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 */ 42void 43compat_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. */ 142char * 143compat_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