blob: 626433690abb396deb80315856648bd1adda7276 [file] [log] [blame]
// 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);
}
/* Must hold peer->handshake.static_identity->lock */
void wg_noise_precompute_static_static(struct wg_peer *peer)
{
down_write(&peer->handshake.lock);
if (!peer->handshake.static_identity->has_identity ||
!curve25519(peer->handshake.precomputed_static_static,
peer->handshake.static_identity->static_private,
peer->handshake.remote_static))
memset(peer->handshake.precomputed_static_static, 0,
NOISE_PUBLIC_KEY_LEN);
up_write(&peer->handshake.lock);
}
void 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;
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;
spin_lock_init(&keypair->receiving_counter.lock);
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);
}
void wg_noise_expire_current_peer_keypairs(struct wg_peer *peer)
{
struct noise_keypair *keypair;
wg_noise_handshake_clear(&peer->handshake);
wg_noise_reset_last_sent_handshake(&peer->last_sent_handshake);
spin_lock_bh(&peer->keypairs.keypair_update_lock);
keypair = rcu_dereference_protected(peer->keypairs.next_keypair,
lockdep_is_held(&peer->keypairs.keypair_update_lock));
if (keypair)
keypair->sending.is_valid = false;
keypair = rcu_dereference_protected(peer->keypairs.current_keypair,
lockdep_is_held(&peer->keypairs.keypair_update_lock));
if (keypair)
keypair->sending.is_valid = false;
spin_unlock_bh(&peer->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 */
blake2s256_hmac(secret, data, chaining_key, data_len, NOISE_HASH_LEN);
if (!first_dst || !first_len)
goto out;
/* Expand first key: key = secret, data = 0x1 */
output[0] = 1;
blake2s256_hmac(output, output, secret, 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;
blake2s256_hmac(output, output, secret, 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;
blake2s256_hmac(output, output, secret, 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 derive_keys(struct noise_symmetric_key *first_dst,
struct noise_symmetric_key *second_dst,
const u8 chaining_key[NOISE_HASH_LEN])
{
u64 birthdate = ktime_get_coarse_boottime_ns();
kdf(first_dst->key, second_dst->key, NULL, NULL,
NOISE_SYMMETRIC_KEY_LEN, NOISE_SYMMETRIC_KEY_LEN, 0, 0,
chaining_key);
first_dst->birthdate = second_dst->birthdate = birthdate;
first_dst->is_valid = second_dst->is_valid = true;
}
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 bool __must_check mix_precomputed_dh(u8 chaining_key[NOISE_HASH_LEN],
u8 key[NOISE_SYMMETRIC_KEY_LEN],
const u8 precomputed[NOISE_PUBLIC_KEY_LEN])
{
static u8 zero_point[NOISE_PUBLIC_KEY_LEN];
if (unlikely(!crypto_memneq(precomputed, zero_point, NOISE_PUBLIC_KEY_LEN)))
return false;
kdf(chaining_key, key, NULL, precomputed, NOISE_HASH_LEN,
NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
chaining_key);
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);
}
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 */
if (!mix_precomputed_dh(handshake->chaining_key, key,
handshake->precomputed_static_static))
goto out;
/* {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];
u64 initiation_consumption;
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 */
if (!mix_precomputed_dh(chaining_key, key,
handshake->precomputed_static_static))
goto out;
/* {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 = (s64)handshake->last_initiation_consumption +
NSEC_PER_SEC / INITIATIONS_PER_SECOND >
(s64)ktime_get_coarse_boottime_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);
if (memcmp(t, handshake->latest_timestamp, NOISE_TIMESTAMP_LEN) > 0)
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;
if ((s64)(handshake->last_initiation_consumption -
(initiation_consumption = ktime_get_coarse_boottime_ns())) < 0)
handshake->last_initiation_consumption = initiation_consumption;
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];
u8 preshared_key[NOISE_SYMMETRIC_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);
memcpy(preshared_key, handshake->preshared_key,
NOISE_SYMMETRIC_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, 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);
memzero_explicit(preshared_key, NOISE_SYMMETRIC_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;
}