roaming_client.c revision 255767 
1/* $OpenBSD: roaming_client.c,v 1.5 2013/05/17 00:13:14 djm Exp $ */
2/*
3 * Copyright (c) 2004-2009 AppGate Network Security AB
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include "includes.h"
19
20#include "openbsd-compat/sys-queue.h"
21#include <sys/types.h>
22#include <sys/socket.h>
23
24#ifdef HAVE_INTTYPES_H
25#include <inttypes.h>
26#endif
27#include <signal.h>
28#include <string.h>
29#include <unistd.h>
30
31#include <openssl/crypto.h>
32#include <openssl/sha.h>
33
34#include "xmalloc.h"
35#include "buffer.h"
36#include "channels.h"
37#include "cipher.h"
38#include "dispatch.h"
39#include "clientloop.h"
40#include "log.h"
41#include "match.h"
42#include "misc.h"
43#include "packet.h"
44#include "ssh.h"
45#include "key.h"
46#include "kex.h"
47#include "readconf.h"
48#include "roaming.h"
49#include "ssh2.h"
50#include "sshconnect.h"
51
52/* import */
53extern Options options;
54extern char *host;
55extern struct sockaddr_storage hostaddr;
56extern int session_resumed;
57
58static u_int32_t roaming_id;
59static u_int64_t cookie;
60static u_int64_t lastseenchall;
61static u_int64_t key1, key2, oldkey1, oldkey2;
62
63void
64roaming_reply(int type, u_int32_t seq, void *ctxt)
65{
66	if (type == SSH2_MSG_REQUEST_FAILURE) {
67		logit("Server denied roaming");
68		return;
69	}
70	verbose("Roaming enabled");
71	roaming_id = packet_get_int();
72	cookie = packet_get_int64();
73	key1 = oldkey1 = packet_get_int64();
74	key2 = oldkey2 = packet_get_int64();
75	set_out_buffer_size(packet_get_int() + get_snd_buf_size());
76	roaming_enabled = 1;
77}
78
79void
80request_roaming(void)
81{
82	packet_start(SSH2_MSG_GLOBAL_REQUEST);
83	packet_put_cstring(ROAMING_REQUEST);
84	packet_put_char(1);
85	packet_put_int(get_recv_buf_size());
86	packet_send();
87	client_register_global_confirm(roaming_reply, NULL);
88}
89
90static void
91roaming_auth_required(void)
92{
93	u_char digest[SHA_DIGEST_LENGTH];
94	EVP_MD_CTX md;
95	Buffer b;
96	const EVP_MD *evp_md = EVP_sha1();
97	u_int64_t chall, oldchall;
98
99	chall = packet_get_int64();
100	oldchall = packet_get_int64();
101	if (oldchall != lastseenchall) {
102		key1 = oldkey1;
103		key2 = oldkey2;
104	}
105	lastseenchall = chall;
106
107	buffer_init(&b);
108	buffer_put_int64(&b, cookie);
109	buffer_put_int64(&b, chall);
110	EVP_DigestInit(&md, evp_md);
111	EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
112	EVP_DigestFinal(&md, digest, NULL);
113	buffer_free(&b);
114
115	packet_start(SSH2_MSG_KEX_ROAMING_AUTH);
116	packet_put_int64(key1 ^ get_recv_bytes());
117	packet_put_raw(digest, sizeof(digest));
118	packet_send();
119
120	oldkey1 = key1;
121	oldkey2 = key2;
122	calculate_new_key(&key1, cookie, chall);
123	calculate_new_key(&key2, cookie, chall);
124
125	debug("Received %llu bytes", (unsigned long long)get_recv_bytes());
126	debug("Sent roaming_auth packet");
127}
128
129int
130resume_kex(void)
131{
132	/*
133	 * This should not happen - if the client sends the kex method
134	 * resume@appgate.com then the kex is done in roaming_resume().
135	 */
136	return 1;
137}
138
139static int
140roaming_resume(void)
141{
142	u_int64_t recv_bytes;
143	char *str = NULL, *kexlist = NULL, *c;
144	int i, type;
145	int timeout_ms = options.connection_timeout * 1000;
146	u_int len;
147	u_int32_t rnd = 0;
148
149	resume_in_progress = 1;
150
151	/* Exchange banners */
152	ssh_exchange_identification(timeout_ms);
153	packet_set_nonblocking();
154
155	/* Send a kexinit message with resume@appgate.com as only kex algo */
156	packet_start(SSH2_MSG_KEXINIT);
157	for (i = 0; i < KEX_COOKIE_LEN; i++) {
158		if (i % 4 == 0)
159			rnd = arc4random();
160		packet_put_char(rnd & 0xff);
161		rnd >>= 8;
162	}
163	packet_put_cstring(KEX_RESUME);
164	for (i = 1; i < PROPOSAL_MAX; i++) {
165		/* kex algorithm added so start with i=1 and not 0 */
166		packet_put_cstring(""); /* Not used when we resume */
167	}
168	packet_put_char(1); /* first kex_packet follows */
169	packet_put_int(0); /* reserved */
170	packet_send();
171
172	/* Assume that resume@appgate.com will be accepted */
173	packet_start(SSH2_MSG_KEX_ROAMING_RESUME);
174	packet_put_int(roaming_id);
175	packet_send();
176
177	/* Read the server's kexinit and check for resume@appgate.com */
178	if ((type = packet_read()) != SSH2_MSG_KEXINIT) {
179		debug("expected kexinit on resume, got %d", type);
180		goto fail;
181	}
182	for (i = 0; i < KEX_COOKIE_LEN; i++)
183		(void)packet_get_char();
184	kexlist = packet_get_string(&len);
185	if (!kexlist
186	    || (str = match_list(KEX_RESUME, kexlist, NULL)) == NULL) {
187		debug("server doesn't allow resume");
188		goto fail;
189	}
190	free(str);
191	for (i = 1; i < PROPOSAL_MAX; i++) {
192		/* kex algorithm taken care of so start with i=1 and not 0 */
193		free(packet_get_string(&len));
194	}
195	i = packet_get_char(); /* first_kex_packet_follows */
196	if (i && (c = strchr(kexlist, ',')))
197		*c = 0;
198	if (i && strcmp(kexlist, KEX_RESUME)) {
199		debug("server's kex guess (%s) was wrong, skipping", kexlist);
200		(void)packet_read(); /* Wrong guess - discard packet */
201	}
202
203	/*
204	 * Read the ROAMING_AUTH_REQUIRED challenge from the server and
205	 * send ROAMING_AUTH
206	 */
207	if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_REQUIRED) {
208		debug("expected roaming_auth_required, got %d", type);
209		goto fail;
210	}
211	roaming_auth_required();
212
213	/* Read ROAMING_AUTH_OK from the server */
214	if ((type = packet_read()) != SSH2_MSG_KEX_ROAMING_AUTH_OK) {
215		debug("expected roaming_auth_ok, got %d", type);
216		goto fail;
217	}
218	recv_bytes = packet_get_int64() ^ oldkey2;
219	debug("Peer received %llu bytes", (unsigned long long)recv_bytes);
220	resend_bytes(packet_get_connection_out(), &recv_bytes);
221
222	resume_in_progress = 0;
223
224	session_resumed = 1; /* Tell clientloop */
225
226	return 0;
227
228fail:
229	free(kexlist);
230	if (packet_get_connection_in() == packet_get_connection_out())
231		close(packet_get_connection_in());
232	else {
233		close(packet_get_connection_in());
234		close(packet_get_connection_out());
235	}
236	return 1;
237}
238
239int
240wait_for_roaming_reconnect(void)
241{
242	static int reenter_guard = 0;
243	int timeout_ms = options.connection_timeout * 1000;
244	int c;
245
246	if (reenter_guard != 0)
247		fatal("Server refused resume, roaming timeout may be exceeded");
248	reenter_guard = 1;
249
250	fprintf(stderr, "[connection suspended, press return to resume]");
251	fflush(stderr);
252	packet_backup_state();
253	/* TODO Perhaps we should read from tty here */
254	while ((c = fgetc(stdin)) != EOF) {
255		if (c == 'Z' - 64) {
256			kill(getpid(), SIGTSTP);
257			continue;
258		}
259		if (c != '\n' && c != '\r')
260			continue;
261
262		if (ssh_connect(host, &hostaddr, options.port,
263		    options.address_family, 1, &timeout_ms,
264		    options.tcp_keep_alive, options.use_privileged_port,
265		    options.proxy_command) == 0 && roaming_resume() == 0) {
266			packet_restore_state();
267			reenter_guard = 0;
268			fprintf(stderr, "[connection resumed]\n");
269			fflush(stderr);
270			return 0;
271		}
272
273		fprintf(stderr, "[reconnect failed, press return to retry]");
274		fflush(stderr);
275	}
276	fprintf(stderr, "[exiting]\n");
277	fflush(stderr);
278	exit(0);
279}
280