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path: root/drivers/net/wireguard/peer.c
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-rw-r--r--drivers/net/wireguard/peer.c239
1 files changed, 239 insertions, 0 deletions
diff --git a/drivers/net/wireguard/peer.c b/drivers/net/wireguard/peer.c
new file mode 100644
index 000000000000..508f1d5b4444
--- /dev/null
+++ b/drivers/net/wireguard/peer.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "peer.h"
+#include "device.h"
+#include "queueing.h"
+#include "timers.h"
+#include "peerlookup.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 wg_peer *wg_peer_create(struct wg_device *wg,
+ const u8 public_key[NOISE_PUBLIC_KEY_LEN],
+ const u8 preshared_key[NOISE_SYMMETRIC_KEY_LEN])
+{
+ struct wg_peer *peer;
+
+ lockdep_assert_held(&wg->device_update_lock);
+
+ if (wg->num_peers >= MAX_PEERS_PER_DEVICE)
+ return NULL;
+
+ peer = kzalloc(sizeof(*peer), GFP_KERNEL);
+ if (unlikely(!peer))
+ return NULL;
+ peer->device = wg;
+
+ if (!wg_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 (wg_packet_queue_init(&peer->tx_queue, wg_packet_tx_worker, false,
+ MAX_QUEUED_PACKETS))
+ goto err_2;
+ if (wg_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;
+ wg_cookie_init(&peer->latest_cookie);
+ wg_timers_init(peer);
+ wg_cookie_checker_precompute_peer_keys(peer);
+ spin_lock_init(&peer->keypairs.keypair_update_lock);
+ INIT_WORK(&peer->transmit_handshake_work,
+ wg_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, wg_packet_rx_poll,
+ NAPI_POLL_WEIGHT);
+ napi_enable(&peer->napi);
+ list_add_tail(&peer->peer_list, &wg->peer_list);
+ INIT_LIST_HEAD(&peer->allowedips_list);
+ wg_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:
+ wg_packet_queue_free(&peer->tx_queue, false);
+err_2:
+ dst_cache_destroy(&peer->endpoint_cache);
+err_1:
+ kfree(peer);
+ return NULL;
+}
+
+struct wg_peer *wg_peer_get_maybe_zero(struct wg_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;
+}
+
+static void peer_make_dead(struct wg_peer *peer)
+{
+ /* Remove from configuration-time lookup structures. */
+ list_del_init(&peer->peer_list);
+ wg_allowedips_remove_by_peer(&peer->device->peer_allowedips, peer,
+ &peer->device->device_update_lock);
+ wg_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);
+
+ /* The caller must now synchronize_rcu() for this to take effect. */
+}
+
+static void peer_remove_after_dead(struct wg_peer *peer)
+{
+ WARN_ON(!peer->is_dead);
+
+ /* No more keypairs can be created for this peer, since is_dead protects
+ * add_new_keypair, so we can now destroy existing ones.
+ */
+ wg_noise_keypairs_clear(&peer->keypairs);
+
+ /* Destroy all ongoing timers that were in-flight at the beginning of
+ * this function.
+ */
+ wg_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);
+
+ /* After the above flushes, a peer might still be active in a few
+ * different contexts: 1) from xmit(), before hitting is_dead and
+ * returning, 2) from wg_packet_consume_data(), before hitting is_dead
+ * and returning, 3) from wg_receive_handshake_packet() after a point
+ * where it has processed an incoming handshake packet, but where
+ * all calls to pass it off to timers fails because of is_dead. We won't
+ * have new references in (1) eventually, because we're removed from
+ * allowedips; we won't have new references in (2) eventually, because
+ * wg_index_hashtable_lookup will always return NULL, since we removed
+ * all existing keypairs and no more can be created; we won't have new
+ * references in (3) eventually, because we're removed from the pubkey
+ * hash table, which allows for a maximum of one handshake response,
+ * via the still-uncleared index hashtable entry, but not more than one,
+ * and in wg_cookie_message_consume, the lookup eventually gets a peer
+ * with a refcount of zero, so no new reference is taken.
+ */
+
+ --peer->device->num_peers;
+ wg_peer_put(peer);
+}
+
+/* We have a separate "remove" function make sure that all active places where
+ * a peer is currently operating will eventually come to an end and not pass
+ * their reference onto another context.
+ */
+void wg_peer_remove(struct wg_peer *peer)
+{
+ if (unlikely(!peer))
+ return;
+ lockdep_assert_held(&peer->device->device_update_lock);
+
+ peer_make_dead(peer);
+ synchronize_rcu();
+ peer_remove_after_dead(peer);
+}
+
+void wg_peer_remove_all(struct wg_device *wg)
+{
+ struct list_head dead_peers = LIST_HEAD_INIT(dead_peers);
+ struct wg_peer *peer, *temp;
+
+ lockdep_assert_held(&wg->device_update_lock);
+
+ /* Avoid having to traverse individually for each one. */
+ wg_allowedips_free(&wg->peer_allowedips, &wg->device_update_lock);
+
+ list_for_each_entry_safe(peer, temp, &wg->peer_list, peer_list) {
+ peer_make_dead(peer);
+ list_add_tail(&peer->peer_list, &dead_peers);
+ }
+ synchronize_rcu();
+ list_for_each_entry_safe(peer, temp, &dead_peers, peer_list)
+ peer_remove_after_dead(peer);
+}
+
+static void rcu_release(struct rcu_head *rcu)
+{
+ struct wg_peer *peer = container_of(rcu, struct wg_peer, rcu);
+
+ dst_cache_destroy(&peer->endpoint_cache);
+ wg_packet_queue_free(&peer->rx_queue, false);
+ wg_packet_queue_free(&peer->tx_queue, false);
+
+ /* The final zeroing takes care of clearing any remaining handshake key
+ * material and other potentially sensitive information.
+ */
+ kzfree(peer);
+}
+
+static void kref_release(struct kref *refcount)
+{
+ struct wg_peer *peer = container_of(refcount, struct wg_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.
+ */
+ wg_index_hashtable_remove(peer->device->index_hashtable,
+ &peer->handshake.entry);
+
+ /* Remove any lingering packets that didn't have a chance to be
+ * transmitted.
+ */
+ wg_packet_purge_staged_packets(peer);
+
+ /* Free the memory used. */
+ call_rcu(&peer->rcu, rcu_release);
+}
+
+void wg_peer_put(struct wg_peer *peer)
+{
+ if (unlikely(!peer))
+ return;
+ kref_put(&peer->refcount, kref_release);
+}