1 /* $OpenBSD: compat.c,v 1.82 2013/12/30 23:52:27 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 __RCSID("$FreeBSD$");
28
29 #include <sys/types.h>
30
31 #include <stdlib.h>
32 #include <string.h>
33 #include <stdarg.h>
34
35 #include "xmalloc.h"
36 #include "buffer.h"
37 #include "packet.h"
38 #include "compat.h"
39 #include "log.h"
40 #include "match.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 void
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 { "*SSH Compatible Server*", /* Netscreen */
157 SSH_BUG_PASSWORDPAD },
158 { "*OSU_0*,"
159 "OSU_1.0*,"
160 "OSU_1.1*,"
161 "OSU_1.2*,"
162 "OSU_1.3*,"
163 "OSU_1.4*,"
164 "OSU_1.5alpha1*,"
165 "OSU_1.5alpha2*,"
166 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD },
167 { "*SSH_Version_Mapper*",
168 SSH_BUG_SCANNER },
169 { "Probe-*",
170 SSH_BUG_PROBE },
171 { NULL, 0 }
172 };
173
174 /* process table, return first match */
175 for (i = 0; check[i].pat; i++) {
176 if (match_pattern_list(version, check[i].pat,
177 strlen(check[i].pat), 0) == 1) {
178 datafellows = check[i].bugs;
179 debug("match: %s pat %s compat 0x%08x",
180 version, check[i].pat, datafellows);
181 /*
182 * Check to see if the remote side is OpenSSH and not
183 * HPN. It is utterly strange to check it from the
184 * version string and expose the option that way.
185 */
186 if (strstr(version,"OpenSSH") != NULL &&
187 strstr(version,"hpn") == NULL) {
188 datafellows |= SSH_BUG_LARGEWINDOW;
189 debug("Remote is not HPN-aware");
190 }
191 return;
192 }
193 }
194 debug("no match: %s", version);
195 }
196
197 #define SEP ","
198 int
proto_spec(const char * spec)199 proto_spec(const char *spec)
200 {
201 char *s, *p, *q;
202 int ret = SSH_PROTO_UNKNOWN;
203
204 if (spec == NULL)
205 return ret;
206 q = s = xstrdup(spec);
207 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
208 switch (atoi(p)) {
209 case 1:
210 if (ret == SSH_PROTO_UNKNOWN)
211 ret |= SSH_PROTO_1_PREFERRED;
212 ret |= SSH_PROTO_1;
213 break;
214 case 2:
215 ret |= SSH_PROTO_2;
216 break;
217 default:
218 logit("ignoring bad proto spec: '%s'.", p);
219 break;
220 }
221 }
222 free(s);
223 return ret;
224 }
225
226 /*
227 * Filters a proposal string, excluding any algorithm matching the 'filter'
228 * pattern list.
229 */
230 static char *
filter_proposal(char * proposal,const char * filter)231 filter_proposal(char *proposal, const char *filter)
232 {
233 Buffer b;
234 char *orig_prop, *fix_prop;
235 char *cp, *tmp;
236
237 buffer_init(&b);
238 tmp = orig_prop = xstrdup(proposal);
239 while ((cp = strsep(&tmp, ",")) != NULL) {
240 if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) {
241 if (buffer_len(&b) > 0)
242 buffer_append(&b, ",", 1);
243 buffer_append(&b, cp, strlen(cp));
244 } else
245 debug2("Compat: skipping algorithm \"%s\"", cp);
246 }
247 buffer_append(&b, "\0", 1);
248 fix_prop = xstrdup(buffer_ptr(&b));
249 buffer_free(&b);
250 free(orig_prop);
251
252 return fix_prop;
253 }
254
255 char *
compat_cipher_proposal(char * cipher_prop)256 compat_cipher_proposal(char *cipher_prop)
257 {
258 if (!(datafellows & SSH_BUG_BIGENDIANAES))
259 return cipher_prop;
260 debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
261 cipher_prop = filter_proposal(cipher_prop, "aes*");
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 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
275 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
276 if (*pkalg_prop == '\0')
277 fatal("No supported PK algorithms found");
278 return pkalg_prop;
279 }
280
281 char *
compat_kex_proposal(char * kex_prop)282 compat_kex_proposal(char *kex_prop)
283 {
284 if (!(datafellows & SSH_BUG_CURVE25519PAD))
285 return kex_prop;
286 debug2("%s: original KEX proposal: %s", __func__, kex_prop);
287 kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
288 debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
289 if (*kex_prop == '\0')
290 fatal("No supported key exchange algorithms found");
291 return kex_prop;
292 }
293
294