crypto/openssh/compat.c

   1 /* $OpenBSD: compat.c,v 1.99 2016/05/24 02:31:57 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
  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
  41 int compat13 = 0;
  42 int compat20 = 0;
  43 int datafellows = 0;
  44
  45 void
  46 enable_compat20(void)
  47 {
  48         if (compat20)
  49                 return;
  50         debug("Enabling compatibility mode for protocol 2.0");
  51         compat20 = 1;
  52 }
  53 void
  54 enable_compat13(void)
  55 {
  56         debug("Enabling compatibility mode for protocol 1.3");
  57         compat13 = 1;
  58 }
  59 /* datafellows bug compatibility */
  60 u_int
  61 compat_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                 { "Cisco-1.*",          SSH_BUG_DHGEX_LARGE|
 156                                         SSH_BUG_HOSTKEYS },
 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_Local:*,"      /* dev versions < Sep 2014 */
 171                   "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
 172                   "PuTTY_Release_0.5*," /* 0.58-0.59 */
 173                   "PuTTY_Release_0.60*,"
 174                   "PuTTY_Release_0.61*,"
 175                   "PuTTY_Release_0.62*,"
 176                   "PuTTY_Release_0.63*,"
 177                   "PuTTY_Release_0.64*",
 178                                         SSH_OLD_DHGEX },
 179                 { "FuTTY*",             SSH_OLD_DHGEX }, /* Putty Fork */
 180                 { "Probe-*",
 181                                         SSH_BUG_PROBE },
 182                 { "TeraTerm SSH*,"
 183                   "TTSSH/1.5.*,"
 184                   "TTSSH/2.1*,"
 185                   "TTSSH/2.2*,"
 186                   "TTSSH/2.3*,"
 187                   "TTSSH/2.4*,"
 188                   "TTSSH/2.5*,"
 189                   "TTSSH/2.6*,"
 190                   "TTSSH/2.70*,"
 191                   "TTSSH/2.71*,"
 192                   "TTSSH/2.72*",        SSH_BUG_HOSTKEYS },
 193                 { "WinSCP_release_4*,"
 194                   "WinSCP_release_5.0*,"
 195                   "WinSCP_release_5.1*,"
 196                   "WinSCP_release_5.5*,"
 197                   "WinSCP_release_5.6*,"
 198                   "WinSCP_release_5.7,"
 199                   "WinSCP_release_5.7.1,"
 200                   "WinSCP_release_5.7.2,"
 201                   "WinSCP_release_5.7.3,"
 202                   "WinSCP_release_5.7.4",
 203                                         SSH_OLD_DHGEX },
 204                 { NULL,                 0 }
 205         };
 206
 207         /* process table, return first match */
 208         for (i = 0; check[i].pat; i++) {
 209                 if (match_pattern_list(version, check[i].pat, 0) == 1) {
 210                         debug("match: %s pat %s compat 0x%08x",
 211                             version, check[i].pat, check[i].bugs);
 212                         datafellows = check[i].bugs;    /* XXX for now */
 213                         return check[i].bugs;
 214                 }
 215         }
 216         debug("no match: %s", version);
 217         return 0;
 218 }
 219
 220 #define SEP     ","
 221 int
 222 proto_spec(const char *spec)
 223 {
 224         char *s, *p, *q;
 225         int ret = SSH_PROTO_UNKNOWN;
 226
 227         if (spec == NULL)
 228                 return ret;
 229         q = s = strdup(spec);
 230         if (s == NULL)
 231                 return ret;
 232         for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
 233                 switch (atoi(p)) {
 234                 case 1:
 235 #ifdef WITH_SSH1
 236                         if (ret == SSH_PROTO_UNKNOWN)
 237                                 ret |= SSH_PROTO_1_PREFERRED;
 238                         ret |= SSH_PROTO_1;
 239 #endif
 240                         break;
 241                 case 2:
 242                         ret |= SSH_PROTO_2;
 243                         break;
 244                 default:
 245                         logit("ignoring bad proto spec: '%s'.", p);
 246                         break;
 247                 }
 248         }
 249         free(s);
 250         return ret;
 251 }
 252
 253 /*
 254  * Filters a proposal string, excluding any algorithm matching the 'filter'
 255  * pattern list.
 256  */
 257 static char *
 258 filter_proposal(char *proposal, const char *filter)
 259 {
 260         Buffer b;
 261         char *orig_prop, *fix_prop;
 262         char *cp, *tmp;
 263
 264         buffer_init(&b);
 265         tmp = orig_prop = xstrdup(proposal);
 266         while ((cp = strsep(&tmp, ",")) != NULL) {
 267                 if (match_pattern_list(cp, filter, 0) != 1) {
 268                         if (buffer_len(&b) > 0)
 269                                 buffer_append(&b, ",", 1);
 270                         buffer_append(&b, cp, strlen(cp));
 271                 } else
 272                         debug2("Compat: skipping algorithm \"%s\"", cp);
 273         }
 274         buffer_append(&b, "\0", 1);
 275         fix_prop = xstrdup((char *)buffer_ptr(&b));
 276         buffer_free(&b);
 277         free(orig_prop);
 278
 279         return fix_prop;
 280 }
 281
 282 char *
 283 compat_cipher_proposal(char *cipher_prop)
 284 {
 285         if (!(datafellows & SSH_BUG_BIGENDIANAES))
 286                 return cipher_prop;
 287         debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
 288         cipher_prop = filter_proposal(cipher_prop, "aes*");
 289         debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
 290         if (*cipher_prop == '\0')
 291                 fatal("No supported ciphers found");
 292         return cipher_prop;
 293 }
 294
 295 char *
 296 compat_pkalg_proposal(char *pkalg_prop)
 297 {
 298         if (!(datafellows & SSH_BUG_RSASIGMD5))
 299                 return pkalg_prop;
 300         debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
 301         pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
 302         debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
 303         if (*pkalg_prop == '\0')
 304                 fatal("No supported PK algorithms found");
 305         return pkalg_prop;
 306 }
 307
 308 char *
 309 compat_kex_proposal(char *p)
 310 {
 311         if ((datafellows & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
 312                 return p;
 313         debug2("%s: original KEX proposal: %s", __func__, p);
 314         if ((datafellows & SSH_BUG_CURVE25519PAD) != 0)
 315                 p = filter_proposal(p, "curve25519-sha256@libssh.org");
 316         if ((datafellows & SSH_OLD_DHGEX) != 0) {
 317                 p = filter_proposal(p, "diffie-hellman-group-exchange-sha256");
 318                 p = filter_proposal(p, "diffie-hellman-group-exchange-sha1");
 319         }
 320         debug2("%s: compat KEX proposal: %s", __func__, p);
 321         if (*p == '\0')
 322                 fatal("No supported key exchange algorithms found");
 323         return p;
 324 }
 325