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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include "peer.h"
#include "device.h"
#include "queueing.h"
#include "timers.h"
#include "hashtables.h"
#include "noise.h"
#include <linux/kref.h>
#include <linux/lockdep.h>
#include <linux/rcupdate.h>
#include <linux/list.h>
static atomic64_t peer_counter = ATOMIC64_INIT(0);
struct wireguard_peer *peer_create(struct wireguard_device *wg, const u8 public_key[NOISE_PUBLIC_KEY_LEN], const u8 preshared_key[NOISE_SYMMETRIC_KEY_LEN])
{
struct wireguard_peer *peer;
lockdep_assert_held(&wg->device_update_lock);
if (wg->num_peers >= MAX_PEERS_PER_DEVICE)
return NULL;
peer = kzalloc(sizeof(struct wireguard_peer), GFP_KERNEL);
if (!peer)
return NULL;
peer->device = wg;
if (!noise_handshake_init(&peer->handshake, &wg->static_identity, public_key, preshared_key, peer))
goto err_1;
if (dst_cache_init(&peer->endpoint_cache, GFP_KERNEL))
goto err_1;
if (packet_queue_init(&peer->tx_queue, packet_tx_worker, false, MAX_QUEUED_PACKETS))
goto err_2;
if (packet_queue_init(&peer->rx_queue, NULL, false, MAX_QUEUED_PACKETS))
goto err_3;
peer->internal_id = atomic64_inc_return(&peer_counter);
peer->serial_work_cpu = nr_cpumask_bits;
cookie_init(&peer->latest_cookie);
timers_init(peer);
cookie_checker_precompute_peer_keys(peer);
spin_lock_init(&peer->keypairs.keypair_update_lock);
INIT_WORK(&peer->transmit_handshake_work, packet_handshake_send_worker);
rwlock_init(&peer->endpoint_lock);
kref_init(&peer->refcount);
skb_queue_head_init(&peer->staged_packet_queue);
atomic64_set(&peer->last_sent_handshake, ktime_get_boot_fast_ns() - (u64)(REKEY_TIMEOUT + 1) * NSEC_PER_SEC);
set_bit(NAPI_STATE_NO_BUSY_POLL, &peer->napi.state);
netif_napi_add(wg->dev, &peer->napi, packet_rx_poll, NAPI_POLL_WEIGHT);
napi_enable(&peer->napi);
list_add_tail(&peer->peer_list, &wg->peer_list);
pubkey_hashtable_add(&wg->peer_hashtable, peer);
++wg->num_peers;
pr_debug("%s: Peer %llu created\n", wg->dev->name, peer->internal_id);
return peer;
err_3:
packet_queue_free(&peer->tx_queue, false);
err_2:
dst_cache_destroy(&peer->endpoint_cache);
err_1:
kfree(peer);
return NULL;
}
struct wireguard_peer *peer_get_maybe_zero(struct wireguard_peer *peer)
{
RCU_LOCKDEP_WARN(!rcu_read_lock_bh_held(), "Taking peer reference without holding the RCU read lock");
if (unlikely(!peer || !kref_get_unless_zero(&peer->refcount)))
return NULL;
return peer;
}
/* We have a separate "remove" function to get rid of the final reference because
* peer_list, clearing handshakes, and flushing all require mutexes which requires
* sleeping, which must only be done from certain contexts.
*/
void peer_remove(struct wireguard_peer *peer)
{
if (unlikely(!peer))
return;
lockdep_assert_held(&peer->device->device_update_lock);
/* Remove from configuration-time lookup structures so new packets can't enter. */
list_del_init(&peer->peer_list);
allowedips_remove_by_peer(&peer->device->peer_allowedips, peer, &peer->device->device_update_lock);
pubkey_hashtable_remove(&peer->device->peer_hashtable, peer);
/* Mark as dead, so that we don't allow jumping contexts after. */
WRITE_ONCE(peer->is_dead, true);
synchronize_rcu_bh();
/* Now that no more keypairs can be created for this peer, we destroy existing ones. */
noise_keypairs_clear(&peer->keypairs);
/* Destroy all ongoing timers that were in-flight at the beginning of this function. */
timers_stop(peer);
/* The transition between packet encryption/decryption queues isn't guarded
* by is_dead, but each reference's life is strictly bounded by two
* generations: once for parallel crypto and once for serial ingestion,
* so we can simply flush twice, and be sure that we no longer have references
* inside these queues.
*
* a) For encrypt/decrypt. */
flush_workqueue(peer->device->packet_crypt_wq);
/* b.1) For send (but not receive, since that's napi). */
flush_workqueue(peer->device->packet_crypt_wq);
/* b.2.1) For receive (but not send, since that's wq). */
napi_disable(&peer->napi);
/* b.2.1) It's now safe to remove the napi struct, which must be done here from process context. */
netif_napi_del(&peer->napi);
/* Ensure any workstructs we own (like transmit_handshake_work or clear_peer_work) no longer are in use. */
flush_workqueue(peer->device->handshake_send_wq);
--peer->device->num_peers;
peer_put(peer);
}
static void rcu_release(struct rcu_head *rcu)
{
struct wireguard_peer *peer = container_of(rcu, struct wireguard_peer, rcu);
dst_cache_destroy(&peer->endpoint_cache);
packet_queue_free(&peer->rx_queue, false);
packet_queue_free(&peer->tx_queue, false);
kzfree(peer);
}
static void kref_release(struct kref *refcount)
{
struct wireguard_peer *peer = container_of(refcount, struct wireguard_peer, refcount);
pr_debug("%s: Peer %llu (%pISpfsc) destroyed\n", peer->device->dev->name, peer->internal_id, &peer->endpoint.addr);
/* Remove ourself from dynamic runtime lookup structures, now that the last reference is gone. */
index_hashtable_remove(&peer->device->index_hashtable, &peer->handshake.entry);
/* Remove any lingering packets that didn't have a chance to be transmitted. */
skb_queue_purge(&peer->staged_packet_queue);
/* Free the memory used. */
call_rcu_bh(&peer->rcu, rcu_release);
}
void peer_put(struct wireguard_peer *peer)
{
if (unlikely(!peer))
return;
kref_put(&peer->refcount, kref_release);
}
void peer_remove_all(struct wireguard_device *wg)
{
struct wireguard_peer *peer, *temp;
lockdep_assert_held(&wg->device_update_lock);
list_for_each_entry_safe(peer, temp, &wg->peer_list, peer_list)
peer_remove(peer);
}
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