diff options
Diffstat (limited to 'src/hashtables.c')
-rw-r--r-- | src/hashtables.c | 168 |
1 files changed, 0 insertions, 168 deletions
diff --git a/src/hashtables.c b/src/hashtables.c deleted file mode 100644 index 0e5235d..0000000 --- a/src/hashtables.c +++ /dev/null @@ -1,168 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 - * - * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. - */ - -#include "hashtables.h" -#include "peer.h" -#include "noise.h" - -static inline struct hlist_head *pubkey_bucket(struct pubkey_hashtable *table, const u8 pubkey[NOISE_PUBLIC_KEY_LEN]) -{ - /* siphash gives us a secure 64bit number based on a random key. Since the bits are - * uniformly distributed, we can then mask off to get the bits we need. - */ - return &table->hashtable[siphash(pubkey, NOISE_PUBLIC_KEY_LEN, &table->key) & (HASH_SIZE(table->hashtable) - 1)]; -} - -void pubkey_hashtable_init(struct pubkey_hashtable *table) -{ - get_random_bytes(&table->key, sizeof(table->key)); - hash_init(table->hashtable); - mutex_init(&table->lock); -} - -void pubkey_hashtable_add(struct pubkey_hashtable *table, struct wireguard_peer *peer) -{ - mutex_lock(&table->lock); - hlist_add_head_rcu(&peer->pubkey_hash, pubkey_bucket(table, peer->handshake.remote_static)); - mutex_unlock(&table->lock); -} - -void pubkey_hashtable_remove(struct pubkey_hashtable *table, struct wireguard_peer *peer) -{ - mutex_lock(&table->lock); - hlist_del_init_rcu(&peer->pubkey_hash); - mutex_unlock(&table->lock); -} - -/* Returns a strong reference to a peer */ -struct wireguard_peer *pubkey_hashtable_lookup(struct pubkey_hashtable *table, const u8 pubkey[NOISE_PUBLIC_KEY_LEN]) -{ - struct wireguard_peer *iter_peer, *peer = NULL; - - rcu_read_lock_bh(); - hlist_for_each_entry_rcu_bh(iter_peer, pubkey_bucket(table, pubkey), pubkey_hash) { - if (!memcmp(pubkey, iter_peer->handshake.remote_static, NOISE_PUBLIC_KEY_LEN)) { - peer = iter_peer; - break; - } - } - peer = peer_get(peer); - rcu_read_unlock_bh(); - return peer; -} - -static inline struct hlist_head *index_bucket(struct index_hashtable *table, const __le32 index) -{ - /* Since the indices are random and thus all bits are uniformly distributed, - * we can find its bucket simply by masking. - */ - return &table->hashtable[(__force u32)index & (HASH_SIZE(table->hashtable) - 1)]; -} - -void index_hashtable_init(struct index_hashtable *table) -{ - hash_init(table->hashtable); - spin_lock_init(&table->lock); -} - -/* At the moment, we limit ourselves to 2^20 total peers, which generally might amount to 2^20*3 - * items in this hashtable. The algorithm below works by picking a random number and testing it. - * We can see that these limits mean we usually succeed pretty quickly: - * - * >>> def calculation(tries, size): - * ... return (size / 2**32)**(tries - 1) * (1 - (size / 2**32)) - * ... - * >>> calculation(1, 2**20 * 3) - * 0.999267578125 - * >>> calculation(2, 2**20 * 3) - * 0.0007318854331970215 - * >>> calculation(3, 2**20 * 3) - * 5.360489012673497e-07 - * >>> calculation(4, 2**20 * 3) - * 3.9261394135792216e-10 - * - * At the moment, we don't do any masking, so this algorithm isn't exactly constant time in - * either the random guessing or in the hash list lookup. We could require a minimum of 3 - * tries, which would successfully mask the guessing. TODO: this would not, however, help - * with the growing hash lengths. - */ - -__le32 index_hashtable_insert(struct index_hashtable *table, struct index_hashtable_entry *entry) -{ - struct index_hashtable_entry *existing_entry; - - spin_lock_bh(&table->lock); - hlist_del_init_rcu(&entry->index_hash); - spin_unlock_bh(&table->lock); - - rcu_read_lock_bh(); - -search_unused_slot: - /* First we try to find an unused slot, randomly, while unlocked. */ - entry->index = (__force __le32)get_random_u32(); - hlist_for_each_entry_rcu_bh(existing_entry, index_bucket(table, entry->index), index_hash) { - if (existing_entry->index == entry->index) - goto search_unused_slot; /* If it's already in use, we continue searching. */ - } - - /* Once we've found an unused slot, we lock it, and then double-check - * that nobody else stole it from us. - */ - spin_lock_bh(&table->lock); - hlist_for_each_entry_rcu_bh(existing_entry, index_bucket(table, entry->index), index_hash) { - if (existing_entry->index == entry->index) { - spin_unlock_bh(&table->lock); - goto search_unused_slot; /* If it was stolen, we start over. */ - } - } - /* Otherwise, we know we have it exclusively (since we're locked), so we insert. */ - hlist_add_head_rcu(&entry->index_hash, index_bucket(table, entry->index)); - spin_unlock_bh(&table->lock); - - rcu_read_unlock_bh(); - - return entry->index; -} - -bool index_hashtable_replace(struct index_hashtable *table, struct index_hashtable_entry *old, struct index_hashtable_entry *new) -{ - if (unlikely(hlist_unhashed(&old->index_hash))) - return false; - spin_lock_bh(&table->lock); - new->index = old->index; - hlist_replace_rcu(&old->index_hash, &new->index_hash); - INIT_HLIST_NODE(&old->index_hash); - spin_unlock_bh(&table->lock); - return true; -} - -void index_hashtable_remove(struct index_hashtable *table, struct index_hashtable_entry *entry) -{ - spin_lock_bh(&table->lock); - hlist_del_init_rcu(&entry->index_hash); - spin_unlock_bh(&table->lock); -} - -/* Returns a strong reference to a entry->peer */ -struct index_hashtable_entry *index_hashtable_lookup(struct index_hashtable *table, const enum index_hashtable_type type_mask, const __le32 index) -{ - struct index_hashtable_entry *iter_entry, *entry = NULL; - - rcu_read_lock_bh(); - hlist_for_each_entry_rcu_bh(iter_entry, index_bucket(table, index), index_hash) { - if (iter_entry->index == index) { - if (likely(iter_entry->type & type_mask)) - entry = iter_entry; - break; - } - } - if (likely(entry)) { - entry->peer = peer_get(entry->peer); - if (unlikely(!entry->peer)) - entry = NULL; - } - rcu_read_unlock_bh(); - return entry; -} |