compat.c

   1 /* $OpenBSD: compat.c,v 1.126 2023/03/06 12:14:48 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 "packet.h"
  36 #include "compat.h"
  37 #include "log.h"
  38 #include "match.h"
  39
  40 /* determine bug flags from SSH protocol banner */
  41 void
  42 compat_banner(struct ssh *ssh, const char *version)
  43 {
  44         int i;
  45         static struct {
  46                 char    *pat;
  47                 int     bugs;
  48         } check[] = {
  49                 { "OpenSSH_2.*,"
  50                   "OpenSSH_3.0*,"
  51                   "OpenSSH_3.1*",       SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
  52                                         SSH_BUG_SIGTYPE},
  53                 { "OpenSSH_3.*",        SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
  54                 { "Sun_SSH_1.0*",       SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
  55                                         SSH_BUG_SIGTYPE},
  56                 { "OpenSSH_2*,"
  57                   "OpenSSH_3*,"
  58                   "OpenSSH_4*",         SSH_BUG_SIGTYPE },
  59                 { "OpenSSH_5*",         SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
  60                                         SSH_BUG_SIGTYPE},
  61                 { "OpenSSH_6.6.1*",     SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  62                 { "OpenSSH_6.5*,"
  63                   "OpenSSH_6.6*",       SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
  64                                         SSH_BUG_SIGTYPE},
  65                 { "OpenSSH_7.4*",       SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
  66                                         SSH_BUG_SIGTYPE74},
  67                 { "OpenSSH_7.0*,"
  68                   "OpenSSH_7.1*,"
  69                   "OpenSSH_7.2*,"
  70                   "OpenSSH_7.3*,"
  71                   "OpenSSH_7.5*,"
  72                   "OpenSSH_7.6*,"
  73                   "OpenSSH_7.7*",       SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  74                 { "OpenSSH*",           SSH_NEW_OPENSSH },
  75                 { "*MindTerm*",         0 },
  76                 { "3.0.*",              SSH_BUG_DEBUG },
  77                 { "3.0 SecureCRT*",     SSH_OLD_SESSIONID },
  78                 { "1.7 SecureFX*",      SSH_OLD_SESSIONID },
  79                 { "Cisco-1.*",          SSH_BUG_DHGEX_LARGE|
  80                                         SSH_BUG_HOSTKEYS },
  81                 { "*SSH_Version_Mapper*",
  82                                         SSH_BUG_SCANNER },
  83                 { "PuTTY_Local:*,"      /* dev versions < Sep 2014 */
  84                   "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
  85                   "PuTTY_Release_0.5*," /* 0.58-0.59 */
  86                   "PuTTY_Release_0.60*,"
  87                   "PuTTY_Release_0.61*,"
  88                   "PuTTY_Release_0.62*,"
  89                   "PuTTY_Release_0.63*,"
  90                   "PuTTY_Release_0.64*",
  91                                         SSH_OLD_DHGEX },
  92                 { "FuTTY*",             SSH_OLD_DHGEX }, /* Putty Fork */
  93                 { "Probe-*",
  94                                         SSH_BUG_PROBE },
  95                 { "TeraTerm SSH*,"
  96                   "TTSSH/1.5.*,"
  97                   "TTSSH/2.1*,"
  98                   "TTSSH/2.2*,"
  99                   "TTSSH/2.3*,"
 100                   "TTSSH/2.4*,"
 101                   "TTSSH/2.5*,"
 102                   "TTSSH/2.6*,"
 103                   "TTSSH/2.70*,"
 104                   "TTSSH/2.71*,"
 105                   "TTSSH/2.72*",        SSH_BUG_HOSTKEYS },
 106                 { "WinSCP_release_4*,"
 107                   "WinSCP_release_5.0*,"
 108                   "WinSCP_release_5.1,"
 109                   "WinSCP_release_5.1.*,"
 110                   "WinSCP_release_5.5,"
 111                   "WinSCP_release_5.5.*,"
 112                   "WinSCP_release_5.6,"
 113                   "WinSCP_release_5.6.*,"
 114                   "WinSCP_release_5.7,"
 115                   "WinSCP_release_5.7.1,"
 116                   "WinSCP_release_5.7.2,"
 117                   "WinSCP_release_5.7.3,"
 118                   "WinSCP_release_5.7.4",
 119                                         SSH_OLD_DHGEX },
 120                 { "ConfD-*",
 121                                         SSH_BUG_UTF8TTYMODE },
 122                 { "Twisted_*",          0 },
 123                 { "Twisted*",           SSH_BUG_DEBUG },
 124                 { NULL,                 0 }
 125         };
 126
 127         /* process table, return first match */
 128         ssh->compat = 0;
 129         for (i = 0; check[i].pat; i++) {
 130                 if (match_pattern_list(version, check[i].pat, 0) == 1) {
 131                         debug_f("match: %s pat %s compat 0x%08x",
 132                             version, check[i].pat, check[i].bugs);
 133                         ssh->compat = check[i].bugs;
 134                         return;
 135                 }
 136         }
 137         debug_f("no match: %s", version);
 138 }
 139
 140 /* Always returns pointer to allocated memory, caller must free. */
 141 char *
 142 compat_kex_proposal(struct ssh *ssh, const char *p)
 143 {
 144         char *cp = NULL, *cp2 = NULL;
 145
 146         if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
 147                 return xstrdup(p);
 148         debug2_f("original KEX proposal: %s", p);
 149         if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
 150                 if ((cp = match_filter_denylist(p,
 151                     "curve25519-sha256@libssh.org")) == NULL)
 152                         fatal("match_filter_denylist failed");
 153         if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
 154                 if ((cp2 = match_filter_denylist(cp ? cp : p,
 155                     "diffie-hellman-group-exchange-sha256,"
 156                     "diffie-hellman-group-exchange-sha1")) == NULL)
 157                         fatal("match_filter_denylist failed");
 158                 free(cp);
 159                 cp = cp2;
 160         }
 161         if (cp == NULL || *cp == '\0')
 162                 fatal("No supported key exchange algorithms found");
 163         debug2_f("compat KEX proposal: %s", cp);
 164         return cp;
 165 }
 166