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
  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                         /*
 182                          * Check to see if the remote side is OpenSSH and not
 183                          * HPN.  It is utterly strange to check it from the
 184                          * version string and expose the option that way.
 185                          */
 186                         if (strstr(version,"OpenSSH") != NULL &&
 187                             strstr(version,"hpn") == NULL) {
 188                                 datafellows |= SSH_BUG_LARGEWINDOW;
 189                                 debug("Remote is not HPN-aware");
 190                         }
 191                         return;
 192                 }
 193         }
 194         debug("no match: %s", version);
 195 }
 196
 197 #define SEP     ","
 198 int
 199 proto_spec(const char *spec)
 200 {
 201         char *s, *p, *q;
 202         int ret = SSH_PROTO_UNKNOWN;
 203
 204         if (spec == NULL)
 205                 return ret;
 206         q = s = xstrdup(spec);
 207         for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
 208                 switch (atoi(p)) {
 209                 case 1:
 210                         if (ret == SSH_PROTO_UNKNOWN)
 211                                 ret |= SSH_PROTO_1_PREFERRED;
 212                         ret |= SSH_PROTO_1;
 213                         break;
 214                 case 2:
 215                         ret |= SSH_PROTO_2;
 216                         break;
 217                 default:
 218                         logit("ignoring bad proto spec: '%s'.", p);
 219                         break;
 220                 }
 221         }
 222         free(s);
 223         return ret;
 224 }
 225
 226 /*
 227  * Filters a proposal string, excluding any algorithm matching the 'filter'
 228  * pattern list.
 229  */
 230 static char *
 231 filter_proposal(char *proposal, const char *filter)
 232 {
 233         Buffer b;
 234         char *orig_prop, *fix_prop;
 235         char *cp, *tmp;
 236
 237         buffer_init(&b);
 238         tmp = orig_prop = xstrdup(proposal);
 239         while ((cp = strsep(&tmp, ",")) != NULL) {
 240                 if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) {
 241                         if (buffer_len(&b) > 0)
 242                                 buffer_append(&b, ",", 1);
 243                         buffer_append(&b, cp, strlen(cp));
 244                 } else
 245                         debug2("Compat: skipping algorithm \"%s\"", cp);
 246         }
 247         buffer_append(&b, "\0", 1);
 248         fix_prop = xstrdup(buffer_ptr(&b));
 249         buffer_free(&b);
 250         free(orig_prop);
 251
 252         return fix_prop;
 253 }
 254
 255 char *
 256 compat_cipher_proposal(char *cipher_prop)
 257 {
 258         if (!(datafellows & SSH_BUG_BIGENDIANAES))
 259                 return cipher_prop;
 260         debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
 261         cipher_prop = filter_proposal(cipher_prop, "aes*");
 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         pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
 275         debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
 276         if (*pkalg_prop == '\0')
 277                 fatal("No supported PK algorithms found");
 278         return pkalg_prop;
 279 }
 280
 281 char *
 282 compat_kex_proposal(char *kex_prop)
 283 {
 284         if (!(datafellows & SSH_BUG_CURVE25519PAD))
 285                 return kex_prop;
 286         debug2("%s: original KEX proposal: %s", __func__, kex_prop);
 287         kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
 288         debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
 289         if (*kex_prop == '\0')
 290                 fatal("No supported key exchange algorithms found");
 291         return kex_prop;
 292 }
 293