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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "timers.h"
#include "device.h"
#include "peer.h"
#include "queueing.h"
#include "socket.h"
/*
* - Timer for retransmitting the handshake if we don't hear back after
* `REKEY_TIMEOUT + jitter` ms.
*
* - Timer for sending empty packet if we have received a packet but after have
* not sent one for `KEEPALIVE_TIMEOUT` ms.
*
* - Timer for initiating new handshake if we have sent a packet but after have
* not received one (even empty) for `(KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) +
* jitter` ms.
*
* - Timer for zeroing out all ephemeral keys after `(REJECT_AFTER_TIME * 3)` ms
* if no new keys have been received.
*
* - Timer for, if enabled, sending an empty authenticated packet every user-
* specified seconds.
*/
static inline void mod_peer_timer(struct wg_peer *peer,
struct timer_list *timer,
unsigned long expires)
{
rcu_read_lock_bh();
if (likely(netif_running(peer->device->dev) &&
!READ_ONCE(peer->is_dead)))
mod_timer(timer, expires);
rcu_read_unlock_bh();
}
static void wg_expired_retransmit_handshake(struct timer_list *timer)
{
struct wg_peer *peer = from_timer(peer, timer,
timer_retransmit_handshake);
if (peer->timer_handshake_attempts > MAX_TIMER_HANDSHAKES) {
pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d attempts, giving up\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr, MAX_TIMER_HANDSHAKES + 2);
del_timer(&peer->timer_send_keepalive);
/* We drop all packets without a keypair and don't try again,
* if we try unsuccessfully for too long to make a handshake.
*/
wg_packet_purge_staged_packets(peer);
/* We set a timer for destroying any residue that might be left
* of a partial exchange.
*/
if (!timer_pending(&peer->timer_zero_key_material))
mod_peer_timer(peer, &peer->timer_zero_key_material,
jiffies + REJECT_AFTER_TIME * 3 * HZ);
} else {
++peer->timer_handshake_attempts;
pr_debug("%s: Handshake for peer %llu (%pISpfsc) did not complete after %d seconds, retrying (try %d)\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr, REKEY_TIMEOUT,
peer->timer_handshake_attempts + 1);
/* We clear the endpoint address src address, in case this is
* the cause of trouble.
*/
wg_socket_clear_peer_endpoint_src(peer);
wg_packet_send_queued_handshake_initiation(peer, true);
}
}
static void wg_expired_send_keepalive(struct timer_list *timer)
{
struct wg_peer *peer = from_timer(peer, timer, timer_send_keepalive);
wg_packet_send_keepalive(peer);
if (peer->timer_need_another_keepalive) {
peer->timer_need_another_keepalive = false;
mod_peer_timer(peer, &peer->timer_send_keepalive,
jiffies + KEEPALIVE_TIMEOUT * HZ);
}
}
static void wg_expired_new_handshake(struct timer_list *timer)
{
struct wg_peer *peer = from_timer(peer, timer, timer_new_handshake);
pr_debug("%s: Retrying handshake with peer %llu (%pISpfsc) because we stopped hearing back after %d seconds\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr, KEEPALIVE_TIMEOUT + REKEY_TIMEOUT);
/* We clear the endpoint address src address, in case this is the cause
* of trouble.
*/
wg_socket_clear_peer_endpoint_src(peer);
wg_packet_send_queued_handshake_initiation(peer, false);
}
static void wg_expired_zero_key_material(struct timer_list *timer)
{
struct wg_peer *peer = from_timer(peer, timer, timer_zero_key_material);
rcu_read_lock_bh();
if (!READ_ONCE(peer->is_dead)) {
wg_peer_get(peer);
if (!queue_work(peer->device->handshake_send_wq,
&peer->clear_peer_work))
/* If the work was already on the queue, we want to drop
* the extra reference.
*/
wg_peer_put(peer);
}
rcu_read_unlock_bh();
}
static void wg_queued_expired_zero_key_material(struct work_struct *work)
{
struct wg_peer *peer = container_of(work, struct wg_peer,
clear_peer_work);
pr_debug("%s: Zeroing out all keys for peer %llu (%pISpfsc), since we haven't received a new one in %d seconds\n",
peer->device->dev->name, peer->internal_id,
&peer->endpoint.addr, REJECT_AFTER_TIME * 3);
wg_noise_handshake_clear(&peer->handshake);
wg_noise_keypairs_clear(&peer->keypairs);
wg_peer_put(peer);
}
static void wg_expired_send_persistent_keepalive(struct timer_list *timer)
{
struct wg_peer *peer = from_timer(peer, timer,
timer_persistent_keepalive);
if (likely(peer->persistent_keepalive_interval))
wg_packet_send_keepalive(peer);
}
/* Should be called after an authenticated data packet is sent. */
void wg_timers_data_sent(struct wg_peer *peer)
{
if (!timer_pending(&peer->timer_new_handshake))
mod_peer_timer(peer, &peer->timer_new_handshake,
jiffies + (KEEPALIVE_TIMEOUT + REKEY_TIMEOUT) * HZ +
get_random_u32_below(REKEY_TIMEOUT_JITTER_MAX_JIFFIES));
}
/* Should be called after an authenticated data packet is received. */
void wg_timers_data_received(struct wg_peer *peer)
{
if (likely(netif_running(peer->device->dev))) {
if (!timer_pending(&peer->timer_send_keepalive))
mod_peer_timer(peer, &peer->timer_send_keepalive,
jiffies + KEEPALIVE_TIMEOUT * HZ);
else
peer->timer_need_another_keepalive = true;
}
}
/* Should be called after any type of authenticated packet is sent, whether
* keepalive, data, or handshake.
*/
void wg_timers_any_authenticated_packet_sent(struct wg_peer *peer)
{
del_timer(&peer->timer_send_keepalive);
}
/* Should be called after any type of authenticated packet is received, whether
* keepalive, data, or handshake.
*/
void wg_timers_any_authenticated_packet_received(struct wg_peer *peer)
{
del_timer(&peer->timer_new_handshake);
}
/* Should be called after a handshake initiation message is sent. */
void wg_timers_handshake_initiated(struct wg_peer *peer)
{
mod_peer_timer(peer, &peer->timer_retransmit_handshake,
jiffies + REKEY_TIMEOUT * HZ +
get_random_u32_below(REKEY_TIMEOUT_JITTER_MAX_JIFFIES));
}
/* Should be called after a handshake response message is received and processed
* or when getting key confirmation via the first data message.
*/
void wg_timers_handshake_complete(struct wg_peer *peer)
{
del_timer(&peer->timer_retransmit_handshake);
peer->timer_handshake_attempts = 0;
peer->sent_lastminute_handshake = false;
ktime_get_real_ts64(&peer->walltime_last_handshake);
}
/* Should be called after an ephemeral key is created, which is before sending a
* handshake response or after receiving a handshake response.
*/
void wg_timers_session_derived(struct wg_peer *peer)
{
mod_peer_timer(peer, &peer->timer_zero_key_material,
jiffies + REJECT_AFTER_TIME * 3 * HZ);
}
/* Should be called before a packet with authentication, whether
* keepalive, data, or handshakem is sent, or after one is received.
*/
void wg_timers_any_authenticated_packet_traversal(struct wg_peer *peer)
{
if (peer->persistent_keepalive_interval)
mod_peer_timer(peer, &peer->timer_persistent_keepalive,
jiffies + peer->persistent_keepalive_interval * HZ);
}
void wg_timers_init(struct wg_peer *peer)
{
timer_setup(&peer->timer_retransmit_handshake,
wg_expired_retransmit_handshake, 0);
timer_setup(&peer->timer_send_keepalive, wg_expired_send_keepalive, 0);
timer_setup(&peer->timer_new_handshake, wg_expired_new_handshake, 0);
timer_setup(&peer->timer_zero_key_material,
wg_expired_zero_key_material, 0);
timer_setup(&peer->timer_persistent_keepalive,
wg_expired_send_persistent_keepalive, 0);
INIT_WORK(&peer->clear_peer_work, wg_queued_expired_zero_key_material);
peer->timer_handshake_attempts = 0;
peer->sent_lastminute_handshake = false;
peer->timer_need_another_keepalive = false;
}
void wg_timers_stop(struct wg_peer *peer)
{
del_timer_sync(&peer->timer_retransmit_handshake);
del_timer_sync(&peer->timer_send_keepalive);
del_timer_sync(&peer->timer_new_handshake);
del_timer_sync(&peer->timer_zero_key_material);
del_timer_sync(&peer->timer_persistent_keepalive);
flush_work(&peer->clear_peer_work);
}
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