1 /* $OpenBSD: compat.c,v 1.118 2021/06/06 03:40:39 djm 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 #include "kex.h" 40 41 /* determine bug flags from SSH protocol banner */ 42 void 43 compat_banner(struct ssh *ssh, const char *version) 44 { 45 int i; 46 static struct { 47 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_7.4*," 73 "OpenSSH_7.5*," 74 "OpenSSH_7.6*," 75 "OpenSSH_7.7*", SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE}, 76 { "OpenSSH*", SSH_NEW_OPENSSH }, 77 { "*MindTerm*", 0 }, 78 { "3.0.*", SSH_BUG_DEBUG }, 79 { "3.0 SecureCRT*", SSH_OLD_SESSIONID }, 80 { "1.7 SecureFX*", SSH_OLD_SESSIONID }, 81 { "1.2.18*," 82 "1.2.19*," 83 "1.2.20*," 84 "1.2.21*," 85 "1.2.22*", SSH_BUG_IGNOREMSG }, 86 { "1.3.2*", /* F-Secure */ 87 SSH_BUG_IGNOREMSG }, 88 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE| 89 SSH_BUG_HOSTKEYS }, 90 { "*SSH Compatible Server*", /* Netscreen */ 91 SSH_BUG_PASSWORDPAD }, 92 { "*OSU_0*," 93 "OSU_1.0*," 94 "OSU_1.1*," 95 "OSU_1.2*," 96 "OSU_1.3*," 97 "OSU_1.4*," 98 "OSU_1.5alpha1*," 99 "OSU_1.5alpha2*," 100 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 101 { "*SSH_Version_Mapper*", 102 SSH_BUG_SCANNER }, 103 { "PuTTY_Local:*," /* dev versions < Sep 2014 */ 104 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */ 105 "PuTTY_Release_0.5*," /* 0.58-0.59 */ 106 "PuTTY_Release_0.60*," 107 "PuTTY_Release_0.61*," 108 "PuTTY_Release_0.62*," 109 "PuTTY_Release_0.63*," 110 "PuTTY_Release_0.64*", 111 SSH_OLD_DHGEX }, 112 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */ 113 { "Probe-*", 114 SSH_BUG_PROBE }, 115 { "TeraTerm SSH*," 116 "TTSSH/1.5.*," 117 "TTSSH/2.1*," 118 "TTSSH/2.2*," 119 "TTSSH/2.3*," 120 "TTSSH/2.4*," 121 "TTSSH/2.5*," 122 "TTSSH/2.6*," 123 "TTSSH/2.70*," 124 "TTSSH/2.71*," 125 "TTSSH/2.72*", SSH_BUG_HOSTKEYS }, 126 { "WinSCP_release_4*," 127 "WinSCP_release_5.0*," 128 "WinSCP_release_5.1," 129 "WinSCP_release_5.1.*," 130 "WinSCP_release_5.5," 131 "WinSCP_release_5.5.*," 132 "WinSCP_release_5.6," 133 "WinSCP_release_5.6.*," 134 "WinSCP_release_5.7," 135 "WinSCP_release_5.7.1," 136 "WinSCP_release_5.7.2," 137 "WinSCP_release_5.7.3," 138 "WinSCP_release_5.7.4", 139 SSH_OLD_DHGEX }, 140 { "ConfD-*", 141 SSH_BUG_UTF8TTYMODE }, 142 { "Twisted_*", 0 }, 143 { "Twisted*", SSH_BUG_DEBUG }, 144 { NULL, 0 } 145 }; 146 147 /* process table, return first match */ 148 ssh->compat = 0; 149 for (i = 0; check[i].pat; i++) { 150 if (match_pattern_list(version, check[i].pat, 0) == 1) { 151 debug_f("match: %s pat %s compat 0x%08x", 152 version, check[i].pat, check[i].bugs); 153 ssh->compat = check[i].bugs; 154 return; 155 } 156 } 157 debug_f("no match: %s", version); 158 } 159 160 char * 161 compat_cipher_proposal(struct ssh *ssh, char *cipher_prop) 162 { 163 if (!(ssh->compat & SSH_BUG_BIGENDIANAES)) 164 return cipher_prop; 165 debug2_f("original cipher proposal: %s", cipher_prop); 166 if ((cipher_prop = match_filter_denylist(cipher_prop, "aes*")) == NULL) 167 fatal("match_filter_denylist failed"); 168 debug2_f("compat cipher proposal: %s", cipher_prop); 169 if (*cipher_prop == '\0') 170 fatal("No supported ciphers found"); 171 return cipher_prop; 172 } 173 174 char * 175 compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop) 176 { 177 if (!(ssh->compat & SSH_BUG_RSASIGMD5)) 178 return pkalg_prop; 179 debug2_f("original public key proposal: %s", pkalg_prop); 180 if ((pkalg_prop = match_filter_denylist(pkalg_prop, "ssh-rsa")) == NULL) 181 fatal("match_filter_denylist failed"); 182 debug2_f("compat public key proposal: %s", pkalg_prop); 183 if (*pkalg_prop == '\0') 184 fatal("No supported PK algorithms found"); 185 return pkalg_prop; 186 } 187 188 char * 189 compat_kex_proposal(struct ssh *ssh, char *p) 190 { 191 if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0) 192 return p; 193 debug2_f("original KEX proposal: %s", p); 194 if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0) 195 if ((p = match_filter_denylist(p, 196 "curve25519-sha256@libssh.org")) == NULL) 197 fatal("match_filter_denylist failed"); 198 if ((ssh->compat & SSH_OLD_DHGEX) != 0) { 199 if ((p = match_filter_denylist(p, 200 "diffie-hellman-group-exchange-sha256," 201 "diffie-hellman-group-exchange-sha1")) == NULL) 202 fatal("match_filter_denylist failed"); 203 } 204 debug2_f("compat KEX proposal: %s", p); 205 if (*p == '\0') 206 fatal("No supported key exchange algorithms found"); 207 return p; 208 } 209 210