crypto/openssh/compat.c

   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