1 files changed, 495 insertions, 0 deletions

diff --git a/src/utils/common/tls.c b/src/utils/common/tls.c
new file mode 100644
index 0000000..91b747f
--- /dev/null
+++ b/src/utils/common/tls.c
@@ -0,0 +1,495 @@
+/*  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 <arpa/inet.h>
+#include <stdbool.h>
+#include <string.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/x509.h>
+#include <poll.h>
+
+#include "utils/common/tls.h"
+#include "utils/common/cert.h"
+#include "utils/common/msg.h"
+#include "contrib/base64.h"
+#include "libknot/errcode.h"
+
+void tls_params_init(tls_params_t *params)
+{
+	if (params == NULL) {
+		return;
+	}
+
+	memset(params, 0, sizeof(*params));
+
+	init_list(&params->ca_files);
+	init_list(&params->pins);
+}
+
+int tls_params_copy(tls_params_t *dst, const tls_params_t *src)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	tls_params_init(dst);
+
+	dst->enable = src->enable;
+	dst->system_ca = src->system_ca;
+	if (src->hostname != NULL) {
+		dst->hostname = strdup(src->hostname);
+		if (dst->hostname == NULL) {
+			tls_params_clean(dst);
+			return KNOT_ENOMEM;
+		}
+	}
+
+	if (src->sni != NULL) {
+		dst->sni = strdup(src->sni);
+		if (dst->sni == NULL) {
+			tls_params_clean(dst);
+			return KNOT_ENOMEM;
+		}
+	}
+
+	ptrnode_t *n = NULL;
+	WALK_LIST(n, src->ca_files) {
+		char *src_file = (char *)n->d;
+		char *file = strdup(src_file);
+		if (file == NULL || ptrlist_add(&dst->ca_files, file, NULL) == NULL) {
+			tls_params_clean(dst);
+			return KNOT_ENOMEM;
+		}
+	}
+	WALK_LIST(n, src->pins) {
+		uint8_t *src_pin = (uint8_t *)n->d;
+		uint8_t *pin = malloc(1 + src_pin[0]);
+		if (pin == NULL || ptrlist_add(&dst->pins, pin, NULL) == NULL) {
+			tls_params_clean(dst);
+			return KNOT_ENOMEM;
+		}
+		memcpy(pin, src_pin, 1 + src_pin[0]);
+	}
+
+	return KNOT_EOK;
+}
+
+void tls_params_clean(tls_params_t *params)
+{
+	if (params == NULL) {
+		return;
+	}
+
+	ptrnode_t *node = NULL, *nxt = NULL;
+	WALK_LIST_DELSAFE(node, nxt, params->ca_files) {
+		free(node->d);
+	}
+	ptrlist_free(&params->ca_files, NULL);
+
+	WALK_LIST_DELSAFE(node, nxt, params->pins) {
+		free(node->d);
+	}
+	ptrlist_free(&params->pins, NULL);
+
+	free(params->hostname);
+	free(params->sni);
+
+	memset(params, 0, sizeof(*params));
+}
+
+static bool check_pin(const uint8_t *cert_pin, size_t cert_pin_len, const list_t *pins)
+{
+	if (EMPTY_LIST(*pins)) {
+		return false;
+	}
+
+	ptrnode_t *n = NULL;
+	WALK_LIST(n, *pins) {
+		uint8_t *pin = (uint8_t *)n->d;
+		if (pin[0] == cert_pin_len &&
+		    memcmp(cert_pin, &pin[1], cert_pin_len) == 0) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static int check_certificates(gnutls_session_t session, const list_t *pins)
+{
+	if (gnutls_certificate_type_get(session) != GNUTLS_CRT_X509) {
+		DBG("TLS, invalid certificate type\n");
+		return GNUTLS_E_CERTIFICATE_ERROR;
+	}
+
+	unsigned cert_list_size;
+	const gnutls_datum_t *cert_list =
+		gnutls_certificate_get_peers(session, &cert_list_size);
+	if (cert_list == NULL || cert_list_size == 0) {
+		DBG("TLS, empty certificate list\n");
+		return GNUTLS_E_CERTIFICATE_ERROR;
+	}
+
+	size_t matches = 0;
+
+	DBG("TLS, received certificate hierarchy:\n");
+	for (int i = 0; i < cert_list_size; i++) {
+		gnutls_x509_crt_t cert;
+		int ret = gnutls_x509_crt_init(&cert);
+		if (ret != GNUTLS_E_SUCCESS) {
+			return ret;
+		}
+
+		ret = gnutls_x509_crt_import(cert, &cert_list[i], GNUTLS_X509_FMT_DER);
+		if (ret != GNUTLS_E_SUCCESS) {
+			gnutls_x509_crt_deinit(cert);
+			return ret;
+		}
+
+		gnutls_datum_t cert_name = { 0 };
+		ret = gnutls_x509_crt_get_dn2(cert, &cert_name);
+		if (ret != GNUTLS_E_SUCCESS) {
+			gnutls_x509_crt_deinit(cert);
+			return ret;
+		}
+		DBG(" #%i, %s\n", i + 1, cert_name.data);
+		gnutls_free(cert_name.data);
+
+		uint8_t cert_pin[CERT_PIN_LEN] = { 0 };
+		ret = cert_get_pin(cert, cert_pin, sizeof(cert_pin));
+		if (ret != KNOT_EOK) {
+			gnutls_x509_crt_deinit(cert);
+			return GNUTLS_E_CERTIFICATE_ERROR;
+		}
+
+		// Check if correspond to a specified PIN.
+		bool match = check_pin(cert_pin, sizeof(cert_pin), pins);
+		if (match) {
+			matches++;
+		}
+
+		uint8_t *txt_pin;
+		ret = base64_encode_alloc(cert_pin, sizeof(cert_pin), &txt_pin);
+		if (ret < 0) {
+			gnutls_x509_crt_deinit(cert);
+			return ret;
+		}
+		DBG("     SHA-256 PIN: %.*s%s\n", ret, txt_pin, match ? ", MATCH" : "");
+		free(txt_pin);
+
+		gnutls_x509_crt_deinit(cert);
+	}
+
+	if (matches > 0) {
+		return GNUTLS_E_SUCCESS;
+	} else if (EMPTY_LIST(*pins)) {
+		DBG("TLS, skipping certificate PIN check\n");
+		return GNUTLS_E_SUCCESS;
+	} else {
+		DBG("TLS, no certificate PIN match\n");
+		return GNUTLS_E_CERTIFICATE_ERROR;
+	}
+}
+
+static bool do_verification(const tls_params_t *params)
+{
+	return params->hostname != NULL || params->system_ca ||
+	       !EMPTY_LIST(params->ca_files);
+}
+
+static int verify_certificate(gnutls_session_t session)
+{
+	tls_ctx_t *ctx = gnutls_session_get_ptr(session);
+
+	// Check for pinned certificates and print certificate hierarchy.
+	int ret = check_certificates(session, &ctx->params->pins);
+	if (ret != GNUTLS_E_SUCCESS) {
+		return ret;
+	}
+
+	if (!do_verification(ctx->params)) {
+		DBG("TLS, skipping certificate verification\n");
+		return GNUTLS_E_SUCCESS;
+	}
+
+	// Set server certificate check.
+	gnutls_typed_vdata_st data[2] = {
+		{ .type = GNUTLS_DT_KEY_PURPOSE_OID,
+		  .data = (void *)GNUTLS_KP_TLS_WWW_SERVER },
+		{ .type = GNUTLS_DT_DNS_HOSTNAME,
+		  .data = (void *)ctx->params->hostname }
+	};
+	size_t data_count = (ctx->params->hostname != NULL) ? 2 : 1;
+	if (data_count == 1) {
+		WARN("TLS, no hostname provided, will not verify certificate owner\n")
+	}
+
+	unsigned int status;
+	ret = gnutls_certificate_verify_peers(session, data, data_count, &status);
+	if (ret != GNUTLS_E_SUCCESS) {
+		WARN("TLS, failed to verify peer certificate\n");
+		return GNUTLS_E_CERTIFICATE_ERROR;
+	}
+
+	gnutls_datum_t msg;
+	ret = gnutls_certificate_verification_status_print(
+		status, gnutls_certificate_type_get(session), &msg, 0);
+	if (ret == GNUTLS_E_SUCCESS) {
+		DBG("TLS, %s\n", msg.data);
+	}
+	gnutls_free(msg.data);
+
+	return (status == 0) ? GNUTLS_E_SUCCESS : GNUTLS_E_CERTIFICATE_ERROR;
+}
+
+int tls_ctx_init(tls_ctx_t *ctx, const tls_params_t *params, int wait)
+{
+	if (ctx == NULL || params == NULL || !params->enable) {
+		return KNOT_EINVAL;
+	}
+
+	memset(ctx, 0, sizeof(*ctx));
+	ctx->params = params;
+	ctx->wait = wait;
+	ctx->sockfd = -1;
+
+	int ret = gnutls_certificate_allocate_credentials(&ctx->credentials);
+	if (ret != GNUTLS_E_SUCCESS) {
+		return KNOT_ENOMEM;
+	}
+
+	// Import system certificates.
+	if (ctx->params->system_ca ||
+	    (ctx->params->hostname != NULL && EMPTY_LIST(ctx->params->ca_files))) {
+		ret = gnutls_certificate_set_x509_system_trust(ctx->credentials);
+		if (ret < 0) {
+			WARN("TLS, failed to import system certificates (%s)\n",
+			     gnutls_strerror_name(ret));
+			return KNOT_ERROR;
+		} else {
+			DBG("TLS, imported %i system certificates\n", ret);
+		}
+	}
+
+	// Import provided certificate files.
+	ptrnode_t *n = NULL;
+	WALK_LIST(n, ctx->params->ca_files) {
+		const char *file = (char *)n->d;
+		ret = gnutls_certificate_set_x509_trust_file(ctx->credentials, file,
+		                                             GNUTLS_X509_FMT_PEM);
+		if (ret < 0) {
+			WARN("TLS, failed to import certificate file '%s' (%s)\n",
+			    file, gnutls_strerror_name(ret));
+			return KNOT_ERROR;
+		} else {
+			DBG("TLS, imported %i certificates from '%s'\n", ret, file);
+		}
+	}
+
+	gnutls_certificate_set_verify_function(ctx->credentials, verify_certificate);
+
+	return KNOT_EOK;
+}
+
+int tls_ctx_connect(tls_ctx_t *ctx, int sockfd,  const char *remote)
+{
+	if (ctx == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = gnutls_init(&ctx->session, GNUTLS_CLIENT | GNUTLS_NONBLOCK);
+	if (ret != GNUTLS_E_SUCCESS) {
+		return KNOT_NET_ECONNECT;
+	}
+
+	ret = gnutls_set_default_priority(ctx->session);
+	if (ret != GNUTLS_E_SUCCESS) {
+		return KNOT_NET_ECONNECT;
+	}
+
+	ret = gnutls_credentials_set(ctx->session, GNUTLS_CRD_CERTIFICATE,
+	                             ctx->credentials);
+	if (ret != GNUTLS_E_SUCCESS) {
+		return KNOT_NET_ECONNECT;
+	}
+
+	if (remote != NULL) {
+		ret = gnutls_server_name_set(ctx->session, GNUTLS_NAME_DNS, remote,
+		                             strlen(remote));
+		if (ret != GNUTLS_E_SUCCESS) {
+			return KNOT_NET_ECONNECT;
+		}
+	}
+
+	gnutls_session_set_ptr(ctx->session, ctx);
+	gnutls_transport_set_int(ctx->session, sockfd);
+	gnutls_handshake_set_timeout(ctx->session, 1000 * ctx->wait);
+
+	// Initialize poll descriptor structure.
+	struct pollfd pfd = {
+		.fd = sockfd,
+		.events = POLLIN,
+		.revents = 0,
+	};
+
+	// Perform the TLS handshake
+	do {
+		ret = gnutls_handshake(ctx->session);
+		if (ret != GNUTLS_E_SUCCESS && gnutls_error_is_fatal(ret) == 0) {
+			if (poll(&pfd, 1, 1000 * ctx->wait) != 1) {
+				WARN("TLS, peer took too long to respond\n");
+				return KNOT_NET_ETIMEOUT;
+			}
+		}
+	} while (ret != GNUTLS_E_SUCCESS && gnutls_error_is_fatal(ret) == 0);
+	if (ret != GNUTLS_E_SUCCESS) {
+		WARN("TLS, handshake failed (%s)\n", gnutls_strerror(ret));
+		tls_ctx_close(ctx);
+		return KNOT_NET_ESOCKET;
+	}
+
+	// Save the socket descriptor.
+	ctx->sockfd = sockfd;
+
+	return KNOT_EOK;
+}
+
+int tls_ctx_send(tls_ctx_t *ctx, const uint8_t *buf, const size_t buf_len)
+{
+	if (ctx == NULL || buf == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	uint16_t msg_len = htons(buf_len);
+
+	gnutls_record_cork(ctx->session);
+
+	if (gnutls_record_send(ctx->session, &msg_len, sizeof(msg_len)) <= 0) {
+		WARN("TLS, failed to send\n");
+		return KNOT_NET_ESEND;
+	}
+	if (gnutls_record_send(ctx->session, buf, buf_len) <= 0) {
+		WARN("TLS, failed to send\n");
+		return KNOT_NET_ESEND;
+	}
+
+	while (gnutls_record_check_corked(ctx->session) > 0) {
+		int ret = gnutls_record_uncork(ctx->session, 0);
+		if (ret < 0 && gnutls_error_is_fatal(ret) != 0) {
+			WARN("TLS, failed to send (%s)\n", gnutls_strerror(ret));
+			return KNOT_NET_ESEND;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+int tls_ctx_receive(tls_ctx_t *ctx, uint8_t *buf, const size_t buf_len)
+{
+	if (ctx == NULL || buf == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Initialize poll descriptor structure.
+	struct pollfd pfd = {
+		.fd = ctx->sockfd,
+		.events = POLLIN,
+		.revents = 0,
+	};
+
+	uint32_t total = 0;
+	uint16_t msg_len = 0;
+
+	// Receive message header.
+	while (total < sizeof(msg_len)) {
+		ssize_t ret = gnutls_record_recv(ctx->session, &msg_len + total,
+		                                 sizeof(msg_len) - total);
+		if (ret > 0) {
+			total += ret;
+		} else if (ret == 0) {
+			WARN("TLS, peer has closed the connection\n");
+			return KNOT_NET_ERECV;
+		} else if (gnutls_error_is_fatal(ret) != 0) {
+			WARN("TLS, failed to receive reply (%s)\n",
+			     gnutls_strerror(ret));
+			return KNOT_NET_ERECV;
+		} else if (poll(&pfd, 1, 1000 * ctx->wait) != 1) {
+			WARN("TLS, peer took too long to respond\n");
+			return KNOT_NET_ETIMEOUT;
+		}
+	}
+
+	// Convert number to host format.
+	msg_len = ntohs(msg_len);
+	if (msg_len > buf_len) {
+		return KNOT_ESPACE;
+	}
+
+	total = 0;
+
+	// Receive data over TLS
+	while (total < msg_len) {
+		ssize_t ret = gnutls_record_recv(ctx->session, buf + total,
+		                                 msg_len - total);
+		if (ret > 0) {
+			total += ret;
+		} else if (ret == 0) {
+			WARN("TLS, peer has closed the connection\n");
+			return KNOT_NET_ERECV;
+		} else if (gnutls_error_is_fatal(ret) != 0) {
+			WARN("TLS, failed to receive reply (%s)\n",
+			     gnutls_strerror(ret));
+			return KNOT_NET_ERECV;
+		} else if (poll(&pfd, 1, 1000 * ctx->wait) != 1) {
+			WARN("TLS, peer took too long to respond\n");
+			return KNOT_NET_ETIMEOUT;
+		}
+	}
+
+	return total;
+}
+
+void tls_ctx_close(tls_ctx_t *ctx)
+{
+	if (ctx == NULL || ctx->session == NULL) {
+		return;
+	}
+
+	gnutls_bye(ctx->session, GNUTLS_SHUT_RDWR);
+	gnutls_deinit(ctx->session);
+}
+
+void tls_ctx_deinit(tls_ctx_t *ctx)
+{
+	if (ctx == NULL) {
+		return;
+	}
+
+	if (ctx->credentials != NULL) {
+		gnutls_certificate_free_credentials(ctx->credentials);
+	}
+}
+
+void print_tls(const tls_ctx_t *ctx)
+{
+	if (ctx == NULL || ctx->session == NULL) {
+		return;
+	}
+
+	char *msg = gnutls_session_get_desc(ctx->session);
+	printf(";; TLS session %s\n", msg);
+	gnutls_free(msg);
+}