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 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 * 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