244 lines
8 KiB
C
244 lines
8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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*/
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#include "timers.h"
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#include "device.h"
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#include "peer.h"
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#include "queueing.h"
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#include "socket.h"
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/*
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* - Timer for retransmitting the handshake if we don't hear back after
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* `REKEY_TIMEOUT + jitter` ms.
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*
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* - Timer for sending empty packet if we have received a packet but after have
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* not sent one for `KEEPALIVE_TIMEOUT` ms.
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*
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* - Timer for initiating new handshake if we have sent a packet but after have
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* not received one (even empty) for `(KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) +
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* jitter` ms.
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*
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* - Timer for zeroing out all ephemeral keys after `(REJECT_AFTER_TIME * 3)` ms
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* if no new keys have been received.
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*
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* - Timer for, if enabled, sending an empty authenticated packet every user-
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* specified seconds.
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*/
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static inline void mod_peer_timer(struct wg_peer *peer,
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struct timer_list *timer,
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unsigned long expires)
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{
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rcu_read_lock_bh();
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if (likely(netif_running(peer->device->dev) &&
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!READ_ONCE(peer->is_dead)))
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mod_timer(timer, expires);
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rcu_read_unlock_bh();
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}
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static void wg_expired_retransmit_handshake(struct timer_list *timer)
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{
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struct wg_peer *peer = from_timer(peer, timer,
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timer_retransmit_handshake);
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if (peer->timer_handshake_attempts > MAX_TIMER_HANDSHAKES) {
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pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d attempts, giving up\n",
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peer->device->dev->name, peer->internal_id,
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&peer->endpoint.addr, MAX_TIMER_HANDSHAKES + 2);
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del_timer(&peer->timer_send_keepalive);
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/* We drop all packets without a keypair and don't try again,
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* if we try unsuccessfully for too long to make a handshake.
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*/
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wg_packet_purge_staged_packets(peer);
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/* We set a timer for destroying any residue that might be left
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* of a partial exchange.
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*/
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if (!timer_pending(&peer->timer_zero_key_material))
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mod_peer_timer(peer, &peer->timer_zero_key_material,
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jiffies + REJECT_AFTER_TIME * 3 * HZ);
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} else {
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++peer->timer_handshake_attempts;
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pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d seconds, retrying (try %d)\n",
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peer->device->dev->name, peer->internal_id,
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&peer->endpoint.addr, REKEY_TIMEOUT,
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peer->timer_handshake_attempts + 1);
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/* We clear the endpoint address src address, in case this is
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* the cause of trouble.
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*/
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wg_socket_clear_peer_endpoint_src(peer);
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wg_packet_send_queued_handshake_initiation(peer, true);
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}
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}
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static void wg_expired_send_keepalive(struct timer_list *timer)
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{
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struct wg_peer *peer = from_timer(peer, timer, timer_send_keepalive);
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wg_packet_send_keepalive(peer);
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if (peer->timer_need_another_keepalive) {
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peer->timer_need_another_keepalive = false;
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mod_peer_timer(peer, &peer->timer_send_keepalive,
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jiffies + KEEPALIVE_TIMEOUT * HZ);
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}
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}
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static void wg_expired_new_handshake(struct timer_list *timer)
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{
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struct wg_peer *peer = from_timer(peer, timer, timer_new_handshake);
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pr_debug("%s: Retrying handshake with peer %llu (%pISpfsc) because we stopped hearing back after %d seconds\n",
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peer->device->dev->name, peer->internal_id,
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&peer->endpoint.addr, KEEPALIVE_TIMEOUT + REKEY_TIMEOUT);
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/* We clear the endpoint address src address, in case this is the cause
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* of trouble.
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*/
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wg_socket_clear_peer_endpoint_src(peer);
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wg_packet_send_queued_handshake_initiation(peer, false);
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}
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static void wg_expired_zero_key_material(struct timer_list *timer)
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{
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struct wg_peer *peer = from_timer(peer, timer, timer_zero_key_material);
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rcu_read_lock_bh();
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if (!READ_ONCE(peer->is_dead)) {
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wg_peer_get(peer);
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if (!queue_work(peer->device->handshake_send_wq,
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&peer->clear_peer_work))
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/* If the work was already on the queue, we want to drop
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* the extra reference.
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*/
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wg_peer_put(peer);
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}
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rcu_read_unlock_bh();
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}
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static void wg_queued_expired_zero_key_material(struct work_struct *work)
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{
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struct wg_peer *peer = container_of(work, struct wg_peer,
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clear_peer_work);
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pr_debug("%s: Zeroing out all keys for peer %llu (%pISpfsc), since we haven't received a new one in %d seconds\n",
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peer->device->dev->name, peer->internal_id,
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&peer->endpoint.addr, REJECT_AFTER_TIME * 3);
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wg_noise_handshake_clear(&peer->handshake);
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wg_noise_keypairs_clear(&peer->keypairs);
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wg_peer_put(peer);
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}
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static void wg_expired_send_persistent_keepalive(struct timer_list *timer)
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{
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struct wg_peer *peer = from_timer(peer, timer,
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timer_persistent_keepalive);
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if (likely(peer->persistent_keepalive_interval))
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wg_packet_send_keepalive(peer);
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}
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/* Should be called after an authenticated data packet is sent. */
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void wg_timers_data_sent(struct wg_peer *peer)
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{
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if (!timer_pending(&peer->timer_new_handshake))
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mod_peer_timer(peer, &peer->timer_new_handshake,
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jiffies + (KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) * HZ +
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prandom_u32_max(REKEY_TIMEOUT_JITTER_MAX_JIFFIES));
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}
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/* Should be called after an authenticated data packet is received. */
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void wg_timers_data_received(struct wg_peer *peer)
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{
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if (likely(netif_running(peer->device->dev))) {
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if (!timer_pending(&peer->timer_send_keepalive))
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mod_peer_timer(peer, &peer->timer_send_keepalive,
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jiffies + KEEPALIVE_TIMEOUT * HZ);
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else
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peer->timer_need_another_keepalive = true;
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}
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}
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/* Should be called after any type of authenticated packet is sent, whether
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* keepalive, data, or handshake.
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*/
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void wg_timers_any_authenticated_packet_sent(struct wg_peer *peer)
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{
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del_timer(&peer->timer_send_keepalive);
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}
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/* Should be called after any type of authenticated packet is received, whether
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* keepalive, data, or handshake.
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*/
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void wg_timers_any_authenticated_packet_received(struct wg_peer *peer)
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{
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del_timer(&peer->timer_new_handshake);
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}
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/* Should be called after a handshake initiation message is sent. */
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void wg_timers_handshake_initiated(struct wg_peer *peer)
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{
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mod_peer_timer(peer, &peer->timer_retransmit_handshake,
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jiffies + REKEY_TIMEOUT * HZ +
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prandom_u32_max(REKEY_TIMEOUT_JITTER_MAX_JIFFIES));
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}
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/* Should be called after a handshake response message is received and processed
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* or when getting key confirmation via the first data message.
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*/
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void wg_timers_handshake_complete(struct wg_peer *peer)
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{
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del_timer(&peer->timer_retransmit_handshake);
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peer->timer_handshake_attempts = 0;
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peer->sent_lastminute_handshake = false;
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ktime_get_real_ts64(&peer->walltime_last_handshake);
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}
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/* Should be called after an ephemeral key is created, which is before sending a
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* handshake response or after receiving a handshake response.
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*/
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void wg_timers_session_derived(struct wg_peer *peer)
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{
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mod_peer_timer(peer, &peer->timer_zero_key_material,
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jiffies + REJECT_AFTER_TIME * 3 * HZ);
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}
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/* Should be called before a packet with authentication, whether
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* keepalive, data, or handshakem is sent, or after one is received.
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*/
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void wg_timers_any_authenticated_packet_traversal(struct wg_peer *peer)
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{
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if (peer->persistent_keepalive_interval)
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mod_peer_timer(peer, &peer->timer_persistent_keepalive,
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jiffies + peer->persistent_keepalive_interval * HZ);
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}
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void wg_timers_init(struct wg_peer *peer)
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{
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timer_setup(&peer->timer_retransmit_handshake,
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wg_expired_retransmit_handshake, 0);
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timer_setup(&peer->timer_send_keepalive, wg_expired_send_keepalive, 0);
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timer_setup(&peer->timer_new_handshake, wg_expired_new_handshake, 0);
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timer_setup(&peer->timer_zero_key_material,
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wg_expired_zero_key_material, 0);
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timer_setup(&peer->timer_persistent_keepalive,
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wg_expired_send_persistent_keepalive, 0);
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INIT_WORK(&peer->clear_peer_work, wg_queued_expired_zero_key_material);
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peer->timer_handshake_attempts = 0;
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peer->sent_lastminute_handshake = false;
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peer->timer_need_another_keepalive = false;
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}
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void wg_timers_stop(struct wg_peer *peer)
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{
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del_timer_sync(&peer->timer_retransmit_handshake);
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del_timer_sync(&peer->timer_send_keepalive);
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del_timer_sync(&peer->timer_new_handshake);
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del_timer_sync(&peer->timer_zero_key_material);
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del_timer_sync(&peer->timer_persistent_keepalive);
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flush_work(&peer->clear_peer_work);
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}
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