added PDF support for CHILD_SAs

support for INVALID_KE_PAYLOAD negotiation for rekeying

11 files changed, 361 insertions, 190 deletions

diff --git a/src/charon/config/child_cfg.c b/src/charon/config/child_cfg.c
index 2f5376753..440f7710b 100644
--- a/src/charon/config/child_cfg.c
+++ b/src/charon/config/child_cfg.c
@@ -120,9 +120,26 @@ static void add_proposal(private_child_cfg_t *this, proposal_t *proposal)
 }
 
 /**
+ * strip out DH groups from a proposal
+ */
+static void strip_dh_from_proposal(proposal_t *proposal)
+{
+	iterator_t *iterator;
+	algorithm_t *algo;
+	
+	iterator = proposal->create_algorithm_iterator(proposal, DIFFIE_HELLMAN_GROUP);
+	while (iterator->iterate(iterator, (void**)&algo))
+	{
+		iterator->remove(iterator);
+		free(algo);
+	}
+	iterator->destroy(iterator);
+}
+
+/**
  * Implementation of child_cfg_t.get_proposals
  */
-static linked_list_t* get_proposals(private_child_cfg_t *this)
+static linked_list_t* get_proposals(private_child_cfg_t *this, bool strip_dh)
 {
 	iterator_t *iterator;
 	proposal_t *current;
@@ -132,6 +149,10 @@ static linked_list_t* get_proposals(private_child_cfg_t *this)
 	while (iterator->iterate(iterator, (void**)&current))
 	{
 		current = current->clone(current);
+		if (strip_dh)
+		{
+			strip_dh_from_proposal(current);
+		}
 		proposals->insert_last(proposals, current);
 	}
 	iterator->destroy(iterator);
@@ -142,7 +163,8 @@ static linked_list_t* get_proposals(private_child_cfg_t *this)
 /**
  * Implementation of child_cfg_t.get_name
  */
-static proposal_t* select_proposal(private_child_cfg_t*this, linked_list_t *proposals)
+static proposal_t* select_proposal(private_child_cfg_t*this,
+								   linked_list_t *proposals, bool strip_dh)
 {
 	iterator_t *stored_iter, *supplied_iter;
 	proposal_t *stored, *supplied, *selected = NULL;
@@ -156,7 +178,18 @@ static proposal_t* select_proposal(private_child_cfg_t*this, linked_list_t *prop
 		supplied_iter->reset(supplied_iter);
 		while (supplied_iter->iterate(supplied_iter, (void**)&supplied))
 		{
-			selected = stored->select(stored, supplied);
+			if (strip_dh)
+			{
+				/* remove DH groups on a copy */
+				stored = stored->clone(stored);
+				strip_dh_from_proposal(stored);
+				selected = stored->select(stored, supplied);
+				stored->destroy(stored);
+			}
+			else
+			{
+				selected = stored->select(stored, supplied);
+			}
 			if (selected)
 			{
 				break;
@@ -329,6 +362,29 @@ static mode_t get_mode(private_child_cfg_t *this)
 }
 
 /**
+ * Implementation of child_cfg_t.get_dh_group.
+ */
+static diffie_hellman_group_t get_dh_group(private_child_cfg_t *this)
+{
+	iterator_t *iterator;
+	proposal_t *proposal;
+	algorithm_t *algo;
+	diffie_hellman_group_t dh_group = MODP_NONE;
+	
+	iterator = this->proposals->create_iterator(this->proposals, TRUE);
+	while (iterator->iterate(iterator, (void**)&proposal))
+	{
+		if (proposal->get_algorithm(proposal, DIFFIE_HELLMAN_GROUP, &algo))
+		{
+			dh_group = algo->algorithm;
+			break;
+		}
+	}
+	iterator->destroy(iterator);
+	return dh_group;
+}
+
+/**
  * Implementation of child_cfg_t.get_name
  */
 static void get_ref(private_child_cfg_t *this)
@@ -369,12 +425,13 @@ child_cfg_t *child_cfg_create(char *name, u_int32_t lifetime,
 	this->public.add_traffic_selector = (void (*)(child_cfg_t*,bool,traffic_selector_t*))add_traffic_selector;
 	this->public.get_traffic_selectors = (linked_list_t*(*)(child_cfg_t*,bool,linked_list_t*,host_t*))get_traffic_selectors;
 	this->public.add_proposal = (void (*) (child_cfg_t*,proposal_t*))add_proposal;
-	this->public.get_proposals = (linked_list_t* (*) (child_cfg_t*))get_proposals;
-	this->public.select_proposal = (proposal_t* (*) (child_cfg_t*,linked_list_t*))select_proposal;
+	this->public.get_proposals = (linked_list_t* (*) (child_cfg_t*,bool))get_proposals;
+	this->public.select_proposal = (proposal_t* (*) (child_cfg_t*,linked_list_t*,bool))select_proposal;
 	this->public.get_updown = (char* (*) (child_cfg_t*))get_updown;
 	this->public.get_hostaccess = (bool (*) (child_cfg_t*))get_hostaccess;
 	this->public.get_mode = (mode_t (*) (child_cfg_t *))get_mode;
 	this->public.get_lifetime = (u_int32_t (*) (child_cfg_t *,bool))get_lifetime;
+	this->public.get_dh_group = (diffie_hellman_group_t(*)(child_cfg_t*)) get_dh_group;
 	this->public.get_ref = (void (*) (child_cfg_t*))get_ref;
 	this->public.destroy = (void (*) (child_cfg_t*))destroy;
 	
diff --git a/src/charon/config/child_cfg.h b/src/charon/config/child_cfg.h
index 6b2299089..e1a6553b4 100644
--- a/src/charon/config/child_cfg.h
+++ b/src/charon/config/child_cfg.h
@@ -96,9 +96,10 @@ struct child_cfg_t {
 	 * Resulting list and all of its proposals must be freed after use.
 	 * 
 	 * @param this			calling object
+	 * @param strip_dh		TRUE strip out diffie hellman groups
 	 * @return				list of proposals
 	 */
-	linked_list_t* (*get_proposals)(child_cfg_t *this);
+	linked_list_t* (*get_proposals)(child_cfg_t *this, bool strip_dh);
 	
 	/**
 	 * @brief Select a proposal from a supplied list.
@@ -107,9 +108,11 @@ struct child_cfg_t {
 	 * 
 	 * @param this			calling object
 	 * @param proposals		list from from wich proposals are selected
+	 * @param strip_dh		TRUE strip out diffie hellman groups
 	 * @return				selected proposal, or NULL if nothing matches
 	 */
-	proposal_t* (*select_proposal)(child_cfg_t*this, linked_list_t *proposals);
+	proposal_t* (*select_proposal)(child_cfg_t*this, linked_list_t *proposals,
+								   bool strip_dh);
 	
 	/**
 	 * @brief Add a traffic selector to the config.
@@ -189,6 +192,14 @@ struct child_cfg_t {
 	mode_t (*get_mode) (child_cfg_t *this);
 	
 	/**
+	 * @brief Get the DH group to use for CHILD_SA setup.
+	 * 
+	 * @param this		calling object
+	 * @return			dh group to use
+	 */
+	diffie_hellman_group_t (*get_dh_group)(child_cfg_t *this);
+	
+	/**
 	 * @brief Get a new reference.
 	 *
 	 * Get a new reference to this child_cfg by increasing
diff --git a/src/charon/config/ike_cfg.c b/src/charon/config/ike_cfg.c
index 61e62115d..35f46a6b7 100644
--- a/src/charon/config/ike_cfg.c
+++ b/src/charon/config/ike_cfg.c
@@ -176,36 +176,6 @@ static diffie_hellman_group_t get_dh_group(private_ike_cfg_t *this)
 }
 
 /**
- * Implementation of ike_cfg_t.check_dh_group.
- */
-static bool check_dh_group(private_ike_cfg_t *this,
-						   diffie_hellman_group_t dh_group)
-{
-	iterator_t *prop_iter, *alg_iter;
-	proposal_t *proposal;
-	algorithm_t *algo;
-	
-	prop_iter = this->proposals->create_iterator(this->proposals, TRUE);
-	while (prop_iter->iterate(prop_iter, (void**)&proposal))
-	{
-		alg_iter = proposal->create_algorithm_iterator(proposal,
-													   DIFFIE_HELLMAN_GROUP);
-		while (alg_iter->iterate(alg_iter, (void**)&algo))
-		{
-			if (algo->algorithm == dh_group)
-			{
-				prop_iter->destroy(prop_iter);
-				alg_iter->destroy(alg_iter);
-				return TRUE;
-			}
-		}
-		alg_iter->destroy(alg_iter);
-	}
-	prop_iter->destroy(prop_iter);
-	return FALSE;
-}
-
-/**
  * Implementation of ike_cfg_t.get_ref.
  */
 static void get_ref(private_ike_cfg_t *this)
@@ -243,7 +213,6 @@ ike_cfg_t *ike_cfg_create(bool certreq, host_t *my_host, host_t *other_host)
 	this->public.get_proposals = (linked_list_t*(*)(ike_cfg_t*))get_proposals;
 	this->public.select_proposal = (proposal_t*(*)(ike_cfg_t*,linked_list_t*))select_proposal;
 	this->public.get_dh_group = (diffie_hellman_group_t(*)(ike_cfg_t*)) get_dh_group;
-	this->public.check_dh_group = (bool(*)(ike_cfg_t*,diffie_hellman_group_t)) check_dh_group;
 	this->public.get_ref = (void(*)(ike_cfg_t*))get_ref;
 	this->public.destroy = (void(*)(ike_cfg_t*))destroy;
 	
diff --git a/src/charon/config/ike_cfg.h b/src/charon/config/ike_cfg.h
index ccea0a527..bcdc90d9e 100644
--- a/src/charon/config/ike_cfg.h
+++ b/src/charon/config/ike_cfg.h
@@ -110,17 +110,6 @@ struct ike_cfg_t {
 	diffie_hellman_group_t (*get_dh_group)(ike_cfg_t *this);
 	
 	/**
-	 * @brief Check if a suggested DH group is acceptable.
-	 * 
-	 * If we guess a wrong DH group for IKE_SA_INIT, the other
-	 * peer will send us a offer. But is this acceptable for us?
-	 * 
-	 * @param this		calling object
-	 * @return			TRUE if group acceptable
-	 */
-	bool (*check_dh_group) (ike_cfg_t *this, diffie_hellman_group_t dh_group);
-	
-	/**
 	 * @brief Get a new reference to this ike_cfg.
 	 *
 	 * Get a new reference to this ike_cfg by increasing
diff --git a/src/charon/config/proposal.c b/src/charon/config/proposal.c
index dcab8cbdd..fe113b1d8 100644
--- a/src/charon/config/proposal.c
+++ b/src/charon/config/proposal.c
@@ -144,39 +144,6 @@ static void add_algorithm(private_proposal_t *this, transform_type_t type, u_int
 }
 
 /**
- * Implements proposal_t.get_algorithm.
- */
-static bool get_algorithm(private_proposal_t *this, transform_type_t type, algorithm_t** algo)
-{
-	linked_list_t *list;
-	switch (type)
-	{
-		case ENCRYPTION_ALGORITHM:
-			list = this->encryption_algos;
-			break;
-		case INTEGRITY_ALGORITHM:
-			list = this->integrity_algos;
-			break;
-		case PSEUDO_RANDOM_FUNCTION:
-			list = this->prf_algos;
-			break;
-		case DIFFIE_HELLMAN_GROUP:
-			list = this->dh_groups;
-			break;
-		case EXTENDED_SEQUENCE_NUMBERS:
-			list = this->esns;
-			break;
-		default:
-			return FALSE;
-	}
-	if (list->get_first(list, (void**)algo) != SUCCESS)
-	{
-		return FALSE;
-	}
-	return TRUE;
-}
-
-/**
  * Implements proposal_t.create_algorithm_iterator.
  */
 static iterator_t *create_algorithm_iterator(private_proposal_t *this, transform_type_t type)
@@ -200,6 +167,50 @@ static iterator_t *create_algorithm_iterator(private_proposal_t *this, transform
 }
 
 /**
+ * Implements proposal_t.get_algorithm.
+ */
+static bool get_algorithm(private_proposal_t *this, transform_type_t type, algorithm_t** algo)
+{
+	iterator_t *iterator = create_algorithm_iterator(this, type);
+	if (iterator->iterate(iterator, (void**)algo))
+	{
+		iterator->destroy(iterator);
+		return TRUE;
+	}
+	iterator->destroy(iterator);
+	return FALSE;
+}
+
+/**
+ * Implements proposal_t.has_dh_group
+ */
+static bool has_dh_group(private_proposal_t *this, diffie_hellman_group_t group)
+{
+	algorithm_t *current;
+	iterator_t *iterator;
+	bool result = FALSE;
+	
+	iterator = this->dh_groups->create_iterator(this->dh_groups, TRUE);
+	if (iterator->get_count(iterator))
+	{
+		while (iterator->iterate(iterator, (void**)&current))
+		{
+			if (current->algorithm == group)
+			{
+				result = TRUE;
+				break;
+			}
+		}
+	}
+	else if (group == MODP_NONE)
+	{
+		result = TRUE;
+	}
+	iterator->destroy(iterator);
+	return result;
+}
+
+/**
  * Find a matching alg/keysize in two linked lists
  */
 static bool select_algo(linked_list_t *first, linked_list_t *second, bool *add, u_int16_t *alg, size_t *key_size)
@@ -530,6 +541,7 @@ proposal_t *proposal_create(protocol_id_t protocol)
 	this->public.add_algorithm = (void (*)(proposal_t*,transform_type_t,u_int16_t,size_t))add_algorithm;
 	this->public.create_algorithm_iterator = (iterator_t* (*)(proposal_t*,transform_type_t))create_algorithm_iterator;
 	this->public.get_algorithm = (bool (*)(proposal_t*,transform_type_t,algorithm_t**))get_algorithm;
+	this->public.has_dh_group = (bool (*)(proposal_t*,diffie_hellman_group_t))has_dh_group;
 	this->public.select = (proposal_t* (*)(proposal_t*,proposal_t*))select_proposal;
 	this->public.get_protocol = (protocol_id_t(*)(proposal_t*))get_protocol;
 	this->public.set_spi = (void(*)(proposal_t*,u_int64_t))set_spi;
diff --git a/src/charon/config/proposal.h b/src/charon/config/proposal.h
index 4bee08e28..379550f44 100644
--- a/src/charon/config/proposal.h
+++ b/src/charon/config/proposal.h
@@ -164,7 +164,6 @@ struct proposal_t {
 	 * @brief Get the algorithm for a type to use.
 	 * 
 	 * If there are multiple algorithms, only the first is returned.
-	 * Result is still owned by proposal, do not modify!
 	 * 
 	 * @param this					calling object
 	 * @param type					kind of algorithm
@@ -172,6 +171,15 @@ struct proposal_t {
 	 * @return						TRUE if algorithm of this kind available
 	 */
 	bool (*get_algorithm) (proposal_t *this, transform_type_t type, algorithm_t** algo);
+	
+	/**
+	 * @brief Check if the proposal has a specific DH group.
+	 * 
+	 * @param this					calling object
+	 * @param group					group to check for
+	 * @return						TRUE if algorithm included
+	 */
+	bool (*has_dh_group) (proposal_t *this, diffie_hellman_group_t group);
 
 	/**
 	 * @brief Compare two proposal, and select a matching subset.
diff --git a/src/charon/sa/task_manager.c b/src/charon/sa/task_manager.c
index 9633ba740..eb707c1f9 100644
--- a/src/charon/sa/task_manager.c
+++ b/src/charon/sa/task_manager.c
@@ -279,7 +279,6 @@ static status_t build_request(private_task_manager_t *this)
 				if (activate_task(this, CHILD_CREATE))
 				{
 					exchange = CREATE_CHILD_SA;
-					activate_task(this, IKE_CONFIG);
 					break;
 				}
 				if (activate_task(this, CHILD_DELETE))
@@ -333,6 +332,11 @@ static status_t build_request(private_task_manager_t *this)
 				case IKE_AUTHENTICATE:
 					exchange = IKE_AUTH;
 					break;
+				case CHILD_CREATE:
+				case CHILD_REKEY:
+				case IKE_REKEY:
+					exchange = CREATE_CHILD_SA;
+					break;
 				default:
 					continue;
 			}
diff --git a/src/charon/sa/tasks/child_create.c b/src/charon/sa/tasks/child_create.c
index 5ed9791ab..ac03a33fe 100644
--- a/src/charon/sa/tasks/child_create.c
+++ b/src/charon/sa/tasks/child_create.c
@@ -26,6 +26,7 @@
 #include <daemon.h>
 #include <crypto/diffie_hellman.h>
 #include <encoding/payloads/sa_payload.h>
+#include <encoding/payloads/ke_payload.h>
 #include <encoding/payloads/ts_payload.h>
 #include <encoding/payloads/nonce_payload.h>
 #include <encoding/payloads/notify_payload.h>
@@ -89,6 +90,16 @@ struct private_child_create_t {
 	linked_list_t *tsr;
 	
 	/**
+	 * optional diffie hellman exchange
+	 */
+	diffie_hellman_t *dh;
+	
+	/**
+	 * group used for DH exchange
+	 */
+	diffie_hellman_group_t dh_group;
+	
+	/**
 	 * mode the new CHILD_SA uses (transport/tunnel/beet)
 	 */
 	mode_t mode;
@@ -162,21 +173,29 @@ static bool ts_list_is_host(linked_list_t *list, host_t *host)
 }
 
 /**
- * Install a CHILD_SA for usage
+ * Install a CHILD_SA for usage, return value:
+ * - FAILED: no acceptable proposal
+ * - INVALID_ARG: diffie hellman group inacceptable
+ * - NOT_FOUND: TS inacceptable
  */
-static status_t select_and_install(private_child_create_t *this)
+static status_t select_and_install(private_child_create_t *this, bool no_dh)
 {
 	prf_plus_t *prf_plus;
 	status_t status;
-	chunk_t nonce_i, nonce_r, seed;
+	chunk_t nonce_i, nonce_r, secret, seed;
 	linked_list_t *my_ts, *other_ts;
 	host_t *me, *other, *other_vip, *my_vip;
 	
-	if (this->proposals == NULL || this->tsi == NULL || this->tsr == NULL)
+	if (this->proposals == NULL)
 	{
-		SIG(CHILD_UP_FAILED, "SA/TS payloads missing in message");
+		SIG(CHILD_UP_FAILED, "SA payload missing in message");
 		return FAILED;
 	}
+	if (this->tsi == NULL || this->tsr == NULL)
+	{
+		SIG(CHILD_UP_FAILED, "TS payloads missing in message");
+		return NOT_FOUND;
+	}
 	
 	if (this->initiator)
 	{
@@ -198,14 +217,34 @@ static status_t select_and_install(private_child_create_t *this)
 	my_vip = this->ike_sa->get_virtual_ip(this->ike_sa, TRUE);
 	other_vip = this->ike_sa->get_virtual_ip(this->ike_sa, FALSE);
 
-	this->proposal = this->config->select_proposal(this->config, this->proposals);
-	
+	this->proposal = this->config->select_proposal(this->config, this->proposals,
+												   no_dh);
 	if (this->proposal == NULL)
 	{
 		SIG(CHILD_UP_FAILED, "no acceptable proposal found");
 		return FAILED;
 	}
 	
+	if (!this->proposal->has_dh_group(this->proposal, this->dh_group))
+	{
+		algorithm_t *algo;
+		if (this->proposal->get_algorithm(this->proposal, DIFFIE_HELLMAN_GROUP,
+										  &algo))
+		{
+			u_int16_t group = algo->algorithm;
+			SIG(CHILD_UP_FAILED, "DH group %N inacceptable, requesting %N",
+				diffie_hellman_group_names, this->dh_group,
+				diffie_hellman_group_names, group);
+			this->dh_group = group;
+			return INVALID_ARG;
+		}
+		else
+		{
+			SIG(CHILD_UP_FAILED, "no acceptable proposal found");
+			return FAILED;
+		}
+	}
+	
 	if (my_vip == NULL)
 	{
 		my_vip = me;
@@ -228,7 +267,7 @@ static status_t select_and_install(private_child_create_t *this)
 	if (my_ts->get_count(my_ts) == 0 || other_ts->get_count(other_ts) == 0)
 	{
 		SIG(CHILD_UP_FAILED, "no acceptable traffic selectors found");
-		return FAILED;
+		return NOT_FOUND;
 	}
 	
 	this->tsr->destroy_offset(this->tsr, offsetof(traffic_selector_t, destroy));
@@ -275,7 +314,20 @@ static status_t select_and_install(private_child_create_t *this)
 		}
 	}
 	
-	seed = chunk_cata("cc", nonce_i, nonce_r);
+	if (this->dh)
+	{
+		if (this->dh->get_shared_secret(this->dh, &secret) != SUCCESS)
+		{
+			SIG(CHILD_UP_FAILED, "DH exchange incomplete");
+			return FAILED;
+		}
+		DBG3(DBG_IKE, "DH secret %B", &secret);
+		seed = chunk_cata("mcc", secret, nonce_i, nonce_r);
+	}
+	else
+	{
+		seed = chunk_cata("cc", nonce_i, nonce_r);
+	}
 	prf_plus = prf_plus_create(this->ike_sa->get_child_prf(this->ike_sa), seed);
 	
 	if (this->initiator)
@@ -293,7 +345,7 @@ static status_t select_and_install(private_child_create_t *this)
 	if (status != SUCCESS)
 	{
 		SIG(CHILD_UP_FAILED, "unable to install IPsec SA (SAD) in kernel");
-		return status;
+		return FAILED;
 	}
 	
 	status = this->child_sa->add_policies(this->child_sa, my_ts, other_ts,
@@ -302,7 +354,7 @@ static status_t select_and_install(private_child_create_t *this)
 	if (status != SUCCESS)
 	{	
 		SIG(CHILD_UP_FAILED, "unable to install IPsec policies (SPD) in kernel");
-		return status;
+		return NOT_FOUND;
 	}
 	/* add to IKE_SA, and remove from task */
 	this->child_sa->set_state(this->child_sa, CHILD_INSTALLED);
@@ -317,8 +369,9 @@ static status_t select_and_install(private_child_create_t *this)
 static void build_payloads(private_child_create_t *this, message_t *message)
 {
 	sa_payload_t *sa_payload;
-	ts_payload_t *ts_payload;
 	nonce_payload_t *nonce_payload;
+	ke_payload_t *ke_payload;
+	ts_payload_t *ts_payload;
 
 	/* add SA payload */
 	if (this->initiator)
@@ -339,6 +392,13 @@ static void build_payloads(private_child_create_t *this, message_t *message)
 		message->add_payload(message, (payload_t*)nonce_payload);
 	}
 	
+	/* diffie hellman exchange, if PFS enabled */
+	if (this->dh)
+	{
+		ke_payload = ke_payload_create_from_diffie_hellman(this->dh);
+		message->add_payload(message, (payload_t*)ke_payload);
+	}
+	
 	/* add TSi/TSr payloads */
 	ts_payload = ts_payload_create_from_traffic_selectors(TRUE, this->tsi);
 	message->add_payload(message, (payload_t*)ts_payload);
@@ -367,6 +427,7 @@ static void process_payloads(private_child_create_t *this, message_t *message)
 	iterator_t *iterator;
 	payload_t *payload;
 	sa_payload_t *sa_payload;
+	ke_payload_t *ke_payload;
 	ts_payload_t *ts_payload;
 	notify_payload_t *notify_payload;
 	
@@ -382,6 +443,19 @@ static void process_payloads(private_child_create_t *this, message_t *message)
 				sa_payload = (sa_payload_t*)payload;
 				this->proposals = sa_payload->get_proposals(sa_payload);
 				break;
+			case KEY_EXCHANGE:
+				ke_payload = (ke_payload_t*)payload;
+				if (!this->initiator)
+				{
+					this->dh_group = ke_payload->get_dh_group_number(ke_payload);
+					this->dh = diffie_hellman_create(this->dh_group);
+				}
+				if (this->dh)
+				{
+					this->dh->set_other_public_value(this->dh,
+								ke_payload->get_key_exchange_data(ke_payload));
+				}
+				break;
 			case TRAFFIC_SELECTOR_INITIATOR:
 				ts_payload = (ts_payload_t*)payload;
 				this->tsi = ts_payload->get_traffic_selectors(ts_payload);
@@ -429,6 +503,10 @@ static status_t build_i(private_child_create_t *this, message_t *message)
 				message->add_notify(message, FALSE, NO_PROPOSAL_CHOSEN, chunk_empty);
 				return SUCCESS;
 			}
+			if (this->dh_group == MODP_NONE)
+			{
+				this->dh_group = this->config->get_dh_group(this->config);
+			}
 			break;
 		case IKE_AUTH:
 			if (!message->get_payload(message, ID_INITIATOR))
@@ -461,7 +539,8 @@ static status_t build_i(private_child_create_t *this, message_t *message)
 	}
 	this->tsr = this->config->get_traffic_selectors(this->config, FALSE, 
 													NULL, other);
-	this->proposals = this->config->get_proposals(this->config);
+	this->proposals = this->config->get_proposals(this->config,
+												  this->dh_group == MODP_NONE);
 	this->mode = this->config->get_mode(this->config);
 	
 	this->child_sa = child_sa_create(me, other,
@@ -476,6 +555,11 @@ static status_t build_i(private_child_create_t *this, message_t *message)
 		return FAILED;
 	}
 	
+	if (this->dh_group != MODP_NONE)
+	{
+		this->dh = diffie_hellman_create(this->dh_group);
+	}
+	
 	build_payloads(this, message);
 	
 	this->tsi->destroy_offset(this->tsi, offsetof(traffic_selector_t, destroy));
@@ -535,6 +619,8 @@ static status_t process_r(private_child_create_t *this, message_t *message)
  */
 static status_t build_r(private_child_create_t *this, message_t *message)
 {
+	bool no_dh = TRUE;
+
 	switch (message->get_exchange_type(message))
 	{
 		case IKE_SA_INIT:
@@ -545,6 +631,7 @@ static status_t build_r(private_child_create_t *this, message_t *message)
 				message->add_notify(message, FALSE, NO_PROPOSAL_CHOSEN, chunk_empty);
 				return SUCCESS;
 			}
+			no_dh = FALSE;
 			break;
 		case IKE_AUTH:
 			if (message->get_payload(message, EXTENSIBLE_AUTHENTICATION))
@@ -578,10 +665,24 @@ static status_t build_r(private_child_create_t *this, message_t *message)
 									 this->config, this->reqid,
 									 this->ike_sa->is_natt_enabled(this->ike_sa));
 	
-	if (select_and_install(this) != SUCCESS)
+	switch (select_and_install(this, no_dh))
 	{
-		message->add_notify(message, FALSE, NO_PROPOSAL_CHOSEN, chunk_empty);
-		return SUCCESS;
+		case SUCCESS:
+			break;
+		case NOT_FOUND:
+			message->add_notify(message, FALSE, TS_UNACCEPTABLE, chunk_empty);
+			return SUCCESS;
+		case INVALID_ARG:
+		{
+			u_int16_t group = htons(this->dh_group);
+			message->add_notify(message, FALSE, INVALID_KE_PAYLOAD,
+								chunk_from_thing(group));
+			return SUCCESS;
+		}
+		case FAILED:
+		default:
+			message->add_notify(message, FALSE, NO_PROPOSAL_CHOSEN, chunk_empty);
+			return SUCCESS;
 	}
 	
 	build_payloads(this, message);
@@ -598,6 +699,7 @@ static status_t process_i(private_child_create_t *this, message_t *message)
 {
 	iterator_t *iterator;
 	payload_t *payload;
+	bool no_dh = TRUE;
 
 	switch (message->get_exchange_type(message))
 	{
@@ -605,6 +707,7 @@ static status_t process_i(private_child_create_t *this, message_t *message)
 			return get_nonce(message, &this->other_nonce);
 		case CREATE_CHILD_SA:
 			get_nonce(message, &this->other_nonce);
+			no_dh = FALSE;
 			break;
 		case IKE_AUTH:
 			if (message->get_payload(message, EXTENSIBLE_AUTHENTICATION))
@@ -642,6 +745,22 @@ static status_t process_i(private_child_create_t *this, message_t *message)
 					/* an error in CHILD_SA creation is not critical */
 					return SUCCESS;
 				}
+				case INVALID_KE_PAYLOAD:
+				{
+					chunk_t data;
+					diffie_hellman_group_t bad_group;
+					
+					bad_group = this->dh_group;
+					data = notify->get_notification_data(notify);
+					this->dh_group = ntohs(*((u_int16_t*)data.ptr));
+					DBG1(DBG_IKE, "peer didn't accept DH group %N, "
+						 "it requested %N", diffie_hellman_group_names,
+						 bad_group, diffie_hellman_group_names, this->dh_group);
+					
+					this->public.task.migrate(&this->public.task, this->ike_sa);
+					iterator->destroy(iterator);
+					return NEED_MORE;
+				}
 				default:
 					break;
 			}
@@ -651,7 +770,7 @@ static status_t process_i(private_child_create_t *this, message_t *message)
 	
 	process_payloads(this, message);
 	
-	if (select_and_install(this) == SUCCESS)
+	if (select_and_install(this, no_dh) == SUCCESS)
 	{
 		SIG(CHILD_UP_SUCCESS, "established CHILD_SA successfully");
 	}
@@ -715,6 +834,7 @@ static void migrate(private_child_create_t *this, ike_sa_t *ike_sa)
 	}
 	DESTROY_IF(this->child_sa);
 	DESTROY_IF(this->proposal);
+	DESTROY_IF(this->dh);
 	if (this->proposals)
 	{
 		this->proposals->destroy_offset(this->proposals, offsetof(proposal_t, destroy));
@@ -724,6 +844,7 @@ static void migrate(private_child_create_t *this, ike_sa_t *ike_sa)
 	this->proposals = NULL;
 	this->tsi = NULL;
 	this->tsr = NULL;
+	this->dh = NULL;
 	this->child_sa = NULL;
 	this->mode = MODE_TUNNEL;
 	this->reqid = 0;
@@ -750,6 +871,7 @@ static void destroy(private_child_create_t *this)
 		DESTROY_IF(this->child_sa);
 	}
 	DESTROY_IF(this->proposal);
+	DESTROY_IF(this->dh);
 	if (this->proposals)
 	{
 		this->proposals->destroy_offset(this->proposals, offsetof(proposal_t, destroy));
@@ -794,6 +916,8 @@ child_create_t *child_create_create(ike_sa_t *ike_sa, child_cfg_t *config)
 	this->proposal = NULL;
 	this->tsi = NULL;
 	this->tsr = NULL;
+	this->dh = NULL;
+	this->dh_group = MODP_NONE;
 	this->child_sa = NULL;
 	this->mode = MODE_TUNNEL;
 	this->reqid = 0;
diff --git a/src/charon/sa/tasks/child_rekey.c b/src/charon/sa/tasks/child_rekey.c
index 1621357cc..4f3c69034 100644
--- a/src/charon/sa/tasks/child_rekey.c
+++ b/src/charon/sa/tasks/child_rekey.c
@@ -183,7 +183,12 @@ static status_t process_i(private_child_rekey_t *this, message_t *message)
 	u_int32_t spi;
 	child_sa_t *to_delete;
 	
-	this->child_create->task.process(&this->child_create->task, message);
+	if (this->child_create->task.process(&this->child_create->task, message) == NEED_MORE)
+	{
+		/* bad DH group while rekeying, try again */
+		this->child_create->task.migrate(&this->child_create->task, this->ike_sa);
+		return NEED_MORE;
+	}
 	if (message->get_payload(message, SECURITY_ASSOCIATION) == NULL)
 	{
 		/* establishing new child failed, reuse old. but not when we
diff --git a/src/charon/sa/tasks/ike_init.c b/src/charon/sa/tasks/ike_init.c
index 8165a01a2..f78b5dd66 100644
--- a/src/charon/sa/tasks/ike_init.c
+++ b/src/charon/sa/tasks/ike_init.c
@@ -69,7 +69,7 @@ struct private_ike_init_t {
 	/**
 	 * Diffie hellman object used to generate public DH value.
 	 */
-	diffie_hellman_t *diffie_hellman;
+	diffie_hellman_t *dh;
 	
 	/**
 	 * nonce chosen by us
@@ -151,7 +151,7 @@ static void build_payloads(private_ike_init_t *this, message_t *message)
 	nonce_payload->set_nonce(nonce_payload, this->my_nonce);
 	message->add_payload(message, (payload_t*)nonce_payload);
 	
-	ke_payload = ke_payload_create_from_diffie_hellman(this->diffie_hellman);
+	ke_payload = ke_payload_create_from_diffie_hellman(this->dh);
 	message->add_payload(message, (payload_t*)ke_payload);
 }
 
@@ -183,33 +183,16 @@ static void process_payloads(private_ike_init_t *this, message_t *message)
 			case KEY_EXCHANGE:
 			{
 				ke_payload_t *ke_payload = (ke_payload_t*)payload;
-				diffie_hellman_group_t dh_group;
-				chunk_t key_data;
 				
-				dh_group = ke_payload->get_dh_group_number(ke_payload);
-				
-				if (this->initiator)
-				{
-					if (dh_group != this->dh_group)
-					{
-						DBG1(DBG_IKE, "received a DH group not requested (%N)",
-							 diffie_hellman_group_names, dh_group);
-						break;
-					}
-				}
-				else
+				this->dh_group = ke_payload->get_dh_group_number(ke_payload);
+				if (!this->initiator)
 				{
-					this->dh_group = dh_group;
-					if (!this->config->check_dh_group(this->config, dh_group))
-					{
-						break;
-					}
-					this->diffie_hellman = diffie_hellman_create(dh_group);
+					this->dh = diffie_hellman_create(this->dh_group);
 				}
-				if (this->diffie_hellman)
+				if (this->dh)
 				{
-					key_data = ke_payload->get_key_exchange_data(ke_payload);
-					this->diffie_hellman->set_other_public_value(this->diffie_hellman, key_data);
+					this->dh->set_other_public_value(this->dh,
+								ke_payload->get_key_exchange_data(ke_payload));
 				}
 				break;
 			}
@@ -246,11 +229,11 @@ static status_t build_i(private_ike_init_t *this, message_t *message)
 	}
 
 	/* if the DH group is set via use_dh_group(), we already have a DH object */
-	if (!this->diffie_hellman)
+	if (!this->dh)
 	{
 		this->dh_group = this->config->get_dh_group(this->config);
-		this->diffie_hellman = diffie_hellman_create(this->dh_group);
-		if (this->diffie_hellman == NULL)
+		this->dh = diffie_hellman_create(this->dh_group);
+		if (this->dh == NULL)
 		{
 			SIG(IKE_UP_FAILED, "configured DH group %N not supported",
 				diffie_hellman_group_names, this->dh_group);
@@ -325,25 +308,29 @@ static status_t build_r(private_ike_init_t *this, message_t *message)
 		return FAILED;
 	}
 	
-	if (this->diffie_hellman == NULL ||
-		this->diffie_hellman->get_shared_secret(this->diffie_hellman,
-												&secret) != SUCCESS)
+	if (this->dh == NULL ||
+		!this->proposal->has_dh_group(this->proposal, this->dh_group) ||
+		this->dh->get_shared_secret(this->dh, &secret) != SUCCESS)
 	{
-		chunk_t chunk;
-		u_int16_t dh_enc;
-		
-		SIG(IKE_UP_FAILED, "received inacceptable DH group (%N)",
-			 diffie_hellman_group_names, this->dh_group);
-		this->dh_group = this->config->get_dh_group(this->config);
-		dh_enc = htons(this->dh_group);
-		chunk.ptr = (u_int8_t*)&dh_enc;
-		chunk.len = sizeof(dh_enc);
-		message->add_notify(message, TRUE, INVALID_KE_PAYLOAD, chunk);
-		DBG1(DBG_IKE, "requesting DH group %N",
-			 diffie_hellman_group_names, this->dh_group);
+		algorithm_t *algo;
+		if (this->proposal->get_algorithm(this->proposal, DIFFIE_HELLMAN_GROUP,
+										  &algo))
+		{
+			u_int16_t group = algo->algorithm;
+			SIG(CHILD_UP_FAILED, "DH group %N inacceptable, requesting %N",
+				diffie_hellman_group_names, this->dh_group,
+				diffie_hellman_group_names, group);
+			this->dh_group = group;
+			group = htons(group);
+			message->add_notify(message, FALSE, INVALID_KE_PAYLOAD,
+								chunk_from_thing(group));
+		}
+		else
+		{
+			SIG(IKE_UP_FAILED, "no acceptable proposal found");
+		}
 		return FAILED;
 	}
-
 	
 	if (this->old_sa)
 	{
@@ -404,26 +391,20 @@ static status_t process_i(private_ike_init_t *this, message_t *message)
 				case INVALID_KE_PAYLOAD:
 				{
 					chunk_t data;
-					diffie_hellman_group_t old_dh_group;
+					diffie_hellman_group_t bad_group;
 					
-					old_dh_group = this->dh_group;
+					bad_group = this->dh_group;
 					data = notify->get_notification_data(notify);
 					this->dh_group = ntohs(*((u_int16_t*)data.ptr));
-					
-					DBG1(DBG_IKE, "peer didn't accept DH group %N, it requested"
-						 " %N", diffie_hellman_group_names, old_dh_group,
-						 diffie_hellman_group_names, this->dh_group);
-					if (!this->config->check_dh_group(this->config, this->dh_group))
-					{
-						DBG1(DBG_IKE, "requested DH group %N not acceptable, "
-							"giving up", diffie_hellman_group_names,
-							this->dh_group);
-						iterator->destroy(iterator);
-						return FAILED;
+					DBG1(DBG_IKE, "peer didn't accept DH group %N, "
+						 "it requested %N", diffie_hellman_group_names,
+						 bad_group, diffie_hellman_group_names, this->dh_group);
+						 
+					if (this->old_sa == NULL)
+					{	/* reset the IKE_SA if we are not rekeying */
+						this->ike_sa->reset(this->ike_sa);
 					}
 					
-					this->ike_sa->reset(this->ike_sa);
-					
 					iterator->destroy(iterator);
 					return NEED_MORE;
 				}
@@ -468,9 +449,9 @@ static status_t process_i(private_ike_init_t *this, message_t *message)
 		return FAILED;
 	}
 	
-	if (this->diffie_hellman == NULL ||
-		this->diffie_hellman->get_shared_secret(this->diffie_hellman,
-												&secret) != SUCCESS)
+	if (this->dh == NULL ||
+		!this->proposal->has_dh_group(this->proposal, this->dh_group) ||
+		this->dh->get_shared_secret(this->dh, &secret) != SUCCESS)
 	{
 		SIG(IKE_UP_FAILED, "peers DH group selection invalid");
 		return FAILED;
@@ -537,12 +518,12 @@ static chunk_t get_lower_nonce(private_ike_init_t *this)
 static void migrate(private_ike_init_t *this, ike_sa_t *ike_sa)
 {
 	DESTROY_IF(this->proposal);
-	DESTROY_IF(this->diffie_hellman);
+	DESTROY_IF(this->dh);
 	chunk_free(&this->other_nonce);
 	
 	this->ike_sa = ike_sa;
 	this->proposal = NULL;
-	this->diffie_hellman = diffie_hellman_create(this->dh_group);
+	this->dh = diffie_hellman_create(this->dh_group);
 }
 
 /**
@@ -551,7 +532,7 @@ static void migrate(private_ike_init_t *this, ike_sa_t *ike_sa)
 static void destroy(private_ike_init_t *this)
 {
 	DESTROY_IF(this->proposal);
-	DESTROY_IF(this->diffie_hellman);
+	DESTROY_IF(this->dh);
 	chunk_free(&this->my_nonce);
 	chunk_free(&this->other_nonce);
 	chunk_free(&this->cookie);
@@ -583,7 +564,7 @@ ike_init_t *ike_init_create(ike_sa_t *ike_sa, bool initiator, ike_sa_t *old_sa)
 	this->ike_sa = ike_sa;
 	this->initiator = initiator;
 	this->dh_group = MODP_NONE;
-	this->diffie_hellman = NULL;
+	this->dh = NULL;
 	this->my_nonce = chunk_empty;
 	this->other_nonce = chunk_empty;
 	this->cookie = chunk_empty;
diff --git a/src/charon/sa/tasks/ike_rekey.c b/src/charon/sa/tasks/ike_rekey.c
index 3c3eae5df..d54fc3524 100644
--- a/src/charon/sa/tasks/ike_rekey.c
+++ b/src/charon/sa/tasks/ike_rekey.c
@@ -75,14 +75,18 @@ static status_t build_i(private_ike_rekey_t *this, message_t *message)
 {
 	peer_cfg_t *peer_cfg;
 	
-	this->new_sa = charon->ike_sa_manager->checkout_new(charon->ike_sa_manager,
-														TRUE);
-	
-	peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
-	this->new_sa->set_peer_cfg(this->new_sa, peer_cfg);
-	this->ike_init = ike_init_create(this->new_sa, TRUE, this->ike_sa);
+	/* create new SA only on first try */
+	if (this->new_sa == NULL)
+	{
+		this->new_sa = charon->ike_sa_manager->checkout_new(charon->ike_sa_manager,
+															TRUE);
+		
+		peer_cfg = this->ike_sa->get_peer_cfg(this->ike_sa);
+		this->new_sa->set_peer_cfg(this->new_sa, peer_cfg);
+		this->ike_init = ike_init_create(this->new_sa, TRUE, this->ike_sa);
+		this->ike_sa->set_state(this->ike_sa, IKE_REKEYING);
+	}
 	this->ike_init->task.build(&this->ike_init->task, message);
-	this->ike_sa->set_state(this->ike_sa, IKE_REKEYING);
 
 	return NEED_MORE;
 }
@@ -162,22 +166,29 @@ static status_t process_i(private_ike_rekey_t *this, message_t *message)
 	job_t *job;
 	ike_sa_id_t *to_delete;
 
-	if (this->ike_init->task.process(&this->ike_init->task, message) == FAILED)
+	switch (this->ike_init->task.process(&this->ike_init->task, message))
 	{
-		/* rekeying failed, fallback to old SA */
-		if (!(this->collision &&
-			this->collision->get_type(this->collision) == IKE_DELETE))
-		{
-			job_t *job;
-			u_int32_t retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
-			job = (job_t*)rekey_ike_sa_job_create(
-									this->ike_sa->get_id(this->ike_sa), FALSE);
-			DBG1(DBG_IKE, "IKE_SA rekeying failed, "
-				 					"trying again in %d seconds", retry);
-			this->ike_sa->set_state(this->ike_sa, IKE_ESTABLISHED);
-			charon->event_queue->add_relative(charon->event_queue, job, retry * 1000);
-		}
-		return SUCCESS;
+		case FAILED:
+			/* rekeying failed, fallback to old SA */
+			if (!(this->collision &&
+				this->collision->get_type(this->collision) == IKE_DELETE))
+			{
+				job_t *job;
+				u_int32_t retry = RETRY_INTERVAL - (random() % RETRY_JITTER);
+				job = (job_t*)rekey_ike_sa_job_create(
+										this->ike_sa->get_id(this->ike_sa), FALSE);
+				DBG1(DBG_IKE, "IKE_SA rekeying failed, "
+					 					"trying again in %d seconds", retry);
+				this->ike_sa->set_state(this->ike_sa, IKE_ESTABLISHED);
+				charon->event_queue->add_relative(charon->event_queue, job, retry * 1000);
+			}
+			return SUCCESS;
+		case NEED_MORE:
+			/* bad dh group, try again */
+			this->ike_init->task.migrate(&this->ike_init->task, this->new_sa);
+			return NEED_MORE;
+		default:
+			break;
 	}
 
 	this->new_sa->set_state(this->new_sa, IKE_ESTABLISHED);