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 <sys/types.h>
27
28 #include <stdlib.h>
29 #include <string.h>
30 #include <stdarg.h>
31
32 #include "xmalloc.h"
33 #include "packet.h"
34 #include "compat.h"
35 #include "log.h"
36 #include "match.h"
37
38 /* determine bug flags from SSH protocol banner */
39 void
compat_banner(struct ssh * ssh,const char * version)40 compat_banner(struct ssh *ssh, const char *version)
41 {
42 int i;
43 static struct {
44 char *pat;
45 int bugs;
46 } check[] = {
47 { "OpenSSH_2.*,"
48 "OpenSSH_3.0*,"
49 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
50 SSH_BUG_SIGTYPE},
51 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
52 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
53 SSH_BUG_SIGTYPE},
54 { "OpenSSH_2*,"
55 "OpenSSH_3*,"
56 "OpenSSH_4*", SSH_BUG_SIGTYPE },
57 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
58 SSH_BUG_SIGTYPE},
59 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
60 { "OpenSSH_6.5*,"
61 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
62 SSH_BUG_SIGTYPE},
63 { "OpenSSH_7.4*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
64 SSH_BUG_SIGTYPE74},
65 { "OpenSSH_7.0*,"
66 "OpenSSH_7.1*,"
67 "OpenSSH_7.2*,"
68 "OpenSSH_7.3*,"
69 "OpenSSH_7.5*,"
70 "OpenSSH_7.6*,"
71 "OpenSSH_7.7*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
72 { "OpenSSH*", SSH_NEW_OPENSSH },
73 { "*MindTerm*", 0 },
74 { "3.0.*", SSH_BUG_DEBUG },
75 { "3.0 SecureCRT*", SSH_OLD_SESSIONID },
76 { "1.7 SecureFX*", SSH_OLD_SESSIONID },
77 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE|
78 SSH_BUG_HOSTKEYS },
79 { "*SSH_Version_Mapper*",
80 SSH_BUG_SCANNER },
81 { "PuTTY_Local:*," /* dev versions < Sep 2014 */
82 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
83 "PuTTY_Release_0.5*," /* 0.58-0.59 */
84 "PuTTY_Release_0.60*,"
85 "PuTTY_Release_0.61*,"
86 "PuTTY_Release_0.62*,"
87 "PuTTY_Release_0.63*,"
88 "PuTTY_Release_0.64*",
89 SSH_OLD_DHGEX },
90 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */
91 { "Probe-*",
92 SSH_BUG_PROBE },
93 { "TeraTerm SSH*,"
94 "TTSSH/1.5.*,"
95 "TTSSH/2.1*,"
96 "TTSSH/2.2*,"
97 "TTSSH/2.3*,"
98 "TTSSH/2.4*,"
99 "TTSSH/2.5*,"
100 "TTSSH/2.6*,"
101 "TTSSH/2.70*,"
102 "TTSSH/2.71*,"
103 "TTSSH/2.72*", SSH_BUG_HOSTKEYS },
104 { "WinSCP_release_4*,"
105 "WinSCP_release_5.0*,"
106 "WinSCP_release_5.1,"
107 "WinSCP_release_5.1.*,"
108 "WinSCP_release_5.5,"
109 "WinSCP_release_5.5.*,"
110 "WinSCP_release_5.6,"
111 "WinSCP_release_5.6.*,"
112 "WinSCP_release_5.7,"
113 "WinSCP_release_5.7.1,"
114 "WinSCP_release_5.7.2,"
115 "WinSCP_release_5.7.3,"
116 "WinSCP_release_5.7.4",
117 SSH_OLD_DHGEX },
118 { "ConfD-*",
119 SSH_BUG_UTF8TTYMODE },
120 { "Twisted_*", 0 },
121 { "Twisted*", SSH_BUG_DEBUG },
122 { NULL, 0 }
123 };
124
125 /* process table, return first match */
126 ssh->compat = 0;
127 for (i = 0; check[i].pat; i++) {
128 if (match_pattern_list(version, check[i].pat, 0) == 1) {
129 debug_f("match: %s pat %s compat 0x%08x",
130 version, check[i].pat, check[i].bugs);
131 ssh->compat = check[i].bugs;
132 return;
133 }
134 }
135 debug_f("no match: %s", version);
136 }
137
138 /* Always returns pointer to allocated memory, caller must free. */
139 char *
compat_kex_proposal(struct ssh * ssh,const char * p)140 compat_kex_proposal(struct ssh *ssh, const char *p)
141 {
142 char *cp = NULL, *cp2 = NULL;
143
144 if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
145 return xstrdup(p);
146 debug2_f("original KEX proposal: %s", p);
147 if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
148 if ((cp = match_filter_denylist(p,
149 "curve25519-sha256@libssh.org")) == NULL)
150 fatal("match_filter_denylist failed");
151 if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
152 if ((cp2 = match_filter_denylist(cp ? cp : p,
153 "diffie-hellman-group-exchange-sha256,"
154 "diffie-hellman-group-exchange-sha1")) == NULL)
155 fatal("match_filter_denylist failed");
156 free(cp);
157 cp = cp2;
158 }
159 if (cp == NULL || *cp == '\0')
160 fatal("No supported key exchange algorithms found");
161 debug2_f("compat KEX proposal: %s", cp);
162 return cp;
163 }
164
165