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 
41 int compat13 = 0;
42 int compat20 = 0;
43 int datafellows = 0;
44 
45 void
enable_compat20(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
enable_compat13(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
compat_datafellows(const char * version)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 		{ "*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	","
188 int
proto_spec(const char * spec)189 proto_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  */
222 static char *
filter_proposal(char * proposal,const char * filter)223 filter_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 
247 char *
compat_cipher_proposal(char * cipher_prop)248 compat_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 
260 char *
compat_pkalg_proposal(char * pkalg_prop)261 compat_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 
273 char *
compat_kex_proposal(char * kex_prop)274 compat_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