1 /* $OpenBSD: compat.c,v 1.100 2017/02/03 23:01:19 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 "buffer.h"
36 #include "packet.h"
37 #include "compat.h"
38 #include "log.h"
39 #include "match.h"
40 #include "kex.h"
41
42 int compat13 = 0;
43 int compat20 = 0;
44 int datafellows = 0;
45
46 void
enable_compat20(void)47 enable_compat20(void)
48 {
49 if (compat20)
50 return;
51 debug("Enabling compatibility mode for protocol 2.0");
52 compat20 = 1;
53 }
54 void
enable_compat13(void)55 enable_compat13(void)
56 {
57 debug("Enabling compatibility mode for protocol 1.3");
58 compat13 = 1;
59 }
60 /* datafellows bug compatibility */
61 u_int
compat_datafellows(const char * version)62 compat_datafellows(const char *version)
63 {
64 int i;
65 static struct {
66 char *pat;
67 int bugs;
68 } check[] = {
69 { "OpenSSH-2.0*,"
70 "OpenSSH-2.1*,"
71 "OpenSSH_2.1*,"
72 "OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER|
73 SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
74 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
75 { "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES|
76 SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
77 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
78 { "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
79 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
80 SSH_OLD_FORWARD_ADDR},
81 { "OpenSSH_2.5.0p1*,"
82 "OpenSSH_2.5.1p1*",
83 SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
84 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
85 SSH_OLD_FORWARD_ADDR},
86 { "OpenSSH_2.5.0*,"
87 "OpenSSH_2.5.1*,"
88 "OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
89 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
90 { "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
91 SSH_OLD_FORWARD_ADDR},
92 { "OpenSSH_2.*,"
93 "OpenSSH_3.0*,"
94 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
95 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR },
96 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
97 { "OpenSSH_4*", 0 },
98 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
99 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH},
100 { "OpenSSH_6.5*,"
101 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
102 { "OpenSSH*", SSH_NEW_OPENSSH },
103 { "*MindTerm*", 0 },
104 { "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
105 SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
106 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
107 SSH_BUG_FIRSTKEX },
108 { "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
109 SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
110 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
111 SSH_BUG_FIRSTKEX },
112 { "2.0.13*,"
113 "2.0.14*,"
114 "2.0.15*,"
115 "2.0.16*,"
116 "2.0.17*,"
117 "2.0.18*,"
118 "2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
119 SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
120 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
121 SSH_BUG_PKOK|SSH_BUG_RSASIGMD5|
122 SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE|
123 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
124 { "2.0.11*,"
125 "2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
126 SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
127 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
128 SSH_BUG_PKAUTH|SSH_BUG_PKOK|
129 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
130 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
131 { "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
132 SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
133 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
134 SSH_BUG_PKAUTH|SSH_BUG_PKOK|
135 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
136 SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN|
137 SSH_BUG_FIRSTKEX },
138 { "2.2.0*,"
139 "2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG|
140 SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX },
141 { "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5|
142 SSH_BUG_FIRSTKEX },
143 { "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */
144 { "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX|
145 SSH_BUG_RFWD_ADDR },
146 { "3.0.*", SSH_BUG_DEBUG },
147 { "3.0 SecureCRT*", SSH_OLD_SESSIONID },
148 { "1.7 SecureFX*", SSH_OLD_SESSIONID },
149 { "1.2.18*,"
150 "1.2.19*,"
151 "1.2.20*,"
152 "1.2.21*,"
153 "1.2.22*", SSH_BUG_IGNOREMSG },
154 { "1.3.2*", /* F-Secure */
155 SSH_BUG_IGNOREMSG },
156 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE|
157 SSH_BUG_HOSTKEYS },
158 { "*SSH Compatible Server*", /* Netscreen */
159 SSH_BUG_PASSWORDPAD },
160 { "*OSU_0*,"
161 "OSU_1.0*,"
162 "OSU_1.1*,"
163 "OSU_1.2*,"
164 "OSU_1.3*,"
165 "OSU_1.4*,"
166 "OSU_1.5alpha1*,"
167 "OSU_1.5alpha2*,"
168 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD },
169 { "*SSH_Version_Mapper*",
170 SSH_BUG_SCANNER },
171 { "PuTTY_Local:*," /* dev versions < Sep 2014 */
172 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
173 "PuTTY_Release_0.5*," /* 0.58-0.59 */
174 "PuTTY_Release_0.60*,"
175 "PuTTY_Release_0.61*,"
176 "PuTTY_Release_0.62*,"
177 "PuTTY_Release_0.63*,"
178 "PuTTY_Release_0.64*",
179 SSH_OLD_DHGEX },
180 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */
181 { "Probe-*",
182 SSH_BUG_PROBE },
183 { "TeraTerm SSH*,"
184 "TTSSH/1.5.*,"
185 "TTSSH/2.1*,"
186 "TTSSH/2.2*,"
187 "TTSSH/2.3*,"
188 "TTSSH/2.4*,"
189 "TTSSH/2.5*,"
190 "TTSSH/2.6*,"
191 "TTSSH/2.70*,"
192 "TTSSH/2.71*,"
193 "TTSSH/2.72*", SSH_BUG_HOSTKEYS },
194 { "WinSCP_release_4*,"
195 "WinSCP_release_5.0*,"
196 "WinSCP_release_5.1*,"
197 "WinSCP_release_5.5*,"
198 "WinSCP_release_5.6*,"
199 "WinSCP_release_5.7,"
200 "WinSCP_release_5.7.1,"
201 "WinSCP_release_5.7.2,"
202 "WinSCP_release_5.7.3,"
203 "WinSCP_release_5.7.4",
204 SSH_OLD_DHGEX },
205 { NULL, 0 }
206 };
207
208 /* process table, return first match */
209 for (i = 0; check[i].pat; i++) {
210 if (match_pattern_list(version, check[i].pat, 0) == 1) {
211 debug("match: %s pat %s compat 0x%08x",
212 version, check[i].pat, check[i].bugs);
213 datafellows = check[i].bugs; /* XXX for now */
214 return check[i].bugs;
215 }
216 }
217 debug("no match: %s", version);
218 return 0;
219 }
220
221 #define SEP ","
222 int
proto_spec(const char * spec)223 proto_spec(const char *spec)
224 {
225 char *s, *p, *q;
226 int ret = SSH_PROTO_UNKNOWN;
227
228 if (spec == NULL)
229 return ret;
230 q = s = strdup(spec);
231 if (s == NULL)
232 return ret;
233 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
234 switch (atoi(p)) {
235 case 1:
236 #ifdef WITH_SSH1
237 if (ret == SSH_PROTO_UNKNOWN)
238 ret |= SSH_PROTO_1_PREFERRED;
239 ret |= SSH_PROTO_1;
240 #endif
241 break;
242 case 2:
243 ret |= SSH_PROTO_2;
244 break;
245 default:
246 logit("ignoring bad proto spec: '%s'.", p);
247 break;
248 }
249 }
250 free(s);
251 return ret;
252 }
253
254 char *
compat_cipher_proposal(char * cipher_prop)255 compat_cipher_proposal(char *cipher_prop)
256 {
257 if (!(datafellows & SSH_BUG_BIGENDIANAES))
258 return cipher_prop;
259 debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
260 if ((cipher_prop = match_filter_list(cipher_prop, "aes*")) == NULL)
261 fatal("match_filter_list failed");
262 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
263 if (*cipher_prop == '\0')
264 fatal("No supported ciphers found");
265 return cipher_prop;
266 }
267
268 char *
compat_pkalg_proposal(char * pkalg_prop)269 compat_pkalg_proposal(char *pkalg_prop)
270 {
271 if (!(datafellows & SSH_BUG_RSASIGMD5))
272 return pkalg_prop;
273 debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
274 if ((pkalg_prop = match_filter_list(pkalg_prop, "ssh-rsa")) == NULL)
275 fatal("match_filter_list failed");
276 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
277 if (*pkalg_prop == '\0')
278 fatal("No supported PK algorithms found");
279 return pkalg_prop;
280 }
281
282 char *
compat_kex_proposal(char * p)283 compat_kex_proposal(char *p)
284 {
285 if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
286 return p;
287 debug2("%s: original KEX proposal: %s", __func__, p);
288 if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
289 if ((p = match_filter_list(p,
290 "curve25519-sha256@libssh.org")) == NULL)
291 fatal("match_filter_list failed");
292 if ((datafellows & SSH_OLD_DHGEX) != 0) {
293 if ((p = match_filter_list(p,
294 "diffie-hellman-group-exchange-sha256,"
295 "diffie-hellman-group-exchange-sha1")) == NULL)
296 fatal("match_filter_list failed");
297 }
298 debug2("%s: compat KEX proposal: %s", __func__, p);
299 if (*p == '\0')
300 fatal("No supported key exchange algorithms found");
301 return p;
302 }
303
304