charon-tkm: Implement IANA DH Id to TKM Id mapping

The TKM Diffie-Hellman plugin now maps IANA DH identifiers to TKM DH
algorithm identifiers. The mapping is specified in the daemon's
'dh_mapping' section in the strongswan.conf file:

dh_mapping {
	iana_id1 = tkm_id1
	iana_id2 = tkm_id2
	iana_id3 = tkm_id3
	...
}

Only the mapped IANA IDs are registered as supported DH groups.

src/charon-tkm/src/charon-tkm.c

@@ -288,10 +288,6 @@ int main(int argc, char *argv[])
 	static plugin_feature_t features[] = {
 		PLUGIN_REGISTER(NONCE_GEN, tkm_nonceg_create),
 			PLUGIN_PROVIDE(NONCE_GEN),
-		PLUGIN_REGISTER(DH, tkm_diffie_hellman_create),
-			PLUGIN_PROVIDE(DH, MODP_2048_BIT),
-			PLUGIN_PROVIDE(DH, MODP_3072_BIT),
-			PLUGIN_PROVIDE(DH, MODP_4096_BIT),
 		PLUGIN_REGISTER(PUBKEY, tkm_public_key_load, TRUE),
 			PLUGIN_PROVIDE(PUBKEY, KEY_RSA),
 			PLUGIN_PROVIDE(PUBKEY_VERIFY, SIGN_RSA_EMSA_PKCS1_SHA1),
@@ -302,6 +298,12 @@ int main(int argc, char *argv[])
 	lib->plugins->add_static_features(lib->plugins, "tkm-backend", features,
 			countof(features), TRUE);
 
+	if (!register_dh_mapping())
+	{
+		DBG1(DBG_DMN, "no DH group mapping defined - aborting %s", dmn_name);
+		goto deinit;
+	}
+
 	/* register TKM keymat variant */
 	keymat_register_constructor(IKEV2, (keymat_constructor_t)tkm_keymat_create);
 
@@ -380,6 +382,7 @@ int main(int argc, char *argv[])
 	lib->encoding->remove_encoder(lib->encoding, tkm_encoder_encode);
 
 deinit:
+	destroy_dh_mapping();
 	libcharon_deinit();
 	libhydra_deinit();
 	library_deinit();

src/charon-tkm/src/tkm/tkm_diffie_hellman.c

@@ -21,10 +21,13 @@
 #include "tkm_utils.h"
 #include "tkm_diffie_hellman.h"
 
-#include <utils/debug.h>
+#include <daemon.h>
+#include <collections/hashtable.h>
 
 typedef struct private_tkm_diffie_hellman_t private_tkm_diffie_hellman_t;
 
+static hashtable_t *group_map = NULL;
+
 /**
  * Private data of a tkm_diffie_hellman_t object.
  */
@@ -102,6 +105,95 @@ METHOD(tkm_diffie_hellman_t, get_id, dh_id_type,
 	return this->context_id;
 }
 
+static u_int hash(void *key)
+{
+	diffie_hellman_group_t k = *(diffie_hellman_group_t*)key;
+	return chunk_hash(chunk_from_thing(k));
+}
+
+static bool equals(void *key, void *other_key)
+{
+	return *(diffie_hellman_group_t*)key == *(diffie_hellman_group_t*)other_key;
+}
+
+/*
+ * Described in header.
+ */
+int register_dh_mapping()
+{
+	int count, i;
+	char *iana_id_str, *tkm_id_str;
+	diffie_hellman_group_t *iana_id;
+	u_int64_t *tkm_id;
+	hashtable_t *map;
+	enumerator_t *enumerator;
+
+	map = hashtable_create((hashtable_hash_t)hash,
+						   (hashtable_equals_t)equals, 16);
+
+	enumerator = lib->settings->create_key_value_enumerator(lib->settings,
+															"%s.dh_mapping",
+															charon->name);
+
+	while (enumerator->enumerate(enumerator, &iana_id_str, &tkm_id_str))
+	{
+		iana_id = malloc_thing(diffie_hellman_group_t);
+		*iana_id = settings_value_as_int(iana_id_str, 0);
+		tkm_id = malloc_thing(u_int64_t);
+		*tkm_id = settings_value_as_int(tkm_id_str, 0);
+
+		map->put(map, iana_id, tkm_id);
+	}
+	enumerator->destroy(enumerator);
+
+	count = map->get_count(map);
+	plugin_feature_t f[count + 1];
+	f[0] = PLUGIN_REGISTER(DH, tkm_diffie_hellman_create);
+
+	i = 1;
+	enumerator = map->create_enumerator(map);
+	while (enumerator->enumerate(enumerator, &iana_id, &tkm_id))
+	{
+		f[i] = PLUGIN_PROVIDE(DH, *iana_id);
+		i++;
+	}
+	enumerator->destroy(enumerator);
+
+	lib->plugins->add_static_features(lib->plugins, "tkm-dh", f, countof(f), TRUE);
+
+	if (count > 0)
+	{
+		group_map = map;
+	}
+	else
+	{
+		map->destroy(map);
+	}
+
+	return count;
+}
+
+/*
+ * Described in header.
+ */
+void destroy_dh_mapping()
+{
+	enumerator_t *enumerator;
+	char *key, *value;
+
+	if (group_map)
+	{
+		enumerator = group_map->create_enumerator(group_map);
+		while (enumerator->enumerate(enumerator, &key, &value))
+		{
+			free(key);
+			free(value);
+		}
+		enumerator->destroy(enumerator);
+		group_map->destroy(group_map);
+	}
+}
+
 /*
  * Described in header.
  */
@@ -109,6 +201,11 @@ tkm_diffie_hellman_t *tkm_diffie_hellman_create(diffie_hellman_group_t group)
 {
 	private_tkm_diffie_hellman_t *this;
 
+	if (!group_map)
+	{
+		return NULL;
+	}
+
 	INIT(this,
 		.public = {
 			.dh = {
@@ -130,7 +227,14 @@ tkm_diffie_hellman_t *tkm_diffie_hellman_create(diffie_hellman_group_t group)
 		return NULL;
 	}
 
-	if (ike_dh_create(this->context_id, group, &this->pubvalue) != TKM_OK)
+	u_int64_t *dha_id = group_map->get(group_map, &group);
+	if (!dha_id)
+	{
+		free(this);
+		return NULL;
+	}
+
+	if (ike_dh_create(this->context_id, *dha_id, &this->pubvalue) != TKM_OK)
 	{
 		free(this);
 		return NULL;

src/charon-tkm/src/tkm/tkm_diffie_hellman.h

@@ -46,6 +46,19 @@ struct tkm_diffie_hellman_t {
 
 };
 
+/**
+ * Loads IANA DH group identifier to TKM id mapping from config and registers
+ * the corresponding DH features.
+ *
+ * @return          number of registered mappings
+ */
+int register_dh_mapping();
+
+/**
+ * Destroy IANA DH group identifier to TKM id mapping.
+ */
+void destroy_dh_mapping();
+
 /**
  * Creates a new tkm_diffie_hellman_t object.
  *

src/charon-tkm/tests/diffie_hellman_tests.c

@@ -14,6 +14,7 @@
  * for more details.
  */
 
+#include <daemon.h>
 #include <tests/test_suite.h>
 
 #include "tkm_diffie_hellman.h"

src/charon-tkm/tests/tests.c

@@ -60,15 +60,18 @@ static bool test_runner_init(bool init)
 		static plugin_feature_t features[] = {
 			PLUGIN_REGISTER(NONCE_GEN, tkm_nonceg_create),
 				PLUGIN_PROVIDE(NONCE_GEN),
-			PLUGIN_REGISTER(DH, tkm_diffie_hellman_create),
-				PLUGIN_PROVIDE(DH, MODP_3072_BIT),
-				PLUGIN_PROVIDE(DH, MODP_4096_BIT),
 			PLUGIN_CALLBACK(kernel_ipsec_register, tkm_kernel_ipsec_create),
 				PLUGIN_PROVIDE(CUSTOM, "kernel-ipsec"),
 		};
 		lib->plugins->add_static_features(lib->plugins, "tkm-tests", features,
 										  countof(features), TRUE);
 
+		lib->settings->set_int(lib->settings, "%s.dh_mapping.%d", 1,
+							   charon->name, MODP_3072_BIT);
+		lib->settings->set_int(lib->settings, "%s.dh_mapping.%d", 2,
+							   charon->name, MODP_4096_BIT);
+		register_dh_mapping();
+
 		plugin_loader_add_plugindirs(BUILDDIR "/src/libstrongswan/plugins",
 									 PLUGINS);
 		plugin_loader_add_plugindirs(BUILDDIR "/src/libhydra/plugins",
@@ -90,6 +93,7 @@ static bool test_runner_init(bool init)
 		result = FALSE;
 	}
 
+	destroy_dh_mapping();
 	libcharon_deinit();
 	libhydra_deinit();
 	return result;