handshake: add ref counting to handshake_state

This adds a ref count to the handshake state object (as well as
ref/unref APIs). Currently IWD is careful to ensure that netdev
holds the root reference to the handshake state. Other modules do
track it themselves, but ensure that it doesn't get referenced
after netdev frees it.

Future work related to PMKSA will require that station holds a
references to the handshake state, specifically for retry logic,
after netdev is done with it so we need a way to delay the free
until station is also done.

src/adhoc.c

@@ -94,13 +94,13 @@ static void adhoc_sta_free(void *data)
 		eapol_sm_free(sta->sm);
 
 	if (sta->hs_sta)
-		handshake_state_free(sta->hs_sta);
+		handshake_state_unref(sta->hs_sta);
 
 	if (sta->sm_a)
 		eapol_sm_free(sta->sm_a);
 
 	if (sta->hs_auth)
-		handshake_state_free(sta->hs_auth);
+		handshake_state_unref(sta->hs_auth);
 
 end:
 	l_free(sta);

src/ap.c

@@ -230,7 +230,7 @@ static void ap_stop_handshake(struct sta_state *sta)
 	}
 
 	if (sta->hs) {
-		handshake_state_free(sta->hs);
+		handshake_state_unref(sta->hs);
 		sta->hs = NULL;
 	}
 

src/handshake.c

@@ -103,7 +103,14 @@ void __handshake_set_install_ext_tk_func(handshake_install_ext_tk_func_t func)
 	install_ext_tk = func;
 }
 
-void handshake_state_free(struct handshake_state *s)
+struct handshake_state *handshake_state_ref(struct handshake_state *s)
+{
+	__sync_fetch_and_add(&s->refcount, 1);
+
+	return s;
+}
+
+void handshake_state_unref(struct handshake_state *s)
 {
 	__typeof__(s->free) destroy;
 
@@ -117,6 +124,9 @@ void handshake_state_free(struct handshake_state *s)
 		return;
 	}
 
+	if (__sync_sub_and_fetch(&s->refcount, 1))
+		return;
+
 	l_free(s->authenticator_ie);
 	l_free(s->supplicant_ie);
 	l_free(s->authenticator_rsnxe);

src/handshake.h

@@ -170,6 +170,8 @@ struct handshake_state {
 	bool in_event;
 
 	handshake_event_func_t event_func;
+
+	int refcount;
 };
 
 #define HSID(x) UNIQUE_ID(handshake_, x)
@@ -186,7 +188,7 @@ struct handshake_state {
 					##__VA_ARGS__);			\
 									\
 			if (!HSID(hs)->in_event) {			\
-				handshake_state_free(HSID(hs));		\
+				handshake_state_unref(HSID(hs));	\
 				HSID(freed) = true;			\
 			} else						\
 				HSID(hs)->in_event = false;		\
@@ -194,7 +196,8 @@ struct handshake_state {
 		HSID(freed);						\
 	})
 
-void handshake_state_free(struct handshake_state *s);
+struct handshake_state *handshake_state_ref(struct handshake_state *s);
+void handshake_state_unref(struct handshake_state *s);
 
 void handshake_state_set_supplicant_address(struct handshake_state *s,
 						const uint8_t *spa);
@@ -316,4 +319,4 @@ void handshake_util_build_gtk_kde(enum crypto_cipher cipher, const uint8_t *key,
 void handshake_util_build_igtk_kde(enum crypto_cipher cipher, const uint8_t *key,
 					unsigned int key_index, uint8_t *to);
 
-DEFINE_CLEANUP_FUNC(handshake_state_free);
+DEFINE_CLEANUP_FUNC(handshake_state_unref);

src/netdev.c

@@ -376,6 +376,7 @@ struct handshake_state *netdev_handshake_state_new(struct netdev *netdev)
 
 	nhs->super.ifindex = netdev->index;
 	nhs->super.free = netdev_handshake_state_free;
+	nhs->super.refcount = 1;
 
 	nhs->netdev = netdev;
 	/*
@@ -828,7 +829,7 @@ static void netdev_connect_free(struct netdev *netdev)
 	eapol_preauth_cancel(netdev->index);
 
 	if (netdev->handshake) {
-		handshake_state_free(netdev->handshake);
+		handshake_state_unref(netdev->handshake);
 		netdev->handshake = NULL;
 	}
 
@@ -4239,7 +4240,7 @@ int netdev_reassociate(struct netdev *netdev, const struct scan_bss *target_bss,
 		eapol_sm_free(old_sm);
 
 	if (old_hs)
-		handshake_state_free(old_hs);
+		handshake_state_unref(old_hs);
 
 	return 0;
 }

src/p2p.c

@@ -1497,7 +1497,7 @@ static void p2p_handshake_event(struct handshake_state *hs,
 static void p2p_try_connect_group(struct p2p_device *dev)
 {
 	struct scan_bss *bss = dev->conn_wsc_bss;
-	_auto_(handshake_state_free) struct handshake_state *hs = NULL;
+	_auto_(handshake_state_unref) struct handshake_state *hs = NULL;
 	struct iovec ie_iov[16];
 	int ie_num = 0;
 	int r;

src/station.c

@@ -1394,7 +1394,7 @@ static struct handshake_state *station_handshake_setup(struct station *station,
 	return hs;
 
 not_supported:
-	handshake_state_free(hs);
+	handshake_state_unref(hs);
 	return NULL;
 }
 
@@ -2484,7 +2484,7 @@ static void station_preauthenticate_cb(struct netdev *netdev,
 	}
 
 	if (station_transition_reassociate(station, bss, new_hs) < 0) {
-		handshake_state_free(new_hs);
+		handshake_state_unref(new_hs);
 		station_roam_failed(station);
 	}
 }
@@ -2687,7 +2687,7 @@ static bool station_try_next_transition(struct station *station,
 	}
 
 	if (station_transition_reassociate(station, bss, new_hs) < 0) {
-		handshake_state_free(new_hs);
+		handshake_state_unref(new_hs);
 		return false;
 	}
 
@@ -3734,7 +3734,7 @@ int __station_connect_network(struct station *station, struct network *network,
 				station_netdev_event,
 				station_connect_cb, station);
 	if (r < 0) {
-		handshake_state_free(hs);
+		handshake_state_unref(hs);
 		return r;
 	}
 

src/wsc.c

@@ -393,7 +393,7 @@ static int wsc_enrollee_connect(struct wsc_enrollee *wsce, struct scan_bss *bss,
 		return 0;
 
 error:
-	handshake_state_free(hs);
+	handshake_state_unref(hs);
 	return r;
 }