pubkey: handle X25519 and X448 in gnutls_pubkey_import_pkcs11

I am not confident in the strings I chose to match on in
ASN1_ETYPE_PRINTABLE_STRING, in that I do not know what registry
I should look this up in.

The *parse_ecc_ecdh_params and *import_ecc_ecdh functions are tweaked
analogs to the eddsa versions of those functions.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>

1 files changed, 137 insertions, 0 deletions

diff --git a/lib/pubkey.c b/lib/pubkey.c
index a1735cf766..6d00e87876 100644
--- a/lib/pubkey.c
+++ b/lib/pubkey.c
@@ -497,6 +497,139 @@ gnutls_pubkey_import_ecc_eddsa(gnutls_pubkey_t key,
 	return ret;
 }
 
+/* Same as above, but for Edwards key agreement */
+static int
+gnutls_pubkey_parse_ecc_ecdh_params(const gnutls_datum_t *parameters,
+                                    gnutls_ecc_curve_t *outcurve)
+{
+	gnutls_ecc_curve_t curve = GNUTLS_ECC_CURVE_INVALID;
+	ASN1_TYPE asn1 = ASN1_TYPE_EMPTY;
+	unsigned int etype = ASN1_ETYPE_INVALID;
+	char str[MAX_OID_SIZE];
+	int str_size;
+	int ret;
+
+	ret = asn1_create_element(_gnutls_get_gnutls_asn(),
+				  "GNUTLS.pkcs-11-ec-Parameters", &asn1);
+	if (ret != ASN1_SUCCESS) {
+		gnutls_assert();
+		return _gnutls_asn2err(ret);
+	}
+
+	ret = asn1_der_decoding(&asn1, parameters->data, parameters->size,
+				NULL);
+	if (ret != ASN1_SUCCESS) {
+		gnutls_assert();
+		ret = _gnutls_asn2err(ret);
+		goto cleanup;
+	}
+
+	/* Read the type of choice.
+	 */
+	str_size = sizeof(str) - 1;
+	ret = asn1_read_value(asn1, "", str, &str_size);
+	if (ret != ASN1_SUCCESS) {
+		gnutls_assert();
+		ret = _gnutls_asn2err(ret);
+		goto cleanup;
+	}
+	str[str_size] = 0;
+
+	/* Convert the choice to enum type */
+	if (strcmp(str, "oId") == 0) {
+		etype = ASN1_ETYPE_OBJECT_ID;
+	} else if (strcmp(str, "curveName") == 0) {
+		etype = ASN1_ETYPE_PRINTABLE_STRING;
+	}
+
+	str_size = sizeof(str) - 1;
+	switch (etype) {
+	case ASN1_ETYPE_OBJECT_ID:
+		ret = asn1_read_value(asn1, "oId", str, &str_size);
+		if (ret != ASN1_SUCCESS) {
+			gnutls_assert();
+			ret = _gnutls_asn2err(ret);
+			break;
+		}
+
+		curve = gnutls_oid_to_ecc_curve(str);
+		if (curve != GNUTLS_ECC_CURVE_X25519 &&
+		    curve != GNUTLS_ECC_CURVE_X448) {
+			_gnutls_debug_log("Curve %s is not supported for Edwards-based key agreement\n", str);
+			gnutls_assert();
+			curve = GNUTLS_ECC_CURVE_INVALID;
+			ret = GNUTLS_E_ECC_UNSUPPORTED_CURVE;
+			break;
+		}
+
+		ret = GNUTLS_E_SUCCESS;
+		break;
+
+	case ASN1_ETYPE_PRINTABLE_STRING:
+		ret = asn1_read_value(asn1, "curveName", str, &str_size);
+		if (ret != ASN1_SUCCESS) {
+			gnutls_assert();
+			ret = _gnutls_asn2err(ret);
+			break;
+		}
+
+		if (str_size == strlen("x25519") &&
+		    strncmp(str, "x25519", str_size) == 0) {
+			curve = GNUTLS_ECC_CURVE_X25519;
+			ret = GNUTLS_E_SUCCESS;
+			break;
+		} else if (str_size == strlen("x448") &&
+			   strncmp(str, "x448", str_size) == 0) {
+			curve = GNUTLS_ECC_CURVE_X448;
+			ret = GNUTLS_E_SUCCESS;
+			break;
+		}
+		/* FALLTHROUGH */
+
+	default:
+		/* Neither of CHOICEs found. Fail */
+		gnutls_assert();
+		ret = GNUTLS_E_ECC_UNSUPPORTED_CURVE;
+		curve = GNUTLS_ECC_CURVE_INVALID;
+		break;
+	}
+
+
+      cleanup:
+	asn1_delete_structure(&asn1);
+	*outcurve = curve;
+	return ret;
+}
+
+static int
+gnutls_pubkey_import_ecc_ecdh(gnutls_pubkey_t key,
+                              const gnutls_datum_t * parameters,
+                              const gnutls_datum_t * ecpoint)
+{
+	int ret;
+
+	gnutls_ecc_curve_t curve = GNUTLS_ECC_CURVE_INVALID;
+	gnutls_datum_t raw_point = {NULL, 0};
+
+	ret = gnutls_pubkey_parse_ecc_ecdh_params(parameters, &curve);
+	if (ret < 0) {
+		return gnutls_assert_val(ret);
+	}
+
+	ret = _gnutls_x509_decode_string(ASN1_ETYPE_OCTET_STRING,
+					 ecpoint->data, ecpoint->size,
+					 &raw_point, 0);
+	if (ret < 0) {
+		gnutls_assert();
+		gnutls_free(raw_point.data);
+		return ret;
+	}
+	ret = gnutls_pubkey_import_ecc_raw(key, curve, &raw_point, NULL);
+
+	gnutls_free(raw_point.data);
+	return ret;
+}
+
 /**
  * gnutls_pubkey_import_pkcs11:
  * @key: The public key
@@ -577,6 +710,10 @@ gnutls_pubkey_import_pkcs11(gnutls_pubkey_t key,
 		ret = gnutls_pubkey_import_ecc_eddsa(key, &obj->pubkey[0],
 						     &obj->pubkey[1]);
 		break;
+	case GNUTLS_PK_ECDH_X25519:
+		ret = gnutls_pubkey_import_ecc_ecdh(key, &obj->pubkey[0],
+                                                    &obj->pubkey[1]);
+		break;
 	default:
 		gnutls_assert();
 		return GNUTLS_E_UNIMPLEMENTED_FEATURE;