1/* $OpenBSD: wg_cookie.h,v 1.2 2020/12/09 05:53:33 tb Exp $ */
2/*
3 * Copyright (C) 2015-2020 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 * Copyright (C) 2019-2020 Matt Dunwoodie <ncon@noconroy.net>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#ifndef __COOKIE_H__
20#define __COOKIE_H__
21
22#include <sys/types.h>
23#include <sys/time.h>
24#include <sys/rwlock.h>
25#include <sys/queue.h>
26
27#include <netinet/in.h>
28
29#include <crypto/chachapoly.h>
30#include <crypto/blake2s.h>
31#include <crypto/siphash.h>
32
33#define COOKIE_MAC_SIZE 16
34#define COOKIE_KEY_SIZE 32
35#define COOKIE_NONCE_SIZE XCHACHA20POLY1305_NONCE_SIZE
36#define COOKIE_COOKIE_SIZE 16
37#define COOKIE_SECRET_SIZE 32
38#define COOKIE_INPUT_SIZE 32
39#define COOKIE_ENCRYPTED_SIZE (COOKIE_COOKIE_SIZE + COOKIE_MAC_SIZE)
40
41#define COOKIE_MAC1_KEY_LABEL "mac1----"
42#define COOKIE_COOKIE_KEY_LABEL "cookie--"
43#define COOKIE_SECRET_MAX_AGE 120
44#define COOKIE_SECRET_LATENCY 5
45
46/* Constants for initiation rate limiting */
47#define RATELIMIT_SIZE (1 << 13)
48#define RATELIMIT_SIZE_MAX (RATELIMIT_SIZE * 8)
49#define NSEC_PER_SEC 1000000000LL
50#define INITIATIONS_PER_SECOND 20
51#define INITIATIONS_BURSTABLE 5
52#define INITIATION_COST (NSEC_PER_SEC / INITIATIONS_PER_SECOND)
53#define TOKEN_MAX (INITIATION_COST * INITIATIONS_BURSTABLE)
54#define ELEMENT_TIMEOUT 1
55#define IPV4_MASK_SIZE 4 /* Use all 4 bytes of IPv4 address */
56#define IPV6_MASK_SIZE 8 /* Use top 8 bytes (/64) of IPv6 address */
57
58struct cookie_macs {
59 uint8_t mac1[COOKIE_MAC_SIZE];
60 uint8_t mac2[COOKIE_MAC_SIZE];
61};
62
63struct ratelimit_entry {
64 LIST_ENTRY(ratelimit_entry) r_entry;
65 sa_family_t r_af;
66 union {
67 struct in_addr r_in;
68#ifdef INET6
69 struct in6_addr r_in6;
70#endif
71 };
72 struct timespec r_last_time; /* nanouptime */
73 uint64_t r_tokens;
74};
75
76struct ratelimit {
77 SIPHASH_KEY rl_secret;
78 struct pool *rl_pool;
79
80 struct rwlock rl_lock;
81 LIST_HEAD(, ratelimit_entry) *rl_table;
82 u_long rl_table_mask;
83 size_t rl_table_num;
84 struct timespec rl_last_gc; /* nanouptime */
85};
86
87struct cookie_maker {
88 uint8_t cp_mac1_key[COOKIE_KEY_SIZE];
89 uint8_t cp_cookie_key[COOKIE_KEY_SIZE];
90
91 struct rwlock cp_lock;
92 uint8_t cp_cookie[COOKIE_COOKIE_SIZE];
93 struct timespec cp_birthdate; /* nanouptime */
94 int cp_mac1_valid;
95 uint8_t cp_mac1_last[COOKIE_MAC_SIZE];
96};
97
98struct cookie_checker {
99 struct ratelimit cc_ratelimit_v4;
100#ifdef INET6
101 struct ratelimit cc_ratelimit_v6;
102#endif
103
104 struct rwlock cc_key_lock;
105 uint8_t cc_mac1_key[COOKIE_KEY_SIZE];
106 uint8_t cc_cookie_key[COOKIE_KEY_SIZE];
107
108 struct rwlock cc_secret_lock;
109 struct timespec cc_secret_birthdate; /* nanouptime */
110 uint8_t cc_secret[COOKIE_SECRET_SIZE];
111};
112
113void cookie_maker_init(struct cookie_maker *, uint8_t[COOKIE_INPUT_SIZE]);
114int cookie_checker_init(struct cookie_checker *, struct pool *);
115void cookie_checker_update(struct cookie_checker *,
116 uint8_t[COOKIE_INPUT_SIZE]);
117void cookie_checker_deinit(struct cookie_checker *);
118void cookie_checker_create_payload(struct cookie_checker *,
119 struct cookie_macs *cm, uint8_t[COOKIE_NONCE_SIZE],
120 uint8_t [COOKIE_ENCRYPTED_SIZE], struct sockaddr *);
121int cookie_maker_consume_payload(struct cookie_maker *,
122 uint8_t[COOKIE_NONCE_SIZE], uint8_t[COOKIE_ENCRYPTED_SIZE]);
123void cookie_maker_mac(struct cookie_maker *, struct cookie_macs *,
124 void *, size_t);
125int cookie_checker_validate_macs(struct cookie_checker *,
126 struct cookie_macs *, void *, size_t, int, struct sockaddr *);
127
128#ifdef WGTEST
129void cookie_test();
130#endif /* WGTEST */
131
132#endif /* __COOKIE_H__ */