1 /* $OpenBSD: compat.c,v 1.94 2015/05/26 23:23:40 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 __RCSID("$FreeBSD$"); 28 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 "buffer.h" 37 #include "packet.h" 38 #include "compat.h" 39 #include "log.h" 40 #include "match.h" 41 42 int compat13 = 0; 43 int compat20 = 0; 44 int datafellows = 0; 45 46 void 47 enable_compat20(void) 48 { 49 if (compat20) 50 return; 51 debug("Enabling compatibility mode for protocol 2.0"); 52 compat20 = 1; 53 } 54 void 55 enable_compat13(void) 56 { 57 debug("Enabling compatibility mode for protocol 1.3"); 58 compat13 = 1; 59 } 60 /* datafellows bug compatibility */ 61 u_int 62 compat_datafellows(const char *version) 63 { 64 int i; 65 static struct { 66 char *pat; 67 int bugs; 68 } check[] = { 69 { "OpenSSH-2.0*," 70 "OpenSSH-2.1*," 71 "OpenSSH_2.1*," 72 "OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER| 73 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 74 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 75 { "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES| 76 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 77 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 78 { "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 79 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 80 SSH_OLD_FORWARD_ADDR}, 81 { "OpenSSH_2.5.0p1*," 82 "OpenSSH_2.5.1p1*", 83 SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 84 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 85 SSH_OLD_FORWARD_ADDR}, 86 { "OpenSSH_2.5.0*," 87 "OpenSSH_2.5.1*," 88 "OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 89 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 90 { "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 91 SSH_OLD_FORWARD_ADDR}, 92 { "OpenSSH_2.*," 93 "OpenSSH_3.0*," 94 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 95 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR }, 96 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF}, 97 { "OpenSSH_4*", 0 }, 98 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT}, 99 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH}, 100 { "OpenSSH_6.5*," 101 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD}, 102 { "OpenSSH*", SSH_NEW_OPENSSH }, 103 { "*MindTerm*", 0 }, 104 { "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 105 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 106 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 107 SSH_BUG_FIRSTKEX }, 108 { "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 109 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 110 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 111 SSH_BUG_FIRSTKEX }, 112 { "2.0.13*," 113 "2.0.14*," 114 "2.0.15*," 115 "2.0.16*," 116 "2.0.17*," 117 "2.0.18*," 118 "2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 119 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 120 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 121 SSH_BUG_PKOK|SSH_BUG_RSASIGMD5| 122 SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE| 123 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 124 { "2.0.11*," 125 "2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 126 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 127 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 128 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 129 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 130 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 131 { "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 132 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 133 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 134 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 135 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 136 SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN| 137 SSH_BUG_FIRSTKEX }, 138 { "2.2.0*," 139 "2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG| 140 SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX }, 141 { "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5| 142 SSH_BUG_FIRSTKEX }, 143 { "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */ 144 { "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX| 145 SSH_BUG_RFWD_ADDR }, 146 { "3.0.*", SSH_BUG_DEBUG }, 147 { "3.0 SecureCRT*", SSH_OLD_SESSIONID }, 148 { "1.7 SecureFX*", SSH_OLD_SESSIONID }, 149 { "1.2.18*," 150 "1.2.19*," 151 "1.2.20*," 152 "1.2.21*," 153 "1.2.22*", SSH_BUG_IGNOREMSG }, 154 { "1.3.2*", /* F-Secure */ 155 SSH_BUG_IGNOREMSG }, 156 { "Cisco-1.*", SSH_BUG_DHGEX_LARGE }, 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-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */ 171 "PuTTY_Release_0.5*," /* 0.58-0.59 */ 172 "PuTTY_Release_0.60*," 173 "PuTTY_Release_0.61*," 174 "PuTTY_Release_0.62*," 175 "PuTTY_Release_0.63*," 176 "PuTTY_Release_0.64*", 177 SSH_OLD_DHGEX }, 178 { "Probe-*", 179 SSH_BUG_PROBE }, 180 { "TeraTerm SSH*," 181 "TTSSH/1.5.*," 182 "TTSSH/2.1*," 183 "TTSSH/2.2*," 184 "TTSSH/2.3*," 185 "TTSSH/2.4*," 186 "TTSSH/2.5*," 187 "TTSSH/2.6*," 188 "TTSSH/2.70*," 189 "TTSSH/2.71*," 190 "TTSSH/2.72*", SSH_BUG_HOSTKEYS }, 191 { "WinSCP*", SSH_OLD_DHGEX }, 192 { NULL, 0 } 193 }; 194 195 /* process table, return first match */ 196 for (i = 0; check[i].pat; i++) { 197 if (match_pattern_list(version, check[i].pat, 0) == 1) { 198 debug("match: %s pat %s compat 0x%08x", 199 version, check[i].pat, check[i].bugs); 200 datafellows = check[i].bugs; /* XXX for now */ 201 return check[i].bugs; 202 } 203 } 204 debug("no match: %s", version); 205 return 0; 206 } 207 208 #define SEP "," 209 int 210 proto_spec(const char *spec) 211 { 212 char *s, *p, *q; 213 int ret = SSH_PROTO_UNKNOWN; 214 215 if (spec == NULL) 216 return ret; 217 q = s = strdup(spec); 218 if (s == NULL) 219 return ret; 220 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 221 switch (atoi(p)) { 222 case 1: 223 #ifdef WITH_SSH1 224 if (ret == SSH_PROTO_UNKNOWN) 225 ret |= SSH_PROTO_1_PREFERRED; 226 ret |= SSH_PROTO_1; 227 #endif 228 break; 229 case 2: 230 ret |= SSH_PROTO_2; 231 break; 232 default: 233 logit("ignoring bad proto spec: '%s'.", p); 234 break; 235 } 236 } 237 free(s); 238 return ret; 239 } 240 241 /* 242 * Filters a proposal string, excluding any algorithm matching the 'filter' 243 * pattern list. 244 */ 245 static char * 246 filter_proposal(char *proposal, const char *filter) 247 { 248 Buffer b; 249 char *orig_prop, *fix_prop; 250 char *cp, *tmp; 251 252 buffer_init(&b); 253 tmp = orig_prop = xstrdup(proposal); 254 while ((cp = strsep(&tmp, ",")) != NULL) { 255 if (match_pattern_list(cp, filter, 0) != 1) { 256 if (buffer_len(&b) > 0) 257 buffer_append(&b, ",", 1); 258 buffer_append(&b, cp, strlen(cp)); 259 } else 260 debug2("Compat: skipping algorithm \"%s\"", cp); 261 } 262 buffer_append(&b, "\0", 1); 263 fix_prop = xstrdup((char *)buffer_ptr(&b)); 264 buffer_free(&b); 265 free(orig_prop); 266 267 return fix_prop; 268 } 269 270 char * 271 compat_cipher_proposal(char *cipher_prop) 272 { 273 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 274 return cipher_prop; 275 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 276 cipher_prop = filter_proposal(cipher_prop, "aes*"); 277 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 278 if (*cipher_prop == '\0') 279 fatal("No supported ciphers found"); 280 return cipher_prop; 281 } 282 283 char * 284 compat_pkalg_proposal(char *pkalg_prop) 285 { 286 if (!(datafellows & SSH_BUG_RSASIGMD5)) 287 return pkalg_prop; 288 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 289 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 290 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 291 if (*pkalg_prop == '\0') 292 fatal("No supported PK algorithms found"); 293 return pkalg_prop; 294 } 295 296 char * 297 compat_kex_proposal(char *p) 298 { 299 if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0) 300 return p; 301 debug2("%s: original KEX proposal: %s", __func__, p); 302 if ((datafellows & SSH_BUG_CURVE25519PAD) != 0) 303 p = filter_proposal(p, "curve25519-sha256@libssh.org"); 304 if ((datafellows & SSH_OLD_DHGEX) != 0) { 305 p = filter_proposal(p, "diffie-hellman-group-exchange-sha256"); 306 p = filter_proposal(p, "diffie-hellman-group-exchange-sha1"); 307 } 308 debug2("%s: compat KEX proposal: %s", __func__, p); 309 if (*p == '\0') 310 fatal("No supported key exchange algorithms found"); 311 return p; 312 } 313 314