1 /* $OpenBSD: compat.c,v 1.115 2020/07/05 23:59:45 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 <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 #include "kex.h" 38 39 int datafellows = 0; 40 41 /* datafellows bug compatibility */ 42 u_int 43 compat_datafellows(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_7.0*," 67 "OpenSSH_7.1*," 68 "OpenSSH_7.2*," 69 "OpenSSH_7.3*," 70 "OpenSSH_7.4*," 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 { "1.2.18*," 80 "1.2.19*," 81 "1.2.20*," 82 "1.2.21*," 83 "1.2.22*", SSH_BUG_IGNOREMSG }, 84 { "1.3.2*", /* F-Secure */ 85 SSH_BUG_IGNOREMSG }, 86 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE| 87 SSH_BUG_HOSTKEYS }, 88 { "*SSH Compatible Server*", /* Netscreen */ 89 SSH_BUG_PASSWORDPAD }, 90 { "*OSU_0*," 91 "OSU_1.0*," 92 "OSU_1.1*," 93 "OSU_1.2*," 94 "OSU_1.3*," 95 "OSU_1.4*," 96 "OSU_1.5alpha1*," 97 "OSU_1.5alpha2*," 98 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 99 { "*SSH_Version_Mapper*", 100 SSH_BUG_SCANNER }, 101 { "PuTTY_Local:*," /* dev versions < Sep 2014 */ 102 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */ 103 "PuTTY_Release_0.5*," /* 0.58-0.59 */ 104 "PuTTY_Release_0.60*," 105 "PuTTY_Release_0.61*," 106 "PuTTY_Release_0.62*," 107 "PuTTY_Release_0.63*," 108 "PuTTY_Release_0.64*", 109 SSH_OLD_DHGEX }, 110 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */ 111 { "Probe-*", 112 SSH_BUG_PROBE }, 113 { "TeraTerm SSH*," 114 "TTSSH/1.5.*," 115 "TTSSH/2.1*," 116 "TTSSH/2.2*," 117 "TTSSH/2.3*," 118 "TTSSH/2.4*," 119 "TTSSH/2.5*," 120 "TTSSH/2.6*," 121 "TTSSH/2.70*," 122 "TTSSH/2.71*," 123 "TTSSH/2.72*", SSH_BUG_HOSTKEYS }, 124 { "WinSCP_release_4*," 125 "WinSCP_release_5.0*," 126 "WinSCP_release_5.1," 127 "WinSCP_release_5.1.*," 128 "WinSCP_release_5.5," 129 "WinSCP_release_5.5.*," 130 "WinSCP_release_5.6," 131 "WinSCP_release_5.6.*," 132 "WinSCP_release_5.7," 133 "WinSCP_release_5.7.1," 134 "WinSCP_release_5.7.2," 135 "WinSCP_release_5.7.3," 136 "WinSCP_release_5.7.4", 137 SSH_OLD_DHGEX }, 138 { "ConfD-*", 139 SSH_BUG_UTF8TTYMODE }, 140 { "Twisted_*", 0 }, 141 { "Twisted*", SSH_BUG_DEBUG }, 142 { NULL, 0 } 143 }; 144 145 /* process table, return first match */ 146 for (i = 0; check[i].pat; i++) { 147 if (match_pattern_list(version, check[i].pat, 0) == 1) { 148 debug("match: %s pat %s compat 0x%08x", 149 version, check[i].pat, check[i].bugs); 150 datafellows = check[i].bugs; /* XXX for now */ 151 return check[i].bugs; 152 } 153 } 154 debug("no match: %s", version); 155 return 0; 156 } 157 158 char * 159 compat_cipher_proposal(char *cipher_prop) 160 { 161 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 162 return cipher_prop; 163 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 164 if ((cipher_prop = match_filter_denylist(cipher_prop, "aes*")) == NULL) 165 fatal("match_filter_denylist failed"); 166 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 167 if (*cipher_prop == '\0') 168 fatal("No supported ciphers found"); 169 return cipher_prop; 170 } 171 172 char * 173 compat_pkalg_proposal(char *pkalg_prop) 174 { 175 if (!(datafellows & SSH_BUG_RSASIGMD5)) 176 return pkalg_prop; 177 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 178 if ((pkalg_prop = match_filter_denylist(pkalg_prop, "ssh-rsa")) == NULL) 179 fatal("match_filter_denylist failed"); 180 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 181 if (*pkalg_prop == '\0') 182 fatal("No supported PK algorithms found"); 183 return pkalg_prop; 184 } 185 186 char * 187 compat_kex_proposal(char *p) 188 { 189 if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0) 190 return p; 191 debug2("%s: original KEX proposal: %s", __func__, p); 192 if ((datafellows & SSH_BUG_CURVE25519PAD) != 0) 193 if ((p = match_filter_denylist(p, 194 "curve25519-sha256@libssh.org")) == NULL) 195 fatal("match_filter_denylist failed"); 196 if ((datafellows & SSH_OLD_DHGEX) != 0) { 197 if ((p = match_filter_denylist(p, 198 "diffie-hellman-group-exchange-sha256," 199 "diffie-hellman-group-exchange-sha1")) == NULL) 200 fatal("match_filter_denylist failed"); 201 } 202 debug2("%s: compat KEX proposal: %s", __func__, p); 203 if (*p == '\0') 204 fatal("No supported key exchange algorithms found"); 205 return p; 206 } 207 208