kernel-netlink: Use total retransmit timeout as acquire timeout

By using the total retransmit timeout, modifications of timeout settings
automatically reflect on the value of xfrm_acq_expires.  If set, the
value of xfrm_acq_expires configured by the user takes precedence over
the calculated value.

src/libcharon/plugins/kernel_netlink/kernel_netlink_ipsec.c

@@ -78,9 +78,6 @@
 /** Base priority for installed policies */
 #define PRIO_BASE 200000
 
-/** Default lifetime of an acquire XFRM state (in seconds) */
-#define DEFAULT_ACQUIRE_LIFETIME 165
-
 /**
  * Map the limit for bytes and packets to XFRM_INF by default
  */
@@ -3231,7 +3228,6 @@ kernel_netlink_ipsec_t *kernel_netlink_ipsec_create()
 {
 	private_kernel_netlink_ipsec_t *this;
 	bool register_for_events = TRUE;
-	FILE *f;
 
 	INIT(this,
 		.public = {
@@ -3276,15 +3272,6 @@ kernel_netlink_ipsec_t *kernel_netlink_ipsec_create()
 		register_for_events = FALSE;
 	}
 
-	f = fopen("/proc/sys/net/core/xfrm_acq_expires", "w");
-	if (f)
-	{
-		fprintf(f, "%u", lib->settings->get_int(lib->settings,
-								"%s.plugins.kernel-netlink.xfrm_acq_expires",
-								DEFAULT_ACQUIRE_LIFETIME, lib->ns));
-		fclose(f);
-	}
-
 	this->socket_xfrm = netlink_socket_create(NETLINK_XFRM, xfrm_msg_names,
 				lib->settings->get_bool(lib->settings,
 					"%s.plugins.kernel-netlink.parallel_xfrm", FALSE, lib->ns));