1 files changed, 490 insertions, 0 deletions

diff --git a/src/libcharon/sa/tasks/ike_natd.c b/src/libcharon/sa/tasks/ike_natd.c
new file mode 100644
index 000000000..9ea20ba36
--- /dev/null
+++ b/src/libcharon/sa/tasks/ike_natd.c
@@ -0,0 +1,490 @@
+/*
+ * Copyright (C) 2006-2007 Martin Willi
+ * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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 "ike_natd.h"
+
+#include <string.h>
+
+#include <daemon.h>
+#include <config/peer_cfg.h>
+#include <crypto/hashers/hasher.h>
+#include <encoding/payloads/notify_payload.h>
+
+
+typedef struct private_ike_natd_t private_ike_natd_t;
+
+/**
+ * Private members of a ike_natd_t task.
+ */
+struct private_ike_natd_t {
+
+	/**
+	 * Public methods and task_t interface.
+	 */
+	ike_natd_t public;
+
+	/**
+	 * Assigned IKE_SA.
+	 */
+	ike_sa_t *ike_sa;
+
+	/**
+	 * Are we the initiator?
+	 */
+	bool initiator;
+
+	/**
+	 * Hasher used to build NAT detection hashes
+	 */
+	hasher_t *hasher;
+
+	/**
+	 * Did we process any NAT detection notifys for a source address?
+	 */
+	bool src_seen;
+
+	/**
+	 * Did we process any NAT detection notifys for a destination address?
+	 */
+	bool dst_seen;
+
+	/**
+	 * Have we found a matching source address NAT hash?
+	 */
+	bool src_matched;
+
+	/**
+	 * Have we found a matching destination address NAT hash?
+	 */
+	bool dst_matched;
+
+	/**
+	 * whether NAT mappings for our NATed address has changed
+	 */
+	bool mapping_changed;
+};
+
+
+/**
+ * Build NAT detection hash for a host
+ */
+static chunk_t generate_natd_hash(private_ike_natd_t *this,
+								  ike_sa_id_t *ike_sa_id, host_t *host)
+{
+	chunk_t natd_chunk, spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk;
+	chunk_t natd_hash;
+	u_int64_t spi_i, spi_r;
+	u_int16_t port;
+
+	/* prepare all required chunks */
+	spi_i = ike_sa_id->get_initiator_spi(ike_sa_id);
+	spi_r = ike_sa_id->get_responder_spi(ike_sa_id);
+	spi_i_chunk.ptr = (void*)&spi_i;
+	spi_i_chunk.len = sizeof(spi_i);
+	spi_r_chunk.ptr = (void*)&spi_r;
+	spi_r_chunk.len = sizeof(spi_r);
+	port = htons(host->get_port(host));
+	port_chunk.ptr = (void*)&port;
+	port_chunk.len = sizeof(port);
+	addr_chunk = host->get_address(host);
+
+	/*  natd_hash = SHA1( spi_i | spi_r | address | port ) */
+	natd_chunk = chunk_cat("cccc", spi_i_chunk, spi_r_chunk, addr_chunk, port_chunk);
+	this->hasher->allocate_hash(this->hasher, natd_chunk, &natd_hash);
+	DBG3(DBG_IKE, "natd_chunk %B", &natd_chunk);
+	DBG3(DBG_IKE, "natd_hash %B", &natd_hash);
+
+	chunk_free(&natd_chunk);
+	return natd_hash;
+}
+
+/**
+ * build a faked NATD payload to enforce UDP encap
+ */
+static chunk_t generate_natd_hash_faked(private_ike_natd_t *this)
+{
+	rng_t *rng;
+	chunk_t chunk;
+
+	rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
+	if (!rng)
+	{
+		DBG1(DBG_IKE, "unable to get random bytes for NATD fake");
+		return chunk_empty;
+	}
+	rng->allocate_bytes(rng, HASH_SIZE_SHA1, &chunk);
+	rng->destroy(rng);
+	return chunk;
+}
+
+/**
+ * Build a NAT detection notify payload.
+ */
+static notify_payload_t *build_natd_payload(private_ike_natd_t *this,
+											notify_type_t type, host_t *host)
+{
+	chunk_t hash;
+	notify_payload_t *notify;
+	ike_sa_id_t *ike_sa_id;
+	ike_cfg_t *config;
+
+	ike_sa_id = this->ike_sa->get_id(this->ike_sa);
+	config = this->ike_sa->get_ike_cfg(this->ike_sa);
+	if (config->force_encap(config) && type == NAT_DETECTION_SOURCE_IP)
+	{
+		hash = generate_natd_hash_faked(this);
+	}
+	else
+	{
+		hash = generate_natd_hash(this, ike_sa_id, host);
+	}
+	notify = notify_payload_create();
+	notify->set_notify_type(notify, type);
+	notify->set_notification_data(notify, hash);
+	chunk_free(&hash);
+
+	return notify;
+}
+
+/**
+ * read notifys from message and evaluate them
+ */
+static void process_payloads(private_ike_natd_t *this, message_t *message)
+{
+	enumerator_t *enumerator;
+	payload_t *payload;
+	notify_payload_t *notify;
+	chunk_t hash, src_hash, dst_hash;
+	ike_sa_id_t *ike_sa_id;
+	host_t *me, *other;
+	ike_cfg_t *config;
+
+	/* Precompute NAT-D hashes for incoming NAT notify comparison */
+	ike_sa_id = message->get_ike_sa_id(message);
+	me = message->get_destination(message);
+	other = message->get_source(message);
+	dst_hash = generate_natd_hash(this, ike_sa_id, me);
+	src_hash = generate_natd_hash(this, ike_sa_id, other);
+
+	DBG3(DBG_IKE, "precalculated src_hash %B", &src_hash);
+	DBG3(DBG_IKE, "precalculated dst_hash %B", &dst_hash);
+
+	enumerator = message->create_payload_enumerator(message);
+	while (enumerator->enumerate(enumerator, &payload))
+	{
+		if (payload->get_type(payload) != NOTIFY)
+		{
+			continue;
+		}
+		notify = (notify_payload_t*)payload;
+		switch (notify->get_notify_type(notify))
+		{
+			case NAT_DETECTION_DESTINATION_IP:
+			{
+				this->dst_seen = TRUE;
+				hash = notify->get_notification_data(notify);
+				if (!this->dst_matched)
+				{
+					DBG3(DBG_IKE, "received dst_hash %B", &hash);
+					if (chunk_equals(hash, dst_hash))
+					{
+						this->dst_matched = TRUE;
+					}
+				}
+				/* RFC4555 says we should also compare against IKE_SA_INIT
+				 * NATD payloads, but this does not work: We are running
+				 * there at port 500, but use 4500 afterwards... */
+				if (message->get_exchange_type(message) == INFORMATIONAL &&
+					this->initiator && !this->dst_matched)
+				{
+					this->mapping_changed = this->ike_sa->has_mapping_changed(
+															this->ike_sa, hash);
+				}
+				break;
+			}
+			case NAT_DETECTION_SOURCE_IP:
+			{
+				this->src_seen = TRUE;
+				if (!this->src_matched)
+				{
+					hash = notify->get_notification_data(notify);
+					DBG3(DBG_IKE, "received src_hash %B", &hash);
+					if (chunk_equals(hash, src_hash))
+					{
+						this->src_matched = TRUE;
+					}
+				}
+				break;
+			}
+			default:
+				break;
+		}
+	}
+	enumerator->destroy(enumerator);
+
+	chunk_free(&src_hash);
+	chunk_free(&dst_hash);
+
+	if (this->src_seen && this->dst_seen)
+	{
+		this->ike_sa->enable_extension(this->ike_sa, EXT_NATT);
+
+		this->ike_sa->set_condition(this->ike_sa, COND_NAT_HERE,
+									!this->dst_matched);
+		this->ike_sa->set_condition(this->ike_sa, COND_NAT_THERE,
+									!this->src_matched);
+		config = this->ike_sa->get_ike_cfg(this->ike_sa);
+		if (this->dst_matched && this->src_matched &&
+			config->force_encap(config))
+		{
+			this->ike_sa->set_condition(this->ike_sa, COND_NAT_FAKE, TRUE);
+		}
+	}
+}
+
+/**
+ * Implementation of task_t.process for initiator
+ */
+static status_t process_i(private_ike_natd_t *this, message_t *message)
+{
+	process_payloads(this, message);
+
+	if (message->get_exchange_type(message) == IKE_SA_INIT)
+	{
+		peer_cfg_t *peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
+
+#ifdef ME
+		/* if we are on a mediated connection we have already switched to
+		 * port 4500 and the correct destination port is already configured,
+		 * therefore we must not switch again */
+		if (peer_cfg->get_mediated_by(peer_cfg))
+		{
+			return SUCCESS;
+		}
+#endif /* ME */
+
+		if (this->ike_sa->has_condition(this->ike_sa, COND_NAT_ANY) ||
+#ifdef ME
+			/* if we are on a mediation connection we switch to port 4500 even
+			 * if no NAT is detected. */
+			peer_cfg->is_mediation(peer_cfg) ||
+#endif /* ME */
+			/* if peer supports NAT-T, we switch to port 4500 even
+			 * if no NAT is detected. MOBIKE requires this. */
+			(peer_cfg->use_mobike(peer_cfg) &&
+			 this->ike_sa->supports_extension(this->ike_sa, EXT_NATT)))
+		{
+			host_t *me, *other;
+
+			/* do not switch if we have a custom port from mobike/NAT */
+			me = this->ike_sa->get_my_host(this->ike_sa);
+			if (me->get_port(me) == IKEV2_UDP_PORT)
+			{
+				me->set_port(me, IKEV2_NATT_PORT);
+			}
+			other = this->ike_sa->get_other_host(this->ike_sa);
+			if (other->get_port(other) == IKEV2_UDP_PORT)
+			{
+				other->set_port(other, IKEV2_NATT_PORT);
+			}
+		}
+	}
+
+	return SUCCESS;
+}
+
+/**
+ * Implementation of task_t.process for initiator
+ */
+static status_t build_i(private_ike_natd_t *this, message_t *message)
+{
+	notify_payload_t *notify;
+	enumerator_t *enumerator;
+	ike_cfg_t *ike_cfg;
+	host_t *host;
+
+	if (this->hasher == NULL)
+	{
+		DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
+		return NEED_MORE;
+	}
+
+	ike_cfg = this->ike_sa->get_ike_cfg(this->ike_sa);
+
+	/* destination is always set */
+	host = message->get_destination(message);
+	notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, host);
+	message->add_payload(message, (payload_t*)notify);
+
+	/* source may be any, we have 3 possibilities to get our source address:
+	 * 1. It is defined in the config => use the one of the IKE_SA
+	 * 2. We do a routing lookup in the kernel interface
+	 * 3. Include all possbile addresses
+	 */
+	host = message->get_source(message);
+	if (!host->is_anyaddr(host))
+	{	/* 1. */
+		notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+		message->add_payload(message, (payload_t*)notify);
+	}
+	else
+	{
+		host = charon->kernel_interface->get_source_addr(charon->kernel_interface,
+							this->ike_sa->get_other_host(this->ike_sa), NULL);
+		if (host)
+		{	/* 2. */
+			host->set_port(host, ike_cfg->get_my_port(ike_cfg));
+			notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+			message->add_payload(message, (payload_t*)notify);
+			host->destroy(host);
+		}
+		else
+		{	/* 3. */
+			enumerator = charon->kernel_interface->create_address_enumerator(
+										charon->kernel_interface, FALSE, FALSE);
+			while (enumerator->enumerate(enumerator, (void**)&host))
+			{
+				/* apply port 500 to host, but work on a copy */
+				host = host->clone(host);
+				host->set_port(host, ike_cfg->get_my_port(ike_cfg));
+				notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, host);
+				host->destroy(host);
+				message->add_payload(message, (payload_t*)notify);
+			}
+			enumerator->destroy(enumerator);
+		}
+	}
+	return NEED_MORE;
+}
+
+/**
+ * Implementation of task_t.build for responder
+ */
+static status_t build_r(private_ike_natd_t *this, message_t *message)
+{
+	notify_payload_t *notify;
+	host_t *me, *other;
+
+	/* only add notifies on successfull responses. */
+	if (message->get_exchange_type(message) == IKE_SA_INIT &&
+		message->get_payload(message, SECURITY_ASSOCIATION) == NULL)
+	{
+		return SUCCESS;
+	}
+
+	if (this->src_seen && this->dst_seen)
+	{
+		if (this->hasher == NULL)
+		{
+			DBG1(DBG_IKE, "unable to build NATD payloads, SHA1 not supported");
+			return SUCCESS;
+		}
+
+		/* initiator seems to support NAT detection, add response */
+		me = message->get_source(message);
+		notify = build_natd_payload(this, NAT_DETECTION_SOURCE_IP, me);
+		message->add_payload(message, (payload_t*)notify);
+
+		other = message->get_destination(message);
+		notify = build_natd_payload(this, NAT_DETECTION_DESTINATION_IP, other);
+		message->add_payload(message, (payload_t*)notify);
+	}
+	return SUCCESS;
+}
+
+/**
+ * Implementation of task_t.process for responder
+ */
+static status_t process_r(private_ike_natd_t *this, message_t *message)
+{
+	process_payloads(this, message);
+
+	return NEED_MORE;
+}
+
+/**
+ * Implementation of task_t.get_type
+ */
+static task_type_t get_type(private_ike_natd_t *this)
+{
+	return IKE_NATD;
+}
+
+/**
+ * Implementation of task_t.migrate
+ */
+static void migrate(private_ike_natd_t *this, ike_sa_t *ike_sa)
+{
+	this->ike_sa = ike_sa;
+	this->src_seen = FALSE;
+	this->dst_seen = FALSE;
+	this->src_matched = FALSE;
+	this->dst_matched = FALSE;
+	this->mapping_changed = FALSE;
+}
+
+/**
+ * Implementation of ike_natd_t.has_mapping_changed
+ */
+static bool has_mapping_changed(private_ike_natd_t *this)
+{
+	return this->mapping_changed;
+}
+
+/**
+ * Implementation of task_t.destroy
+ */
+static void destroy(private_ike_natd_t *this)
+{
+	DESTROY_IF(this->hasher);
+	free(this);
+}
+
+/*
+ * Described in header.
+ */
+ike_natd_t *ike_natd_create(ike_sa_t *ike_sa, bool initiator)
+{
+	private_ike_natd_t *this = malloc_thing(private_ike_natd_t);
+
+	this->public.task.get_type = (task_type_t(*)(task_t*))get_type;
+	this->public.task.migrate = (void(*)(task_t*,ike_sa_t*))migrate;
+	this->public.task.destroy = (void(*)(task_t*))destroy;
+
+	if (initiator)
+	{
+		this->public.task.build = (status_t(*)(task_t*,message_t*))build_i;
+		this->public.task.process = (status_t(*)(task_t*,message_t*))process_i;
+	}
+	else
+	{
+		this->public.task.build = (status_t(*)(task_t*,message_t*))build_r;
+		this->public.task.process = (status_t(*)(task_t*,message_t*))process_r;
+	}
+
+	this->public.has_mapping_changed = (bool(*)(ike_natd_t*))has_mapping_changed;
+
+	this->ike_sa = ike_sa;
+	this->initiator = initiator;
+	this->hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1);
+	this->src_seen = FALSE;
+	this->dst_seen = FALSE;
+	this->src_matched = FALSE;
+	this->dst_matched = FALSE;
+	this->mapping_changed = FALSE;
+
+	return &this->public;
+}