1 /* $OpenBSD: compat.c,v 1.85 2014/04/20 02:49:32 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 "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 void 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 { "*SSH Compatible Server*", /* Netscreen */ 157 SSH_BUG_PASSWORDPAD }, 158 { "*OSU_0*," 159 "OSU_1.0*," 160 "OSU_1.1*," 161 "OSU_1.2*," 162 "OSU_1.3*," 163 "OSU_1.4*," 164 "OSU_1.5alpha1*," 165 "OSU_1.5alpha2*," 166 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 167 { "*SSH_Version_Mapper*", 168 SSH_BUG_SCANNER }, 169 { "Probe-*", 170 SSH_BUG_PROBE }, 171 { NULL, 0 } 172 }; 173 174 /* process table, return first match */ 175 for (i = 0; check[i].pat; i++) { 176 if (match_pattern_list(version, check[i].pat, 177 strlen(check[i].pat), 0) == 1) { 178 datafellows = check[i].bugs; 179 debug("match: %s pat %s compat 0x%08x", 180 version, check[i].pat, datafellows); 181 return; 182 } 183 } 184 debug("no match: %s", version); 185 } 186 187 #define SEP "," 188 int 189 proto_spec(const char *spec) 190 { 191 char *s, *p, *q; 192 int ret = SSH_PROTO_UNKNOWN; 193 194 if (spec == NULL) 195 return ret; 196 q = s = xstrdup(spec); 197 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 198 switch (atoi(p)) { 199 case 1: 200 if (ret == SSH_PROTO_UNKNOWN) 201 ret |= SSH_PROTO_1_PREFERRED; 202 ret |= SSH_PROTO_1; 203 break; 204 case 2: 205 ret |= SSH_PROTO_2; 206 break; 207 default: 208 logit("ignoring bad proto spec: '%s'.", p); 209 break; 210 } 211 } 212 free(s); 213 return ret; 214 } 215 216 /* 217 * Filters a proposal string, excluding any algorithm matching the 'filter' 218 * pattern list. 219 */ 220 static char * 221 filter_proposal(char *proposal, const char *filter) 222 { 223 Buffer b; 224 char *orig_prop, *fix_prop; 225 char *cp, *tmp; 226 227 buffer_init(&b); 228 tmp = orig_prop = xstrdup(proposal); 229 while ((cp = strsep(&tmp, ",")) != NULL) { 230 if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) { 231 if (buffer_len(&b) > 0) 232 buffer_append(&b, ",", 1); 233 buffer_append(&b, cp, strlen(cp)); 234 } else 235 debug2("Compat: skipping algorithm \"%s\"", cp); 236 } 237 buffer_append(&b, "\0", 1); 238 fix_prop = xstrdup(buffer_ptr(&b)); 239 buffer_free(&b); 240 free(orig_prop); 241 242 return fix_prop; 243 } 244 245 char * 246 compat_cipher_proposal(char *cipher_prop) 247 { 248 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 249 return cipher_prop; 250 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 251 cipher_prop = filter_proposal(cipher_prop, "aes*"); 252 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 253 if (*cipher_prop == '\0') 254 fatal("No supported ciphers found"); 255 return cipher_prop; 256 } 257 258 char * 259 compat_pkalg_proposal(char *pkalg_prop) 260 { 261 if (!(datafellows & SSH_BUG_RSASIGMD5)) 262 return pkalg_prop; 263 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 264 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 265 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 266 if (*pkalg_prop == '\0') 267 fatal("No supported PK algorithms found"); 268 return pkalg_prop; 269 } 270 271 char * 272 compat_kex_proposal(char *kex_prop) 273 { 274 if (!(datafellows & SSH_BUG_CURVE25519PAD)) 275 return kex_prop; 276 debug2("%s: original KEX proposal: %s", __func__, kex_prop); 277 kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org"); 278 debug2("%s: compat KEX proposal: %s", __func__, kex_prop); 279 if (*kex_prop == '\0') 280 fatal("No supported key exchange algorithms found"); 281 return kex_prop; 282 } 283 284