/* $OpenBSD: compat.c,v 1.87 2015/01/19 20:20:20 markus Exp $ */
/*
* Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include "xmalloc.h"
#include "buffer.h"
#include "packet.h"
#include "compat.h"
#include "log.h"
#include "match.h"
int compat13 = 0;
int compat20 = 0;
int datafellows = 0;
void
enable_compat20(void)
{
if (compat20)
return;
debug("Enabling compatibility mode for protocol 2.0");
compat20 = 1;
}
void
enable_compat13(void)
{
debug("Enabling compatibility mode for protocol 1.3");
compat13 = 1;
}
/* datafellows bug compatibility */
u_int
compat_datafellows(const char *version)
{
int i;
static struct {
char *pat;
int bugs;
} check[] = {
{ "OpenSSH-2.0*,"
"OpenSSH-2.1*,"
"OpenSSH_2.1*,"
"OpenSSH_2.2*", SSH_OLD_SESSIONID|SSH_BUG_BANNER|
SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.3.0*", SSH_BUG_BANNER|SSH_BUG_BIGENDIANAES|
SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.3.*", SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.5.0p1*,"
"OpenSSH_2.5.1p1*",
SSH_BUG_BIGENDIANAES|SSH_OLD_DHGEX|
SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.5.0*,"
"OpenSSH_2.5.1*,"
"OpenSSH_2.5.2*", SSH_OLD_DHGEX|SSH_BUG_NOREKEY|
SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.5.3*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF|
SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_2.*,"
"OpenSSH_3.0*,"
"OpenSSH_3.1*", SSH_BUG_EXTEOF|SSH_OLD_FORWARD_ADDR},
{ "OpenSSH_3.*", SSH_OLD_FORWARD_ADDR },
{ "Sun_SSH_1.0*", SSH_BUG_NOREKEY|SSH_BUG_EXTEOF},
{ "OpenSSH_4*", 0 },
{ "OpenSSH_5*", SSH_NEW_OPENSSH|SSH_BUG_DYNAMIC_RPORT},
{ "OpenSSH_6.6.1*", SSH_NEW_OPENSSH},
{ "OpenSSH_6.5*,"
"OpenSSH_6.6*", SSH_NEW_OPENSSH|SSH_BUG_CURVE25519PAD},
{ "OpenSSH*", SSH_NEW_OPENSSH },
{ "*MindTerm*", 0 },
{ "2.1.0*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
SSH_BUG_FIRSTKEX },
{ "2.1 *", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
SSH_BUG_RSASIGMD5|SSH_BUG_HBSERVICE|
SSH_BUG_FIRSTKEX },
{ "2.0.13*,"
"2.0.14*,"
"2.0.15*,"
"2.0.16*,"
"2.0.17*,"
"2.0.18*,"
"2.0.19*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
SSH_BUG_PKOK|SSH_BUG_RSASIGMD5|
SSH_BUG_HBSERVICE|SSH_BUG_OPENFAILURE|
SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
{ "2.0.11*,"
"2.0.12*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
SSH_BUG_PKAUTH|SSH_BUG_PKOK|
SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
SSH_BUG_DUMMYCHAN|SSH_BUG_FIRSTKEX },
{ "2.0.*", SSH_BUG_SIGBLOB|SSH_BUG_HMAC|
SSH_OLD_SESSIONID|SSH_BUG_DEBUG|
SSH_BUG_PKSERVICE|SSH_BUG_X11FWD|
SSH_BUG_PKAUTH|SSH_BUG_PKOK|
SSH_BUG_RSASIGMD5|SSH_BUG_OPENFAILURE|
SSH_BUG_DERIVEKEY|SSH_BUG_DUMMYCHAN|
SSH_BUG_FIRSTKEX },
{ "2.2.0*,"
"2.3.0*", SSH_BUG_HMAC|SSH_BUG_DEBUG|
SSH_BUG_RSASIGMD5|SSH_BUG_FIRSTKEX },
{ "2.3.*", SSH_BUG_DEBUG|SSH_BUG_RSASIGMD5|
SSH_BUG_FIRSTKEX },
{ "2.4", SSH_OLD_SESSIONID }, /* Van Dyke */
{ "2.*", SSH_BUG_DEBUG|SSH_BUG_FIRSTKEX|
SSH_BUG_RFWD_ADDR },
{ "3.0.*", SSH_BUG_DEBUG },
{ "3.0 SecureCRT*", SSH_OLD_SESSIONID },
{ "1.7 SecureFX*", SSH_OLD_SESSIONID },
{ "1.2.18*,"
"1.2.19*,"
"1.2.20*,"
"1.2.21*,"
"1.2.22*", SSH_BUG_IGNOREMSG },
{ "1.3.2*", /* F-Secure */
SSH_BUG_IGNOREMSG },
{ "*SSH Compatible Server*", /* Netscreen */
SSH_BUG_PASSWORDPAD },
{ "*OSU_0*,"
"OSU_1.0*,"
"OSU_1.1*,"
"OSU_1.2*,"
"OSU_1.3*,"
"OSU_1.4*,"
"OSU_1.5alpha1*,"
"OSU_1.5alpha2*,"
"OSU_1.5alpha3*", SSH_BUG_PASSWORDPAD },
{ "*SSH_Version_Mapper*",
SSH_BUG_SCANNER },
{ "Probe-*",
SSH_BUG_PROBE },
{ NULL, 0 }
};
/* process table, return first match */
for (i = 0; check[i].pat; i++) {
if (match_pattern_list(version, check[i].pat,
strlen(check[i].pat), 0) == 1) {
debug("match: %s pat %s compat 0x%08x",
version, check[i].pat, check[i].bugs);
datafellows = check[i].bugs; /* XXX for now */
return check[i].bugs;
}
}
debug("no match: %s", version);
return 0;
}
#define SEP ","
int
proto_spec(const char *spec)
{
char *s, *p, *q;
int ret = SSH_PROTO_UNKNOWN;
if (spec == NULL)
return ret;
q = s = strdup(spec);
if (s == NULL)
return ret;
for ((p = strsep(&q, SEP)); p && *p != '\0'; (p = strsep(&q, SEP))) {
switch (atoi(p)) {
case 1:
if (ret == SSH_PROTO_UNKNOWN)
ret |= SSH_PROTO_1_PREFERRED;
ret |= SSH_PROTO_1;
break;
case 2:
ret |= SSH_PROTO_2;
break;
default:
logit("ignoring bad proto spec: '%s'.", p);
break;
}
}
free(s);
return ret;
}
/*
* Filters a proposal string, excluding any algorithm matching the 'filter'
* pattern list.
*/
static char *
filter_proposal(char *proposal, const char *filter)
{
Buffer b;
char *orig_prop, *fix_prop;
char *cp, *tmp;
buffer_init(&b);
tmp = orig_prop = xstrdup(proposal);
while ((cp = strsep(&tmp, ",")) != NULL) {
if (match_pattern_list(cp, filter, strlen(cp), 0) != 1) {
if (buffer_len(&b) > 0)
buffer_append(&b, ",", 1);
buffer_append(&b, cp, strlen(cp));
} else
debug2("Compat: skipping algorithm \"%s\"", cp);
}
buffer_append(&b, "\0", 1);
fix_prop = xstrdup((char *)buffer_ptr(&b));
buffer_free(&b);
free(orig_prop);
return fix_prop;
}
char *
compat_cipher_proposal(char *cipher_prop)
{
if (!(datafellows & SSH_BUG_BIGENDIANAES))
return cipher_prop;
debug2("%s: original cipher proposal: %s", __func__, cipher_prop);
cipher_prop = filter_proposal(cipher_prop, "aes*");
debug2("%s: compat cipher proposal: %s", __func__, cipher_prop);
if (*cipher_prop == '\0')
fatal("No supported ciphers found");
return cipher_prop;
}
char *
compat_pkalg_proposal(char *pkalg_prop)
{
if (!(datafellows & SSH_BUG_RSASIGMD5))
return pkalg_prop;
debug2("%s: original public key proposal: %s", __func__, pkalg_prop);
pkalg_prop = filter_proposal(pkalg_prop, "ssh-rsa");
debug2("%s: compat public key proposal: %s", __func__, pkalg_prop);
if (*pkalg_prop == '\0')
fatal("No supported PK algorithms found");
return pkalg_prop;
}
char *
compat_kex_proposal(char *kex_prop)
{
if (!(datafellows & SSH_BUG_CURVE25519PAD))
return kex_prop;
debug2("%s: original KEX proposal: %s", __func__, kex_prop);
kex_prop = filter_proposal(kex_prop, "curve25519-sha256@libssh.org");
debug2("%s: compat KEX proposal: %s", __func__, kex_prop);
if (*kex_prop == '\0')
fatal("No supported key exchange algorithms found");
return kex_prop;
}