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