RADIUS DAS: Validate Event-Timestamp

DAS will now validate Event-Timestamp value to be within an acceptable
time window (300 seconds by default; can be set using
radius_das_time_window parameter). In addition, Event-Timestamp can be
required in Disconnect-Request and CoA-Request messages with
radius_das_require_event_timestamp=1.

Signed-hostap: Jouni Malinen <j@w1.fi>

hostapd/config_file.c

@@ -1693,6 +1693,11 @@ static int hostapd_config_fill(struct hostapd_config *conf,
 					   "DAS client", line);
 				errors++;
 			}
+		} else if (os_strcmp(buf, "radius_das_time_window") == 0) {
+			bss->radius_das_time_window = atoi(pos);
+		} else if (os_strcmp(buf, "radius_das_require_event_timestamp")
+			   == 0) {
+			bss->radius_das_require_event_timestamp = atoi(pos);
 #endif /* CONFIG_NO_RADIUS */
 		} else if (os_strcmp(buf, "auth_algs") == 0) {
 			bss->auth_algs = atoi(pos);

hostapd/hostapd.conf

@@ -708,6 +708,12 @@ own_ip_addr=127.0.0.1
 #
 # DAS client (the host that can send Disconnect/CoA requests) and shared secret
 #radius_das_client=192.168.1.123 shared secret here
+#
+# DAS Event-Timestamp time window in seconds
+#radius_das_time_window=300
+#
+# DAS require Event-Timestamp
+#radius_das_require_event_timestamp=1
 
 ##### RADIUS authentication server configuration ##############################
 

src/ap/ap_config.c

@@ -87,6 +87,8 @@ void hostapd_config_defaults_bss(struct hostapd_bss_config *bss)
 #ifdef CONFIG_IEEE80211R
 	bss->ft_over_ds = 1;
 #endif /* CONFIG_IEEE80211R */
+
+	bss->radius_das_time_window = 300;
 }
 
 

src/ap/ap_config.h

@@ -187,6 +187,8 @@ struct hostapd_bss_config {
 	struct hostapd_radius_attr *radius_auth_req_attr;
 	struct hostapd_radius_attr *radius_acct_req_attr;
 	int radius_das_port;
+	unsigned int radius_das_time_window;
+	int radius_das_require_event_timestamp;
 	struct hostapd_ip_addr radius_das_client_addr;
 	u8 *radius_das_shared_secret;
 	size_t radius_das_shared_secret_len;

src/ap/hostapd.c

@@ -639,6 +639,9 @@ static int hostapd_setup_bss(struct hostapd_data *hapd, int first)
 		das_conf.shared_secret_len =
 			hapd->conf->radius_das_shared_secret_len;
 		das_conf.client_addr = &hapd->conf->radius_das_client_addr;
+		das_conf.time_window = hapd->conf->radius_das_time_window;
+		das_conf.require_event_timestamp =
+			hapd->conf->radius_das_require_event_timestamp;
 		hapd->radius_das = radius_das_init(&das_conf);
 		if (hapd->radius_das == NULL) {
 			wpa_printf(MSG_ERROR, "RADIUS DAS initialization "

src/radius/radius_das.c

@@ -24,6 +24,8 @@ struct radius_das_data {
 	u8 *shared_secret;
 	size_t shared_secret_len;
 	struct hostapd_ip_addr client_addr;
+	unsigned int time_window;
+	int require_event_timestamp;
 };
 
 
@@ -45,6 +47,8 @@ static void radius_das_receive(int sock, void *eloop_ctx, void *sock_ctx)
 	struct radius_msg *msg, *reply = NULL;
 	struct radius_hdr *hdr;
 	struct wpabuf *rbuf;
+	u32 val;
+	int res;
 
 	fromlen = sizeof(from);
 	len = recvfrom(sock, buf, sizeof(buf), 0,
@@ -81,6 +85,27 @@ static void radius_das_receive(int sock, void *eloop_ctx, void *sock_ctx)
 		goto fail;
 	}
 
+	res = radius_msg_get_attr(msg, RADIUS_ATTR_EVENT_TIMESTAMP,
+				  (u8 *) &val, 4);
+	if (res == 4) {
+		u32 timestamp = ntohl(val);
+		struct os_time now;
+
+		os_get_time(&now);
+		if (abs(now.sec - timestamp) > das->time_window) {
+			wpa_printf(MSG_DEBUG, "DAS: Unacceptable "
+				   "Event-Timestamp (%u; local time %u) in "
+				   "packet from %s:%d - drop",
+				   timestamp, (unsigned int) now.sec,
+				   abuf, from_port);
+			goto fail;
+		}
+	} else if (das->require_event_timestamp) {
+		wpa_printf(MSG_DEBUG, "DAS: Missing Event-Timestamp in packet "
+			   "from %s:%d - drop", abuf, from_port);
+		goto fail;
+	}
+
 	hdr = radius_msg_get_hdr(msg);
 
 	switch (hdr->code) {
@@ -110,8 +135,6 @@ static void radius_das_receive(int sock, void *eloop_ctx, void *sock_ctx)
 	}
 
 	if (reply) {
-		int res;
-
 		wpa_printf(MSG_DEBUG, "DAS: Reply to %s:%d", abuf, from_port);
 
 		if (radius_msg_finish_das_resp(reply, das->shared_secret,
@@ -177,6 +200,9 @@ radius_das_init(struct radius_das_conf *conf)
 	if (das == NULL)
 		return NULL;
 
+	das->time_window = conf->time_window;
+	das->require_event_timestamp = conf->require_event_timestamp;
+
 	os_memcpy(&das->client_addr, conf->client_addr,
 		  sizeof(das->client_addr));
 

src/radius/radius_das.h

@@ -16,6 +16,8 @@ struct radius_das_conf {
 	const u8 *shared_secret;
 	size_t shared_secret_len;
 	const struct hostapd_ip_addr *client_addr;
+	unsigned int time_window;
+	int require_event_timestamp;
 };
 
 struct radius_das_data *