
+		return -ENOTSUP_ALGORITHM;
+	}
+
+	/* Check algorithm has an elliptic curve */
+	if ( ! (*algorithm)->curve ) {
+		DBGC ( cursor, "ASN1 %p algorithm %s is not an elliptic curve "
+		       "algorithm:\n", cursor, (*algorithm)->name );
+		DBGC_HDA ( cursor, 0, cursor->data, cursor->len );
+		return -ENOTTY_ALGORITHM;
+	}
+
+	return 0;
+}
+
 /**
  * Check ASN.1 OID-identified algorithm
  *
  * @v cursor		ASN.1 object cursor
  * @v expected		Expected algorithm
+ * @ret params		Algorithm parameters, or NULL
  * @ret rc		Return status code
  */
 int asn1_check_algorithm ( const struct asn1_cursor *cursor,
-			   struct asn1_algorithm *expected ) {
+			   struct asn1_algorithm *expected,
+			   struct asn1_cursor *params ) {
 	struct asn1_algorithm *actual;
 	int rc;
 
 	/* Parse algorithm */
-	if ( ( rc = asn1_algorithm ( cursor, &actual, NULL ) ) != 0 )
+	if ( ( rc = asn1_algorithm ( cursor, &actual, params ) ) != 0 )
 		return rc;
 
 	/* Check algorithm matches */

src/crypto/rsa.c

@@ -194,8 +194,8 @@ static int rsa_parse_mod_exp ( struct asn1_cursor *modulus,
 		asn1_skip_any ( &cursor );
 
 		/* Enter privateKey, if present */
-		if ( asn1_check_algorithm ( &cursor,
-					    &rsa_encryption_algorithm ) == 0 ) {
+		if ( asn1_check_algorithm ( &cursor, &rsa_encryption_algorithm,
+					    NULL ) == 0 ) {
 
 			/* Skip privateKeyAlgorithm */
 			asn1_skip_any ( &cursor );

src/include/ipxe/asn1.h

@@ -127,9 +127,15 @@ struct asn1_builder_header {
 #define ASN1_OID_TRIPLE( value ) \
 	( 0x80 | ( ( (value) >> 14 ) & 0x7f ) ), ASN1_OID_DOUBLE ( (value) )
 
+/** ASN.1 OID for ecPublicKey (1.2.840.10045.2.1) */
+#define ASN1_OID_ECPUBLICKEY					\
+	ASN1_OID_INITIAL ( 1, 2 ), ASN1_OID_DOUBLE ( 840 ),	\
+	ASN1_OID_DOUBLE ( 10045 ), ASN1_OID_SINGLE ( 2 ),	\
+	ASN1_OID_SINGLE ( 1 )
+
 /** ASN.1 OID for prime256v1 (1.2.840.10045.3.1.7) */
 #define ASN1_OID_PRIME256V1					\
-	ASN1_OID_INITIAL ( 1, 1 ), ASN1_OID_DOUBLE ( 840 ),	\
+	ASN1_OID_INITIAL ( 1, 2 ), ASN1_OID_DOUBLE ( 840 ),	\
 	ASN1_OID_DOUBLE ( 10045 ), ASN1_OID_SINGLE ( 3 ),	\
 	ASN1_OID_SINGLE ( 1 ), ASN1_OID_SINGLE ( 7 )
 
@@ -426,6 +432,7 @@ extern struct asn1_algorithm oid_sha512_algorithm __asn1_algorithm;
 extern struct asn1_algorithm oid_sha224_algorithm __asn1_algorithm;
 extern struct asn1_algorithm oid_sha512_224_algorithm __asn1_algorithm;
 extern struct asn1_algorithm oid_sha512_256_algorithm __asn1_algorithm;
+extern struct asn1_algorithm ecpubkey_algorithm __asn1_algorithm;
 
 /**
  * Invalidate ASN.1 object cursor
@@ -497,8 +504,11 @@ extern int asn1_cipher_algorithm ( const struct asn1_cursor *cursor,
 				   struct asn1_cursor *params );
 extern int asn1_signature_algorithm ( const struct asn1_cursor *cursor,
 				      struct asn1_algorithm **algorithm );
+extern int asn1_curve_algorithm ( const struct asn1_cursor *cursor,
+				  struct asn1_algorithm **algorithm );
 extern int asn1_check_algorithm ( const struct asn1_cursor *cursor,
-				  struct asn1_algorithm *expected );
+				  struct asn1_algorithm *expected,
+				  struct asn1_cursor *params );
 extern int asn1_parse_cbc ( struct asn1_algorithm *algorithm,
 			    struct asn1_cursor *params );
 extern int asn1_parse_gcm ( struct asn1_algorithm *algorithm,