Remove all ESP proposals with non-matching DH group during Quick Mode

According to RFC 2409, section 5.5, if PFS is used all proposals MUST
include the selected DH group, so we remove proposals without the
proposed group and remove other DH groups from the remaining proposals.

1 files changed, 22 insertions, 10 deletions

diff --git a/src/libcharon/sa/ikev1/tasks/quick_mode.c b/src/libcharon/sa/ikev1/tasks/quick_mode.c
index 82a7238c3..079589475 100644
--- a/src/libcharon/sa/ikev1/tasks/quick_mode.c
+++ b/src/libcharon/sa/ikev1/tasks/quick_mode.c
@@ -735,11 +735,33 @@ METHOD(task_t, build_i, status_t,
 				DBG1(DBG_IKE, "allocating SPI from kernel failed");
 				return FAILED;
 			}
+			group = this->config->get_dh_group(this->config);
+			if (group != MODP_NONE)
+			{
+				this->dh = this->keymat->keymat.create_dh(&this->keymat->keymat,
+														  group);
+				if (!this->dh)
+				{
+					DBG1(DBG_IKE, "configured DH group %N not supported",
+						 diffie_hellman_group_names, group);
+					return FAILED;
+				}
+			}
 
 			list = this->config->get_proposals(this->config, FALSE);
 			enumerator = list->create_enumerator(list);
 			while (enumerator->enumerate(enumerator, &proposal))
 			{
+				if (group != MODP_NONE)
+				{
+					if (!proposal->has_dh_group(proposal, group))
+					{
+						list->remove_at(list, enumerator);
+						proposal->destroy(proposal);
+						continue;
+					}
+					proposal->strip_dh(proposal, group);
+				}
 				proposal->set_spi(proposal, this->spi_i);
 			}
 			enumerator->destroy(enumerator);
@@ -755,18 +777,8 @@ METHOD(task_t, build_i, status_t,
 			{
 				return FAILED;
 			}
-
-			group = this->config->get_dh_group(this->config);
 			if (group != MODP_NONE)
 			{
-				this->dh = this->keymat->keymat.create_dh(&this->keymat->keymat,
-														  group);
-				if (!this->dh)
-				{
-					DBG1(DBG_IKE, "configured DH group %N not supported",
-						 diffie_hellman_group_names, group);
-					return FAILED;
-				}
 				add_ke(this, message);
 			}
 			if (!this->tsi)