summaryrefslogtreecommitdiff
path: root/kex.h
blob: fe71414140b33d2b97530d9fa4a9b175075784f2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
/* $OpenBSD: kex.h,v 1.109 2019/09/06 05:23:55 djm Exp $ */

/*
 * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef KEX_H
#define KEX_H

#include "mac.h"
#include "crypto_api.h"

#ifdef WITH_OPENSSL
# include <openssl/bn.h>
# include <openssl/dh.h>
# include <openssl/ecdsa.h>
# ifdef OPENSSL_HAS_ECC
#  include <openssl/ec.h>
# else /* OPENSSL_HAS_ECC */
#  define EC_KEY	void
#  define EC_GROUP	void
#  define EC_POINT	void
# endif /* OPENSSL_HAS_ECC */
#else /* WITH_OPENSSL */
# define DH		void
# define BIGNUM		void
# define EC_KEY		void
# define EC_GROUP	void
# define EC_POINT	void
#endif /* WITH_OPENSSL */

#define KEX_COOKIE_LEN	16

#define	KEX_DH1				"diffie-hellman-group1-sha1"
#define	KEX_DH14_SHA1			"diffie-hellman-group14-sha1"
#define	KEX_DH14_SHA256			"diffie-hellman-group14-sha256"
#define	KEX_DH16_SHA512			"diffie-hellman-group16-sha512"
#define	KEX_DH18_SHA512			"diffie-hellman-group18-sha512"
#define	KEX_DHGEX_SHA1			"diffie-hellman-group-exchange-sha1"
#define	KEX_DHGEX_SHA256		"diffie-hellman-group-exchange-sha256"
#define	KEX_ECDH_SHA2_NISTP256		"ecdh-sha2-nistp256"
#define	KEX_ECDH_SHA2_NISTP384		"ecdh-sha2-nistp384"
#define	KEX_ECDH_SHA2_NISTP521		"ecdh-sha2-nistp521"
#define	KEX_CURVE25519_SHA256		"curve25519-sha256"
#define	KEX_CURVE25519_SHA256_OLD	"curve25519-sha256@libssh.org"
#define	KEX_SNTRUP4591761X25519_SHA512	"sntrup4591761x25519-sha512@tinyssh.org"

#define COMP_NONE	0
/* pre-auth compression (COMP_ZLIB) is only supported in the client */
#define COMP_ZLIB	1
#define COMP_DELAYED	2

#define CURVE25519_SIZE 32

enum kex_init_proposals {
	PROPOSAL_KEX_ALGS,
	PROPOSAL_SERVER_HOST_KEY_ALGS,
	PROPOSAL_ENC_ALGS_CTOS,
	PROPOSAL_ENC_ALGS_STOC,
	PROPOSAL_MAC_ALGS_CTOS,
	PROPOSAL_MAC_ALGS_STOC,
	PROPOSAL_COMP_ALGS_CTOS,
	PROPOSAL_COMP_ALGS_STOC,
	PROPOSAL_LANG_CTOS,
	PROPOSAL_LANG_STOC,
	PROPOSAL_MAX
};

enum kex_modes {
	MODE_IN,
	MODE_OUT,
	MODE_MAX
};

enum kex_exchange {
	KEX_DH_GRP1_SHA1,
	KEX_DH_GRP14_SHA1,
	KEX_DH_GRP14_SHA256,
	KEX_DH_GRP16_SHA512,
	KEX_DH_GRP18_SHA512,
	KEX_DH_GEX_SHA1,
	KEX_DH_GEX_SHA256,
	KEX_ECDH_SHA2,
	KEX_C25519_SHA256,
	KEX_KEM_SNTRUP4591761X25519_SHA512,
#ifdef GSSAPI
	KEX_GSS_GRP1_SHA1,
	KEX_GSS_GRP14_SHA1,
	KEX_GSS_GRP14_SHA256,
	KEX_GSS_GRP16_SHA512,
	KEX_GSS_GEX_SHA1,
	KEX_GSS_NISTP256_SHA256,
	KEX_GSS_C25519_SHA256,
#endif
	KEX_MAX
};

#define KEX_INIT_SENT	0x0001
#define KEX_INITIAL	0x0002

struct sshenc {
	char	*name;
	const struct sshcipher *cipher;
	int	enabled;
	u_int	key_len;
	u_int	iv_len;
	u_int	block_size;
	u_char	*key;
	u_char	*iv;
};
struct sshcomp {
	u_int	type;
	int	enabled;
	char	*name;
};
struct newkeys {
	struct sshenc	enc;
	struct sshmac	mac;
	struct sshcomp  comp;
};

struct ssh;

struct kex {
	u_char	*session_id;
	size_t	session_id_len;
	struct newkeys	*newkeys[MODE_MAX];
	u_int	we_need;
	u_int	dh_need;
	int	server;
	char	*name;
	char	*hostkey_alg;
	int	hostkey_type;
	int	hostkey_nid;
	u_int	kex_type;
	char	*server_sig_algs;
	int	ext_info_c;
	struct sshbuf *my;
	struct sshbuf *peer;
	struct sshbuf *client_version;
	struct sshbuf *server_version;
	sig_atomic_t done;
	u_int	flags;
	int	hash_alg;
	int	ec_nid;
#ifdef GSSAPI
	int	gss_deleg_creds;
	int	gss_trust_dns;
	char    *gss_host;
	char	*gss_client;
#endif
	char	*failed_choice;
	int	(*verify_host_key)(struct sshkey *, struct ssh *);
	struct sshkey *(*load_host_public_key)(int, int, struct ssh *);
	struct sshkey *(*load_host_private_key)(int, int, struct ssh *);
	int	(*host_key_index)(struct sshkey *, int, struct ssh *);
	int	(*sign)(struct ssh *, struct sshkey *, struct sshkey *,
	    u_char **, size_t *, const u_char *, size_t, const char *);
	int	(*kex[KEX_MAX])(struct ssh *);
	/* kex specific state */
	DH	*dh;			/* DH */
	u_int	min, max, nbits;	/* GEX */
	EC_KEY	*ec_client_key;		/* ECDH */
	const EC_GROUP *ec_group;	/* ECDH */
	u_char c25519_client_key[CURVE25519_SIZE]; /* 25519 + KEM */
	u_char c25519_client_pubkey[CURVE25519_SIZE]; /* 25519 */
	u_char sntrup4591761_client_key[crypto_kem_sntrup4591761_SECRETKEYBYTES]; /* KEM */
	struct sshbuf *client_pub;
};

int	 kex_names_valid(const char *);
char	*kex_alg_list(char);
char	*kex_gss_alg_list(char);
char	*kex_names_cat(const char *, const char *);
int	 kex_assemble_names(char **, const char *, const char *);
int	 kex_gss_names_valid(const char *);

int	 kex_exchange_identification(struct ssh *, int, const char *);

struct kex *kex_new(void);
int	 kex_ready(struct ssh *, char *[PROPOSAL_MAX]);
int	 kex_setup(struct ssh *, char *[PROPOSAL_MAX]);
void	 kex_free_newkeys(struct newkeys *);
void	 kex_free(struct kex *);

int	 kex_buf2prop(struct sshbuf *, int *, char ***);
int	 kex_prop2buf(struct sshbuf *, char *proposal[PROPOSAL_MAX]);
void	 kex_prop_free(char **);
int	 kex_load_hostkey(struct ssh *, struct sshkey **, struct sshkey **);
int	 kex_verify_host_key(struct ssh *, struct sshkey *);

int	 kex_send_kexinit(struct ssh *);
int	 kex_input_kexinit(int, u_int32_t, struct ssh *);
int	 kex_input_ext_info(int, u_int32_t, struct ssh *);
int	 kex_derive_keys(struct ssh *, u_char *, u_int, const struct sshbuf *);
int	 kex_send_newkeys(struct ssh *);
int	 kex_start_rekex(struct ssh *);

int	 kexgex_client(struct ssh *);
int	 kexgex_server(struct ssh *);
int	 kex_gen_client(struct ssh *);
int	 kex_gen_server(struct ssh *);
#if defined(GSSAPI) && defined(WITH_OPENSSL)
int	 kexgssgex_client(struct ssh *);
int	 kexgssgex_server(struct ssh *);
int	 kexgss_client(struct ssh *);
int	 kexgss_server(struct ssh *);
#endif

int	 kex_dh_keypair(struct kex *);
int	 kex_dh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
    struct sshbuf **);
int	 kex_dh_dec(struct kex *, const struct sshbuf *, struct sshbuf **);

int	 kex_ecdh_keypair(struct kex *);
int	 kex_ecdh_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
    struct sshbuf **);
int	 kex_ecdh_dec(struct kex *, const struct sshbuf *, struct sshbuf **);

int	 kex_c25519_keypair(struct kex *);
int	 kex_c25519_enc(struct kex *, const struct sshbuf *, struct sshbuf **,
    struct sshbuf **);
int	 kex_c25519_dec(struct kex *, const struct sshbuf *, struct sshbuf **);

int	 kex_kem_sntrup4591761x25519_keypair(struct kex *);
int	 kex_kem_sntrup4591761x25519_enc(struct kex *, const struct sshbuf *,
    struct sshbuf **, struct sshbuf **);
int	 kex_kem_sntrup4591761x25519_dec(struct kex *, const struct sshbuf *,
    struct sshbuf **);

int	 kex_dh_keygen(struct kex *);
int	 kex_dh_compute_key(struct kex *, BIGNUM *, struct sshbuf *);

int	 kexgex_hash(int, const struct sshbuf *, const struct sshbuf *,
    const struct sshbuf *, const struct sshbuf *, const struct sshbuf *,
    int, int, int,
    const BIGNUM *, const BIGNUM *, const BIGNUM *,
    const BIGNUM *, const u_char *, size_t,
    u_char *, size_t *);

int	 kex_gen_hash(int hash_alg, const struct sshbuf *client_version,
    const struct sshbuf *server_version, const struct sshbuf *client_kexinit,
    const struct sshbuf *server_kexinit, const struct sshbuf *server_host_key_blob,
    const struct sshbuf *client_pub, const struct sshbuf *server_pub,
    const struct sshbuf *shared_secret, u_char *hash, size_t *hashlen);

void	kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
	__attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
	__attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
int	kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
    const u_char pub[CURVE25519_SIZE], struct sshbuf *out)
	__attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
	__attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));
int	kexc25519_shared_key_ext(const u_char key[CURVE25519_SIZE],
    const u_char pub[CURVE25519_SIZE], struct sshbuf *out, int)
	__attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
	__attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)));

#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
void	dump_digest(const char *, const u_char *, int);
#endif

#if !defined(WITH_OPENSSL) || !defined(OPENSSL_HAS_ECC)
# undef EC_KEY
# undef EC_GROUP
# undef EC_POINT
#endif

#endif