1 /* $OpenBSD: compat.c,v 1.82 2013/12/30 23:52:27 djm Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$FreeBSD$"); 29 30 #include <sys/types.h> 31 32 #include <stdlib.h> 33 #include <string.h> 34 #include <stdarg.h> 35 36 #include "xmalloc.h" 37 #include "buffer.h" 38 #include "packet.h" 39 #include "compat.h" 40 #include "log.h" 41 #include "match.h" 42 43 int compat13 = 0; 44 int compat20 = 0; 45 int datafellows = 0; 46 47 void 48 enable_compat20(void) 49 { 50 if (compat20) 51 return; 52 debug("Enabling compatibility mode for protocol 2.0"); 53 compat20 = 1; 54 } 55 void 56 enable_compat13(void) 57 { 58 debug("Enabling compatibility mode for protocol 1.3"); 59 compat13 = 1; 60 } 61 /* datafellows bug compatibility */ 62 void 63 compat_datafellows(const char *version) 64 { 65 int i; 66 static struct { 67 char *pat; 68 int bugs; 69 } check[] = { 70 { "OpenSSH-2.0*," 71 "OpenSSH-2.1*," 72 "OpenSSH_2.1*," 73 "OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER| 74 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 75 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 76 { "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES| 77 SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 78 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 79 { "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 80 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 81 SSH_OLD_FORWARD_ADDR}, 82 { "OpenSSH_2.5.0p1*," 83 "OpenSSH_2.5.1p1*", 84 SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX| 85 SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 86 SSH_OLD_FORWARD_ADDR}, 87 { "OpenSSH_2.5.0*," 88 "OpenSSH_2.5.1*," 89 "OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY| 90 SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 91 { "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF| 92 SSH_OLD_FORWARD_ADDR}, 93 { "OpenSSH_2.*," 94 "OpenSSH_3.0*," 95 "OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR}, 96 { "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR }, 97 { "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF}, 98 { "OpenSSH_4*", 0 }, 99 { "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT}, 100 { "OpenSSH_6.6.1*", SSH_NEW_OPENSSH}, 101 { "OpenSSH_6.5*," 102 "OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD}, 103 { "OpenSSH*", SSH_NEW_OPENSSH }, 104 { "*MindTerm*", 0 }, 105 { "2.1.0*", 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 { "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 110 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 111 SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE| 112 SSH_BUG_FIRSTKEX }, 113 { "2.0.13*," 114 "2.0.14*," 115 "2.0.15*," 116 "2.0.16*," 117 "2.0.17*," 118 "2.0.18*," 119 "2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 120 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 121 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 122 SSH_BUG_PKOK|SSH_BUG_RSASIGMD5| 123 SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE| 124 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 125 { "2.0.11*," 126 "2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 127 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 128 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 129 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 130 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 131 SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX }, 132 { "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC| 133 SSH_OLD_SESSIONID|SSH_BUG_DEBUG| 134 SSH_BUG_PKSERVICE|SSH_BUG_X11FWD| 135 SSH_BUG_PKAUTH|SSH_BUG_PKOK| 136 SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE| 137 SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN| 138 SSH_BUG_FIRSTKEX }, 139 { "2.2.0*," 140 "2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG| 141 SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX }, 142 { "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5| 143 SSH_BUG_FIRSTKEX }, 144 { "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */ 145 { "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX| 146 SSH_BUG_RFWD_ADDR }, 147 { "3.0.*", SSH_BUG_DEBUG }, 148 { "3.0 SecureCRT*", SSH_OLD_SESSIONID }, 149 { "1.7 SecureFX*", SSH_OLD_SESSIONID }, 150 { "1.2.18*," 151 "1.2.19*," 152 "1.2.20*," 153 "1.2.21*," 154 "1.2.22*", SSH_BUG_IGNOREMSG }, 155 { "1.3.2*", /* F-Secure */ 156 SSH_BUG_IGNOREMSG }, 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 { "Probe-*", 171 SSH_BUG_PROBE }, 172 { NULL, 0 } 173 }; 174 175 /* process table, return first match */ 176 for (i = 0; check[i].pat; i++) { 177 if (match_pattern_list(version, check[i].pat, 178 strlen(check[i].pat), 0) == 1) { 179 datafellows = check[i].bugs; 180 debug("match: %s pat %s compat 0x%08x", 181 version, check[i].pat, datafellows); 182 /* 183 * Check to see if the remote side is OpenSSH and not 184 * HPN. It is utterly strange to check it from the 185 * version string and expose the option that way. 186 */ 187 if (strstr(version,"OpenSSH") != NULL && 188 strstr(version,"hpn") == NULL) { 189 datafellows |= SSH_BUG_LARGEWINDOW; 190 debug("Remote is not HPN-aware"); 191 } 192 return; 193 } 194 } 195 debug("no match: %s", version); 196 } 197 198 #define SEP "," 199 int 200 proto_spec(const char *spec) 201 { 202 char *s, *p, *q; 203 int ret = SSH_PROTO_UNKNOWN; 204 205 if (spec == NULL) 206 return ret; 207 q = s = xstrdup(spec); 208 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 209 switch (atoi(p)) { 210 case 1: 211 if (ret == SSH_PROTO_UNKNOWN) 212 ret |= SSH_PROTO_1_PREFERRED; 213 ret |= SSH_PROTO_1; 214 break; 215 case 2: 216 ret |= SSH_PROTO_2; 217 break; 218 default: 219 logit("ignoring bad proto spec: '%s'.", p); 220 break; 221 } 222 } 223 free(s); 224 return ret; 225 } 226 227 /* 228 * Filters a proposal string, excluding any algorithm matching the 'filter' 229 * pattern list. 230 */ 231 static char * 232 filter_proposal(char *proposal, const char *filter) 233 { 234 Buffer b; 235 char *orig_prop, *fix_prop; 236 char *cp, *tmp; 237 238 buffer_init(&b); 239 tmp = orig_prop = xstrdup(proposal); 240 while ((cp = strsep(&tmp, ",")) != NULL) { 241 if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) { 242 if (buffer_len(&b) > 0) 243 buffer_append(&b, ",", 1); 244 buffer_append(&b, cp, strlen(cp)); 245 } else 246 debug2("Compat: skipping algorithm \"%s\"", cp); 247 } 248 buffer_append(&b, "\0", 1); 249 fix_prop = xstrdup(buffer_ptr(&b)); 250 buffer_free(&b); 251 free(orig_prop); 252 253 return fix_prop; 254 } 255 256 char * 257 compat_cipher_proposal(char *cipher_prop) 258 { 259 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 260 return cipher_prop; 261 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 262 cipher_prop = filter_proposal(cipher_prop, "aes*"); 263 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 264 if (*cipher_prop == '\0') 265 fatal("No supported ciphers found"); 266 return cipher_prop; 267 } 268 269 char * 270 compat_pkalg_proposal(char *pkalg_prop) 271 { 272 if (!(datafellows & SSH_BUG_RSASIGMD5)) 273 return pkalg_prop; 274 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 275 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 276 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 277 if (*pkalg_prop == '\0') 278 fatal("No supported PK algorithms found"); 279 return pkalg_prop; 280 } 281 282 char * 283 compat_kex_proposal(char *kex_prop) 284 { 285 if (!(datafellows & SSH_BUG_CURVE25519PAD)) 286 return kex_prop; 287 debug2("%s: original KEX proposal: %s", __func__, kex_prop); 288 kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org"); 289 debug2("%s: compat KEX proposal: %s", __func__, kex_prop); 290 if (*kex_prop == '\0') 291 fatal("No supported key exchange algorithms found"); 292 return kex_prop; 293 } 294 295