1/* $OpenBSD: compat.c,v 1.87 2015/01/19 20:20:20 markus 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
41int compat13 = 0;
42int compat20 = 0;
43int datafellows = 0;
44
45void
46enable_compat20(void)
47{
48	if (compat20)
49		return;
50	debug("Enabling compatibility mode for protocol 2.0");
51	compat20 = 1;
52}
53void
54enable_compat13(void)
55{
56	debug("Enabling compatibility mode for protocol 1.3");
57	compat13 = 1;
58}
59/* datafellows bug compatibility */
60u_int
61compat_datafellows(const char *version)
62{
63	int i;
64	static struct {
65		char	*pat;
66		int	bugs;
67	} check[] = {
68		{ "OpenSSH-2.0*,"
69		  "OpenSSH-2.1*,"
70		  "OpenSSH_2.1*,"
71		  "OpenSSH_2.2*",	SSH_OLD_SESSIONID|SSH_BUG_BANNER|
72					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
73					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
74		{ "OpenSSH_2.3.0*",	SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES|
75					SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
76					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
77		{ "OpenSSH_2.3.*",	SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
78					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
79					SSH_OLD_FORWARD_ADDR},
80		{ "OpenSSH_2.5.0p1*,"
81		  "OpenSSH_2.5.1p1*",
82					SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
83					SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
84					SSH_OLD_FORWARD_ADDR},
85		{ "OpenSSH_2.5.0*,"
86		  "OpenSSH_2.5.1*,"
87		  "OpenSSH_2.5.2*",	SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
88					SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
89		{ "OpenSSH_2.5.3*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
90					SSH_OLD_FORWARD_ADDR},
91		{ "OpenSSH_2.*,"
92		  "OpenSSH_3.0*,"
93		  "OpenSSH_3.1*",	SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
94		{ "OpenSSH_3.*",	SSH_OLD_FORWARD_ADDR },
95		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
96		{ "OpenSSH_4*",		0 },
97		{ "OpenSSH_5*",		SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
98		{ "OpenSSH_6.6.1*",	SSH_NEW_OPENSSH},
99		{ "OpenSSH_6.5*,"
100		  "OpenSSH_6.6*",	SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
101		{ "OpenSSH*",		SSH_NEW_OPENSSH },
102		{ "*MindTerm*",		0 },
103		{ "2.1.0*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
104					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
105					SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
106					SSH_BUG_FIRSTKEX },
107		{ "2.1 *",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
108					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
109					SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
110					SSH_BUG_FIRSTKEX },
111		{ "2.0.13*,"
112		  "2.0.14*,"
113		  "2.0.15*,"
114		  "2.0.16*,"
115		  "2.0.17*,"
116		  "2.0.18*,"
117		  "2.0.19*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
118					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
119					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
120					SSH_BUG_PKOK|SSH_BUG_RSASIGMD5|
121					SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE|
122					SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
123		{ "2.0.11*,"
124		  "2.0.12*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
125					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
126					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
127					SSH_BUG_PKAUTH|SSH_BUG_PKOK|
128					SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
129					SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
130		{ "2.0.*",		SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
131					SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
132					SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
133					SSH_BUG_PKAUTH|SSH_BUG_PKOK|
134					SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
135					SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN|
136					SSH_BUG_FIRSTKEX },
137		{ "2.2.0*,"
138		  "2.3.0*",		SSH_BUG_HMAC|SSH_BUG_DEBUG|
139					SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX },
140		{ "2.3.*",		SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5|
141					SSH_BUG_FIRSTKEX },
142		{ "2.4",		SSH_OLD_SESSIONID },	/* Van Dyke */
143		{ "2.*",		SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX|
144					SSH_BUG_RFWD_ADDR },
145		{ "3.0.*",		SSH_BUG_DEBUG },
146		{ "3.0 SecureCRT*",	SSH_OLD_SESSIONID },
147		{ "1.7 SecureFX*",	SSH_OLD_SESSIONID },
148		{ "1.2.18*,"
149		  "1.2.19*,"
150		  "1.2.20*,"
151		  "1.2.21*,"
152		  "1.2.22*",		SSH_BUG_IGNOREMSG },
153		{ "1.3.2*",		/* F-Secure */
154					SSH_BUG_IGNOREMSG },
155		{ "*SSH Compatible Server*",			/* Netscreen */
156					SSH_BUG_PASSWORDPAD },
157		{ "*OSU_0*,"
158		  "OSU_1.0*,"
159		  "OSU_1.1*,"
160		  "OSU_1.2*,"
161		  "OSU_1.3*,"
162		  "OSU_1.4*,"
163		  "OSU_1.5alpha1*,"
164		  "OSU_1.5alpha2*,"
165		  "OSU_1.5alpha3*",	SSH_BUG_PASSWORDPAD },
166		{ "*SSH_Version_Mapper*",
167					SSH_BUG_SCANNER },
168		{ "Probe-*",
169					SSH_BUG_PROBE },
170		{ NULL,			0 }
171	};
172
173	/* process table, return first match */
174	for (i = 0; check[i].pat; i++) {
175		if (match_pattern_list(version, check[i].pat,
176		    strlen(check[i].pat), 0) == 1) {
177			debug("match: %s pat %s compat 0x%08x",
178			    version, check[i].pat, check[i].bugs);
179			datafellows = check[i].bugs;	/* XXX for now */
180			return check[i].bugs;
181		}
182	}
183	debug("no match: %s", version);
184	return 0;
185}
186
187#define	SEP	","
188int
189proto_spec(const char *spec)
190{
191	char *s, *p, *q;
192	int ret = SSH_PROTO_UNKNOWN;
193
194	if (spec == NULL)
195		return ret;
196	q = s = strdup(spec);
197	if (s == NULL)
198		return ret;
199	for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
200		switch (atoi(p)) {
201		case 1:
202			if (ret == SSH_PROTO_UNKNOWN)
203				ret |= SSH_PROTO_1_PREFERRED;
204			ret |= SSH_PROTO_1;
205			break;
206		case 2:
207			ret |= SSH_PROTO_2;
208			break;
209		default:
210			logit("ignoring bad proto spec: '%s'.", p);
211			break;
212		}
213	}
214	free(s);
215	return ret;
216}
217
218/*
219 * Filters a proposal string, excluding any algorithm matching the 'filter'
220 * pattern list.
221 */
222static char *
223filter_proposal(char *proposal, const char *filter)
224{
225	Buffer b;
226	char *orig_prop, *fix_prop;
227	char *cp, *tmp;
228
229	buffer_init(&b);
230	tmp = orig_prop = xstrdup(proposal);
231	while ((cp = strsep(&tmp, ",")) != NULL) {
232		if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) {
233			if (buffer_len(&b) > 0)
234				buffer_append(&b, ",", 1);
235			buffer_append(&b, cp, strlen(cp));
236		} else
237			debug2("Compat: skipping algorithm \"%s\"", cp);
238	}
239	buffer_append(&b, "\0", 1);
240	fix_prop = xstrdup((char *)buffer_ptr(&b));
241	buffer_free(&b);
242	free(orig_prop);
243
244	return fix_prop;
245}
246
247char *
248compat_cipher_proposal(char *cipher_prop)
249{
250	if (!(datafellows & SSH_BUG_BIGENDIANAES))
251		return cipher_prop;
252	debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
253	cipher_prop = filter_proposal(cipher_prop, "aes*");
254	debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
255	if (*cipher_prop == '\0')
256		fatal("No supported ciphers found");
257	return cipher_prop;
258}
259
260char *
261compat_pkalg_proposal(char *pkalg_prop)
262{
263	if (!(datafellows & SSH_BUG_RSASIGMD5))
264		return pkalg_prop;
265	debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
266	pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
267	debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
268	if (*pkalg_prop == '\0')
269		fatal("No supported PK algorithms found");
270	return pkalg_prop;
271}
272
273char *
274compat_kex_proposal(char *kex_prop)
275{
276	if (!(datafellows & SSH_BUG_CURVE25519PAD))
277		return kex_prop;
278	debug2("%s: original KEX proposal: %s", __func__, kex_prop);
279	kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
280	debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
281	if (*kex_prop == '\0')
282		fatal("No supported key exchange algorithms found");
283	return kex_prop;
284}
285
286