1 /* $OpenBSD: compat.c,v 1.93 2015/05/06 04:07:18 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 "buffer.h" 34 #include "packet.h" 35 #include "compat.h" 36 #include "log.h" 37 #include "match.h" 38 39 int compat13 = 0; 40 int compat20 = 0; 41 int datafellows = 0; 42 43 void 44 enable_compat20(void) 45 { 46 if (compat20) 47 return; 48 debug("Enabling compatibility mode for protocol 2.0"); 49 compat20 = 1; 50 } 51 void 52 enable_compat13(void) 53 { 54 debug("Enabling compatibility mode for protocol 1.3"); 55 compat13 = 1; 56 } 57 /* datafellows bug compatibility */ 58 u_int 59 compat_datafellows(const char *version) 60 { 61 int i; 62 static struct { 63 char *pat; 64 int bugs; 65 } check[] = { 66 { "OpenSSH-2.0*," 67 "OpenSSH-2.1*," 68 "OpenSSH_2.1*," 69 "OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER| 70 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 71 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 72 { "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES| 73 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 74 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 75 { "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 76 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 77 SSH_OLD_FORWARD_ADDR}, 78 { "OpenSSH_2.5.0p1*," 79 "OpenSSH_2.5.1p1*", 80 SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 81 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 82 SSH_OLD_FORWARD_ADDR}, 83 { "OpenSSH_2.5.0*," 84 "OpenSSH_2.5.1*," 85 "OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 86 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 87 { "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 88 SSH_OLD_FORWARD_ADDR}, 89 { "OpenSSH_2.*," 90 "OpenSSH_3.0*," 91 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 92 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR }, 93 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF}, 94 { "OpenSSH_4*", 0 }, 95 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT}, 96 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH}, 97 { "OpenSSH_6.5*," 98 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD}, 99 { "OpenSSH*", SSH_NEW_OPENSSH }, 100 { "*MindTerm*", 0 }, 101 { "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 102 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 103 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 104 SSH_BUG_FIRSTKEX }, 105 { "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 106 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 107 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 108 SSH_BUG_FIRSTKEX }, 109 { "2.0.13*," 110 "2.0.14*," 111 "2.0.15*," 112 "2.0.16*," 113 "2.0.17*," 114 "2.0.18*," 115 "2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 116 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 117 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 118 SSH_BUG_PKOK|SSH_BUG_RSASIGMD5| 119 SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE| 120 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 121 { "2.0.11*," 122 "2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 123 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 124 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 125 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 126 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 127 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 128 { "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 129 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 130 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 131 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 132 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 133 SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN| 134 SSH_BUG_FIRSTKEX }, 135 { "2.2.0*," 136 "2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG| 137 SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX }, 138 { "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5| 139 SSH_BUG_FIRSTKEX }, 140 { "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */ 141 { "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX| 142 SSH_BUG_RFWD_ADDR }, 143 { "3.0.*", SSH_BUG_DEBUG }, 144 { "3.0 SecureCRT*", SSH_OLD_SESSIONID }, 145 { "1.7 SecureFX*", SSH_OLD_SESSIONID }, 146 { "1.2.18*," 147 "1.2.19*," 148 "1.2.20*," 149 "1.2.21*," 150 "1.2.22*", SSH_BUG_IGNOREMSG }, 151 { "1.3.2*", /* F-Secure */ 152 SSH_BUG_IGNOREMSG }, 153 { "*SSH Compatible Server*", /* Netscreen */ 154 SSH_BUG_PASSWORDPAD }, 155 { "*OSU_0*," 156 "OSU_1.0*," 157 "OSU_1.1*," 158 "OSU_1.2*," 159 "OSU_1.3*," 160 "OSU_1.4*," 161 "OSU_1.5alpha1*," 162 "OSU_1.5alpha2*," 163 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 164 { "*SSH_Version_Mapper*", 165 SSH_BUG_SCANNER }, 166 { "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */ 167 "PuTTY_Release_0.5*," /* 0.58-0.59 */ 168 "PuTTY_Release_0.60*," 169 "PuTTY_Release_0.61*," 170 "PuTTY_Release_0.62*," 171 "PuTTY_Release_0.63*," 172 "PuTTY_Release_0.64*", 173 SSH_OLD_DHGEX }, 174 { "Probe-*", 175 SSH_BUG_PROBE }, 176 { "TeraTerm SSH*," 177 "TTSSH/1.5.*," 178 "TTSSH/2.1*," 179 "TTSSH/2.2*," 180 "TTSSH/2.3*," 181 "TTSSH/2.4*," 182 "TTSSH/2.5*," 183 "TTSSH/2.6*," 184 "TTSSH/2.70*," 185 "TTSSH/2.71*," 186 "TTSSH/2.72*", SSH_BUG_HOSTKEYS }, 187 { "WinSCP*", SSH_OLD_DHGEX }, 188 { NULL, 0 } 189 }; 190 191 /* process table, return first match */ 192 for (i = 0; check[i].pat; i++) { 193 if (match_pattern_list(version, check[i].pat, 0) == 1) { 194 debug("match: %s pat %s compat 0x%08x", 195 version, check[i].pat, check[i].bugs); 196 datafellows = check[i].bugs; /* XXX for now */ 197 return check[i].bugs; 198 } 199 } 200 debug("no match: %s", version); 201 return 0; 202 } 203 204 #define SEP "," 205 int 206 proto_spec(const char *spec) 207 { 208 char *s, *p, *q; 209 int ret = SSH_PROTO_UNKNOWN; 210 211 if (spec == NULL) 212 return ret; 213 q = s = strdup(spec); 214 if (s == NULL) 215 return ret; 216 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 217 switch (atoi(p)) { 218 case 1: 219 #ifdef WITH_SSH1 220 if (ret == SSH_PROTO_UNKNOWN) 221 ret |= SSH_PROTO_1_PREFERRED; 222 ret |= SSH_PROTO_1; 223 #endif 224 break; 225 case 2: 226 ret |= SSH_PROTO_2; 227 break; 228 default: 229 logit("ignoring bad proto spec: '%s'.", p); 230 break; 231 } 232 } 233 free(s); 234 return ret; 235 } 236 237 /* 238 * Filters a proposal string, excluding any algorithm matching the 'filter' 239 * pattern list. 240 */ 241 static char * 242 filter_proposal(char *proposal, const char *filter) 243 { 244 Buffer b; 245 char *orig_prop, *fix_prop; 246 char *cp, *tmp; 247 248 buffer_init(&b); 249 tmp = orig_prop = xstrdup(proposal); 250 while ((cp = strsep(&tmp, ",")) != NULL) { 251 if (match_pattern_list(cp, filter, 0) != 1) { 252 if (buffer_len(&b) > 0) 253 buffer_append(&b, ",", 1); 254 buffer_append(&b, cp, strlen(cp)); 255 } else 256 debug2("Compat: skipping algorithm \"%s\"", cp); 257 } 258 buffer_append(&b, "\0", 1); 259 fix_prop = xstrdup((char *)buffer_ptr(&b)); 260 buffer_free(&b); 261 free(orig_prop); 262 263 return fix_prop; 264 } 265 266 char * 267 compat_cipher_proposal(char *cipher_prop) 268 { 269 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 270 return cipher_prop; 271 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 272 cipher_prop = filter_proposal(cipher_prop, "aes*"); 273 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 274 if (*cipher_prop == '\0') 275 fatal("No supported ciphers found"); 276 return cipher_prop; 277 } 278 279 char * 280 compat_pkalg_proposal(char *pkalg_prop) 281 { 282 if (!(datafellows & SSH_BUG_RSASIGMD5)) 283 return pkalg_prop; 284 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 285 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 286 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 287 if (*pkalg_prop == '\0') 288 fatal("No supported PK algorithms found"); 289 return pkalg_prop; 290 } 291 292 char * 293 compat_kex_proposal(char *p) 294 { 295 if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0) 296 return p; 297 debug2("%s: original KEX proposal: %s", __func__, p); 298 if ((datafellows & SSH_BUG_CURVE25519PAD) != 0) 299 p = filter_proposal(p, "curve25519-sha256@libssh.org"); 300 if ((datafellows & SSH_OLD_DHGEX) != 0) { 301 p = filter_proposal(p, "diffie-hellman-group-exchange-sha256"); 302 p = filter_proposal(p, "diffie-hellman-group-exchange-sha1"); 303 } 304 debug2("%s: compat KEX proposal: %s", __func__, p); 305 if (*p == '\0') 306 fatal("No supported key exchange algorithms found"); 307 return p; 308 } 309 310