xref: /freebsd/crypto/openssh/compat.c (revision 076ad2f836d5f49dc1375f1677335a48fe0d4b82)
1 /* $OpenBSD: compat.c,v 1.99 2016/05/24 02:31:57 dtucker 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 
41 int compat13 = 0;
42 int compat20 = 0;
43 int datafellows = 0;
44 
45 void
46 enable_compat20(void)
47 {
48 	if (compat20)
49 		return;
50 	debug("Enabling compatibility mode for protocol 2.0");
51 	compat20 = 1;
52 }
53 void
54 enable_compat13(void)
55 {
56 	debug("Enabling compatibility mode for protocol 1.3");
57 	compat13 = 1;
58 }
59 /* datafellows bug compatibility */
60 u_int
61 compat_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 		{ "Cisco-1.*",		SSH_BUG_DHGEX_LARGE|
156 					SSH_BUG_HOSTKEYS },
157 		{ "*SSH Compatible Server*",			/* Netscreen */
158 					SSH_BUG_PASSWORDPAD },
159 		{ "*OSU_0*,"
160 		  "OSU_1.0*,"
161 		  "OSU_1.1*,"
162 		  "OSU_1.2*,"
163 		  "OSU_1.3*,"
164 		  "OSU_1.4*,"
165 		  "OSU_1.5alpha1*,"
166 		  "OSU_1.5alpha2*,"
167 		  "OSU_1.5alpha3*",	SSH_BUG_PASSWORDPAD },
168 		{ "*SSH_Version_Mapper*",
169 					SSH_BUG_SCANNER },
170 		{ "PuTTY_Local:*,"	/* dev versions < Sep 2014 */
171 		  "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
172 		  "PuTTY_Release_0.5*,"	/* 0.58-0.59 */
173 		  "PuTTY_Release_0.60*,"
174 		  "PuTTY_Release_0.61*,"
175 		  "PuTTY_Release_0.62*,"
176 		  "PuTTY_Release_0.63*,"
177 		  "PuTTY_Release_0.64*",
178 					SSH_OLD_DHGEX },
179 		{ "FuTTY*",		SSH_OLD_DHGEX }, /* Putty Fork */
180 		{ "Probe-*",
181 					SSH_BUG_PROBE },
182 		{ "TeraTerm SSH*,"
183 		  "TTSSH/1.5.*,"
184 		  "TTSSH/2.1*,"
185 		  "TTSSH/2.2*,"
186 		  "TTSSH/2.3*,"
187 		  "TTSSH/2.4*,"
188 		  "TTSSH/2.5*,"
189 		  "TTSSH/2.6*,"
190 		  "TTSSH/2.70*,"
191 		  "TTSSH/2.71*,"
192 		  "TTSSH/2.72*",	SSH_BUG_HOSTKEYS },
193 		{ "WinSCP_release_4*,"
194 		  "WinSCP_release_5.0*,"
195 		  "WinSCP_release_5.1*,"
196 		  "WinSCP_release_5.5*,"
197 		  "WinSCP_release_5.6*,"
198 		  "WinSCP_release_5.7,"
199 		  "WinSCP_release_5.7.1,"
200 		  "WinSCP_release_5.7.2,"
201 		  "WinSCP_release_5.7.3,"
202 		  "WinSCP_release_5.7.4",
203 					SSH_OLD_DHGEX },
204 		{ NULL,			0 }
205 	};
206 
207 	/* process table, return first match */
208 	for (i = 0; check[i].pat; i++) {
209 		if (match_pattern_list(version, check[i].pat, 0) == 1) {
210 			debug("match: %s pat %s compat 0x%08x",
211 			    version, check[i].pat, check[i].bugs);
212 			datafellows = check[i].bugs;	/* XXX for now */
213 			return check[i].bugs;
214 		}
215 	}
216 	debug("no match: %s", version);
217 	return 0;
218 }
219 
220 #define	SEP	","
221 int
222 proto_spec(const char *spec)
223 {
224 	char *s, *p, *q;
225 	int ret = SSH_PROTO_UNKNOWN;
226 
227 	if (spec == NULL)
228 		return ret;
229 	q = s = strdup(spec);
230 	if (s == NULL)
231 		return ret;
232 	for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
233 		switch (atoi(p)) {
234 		case 1:
235 #ifdef WITH_SSH1
236 			if (ret == SSH_PROTO_UNKNOWN)
237 				ret |= SSH_PROTO_1_PREFERRED;
238 			ret |= SSH_PROTO_1;
239 #endif
240 			break;
241 		case 2:
242 			ret |= SSH_PROTO_2;
243 			break;
244 		default:
245 			logit("ignoring bad proto spec: '%s'.", p);
246 			break;
247 		}
248 	}
249 	free(s);
250 	return ret;
251 }
252 
253 /*
254  * Filters a proposal string, excluding any algorithm matching the 'filter'
255  * pattern list.
256  */
257 static char *
258 filter_proposal(char *proposal, const char *filter)
259 {
260 	Buffer b;
261 	char *orig_prop, *fix_prop;
262 	char *cp, *tmp;
263 
264 	buffer_init(&b);
265 	tmp = orig_prop = xstrdup(proposal);
266 	while ((cp = strsep(&tmp, ",")) != NULL) {
267 		if (match_pattern_list(cp, filter, 0) != 1) {
268 			if (buffer_len(&b) > 0)
269 				buffer_append(&b, ",", 1);
270 			buffer_append(&b, cp, strlen(cp));
271 		} else
272 			debug2("Compat: skipping algorithm \"%s\"", cp);
273 	}
274 	buffer_append(&b, "\0", 1);
275 	fix_prop = xstrdup((char *)buffer_ptr(&b));
276 	buffer_free(&b);
277 	free(orig_prop);
278 
279 	return fix_prop;
280 }
281 
282 char *
283 compat_cipher_proposal(char *cipher_prop)
284 {
285 	if (!(datafellows & SSH_BUG_BIGENDIANAES))
286 		return cipher_prop;
287 	debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
288 	cipher_prop = filter_proposal(cipher_prop, "aes*");
289 	debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
290 	if (*cipher_prop == '\0')
291 		fatal("No supported ciphers found");
292 	return cipher_prop;
293 }
294 
295 char *
296 compat_pkalg_proposal(char *pkalg_prop)
297 {
298 	if (!(datafellows & SSH_BUG_RSASIGMD5))
299 		return pkalg_prop;
300 	debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
301 	pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
302 	debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
303 	if (*pkalg_prop == '\0')
304 		fatal("No supported PK algorithms found");
305 	return pkalg_prop;
306 }
307 
308 char *
309 compat_kex_proposal(char *p)
310 {
311 	if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
312 		return p;
313 	debug2("%s: original KEX proposal: %s", __func__, p);
314 	if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
315 		p = filter_proposal(p, "curve25519-sha256@libssh.org");
316 	if ((datafellows & SSH_OLD_DHGEX) != 0) {
317 		p = filter_proposal(p, "diffie-hellman-group-exchange-sha256");
318 		p = filter_proposal(p, "diffie-hellman-group-exchange-sha1");
319 	}
320 	debug2("%s: compat KEX proposal: %s", __func__, p);
321 	if (*p == '\0')
322 		fatal("No supported key exchange algorithms found");
323 	return p;
324 }
325 
326