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 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 * 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