diff options
Diffstat (limited to 'drivers/net/wireguard/noise.c')
| -rw-r--r-- | drivers/net/wireguard/noise.c | 861 |
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 000000000..720952b92 --- /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; +} |