1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  4 */
  5
  6#ifndef _WG_MESSAGES_H
  7#define _WG_MESSAGES_H
  8
  9#include <crypto/curve25519.h>
 10#include <crypto/chacha20poly1305.h>
 11#include <crypto/blake2s.h>
 12
 13#include <linux/kernel.h>
 14#include <linux/param.h>
 15#include <linux/skbuff.h>
 16
 17enum noise_lengths {
 18	NOISE_PUBLIC_KEY_LEN = CURVE25519_KEY_SIZE,
 19	NOISE_SYMMETRIC_KEY_LEN = CHACHA20POLY1305_KEY_SIZE,
 20	NOISE_TIMESTAMP_LEN = sizeof(u64) + sizeof(u32),
 21	NOISE_AUTHTAG_LEN = CHACHA20POLY1305_AUTHTAG_SIZE,
 22	NOISE_HASH_LEN = BLAKE2S_HASH_SIZE
 23};
 24
 25#define noise_encrypted_len(plain_len) ((plain_len) + NOISE_AUTHTAG_LEN)
 26
 27enum cookie_values {
 28	COOKIE_SECRET_MAX_AGE = 2 * 60,
 29	COOKIE_SECRET_LATENCY = 5,
 30	COOKIE_NONCE_LEN = XCHACHA20POLY1305_NONCE_SIZE,
 31	COOKIE_LEN = 16
 32};
 33
 34enum counter_values {
 35	COUNTER_BITS_TOTAL = 8192,
 36	COUNTER_REDUNDANT_BITS = BITS_PER_LONG,
 37	COUNTER_WINDOW_SIZE = COUNTER_BITS_TOTAL - COUNTER_REDUNDANT_BITS
 38};
 39
 40enum limits {
 41	REKEY_AFTER_MESSAGES = 1ULL << 60,
 42	REJECT_AFTER_MESSAGES = U64_MAX - COUNTER_WINDOW_SIZE - 1,
 43	REKEY_TIMEOUT = 5,
 44	REKEY_TIMEOUT_JITTER_MAX_JIFFIES = HZ / 3,
 45	REKEY_AFTER_TIME = 120,
 46	REJECT_AFTER_TIME = 180,
 47	INITIATIONS_PER_SECOND = 50,
 48	MAX_PEERS_PER_DEVICE = 1U << 20,
 49	KEEPALIVE_TIMEOUT = 10,
 50	MAX_TIMER_HANDSHAKES = 90 / REKEY_TIMEOUT,
 51	MAX_QUEUED_INCOMING_HANDSHAKES = 4096, /* TODO: replace this with DQL */
 52	MAX_STAGED_PACKETS = 128,
 53	MAX_QUEUED_PACKETS = 1024 /* TODO: replace this with DQL */
 54};
 55
 56enum message_type {
 57	MESSAGE_INVALID = 0,
 58	MESSAGE_HANDSHAKE_INITIATION = 1,
 59	MESSAGE_HANDSHAKE_RESPONSE = 2,
 60	MESSAGE_HANDSHAKE_COOKIE = 3,
 61	MESSAGE_DATA = 4
 62};
 63
 64struct message_header {
 65	/* The actual layout of this that we want is:
 66	 * u8 type
 67	 * u8 reserved_zero[3]
 68	 *
 69	 * But it turns out that by encoding this as little endian,
 70	 * we achieve the same thing, and it makes checking faster.
 71	 */
 72	__le32 type;
 73};
 74
 75struct message_macs {
 76	u8 mac1[COOKIE_LEN];
 77	u8 mac2[COOKIE_LEN];
 78};
 79
 80struct message_handshake_initiation {
 81	struct message_header header;
 82	__le32 sender_index;
 83	u8 unencrypted_ephemeral[NOISE_PUBLIC_KEY_LEN];
 84	u8 encrypted_static[noise_encrypted_len(NOISE_PUBLIC_KEY_LEN)];
 85	u8 encrypted_timestamp[noise_encrypted_len(NOISE_TIMESTAMP_LEN)];
 86	struct message_macs macs;
 87};
 88
 89struct message_handshake_response {
 90	struct message_header header;
 91	__le32 sender_index;
 92	__le32 receiver_index;
 93	u8 unencrypted_ephemeral[NOISE_PUBLIC_KEY_LEN];
 94	u8 encrypted_nothing[noise_encrypted_len(0)];
 95	struct message_macs macs;
 96};
 97
 98struct message_handshake_cookie {
 99	struct message_header header;
100	__le32 receiver_index;
101	u8 nonce[COOKIE_NONCE_LEN];
102	u8 encrypted_cookie[noise_encrypted_len(COOKIE_LEN)];
103};
104
105struct message_data {
106	struct message_header header;
107	__le32 key_idx;
108	__le64 counter;
109	u8 encrypted_data[];
110};
111
112#define message_data_len(plain_len) \
113	(noise_encrypted_len(plain_len) + sizeof(struct message_data))
114
115enum message_alignments {
116	MESSAGE_PADDING_MULTIPLE = 16,
117	MESSAGE_MINIMUM_LENGTH = message_data_len(0)
118};
119
120#define SKB_HEADER_LEN                                       \
121	(max(sizeof(struct iphdr), sizeof(struct ipv6hdr)) + \
122	 sizeof(struct udphdr) + NET_SKB_PAD)
123#define DATA_PACKET_HEAD_ROOM \
124	ALIGN(sizeof(struct message_data) + SKB_HEADER_LEN, 4)
125
126enum { HANDSHAKE_DSCP = 0x88 /* AF41, plus 00 ECN */ };
127
128#endif /* _WG_MESSAGES_H */