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/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single TCP/UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
* Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* @file Control Channel Verification Module
*/
#include "syshead.h"
#include "misc.h"
#include "manage.h"
#include "ssl_verify.h"
#include "ssl_verify_backend.h"
#ifdef USE_OPENSSL
#include "ssl_verify_openssl.h"
#endif
static void
tls_deauthenticate (struct tls_multi *multi)
{
if (multi)
{
int i, j;
for (i = 0; i < TM_SIZE; ++i)
for (j = 0; j < KS_SIZE; ++j)
multi->session[i].key[j].authenticated = false;
}
}
void
set_common_name (struct tls_session *session, const char *common_name)
{
if (session->common_name)
{
free (session->common_name);
session->common_name = NULL;
#ifdef ENABLE_PF
session->common_name_hashval = 0;
#endif
}
if (common_name)
{
session->common_name = string_alloc (common_name, NULL);
#ifdef ENABLE_PF
{
const uint32_t len = (uint32_t) strlen (common_name);
if (len)
session->common_name_hashval = hash_func ((const uint8_t*)common_name, len+1, 0);
else
session->common_name_hashval = 0;
}
#endif
}
}
const char *
tls_common_name (const struct tls_multi *multi, const bool null)
{
const char *ret = NULL;
if (multi)
ret = multi->session[TM_ACTIVE].common_name;
if (ret && strlen (ret))
return ret;
else if (null)
return NULL;
else
return "UNDEF";
}
void
tls_lock_common_name (struct tls_multi *multi)
{
const char *cn = multi->session[TM_ACTIVE].common_name;
if (cn && !multi->locked_cn)
multi->locked_cn = string_alloc (cn, NULL);
}
void
cert_hash_remember (struct tls_session *session, const int error_depth, const unsigned char *sha1_hash)
{
if (error_depth >= 0 && error_depth < MAX_CERT_DEPTH)
{
if (!session->cert_hash_set)
ALLOC_OBJ_CLEAR (session->cert_hash_set, struct cert_hash_set);
if (!session->cert_hash_set->ch[error_depth])
ALLOC_OBJ (session->cert_hash_set->ch[error_depth], struct cert_hash);
{
struct cert_hash *ch = session->cert_hash_set->ch[error_depth];
memcpy (ch->sha1_hash, sha1_hash, SHA_DIGEST_LENGTH);
}
}
}
#if 0
static void
cert_hash_print (const struct cert_hash_set *chs, int msglevel)
{
struct gc_arena gc = gc_new ();
msg (msglevel, "CERT_HASH");
if (chs)
{
int i;
for (i = 0; i < MAX_CERT_DEPTH; ++i)
{
const struct cert_hash *ch = chs->ch[i];
if (ch)
msg (msglevel, "%d:%s", i, format_hex(ch->sha1_hash, SHA_DIGEST_LENGTH, 0, &gc));
}
}
gc_free (&gc);
}
#endif
void
cert_hash_free (struct cert_hash_set *chs)
{
if (chs)
{
int i;
for (i = 0; i < MAX_CERT_DEPTH; ++i)
free (chs->ch[i]);
free (chs);
}
}
static bool
cert_hash_compare (const struct cert_hash_set *chs1, const struct cert_hash_set *chs2)
{
if (chs1 && chs2)
{
int i;
for (i = 0; i < MAX_CERT_DEPTH; ++i)
{
const struct cert_hash *ch1 = chs1->ch[i];
const struct cert_hash *ch2 = chs2->ch[i];
if (!ch1 && !ch2)
continue;
else if (ch1 && ch2 && !memcmp (ch1->sha1_hash, ch2->sha1_hash, SHA_DIGEST_LENGTH))
continue;
else
return false;
}
return true;
}
else if (!chs1 && !chs2)
return true;
else
return false;
}
static struct cert_hash_set *
cert_hash_copy (const struct cert_hash_set *chs)
{
struct cert_hash_set *dest = NULL;
if (chs)
{
int i;
ALLOC_OBJ_CLEAR (dest, struct cert_hash_set);
for (i = 0; i < MAX_CERT_DEPTH; ++i)
{
const struct cert_hash *ch = chs->ch[i];
if (ch)
{
ALLOC_OBJ (dest->ch[i], struct cert_hash);
memcpy (dest->ch[i]->sha1_hash, ch->sha1_hash, SHA_DIGEST_LENGTH);
}
}
}
return dest;
}
void
tls_lock_cert_hash_set (struct tls_multi *multi)
{
const struct cert_hash_set *chs = multi->session[TM_ACTIVE].cert_hash_set;
if (chs && !multi->locked_cert_hash_set)
multi->locked_cert_hash_set = cert_hash_copy (chs);
}
void
verify_final_auth_checks(struct tls_multi *multi, struct tls_session *session)
{
/* While it shouldn't really happen, don't allow the common name to be NULL */
if (!session->common_name)
set_common_name (session, "");
/* Don't allow the CN to change once it's been locked */
if (multi->locked_cn)
{
const char *cn = session->common_name;
if (cn && strcmp (cn, multi->locked_cn))
{
msg (D_TLS_ERRORS, "TLS Auth Error: TLS object CN attempted to change from '%s' to '%s' -- tunnel disabled",
multi->locked_cn,
cn);
/* change the common name back to its original value and disable the tunnel */
set_common_name (session, multi->locked_cn);
tls_deauthenticate (multi);
}
}
/* Don't allow the cert hashes to change once they have been locked */
if (multi->locked_cert_hash_set)
{
const struct cert_hash_set *chs = session->cert_hash_set;
if (chs && !cert_hash_compare (chs, multi->locked_cert_hash_set))
{
msg (D_TLS_ERRORS, "TLS Auth Error: TLS object CN=%s client-provided SSL certs unexpectedly changed during mid-session reauth",
session->common_name);
/* disable the tunnel */
tls_deauthenticate (multi);
}
}
/* verify --client-config-dir based authentication */
if (session->opt->client_config_dir_exclusive)
{
struct key_state *ks = &session->key[KS_PRIMARY]; /* primary key */
struct gc_arena gc = gc_new ();
const char *cn = session->common_name;
const char *path = gen_path (session->opt->client_config_dir_exclusive, cn, &gc);
if (!cn || !strcmp (cn, CCD_DEFAULT) || !test_file (path))
{
ks->authenticated = false;
msg (D_TLS_ERRORS, "TLS Auth Error: --client-config-dir authentication failed for common name '%s' file='%s'",
session->common_name,
path ? path : "UNDEF");
}
gc_free (&gc);
}
}
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