compat.c revision 294693
1/* $OpenBSD: compat.c,v 1.82 2013/12/30 23:52:27 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 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 41int compat13 = 0; 42int compat20 = 0; 43int datafellows = 0; 44 45void 46enable_compat20(void) 47{ 48 if (compat20) 49 return; 50 debug("Enabling compatibility mode for protocol 2.0"); 51 compat20 = 1; 52} 53void 54enable_compat13(void) 55{ 56 debug("Enabling compatibility mode for protocol 1.3"); 57 compat13 = 1; 58} 59/* datafellows bug compatibility */ 60void 61compat_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 { "*SSH Compatible Server*", /* Netscreen */ 156 SSH_BUG_PASSWORDPAD }, 157 { "*OSU_0*," 158 "OSU_1.0*," 159 "OSU_1.1*," 160 "OSU_1.2*," 161 "OSU_1.3*," 162 "OSU_1.4*," 163 "OSU_1.5alpha1*," 164 "OSU_1.5alpha2*," 165 "OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD }, 166 { "*SSH_Version_Mapper*", 167 SSH_BUG_SCANNER }, 168 { "Probe-*", 169 SSH_BUG_PROBE }, 170 { NULL, 0 } 171 }; 172 173 /* process table, return first match */ 174 for (i = 0; check[i].pat; i++) { 175 if (match_pattern_list(version, check[i].pat, 176 strlen(check[i].pat), 0) == 1) { 177 datafellows = check[i].bugs; 178 debug("match: %s pat %s compat 0x%08x", 179 version, check[i].pat, datafellows); 180 return; 181 } 182 } 183 debug("no match: %s", version); 184} 185 186#define SEP "," 187int 188proto_spec(const char *spec) 189{ 190 char *s, *p, *q; 191 int ret = SSH_PROTO_UNKNOWN; 192 193 if (spec == NULL) 194 return ret; 195 q = s = xstrdup(spec); 196 for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) { 197 switch (atoi(p)) { 198 case 1: 199 if (ret == SSH_PROTO_UNKNOWN) 200 ret |= SSH_PROTO_1_PREFERRED; 201 ret |= SSH_PROTO_1; 202 break; 203 case 2: 204 ret |= SSH_PROTO_2; 205 break; 206 default: 207 logit("ignoring bad proto spec: '%s'.", p); 208 break; 209 } 210 } 211 free(s); 212 return ret; 213} 214 215/* 216 * Filters a proposal string, excluding any algorithm matching the 'filter' 217 * pattern list. 218 */ 219static char * 220filter_proposal(char *proposal, const char *filter) 221{ 222 Buffer b; 223 char *orig_prop, *fix_prop; 224 char *cp, *tmp; 225 226 buffer_init(&b); 227 tmp = orig_prop = xstrdup(proposal); 228 while ((cp = strsep(&tmp, ",")) != NULL) { 229 if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) { 230 if (buffer_len(&b) > 0) 231 buffer_append(&b, ",", 1); 232 buffer_append(&b, cp, strlen(cp)); 233 } else 234 debug2("Compat: skipping algorithm \"%s\"", cp); 235 } 236 buffer_append(&b, "\0", 1); 237 fix_prop = xstrdup(buffer_ptr(&b)); 238 buffer_free(&b); 239 free(orig_prop); 240 241 return fix_prop; 242} 243 244char * 245compat_cipher_proposal(char *cipher_prop) 246{ 247 if (!(datafellows & SSH_BUG_BIGENDIANAES)) 248 return cipher_prop; 249 debug2("%s: original cipher proposal: %s", __func__, cipher_prop); 250 cipher_prop = filter_proposal(cipher_prop, "aes*"); 251 debug2("%s: compat cipher proposal: %s", __func__, cipher_prop); 252 if (*cipher_prop == '\0') 253 fatal("No supported ciphers found"); 254 return cipher_prop; 255} 256 257char * 258compat_pkalg_proposal(char *pkalg_prop) 259{ 260 if (!(datafellows & SSH_BUG_RSASIGMD5)) 261 return pkalg_prop; 262 debug2("%s: original public key proposal: %s", __func__, pkalg_prop); 263 pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa"); 264 debug2("%s: compat public key proposal: %s", __func__, pkalg_prop); 265 if (*pkalg_prop == '\0') 266 fatal("No supported PK algorithms found"); 267 return pkalg_prop; 268} 269 270char * 271compat_kex_proposal(char *kex_prop) 272{ 273 if (!(datafellows & SSH_BUG_CURVE25519PAD)) 274 return kex_prop; 275 debug2("%s: original KEX proposal: %s", __func__, kex_prop); 276 kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org"); 277 debug2("%s: compat KEX proposal: %s", __func__, kex_prop); 278 if (*kex_prop == '\0') 279 fatal("No supported key exchange algorithms found"); 280 return kex_prop; 281} 282 283