1 /* $OpenBSD: kexgexc.c,v 1.20 2015/01/26 06:10:03 djm Exp $ */
3 * Copyright (c) 2000 Niels Provos. All rights reserved.
4 * Copyright (c) 2001 Markus Friedl. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 #include <sys/types.h>
33 #include <openssl/dh.h>
53 static int input_kex_dh_gex_group(int, u_int32_t, void *);
54 static int input_kex_dh_gex_reply(int, u_int32_t, void *);
57 kexgex_client(struct ssh *ssh)
59 struct kex *kex = ssh->kex;
63 nbits = dh_estimate(kex->dh_need * 8);
65 kex->min = DH_GRP_MIN;
66 kex->max = DH_GRP_MAX;
68 if (ssh->compat & SSH_OLD_DHGEX) {
70 if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST_OLD))
72 (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
73 (r = sshpkt_send(ssh)) != 0)
75 debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", kex->nbits);
78 if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_REQUEST)) != 0 ||
79 (r = sshpkt_put_u32(ssh, kex->min)) != 0 ||
80 (r = sshpkt_put_u32(ssh, kex->nbits)) != 0 ||
81 (r = sshpkt_put_u32(ssh, kex->max)) != 0 ||
82 (r = sshpkt_send(ssh)) != 0)
84 debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
85 kex->min, kex->nbits, kex->max);
88 fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
89 kex->min, kex->nbits, kex->max);
91 ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP,
92 &input_kex_dh_gex_group);
99 input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt)
101 struct ssh *ssh = ctxt;
102 struct kex *kex = ssh->kex;
103 BIGNUM *p = NULL, *g = NULL;
106 debug("got SSH2_MSG_KEX_DH_GEX_GROUP");
108 if ((p = BN_new()) == NULL ||
109 (g = BN_new()) == NULL) {
110 r = SSH_ERR_ALLOC_FAIL;
113 if ((r = sshpkt_get_bignum2(ssh, p)) != 0 ||
114 (r = sshpkt_get_bignum2(ssh, g)) != 0 ||
115 (r = sshpkt_get_end(ssh)) != 0)
117 if ((bits = BN_num_bits(p)) < 0 ||
118 (u_int)bits < kex->min || (u_int)bits > kex->max) {
119 r = SSH_ERR_DH_GEX_OUT_OF_RANGE;
122 if ((kex->dh = dh_new_group(g, p)) == NULL) {
123 r = SSH_ERR_ALLOC_FAIL;
126 p = g = NULL; /* belong to kex->dh now */
128 /* generate and send 'e', client DH public key */
129 if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 ||
130 (r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 ||
131 (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 ||
132 (r = sshpkt_send(ssh)) != 0)
134 debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
136 DHparams_print_fp(stderr, kex->dh);
137 fprintf(stderr, "pub= ");
138 BN_print_fp(stderr, kex->dh->pub_key);
139 fprintf(stderr, "\n");
141 ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP, NULL);
142 ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REPLY, &input_kex_dh_gex_reply);
153 input_kex_dh_gex_reply(int type, u_int32_t seq, void *ctxt)
155 struct ssh *ssh = ctxt;
156 struct kex *kex = ssh->kex;
157 BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
158 struct sshkey *server_host_key = NULL;
159 u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL;
160 u_char hash[SSH_DIGEST_MAX_LENGTH];
161 size_t klen = 0, slen, sbloblen, hashlen;
164 debug("got SSH2_MSG_KEX_DH_GEX_REPLY");
165 if (kex->verify_host_key == NULL) {
166 r = SSH_ERR_INVALID_ARGUMENT;
170 if ((r = sshpkt_get_string(ssh, &server_host_key_blob,
172 (r = sshkey_from_blob(server_host_key_blob, sbloblen,
173 &server_host_key)) != 0)
175 if (server_host_key->type != kex->hostkey_type) {
176 r = SSH_ERR_KEY_TYPE_MISMATCH;
179 if (server_host_key->type != kex->hostkey_type ||
180 (kex->hostkey_type == KEY_ECDSA &&
181 server_host_key->ecdsa_nid != kex->hostkey_nid)) {
182 r = SSH_ERR_KEY_TYPE_MISMATCH;
185 if (kex->verify_host_key(server_host_key, ssh) == -1) {
186 r = SSH_ERR_SIGNATURE_INVALID;
189 /* DH parameter f, server public DH key */
190 if ((dh_server_pub = BN_new()) == NULL) {
191 r = SSH_ERR_ALLOC_FAIL;
195 if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 ||
196 (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 ||
197 (r = sshpkt_get_end(ssh)) != 0)
200 fprintf(stderr, "dh_server_pub= ");
201 BN_print_fp(stderr, dh_server_pub);
202 fprintf(stderr, "\n");
203 debug("bits %d", BN_num_bits(dh_server_pub));
205 if (!dh_pub_is_valid(kex->dh, dh_server_pub)) {
206 sshpkt_disconnect(ssh, "bad server public DH value");
207 r = SSH_ERR_MESSAGE_INCOMPLETE;
211 klen = DH_size(kex->dh);
212 if ((kbuf = malloc(klen)) == NULL ||
213 (shared_secret = BN_new()) == NULL) {
214 r = SSH_ERR_ALLOC_FAIL;
217 if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 ||
218 BN_bin2bn(kbuf, kout, shared_secret) == NULL) {
219 r = SSH_ERR_LIBCRYPTO_ERROR;
223 dump_digest("shared secret", kbuf, kout);
225 if (ssh->compat & SSH_OLD_DHGEX)
226 kex->min = kex->max = -1;
228 /* calc and verify H */
229 hashlen = sizeof(hash);
230 if ((r = kexgex_hash(
232 kex->client_version_string,
233 kex->server_version_string,
234 sshbuf_ptr(kex->my), sshbuf_len(kex->my),
235 sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
236 server_host_key_blob, sbloblen,
237 kex->min, kex->nbits, kex->max,
238 kex->dh->p, kex->dh->g,
242 hash, &hashlen)) != 0)
245 if ((r = sshkey_verify(server_host_key, signature, slen, hash,
246 hashlen, ssh->compat)) != 0)
249 /* save session id */
250 if (kex->session_id == NULL) {
251 kex->session_id_len = hashlen;
252 kex->session_id = malloc(kex->session_id_len);
253 if (kex->session_id == NULL) {
254 r = SSH_ERR_ALLOC_FAIL;
257 memcpy(kex->session_id, hash, kex->session_id_len);
260 if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0)
261 r = kex_send_newkeys(ssh);
263 explicit_bzero(hash, sizeof(hash));
267 BN_clear_free(dh_server_pub);
269 explicit_bzero(kbuf, klen);
273 BN_clear_free(shared_secret);
274 sshkey_free(server_host_key);
275 free(server_host_key_blob);
279 #endif /* WITH_OPENSSL */