global: do not allow compiler to reorder is_valid or is_dead

Suggested-by: Jann Horn <jann@thejh.net>

4 files changed, 17 insertions, 14 deletions

diff --git a/src/noise.c b/src/noise.c
index 4160fc0..d0a337a 100644
--- a/src/noise.c
+++ b/src/noise.c
@@ -775,8 +775,8 @@ bool wg_noise_handshake_begin_session(struct noise_handshake *handshake,
 
 	handshake_zero(handshake);
 	rcu_read_lock_bh();
-	if (likely(!container_of(handshake, struct wg_peer,
-				 handshake)->is_dead)) {
+	if (likely(!READ_ONCE(container_of(handshake, struct wg_peer,
+					   handshake)->is_dead))) {
 		add_new_keypair(keypairs, new_keypair);
 		net_dbg_ratelimited("%s: Keypair %llu created for peer %llu\n",
 				    handshake->entry.peer->device->dev->name,
diff --git a/src/receive.c b/src/receive.c
index 33a60b7..d5bce92 100644
--- a/src/receive.c
+++ b/src/receive.c
@@ -231,7 +231,7 @@ static void keep_key_fresh(struct wg_peer *peer)
 
 	rcu_read_lock_bh();
 	keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
-	if (likely(keypair && keypair->sending.is_valid) &&
+	if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
 	    keypair->i_am_the_initiator &&
 	    unlikely(wg_birthdate_has_expired(keypair->sending.birthdate,
 			REJECT_AFTER_TIME - KEEPALIVE_TIMEOUT - REKEY_TIMEOUT)))
@@ -255,10 +255,10 @@ static bool decrypt_packet(struct sk_buff *skb, struct noise_symmetric_key *key,
 	if (unlikely(!key))
 		return false;
 
-	if (unlikely(!key->is_valid ||
+	if (unlikely(!READ_ONCE(key->is_valid) ||
 		  wg_birthdate_has_expired(key->birthdate, REJECT_AFTER_TIME) ||
 		  key->counter.receive.counter >= REJECT_AFTER_MESSAGES)) {
-		key->is_valid = false;
+		WRITE_ONCE(key->is_valid, false);
 		return false;
 	}
 
@@ -534,7 +534,7 @@ static void wg_packet_consume_data(struct wg_device *wg, struct sk_buff *skb)
 	if (unlikely(!wg_noise_keypair_get(PACKET_CB(skb)->keypair)))
 		goto err_keypair;
 
-	if (unlikely(peer->is_dead))
+	if (unlikely(READ_ONCE(peer->is_dead)))
 		goto err;
 
 	ret = wg_queue_enqueue_per_device_and_peer(&wg->decrypt_queue,
diff --git a/src/send.c b/src/send.c
index b7f8283..1e97aa1 100644
--- a/src/send.c
+++ b/src/send.c
@@ -65,7 +65,8 @@ void wg_packet_send_queued_handshake_initiation(struct wg_peer *peer,
 	 * necessary:
 	 */
 	if (!wg_birthdate_has_expired(atomic64_read(&peer->last_sent_handshake),
-				      REKEY_TIMEOUT) || unlikely(peer->is_dead))
+				      REKEY_TIMEOUT) ||
+			unlikely(READ_ONCE(peer->is_dead)))
 		goto out;
 
 	wg_peer_get(peer);
@@ -128,7 +129,7 @@ static void keep_key_fresh(struct wg_peer *peer)
 
 	rcu_read_lock_bh();
 	keypair = rcu_dereference_bh(peer->keypairs.current_keypair);
-	if (likely(keypair && keypair->sending.is_valid) &&
+	if (likely(keypair && READ_ONCE(keypair->sending.is_valid)) &&
 	    (unlikely(atomic64_read(&keypair->sending.counter.counter) >
 		      REKEY_AFTER_MESSAGES) ||
 	     (keypair->i_am_the_initiator &&
@@ -327,7 +328,7 @@ static void wg_packet_create_data(struct sk_buff *first)
 	int ret = -EINVAL;
 
 	rcu_read_lock_bh();
-	if (unlikely(peer->is_dead))
+	if (unlikely(READ_ONCE(peer->is_dead)))
 		goto err;
 
 	ret = wg_queue_enqueue_per_device_and_peer(&wg->encrypt_queue,
@@ -369,7 +370,7 @@ void wg_packet_send_staged_packets(struct wg_peer *peer)
 	if (unlikely(!keypair))
 		goto out_nokey;
 	key = &keypair->sending;
-	if (unlikely(!key->is_valid))
+	if (unlikely(!READ_ONCE(key->is_valid)))
 		goto out_nokey;
 	if (unlikely(wg_birthdate_has_expired(key->birthdate,
 					      REJECT_AFTER_TIME)))
@@ -398,7 +399,7 @@ void wg_packet_send_staged_packets(struct wg_peer *peer)
 	return;
 
 out_invalid:
-	key->is_valid = false;
+	WRITE_ONCE(key->is_valid, false);
 out_nokey:
 	wg_noise_keypair_put(keypair, false);
 
diff --git a/src/timers.c b/src/timers.c
index 0312bd8..22eb1ee 100644
--- a/src/timers.c
+++ b/src/timers.c
@@ -39,7 +39,8 @@ static inline void mod_peer_timer(struct wg_peer *peer,
 				  unsigned long expires)
 {
 	rcu_read_lock_bh();
-	if (likely(netif_running(peer->device->dev) && !peer->is_dead))
+	if (likely(netif_running(peer->device->dev) &&
+		   !READ_ONCE(peer->is_dead)))
 		mod_timer(timer, expires);
 	rcu_read_unlock_bh();
 }
@@ -48,7 +49,8 @@ static inline void del_peer_timer(struct wg_peer *peer,
 				  struct timer_list *timer)
 {
 	rcu_read_lock_bh();
-	if (likely(netif_running(peer->device->dev) && !peer->is_dead))
+	if (likely(netif_running(peer->device->dev) &&
+		   !READ_ONCE(peer->is_dead)))
 		del_timer(timer);
 	rcu_read_unlock_bh();
 }
@@ -136,7 +138,7 @@ static void wg_expired_zero_key_material(struct timer_list *timer)
 		return;
 
 	rcu_read_lock_bh();
-	if (!peer->is_dead) {
+	if (!READ_ONCE(peer->is_dead)) {
 		 /* Should take our reference. */
 		if (!queue_work(peer->device->handshake_send_wq,
 				&peer->clear_peer_work))