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-rw-r--r--drivers/net/wireguard/cookie.c236
1 files changed, 236 insertions, 0 deletions
diff --git a/drivers/net/wireguard/cookie.c b/drivers/net/wireguard/cookie.c
new file mode 100644
index 000000000000..bd23a14ff87f
--- /dev/null
+++ b/drivers/net/wireguard/cookie.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ */
+
+#include "cookie.h"
+#include "peer.h"
+#include "device.h"
+#include "messages.h"
+#include "ratelimiter.h"
+#include "timers.h"
+
+#include <zinc/blake2s.h>
+#include <zinc/chacha20poly1305.h>
+
+#include <net/ipv6.h>
+#include <crypto/algapi.h>
+
+void wg_cookie_checker_init(struct cookie_checker *checker,
+ struct wg_device *wg)
+{
+ init_rwsem(&checker->secret_lock);
+ checker->secret_birthdate = ktime_get_boot_fast_ns();
+ get_random_bytes(checker->secret, NOISE_HASH_LEN);
+ checker->device = wg;
+}
+
+enum { COOKIE_KEY_LABEL_LEN = 8 };
+static const u8 mac1_key_label[COOKIE_KEY_LABEL_LEN] = "mac1----";
+static const u8 cookie_key_label[COOKIE_KEY_LABEL_LEN] = "cookie--";
+
+static void precompute_key(u8 key[NOISE_SYMMETRIC_KEY_LEN],
+ const u8 pubkey[NOISE_PUBLIC_KEY_LEN],
+ const u8 label[COOKIE_KEY_LABEL_LEN])
+{
+ struct blake2s_state blake;
+
+ blake2s_init(&blake, NOISE_SYMMETRIC_KEY_LEN);
+ blake2s_update(&blake, label, COOKIE_KEY_LABEL_LEN);
+ blake2s_update(&blake, pubkey, NOISE_PUBLIC_KEY_LEN);
+ blake2s_final(&blake, key, NOISE_SYMMETRIC_KEY_LEN);
+}
+
+/* Must hold peer->handshake.static_identity->lock */
+void wg_cookie_checker_precompute_device_keys(struct cookie_checker *checker)
+{
+ if (likely(checker->device->static_identity.has_identity)) {
+ precompute_key(checker->cookie_encryption_key,
+ checker->device->static_identity.static_public,
+ cookie_key_label);
+ precompute_key(checker->message_mac1_key,
+ checker->device->static_identity.static_public,
+ mac1_key_label);
+ } else {
+ memset(checker->cookie_encryption_key, 0,
+ NOISE_SYMMETRIC_KEY_LEN);
+ memset(checker->message_mac1_key, 0, NOISE_SYMMETRIC_KEY_LEN);
+ }
+}
+
+void wg_cookie_checker_precompute_peer_keys(struct wg_peer *peer)
+{
+ precompute_key(peer->latest_cookie.cookie_decryption_key,
+ peer->handshake.remote_static, cookie_key_label);
+ precompute_key(peer->latest_cookie.message_mac1_key,
+ peer->handshake.remote_static, mac1_key_label);
+}
+
+void wg_cookie_init(struct cookie *cookie)
+{
+ memset(cookie, 0, sizeof(*cookie));
+ init_rwsem(&cookie->lock);
+}
+
+static void compute_mac1(u8 mac1[COOKIE_LEN], const void *message, size_t len,
+ const u8 key[NOISE_SYMMETRIC_KEY_LEN])
+{
+ len = len - sizeof(struct message_macs) +
+ offsetof(struct message_macs, mac1);
+ blake2s(mac1, message, key, COOKIE_LEN, len, NOISE_SYMMETRIC_KEY_LEN);
+}
+
+static void compute_mac2(u8 mac2[COOKIE_LEN], const void *message, size_t len,
+ const u8 cookie[COOKIE_LEN])
+{
+ len = len - sizeof(struct message_macs) +
+ offsetof(struct message_macs, mac2);
+ blake2s(mac2, message, cookie, COOKIE_LEN, len, COOKIE_LEN);
+}
+
+static void make_cookie(u8 cookie[COOKIE_LEN], struct sk_buff *skb,
+ struct cookie_checker *checker)
+{
+ struct blake2s_state state;
+
+ if (wg_birthdate_has_expired(checker->secret_birthdate,
+ COOKIE_SECRET_MAX_AGE)) {
+ down_write(&checker->secret_lock);
+ checker->secret_birthdate = ktime_get_boot_fast_ns();
+ get_random_bytes(checker->secret, NOISE_HASH_LEN);
+ up_write(&checker->secret_lock);
+ }
+
+ down_read(&checker->secret_lock);
+
+ blake2s_init_key(&state, COOKIE_LEN, checker->secret, NOISE_HASH_LEN);
+ if (skb->protocol == htons(ETH_P_IP))
+ blake2s_update(&state, (u8 *)&ip_hdr(skb)->saddr,
+ sizeof(struct in_addr));
+ else if (skb->protocol == htons(ETH_P_IPV6))
+ blake2s_update(&state, (u8 *)&ipv6_hdr(skb)->saddr,
+ sizeof(struct in6_addr));
+ blake2s_update(&state, (u8 *)&udp_hdr(skb)->source, sizeof(__be16));
+ blake2s_final(&state, cookie, COOKIE_LEN);
+
+ up_read(&checker->secret_lock);
+}
+
+enum cookie_mac_state wg_cookie_validate_packet(struct cookie_checker *checker,
+ struct sk_buff *skb,
+ bool check_cookie)
+{
+ struct message_macs *macs = (struct message_macs *)
+ (skb->data + skb->len - sizeof(*macs));
+ enum cookie_mac_state ret;
+ u8 computed_mac[COOKIE_LEN];
+ u8 cookie[COOKIE_LEN];
+
+ ret = INVALID_MAC;
+ compute_mac1(computed_mac, skb->data, skb->len,
+ checker->message_mac1_key);
+ if (crypto_memneq(computed_mac, macs->mac1, COOKIE_LEN))
+ goto out;
+
+ ret = VALID_MAC_BUT_NO_COOKIE;
+
+ if (!check_cookie)
+ goto out;
+
+ make_cookie(cookie, skb, checker);
+
+ compute_mac2(computed_mac, skb->data, skb->len, cookie);
+ if (crypto_memneq(computed_mac, macs->mac2, COOKIE_LEN))
+ goto out;
+
+ ret = VALID_MAC_WITH_COOKIE_BUT_RATELIMITED;
+ if (!wg_ratelimiter_allow(skb, dev_net(checker->device->dev)))
+ goto out;
+
+ ret = VALID_MAC_WITH_COOKIE;
+
+out:
+ return ret;
+}
+
+void wg_cookie_add_mac_to_packet(void *message, size_t len,
+ struct wg_peer *peer)
+{
+ struct message_macs *macs = (struct message_macs *)
+ ((u8 *)message + len - sizeof(*macs));
+
+ down_write(&peer->latest_cookie.lock);
+ compute_mac1(macs->mac1, message, len,
+ peer->latest_cookie.message_mac1_key);
+ memcpy(peer->latest_cookie.last_mac1_sent, macs->mac1, COOKIE_LEN);
+ peer->latest_cookie.have_sent_mac1 = true;
+ up_write(&peer->latest_cookie.lock);
+
+ down_read(&peer->latest_cookie.lock);
+ if (peer->latest_cookie.is_valid &&
+ !wg_birthdate_has_expired(peer->latest_cookie.birthdate,
+ COOKIE_SECRET_MAX_AGE - COOKIE_SECRET_LATENCY))
+ compute_mac2(macs->mac2, message, len,
+ peer->latest_cookie.cookie);
+ else
+ memset(macs->mac2, 0, COOKIE_LEN);
+ up_read(&peer->latest_cookie.lock);
+}
+
+void wg_cookie_message_create(struct message_handshake_cookie *dst,
+ struct sk_buff *skb, __le32 index,
+ struct cookie_checker *checker)
+{
+ struct message_macs *macs = (struct message_macs *)
+ ((u8 *)skb->data + skb->len - sizeof(*macs));
+ u8 cookie[COOKIE_LEN];
+
+ dst->header.type = cpu_to_le32(MESSAGE_HANDSHAKE_COOKIE);
+ dst->receiver_index = index;
+ get_random_bytes_wait(dst->nonce, COOKIE_NONCE_LEN);
+
+ make_cookie(cookie, skb, checker);
+ xchacha20poly1305_encrypt(dst->encrypted_cookie, cookie, COOKIE_LEN,
+ macs->mac1, COOKIE_LEN, dst->nonce,
+ checker->cookie_encryption_key);
+}
+
+void wg_cookie_message_consume(struct message_handshake_cookie *src,
+ struct wg_device *wg)
+{
+ struct wg_peer *peer = NULL;
+ u8 cookie[COOKIE_LEN];
+ bool ret;
+
+ if (unlikely(!wg_index_hashtable_lookup(wg->index_hashtable,
+ INDEX_HASHTABLE_HANDSHAKE |
+ INDEX_HASHTABLE_KEYPAIR,
+ src->receiver_index, &peer)))
+ return;
+
+ down_read(&peer->latest_cookie.lock);
+ if (unlikely(!peer->latest_cookie.have_sent_mac1)) {
+ up_read(&peer->latest_cookie.lock);
+ goto out;
+ }
+ ret = xchacha20poly1305_decrypt(
+ cookie, src->encrypted_cookie, sizeof(src->encrypted_cookie),
+ peer->latest_cookie.last_mac1_sent, COOKIE_LEN, src->nonce,
+ peer->latest_cookie.cookie_decryption_key);
+ up_read(&peer->latest_cookie.lock);
+
+ if (ret) {
+ down_write(&peer->latest_cookie.lock);
+ memcpy(peer->latest_cookie.cookie, cookie, COOKIE_LEN);
+ peer->latest_cookie.birthdate = ktime_get_boot_fast_ns();
+ peer->latest_cookie.is_valid = true;
+ peer->latest_cookie.have_sent_mac1 = false;
+ up_write(&peer->latest_cookie.lock);
+ } else {
+ net_dbg_ratelimited("%s: Could not decrypt invalid cookie response\n",
+ wg->dev->name);
+ }
+
+out:
+ wg_peer_put(peer);
+}