mirror of
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225 lines
9.2 KiB
Diff
225 lines
9.2 KiB
Diff
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
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Date: Wed, 18 Mar 2020 18:30:47 -0600
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Subject: [PATCH] wireguard: noise: error out precomputed DH during handshake
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rather than config
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commit 11a7686aa99c7fe4b3f80f6dcccd54129817984d upstream.
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We precompute the static-static ECDH during configuration time, in order
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to save an expensive computation later when receiving network packets.
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However, not all ECDH computations yield a contributory result. Prior,
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we were just not letting those peers be added to the interface. However,
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this creates a strange inconsistency, since it was still possible to add
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other weird points, like a valid public key plus a low-order point, and,
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like points that result in zeros, a handshake would not complete. In
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order to make the behavior more uniform and less surprising, simply
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allow all peers to be added. Then, we'll error out later when doing the
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crypto if there's an issue. This also adds more separation between the
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crypto layer and the configuration layer.
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Discussed-with: Mathias Hall-Andersen <mathias@hall-andersen.dk>
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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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---
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drivers/net/wireguard/netlink.c | 8 +---
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drivers/net/wireguard/noise.c | 55 ++++++++++++----------
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drivers/net/wireguard/noise.h | 12 ++---
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drivers/net/wireguard/peer.c | 7 +--
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tools/testing/selftests/wireguard/netns.sh | 15 ++++--
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5 files changed, 49 insertions(+), 48 deletions(-)
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--- a/drivers/net/wireguard/netlink.c
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+++ b/drivers/net/wireguard/netlink.c
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@@ -417,11 +417,7 @@ static int set_peer(struct wg_device *wg
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peer = wg_peer_create(wg, public_key, preshared_key);
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if (IS_ERR(peer)) {
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- /* Similar to the above, if the key is invalid, we skip
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- * it without fanfare, so that services don't need to
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- * worry about doing key validation themselves.
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- */
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- ret = PTR_ERR(peer) == -EKEYREJECTED ? 0 : PTR_ERR(peer);
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+ ret = PTR_ERR(peer);
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peer = NULL;
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goto out;
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}
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@@ -575,7 +571,7 @@ static int wg_set_device(struct sk_buff
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private_key);
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list_for_each_entry_safe(peer, temp, &wg->peer_list,
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peer_list) {
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- BUG_ON(!wg_noise_precompute_static_static(peer));
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+ wg_noise_precompute_static_static(peer);
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wg_noise_expire_current_peer_keypairs(peer);
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}
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wg_cookie_checker_precompute_device_keys(&wg->cookie_checker);
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--- a/drivers/net/wireguard/noise.c
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+++ b/drivers/net/wireguard/noise.c
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@@ -44,32 +44,23 @@ void __init wg_noise_init(void)
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}
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/* Must hold peer->handshake.static_identity->lock */
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-bool wg_noise_precompute_static_static(struct wg_peer *peer)
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+void wg_noise_precompute_static_static(struct wg_peer *peer)
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{
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- bool ret;
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-
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down_write(&peer->handshake.lock);
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- if (peer->handshake.static_identity->has_identity) {
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- ret = curve25519(
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- peer->handshake.precomputed_static_static,
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+ if (!peer->handshake.static_identity->has_identity ||
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+ !curve25519(peer->handshake.precomputed_static_static,
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peer->handshake.static_identity->static_private,
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- peer->handshake.remote_static);
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- } else {
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- u8 empty[NOISE_PUBLIC_KEY_LEN] = { 0 };
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-
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- ret = curve25519(empty, empty, peer->handshake.remote_static);
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+ peer->handshake.remote_static))
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memset(peer->handshake.precomputed_static_static, 0,
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NOISE_PUBLIC_KEY_LEN);
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- }
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up_write(&peer->handshake.lock);
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- return ret;
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}
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-bool wg_noise_handshake_init(struct noise_handshake *handshake,
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- struct noise_static_identity *static_identity,
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- const u8 peer_public_key[NOISE_PUBLIC_KEY_LEN],
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- const u8 peer_preshared_key[NOISE_SYMMETRIC_KEY_LEN],
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- struct wg_peer *peer)
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+void wg_noise_handshake_init(struct noise_handshake *handshake,
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+ struct noise_static_identity *static_identity,
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+ const u8 peer_public_key[NOISE_PUBLIC_KEY_LEN],
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+ const u8 peer_preshared_key[NOISE_SYMMETRIC_KEY_LEN],
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+ struct wg_peer *peer)
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{
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memset(handshake, 0, sizeof(*handshake));
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init_rwsem(&handshake->lock);
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@@ -81,7 +72,7 @@ bool wg_noise_handshake_init(struct nois
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NOISE_SYMMETRIC_KEY_LEN);
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handshake->static_identity = static_identity;
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handshake->state = HANDSHAKE_ZEROED;
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- return wg_noise_precompute_static_static(peer);
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+ wg_noise_precompute_static_static(peer);
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}
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static void handshake_zero(struct noise_handshake *handshake)
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@@ -403,6 +394,19 @@ static bool __must_check mix_dh(u8 chain
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return true;
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}
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+static bool __must_check mix_precomputed_dh(u8 chaining_key[NOISE_HASH_LEN],
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+ u8 key[NOISE_SYMMETRIC_KEY_LEN],
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+ const u8 precomputed[NOISE_PUBLIC_KEY_LEN])
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+{
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+ static u8 zero_point[NOISE_PUBLIC_KEY_LEN];
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+ if (unlikely(!crypto_memneq(precomputed, zero_point, NOISE_PUBLIC_KEY_LEN)))
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+ return false;
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+ kdf(chaining_key, key, NULL, precomputed, NOISE_HASH_LEN,
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+ NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
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+ chaining_key);
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+ return true;
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+}
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+
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static void mix_hash(u8 hash[NOISE_HASH_LEN], const u8 *src, size_t src_len)
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{
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struct blake2s_state blake;
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@@ -531,10 +535,9 @@ wg_noise_handshake_create_initiation(str
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NOISE_PUBLIC_KEY_LEN, key, handshake->hash);
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/* ss */
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- kdf(handshake->chaining_key, key, NULL,
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- handshake->precomputed_static_static, NOISE_HASH_LEN,
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- NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
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- handshake->chaining_key);
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+ if (!mix_precomputed_dh(handshake->chaining_key, key,
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+ handshake->precomputed_static_static))
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+ goto out;
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/* {t} */
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tai64n_now(timestamp);
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@@ -595,9 +598,9 @@ wg_noise_handshake_consume_initiation(st
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handshake = &peer->handshake;
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/* ss */
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- kdf(chaining_key, key, NULL, handshake->precomputed_static_static,
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- NOISE_HASH_LEN, NOISE_SYMMETRIC_KEY_LEN, 0, NOISE_PUBLIC_KEY_LEN,
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- chaining_key);
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+ if (!mix_precomputed_dh(chaining_key, key,
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+ handshake->precomputed_static_static))
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+ goto out;
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/* {t} */
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if (!message_decrypt(t, src->encrypted_timestamp,
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--- a/drivers/net/wireguard/noise.h
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+++ b/drivers/net/wireguard/noise.h
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@@ -94,11 +94,11 @@ struct noise_handshake {
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struct wg_device;
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void wg_noise_init(void);
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-bool wg_noise_handshake_init(struct noise_handshake *handshake,
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- struct noise_static_identity *static_identity,
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- const u8 peer_public_key[NOISE_PUBLIC_KEY_LEN],
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- const u8 peer_preshared_key[NOISE_SYMMETRIC_KEY_LEN],
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- struct wg_peer *peer);
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+void wg_noise_handshake_init(struct noise_handshake *handshake,
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+ struct noise_static_identity *static_identity,
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+ const u8 peer_public_key[NOISE_PUBLIC_KEY_LEN],
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+ const u8 peer_preshared_key[NOISE_SYMMETRIC_KEY_LEN],
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+ struct wg_peer *peer);
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void wg_noise_handshake_clear(struct noise_handshake *handshake);
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static inline void wg_noise_reset_last_sent_handshake(atomic64_t *handshake_ns)
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{
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@@ -116,7 +116,7 @@ void wg_noise_expire_current_peer_keypai
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void wg_noise_set_static_identity_private_key(
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struct noise_static_identity *static_identity,
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const u8 private_key[NOISE_PUBLIC_KEY_LEN]);
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-bool wg_noise_precompute_static_static(struct wg_peer *peer);
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+void wg_noise_precompute_static_static(struct wg_peer *peer);
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bool
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wg_noise_handshake_create_initiation(struct message_handshake_initiation *dst,
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--- a/drivers/net/wireguard/peer.c
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+++ b/drivers/net/wireguard/peer.c
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@@ -34,11 +34,8 @@ struct wg_peer *wg_peer_create(struct wg
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return ERR_PTR(ret);
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peer->device = wg;
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- if (!wg_noise_handshake_init(&peer->handshake, &wg->static_identity,
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- public_key, preshared_key, peer)) {
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- ret = -EKEYREJECTED;
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- goto err_1;
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- }
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+ wg_noise_handshake_init(&peer->handshake, &wg->static_identity,
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+ public_key, preshared_key, peer);
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if (dst_cache_init(&peer->endpoint_cache, GFP_KERNEL))
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goto err_1;
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if (wg_packet_queue_init(&peer->tx_queue, wg_packet_tx_worker, false,
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--- a/tools/testing/selftests/wireguard/netns.sh
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+++ b/tools/testing/selftests/wireguard/netns.sh
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@@ -527,11 +527,16 @@ n0 wg set wg0 peer "$pub2" allowed-ips 0
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n0 wg set wg0 peer "$pub2" allowed-ips ::/0,1700::/111,5000::/4,e000::/37,9000::/75
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n0 wg set wg0 peer "$pub2" allowed-ips ::/0
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n0 wg set wg0 peer "$pub2" remove
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-low_order_points=( AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= 4Ot6fDtBuK4WVuP68Z/EatoJjeucMrH9hmIFFl9JuAA= X5yVvKNQjCSx0LFVnIPvWwREXMRYHI6G2CJO3dCfEVc= 7P///////////////////////////////////////38= 7f///////////////////////////////////////38= 7v///////////////////////////////////////38= )
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-n0 wg set wg0 private-key /dev/null ${low_order_points[@]/#/peer }
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-[[ -z $(n0 wg show wg0 peers) ]]
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-n0 wg set wg0 private-key <(echo "$key1") ${low_order_points[@]/#/peer }
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-[[ -z $(n0 wg show wg0 peers) ]]
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+for low_order_point in AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA= 4Ot6fDtBuK4WVuP68Z/EatoJjeucMrH9hmIFFl9JuAA= X5yVvKNQjCSx0LFVnIPvWwREXMRYHI6G2CJO3dCfEVc= 7P///////////////////////////////////////38= 7f///////////////////////////////////////38= 7v///////////////////////////////////////38=; do
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+ n0 wg set wg0 peer "$low_order_point" persistent-keepalive 1 endpoint 127.0.0.1:1111
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+done
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+[[ -n $(n0 wg show wg0 peers) ]]
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+exec 4< <(n0 ncat -l -u -p 1111)
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+ncat_pid=$!
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+waitncatudp $netns0 $ncat_pid
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+ip0 link set wg0 up
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+! read -r -n 1 -t 2 <&4 || false
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+kill $ncat_pid
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ip0 link del wg0
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declare -A objects
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