xref: /openssh-portable/compat.c (revision c3903c38)
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 
41 int datafellows = 0;
42 
43 /* datafellows bug compatibility */
44 u_int
compat_datafellows(const char * version)45 compat_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	","
161 int
proto_spec(const char * spec)162 proto_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 
186 char *
compat_cipher_proposal(char * cipher_prop)187 compat_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 
200 char *
compat_pkalg_proposal(char * pkalg_prop)201 compat_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 
214 char *
compat_kex_proposal(char * p)215 compat_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