1/* $OpenBSD: compat.c,v 1.113 2018/08/13 02:41:05 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 "packet.h"
36#include "compat.h"
37#include "log.h"
38#include "match.h"
39#include "kex.h"
40
41int datafellows = 0;
42
43/* datafellows bug compatibility */
44u_int
45compat_datafellows(const char *version)
46{
47	int i;
48	static struct {
49		char	*pat;
50		int	bugs;
51	} check[] = {
52		{ "OpenSSH_2.*,"
53		  "OpenSSH_3.0*,"
54		  "OpenSSH_3.1*",	SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
55					SSH_BUG_SIGTYPE},
56		{ "OpenSSH_3.*",	SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
57		{ "Sun_SSH_1.0*",	SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
58					SSH_BUG_SIGTYPE},
59		{ "OpenSSH_2*,"
60		  "OpenSSH_3*,"
61		  "OpenSSH_4*",		SSH_BUG_SIGTYPE },
62		{ "OpenSSH_5*",		SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
63					SSH_BUG_SIGTYPE},
64		{ "OpenSSH_6.6.1*",	SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
65		{ "OpenSSH_6.5*,"
66		  "OpenSSH_6.6*",	SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
67					SSH_BUG_SIGTYPE},
68		{ "OpenSSH_7.0*,"
69		  "OpenSSH_7.1*,"
70		  "OpenSSH_7.2*,"
71		  "OpenSSH_7.3*,"
72		  "OpenSSH_7.4*,"
73		  "OpenSSH_7.5*,"
74		  "OpenSSH_7.6*,"
75		  "OpenSSH_7.7*",	SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
76		{ "OpenSSH*",		SSH_NEW_OPENSSH },
77		{ "*MindTerm*",		0 },
78		{ "3.0.*",		SSH_BUG_DEBUG },
79		{ "3.0 SecureCRT*",	SSH_OLD_SESSIONID },
80		{ "1.7 SecureFX*",	SSH_OLD_SESSIONID },
81		{ "1.2.18*,"
82		  "1.2.19*,"
83		  "1.2.20*,"
84		  "1.2.21*,"
85		  "1.2.22*",		SSH_BUG_IGNOREMSG },
86		{ "1.3.2*",		/* F-Secure */
87					SSH_BUG_IGNOREMSG },
88		{ "Cisco-1.*",		SSH_BUG_DHGEX_LARGE|
89					SSH_BUG_HOSTKEYS },
90		{ "*SSH Compatible Server*",			/* Netscreen */
91					SSH_BUG_PASSWORDPAD },
92		{ "*OSU_0*,"
93		  "OSU_1.0*,"
94		  "OSU_1.1*,"
95		  "OSU_1.2*,"
96		  "OSU_1.3*,"
97		  "OSU_1.4*,"
98		  "OSU_1.5alpha1*,"
99		  "OSU_1.5alpha2*,"
100		  "OSU_1.5alpha3*",	SSH_BUG_PASSWORDPAD },
101		{ "*SSH_Version_Mapper*",
102					SSH_BUG_SCANNER },
103		{ "PuTTY_Local:*,"	/* dev versions < Sep 2014 */
104		  "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
105		  "PuTTY_Release_0.5*,"	/* 0.58-0.59 */
106		  "PuTTY_Release_0.60*,"
107		  "PuTTY_Release_0.61*,"
108		  "PuTTY_Release_0.62*,"
109		  "PuTTY_Release_0.63*,"
110		  "PuTTY_Release_0.64*",
111					SSH_OLD_DHGEX },
112		{ "FuTTY*",		SSH_OLD_DHGEX }, /* Putty Fork */
113		{ "Probe-*",
114					SSH_BUG_PROBE },
115		{ "TeraTerm SSH*,"
116		  "TTSSH/1.5.*,"
117		  "TTSSH/2.1*,"
118		  "TTSSH/2.2*,"
119		  "TTSSH/2.3*,"
120		  "TTSSH/2.4*,"
121		  "TTSSH/2.5*,"
122		  "TTSSH/2.6*,"
123		  "TTSSH/2.70*,"
124		  "TTSSH/2.71*,"
125		  "TTSSH/2.72*",	SSH_BUG_HOSTKEYS },
126		{ "WinSCP_release_4*,"
127		  "WinSCP_release_5.0*,"
128		  "WinSCP_release_5.1,"
129		  "WinSCP_release_5.1.*,"
130		  "WinSCP_release_5.5,"
131		  "WinSCP_release_5.5.*,"
132		  "WinSCP_release_5.6,"
133		  "WinSCP_release_5.6.*,"
134		  "WinSCP_release_5.7,"
135		  "WinSCP_release_5.7.1,"
136		  "WinSCP_release_5.7.2,"
137		  "WinSCP_release_5.7.3,"
138		  "WinSCP_release_5.7.4",
139					SSH_OLD_DHGEX },
140		{ "ConfD-*",
141					SSH_BUG_UTF8TTYMODE },
142		{ "Twisted_*",		0 },
143		{ "Twisted*",		SSH_BUG_DEBUG },
144		{ NULL,			0 }
145	};
146
147	/* process table, return first match */
148	for (i = 0; check[i].pat; i++) {
149		if (match_pattern_list(version, check[i].pat, 0) == 1) {
150			debug("match: %s pat %s compat 0x%08x",
151			    version, check[i].pat, check[i].bugs);
152			datafellows = check[i].bugs;	/* XXX for now */
153			return check[i].bugs;
154		}
155	}
156	debug("no match: %s", version);
157	return 0;
158}
159
160#define	SEP	","
161int
162proto_spec(const char *spec)
163{
164	char *s, *p, *q;
165	int ret = SSH_PROTO_UNKNOWN;
166
167	if (spec == NULL)
168		return ret;
169	q = s = strdup(spec);
170	if (s == NULL)
171		return ret;
172	for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
173		switch (atoi(p)) {
174		case 2:
175			ret |= SSH_PROTO_2;
176			break;
177		default:
178			logit("ignoring bad proto spec: '%s'.", p);
179			break;
180		}
181	}
182	free(s);
183	return ret;
184}
185
186char *
187compat_cipher_proposal(char *cipher_prop)
188{
189	if (!(datafellows & SSH_BUG_BIGENDIANAES))
190		return cipher_prop;
191	debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
192	if ((cipher_prop = match_filter_blacklist(cipher_prop, "aes*")) == NULL)
193		fatal("match_filter_blacklist failed");
194	debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
195	if (*cipher_prop == '\0')
196		fatal("No supported ciphers found");
197	return cipher_prop;
198}
199
200char *
201compat_pkalg_proposal(char *pkalg_prop)
202{
203	if (!(datafellows & SSH_BUG_RSASIGMD5))
204		return pkalg_prop;
205	debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
206	if ((pkalg_prop = match_filter_blacklist(pkalg_prop, "ssh-rsa")) == NULL)
207		fatal("match_filter_blacklist failed");
208	debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
209	if (*pkalg_prop == '\0')
210		fatal("No supported PK algorithms found");
211	return pkalg_prop;
212}
213
214char *
215compat_kex_proposal(char *p)
216{
217	if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
218		return p;
219	debug2("%s: original KEX proposal: %s", __func__, p);
220	if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
221		if ((p = match_filter_blacklist(p,
222		    "curve25519-sha256@libssh.org")) == NULL)
223			fatal("match_filter_blacklist failed");
224	if ((datafellows & SSH_OLD_DHGEX) != 0) {
225		if ((p = match_filter_blacklist(p,
226		    "diffie-hellman-group-exchange-sha256,"
227		    "diffie-hellman-group-exchange-sha1")) == NULL)
228			fatal("match_filter_blacklist failed");
229	}
230	debug2("%s: compat KEX proposal: %s", __func__, p);
231	if (*p == '\0')
232		fatal("No supported key exchange algorithms found");
233	return p;
234}
235
236