1 /* $OpenBSD: compat.c,v 1.99 2016/05/24 02:31:57 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 "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 "buffer.h" 36 #include "packet.h" 37 #include "compat.h" 38 #include "log.h" 39 #include "match.h" 40 41 int compat13 = 0; 42 int compat20 = 0; 43 int datafellows = 0; 44 45 void 46 enable_compat20(void) 47 { 48 if (compat20) 49 return; 50 debug("Enabling compatibility mode for protocol 2.0"); 51 compat20 = 1; 52 } 53 void 54 enable_compat13(void) 55 { 56 debug("Enabling compatibility mode for protocol 1.3"); 57 compat13 = 1; 58 } 59 /* datafellows bug compatibility */ 60 u_int 61 compat_datafellows(const char *version) 62 { 63 int i; 64 static struct { 65 char *pat; 66 int bugs; 67 } check[] = { 68 { "OpenSSH-2.0*," 69 "OpenSSH-2.1*," 70 "OpenSSH_2.1*," 71 "OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER| 72 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 73 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 74 { "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES| 75 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 76 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 77 { "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 78 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 79 SSH_OLD_FORWARD_ADDR}, 80 { "OpenSSH_2.5.0p1*," 81 "OpenSSH_2.5.1p1*", 82 SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 83 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 84 SSH_OLD_FORWARD_ADDR}, 85 { "OpenSSH_2.5.0*," 86 "OpenSSH_2.5.1*," 87 "OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 88 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 89 { "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 90 SSH_OLD_FORWARD_ADDR}, 91 { "OpenSSH_2.*," 92 "OpenSSH_3.0*," 93 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 94 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR }, 95 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF}, 96 { "OpenSSH_4*", 0 }, 97 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT}, 98 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH}, 99 { "OpenSSH_6.5*," 100 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD}, 101 { "OpenSSH*", SSH_NEW_OPENSSH }, 102 { "*MindTerm*", 0 }, 103 { "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 104 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 105 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 106 SSH_BUG_FIRSTKEX }, 107 { "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 108 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 109 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 110 SSH_BUG_FIRSTKEX }, 111 { "2.0.13*," 112 "2.0.14*," 113 "2.0.15*," 114 "2.0.16*," 115 "2.0.17*," 116 "2.0.18*," 117 "2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 118 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 119 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 120 SSH_BUG_PKOK|SSH_BUG_RSASIGMD5| 121 SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE| 122 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 123 { "2.0.11*," 124 "2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 125 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 126 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 127 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 128 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 129 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 130 { "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 131 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 132 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 133 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 134 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 135 SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN| 136 SSH_BUG_FIRSTKEX }, 137 { "2.2.0*," 138 "2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG| 139 SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX }, 140 { "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5| 141 SSH_BUG_FIRSTKEX }, 142 { "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */ 143 { "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX| 144 SSH_BUG_RFWD_ADDR }, 145 { "3.0.*", SSH_BUG_DEBUG }, 146 { "3.0 SecureCRT*", SSH_OLD_SESSIONID }, 147 { "1.7 SecureFX*", SSH_OLD_SESSIONID }, 148 { "1.2.18*," 149 "1.2.19*," 150 "1.2.20*," 151 "1.2.21*," 152 "1.2.22*", SSH_BUG_IGNOREMSG }, 153 { "1.3.2*", /* F-Secure */ 154 SSH_BUG_IGNOREMSG }, 155 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE| 156 SSH_BUG_HOSTKEYS }, 157 { "*SSH Compatible Server*", /* Netscreen */ 158 SSH_BUG_PASSWORDPAD }, 159 { "*OSU_0*," 160 "OSU_1.0*," 161 "OSU_1.1*," 162 "OSU_1.2*," 163 "OSU_1.3*," 164 "OSU_1.4*," 165 "OSU_1.5alpha1*," 166 "OSU_1.5alpha2*," 167 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 168 { "*SSH_Version_Mapper*", 169 SSH_BUG_SCANNER }, 170 { "PuTTY_Local:*," /* dev versions < Sep 2014 */ 171 "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */ 172 "PuTTY_Release_0.5*," /* 0.58-0.59 */ 173 "PuTTY_Release_0.60*," 174 "PuTTY_Release_0.61*," 175 "PuTTY_Release_0.62*," 176 "PuTTY_Release_0.63*," 177 "PuTTY_Release_0.64*", 178 SSH_OLD_DHGEX }, 179 { "FuTTY*", SSH_OLD_DHGEX }, /* Putty Fork */ 180 { "Probe-*", 181 SSH_BUG_PROBE }, 182 { "TeraTerm SSH*," 183 "TTSSH/1.5.*," 184 "TTSSH/2.1*," 185 "TTSSH/2.2*," 186 "TTSSH/2.3*," 187 "TTSSH/2.4*," 188 "TTSSH/2.5*," 189 "TTSSH/2.6*," 190 "TTSSH/2.70*," 191 "TTSSH/2.71*," 192 "TTSSH/2.72*", SSH_BUG_HOSTKEYS }, 193 { "WinSCP_release_4*," 194 "WinSCP_release_5.0*," 195 "WinSCP_release_5.1*," 196 "WinSCP_release_5.5*," 197 "WinSCP_release_5.6*," 198 "WinSCP_release_5.7," 199 "WinSCP_release_5.7.1," 200 "WinSCP_release_5.7.2," 201 "WinSCP_release_5.7.3," 202 "WinSCP_release_5.7.4", 203 SSH_OLD_DHGEX }, 204 { NULL, 0 } 205 }; 206 207 /* process table, return first match */ 208 for (i = 0; check[i].pat; i++) { 209 if (match_pattern_list(version, check[i].pat, 0) == 1) { 210 debug("match: %s pat %s compat 0x%08x", 211 version, check[i].pat, check[i].bugs); 212 datafellows = check[i].bugs; /* XXX for now */ 213 return check[i].bugs; 214 } 215 } 216 debug("no match: %s", version); 217 return 0; 218 } 219 220 #define SEP "," 221 int 222 proto_spec(const char *spec) 223 { 224 char *s, *p, *q; 225 int ret = SSH_PROTO_UNKNOWN; 226 227 if (spec == NULL) 228 return ret; 229 q = s = strdup(spec); 230 if (s == NULL) 231 return ret; 232 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 233 switch (atoi(p)) { 234 case 1: 235 #ifdef WITH_SSH1 236 if (ret == SSH_PROTO_UNKNOWN) 237 ret |= SSH_PROTO_1_PREFERRED; 238 ret |= SSH_PROTO_1; 239 #endif 240 break; 241 case 2: 242 ret |= SSH_PROTO_2; 243 break; 244 default: 245 logit("ignoring bad proto spec: '%s'.", p); 246 break; 247 } 248 } 249 free(s); 250 return ret; 251 } 252 253 /* 254 * Filters a proposal string, excluding any algorithm matching the 'filter' 255 * pattern list. 256 */ 257 static char * 258 filter_proposal(char *proposal, const char *filter) 259 { 260 Buffer b; 261 char *orig_prop, *fix_prop; 262 char *cp, *tmp; 263 264 buffer_init(&b); 265 tmp = orig_prop = xstrdup(proposal); 266 while ((cp = strsep(&tmp, ",")) != NULL) { 267 if (match_pattern_list(cp, filter, 0) != 1) { 268 if (buffer_len(&b) > 0) 269 buffer_append(&b, ",", 1); 270 buffer_append(&b, cp, strlen(cp)); 271 } else 272 debug2("Compat: skipping algorithm \"%s\"", cp); 273 } 274 buffer_append(&b, "\0", 1); 275 fix_prop = xstrdup((char *)buffer_ptr(&b)); 276 buffer_free(&b); 277 free(orig_prop); 278 279 return fix_prop; 280 } 281 282 char * 283 compat_cipher_proposal(char *cipher_prop) 284 { 285 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 286 return cipher_prop; 287 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 288 cipher_prop = filter_proposal(cipher_prop, "aes*"); 289 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 290 if (*cipher_prop == '\0') 291 fatal("No supported ciphers found"); 292 return cipher_prop; 293 } 294 295 char * 296 compat_pkalg_proposal(char *pkalg_prop) 297 { 298 if (!(datafellows & SSH_BUG_RSASIGMD5)) 299 return pkalg_prop; 300 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 301 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 302 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 303 if (*pkalg_prop == '\0') 304 fatal("No supported PK algorithms found"); 305 return pkalg_prop; 306 } 307 308 char * 309 compat_kex_proposal(char *p) 310 { 311 if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0) 312 return p; 313 debug2("%s: original KEX proposal: %s", __func__, p); 314 if ((datafellows & SSH_BUG_CURVE25519PAD) != 0) 315 p = filter_proposal(p, "curve25519-sha256@libssh.org"); 316 if ((datafellows & SSH_OLD_DHGEX) != 0) { 317 p = filter_proposal(p, "diffie-hellman-group-exchange-sha256"); 318 p = filter_proposal(p, "diffie-hellman-group-exchange-sha1"); 319 } 320 debug2("%s: compat KEX proposal: %s", __func__, p); 321 if (*p == '\0') 322 fatal("No supported key exchange algorithms found"); 323 return p; 324 } 325 326