Added a DANE library.

1 files changed, 559 insertions, 0 deletions

diff --git a/libdane/dane.c b/libdane/dane.c
new file mode 100644
index 0000000000..f3d28341e3
--- /dev/null
+++ b/libdane/dane.c
@@ -0,0 +1,559 @@
+/*
+ * Copyright (C) 2012 KU Leuven
+ *
+ * Author: Nikos Mavrogiannopoulos
+ *
+ * This file is part of libdane.
+ *
+ * libdane is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <arpa/inet.h>
+#include <unbound.h>
+#include <gnutls/dane.h>
+#include <gnutls/x509.h>
+#include <gnutls/abstract.h>
+#include <gnutls/crypto.h>
+
+#define MAX_DATA_ENTRIES 4
+
+struct dane_query_st
+{
+	unsigned int data_entries;
+	dane_cert_usage_t usage[MAX_DATA_ENTRIES];
+	dane_cert_type_t  type[MAX_DATA_ENTRIES];
+	dane_match_type_t match[MAX_DATA_ENTRIES];
+	gnutls_datum_t data[MAX_DATA_ENTRIES];
+	struct ub_ctx* ctx;
+	struct ub_result* result;
+	unsigned int flags;
+	dane_query_status_t status;
+};
+
+/**
+ * dane_query_status:
+ * @q: The query structure
+ *
+ * This function will return the status of the query response.
+ * See %dane_query_status_t for the possible types.
+ *
+ * Returns: The status type.
+ **/
+dane_query_status_t dane_query_status(dane_query_t q)
+{
+	return q->status;
+}
+
+/**
+ * dane_query_entries:
+ * @q: The query structure
+ *
+ * This function will return the number of entries in a query.
+ *
+ * Returns: The number of entries.
+ **/
+unsigned int dane_query_entries(dane_query_t q)
+{
+	return q->data_entries;
+}
+
+/**
+ * dane_query_data:
+ * @q: The query structure
+ * @idx: The index of the query response.
+ * @usage: The certificate usage (see %dane_cert_usage_t)
+ * @type: The certificate type (see %dane_cert_type_t)
+ * @match: The DANE matching type (see %dane_match_type_t)
+ * @data: The DANE data.
+ *
+ * This function will provide the DANE data from the query
+ * response.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int dane_query_data(dane_query_t q, unsigned int idx,
+			unsigned int *usage, unsigned int *type,
+			unsigned int *match, gnutls_datum_t * data)
+{
+	if (idx >= q->data_entries)
+		return DANE_E_REQUESTED_DATA_NOT_AVAILABLE;
+
+	if (usage)
+		*usage = q->usage[idx];
+	if (type)
+		*type = q->type[idx];
+	if (match)
+		*match = q->match[idx];
+	if (data) {
+		data->data = q->data[idx].data;
+		data->size = q->data[idx].size;
+	}
+
+	return DANE_E_SUCCESS;
+}
+
+/**
+ * dane_query_init:
+ * @q: The structure to be initialized
+ * @flags: flags from the DANE_F_* definitions
+ *
+ * This function will initialize a DANE query structure.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int dane_query_init(dane_query_t* q, unsigned int flags)
+{
+	struct ub_ctx* ctx;
+	int ret;
+
+	*q = calloc(1, sizeof(struct dane_query_st));
+	if (*q == NULL)
+		return DANE_E_MEMORY_ERROR;
+
+	ctx = ub_ctx_create();
+	if(!ctx) {
+		ret = DANE_E_INITIALIZATION_ERROR;
+		goto cleanup;
+	}
+	ub_ctx_debugout(ctx, stderr);
+
+	if (!(flags & DANE_F_IGNORE_LOCAL_RESOLVER)) {
+		if( (ret=ub_ctx_resolvconf(ctx, NULL)) != 0) {
+			ret = DANE_E_INITIALIZATION_ERROR;
+			goto cleanup;
+		}
+
+		if( (ret=ub_ctx_hosts(ctx, NULL)) != 0) {
+			ret = DANE_E_INITIALIZATION_ERROR;
+			goto cleanup;
+		}
+	}
+
+	/* read public keys for DNSSEC verification */
+	if( (ret=ub_ctx_add_ta_file(ctx, (char*)UNBOUND_ROOT_KEY_FILE)) != 0) {
+		ret = DANE_E_INITIALIZATION_ERROR;
+		goto cleanup;
+	}
+
+	(*q)->ctx = ctx;
+	(*q)->flags = flags;
+	
+	return DANE_E_SUCCESS;
+cleanup:
+
+	if (ctx)
+		ub_ctx_delete(ctx);
+	free(*q);
+	
+	return ret;
+}
+
+/**
+ * dane_query_init:
+ * @q: The structure to be deinitialized
+ *
+ * This function will deinitialize a DANE query structure.
+ *
+ **/
+void dane_query_deinit(dane_query_t q)
+{
+	if (q->result)
+	ub_ctx_delete(q->ctx);
+		ub_resolve_free(q->result);
+
+	free(q);
+}
+
+/**
+ * dane_query_resolve_tlsa:
+ * @q: The query structure
+ * @host: The host name to resolve.
+ * @proto: The protocol type (tcp, udp, etc.)
+ * @port: The service port number (eg. 443).
+ *
+ * This function will query the DNS server for the TLSA (DANE)
+ * data for the given host.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int dane_query_resolve_tlsa(dane_query_t q, const char* host, const char* proto, unsigned int port)
+{
+	char ns[1024];
+	int ret;
+	unsigned int i;
+
+	if (q->result) {
+		ub_resolve_free(q->result);
+		q->result = NULL;
+	}
+	
+	snprintf(ns, sizeof(ns), "_%u._%s.%s", port, proto, host);
+
+	/* query for webserver */
+	ret = ub_resolve(q->ctx, ns, 52, 1, &q->result);
+	if(ret != 0) {
+		return DANE_E_RESOLVING_ERROR;
+	}
+
+/* show first result */
+	if(!q->result->havedata) {
+		return DANE_E_NO_DANE_DATA;
+	}
+
+	i = 0;
+	do {
+
+		if (q->result->len[i] > 3)
+			ret = DANE_E_SUCCESS;
+		else {
+			return DANE_E_RECEIVED_CORRUPT_DATA;
+		}
+	
+		q->usage[i] = q->result->data[i][0];
+		q->type[i] = q->result->data[i][1];
+		q->match[i] = q->result->data[i][2];
+		q->data[i].data = (void*)&q->result->data[i][3];
+		q->data[i].size = q->result->len[i];
+		i++;
+	} while(q->result->data[i] != NULL);
+	
+	q->data_entries = i;
+
+	if (q->flags & DANE_F_REQUIRE_DNSSEC) {
+		if (!q->result->secure) {
+			if (q->result->bogus)
+				ret = DANE_E_INVALID_DNSSEC_SIG;
+			else
+				ret = DANE_E_NO_DNSSEC_SIG;
+		}
+	}
+
+	/* show security status */
+	if (q->result->secure)
+		q->status = DANE_QUERY_DNSSEC_VERIFIED;
+	else if (q->result->bogus)
+		q->status = DANE_QUERY_BOGUS;
+	else q->status = DANE_QUERY_NO_DNSSEC;
+
+	return ret;
+}
+
+static unsigned int matches(const gnutls_datum_t *raw1, const gnutls_datum_t *raw2, 
+							dane_match_type_t match)
+{
+uint8_t digest[64];
+int ret;
+
+	if (match == DANE_MATCH_EXACT) {
+		if (raw1->size != raw2->size)
+			return 0;
+
+		if (memcmp(raw1->data, raw2->data, raw1->size) != 0)
+			return 0;
+		
+		return 1;
+	} else if (match == DANE_MATCH_SHA2_256) {
+
+		if (raw2->size < 32)
+			return 0;
+		
+		ret = gnutls_hash_fast(GNUTLS_DIG_SHA256, raw1->data, raw1->size, digest);
+		if (ret < 0)
+			return 0;
+
+		if (memcmp(digest, raw2->data, 32) != 0)
+			return 0;
+		
+		return 1;
+	} else if (match == DANE_MATCH_SHA2_512) {
+		if (raw2->size < 64)
+			return 0;
+		
+		ret = gnutls_hash_fast(GNUTLS_DIG_SHA512, raw1->data, raw1->size, digest);
+		if (ret < 0)
+			return 0;
+		
+		if (memcmp(digest, raw2->data, 64) != 0)
+			return 0;
+		
+		return 1;
+	}
+	
+	return 0;
+}
+
+static int crt_to_pubkey(const gnutls_datum_t *raw_crt, gnutls_datum_t * out)
+{
+gnutls_pubkey_t pub = NULL;
+gnutls_x509_crt_t crt = NULL;
+int ret;
+size_t size;
+
+	out->data = NULL;
+
+	ret = gnutls_x509_crt_init(&crt);
+	if (ret < 0)
+		return DANE_E_PUBKEY_ERROR;
+
+	ret = gnutls_pubkey_init( &pub);
+	if (ret < 0) {
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+		
+	ret = gnutls_x509_crt_import(crt, raw_crt, GNUTLS_X509_FMT_DER);
+	if (ret < 0) {
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	ret = gnutls_pubkey_import_x509(pub, crt, 0);
+	if (ret < 0) {
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	size = 0;
+	ret = gnutls_pubkey_export(pub, GNUTLS_X509_FMT_DER, NULL, &size);
+	if (ret < 0 && ret != GNUTLS_E_SHORT_MEMORY_BUFFER) {
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+	
+	out->data = malloc(size);
+	if (out->data == NULL) {
+		ret = DANE_E_MEMORY_ERROR;
+		goto cleanup;
+	}
+
+	ret = gnutls_pubkey_export(pub, GNUTLS_X509_FMT_DER, out->data, &size);
+	if (ret < 0) {
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+	
+	out->size = size;
+
+	ret = 0;
+	goto clean_certs;
+
+cleanup:
+	free(out->data);
+clean_certs:
+	if (pub)
+		gnutls_pubkey_deinit(pub);
+	if (crt)
+		gnutls_x509_crt_deinit(crt);
+
+	return ret;
+}
+
+static int verify_ca(const gnutls_datum_t *raw_crt, unsigned raw_crt_size,
+					 gnutls_certificate_type_t crt_type,
+					 dane_cert_type_t ctype,
+					 dane_match_type_t match, gnutls_datum_t * data,
+					 unsigned int *verify)
+{
+gnutls_datum_t pubkey = {NULL, 0};
+int ret;
+
+	if (raw_crt_size < 2)
+		return DANE_E_INVALID_REQUEST;
+
+	if (ctype == DANE_CERT_X509 && crt_type == GNUTLS_CRT_X509) {
+	
+		if (!matches(&raw_crt[1], data, match))
+			*verify |= DANE_VERIFY_CA_CONSTRAINS_VIOLATED;
+
+	} else if (ctype == DANE_CERT_PK && crt_type == GNUTLS_CRT_X509) {
+		ret = crt_to_pubkey(&raw_crt[1], &pubkey);
+		if (ret < 0)
+			goto cleanup;
+
+		if (!matches(&pubkey, data, match))
+			*verify |= DANE_VERIFY_CA_CONSTRAINS_VIOLATED;
+	}
+
+	ret = 0;
+cleanup:
+	free(pubkey.data);
+	return ret;
+}
+
+static int verify_ee(const gnutls_datum_t *raw_crt, gnutls_certificate_type_t crt_type,
+		 dane_cert_type_t ctype, dane_match_type_t match, gnutls_datum_t * data,
+		 unsigned int *verify)
+{
+gnutls_datum_t pubkey = {NULL, 0};
+int ret;
+
+	if (ctype == DANE_CERT_X509 && crt_type == GNUTLS_CRT_X509) {
+
+		if (!matches(raw_crt, data, match))
+			*verify |= DANE_VERIFY_CERT_DIFFERS;
+
+	} else if (ctype == DANE_CERT_PK && crt_type == GNUTLS_CRT_X509) {
+
+		ret = crt_to_pubkey(raw_crt, &pubkey);
+		if (ret < 0)
+			goto cleanup;
+
+		if (!matches(&pubkey, data, match))
+			*verify |= DANE_VERIFY_CERT_DIFFERS;
+	}
+
+	ret = 0;
+cleanup:
+	free(pubkey.data);
+	return ret;
+}
+
+/**
+ * dane_verify_crt:
+ * @chain: A certificate chain
+ * @chain_size: The size of the chain
+ * @chain_type: The type of the certificate chain
+ * @hostname: The hostname associated with the chain
+ * @proto: The protocol of the service connecting (e.g. tcp)
+ * @port: The port of the service connecting (e.g. 443)
+ * @flags: The %DANE_F flags.
+ * @verify: An OR'ed list of %dane_verify_status_t.
+ *
+ * This function will verify the given certificate chain against the
+ * CA constrains and/or the certificate available via DANE. 
+ * If no information via DANE can be obtained the flag %DANE_VERIFY_NO_DANE_INFO
+ * is set. If a DNSSEC signature is not available for the DANE 
+ * record then the verify flag %DANE_VERIFY_NO_DNSSEC_DATA is set.
+ * 
+ * Note that when verifying untrusted certificates, it is recommended to 
+ * use the %DANE_F_REQUIRE_DNSSEC flag.
+ * 
+ * Due to the many possible options of DANE, there is no single threat
+ * model countered. When notifying the user about DANE verification results
+ * it may be better to mention: DANE verification did not reject the certificate,
+ * rather than mentioning a successful DANE verication.
+ * 
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ *
+ **/
+int dane_verify_crt (
+	const gnutls_datum_t *chain, unsigned chain_size,
+	gnutls_certificate_type_t chain_type,
+	const char * hostname, const char* proto, unsigned int port,
+	unsigned int flags, unsigned int *verify)
+{
+dane_query_t q;
+int ret;
+unsigned int usage, type, match, idx, status;
+gnutls_datum_t data;
+	
+	if (chain_type != GNUTLS_CRT_X509)
+		return DANE_E_INVALID_REQUEST;
+	
+	*verify = 0;
+	
+	ret = dane_query_init(&q, flags);
+	if (ret < 0) {
+		return ret;
+	}
+	
+	ret = dane_query_resolve_tlsa(q, hostname, proto, port);
+	if (ret < 0) {
+		goto cleanup;
+	}
+
+	status = dane_query_status(q);
+	if (status == DANE_QUERY_BOGUS) {
+		*verify |= DANE_VERIFY_DNSSEC_DATA_INVALID;
+		goto cleanup;
+	} else if (status == DANE_QUERY_NO_DNSSEC) {
+		*verify |= DANE_VERIFY_NO_DNSSEC_DATA;
+		goto cleanup;
+	}
+
+	idx = 0;
+	do {
+		ret = dane_query_data(q, idx++, &usage, &type, &match, &data);
+		if (ret == DANE_E_REQUESTED_DATA_NOT_AVAILABLE)
+			break;
+
+		if (ret < 0) {
+			goto cleanup;
+		}
+	
+		if (usage == DANE_CERT_USAGE_LOCAL_CA || usage == DANE_CERT_USAGE_CA) {
+			ret = verify_ca(chain, chain_size, chain_type, type, match, &data, verify);
+			if (ret < 0)
+				goto cleanup;
+		
+		} else if (usage == DANE_CERT_USAGE_LOCAL_EE || usage == DANE_CERT_USAGE_EE) {
+			ret = verify_ee(&chain[0], chain_type, type, match, &data, verify);
+			if (ret < 0)
+				goto cleanup;
+		}
+	} while(1);
+
+	ret = 0;
+
+cleanup:
+	dane_query_deinit(q);
+	return ret;
+}
+
+/**
+ * dane_verify_session_crt:
+ * @session: A gnutls session
+ * @hostname: The hostname associated with the chain
+ * @proto: The protocol of the service connecting (e.g. tcp)
+ * @port: The port of the service connecting (e.g. 443)
+ * @flags: The %DANE_F flags.
+ * @verify: An OR'ed list of %dane_verify_status_t.
+ *
+ * This function will verify session's certificate chain against the
+ * CA constrains and/or the certificate available via DANE. 
+ * See dane_verify_crt() for more information.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ *
+ **/
+int dane_verify_session_crt (
+	gnutls_session_t session,
+	const char * hostname, const char* proto, unsigned int port,
+	unsigned int flags, unsigned int *verify)
+{
+const gnutls_datum_t *cert_list;
+unsigned int cert_list_size = 0;
+unsigned int type;
+
+	cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
+	if (cert_list_size == 0) {
+		return DANE_E_NO_CERT;
+	}
+	
+	type = gnutls_certificate_type_get(session);
+	
+	return dane_verify_crt(cert_list, cert_list_size, type, hostname, proto, port, flags, verify);
+}