1 /* $OpenBSD: compat.c,v 1.126 2023/03/06 12:14:48 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 "packet.h"
36 #include "compat.h"
37 #include "log.h"
38 #include "match.h"
39
40 /* determine bug flags from SSH protocol banner */
41 void
compat_banner(struct ssh * ssh,const char * version)42 compat_banner(struct ssh *ssh, const char *version)
43 {
44 int i;
45 static struct {
46 char *pat;
47 int bugs;
48 } check[] = {
49 { "OpenSSH_2.*,"
50 "OpenSSH_3.0*,"
51 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
52 SSH_BUG_SIGTYPE},
53 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
54 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
55 SSH_BUG_SIGTYPE},
56 { "OpenSSH_2*,"
57 "OpenSSH_3*,"
58 "OpenSSH_4*", SSH_BUG_SIGTYPE },
59 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
60 SSH_BUG_SIGTYPE},
61 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
62 { "OpenSSH_6.5*,"
63 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
64 SSH_BUG_SIGTYPE},
65 { "OpenSSH_7.4*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
66 SSH_BUG_SIGTYPE74},
67 { "OpenSSH_7.0*,"
68 "OpenSSH_7.1*,"
69 "OpenSSH_7.2*,"
70 "OpenSSH_7.3*,"
71 "OpenSSH_7.5*,"
72 "OpenSSH_7.6*,"
73 "OpenSSH_7.7*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
74 { "OpenSSH*", SSH_NEW_OPENSSH },
75 { "*MindTerm*", 0 },
76 { "3.0.*", SSH_BUG_DEBUG },
77 { "3.0 SecureCRT*", SSH_OLD_SESSIONID },
78 { "1.7 SecureFX*", SSH_OLD_SESSIONID },
79 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE|
80 SSH_BUG_HOSTKEYS },
81 { "*SSH_Version_Mapper*",
82 SSH_BUG_SCANNER },
83 { "PuTTY_Local:*," /* dev versions < Sep 2014 */
84 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
85 "PuTTY_Release_0.5*," /* 0.58-0.59 */
86 "PuTTY_Release_0.60*,"
87 "PuTTY_Release_0.61*,"
88 "PuTTY_Release_0.62*,"
89 "PuTTY_Release_0.63*,"
90 "PuTTY_Release_0.64*",
91 SSH_OLD_DHGEX },
92 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */
93 { "Probe-*",
94 SSH_BUG_PROBE },
95 { "TeraTerm SSH*,"
96 "TTSSH/1.5.*,"
97 "TTSSH/2.1*,"
98 "TTSSH/2.2*,"
99 "TTSSH/2.3*,"
100 "TTSSH/2.4*,"
101 "TTSSH/2.5*,"
102 "TTSSH/2.6*,"
103 "TTSSH/2.70*,"
104 "TTSSH/2.71*,"
105 "TTSSH/2.72*", SSH_BUG_HOSTKEYS },
106 { "WinSCP_release_4*,"
107 "WinSCP_release_5.0*,"
108 "WinSCP_release_5.1,"
109 "WinSCP_release_5.1.*,"
110 "WinSCP_release_5.5,"
111 "WinSCP_release_5.5.*,"
112 "WinSCP_release_5.6,"
113 "WinSCP_release_5.6.*,"
114 "WinSCP_release_5.7,"
115 "WinSCP_release_5.7.1,"
116 "WinSCP_release_5.7.2,"
117 "WinSCP_release_5.7.3,"
118 "WinSCP_release_5.7.4",
119 SSH_OLD_DHGEX },
120 { "ConfD-*",
121 SSH_BUG_UTF8TTYMODE },
122 { "Twisted_*", 0 },
123 { "Twisted*", SSH_BUG_DEBUG },
124 { NULL, 0 }
125 };
126
127 /* process table, return first match */
128 ssh->compat = 0;
129 for (i = 0; check[i].pat; i++) {
130 if (match_pattern_list(version, check[i].pat, 0) == 1) {
131 debug_f("match: %s pat %s compat 0x%08x",
132 version, check[i].pat, check[i].bugs);
133 ssh->compat = check[i].bugs;
134 return;
135 }
136 }
137 debug_f("no match: %s", version);
138 }
139
140 /* Always returns pointer to allocated memory, caller must free. */
141 char *
compat_kex_proposal(struct ssh * ssh,const char * p)142 compat_kex_proposal(struct ssh *ssh, const char *p)
143 {
144 char *cp = NULL, *cp2 = NULL;
145
146 if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
147 return xstrdup(p);
148 debug2_f("original KEX proposal: %s", p);
149 if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
150 if ((cp = match_filter_denylist(p,
151 "curve25519-sha256@libssh.org")) == NULL)
152 fatal("match_filter_denylist failed");
153 if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
154 if ((cp2 = match_filter_denylist(cp ? cp : p,
155 "diffie-hellman-group-exchange-sha256,"
156 "diffie-hellman-group-exchange-sha1")) == NULL)
157 fatal("match_filter_denylist failed");
158 free(cp);
159 cp = cp2;
160 }
161 if (cp == NULL || *cp == '\0')
162 fatal("No supported key exchange algorithms found");
163 debug2_f("compat KEX proposal: %s", cp);
164 return cp;
165 }
166
167