crypto/openssh/compat.c

   1 /* $OpenBSD: compat.c,v 1.120 2022/07/01 03:35:45 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 #include "kex.h"
  40
  41 /* determine bug flags from SSH protocol banner */
  42 void
  43 compat_banner(struct ssh *ssh, const char *version)
  44 {
  45         int i;
  46         static struct {
  47                 char    *pat;
  48                 int     bugs;
  49         } check[] = {
  50                 { "OpenSSH_2.*,"
  51                   "OpenSSH_3.0*,"
  52                   "OpenSSH_3.1*",       SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR|
  53                                         SSH_BUG_SIGTYPE},
  54                 { "OpenSSH_3.*",        SSH_OLD_FORWARD_ADDR|SSH_BUG_SIGTYPE },
  55                 { "Sun_SSH_1.0*",       SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
  56                                         SSH_BUG_SIGTYPE},
  57                 { "OpenSSH_2*,"
  58                   "OpenSSH_3*,"
  59                   "OpenSSH_4*",         SSH_BUG_SIGTYPE },
  60                 { "OpenSSH_5*",         SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT|
  61                                         SSH_BUG_SIGTYPE},
  62                 { "OpenSSH_6.6.1*",     SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  63                 { "OpenSSH_6.5*,"
  64                   "OpenSSH_6.6*",       SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD|
  65                                         SSH_BUG_SIGTYPE},
  66                 { "OpenSSH_7.4*",       SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE|
  67                                         SSH_BUG_SIGTYPE74},
  68                 { "OpenSSH_7.0*,"
  69                   "OpenSSH_7.1*,"
  70                   "OpenSSH_7.2*,"
  71                   "OpenSSH_7.3*,"
  72                   "OpenSSH_7.5*,"
  73                   "OpenSSH_7.6*,"
  74                   "OpenSSH_7.7*",       SSH_NEW_OPENSSH|SSH_BUG_SIGTYPE},
  75                 { "OpenSSH*",           SSH_NEW_OPENSSH },
  76                 { "*MindTerm*",         0 },
  77                 { "3.0.*",              SSH_BUG_DEBUG },
  78                 { "3.0 SecureCRT*",     SSH_OLD_SESSIONID },
  79                 { "1.7 SecureFX*",      SSH_OLD_SESSIONID },
  80                 { "1.2.18*,"
  81                   "1.2.19*,"
  82                   "1.2.20*,"
  83                   "1.2.21*,"
  84                   "1.2.22*",            SSH_BUG_IGNOREMSG },
  85                 { "1.3.2*",             /* F-Secure */
  86                                         SSH_BUG_IGNOREMSG },
  87                 { "Cisco-1.*",          SSH_BUG_DHGEX_LARGE|
  88                                         SSH_BUG_HOSTKEYS },
  89                 { "*SSH Compatible Server*",                    /* Netscreen */
  90                                         SSH_BUG_PASSWORDPAD },
  91                 { "*OSU_0*,"
  92                   "OSU_1.0*,"
  93                   "OSU_1.1*,"
  94                   "OSU_1.2*,"
  95                   "OSU_1.3*,"
  96                   "OSU_1.4*,"
  97                   "OSU_1.5alpha1*,"
  98                   "OSU_1.5alpha2*,"
  99                   "OSU_1.5alpha3*",     SSH_BUG_PASSWORDPAD },
 100                 { "*SSH_Version_Mapper*",
 101                                         SSH_BUG_SCANNER },
 102                 { "PuTTY_Local:*,"      /* dev versions < Sep 2014 */
 103                   "PuTTY-Release-0.5*," /* 0.50-0.57, DH-GEX in >=0.52 */
 104                   "PuTTY_Release_0.5*," /* 0.58-0.59 */
 105                   "PuTTY_Release_0.60*,"
 106                   "PuTTY_Release_0.61*,"
 107                   "PuTTY_Release_0.62*,"
 108                   "PuTTY_Release_0.63*,"
 109                   "PuTTY_Release_0.64*",
 110                                         SSH_OLD_DHGEX },
 111                 { "FuTTY*",             SSH_OLD_DHGEX }, /* Putty Fork */
 112                 { "Probe-*",
 113                                         SSH_BUG_PROBE },
 114                 { "TeraTerm SSH*,"
 115                   "TTSSH/1.5.*,"
 116                   "TTSSH/2.1*,"
 117                   "TTSSH/2.2*,"
 118                   "TTSSH/2.3*,"
 119                   "TTSSH/2.4*,"
 120                   "TTSSH/2.5*,"
 121                   "TTSSH/2.6*,"
 122                   "TTSSH/2.70*,"
 123                   "TTSSH/2.71*,"
 124                   "TTSSH/2.72*",        SSH_BUG_HOSTKEYS },
 125                 { "WinSCP_release_4*,"
 126                   "WinSCP_release_5.0*,"
 127                   "WinSCP_release_5.1,"
 128                   "WinSCP_release_5.1.*,"
 129                   "WinSCP_release_5.5,"
 130                   "WinSCP_release_5.5.*,"
 131                   "WinSCP_release_5.6,"
 132                   "WinSCP_release_5.6.*,"
 133                   "WinSCP_release_5.7,"
 134                   "WinSCP_release_5.7.1,"
 135                   "WinSCP_release_5.7.2,"
 136                   "WinSCP_release_5.7.3,"
 137                   "WinSCP_release_5.7.4",
 138                                         SSH_OLD_DHGEX },
 139                 { "ConfD-*",
 140                                         SSH_BUG_UTF8TTYMODE },
 141                 { "Twisted_*",          0 },
 142                 { "Twisted*",           SSH_BUG_DEBUG },
 143                 { NULL,                 0 }
 144         };
 145
 146         /* process table, return first match */
 147         ssh->compat = 0;
 148         for (i = 0; check[i].pat; i++) {
 149                 if (match_pattern_list(version, check[i].pat, 0) == 1) {
 150                         debug_f("match: %s pat %s compat 0x%08x",
 151                             version, check[i].pat, check[i].bugs);
 152                         ssh->compat = check[i].bugs;
 153                         return;
 154                 }
 155         }
 156         debug_f("no match: %s", version);
 157 }
 158
 159 /* Always returns pointer to allocated memory, caller must free. */
 160 char *
 161 compat_cipher_proposal(struct ssh *ssh, char *cipher_prop)
 162 {
 163         if (!(ssh->compat & SSH_BUG_BIGENDIANAES))
 164                 return xstrdup(cipher_prop);
 165         debug2_f("original cipher proposal: %s", cipher_prop);
 166         if ((cipher_prop = match_filter_denylist(cipher_prop, "aes*")) == NULL)
 167                 fatal("match_filter_denylist failed");
 168         debug2_f("compat cipher proposal: %s", cipher_prop);
 169         if (*cipher_prop == '\0')
 170                 fatal("No supported ciphers found");
 171         return cipher_prop;
 172 }
 173
 174 /* Always returns pointer to allocated memory, caller must free. */
 175 char *
 176 compat_pkalg_proposal(struct ssh *ssh, char *pkalg_prop)
 177 {
 178         if (!(ssh->compat & SSH_BUG_RSASIGMD5))
 179                 return xstrdup(pkalg_prop);
 180         debug2_f("original public key proposal: %s", pkalg_prop);
 181         if ((pkalg_prop = match_filter_denylist(pkalg_prop, "ssh-rsa")) == NULL)
 182                 fatal("match_filter_denylist failed");
 183         debug2_f("compat public key proposal: %s", pkalg_prop);
 184         if (*pkalg_prop == '\0')
 185                 fatal("No supported PK algorithms found");
 186         return pkalg_prop;
 187 }
 188
 189 /* Always returns pointer to allocated memory, caller must free. */
 190 char *
 191 compat_kex_proposal(struct ssh *ssh, char *p)
 192 {
 193         char *cp = NULL;
 194
 195         if ((ssh->compat & (SSH_BUG_CURVE25519PAD|SSH_OLD_DHGEX)) == 0)
 196                 return xstrdup(p);
 197         debug2_f("original KEX proposal: %s", p);
 198         if ((ssh->compat & SSH_BUG_CURVE25519PAD) != 0)
 199                 if ((p = match_filter_denylist(p,
 200                     "curve25519-sha256@libssh.org")) == NULL)
 201                         fatal("match_filter_denylist failed");
 202         if ((ssh->compat & SSH_OLD_DHGEX) != 0) {
 203                 cp = p;
 204                 if ((p = match_filter_denylist(p,
 205                     "diffie-hellman-group-exchange-sha256,"
 206                     "diffie-hellman-group-exchange-sha1")) == NULL)
 207                         fatal("match_filter_denylist failed");
 208                 free(cp);
 209         }
 210         debug2_f("compat KEX proposal: %s", p);
 211         if (*p == '\0')
 212                 fatal("No supported key exchange algorithms found");
 213         return p;
 214 }
 215