Implemented a generic TLS EAP helper to implement EAP-TLS, TTLS and other variants

3 files changed, 415 insertions, 0 deletions

diff --git a/src/libtls/Makefile.am b/src/libtls/Makefile.am
index 66819f2a2..a58e783d7 100644
--- a/src/libtls/Makefile.am
+++ b/src/libtls/Makefile.am
@@ -12,6 +12,7 @@ libtls_la_SOURCES = \
 	tls_reader.h tls_reader.c \
 	tls_writer.h tls_writer.c \
 	tls_socket.h tls_socket.c \
+	tls_eap.h tls_eap.c \
 	tls_peer.h tls_peer.c \
 	tls_server.h tls_server.c \
 	tls_handshake.h tls_application.h tls.h tls.c
diff --git a/src/libtls/tls_eap.c b/src/libtls/tls_eap.c
new file mode 100644
index 000000000..027929806
--- /dev/null
+++ b/src/libtls/tls_eap.c
@@ -0,0 +1,331 @@
+/*
+ * Copyright (C) 2010 Martin Willi
+ * Copyright (C) 2010 revosec AG
+ *
+ * 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 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+#include "tls_eap.h"
+
+#include "tls.h"
+
+#include <debug.h>
+#include <library.h>
+
+/** Size limit for a single TLS message */
+#define MAX_TLS_MESSAGE_LEN 65536
+/** Size of a EAP-TLS fragment */
+#define EAP_TLS_FRAGMENT_LEN 1014
+
+typedef struct private_tls_eap_t private_tls_eap_t;
+
+/**
+ * Private data of an tls_eap_t object.
+ */
+struct private_tls_eap_t {
+
+	/**
+	 * Public tls_eap_t interface.
+	 */
+	tls_eap_t public;
+
+	/**
+	 * Type of EAP method, EAP-TLS or EAP-TTLS
+	 */
+	eap_type_t type;
+
+	/**
+	 * TLS stack
+	 */
+	tls_t *tls;
+
+	/**
+	 * Role
+	 */
+	bool is_server;
+
+	/**
+	 * First fragment of a multi-fragment record?
+	 */
+	bool first_fragment;
+};
+
+/**
+ * Flags of an EAP-TLS/TTLS message
+ */
+typedef enum {
+	EAP_TLS_LENGTH = (1<<7),
+	EAP_TLS_MORE_FRAGS = (1<<6),
+	EAP_TLS_START = (1<<5),
+	EAP_TTLS_VERSION = (0x07),
+} eap_tls_flags_t;
+
+/**
+ * EAP-TLS/TTLS packet format
+ */
+typedef struct __attribute__((packed)) {
+	u_int8_t code;
+	u_int8_t identifier;
+	u_int16_t length;
+	u_int8_t type;
+	u_int8_t flags;
+} eap_tls_packet_t;
+
+METHOD(tls_eap_t, initiate, status_t,
+	private_tls_eap_t *this, chunk_t *out)
+{
+	if (this->is_server)
+	{
+		eap_tls_packet_t pkt = {
+			.type = this->type,
+			.code = EAP_REQUEST,
+			.flags = EAP_TLS_START,
+		};
+		htoun16(&pkt.length, sizeof(eap_tls_packet_t));
+		do
+		{	/* start with non-zero random identifier */
+			pkt.identifier = random();
+		}
+		while (!pkt.identifier);
+
+		DBG2(DBG_IKE, "sending %N start packet", eap_type_names, this->type);
+		*out = chunk_clone(chunk_from_thing(pkt));
+		return NEED_MORE;
+	}
+	return FAILED;
+}
+
+/**
+ * Process a received packet
+ */
+static status_t process_pkt(private_tls_eap_t *this, eap_tls_packet_t *pkt)
+{
+	u_int32_t msg_len;
+	u_int16_t pkt_len;
+
+	pkt_len = untoh16(&pkt->length);
+	if (pkt->flags & EAP_TLS_LENGTH)
+	{
+		if (pkt_len < sizeof(eap_tls_packet_t) + sizeof(msg_len))
+		{
+			DBG1(DBG_TLS, "%N packet too short", eap_type_names, this->type);
+			return FAILED;
+		}
+		msg_len = untoh32(pkt + 1);
+		if (msg_len < pkt_len - sizeof(eap_tls_packet_t) - sizeof(msg_len) ||
+			msg_len > MAX_TLS_MESSAGE_LEN)
+		{
+			DBG1(DBG_TLS, "invalid %N packet length", eap_type_names, this->type);
+			return FAILED;
+		}
+		return this->tls->process(this->tls, (char*)(pkt + 1) + sizeof(msg_len),
+						pkt_len - sizeof(eap_tls_packet_t) - sizeof(msg_len));
+	}
+	return this->tls->process(this->tls, (char*)(pkt + 1),
+							  pkt_len - sizeof(eap_tls_packet_t));
+}
+
+/**
+ * Build a packet to send
+ */
+static status_t build_pkt(private_tls_eap_t *this,
+						  u_int8_t identifier, chunk_t *out)
+{
+	char buf[EAP_TLS_FRAGMENT_LEN];
+	eap_tls_packet_t *pkt;
+	size_t len, reclen;
+	status_t status;
+	char *kind;
+
+	pkt = (eap_tls_packet_t*)buf;
+	pkt->code = this->is_server ? EAP_REQUEST : EAP_RESPONSE;
+	pkt->identifier = this->is_server ? identifier + 1 : identifier;
+	pkt->type = this->type;
+	pkt->flags = 0;
+
+	if (this->first_fragment)
+	{
+		pkt->flags = EAP_TLS_LENGTH;
+		len = sizeof(buf) - sizeof(eap_tls_packet_t) - sizeof(u_int32_t);
+		status = this->tls->build(this->tls, buf + sizeof(eap_tls_packet_t) +
+								  sizeof(u_int32_t), &len, &reclen);
+	}
+	else
+	{
+		len = sizeof(buf) - sizeof(eap_tls_packet_t);
+		status = this->tls->build(this->tls, buf + sizeof(eap_tls_packet_t),
+								  &len, &reclen);
+	}
+	switch (status)
+	{
+		case NEED_MORE:
+			pkt->flags |= EAP_TLS_MORE_FRAGS;
+			kind = "non-first fragment";
+			if (this->first_fragment)
+			{
+				this->first_fragment = FALSE;
+				kind = "first fragment";
+			}
+			break;
+		case ALREADY_DONE:
+			kind = "packet";
+			if (!this->first_fragment)
+			{
+				this->first_fragment = TRUE;
+				kind = "final fragment";
+			}
+			break;
+		default:
+			return status;
+	}
+	DBG2(DBG_TLS, "sending %N %s (%u bytes)",
+		 eap_type_names, this->type, kind, len);
+	if (reclen)
+	{
+		htoun32(pkt + 1, reclen);
+		len += sizeof(u_int32_t);
+		pkt->flags |= EAP_TLS_LENGTH;
+	}
+	len += sizeof(eap_tls_packet_t);
+	htoun16(&pkt->length, len);
+	*out = chunk_clone(chunk_create(buf, len));
+	return NEED_MORE;
+}
+
+/**
+ * Send an ack to request next fragment
+ */
+static chunk_t create_ack(private_tls_eap_t *this, u_int8_t identifier)
+{
+	eap_tls_packet_t pkt = {
+		.code = this->is_server ? EAP_REQUEST : EAP_RESPONSE,
+		.identifier = this->is_server ? identifier + 1 : identifier,
+		.type = this->type,
+	};
+	htoun16(&pkt.length, sizeof(pkt));
+	DBG2(DBG_TLS, "sending %N acknowledgement packet",
+		 eap_type_names, this->type);
+	return chunk_clone(chunk_from_thing(pkt));
+}
+
+METHOD(tls_eap_t, process, status_t,
+	private_tls_eap_t *this, chunk_t in, chunk_t *out)
+{
+	eap_tls_packet_t *pkt;
+	status_t status;
+
+	pkt = (eap_tls_packet_t*)in.ptr;
+	if (in.len < sizeof(eap_tls_packet_t) ||
+		untoh16(&pkt->length) != in.len)
+	{
+		DBG1(DBG_IKE, "invalid EAP-TLS packet length");
+		return FAILED;
+	}
+	if (pkt->flags & EAP_TLS_START)
+	{
+		if (this->type == EAP_TTLS)
+		{
+			DBG1(DBG_TLS, "EAP-TTLS version is v%u",
+				 pkt->flags & EAP_TTLS_VERSION);
+		}
+	}
+	else
+	{
+		if (in.len == sizeof(eap_tls_packet_t))
+		{
+			DBG2(DBG_TLS, "received %N acknowledgement packet",
+				 eap_type_names, this->type);
+			status = build_pkt(this, pkt->identifier, out);
+			if (status == INVALID_STATE &&
+				this->tls->is_complete(this->tls))
+			{
+				return SUCCESS;
+			}
+			return status;
+		}
+		status = process_pkt(this, pkt);
+		if (status != NEED_MORE)
+		{
+			return status;
+		}
+	}
+	status = build_pkt(this, pkt->identifier, out);
+	switch (status)
+	{
+		case INVALID_STATE:
+			*out = create_ack(this, pkt->identifier);
+			return NEED_MORE;
+		case FAILED:
+			if (!this->is_server)
+			{
+				*out = create_ack(this, pkt->identifier);
+				return NEED_MORE;
+			}
+			return FAILED;
+		default:
+			return status;
+	}
+}
+
+METHOD(tls_eap_t, get_msk, chunk_t,
+	private_tls_eap_t *this)
+{
+	return this->tls->get_eap_msk(this->tls);
+}
+
+METHOD(tls_eap_t, destroy, void,
+	private_tls_eap_t *this)
+{
+	this->tls->destroy(this->tls);
+	free(this);
+}
+
+/**
+ * See header
+ */
+tls_eap_t *tls_eap_create(eap_type_t type, bool is_server,
+						  identification_t *server, identification_t *peer,
+						  tls_application_t *application)
+{
+	private_tls_eap_t *this;
+	tls_purpose_t purpose;
+
+	switch (type)
+	{
+		case EAP_TLS:
+			purpose = TLS_PURPOSE_EAP_TLS;
+			break;
+		case EAP_TTLS:
+			purpose = TLS_PURPOSE_EAP_TTLS;
+			break;
+		default:
+			return NULL;
+	};
+
+	INIT(this,
+		.public = {
+			.initiate = _initiate,
+			.process = _process,
+			.get_msk = _get_msk,
+			.destroy = _destroy,
+		},
+		.type = type,
+		.is_server = is_server,
+		.first_fragment = TRUE,
+		.tls = tls_create(is_server, server, peer, purpose, application),
+	);
+	if (!this->tls)
+	{
+		free(this);
+		return NULL;
+	}
+	return &this->public;
+}
diff --git a/src/libtls/tls_eap.h b/src/libtls/tls_eap.h
new file mode 100644
index 000000000..48b4dec62
--- /dev/null
+++ b/src/libtls/tls_eap.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2010 Martin Willi
+ * Copyright (C) 2010 revosec AG
+ *
+ * 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 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup tls_eap tls_eap
+ * @{ @ingroup libtls
+ */
+
+#ifndef TLS_EAP_H_
+#define TLS_EAP_H_
+
+typedef struct tls_eap_t tls_eap_t;
+
+#include <eap/eap.h>
+
+#include "tls_application.h"
+
+/**
+ * TLS over EAP helper, as used by EAP-TLS and EAP-TTLS.
+ */
+struct tls_eap_t {
+
+	/**
+	 * Initiate TLS over EAP exchange (as client).
+	 *
+	 * @param out			allocated EAP packet data to send
+	 * @return
+	 *						- NEED_MORE if more exchanges required
+	 *						- FAILED if initiation failed
+	 */
+	status_t (*initiate)(tls_eap_t *this, chunk_t *out);
+
+	/**
+	 * Process a received EAP-TLS/TTLS packet, create response.
+	 *
+	 * @param in			EAP packet data to process
+	 * @param out			allocated EAP packet data to send
+	 * @return
+	 *						- SUCCESS if TLS negotiation completed
+	 *						- FAILED if TLS negotiation failed
+	 *						- NEED_MORE if more exchanges required
+	 */
+	status_t (*process)(tls_eap_t *this, chunk_t in, chunk_t *out);
+
+	/**
+	 * Get the EAP-MSK.
+	 *
+	 * @return				MSK
+	 */
+	chunk_t (*get_msk)(tls_eap_t *this);
+
+	/**
+	 * Destroy a tls_eap_t.
+	 */
+	void (*destroy)(tls_eap_t *this);
+};
+
+/**
+ * Create a tls_eap instance.
+ *
+ * @param type				EAP type, EAP-TLS or EAP-TTLS
+ * @param is_server			role
+ * @param server			server identity
+ * @param peer				peer identity, NULL to omit peer authentication
+ * @param application		TLS application layer, if any
+ */
+tls_eap_t *tls_eap_create(eap_type_t type, bool is_server,
+						  identification_t *server, identification_t *peer,
+						  tls_application_t *application);
+
+#endif /** TLS_EAP_H_ @}*/