Implement CHILD SA key derivation using TKM

ESP SAs are created when adding CHILD SAs via the kernel ipsec
interface.

The encr_i key is used to transfer the context id of the parent IKE SA
from the keymat to the TKM kernel ipsec interface.

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

@@ -16,7 +16,11 @@
 
 #include <utils/debug.h>
 #include <plugins/kernel_netlink/kernel_netlink_ipsec.h>
+#include <tkm/constants.h>
+#include <tkm/client.h>
 
+#include "tkm_types.h"
+#include "tkm_keymat.h"
 #include "tkm_kernel_ipsec.h"
 
 typedef struct private_tkm_kernel_ipsec_t private_tkm_kernel_ipsec_t;
@@ -36,6 +40,11 @@ struct private_tkm_kernel_ipsec_t {
 	 */
 	kernel_netlink_ipsec_t *proxy;
 
+	/**
+	 * Local CHILD SA SPI.
+	 */
+	uint32_t esp_spi_loc;
+
 };
 
 METHOD(kernel_ipsec_t, get_spi, status_t,
@@ -62,11 +71,30 @@ METHOD(kernel_ipsec_t, add_sa, status_t,
 	u_int16_t cpi, bool encap, bool esn, bool inbound,
 	traffic_selector_t* src_ts, traffic_selector_t* dst_ts)
 {
-	DBG1(DBG_KNL, "adding child SA with SPI %.8x and reqid {%u}", ntohl(spi),
-		 reqid);
+	if (inbound && this->esp_spi_loc == 0)
+	{
+		DBG1(DBG_KNL, "store local child SA SPI for installation", ntohl(spi));
+		this->esp_spi_loc = spi;
+		this->proxy->interface.add_sa(&this->proxy->interface, src, dst, spi,
+									  protocol, reqid, mark, tfc, lifetime,
+									  enc_alg, enc_key, int_alg, int_key, mode,
+									  ipcomp, cpi, encap, esn, inbound, src_ts,
+									  dst_ts);
+		return SUCCESS;
+	}
+	const esa_info_t esa = *(esa_info_t *)(enc_key.ptr);
+	DBG1(DBG_KNL, "adding child SA (isa: %llu, esp_spi_loc: %x, esp_spi_rem:"
+		 " %x)", esa.isa_id, ntohl(this->esp_spi_loc), ntohl(spi));
+	if (ike_esa_create_first (1, esa.isa_id, 1, 1, ntohl(this->esp_spi_loc),
+							  ntohl(spi)) != TKM_OK)
+	{
+		DBG1(DBG_KNL, "child SA creation failed");
+		return FAILED;
+	}
+	this->esp_spi_loc = 0;
 	return this->proxy->interface.add_sa(&this->proxy->interface, src, dst, spi,
 										 protocol, reqid, mark, tfc, lifetime,
-										 enc_alg, enc_key, int_alg, int_key,
+										 enc_alg, esa.enc_key, int_alg, int_key,
 										 mode, ipcomp, cpi, encap, esn, inbound,
 										 src_ts, dst_ts);
 }
@@ -186,6 +214,7 @@ tkm_kernel_ipsec_t *tkm_kernel_ipsec_create()
 				.destroy = _destroy,
 			},
 		},
+		.esp_spi_loc = 0,
 		.proxy = kernel_netlink_ipsec_create(),
 	);
 

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

@@ -20,6 +20,7 @@
 #include <tkm/client.h>
 
 #include "tkm.h"
+#include "tkm_types.h"
 #include "tkm_utils.h"
 #include "tkm_diffie_hellman.h"
 #include "tkm_keymat.h"
@@ -291,8 +292,14 @@ METHOD(tkm_keymat_t, derive_child_keys, bool,
 	chunk_t *encr_r, chunk_t *integ_r)
 {
 	DBG1(DBG_CHD, "deriving child keys");
-	return this->proxy->derive_child_keys(this->proxy, proposal, dh, nonce_i,
-			nonce_r, encr_i, integ_i, encr_r, integ_r);
+	*encr_i = chunk_alloc(sizeof(esa_info_t));
+	(*(esa_info_t*)(encr_i->ptr)).isa_id = this->isa_ctx_id;
+	const bool result = this->proxy->derive_child_keys(this->proxy, proposal,
+													   dh, nonce_i, nonce_r,
+													   &(*(esa_info_t*)(encr_i->ptr)).enc_key,
+													   integ_i, encr_r,
+													   integ_r);
+	return result;
 }
 
 METHOD(keymat_t, get_aead, aead_t*,

src/charon-tkm/src/tkm/tkm_types.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2012 Reto Buerki
+ * Copyright (C) 2012 Adrian-Ken Rueegsegger
+ * 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.
+ */
+
+#ifndef TKM_TYPES_H_
+#define TKM_TYPES_H_
+
+typedef struct esa_info_t esa_info_t;
+
+struct esa_info_t {
+	isa_id_type isa_id;
+	chunk_t enc_key;
+};
+
+#endif /** TKM_TYPES_H_ */