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path: root/drivers/net/wireguard/noise.c
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-rw-r--r--drivers/net/wireguard/noise.c807
1 files changed, 807 insertions, 0 deletions
diff --git a/drivers/net/wireguard/noise.c b/drivers/net/wireguard/noise.c
new file mode 100644
index 000000000000..bf0b8c5ab298
--- /dev/null
+++ b/drivers/net/wireguard/noise.c
@@ -0,0 +1,807 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "noise.h"
+#include "device.h"
+#include "peer.h"
+#include "messages.h"
+#include "queueing.h"
+#include "peerlookup.h"
+
+#include <linux/rcupdate.h>
+#include <linux/slab.h>
+#include <linux/bitmap.h>
+#include <linux/scatterlist.h>
+#include <linux/highmem.h>
+#include <crypto/algapi.h>
+
+/* This implements Noise_IKpsk2:
+ *
+ * <- s
+ * ******
+ * -> e, es, s, ss, {t}
+ * <- e, ee, se, psk, {}
+ */
+
+static const u8 handshake_name[37] = "Noise_IKpsk2_25519_ChaChaPoly_BLAKE2s";
+static const u8 identifier_name[34] = "WireGuard v1 zx2c4 Jason@zx2c4.com";
+static u8 handshake_init_hash[NOISE_HASH_LEN] __ro_after_init;
+static u8 handshake_init_chaining_key[NOISE_HASH_LEN] __ro_after_init;
+static atomic64_t keypair_counter = ATOMIC64_INIT(0);
+
+void __init wg_noise_init(void)
+{
+ struct blake2s_state blake;
+
+ blake2s(handshake_init_chaining_key, handshake_name, NULL,
+ NOISE_HASH_LEN, sizeof(handshake_name), 0);
+ blake2s_init(&blake, NOISE_HASH_LEN);
+ blake2s_update(&blake, handshake_init_chaining_key, NOISE_HASH_LEN);
+ blake2s_update(&blake, identifier_name, sizeof(identifier_name));
+ blake2s_final(&blake, handshake_init_hash, NOISE_HASH_LEN);
+}
+
+/* Must hold peer->handshake.static_identity->lock */
+bool wg_noise_precompute_static_static(struct wg_peer *peer)
+{
+ bool ret = true;
+
+ down_write(&peer->handshake.lock);
+ if (peer->handshake.static_identity->has_identity)
+ ret = curve25519(
+ peer->handshake.precomputed_static_static,
+ peer->handshake.static_identity->static_private,
+ peer->handshake.remote_static);
+ else
+ memset(peer->handshake.precomputed_static_static, 0,
+ NOISE_PUBLIC_KEY_LEN);
+ up_write(&peer->handshake.lock);
+ return ret;
+}
+
+bool wg_noise_handshake_init(struct noise_handshake *handshake,
+ struct noise_static_identity *static_identity,
+ const u8 peer_public_key[NOISE_PUBLIC_KEY_LEN],
+ const u8 peer_preshared_key[NOISE_SYMMETRIC_KEY_LEN],
+ struct wg_peer *peer)
+{
+ memset(handshake, 0, sizeof(*handshake));
+ init_rwsem(&handshake->lock);
+ handshake->entry.type = INDEX_HASHTABLE_HANDSHAKE;
+ handshake->entry.peer = peer;
+ memcpy(handshake->remote_static, peer_public_key, NOISE_PUBLIC_KEY_LEN);
+ if (peer_preshared_key)
+ memcpy(handshake->preshared_key, peer_preshared_key,
+ NOISE_SYMMETRIC_KEY_LEN);
+ handshake->static_identity = static_identity;
+ handshake->state = HANDSHAKE_ZEROED;
+ return wg_noise_precompute_static_static(peer);
+}
+
+static void handshake_zero(struct noise_handshake *handshake)
+{
+ memset(&handshake->ephemeral_private, 0, NOISE_PUBLIC_KEY_LEN);
+ memset(&handshake->remote_ephemeral, 0, NOISE_PUBLIC_KEY_LEN);
+ memset(&handshake->hash, 0, NOISE_HASH_LEN);
+ memset(&handshake->chaining_key, 0, NOISE_HASH_LEN);
+ handshake->remote_index = 0;
+ handshake->state = HANDSHAKE_ZEROED;
+}
+
+void wg_noise_handshake_clear(struct noise_handshake *handshake)
+{
+ wg_index_hashtable_remove(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry);
+ down_write(&handshake->lock);
+ handshake_zero(handshake);
+ up_write(&handshake->lock);
+ wg_index_hashtable_remove(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry);
+}
+
+static struct noise_keypair *keypair_create(struct wg_peer *peer)
+{
+ struct noise_keypair *keypair = kzalloc(sizeof(*keypair), GFP_KERNEL);
+
+ if (unlikely(!keypair))
+ return NULL;
+ keypair->internal_id = atomic64_inc_return(&keypair_counter);
+ keypair->entry.type = INDEX_HASHTABLE_KEYPAIR;
+ keypair->entry.peer = peer;
+ kref_init(&keypair->refcount);
+ return keypair;
+}
+
+static void keypair_free_rcu(struct rcu_head *rcu)
+{
+ kzfree(container_of(rcu, struct noise_keypair, rcu));
+}
+
+static void keypair_free_kref(struct kref *kref)
+{
+ struct noise_keypair *keypair =
+ container_of(kref, struct noise_keypair, refcount);
+
+ net_dbg_ratelimited("%s: Keypair %llu destroyed for peer %llu\n",
+ keypair->entry.peer->device->dev->name,
+ keypair->internal_id,
+ keypair->entry.peer->internal_id);
+ wg_index_hashtable_remove(keypair->entry.peer->device->index_hashtable,
+ &keypair->entry);
+ call_rcu(&keypair->rcu, keypair_free_rcu);
+}
+
+void wg_noise_keypair_put(struct noise_keypair *keypair, bool unreference_now)
+{
+ if (unlikely(!keypair))
+ return;
+ if (unlikely(unreference_now))
+ wg_index_hashtable_remove(
+ keypair->entry.peer->device->index_hashtable,
+ &keypair->entry);
+ kref_put(&keypair->refcount, keypair_free_kref);
+}
+
+struct noise_keypair *wg_noise_keypair_get(struct noise_keypair *keypair)
+{
+ RCU_LOCKDEP_WARN(!rcu_read_lock_bh_held(),
+ "Taking noise keypair reference without holding the RCU BH read lock");
+ if (unlikely(!keypair || !kref_get_unless_zero(&keypair->refcount)))
+ return NULL;
+ return keypair;
+}
+
+void wg_noise_keypairs_clear(struct noise_keypairs *keypairs)
+{
+ struct noise_keypair *old;
+
+ spin_lock_bh(&keypairs->keypair_update_lock);
+
+ /* We zero the next_keypair before zeroing the others, so that
+ * wg_noise_received_with_keypair returns early before subsequent ones
+ * are zeroed.
+ */
+ old = rcu_dereference_protected(keypairs->next_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ RCU_INIT_POINTER(keypairs->next_keypair, NULL);
+ wg_noise_keypair_put(old, true);
+
+ old = rcu_dereference_protected(keypairs->previous_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ RCU_INIT_POINTER(keypairs->previous_keypair, NULL);
+ wg_noise_keypair_put(old, true);
+
+ old = rcu_dereference_protected(keypairs->current_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ RCU_INIT_POINTER(keypairs->current_keypair, NULL);
+ wg_noise_keypair_put(old, true);
+
+ spin_unlock_bh(&keypairs->keypair_update_lock);
+}
+
+static void add_new_keypair(struct noise_keypairs *keypairs,
+ struct noise_keypair *new_keypair)
+{
+ struct noise_keypair *previous_keypair, *next_keypair, *current_keypair;
+
+ spin_lock_bh(&keypairs->keypair_update_lock);
+ previous_keypair = rcu_dereference_protected(keypairs->previous_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ next_keypair = rcu_dereference_protected(keypairs->next_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ current_keypair = rcu_dereference_protected(keypairs->current_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ if (new_keypair->i_am_the_initiator) {
+ /* If we're the initiator, it means we've sent a handshake, and
+ * received a confirmation response, which means this new
+ * keypair can now be used.
+ */
+ if (next_keypair) {
+ /* If there already was a next keypair pending, we
+ * demote it to be the previous keypair, and free the
+ * existing current. Note that this means KCI can result
+ * in this transition. It would perhaps be more sound to
+ * always just get rid of the unused next keypair
+ * instead of putting it in the previous slot, but this
+ * might be a bit less robust. Something to think about
+ * for the future.
+ */
+ RCU_INIT_POINTER(keypairs->next_keypair, NULL);
+ rcu_assign_pointer(keypairs->previous_keypair,
+ next_keypair);
+ wg_noise_keypair_put(current_keypair, true);
+ } else /* If there wasn't an existing next keypair, we replace
+ * the previous with the current one.
+ */
+ rcu_assign_pointer(keypairs->previous_keypair,
+ current_keypair);
+ /* At this point we can get rid of the old previous keypair, and
+ * set up the new keypair.
+ */
+ wg_noise_keypair_put(previous_keypair, true);
+ rcu_assign_pointer(keypairs->current_keypair, new_keypair);
+ } else {
+ /* If we're the responder, it means we can't use the new keypair
+ * until we receive confirmation via the first data packet, so
+ * we get rid of the existing previous one, the possibly
+ * existing next one, and slide in the new next one.
+ */
+ rcu_assign_pointer(keypairs->next_keypair, new_keypair);
+ wg_noise_keypair_put(next_keypair, true);
+ RCU_INIT_POINTER(keypairs->previous_keypair, NULL);
+ wg_noise_keypair_put(previous_keypair, true);
+ }
+ spin_unlock_bh(&keypairs->keypair_update_lock);
+}
+
+bool wg_noise_received_with_keypair(struct noise_keypairs *keypairs,
+ struct noise_keypair *received_keypair)
+{
+ struct noise_keypair *old_keypair;
+ bool key_is_new;
+
+ /* We first check without taking the spinlock. */
+ key_is_new = received_keypair ==
+ rcu_access_pointer(keypairs->next_keypair);
+ if (likely(!key_is_new))
+ return false;
+
+ spin_lock_bh(&keypairs->keypair_update_lock);
+ /* After locking, we double check that things didn't change from
+ * beneath us.
+ */
+ if (unlikely(received_keypair !=
+ rcu_dereference_protected(keypairs->next_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock)))) {
+ spin_unlock_bh(&keypairs->keypair_update_lock);
+ return false;
+ }
+
+ /* When we've finally received the confirmation, we slide the next
+ * into the current, the current into the previous, and get rid of
+ * the old previous.
+ */
+ old_keypair = rcu_dereference_protected(keypairs->previous_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock));
+ rcu_assign_pointer(keypairs->previous_keypair,
+ rcu_dereference_protected(keypairs->current_keypair,
+ lockdep_is_held(&keypairs->keypair_update_lock)));
+ wg_noise_keypair_put(old_keypair, true);
+ rcu_assign_pointer(keypairs->current_keypair, received_keypair);
+ RCU_INIT_POINTER(keypairs->next_keypair, NULL);
+
+ spin_unlock_bh(&keypairs->keypair_update_lock);
+ return true;
+}
+
+/* Must hold static_identity->lock */
+void wg_noise_set_static_identity_private_key(
+ struct noise_static_identity *static_identity,
+ const u8 private_key[NOISE_PUBLIC_KEY_LEN])
+{
+ memcpy(static_identity->static_private, private_key,
+ NOISE_PUBLIC_KEY_LEN);
+ curve25519_clamp_secret(static_identity->static_private);
+ static_identity->has_identity = curve25519_generate_public(
+ static_identity->static_public, private_key);
+}
+
+/* This is Hugo Krawczyk's HKDF:
+ * - https://eprint.iacr.org/2010/264.pdf
+ * - https://tools.ietf.org/html/rfc5869
+ */
+static void kdf(u8 *first_dst, u8 *second_dst, u8 *third_dst, const u8 *data,
+ size_t first_len, size_t second_len, size_t third_len,
+ size_t data_len, const u8 chaining_key[NOISE_HASH_LEN])
+{
+ u8 output[BLAKE2S_HASH_SIZE + 1];
+ u8 secret[BLAKE2S_HASH_SIZE];
+
+ WARN_ON(IS_ENABLED(DEBUG) &&
+ (first_len > BLAKE2S_HASH_SIZE ||
+ second_len > BLAKE2S_HASH_SIZE ||
+ third_len > BLAKE2S_HASH_SIZE ||
+ ((second_len || second_dst || third_len || third_dst) &&
+ (!first_len || !first_dst)) ||
+ ((third_len || third_dst) && (!second_len || !second_dst))));
+
+ /* Extract entropy from data into secret */
+ blake2s_hmac(secret, data, chaining_key, BLAKE2S_HASH_SIZE, data_len,
+ NOISE_HASH_LEN);
+
+ if (!first_dst || !first_len)
+ goto out;
+
+ /* Expand first key: key = secret, data = 0x1 */
+ output[0] = 1;
+ blake2s_hmac(output, output, secret, BLAKE2S_HASH_SIZE, 1,
+ BLAKE2S_HASH_SIZE);
+ memcpy(first_dst, output, first_len);
+
+ if (!second_dst || !second_len)
+ goto out;
+
+ /* Expand second key: key = secret, data = first-key || 0x2 */
+ output[BLAKE2S_HASH_SIZE] = 2;
+ blake2s_hmac(output, output, secret, BLAKE2S_HASH_SIZE,
+ BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE);
+ memcpy(second_dst, output, second_len);
+
+ if (!third_dst || !third_len)
+ goto out;
+
+ /* Expand third key: key = secret, data = second-key || 0x3 */
+ output[BLAKE2S_HASH_SIZE] = 3;
+ blake2s_hmac(output, output, secret, BLAKE2S_HASH_SIZE,
+ BLAKE2S_HASH_SIZE + 1, BLAKE2S_HASH_SIZE);
+ memcpy(third_dst, output, third_len);
+
+out:
+ /* Clear sensitive data from stack */
+ memzero_explicit(secret, BLAKE2S_HASH_SIZE);
+ memzero_explicit(output, BLAKE2S_HASH_SIZE + 1);
+}
+
+static void symmetric_key_init(struct noise_symmetric_key *key)
+{
+ spin_lock_init(&key->counter.receive.lock);
+ atomic64_set(&key->counter.counter, 0);
+ memset(key->counter.receive.backtrack, 0,
+ sizeof(key->counter.receive.backtrack));
+ key->birthdate = ktime_get_boot_fast_ns();
+ key->is_valid = true;
+}
+
+static void derive_keys(struct noise_symmetric_key *first_dst,
+ struct noise_symmetric_key *second_dst,
+ const u8 chaining_key[NOISE_HASH_LEN])
+{
+ kdf(first_dst->key, second_dst->key, NULL, NULL,
+ NOISE_SYMMETRIC_KEY_LEN, NOISE_SYMMETRIC_KEY_LEN, 0, 0,
+ chaining_key);
+ symmetric_key_init(first_dst);
+ symmetric_key_init(second_dst);
+}
+
+static bool __must_check mix_dh(u8 chaining_key[NOISE_HASH_LEN],
+ u8 key[NOISE_SYMMETRIC_KEY_LEN],
+ const u8 private[NOISE_PUBLIC_KEY_LEN],
+ const u8 public[NOISE_PUBLIC_KEY_LEN])
+{
+ u8 dh_calculation[NOISE_PUBLIC_KEY_LEN];
+
+ if (unlikely(!curve25519(dh_calculation, private, public)))
+ return false;
+ kdf(chaining_key, key, NULL, dh_calculation, NOISE_HASH_LEN,
+ NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN, chaining_key);
+ memzero_explicit(dh_calculation, NOISE_PUBLIC_KEY_LEN);
+ return true;
+}
+
+static void mix_hash(u8 hash[NOISE_HASH_LEN], const u8 *src, size_t src_len)
+{
+ struct blake2s_state blake;
+
+ blake2s_init(&blake, NOISE_HASH_LEN);
+ blake2s_update(&blake, hash, NOISE_HASH_LEN);
+ blake2s_update(&blake, src, src_len);
+ blake2s_final(&blake, hash, NOISE_HASH_LEN);
+}
+
+static void mix_psk(u8 chaining_key[NOISE_HASH_LEN], u8 hash[NOISE_HASH_LEN],
+ u8 key[NOISE_SYMMETRIC_KEY_LEN],
+ const u8 psk[NOISE_SYMMETRIC_KEY_LEN])
+{
+ u8 temp_hash[NOISE_HASH_LEN];
+
+ kdf(chaining_key, temp_hash, key, psk, NOISE_HASH_LEN, NOISE_HASH_LEN,
+ NOISE_SYMMETRIC_KEY_LEN, NOISE_SYMMETRIC_KEY_LEN, chaining_key);
+ mix_hash(hash, temp_hash, NOISE_HASH_LEN);
+ memzero_explicit(temp_hash, NOISE_HASH_LEN);
+}
+
+static void handshake_init(u8 chaining_key[NOISE_HASH_LEN],
+ u8 hash[NOISE_HASH_LEN],
+ const u8 remote_static[NOISE_PUBLIC_KEY_LEN])
+{
+ memcpy(hash, handshake_init_hash, NOISE_HASH_LEN);
+ memcpy(chaining_key, handshake_init_chaining_key, NOISE_HASH_LEN);
+ mix_hash(hash, remote_static, NOISE_PUBLIC_KEY_LEN);
+}
+
+static void message_encrypt(u8 *dst_ciphertext, const u8 *src_plaintext,
+ size_t src_len, u8 key[NOISE_SYMMETRIC_KEY_LEN],
+ u8 hash[NOISE_HASH_LEN])
+{
+ chacha20poly1305_encrypt(dst_ciphertext, src_plaintext, src_len, hash,
+ NOISE_HASH_LEN,
+ 0 /* Always zero for Noise_IK */, key);
+ mix_hash(hash, dst_ciphertext, noise_encrypted_len(src_len));
+}
+
+static bool message_decrypt(u8 *dst_plaintext, const u8 *src_ciphertext,
+ size_t src_len, u8 key[NOISE_SYMMETRIC_KEY_LEN],
+ u8 hash[NOISE_HASH_LEN])
+{
+ if (!chacha20poly1305_decrypt(dst_plaintext, src_ciphertext, src_len,
+ hash, NOISE_HASH_LEN,
+ 0 /* Always zero for Noise_IK */, key))
+ return false;
+ mix_hash(hash, src_ciphertext, src_len);
+ return true;
+}
+
+static void message_ephemeral(u8 ephemeral_dst[NOISE_PUBLIC_KEY_LEN],
+ const u8 ephemeral_src[NOISE_PUBLIC_KEY_LEN],
+ u8 chaining_key[NOISE_HASH_LEN],
+ u8 hash[NOISE_HASH_LEN])
+{
+ if (ephemeral_dst != ephemeral_src)
+ memcpy(ephemeral_dst, ephemeral_src, NOISE_PUBLIC_KEY_LEN);
+ mix_hash(hash, ephemeral_src, NOISE_PUBLIC_KEY_LEN);
+ kdf(chaining_key, NULL, NULL, ephemeral_src, NOISE_HASH_LEN, 0, 0,
+ NOISE_PUBLIC_KEY_LEN, chaining_key);
+}
+
+static void tai64n_now(u8 output[NOISE_TIMESTAMP_LEN])
+{
+ struct timespec64 now;
+
+ ktime_get_real_ts64(&now);
+
+ /* In order to prevent some sort of infoleak from precise timers, we
+ * round down the nanoseconds part to the closest rounded-down power of
+ * two to the maximum initiations per second allowed anyway by the
+ * implementation.
+ */
+ now.tv_nsec = ALIGN_DOWN(now.tv_nsec,
+ rounddown_pow_of_two(NSEC_PER_SEC / INITIATIONS_PER_SECOND));
+
+ /* https://cr.yp.to/libtai/tai64.html */
+ *(__be64 *)output = cpu_to_be64(0x400000000000000aULL + now.tv_sec);
+ *(__be32 *)(output + sizeof(__be64)) = cpu_to_be32(now.tv_nsec);
+}
+
+bool
+wg_noise_handshake_create_initiation(struct message_handshake_initiation *dst,
+ struct noise_handshake *handshake)
+{
+ u8 timestamp[NOISE_TIMESTAMP_LEN];
+ u8 key[NOISE_SYMMETRIC_KEY_LEN];
+ bool ret = false;
+
+ /* We need to wait for crng _before_ taking any locks, since
+ * curve25519_generate_secret uses get_random_bytes_wait.
+ */
+ wait_for_random_bytes();
+
+ down_read(&handshake->static_identity->lock);
+ down_write(&handshake->lock);
+
+ if (unlikely(!handshake->static_identity->has_identity))
+ goto out;
+
+ dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_INITIATION);
+
+ handshake_init(handshake->chaining_key, handshake->hash,
+ handshake->remote_static);
+
+ /* e */
+ curve25519_generate_secret(handshake->ephemeral_private);
+ if (!curve25519_generate_public(dst->unencrypted_ephemeral,
+ handshake->ephemeral_private))
+ goto out;
+ message_ephemeral(dst->unencrypted_ephemeral,
+ dst->unencrypted_ephemeral, handshake->chaining_key,
+ handshake->hash);
+
+ /* es */
+ if (!mix_dh(handshake->chaining_key, key, handshake->ephemeral_private,
+ handshake->remote_static))
+ goto out;
+
+ /* s */
+ message_encrypt(dst->encrypted_static,
+ handshake->static_identity->static_public,
+ NOISE_PUBLIC_KEY_LEN, key, handshake->hash);
+
+ /* ss */
+ kdf(handshake->chaining_key, key, NULL,
+ handshake->precomputed_static_static, NOISE_HASH_LEN,
+ NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
+ handshake->chaining_key);
+
+ /* {t} */
+ tai64n_now(timestamp);
+ message_encrypt(dst->encrypted_timestamp, timestamp,
+ NOISE_TIMESTAMP_LEN, key, handshake->hash);
+
+ dst->sender_index = wg_index_hashtable_insert(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry);
+
+ handshake->state = HANDSHAKE_CREATED_INITIATION;
+ ret = true;
+
+out:
+ up_write(&handshake->lock);
+ up_read(&handshake->static_identity->lock);
+ memzero_explicit(key, NOISE_SYMMETRIC_KEY_LEN);
+ return ret;
+}
+
+struct wg_peer *
+wg_noise_handshake_consume_initiation(struct message_handshake_initiation *src,
+ struct wg_device *wg)
+{
+ struct wg_peer *peer = NULL, *ret_peer = NULL;
+ struct noise_handshake *handshake;
+ bool replay_attack, flood_attack;
+ u8 key[NOISE_SYMMETRIC_KEY_LEN];
+ u8 chaining_key[NOISE_HASH_LEN];
+ u8 hash[NOISE_HASH_LEN];
+ u8 s[NOISE_PUBLIC_KEY_LEN];
+ u8 e[NOISE_PUBLIC_KEY_LEN];
+ u8 t[NOISE_TIMESTAMP_LEN];
+
+ down_read(&wg->static_identity.lock);
+ if (unlikely(!wg->static_identity.has_identity))
+ goto out;
+
+ handshake_init(chaining_key, hash, wg->static_identity.static_public);
+
+ /* e */
+ message_ephemeral(e, src->unencrypted_ephemeral, chaining_key, hash);
+
+ /* es */
+ if (!mix_dh(chaining_key, key, wg->static_identity.static_private, e))
+ goto out;
+
+ /* s */
+ if (!message_decrypt(s, src->encrypted_static,
+ sizeof(src->encrypted_static), key, hash))
+ goto out;
+
+ /* Lookup which peer we're actually talking to */
+ peer = wg_pubkey_hashtable_lookup(wg->peer_hashtable, s);
+ if (!peer)
+ goto out;
+ handshake = &peer->handshake;
+
+ /* ss */
+ kdf(chaining_key, key, NULL, handshake->precomputed_static_static,
+ NOISE_HASH_LEN, NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
+ chaining_key);
+
+ /* {t} */
+ if (!message_decrypt(t, src->encrypted_timestamp,
+ sizeof(src->encrypted_timestamp), key, hash))
+ goto out;
+
+ down_read(&handshake->lock);
+ replay_attack = memcmp(t, handshake->latest_timestamp,
+ NOISE_TIMESTAMP_LEN) <= 0;
+ flood_attack = handshake->last_initiation_consumption +
+ NSEC_PER_SEC / INITIATIONS_PER_SECOND >
+ ktime_get_boot_fast_ns();
+ up_read(&handshake->lock);
+ if (replay_attack || flood_attack)
+ goto out;
+
+ /* Success! Copy everything to peer */
+ down_write(&handshake->lock);
+ memcpy(handshake->remote_ephemeral, e, NOISE_PUBLIC_KEY_LEN);
+ memcpy(handshake->latest_timestamp, t, NOISE_TIMESTAMP_LEN);
+ memcpy(handshake->hash, hash, NOISE_HASH_LEN);
+ memcpy(handshake->chaining_key, chaining_key, NOISE_HASH_LEN);
+ handshake->remote_index = src->sender_index;
+ handshake->last_initiation_consumption = ktime_get_boot_fast_ns();
+ handshake->state = HANDSHAKE_CONSUMED_INITIATION;
+ up_write(&handshake->lock);
+ ret_peer = peer;
+
+out:
+ memzero_explicit(key, NOISE_SYMMETRIC_KEY_LEN);
+ memzero_explicit(hash, NOISE_HASH_LEN);
+ memzero_explicit(chaining_key, NOISE_HASH_LEN);
+ up_read(&wg->static_identity.lock);
+ if (!ret_peer)
+ wg_peer_put(peer);
+ return ret_peer;
+}
+
+bool wg_noise_handshake_create_response(struct message_handshake_response *dst,
+ struct noise_handshake *handshake)
+{
+ u8 key[NOISE_SYMMETRIC_KEY_LEN];
+ bool ret = false;
+
+ /* We need to wait for crng _before_ taking any locks, since
+ * curve25519_generate_secret uses get_random_bytes_wait.
+ */
+ wait_for_random_bytes();
+
+ down_read(&handshake->static_identity->lock);
+ down_write(&handshake->lock);
+
+ if (handshake->state != HANDSHAKE_CONSUMED_INITIATION)
+ goto out;
+
+ dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_RESPONSE);
+ dst->receiver_index = handshake->remote_index;
+
+ /* e */
+ curve25519_generate_secret(handshake->ephemeral_private);
+ if (!curve25519_generate_public(dst->unencrypted_ephemeral,
+ handshake->ephemeral_private))
+ goto out;
+ message_ephemeral(dst->unencrypted_ephemeral,
+ dst->unencrypted_ephemeral, handshake->chaining_key,
+ handshake->hash);
+
+ /* ee */
+ if (!mix_dh(handshake->chaining_key, NULL, handshake->ephemeral_private,
+ handshake->remote_ephemeral))
+ goto out;
+
+ /* se */
+ if (!mix_dh(handshake->chaining_key, NULL, handshake->ephemeral_private,
+ handshake->remote_static))
+ goto out;
+
+ /* psk */
+ mix_psk(handshake->chaining_key, handshake->hash, key,
+ handshake->preshared_key);
+
+ /* {} */
+ message_encrypt(dst->encrypted_nothing, NULL, 0, key, handshake->hash);
+
+ dst->sender_index = wg_index_hashtable_insert(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry);
+
+ handshake->state = HANDSHAKE_CREATED_RESPONSE;
+ ret = true;
+
+out:
+ up_write(&handshake->lock);
+ up_read(&handshake->static_identity->lock);
+ memzero_explicit(key, NOISE_SYMMETRIC_KEY_LEN);
+ return ret;
+}
+
+struct wg_peer *
+wg_noise_handshake_consume_response(struct message_handshake_response *src,
+ struct wg_device *wg)
+{
+ enum noise_handshake_state state = HANDSHAKE_ZEROED;
+ struct wg_peer *peer = NULL, *ret_peer = NULL;
+ struct noise_handshake *handshake;
+ u8 key[NOISE_SYMMETRIC_KEY_LEN];
+ u8 hash[NOISE_HASH_LEN];
+ u8 chaining_key[NOISE_HASH_LEN];
+ u8 e[NOISE_PUBLIC_KEY_LEN];
+ u8 ephemeral_private[NOISE_PUBLIC_KEY_LEN];
+ u8 static_private[NOISE_PUBLIC_KEY_LEN];
+
+ down_read(&wg->static_identity.lock);
+
+ if (unlikely(!wg->static_identity.has_identity))
+ goto out;
+
+ handshake = (struct noise_handshake *)wg_index_hashtable_lookup(
+ wg->index_hashtable, INDEX_HASHTABLE_HANDSHAKE,
+ src->receiver_index, &peer);
+ if (unlikely(!handshake))
+ goto out;
+
+ down_read(&handshake->lock);
+ state = handshake->state;
+ memcpy(hash, handshake->hash, NOISE_HASH_LEN);
+ memcpy(chaining_key, handshake->chaining_key, NOISE_HASH_LEN);
+ memcpy(ephemeral_private, handshake->ephemeral_private,
+ NOISE_PUBLIC_KEY_LEN);
+ up_read(&handshake->lock);
+
+ if (state != HANDSHAKE_CREATED_INITIATION)
+ goto fail;
+
+ /* e */
+ message_ephemeral(e, src->unencrypted_ephemeral, chaining_key, hash);
+
+ /* ee */
+ if (!mix_dh(chaining_key, NULL, ephemeral_private, e))
+ goto fail;
+
+ /* se */
+ if (!mix_dh(chaining_key, NULL, wg->static_identity.static_private, e))
+ goto fail;
+
+ /* psk */
+ mix_psk(chaining_key, hash, key, handshake->preshared_key);
+
+ /* {} */
+ if (!message_decrypt(NULL, src->encrypted_nothing,
+ sizeof(src->encrypted_nothing), key, hash))
+ goto fail;
+
+ /* Success! Copy everything to peer */
+ down_write(&handshake->lock);
+ /* It's important to check that the state is still the same, while we
+ * have an exclusive lock.
+ */
+ if (handshake->state != state) {
+ up_write(&handshake->lock);
+ goto fail;
+ }
+ memcpy(handshake->remote_ephemeral, e, NOISE_PUBLIC_KEY_LEN);
+ memcpy(handshake->hash, hash, NOISE_HASH_LEN);
+ memcpy(handshake->chaining_key, chaining_key, NOISE_HASH_LEN);
+ handshake->remote_index = src->sender_index;
+ handshake->state = HANDSHAKE_CONSUMED_RESPONSE;
+ up_write(&handshake->lock);
+ ret_peer = peer;
+ goto out;
+
+fail:
+ wg_peer_put(peer);
+out:
+ memzero_explicit(key, NOISE_SYMMETRIC_KEY_LEN);
+ memzero_explicit(hash, NOISE_HASH_LEN);
+ memzero_explicit(chaining_key, NOISE_HASH_LEN);
+ memzero_explicit(ephemeral_private, NOISE_PUBLIC_KEY_LEN);
+ memzero_explicit(static_private, NOISE_PUBLIC_KEY_LEN);
+ up_read(&wg->static_identity.lock);
+ return ret_peer;
+}
+
+bool wg_noise_handshake_begin_session(struct noise_handshake *handshake,
+ struct noise_keypairs *keypairs)
+{
+ struct noise_keypair *new_keypair;
+ bool ret = false;
+
+ down_write(&handshake->lock);
+ if (handshake->state != HANDSHAKE_CREATED_RESPONSE &&
+ handshake->state != HANDSHAKE_CONSUMED_RESPONSE)
+ goto out;
+
+ new_keypair = keypair_create(handshake->entry.peer);
+ if (!new_keypair)
+ goto out;
+ new_keypair->i_am_the_initiator = handshake->state ==
+ HANDSHAKE_CONSUMED_RESPONSE;
+ new_keypair->remote_index = handshake->remote_index;
+
+ if (new_keypair->i_am_the_initiator)
+ derive_keys(&new_keypair->sending, &new_keypair->receiving,
+ handshake->chaining_key);
+ else
+ derive_keys(&new_keypair->receiving, &new_keypair->sending,
+ handshake->chaining_key);
+
+ handshake_zero(handshake);
+ rcu_read_lock_bh();
+ if (likely(!READ_ONCE(container_of(handshake, struct wg_peer,
+ handshake)->is_dead))) {
+ add_new_keypair(keypairs, new_keypair);
+ net_dbg_ratelimited("%s: Keypair %llu created for peer %llu\n",
+ handshake->entry.peer->device->dev->name,
+ new_keypair->internal_id,
+ handshake->entry.peer->internal_id);
+ ret = wg_index_hashtable_replace(
+ handshake->entry.peer->device->index_hashtable,
+ &handshake->entry, &new_keypair->entry);
+ } else {
+ kzfree(new_keypair);
+ }
+ rcu_read_unlock_bh();
+
+out:
+ up_write(&handshake->lock);
+ return ret;
+}