Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 861 insertions, 0 deletions

diff --git a/drivers/net/wireguard/noise.c b/drivers/net/wireguard/noise.c
new file mode 100644
index 0000000000..720952b92e
--- /dev/null
+++ b/drivers/net/wireguard/noise.c
@@ -0,0 +1,861 @@
+// 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)
+{
+	down_write(&handshake->lock);
+	wg_index_hashtable_remove(
+			handshake->entry.peer->device->index_hashtable,
+			&handshake->entry);
+	handshake_zero(handshake);
+	up_write(&handshake->lock);
+}
+
+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)
+{
+	kfree_sensitive(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);
+}
+
+static void hmac(u8 *out, const u8 *in, const u8 *key, const size_t inlen, const size_t keylen)
+{
+	struct blake2s_state state;
+	u8 x_key[BLAKE2S_BLOCK_SIZE] __aligned(__alignof__(u32)) = { 0 };
+	u8 i_hash[BLAKE2S_HASH_SIZE] __aligned(__alignof__(u32));
+	int i;
+
+	if (keylen > BLAKE2S_BLOCK_SIZE) {
+		blake2s_init(&state, BLAKE2S_HASH_SIZE);
+		blake2s_update(&state, key, keylen);
+		blake2s_final(&state, x_key);
+	} else
+		memcpy(x_key, key, keylen);
+
+	for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
+		x_key[i] ^= 0x36;
+
+	blake2s_init(&state, BLAKE2S_HASH_SIZE);
+	blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
+	blake2s_update(&state, in, inlen);
+	blake2s_final(&state, i_hash);
+
+	for (i = 0; i < BLAKE2S_BLOCK_SIZE; ++i)
+		x_key[i] ^= 0x5c ^ 0x36;
+
+	blake2s_init(&state, BLAKE2S_HASH_SIZE);
+	blake2s_update(&state, x_key, BLAKE2S_BLOCK_SIZE);
+	blake2s_update(&state, i_hash, BLAKE2S_HASH_SIZE);
+	blake2s_final(&state, i_hash);
+
+	memcpy(out, i_hash, BLAKE2S_HASH_SIZE);
+	memzero_explicit(x_key, BLAKE2S_BLOCK_SIZE);
+	memzero_explicit(i_hash, BLAKE2S_HASH_SIZE);
+}
+
+/* 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 */
+	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;
+	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;
+	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;
+	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;
+	initiation_consumption = ktime_get_coarse_boottime_ns();
+	if ((s64)(handshake->last_initiation_consumption - initiation_consumption) < 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 {
+		kfree_sensitive(new_keypair);
+	}
+	rcu_read_unlock_bh();
+
+out:
+	up_write(&handshake->lock);
+	return ret;
+}