1 files changed, 375 insertions, 0 deletions
diff --git a/src/libdnssec/key/convert.c b/src/libdnssec/key/convert.c
new file mode 100644
index 0000000..b8ebb7d
--- /dev/null
+++ b/src/libdnssec/key/convert.c
@@ -0,0 +1,375 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <assert.h>
+#include <gnutls/abstract.h>
+#include <gnutls/gnutls.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "libdnssec/shared/bignum.h"
+#include "libdnssec/binary.h"
+#include "libdnssec/error.h"
+#include "libdnssec/key.h"
+#include "libdnssec/key/algorithm.h"
+#include "libdnssec/key/dnskey.h"
+#include "libdnssec/shared/shared.h"
+#include "libdnssec/shared/binary_wire.h"
+
+/* -- wrappers for GnuTLS types -------------------------------------------- */
+
+static size_t bignum_size_u_datum(const gnutls_datum_t *_bignum)
+{
+	const dnssec_binary_t bignum = binary_from_datum(_bignum);
+	return bignum_size_u(&bignum);
+}
+
+static void wire_write_bignum_datum(wire_ctx_t *ctx, size_t width,
+				    const gnutls_datum_t *_bignum)
+{
+	const dnssec_binary_t bignum = binary_from_datum(_bignum);
+	bignum_write(ctx, width, &bignum);
+}
+
+static gnutls_datum_t wire_take_datum(wire_ctx_t *ctx, size_t count)
+{
+	gnutls_datum_t result = { .data = ctx->position, .size = count };
+	ctx->position += count;
+
+	return result;
+}
+
+/* -- DNSSEC to crypto ------------------------------------------------------*/
+
+/*!
+ * Convert RSA public key to DNSSEC format.
+ */
+static int rsa_pubkey_to_rdata(gnutls_pubkey_t key, dnssec_binary_t *rdata)
+{
+	assert(key);
+	assert(rdata);
+
+	_cleanup_datum_ gnutls_datum_t modulus = { 0 };
+	_cleanup_datum_ gnutls_datum_t exponent = { 0 };
+
+	int result = gnutls_pubkey_get_pk_rsa_raw(key, &modulus, &exponent);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_EXPORT_ERROR;
+	}
+
+	size_t exponent_size = bignum_size_u_datum(&exponent);
+	if (exponent_size > UINT8_MAX) {
+		return DNSSEC_KEY_EXPORT_ERROR;
+	}
+
+	size_t modulus_size = bignum_size_u_datum(&modulus);
+
+	result = dnssec_binary_alloc(rdata, 1 + exponent_size + modulus_size);
+	if (result != DNSSEC_EOK) {
+		return result;
+	}
+
+	wire_ctx_t wire = binary_init(rdata);
+	wire_ctx_write_u8(&wire, exponent_size);
+	wire_write_bignum_datum(&wire, exponent_size, &exponent);
+	wire_write_bignum_datum(&wire, modulus_size, &modulus);
+	assert(wire_ctx_offset(&wire) == rdata->size);
+
+	return DNSSEC_EOK;
+}
+
+/*!
+ * Get point size for an ECDSA curve.
+ */
+static size_t ecdsa_curve_point_size(gnutls_ecc_curve_t curve)
+{
+	switch (curve) {
+	case GNUTLS_ECC_CURVE_SECP256R1: return 32;
+	case GNUTLS_ECC_CURVE_SECP384R1: return 48;
+	default: return 0;
+	}
+}
+
+#if defined(HAVE_ED25519) || defined(HAVE_ED448)
+static size_t eddsa_curve_point_size(gnutls_ecc_curve_t curve)
+{
+	switch (curve) {
+#ifdef HAVE_ED25519
+	case GNUTLS_ECC_CURVE_ED25519: return 32;
+#endif
+#ifdef HAVE_ED448
+	case GNUTLS_ECC_CURVE_ED448: return 57;
+#endif
+	default: return 0;
+	}
+}
+#endif
+
+/*!
+ * Convert ECDSA public key to DNSSEC format.
+ */
+static int ecdsa_pubkey_to_rdata(gnutls_pubkey_t key, dnssec_binary_t *rdata)
+{
+	assert(key);
+	assert(rdata);
+
+	_cleanup_datum_ gnutls_datum_t point_x = { 0 };
+	_cleanup_datum_ gnutls_datum_t point_y = { 0 };
+	gnutls_ecc_curve_t curve = { 0 };
+
+	int result = gnutls_pubkey_get_pk_ecc_raw(key, &curve, &point_x, &point_y);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_EXPORT_ERROR;
+	}
+
+	size_t point_size = ecdsa_curve_point_size(curve);
+	if (point_size == 0) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	result = dnssec_binary_alloc(rdata, 2 * point_size);
+	if (result != DNSSEC_EOK) {
+		return result;
+	}
+
+	wire_ctx_t wire = binary_init(rdata);
+	wire_write_bignum_datum(&wire, point_size, &point_x);
+	wire_write_bignum_datum(&wire, point_size, &point_y);
+	assert(wire_ctx_offset(&wire) == rdata->size);
+
+	return DNSSEC_EOK;
+}
+
+/*!
+ * Convert EDDSA public key to DNSSEC format.
+ */
+#if defined(HAVE_ED25519) || defined(HAVE_ED448)
+static int eddsa_pubkey_to_rdata(gnutls_pubkey_t key, dnssec_binary_t *rdata)
+{
+	assert(key);
+	assert(rdata);
+
+	_cleanup_datum_ gnutls_datum_t point_x = { 0 };
+	gnutls_ecc_curve_t curve = { 0 };
+
+	int result = gnutls_pubkey_get_pk_ecc_raw(key, &curve, &point_x, NULL);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_EXPORT_ERROR;
+	}
+
+	size_t point_size = eddsa_curve_point_size(curve);
+	if (point_size == 0) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	result = dnssec_binary_alloc(rdata, point_size);
+	if (result != DNSSEC_EOK) {
+		return result;
+	}
+
+	wire_ctx_t wire = binary_init(rdata);
+	wire_write_bignum_datum(&wire, point_size, &point_x);
+	assert(wire_ctx_offset(&wire) == rdata->size);
+
+	return DNSSEC_EOK;
+}
+#endif
+
+/* -- crypto to DNSSEC ------------------------------------------------------*/
+
+/*!
+ * Convert RSA key in DNSSEC format to crypto key.
+ */
+static int rsa_rdata_to_pubkey(const dnssec_binary_t *rdata, gnutls_pubkey_t key)
+{
+	assert(rdata);
+	assert(key);
+
+	if (rdata->size == 0) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	wire_ctx_t ctx = binary_init(rdata);
+
+	// parse public exponent
+
+	uint8_t exponent_size = wire_ctx_read_u8(&ctx);
+	if (exponent_size == 0 || wire_ctx_available(&ctx) < exponent_size) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	gnutls_datum_t exponent = wire_take_datum(&ctx, exponent_size);
+
+	// parse modulus
+
+	size_t modulus_size = wire_ctx_available(&ctx);
+	if (modulus_size == 0) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	gnutls_datum_t modulus = wire_take_datum(&ctx, modulus_size);
+
+	assert(wire_ctx_offset(&ctx) == rdata->size);
+
+	int result = gnutls_pubkey_import_rsa_raw(key, &modulus, &exponent);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_IMPORT_ERROR;
+	}
+
+	return DNSSEC_EOK;
+}
+
+/**
+ * Get ECDSA curve based on DNSKEY RDATA size.
+ */
+static gnutls_ecc_curve_t ecdsa_curve_from_rdata_size(size_t rdata_size)
+{
+	switch (rdata_size) {
+	case 64: return GNUTLS_ECC_CURVE_SECP256R1;
+	case 96: return GNUTLS_ECC_CURVE_SECP384R1;
+	default: return GNUTLS_ECC_CURVE_INVALID;
+	}
+}
+
+/**
+ * Get EDDSA curve based on DNSKEY RDATA size.
+ */
+#if defined(HAVE_ED25519) || defined(HAVE_ED448)
+static gnutls_ecc_curve_t eddsa_curve_from_rdata_size(size_t rdata_size)
+{
+	switch (rdata_size) {
+#ifdef HAVE_ED25519
+	case 32: return GNUTLS_ECC_CURVE_ED25519;
+#endif
+#ifdef HAVE_ED448
+	case 57: return GNUTLS_ECC_CURVE_ED448;
+#endif
+	default: return GNUTLS_ECC_CURVE_INVALID;
+	}
+}
+#endif
+
+/*!
+ * Convert ECDSA key in DNSSEC format to crypto key.
+ */
+static int ecdsa_rdata_to_pubkey(const dnssec_binary_t *rdata, gnutls_pubkey_t key)
+{
+	assert(rdata);
+	assert(key);
+
+	gnutls_ecc_curve_t curve = ecdsa_curve_from_rdata_size(rdata->size);
+	if (curve == GNUTLS_ECC_CURVE_INVALID) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	// parse points
+
+	wire_ctx_t ctx = binary_init(rdata);
+
+	size_t point_size = wire_ctx_available(&ctx) / 2;
+	gnutls_datum_t point_x = wire_take_datum(&ctx, point_size);
+	gnutls_datum_t point_y = wire_take_datum(&ctx, point_size);
+	assert(wire_ctx_offset(&ctx) == rdata->size);
+
+	int result = gnutls_pubkey_import_ecc_raw(key, curve, &point_x, &point_y);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_IMPORT_ERROR;
+	}
+
+	return DNSSEC_EOK;
+}
+
+/*!
+ * Convert EDDSA key in DNSSEC format to crypto key.
+ */
+#if defined(HAVE_ED25519) || defined(HAVE_ED448)
+static int eddsa_rdata_to_pubkey(const dnssec_binary_t *rdata, gnutls_pubkey_t key)
+{
+	assert(rdata);
+	assert(key);
+
+	gnutls_ecc_curve_t curve = eddsa_curve_from_rdata_size(rdata->size);
+	if (curve == GNUTLS_ECC_CURVE_INVALID) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	wire_ctx_t ctx = binary_init(rdata);
+
+	size_t point_size = wire_ctx_available(&ctx);
+	gnutls_datum_t point_x = wire_take_datum(&ctx, point_size);
+	assert(wire_ctx_offset(&ctx) == rdata->size);
+
+	int result = gnutls_pubkey_import_ecc_raw(key, curve, &point_x, NULL);
+	if (result != GNUTLS_E_SUCCESS) {
+		return DNSSEC_KEY_IMPORT_ERROR;
+	}
+
+	return DNSSEC_EOK;
+}
+#endif
+
+/* -- internal API --------------------------------------------------------- */
+
+/*!
+ * Encode public key to the format used in DNSKEY RDATA.
+ */
+int convert_pubkey_to_dnskey(gnutls_pubkey_t key, dnssec_binary_t *rdata)
+{
+	assert(key);
+	assert(rdata);
+
+	int algorithm = gnutls_pubkey_get_pk_algorithm(key, NULL);
+	if (algorithm < 0) {
+		return DNSSEC_INVALID_PUBLIC_KEY;
+	}
+
+	switch ((gnutls_pk_algorithm_t)algorithm) {
+	case GNUTLS_PK_RSA: return rsa_pubkey_to_rdata(key, rdata);
+	case GNUTLS_PK_EC:  return ecdsa_pubkey_to_rdata(key, rdata);
+#ifdef HAVE_ED25519
+	case GNUTLS_PK_EDDSA_ED25519: return eddsa_pubkey_to_rdata(key, rdata);
+#endif
+#ifdef HAVE_ED448
+	case GNUTLS_PK_EDDSA_ED448: return eddsa_pubkey_to_rdata(key, rdata);
+#endif
+	default: return DNSSEC_INVALID_KEY_ALGORITHM;
+	}
+}
+
+/*!
+ * Create public key from the format encoded in DNSKEY RDATA.
+ */
+int convert_dnskey_to_pubkey(uint8_t algorithm, const dnssec_binary_t *rdata,
+			     gnutls_pubkey_t key)
+{
+	assert(rdata);
+	assert(key);
+
+	gnutls_pk_algorithm_t gnutls_alg = algorithm_to_gnutls(algorithm);
+
+	switch(gnutls_alg) {
+	case GNUTLS_PK_RSA: return rsa_rdata_to_pubkey(rdata, key);
+	case GNUTLS_PK_EC:  return ecdsa_rdata_to_pubkey(rdata, key);
+#ifdef HAVE_ED25519
+	case GNUTLS_PK_EDDSA_ED25519: return eddsa_rdata_to_pubkey(rdata, key);
+#endif
+#ifdef HAVE_ED448
+	case GNUTLS_PK_EDDSA_ED448: return eddsa_rdata_to_pubkey(rdata, key);
+#endif
+	default: return DNSSEC_INVALID_KEY_ALGORITHM;
+	}
+}