1 /* $NetBSD: compat.c,v 1.26 2023/07/26 17:58:15 christos Exp $ */
2 /* $OpenBSD: compat.c,v 1.126 2023/03/06 12:14:48 dtucker Exp $ */
3 /*
4 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include "includes.h"
28 __RCSID("$NetBSD: compat.c,v 1.26 2023/07/26 17:58:15 christos Exp $");
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 "packet.h"
37 #include "compat.h"
38 #include "log.h"
39 #include "match.h"
40
41 /* determine bug flags from SSH protocol banner */
42 void
compat_banner(struct ssh * ssh,const char * version)43 compat_banner(struct ssh *ssh, const char *version)
44 {
45 int i;
46 static struct {
47 const char *pat;
48 int bugs;
49 } check[] = {
50 { "OpenSSH_2.*,"
51 "OpenSSH_3.0*,"
52 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
53 SSH_BUG_SIGTYPE},
54 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
55 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
56 SSH_BUG_SIGTYPE},
57 { "OpenSSH_2*,"
58 "OpenSSH_3*,"
59 "OpenSSH_4*", SSH_BUG_SIGTYPE },
60 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
61 SSH_BUG_SIGTYPE},
62 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
63 { "OpenSSH_6.5*,"
64 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
65 SSH_BUG_SIGTYPE},
66 { "OpenSSH_7.4*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
67 SSH_BUG_SIGTYPE74},
68 { "OpenSSH_7.0*,"
69 "OpenSSH_7.1*,"
70 "OpenSSH_7.2*,"
71 "OpenSSH_7.3*,"
72 "OpenSSH_7.5*,"
73 "OpenSSH_7.6*,"
74 "OpenSSH_7.7*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
75 { "OpenSSH*", SSH_NEW_OPENSSH },
76 { "*MindTerm*", 0 },
77 { "3.0.*", SSH_BUG_DEBUG },
78 { "3.0 SecureCRT*", SSH_OLD_SESSIONID },
79 { "1.7 SecureFX*", SSH_OLD_SESSIONID },
80 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE|
81 SSH_BUG_HOSTKEYS },
82 { "*SSH_Version_Mapper*",
83 SSH_BUG_SCANNER },
84 { "PuTTY_Local:*," /* dev versions < Sep 2014 */
85 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
86 "PuTTY_Release_0.5*," /* 0.58-0.59 */
87 "PuTTY_Release_0.60*,"
88 "PuTTY_Release_0.61*,"
89 "PuTTY_Release_0.62*,"
90 "PuTTY_Release_0.63*,"
91 "PuTTY_Release_0.64*",
92 SSH_OLD_DHGEX },
93 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */
94 { "Probe-*",
95 SSH_BUG_PROBE },
96 { "TeraTerm SSH*,"
97 "TTSSH/1.5.*,"
98 "TTSSH/2.1*,"
99 "TTSSH/2.2*,"
100 "TTSSH/2.3*,"
101 "TTSSH/2.4*,"
102 "TTSSH/2.5*,"
103 "TTSSH/2.6*,"
104 "TTSSH/2.70*,"
105 "TTSSH/2.71*,"
106 "TTSSH/2.72*", SSH_BUG_HOSTKEYS },
107 { "WinSCP_release_4*,"
108 "WinSCP_release_5.0*,"
109 "WinSCP_release_5.1,"
110 "WinSCP_release_5.1.*,"
111 "WinSCP_release_5.5,"
112 "WinSCP_release_5.5.*,"
113 "WinSCP_release_5.6,"
114 "WinSCP_release_5.6.*,"
115 "WinSCP_release_5.7,"
116 "WinSCP_release_5.7.1,"
117 "WinSCP_release_5.7.2,"
118 "WinSCP_release_5.7.3,"
119 "WinSCP_release_5.7.4",
120 SSH_OLD_DHGEX },
121 { "ConfD-*",
122 SSH_BUG_UTF8TTYMODE },
123 { "Twisted_*", 0 },
124 { "Twisted*", SSH_BUG_DEBUG },
125 { NULL, 0 }
126 };
127
128 /* process table, return first match */
129 ssh->compat = 0;
130 for (i = 0; check[i].pat; i++) {
131 if (match_pattern_list(version, check[i].pat, 0) == 1) {
132 debug_f("match: %s pat %s compat 0x%08x",
133 version, check[i].pat, check[i].bugs);
134 ssh->compat = check[i].bugs;
135 return;
136 }
137 }
138 debug_f("no match: %s", version);
139 }
140
141 /* Always returns pointer to allocated memory, caller must free. */
142 char *
compat_kex_proposal(struct ssh * ssh,const char * p)143 compat_kex_proposal(struct ssh *ssh, const char *p)
144 {
145 char *cp = NULL, *cp2 = NULL;
146
147 if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
148 return xstrdup(p);
149 debug2_f("original KEX proposal: %s", p);
150 if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
151 if ((cp = match_filter_denylist(p,
152 "curve25519-sha256@libssh.org")) == NULL)
153 fatal("match_filter_denylist failed");
154 if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
155 if ((cp2 = match_filter_denylist(cp ? cp : p,
156 "diffie-hellman-group-exchange-sha256,"
157 "diffie-hellman-group-exchange-sha1")) == NULL)
158 fatal("match_filter_denylist failed");
159 free(cp);
160 cp = cp2;
161 }
162 if (cp == NULL || *cp == '\0')
163 fatal("No supported key exchange algorithms found");
164 debug2_f("compat KEX proposal: %s", cp);
165 return cp;
166 }
167
168