compat.c revision 323136 
1/* $OpenBSD: compat.c,v 1.100 2017/02/03 23:01:19 djm Exp $ */
2/*
3 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
27
28#include <sys/types.h>
29
30#include <stdlib.h>
31#include <string.h>
32#include <stdarg.h>
33
34#include "xmalloc.h"
35#include "buffer.h"
36#include "packet.h"
37#include "compat.h"
38#include "log.h"
39#include "match.h"
40#include "kex.h"
41
42int compat13 = 0;
43int compat20 = 0;
44int datafellows = 0;
45
46void
47enable_compat20(void)
48{
49	if (compat20)
50		return;
51	debug("Enabling compatibility mode for protocol 2.0");
52	compat20 = 1;
53}
54void
55enable_compat13(void)
56{
57	debug("Enabling compatibility mode for protocol 1.3");
58	compat13 = 1;
59}
60/* datafellows bug compatibility */
61u_int
62compat_datafellows(const char *version)
63{
64	int i;
65	static struct {
66		char	*pat;
67		int	bugs;
68	} check[] = {
69		{ "OpenSSH-2.0*,"
70		  "OpenSSH-2.1*,"
71		  "OpenSSH_2.1*,"
72		  "OpenSSH_2.2*",	SSH_OLD_SESSIONID|SSH_BUG_BANNER|
73					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
74					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
75		{ "OpenSSH_2.3.0*",	SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES|
76					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
77					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
78		{ "OpenSSH_2.3.*",	SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
79					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
80					SSH_OLD_FORWARD_ADDR},
81		{ "OpenSSH_2.5.0p1*,"
82		  "OpenSSH_2.5.1p1*",
83					SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
84					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
85					SSH_OLD_FORWARD_ADDR},
86		{ "OpenSSH_2.5.0*,"
87		  "OpenSSH_2.5.1*,"
88		  "OpenSSH_2.5.2*",	SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
89					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
90		{ "OpenSSH_2.5.3*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
91					SSH_OLD_FORWARD_ADDR},
92		{ "OpenSSH_2.*,"
93		  "OpenSSH_3.0*,"
94		  "OpenSSH_3.1*",	SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
95		{ "OpenSSH_3.*",	SSH_OLD_FORWARD_ADDR },
96		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
97		{ "OpenSSH_4*",		0 },
98		{ "OpenSSH_5*",		SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
99		{ "OpenSSH_6.6.1*",	SSH_NEW_OPENSSH},
100		{ "OpenSSH_6.5*,"
101		  "OpenSSH_6.6*",	SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
102		{ "OpenSSH*",		SSH_NEW_OPENSSH },
103		{ "*MindTerm*",		0 },
104		{ "2.1.0*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
105					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
106					SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
107					SSH_BUG_FIRSTKEX },
108		{ "2.1 *",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
109					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
110					SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
111					SSH_BUG_FIRSTKEX },
112		{ "2.0.13*,"
113		  "2.0.14*,"
114		  "2.0.15*,"
115		  "2.0.16*,"
116		  "2.0.17*,"
117		  "2.0.18*,"
118		  "2.0.19*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
119					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
120					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
121					SSH_BUG_PKOK|SSH_BUG_RSASIGMD5|
122					SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE|
123					SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
124		{ "2.0.11*,"
125		  "2.0.12*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
126					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
127					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
128					SSH_BUG_PKAUTH|SSH_BUG_PKOK|
129					SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
130					SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
131		{ "2.0.*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
132					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
133					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
134					SSH_BUG_PKAUTH|SSH_BUG_PKOK|
135					SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
136					SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN|
137					SSH_BUG_FIRSTKEX },
138		{ "2.2.0*,"
139		  "2.3.0*",		SSH_BUG_HMAC|SSH_BUG_DEBUG|
140					SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX },
141		{ "2.3.*",		SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5|
142					SSH_BUG_FIRSTKEX },
143		{ "2.4",		SSH_OLD_SESSIONID },	/* Van Dyke */
144		{ "2.*",		SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX|
145					SSH_BUG_RFWD_ADDR },
146		{ "3.0.*",		SSH_BUG_DEBUG },
147		{ "3.0 SecureCRT*",	SSH_OLD_SESSIONID },
148		{ "1.7 SecureFX*",	SSH_OLD_SESSIONID },
149		{ "1.2.18*,"
150		  "1.2.19*,"
151		  "1.2.20*,"
152		  "1.2.21*,"
153		  "1.2.22*",		SSH_BUG_IGNOREMSG },
154		{ "1.3.2*",		/* F-Secure */
155					SSH_BUG_IGNOREMSG },
156		{ "Cisco-1.*",		SSH_BUG_DHGEX_LARGE|
157					SSH_BUG_HOSTKEYS },
158		{ "*SSH Compatible Server*",			/* Netscreen */
159					SSH_BUG_PASSWORDPAD },
160		{ "*OSU_0*,"
161		  "OSU_1.0*,"
162		  "OSU_1.1*,"
163		  "OSU_1.2*,"
164		  "OSU_1.3*,"
165		  "OSU_1.4*,"
166		  "OSU_1.5alpha1*,"
167		  "OSU_1.5alpha2*,"
168		  "OSU_1.5alpha3*",	SSH_BUG_PASSWORDPAD },
169		{ "*SSH_Version_Mapper*",
170					SSH_BUG_SCANNER },
171		{ "PuTTY_Local:*,"	/* dev versions < Sep 2014 */
172		  "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
173		  "PuTTY_Release_0.5*,"	/* 0.58-0.59 */
174		  "PuTTY_Release_0.60*,"
175		  "PuTTY_Release_0.61*,"
176		  "PuTTY_Release_0.62*,"
177		  "PuTTY_Release_0.63*,"
178		  "PuTTY_Release_0.64*",
179					SSH_OLD_DHGEX },
180		{ "FuTTY*",		SSH_OLD_DHGEX }, /* Putty Fork */
181		{ "Probe-*",
182					SSH_BUG_PROBE },
183		{ "TeraTerm SSH*,"
184		  "TTSSH/1.5.*,"
185		  "TTSSH/2.1*,"
186		  "TTSSH/2.2*,"
187		  "TTSSH/2.3*,"
188		  "TTSSH/2.4*,"
189		  "TTSSH/2.5*,"
190		  "TTSSH/2.6*,"
191		  "TTSSH/2.70*,"
192		  "TTSSH/2.71*,"
193		  "TTSSH/2.72*",	SSH_BUG_HOSTKEYS },
194		{ "WinSCP_release_4*,"
195		  "WinSCP_release_5.0*,"
196		  "WinSCP_release_5.1*,"
197		  "WinSCP_release_5.5*,"
198		  "WinSCP_release_5.6*,"
199		  "WinSCP_release_5.7,"
200		  "WinSCP_release_5.7.1,"
201		  "WinSCP_release_5.7.2,"
202		  "WinSCP_release_5.7.3,"
203		  "WinSCP_release_5.7.4",
204					SSH_OLD_DHGEX },
205		{ NULL,			0 }
206	};
207
208	/* process table, return first match */
209	for (i = 0; check[i].pat; i++) {
210		if (match_pattern_list(version, check[i].pat, 0) == 1) {
211			debug("match: %s pat %s compat 0x%08x",
212			    version, check[i].pat, check[i].bugs);
213			datafellows = check[i].bugs;	/* XXX for now */
214			return check[i].bugs;
215		}
216	}
217	debug("no match: %s", version);
218	return 0;
219}
220
221#define	SEP	","
222int
223proto_spec(const char *spec)
224{
225	char *s, *p, *q;
226	int ret = SSH_PROTO_UNKNOWN;
227
228	if (spec == NULL)
229		return ret;
230	q = s = strdup(spec);
231	if (s == NULL)
232		return ret;
233	for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
234		switch (atoi(p)) {
235		case 1:
236#ifdef WITH_SSH1
237			if (ret == SSH_PROTO_UNKNOWN)
238				ret |= SSH_PROTO_1_PREFERRED;
239			ret |= SSH_PROTO_1;
240#endif
241			break;
242		case 2:
243			ret |= SSH_PROTO_2;
244			break;
245		default:
246			logit("ignoring bad proto spec: '%s'.", p);
247			break;
248		}
249	}
250	free(s);
251	return ret;
252}
253
254char *
255compat_cipher_proposal(char *cipher_prop)
256{
257	if (!(datafellows & SSH_BUG_BIGENDIANAES))
258		return cipher_prop;
259	debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
260	if ((cipher_prop = match_filter_list(cipher_prop, "aes*")) == NULL)
261		fatal("match_filter_list failed");
262	debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
263	if (*cipher_prop == '\0')
264		fatal("No supported ciphers found");
265	return cipher_prop;
266}
267
268char *
269compat_pkalg_proposal(char *pkalg_prop)
270{
271	if (!(datafellows & SSH_BUG_RSASIGMD5))
272		return pkalg_prop;
273	debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
274	if ((pkalg_prop = match_filter_list(pkalg_prop, "ssh-rsa")) == NULL)
275		fatal("match_filter_list failed");
276	debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
277	if (*pkalg_prop == '\0')
278		fatal("No supported PK algorithms found");
279	return pkalg_prop;
280}
281
282char *
283compat_kex_proposal(char *p)
284{
285	if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
286		return p;
287	debug2("%s: original KEX proposal: %s", __func__, p);
288	if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
289		if ((p = match_filter_list(p,
290		    "curve25519-sha256@libssh.org")) == NULL)
291			fatal("match_filter_list failed");
292	if ((datafellows & SSH_OLD_DHGEX) != 0) {
293		if ((p = match_filter_list(p,
294		    "diffie-hellman-group-exchange-sha256,"
295		    "diffie-hellman-group-exchange-sha1")) == NULL)
296			fatal("match_filter_list failed");
297	}
298	debug2("%s: compat KEX proposal: %s", __func__, p);
299	if (*p == '\0')
300		fatal("No supported key exchange algorithms found");
301	return p;
302}
303
304