compat.c

   1 /* $OpenBSD: compat.c,v 1.100 2017/02/03 23:01:19 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 #include "kex.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_BUG_HOSTKEYS },
 158                 { "*SSH Compatible Server*",                    /* Netscreen */
 159                                         SSH_BUG_PASSWORDPAD },
 160                 { "*OSU_0*,"
 161                   "OSU_1.0*,"
 162                   "OSU_1.1*,"
 163                   "OSU_1.2*,"
 164                   "OSU_1.3*,"
 165                   "OSU_1.4*,"
 166                   "OSU_1.5alpha1*,"
 167                   "OSU_1.5alpha2*,"
 168                   "OSU_1.5alpha3*",     SSH_BUG_PASSWORDPAD },
 169                 { "*SSH_Version_Mapper*",
 170                                         SSH_BUG_SCANNER },
 171                 { "PuTTY_Local:*,"      /* dev versions < Sep 2014 */
 172                   "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
 173                   "PuTTY_Release_0.5*," /* 0.58-0.59 */
 174                   "PuTTY_Release_0.60*,"
 175                   "PuTTY_Release_0.61*,"
 176                   "PuTTY_Release_0.62*,"
 177                   "PuTTY_Release_0.63*,"
 178                   "PuTTY_Release_0.64*",
 179                                         SSH_OLD_DHGEX },
 180                 { "FuTTY*",             SSH_OLD_DHGEX }, /* Putty Fork */
 181                 { "Probe-*",
 182                                         SSH_BUG_PROBE },
 183                 { "TeraTerm SSH*,"
 184                   "TTSSH/1.5.*,"
 185                   "TTSSH/2.1*,"
 186                   "TTSSH/2.2*,"
 187                   "TTSSH/2.3*,"
 188                   "TTSSH/2.4*,"
 189                   "TTSSH/2.5*,"
 190                   "TTSSH/2.6*,"
 191                   "TTSSH/2.70*,"
 192                   "TTSSH/2.71*,"
 193                   "TTSSH/2.72*",        SSH_BUG_HOSTKEYS },
 194                 { "WinSCP_release_4*,"
 195                   "WinSCP_release_5.0*,"
 196                   "WinSCP_release_5.1*,"
 197                   "WinSCP_release_5.5*,"
 198                   "WinSCP_release_5.6*,"
 199                   "WinSCP_release_5.7,"
 200                   "WinSCP_release_5.7.1,"
 201                   "WinSCP_release_5.7.2,"
 202                   "WinSCP_release_5.7.3,"
 203                   "WinSCP_release_5.7.4",
 204                                         SSH_OLD_DHGEX },
 205                 { NULL,                 0 }
 206         };
 207
 208         /* process table, return first match */
 209         for (i = 0; check[i].pat; i++) {
 210                 if (match_pattern_list(version, check[i].pat, 0) == 1) {
 211                         debug("match: %s pat %s compat 0x%08x",
 212                             version, check[i].pat, check[i].bugs);
 213                         datafellows = check[i].bugs;    /* XXX for now */
 214                         return check[i].bugs;
 215                 }
 216         }
 217         debug("no match: %s", version);
 218         return 0;
 219 }
 220
 221 #define SEP     ","
 222 int
 223 proto_spec(const char *spec)
 224 {
 225         char *s, *p, *q;
 226         int ret = SSH_PROTO_UNKNOWN;
 227
 228         if (spec == NULL)
 229                 return ret;
 230         q = s = strdup(spec);
 231         if (s == NULL)
 232                 return ret;
 233         for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
 234                 switch (atoi(p)) {
 235                 case 1:
 236 #ifdef WITH_SSH1
 237                         if (ret == SSH_PROTO_UNKNOWN)
 238                                 ret |= SSH_PROTO_1_PREFERRED;
 239                         ret |= SSH_PROTO_1;
 240 #endif
 241                         break;
 242                 case 2:
 243                         ret |= SSH_PROTO_2;
 244                         break;
 245                 default:
 246                         logit("ignoring bad proto spec: '%s'.", p);
 247                         break;
 248                 }
 249         }
 250         free(s);
 251         return ret;
 252 }
 253
 254 char *
 255 compat_cipher_proposal(char *cipher_prop)
 256 {
 257         if (!(datafellows & SSH_BUG_BIGENDIANAES))
 258                 return cipher_prop;
 259         debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
 260         if ((cipher_prop = match_filter_list(cipher_prop, "aes*")) == NULL)
 261                 fatal("match_filter_list failed");
 262         debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
 263         if (*cipher_prop == '\0')
 264                 fatal("No supported ciphers found");
 265         return cipher_prop;
 266 }
 267
 268 char *
 269 compat_pkalg_proposal(char *pkalg_prop)
 270 {
 271         if (!(datafellows & SSH_BUG_RSASIGMD5))
 272                 return pkalg_prop;
 273         debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
 274         if ((pkalg_prop = match_filter_list(pkalg_prop, "ssh-rsa")) == NULL)
 275                 fatal("match_filter_list failed");
 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 *p)
 284 {
 285         if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
 286                 return p;
 287         debug2("%s: original KEX proposal: %s", __func__, p);
 288         if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
 289                 if ((p = match_filter_list(p,
 290                     "curve25519-sha256@libssh.org")) == NULL)
 291                         fatal("match_filter_list failed");
 292         if ((datafellows & SSH_OLD_DHGEX) != 0) {
 293                 if ((p = match_filter_list(p,
 294                     "diffie-hellman-group-exchange-sha256,"
 295                     "diffie-hellman-group-exchange-sha1")) == NULL)
 296                         fatal("match_filter_list failed");
 297         }
 298         debug2("%s: compat KEX proposal: %s", __func__, p);
 299         if (*p == '\0')
 300                 fatal("No supported key exchange algorithms found");
 301         return p;
 302 }
 303