Initial commit

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

1 files changed, 168 insertions, 0 deletions

diff --git a/src/timers.c b/src/timers.c
new file mode 100644
index 0000000..47d7854
--- /dev/null
+++ b/src/timers.c
@@ -0,0 +1,168 @@
+/* Copyright 2015-2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
+
+#include "wireguard.h"
+#include "timers.h"
+#include "packets.h"
+#include "device.h"
+
+enum {
+	KEEPALIVE = 10 * HZ,
+	MAX_TIMER_HANDSHAKES = (90 * HZ) / REKEY_TIMEOUT
+};
+
+/*
+ * Timer for retransmitting the handshake if we don't hear back after `REKEY_TIMEOUT` ms
+ * Timer for sending empty packet if we have received a packet but after have not sent one for `KEEPALIVE` ms
+ * Timer for initiating new handshake if we have sent a packet but after have not received one (even empty) for `(KEEPALIVE + REKEY_TIMEOUT)` ms
+ * Timer for zeroing out all ephemeral keys after `(REJECT_AFTER_TIME * 3)` ms if no new keys have been received
+ */
+
+static void expired_retransmit_handshake(unsigned long ptr)
+{
+	struct wireguard_peer *peer = (struct wireguard_peer *)ptr;
+
+	pr_debug("Handshake for peer %Lu (%pISpfsc) did not complete after %d seconds, retrying\n", peer->internal_id, &peer->endpoint_addr, REKEY_TIMEOUT / HZ);
+	if (peer->timer_handshake_attempts > MAX_TIMER_HANDSHAKES) {
+		del_timer(&peer->timer_send_keepalive);
+		/* We remove all existing packets and don't try again,
+		 * if we try unsuccessfully for too long to make a handshake. */
+		skb_queue_purge(&peer->tx_packet_queue);
+		return;
+	}
+	packet_queue_send_handshake_initiation(peer);
+	++peer->timer_handshake_attempts;
+}
+
+static void expired_send_keepalive(unsigned long ptr)
+{
+	struct wireguard_peer *peer = (struct wireguard_peer *)ptr;
+
+	pr_debug("Sending keep alive packet to peer %Lu (%pISpfsc), since we received data, but haven't sent any for %d seconds\n", peer->internal_id, &peer->endpoint_addr, KEEPALIVE / HZ);
+	packet_send_keepalive(peer);
+	if (peer->timer_need_another_keepalive) {
+		peer->timer_need_another_keepalive = false;
+		mod_timer(&peer->timer_send_keepalive, jiffies + KEEPALIVE);
+	}
+}
+
+static void expired_new_handshake(unsigned long ptr)
+{
+	struct wireguard_peer *peer = (struct wireguard_peer *)ptr;
+
+	pr_debug("Retrying handshake with peer %Lu (%pISpfsc) because we stopped hearing back after %d seconds\n", peer->internal_id, &peer->endpoint_addr, (KEEPALIVE + REKEY_TIMEOUT) / HZ);
+	packet_queue_send_handshake_initiation(peer);
+}
+
+static void expired_kill_ephemerals(unsigned long ptr)
+{
+	struct wireguard_peer *peer = (struct wireguard_peer *)ptr;
+
+	rcu_read_lock();
+	peer = peer_get(peer);
+	rcu_read_unlock();
+	if (!peer)
+		return;
+
+	if (!queue_work(peer->device->workqueue, &peer->clear_peer_work))
+		peer_put(peer); /* If the work was already on the queue, we want to drop the extra reference */
+}
+static void queued_expired_kill_ephemerals(struct work_struct *work)
+{
+	struct wireguard_peer *peer = container_of(work, struct wireguard_peer, clear_peer_work);
+
+	pr_debug("Zeroing out all keys for peer %Lu (%pISpfsc), since we haven't received a new one in %d seconds\n", peer->internal_id, &peer->endpoint_addr, (REJECT_AFTER_TIME * 3) / HZ);
+	noise_handshake_clear(&peer->handshake);
+	noise_keypairs_clear(&peer->keypairs);
+	peer_put(peer);
+}
+
+void timers_data_sent(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_send_keepalive.data))
+		del_timer(&peer->timer_send_keepalive);
+
+	if (likely(peer->timer_new_handshake.data) && !timer_pending(&peer->timer_new_handshake))
+		mod_timer(&peer->timer_new_handshake, jiffies + KEEPALIVE + REKEY_TIMEOUT);
+}
+
+void timers_data_received(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_send_keepalive.data) && !timer_pending(&peer->timer_send_keepalive))
+		mod_timer(&peer->timer_send_keepalive, jiffies + KEEPALIVE);
+	else
+		peer->timer_need_another_keepalive = true;
+}
+
+void timers_any_authorized_packet_received(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_new_handshake.data))
+		del_timer(&peer->timer_new_handshake);
+}
+
+void timers_handshake_initiated(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_send_keepalive.data))
+		del_timer(&peer->timer_send_keepalive);
+	if (likely(peer->timer_retransmit_handshake.data))
+		mod_timer(&peer->timer_retransmit_handshake, jiffies + REKEY_TIMEOUT);
+}
+
+void timers_handshake_complete(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_retransmit_handshake.data))
+		del_timer(&peer->timer_retransmit_handshake);
+	peer->timer_handshake_attempts = 0;
+}
+
+void timers_ephemeral_key_created(struct wireguard_peer *peer)
+{
+	if (likely(peer->timer_kill_ephemerals.data))
+		mod_timer(&peer->timer_kill_ephemerals, jiffies + (REJECT_AFTER_TIME * 3));
+	do_gettimeofday(&peer->walltime_last_handshake);
+}
+
+void timers_init_peer(struct wireguard_peer *peer)
+{
+	init_timer(&peer->timer_retransmit_handshake);
+	peer->timer_retransmit_handshake.function = expired_retransmit_handshake;
+	peer->timer_retransmit_handshake.data = (unsigned long)peer;
+
+	init_timer(&peer->timer_send_keepalive);
+	peer->timer_send_keepalive.function = expired_send_keepalive;
+	peer->timer_send_keepalive.data = (unsigned long)peer;
+
+	init_timer(&peer->timer_new_handshake);
+	peer->timer_new_handshake.function = expired_new_handshake;
+	peer->timer_new_handshake.data = (unsigned long)peer;
+
+	init_timer(&peer->timer_kill_ephemerals);
+	peer->timer_kill_ephemerals.function = expired_kill_ephemerals;
+	peer->timer_kill_ephemerals.data = (unsigned long)peer;
+
+	INIT_WORK(&peer->clear_peer_work, queued_expired_kill_ephemerals);
+}
+
+void timers_uninit_peer(struct wireguard_peer *peer)
+{
+	if (peer->timer_retransmit_handshake.data) {
+		del_timer(&peer->timer_retransmit_handshake);
+		peer->timer_retransmit_handshake.data = 0;
+	}
+	if (peer->timer_send_keepalive.data) {
+		del_timer(&peer->timer_send_keepalive);
+		peer->timer_send_keepalive.data = 0;
+	}
+	if (peer->timer_new_handshake.data) {
+		del_timer(&peer->timer_new_handshake);
+		peer->timer_new_handshake.data = 0;
+	}
+	if (peer->timer_kill_ephemerals.data) {
+		del_timer(&peer->timer_kill_ephemerals);
+		peer->timer_kill_ephemerals.data = 0;
+	}
+}
+void timers_uninit_peer_wait(struct wireguard_peer *peer)
+{
+	timers_uninit_peer(peer);
+	flush_work(&peer->clear_peer_work);
+}