path: root/src/openvpn/ssl_verify.c

/*
 *  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
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#ifdef ENABLE_CRYPTO

#include "misc.h"
#include "manage.h"
#include "otime.h"
#include "base64.h"
#include "ssl_verify.h"
#include "ssl_verify_backend.h"

#ifdef ENABLE_CRYPTO_OPENSSL
#include "ssl_verify_openssl.h"
#endif

/** Maximum length of common name */
#define TLS_USERNAME_LEN 64

/** Legal characters in an X509 name with --compat-names */
#define X509_NAME_CHAR_CLASS   (CC_ALNUM|CC_UNDERBAR|CC_DASH|CC_DOT|CC_AT|CC_SLASH|CC_COLON|CC_EQUAL)

/** Legal characters in a common name with --compat-names */
#define COMMON_NAME_CHAR_CLASS (CC_ALNUM|CC_UNDERBAR|CC_DASH|CC_DOT|CC_AT|CC_SLASH)

static void
string_mod_remap_name (char *str, const unsigned int restrictive_flags)
{
  if (compat_flag (COMPAT_FLAG_QUERY | COMPAT_NAMES)
      && !compat_flag (COMPAT_FLAG_QUERY | COMPAT_NO_NAME_REMAPPING))
    string_mod (str, restrictive_flags, 0, '_');
  else
    string_mod (str, CC_PRINT, CC_CRLF, '_');
}

/*
 * Export the untrusted IP address and port to the environment
 */
static void
setenv_untrusted (struct tls_session *session)
{
  setenv_link_socket_actual (session->opt->es, "untrusted", &session->untrusted_addr, SA_IP_PORT);
}

/*
 * Remove authenticated state from all sessions in the given tunnel
 */
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;
    }
}

/*
 * Set the given session's common_name
 */
static 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)
    {
      /* FIXME: Last alloc will never be freed */
      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
    }
}

/*
 * Retrieve the common name for the given tunnel's active session. If the
 * common name is NULL or empty, return NULL if null is true, or "UNDEF" if
 * null is false.
 */
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";
}

/*
 * Lock the common name for the given tunnel.
 */
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);
}

/*
 * Lock the username for the given tunnel
 */
static bool
tls_lock_username (struct tls_multi *multi, const char *username)
{
  if (multi->locked_username)
    {
      if (!username || strcmp (username, multi->locked_username))
	{
	  msg (D_TLS_ERRORS, "TLS Auth Error: username attempted to change from '%s' to '%s' -- tunnel disabled",
	       multi->locked_username,
	       np(username));

	  /* disable the tunnel */
	  tls_deauthenticate (multi);
	  return false;
	}
    }
  else
    {
      if (username)
	multi->locked_username = string_alloc (username, NULL);
    }
  return true;
}

const char *
tls_username (const struct tls_multi *multi, const bool null)
{
  const char *ret = NULL;
  if (multi)
    ret = multi->locked_username;
  if (ret && strlen (ret))
    return ret;
  else if (null)
    return NULL;
  else
    return "UNDEF";
}

void
cert_hash_remember (struct tls_session *session, const int error_depth,
    const struct buffer *cert_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];
      ASSERT (sizeof (ch->sha256_hash) == BLEN (cert_hash));
      memcpy (ch->sha256_hash, BPTR (cert_hash), sizeof (ch->sha256_hash));
    }
}

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);
    }
}

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->sha256_hash, ch2->sha256_hash,
	      sizeof(ch1->sha256_hash)))
	    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]->sha256_hash, ch->sha256_hash,
		  sizeof(dest->ch[i]->sha256_hash));
	    }
	}
    }
  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);
}

/*
 * Returns the string associated with the given certificate type.
 */
static const char *
print_nsCertType (int type)
{
  switch (type)
    {
    case NS_CERT_CHECK_SERVER:
      return "SERVER";
    case NS_CERT_CHECK_CLIENT:
      return "CLIENT";
    default:
      return "?";
    }
}

/*
 * Verify the peer's certificate fields.
 *
 * @param opt the tls options to verify against
 * @param peer_cert the peer's certificate
 * @param subject the peer's extracted subject name
 * @param subject the peer's extracted common name
 */
static result_t
verify_peer_cert(const struct tls_options *opt, openvpn_x509_cert_t *peer_cert,
    const char *subject, const char *common_name)
{
  /* verify certificate nsCertType */
  if (opt->ns_cert_type != NS_CERT_CHECK_NONE)
    {
      if (SUCCESS == x509_verify_ns_cert_type (peer_cert, opt->ns_cert_type))
	{
	  msg (D_HANDSHAKE, "VERIFY OK: nsCertType=%s",
	       print_nsCertType (opt->ns_cert_type));
	}
      else
	{
	  msg (D_HANDSHAKE, "VERIFY nsCertType ERROR: %s, require nsCertType=%s",
	       subject, print_nsCertType (opt->ns_cert_type));
	  return FAILURE;		/* Reject connection */
	}
    }

  /* verify certificate ku */
  if (opt->remote_cert_ku[0] != 0)
    {
      if (SUCCESS == x509_verify_cert_ku (peer_cert, opt->remote_cert_ku, MAX_PARMS))
	{
	  msg (D_HANDSHAKE, "VERIFY KU OK");
	}
        else
        {
	  msg (D_HANDSHAKE, "VERIFY KU ERROR");
          return FAILURE;		/* Reject connection */
	}
    }

  /* verify certificate eku */
  if (opt->remote_cert_eku != NULL)
    {
      if (SUCCESS == x509_verify_cert_eku (peer_cert, opt->remote_cert_eku))
        {
	  msg (D_HANDSHAKE, "VERIFY EKU OK");
	}
      else
	{
	  msg (D_HANDSHAKE, "VERIFY EKU ERROR");
          return FAILURE;		/* Reject connection */
	}
    }

  /* verify X509 name or username against --verify-x509-[user]name */
  if (opt->verify_x509_type != VERIFY_X509_NONE)
    {
      if ( (opt->verify_x509_type == VERIFY_X509_SUBJECT_DN
            && strcmp (opt->verify_x509_name, subject) == 0)
        || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN
            && strcmp (opt->verify_x509_name, common_name) == 0)
        || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN_PREFIX
            && strncmp (opt->verify_x509_name, common_name,
                        strlen (opt->verify_x509_name)) == 0) )
	msg (D_HANDSHAKE, "VERIFY X509NAME OK: %s", subject);
      else
	{
	  msg (D_HANDSHAKE, "VERIFY X509NAME ERROR: %s, must be %s",
	       subject, opt->verify_x509_name);
	  return FAILURE;		/* Reject connection */
	}
    }

  return SUCCESS;
}

/*
 * Export the subject, common_name, and raw certificate fields to the
 * environment for later verification by scripts and plugins.
 */
static void
verify_cert_set_env(struct env_set *es, openvpn_x509_cert_t *peer_cert, int cert_depth,
    const char *subject, const char *common_name,
    const struct x509_track *x509_track)
{
  char envname[64];
  char *serial = NULL;
  struct gc_arena gc = gc_new ();

  /* Save X509 fields in environment */
  if (x509_track)
    x509_setenv_track (x509_track, es, cert_depth, peer_cert);
  else
    x509_setenv (es, cert_depth, peer_cert);

  /* export subject name string as environmental variable */
  openvpn_snprintf (envname, sizeof(envname), "tls_id_%d", cert_depth);
  setenv_str (es, envname, subject);

#if 0
  /* export common name string as environmental variable */
  openvpn_snprintf (envname, sizeof(envname), "tls_common_name_%d", cert_depth);
  setenv_str (es, envname, common_name);
#endif

  /* export X509 cert fingerprints */
  {
    struct buffer sha1 = x509_get_sha1_fingerprint(peer_cert, &gc);
    struct buffer sha256 = x509_get_sha256_fingerprint(peer_cert, &gc);

    openvpn_snprintf (envname, sizeof(envname), "tls_digest_%d", cert_depth);
    setenv_str (es, envname,
	format_hex_ex(BPTR(&sha1), BLEN(&sha1), 0, 1, ":", &gc));

    openvpn_snprintf (envname, sizeof(envname), "tls_digest_sha256_%d",
	cert_depth);
    setenv_str (es, envname,
	format_hex_ex(BPTR(&sha256), BLEN(&sha256), 0, 1, ":", &gc));
  }

  /* export serial number as environmental variable */
  serial = backend_x509_get_serial(peer_cert, &gc);
  openvpn_snprintf (envname, sizeof(envname), "tls_serial_%d", cert_depth);
  setenv_str (es, envname, serial);

  /* export serial number in hex as environmental variable */
  serial = backend_x509_get_serial_hex(peer_cert, &gc);
  openvpn_snprintf (envname, sizeof(envname), "tls_serial_hex_%d", cert_depth);
  setenv_str (es, envname, serial);

  gc_free(&gc);
}

/*
 * call --tls-verify plug-in(s)
 */
static result_t
verify_cert_call_plugin(const struct plugin_list *plugins, struct env_set *es,
    int cert_depth, openvpn_x509_cert_t *cert, char *subject)
{
  if (plugin_defined (plugins, OPENVPN_PLUGIN_TLS_VERIFY))
    {
      int ret;
      struct argv argv = argv_new ();

      argv_printf (&argv, "%d %s", cert_depth, subject);

      ret = plugin_call_ssl (plugins, OPENVPN_PLUGIN_TLS_VERIFY, &argv, NULL, es, cert_depth, cert);

      argv_reset (&argv);

      if (ret == OPENVPN_PLUGIN_FUNC_SUCCESS)
	{
	  msg (D_HANDSHAKE, "VERIFY PLUGIN OK: depth=%d, %s",
	      cert_depth, subject);
	}
      else
	{
	  msg (D_HANDSHAKE, "VERIFY PLUGIN ERROR: depth=%d, %s",
	      cert_depth, subject);
	  return FAILURE;		/* Reject connection */
	}
    }
  return SUCCESS;
}

static const char *
verify_cert_export_cert(openvpn_x509_cert_t *peercert, const char *tmp_dir, struct gc_arena *gc)
{
  FILE *peercert_file;
  const char *peercert_filename="";

  if(!tmp_dir)
      return NULL;

  /* create tmp file to store peer cert */
  peercert_filename = create_temp_file (tmp_dir, "pcf", gc);

  /* write peer-cert in tmp-file */
  peercert_file = fopen(peercert_filename, "w+");
  if(!peercert_file)
    {
      msg (M_ERR, "Failed to open temporary file : %s", peercert_filename);
      return NULL;
    }

  if (SUCCESS != x509_write_pem(peercert_file, peercert))
      msg (M_ERR, "Error writing PEM file containing certificate");

  fclose(peercert_file);
  return peercert_filename;
}


/*
 * run --tls-verify script
 */
static result_t
verify_cert_call_command(const char *verify_command, struct env_set *es,
    int cert_depth, openvpn_x509_cert_t *cert, char *subject, const char *verify_export_cert)
{
  const char *tmp_file = NULL;
  int ret;
  struct gc_arena gc = gc_new();
  struct argv argv = argv_new ();

  setenv_str (es, "script_type", "tls-verify");

  if (verify_export_cert)
    {
      if ((tmp_file=verify_cert_export_cert(cert, verify_export_cert, &gc)))
       {
         setenv_str(es, "peer_cert", tmp_file);
       }
    }

  argv_parse_cmd (&argv, verify_command);
  argv_printf_cat (&argv, "%d %s", cert_depth, subject);

  argv_msg_prefix (D_TLS_DEBUG, &argv, "TLS: executing verify command");
  ret = openvpn_run_script (&argv, es, 0, "--tls-verify script");

  if (verify_export_cert)
    {
       if (tmp_file)
          platform_unlink(tmp_file);
    }

  gc_free(&gc);
  argv_reset (&argv);

  if (ret)
    {
      msg (D_HANDSHAKE, "VERIFY SCRIPT OK: depth=%d, %s",
	   cert_depth, subject);
      return SUCCESS;
    }

  msg (D_HANDSHAKE, "VERIFY SCRIPT ERROR: depth=%d, %s",
       cert_depth, subject);
  return FAILURE;		/* Reject connection */
}

/*
 * check peer cert against CRL directory
 */
static result_t
verify_check_crl_dir(const char *crl_dir, openvpn_x509_cert_t *cert)
{
  result_t ret = FAILURE;
  char fn[256];
  int fd = -1;
  struct gc_arena gc = gc_new();

  char *serial = backend_x509_get_serial(cert, &gc);

  if (!openvpn_snprintf(fn, sizeof(fn), "%s%c%s", crl_dir, OS_SPECIFIC_DIRSEP, serial))
    {
      msg (D_HANDSHAKE, "VERIFY CRL: filename overflow");
      goto cleanup;
    }
  fd = platform_open (fn, O_RDONLY, 0);
  if (fd >= 0)
    {
      msg (D_HANDSHAKE, "VERIFY CRL: certificate serial number %s is revoked", serial);
      goto cleanup;
    }

  ret = SUCCESS;

cleanup:

  if (fd != -1)
    close(fd);
  gc_free(&gc);
  return ret;
}

result_t
verify_cert(struct tls_session *session, openvpn_x509_cert_t *cert, int cert_depth)
{
  result_t ret = FAILURE;
  char *subject = NULL;
  char common_name[TLS_USERNAME_LEN+1] = {0}; /* null-terminated */
  const struct tls_options *opt;
  struct gc_arena gc = gc_new();

  opt = session->opt;
  ASSERT (opt);

  session->verified = false;

  /* get the X509 name */
  subject = x509_get_subject(cert, &gc);
  if (!subject)
    {
	msg (D_TLS_ERRORS, "VERIFY ERROR: depth=%d, could not extract X509 "
	    "subject string from certificate", cert_depth);
	goto cleanup;
    }

  /* enforce character class restrictions in X509 name */
  string_mod_remap_name (subject, X509_NAME_CHAR_CLASS);
  string_replace_leading (subject, '-', '_');

  /* extract the username (default is CN) */
  if (SUCCESS != backend_x509_get_username (common_name, sizeof(common_name),
      opt->x509_username_field, cert))
    {
      if (!cert_depth)
	{
	  msg (D_TLS_ERRORS, "VERIFY ERROR: could not extract %s from X509 "
	      "subject string ('%s') -- note that the username length is "
	      "limited to %d characters",
	       opt->x509_username_field,
		 subject,
		 TLS_USERNAME_LEN);
	  goto cleanup;
	}
    }

  /* enforce character class restrictions in common name */
  string_mod_remap_name (common_name, COMMON_NAME_CHAR_CLASS);

  /* warn if cert chain is too deep */
  if (cert_depth >= MAX_CERT_DEPTH)
    {
      msg (D_TLS_ERRORS, "TLS Error: Convoluted certificate chain detected with depth [%d] greater than %d", cert_depth, MAX_CERT_DEPTH);
      goto cleanup;			/* Reject connection */
    }

  /* verify level 1 cert, i.e. the CA that signed our leaf cert */
  if (cert_depth == 1 && opt->verify_hash)
    {
      struct buffer sha1_hash = x509_get_sha1_fingerprint(cert, &gc);
      if (memcmp (BPTR (&sha1_hash), opt->verify_hash, BLEN(&sha1_hash)))
      {
	msg (D_TLS_ERRORS, "TLS Error: level-1 certificate hash verification failed");
	goto cleanup;
      }
    }

  /* save common name in session object */
  if (cert_depth == 0)
    set_common_name (session, common_name);

  session->verify_maxlevel = max_int (session->verify_maxlevel, cert_depth);

  /* export certificate values to the environment */
  verify_cert_set_env(opt->es, cert, cert_depth, subject, common_name,
      opt->x509_track);

  /* export current untrusted IP */
  setenv_untrusted (session);

  /* If this is the peer's own certificate, verify it */
  if (cert_depth == 0 && SUCCESS != verify_peer_cert(opt, cert, subject, common_name))
    goto cleanup;

  /* call --tls-verify plug-in(s), if registered */
  if (SUCCESS != verify_cert_call_plugin(opt->plugins, opt->es, cert_depth, cert, subject))
    goto cleanup;

  /* run --tls-verify script */
  if (opt->verify_command && SUCCESS != verify_cert_call_command(opt->verify_command,
      opt->es, cert_depth, cert, subject, opt->verify_export_cert))
    goto cleanup;

  /* check peer cert against CRL */
  if (opt->crl_file)
    {
      if (opt->ssl_flags & SSLF_CRL_VERIFY_DIR)
	{
	  if (SUCCESS != verify_check_crl_dir(opt->crl_file, cert))
	    goto cleanup;
	}
      else
	{
	  if (tls_verify_crl_missing (opt))
	    {
	      msg (D_TLS_ERRORS, "VERIFY ERROR: CRL not loaded");
	      goto cleanup;
	    }
	}
    }

  msg (D_HANDSHAKE, "VERIFY OK: depth=%d, %s", cert_depth, subject);
  session->verified = true;
  ret = SUCCESS;

cleanup:

  if (ret != SUCCESS)
    {
      tls_clear_error(); /* always? */
      session->verified = false; /* double sure? */
    }
  gc_free(&gc);

  return ret;
}

/* ***************************************************************************
 * Functions for the management of deferred authentication when using
 * user/password authentication.
 *************************************************************************** */

#ifdef ENABLE_DEF_AUTH
/* key_state_test_auth_control_file return values,
   NOTE: acf_merge indexing depends on these values */
#define ACF_UNDEFINED 0
#define ACF_SUCCEEDED 1
#define ACF_DISABLED  2
#define ACF_FAILED    3
#endif

#ifdef MANAGEMENT_DEF_AUTH
void
man_def_auth_set_client_reason (struct tls_multi *multi, const char *client_reason)
{
  if (multi->client_reason)
    {
      free (multi->client_reason);
      multi->client_reason = NULL;
    }
  if (client_reason && strlen (client_reason))
    /* FIXME: Last alloc will never be freed */
    multi->client_reason = string_alloc (client_reason, NULL);
}

static inline unsigned int
man_def_auth_test (const struct key_state *ks)
{
  if (management_enable_def_auth (management))
    return ks->mda_status;
  else
    return ACF_DISABLED;
}
#endif

#ifdef PLUGIN_DEF_AUTH

/*
 * auth_control_file functions
 */

void
key_state_rm_auth_control_file (struct key_state *ks)
{
  if (ks && ks->auth_control_file)
    {
      platform_unlink (ks->auth_control_file);
      free (ks->auth_control_file);
      ks->auth_control_file = NULL;
    }
}

static void
key_state_gen_auth_control_file (struct key_state *ks, const struct tls_options *opt)
{
  struct gc_arena gc = gc_new ();
  const char *acf;

  key_state_rm_auth_control_file (ks);
  acf = create_temp_file (opt->tmp_dir, "acf", &gc);
  if (acf) {
    ks->auth_control_file = string_alloc (acf, NULL);
    setenv_str (opt->es, "auth_control_file", ks->auth_control_file);
  } /* FIXME: Should have better error handling? */

  gc_free (&gc);
}

static unsigned int
key_state_test_auth_control_file (struct key_state *ks)
{
  if (ks && ks->auth_control_file)
    {
      unsigned int ret = ks->auth_control_status;
      if (ret == ACF_UNDEFINED)
	{
	  FILE *fp = fopen (ks->auth_control_file, "r");
	  if (fp)
	    {
	      const int c = fgetc (fp);
	      if (c == '1')
		ret = ACF_SUCCEEDED;
	      else if (c == '0')
		ret = ACF_FAILED;
	      fclose (fp);
	      ks->auth_control_status = ret;
	    }
	}
      return ret;
    }
  return ACF_DISABLED;
}

#endif

/*
 * Return current session authentication state.  Return
 * value is TLS_AUTHENTICATION_x.
 */

int
tls_authentication_status (struct tls_multi *multi, const int latency)
{
  bool deferred = false;
  bool success = false;
  bool active = false;

#ifdef ENABLE_DEF_AUTH
  static const unsigned char acf_merge[] =
    {
      ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_UNDEFINED */
      ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_SUCCEEDED */
      ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_DISABLED */
      ACF_FAILED,    /* s1=ACF_UNDEFINED s2=ACF_FAILED */
      ACF_UNDEFINED, /* s1=ACF_SUCCEEDED s2=ACF_UNDEFINED */
      ACF_SUCCEEDED, /* s1=ACF_SUCCEEDED s2=ACF_SUCCEEDED */
      ACF_SUCCEEDED, /* s1=ACF_SUCCEEDED s2=ACF_DISABLED */
      ACF_FAILED,    /* s1=ACF_SUCCEEDED s2=ACF_FAILED */
      ACF_UNDEFINED, /* s1=ACF_DISABLED  s2=ACF_UNDEFINED */
      ACF_SUCCEEDED, /* s1=ACF_DISABLED  s2=ACF_SUCCEEDED */
      ACF_DISABLED,  /* s1=ACF_DISABLED  s2=ACF_DISABLED */
      ACF_FAILED,    /* s1=ACF_DISABLED  s2=ACF_FAILED */
      ACF_FAILED,    /* s1=ACF_FAILED    s2=ACF_UNDEFINED */
      ACF_FAILED,    /* s1=ACF_FAILED    s2=ACF_SUCCEEDED */
      ACF_FAILED,    /* s1=ACF_FAILED    s2=ACF_DISABLED */
      ACF_FAILED     /* s1=ACF_FAILED    s2=ACF_FAILED */
    };
#endif /* ENABLE_DEF_AUTH */

  if (multi)
    {
      int i;

#ifdef ENABLE_DEF_AUTH
      if (latency && multi->tas_last && multi->tas_last + latency >= now)
	return TLS_AUTHENTICATION_UNDEFINED;
      multi->tas_last = now;
#endif /* ENABLE_DEF_AUTH */

      for (i = 0; i < KEY_SCAN_SIZE; ++i)
	{
	  struct key_state *ks = multi->key_scan[i];
	  if (DECRYPT_KEY_ENABLED (multi, ks))
	    {
	      active = true;
	      if (ks->authenticated)
		{
#ifdef ENABLE_DEF_AUTH
		  unsigned int s1 = ACF_DISABLED;
		  unsigned int s2 = ACF_DISABLED;
#ifdef PLUGIN_DEF_AUTH
		  s1 = key_state_test_auth_control_file (ks);
#endif /* PLUGIN_DEF_AUTH */
#ifdef MANAGEMENT_DEF_AUTH
		  s2 = man_def_auth_test (ks);
#endif /* MANAGEMENT_DEF_AUTH */
		  ASSERT (s1 < 4 && s2 < 4);
		  switch (acf_merge[(s1<<2) + s2])
		    {
		    case ACF_SUCCEEDED:
		    case ACF_DISABLED:
		      success = true;
		      ks->auth_deferred = false;
		      break;
		    case ACF_UNDEFINED:
		      if (now < ks->auth_deferred_expire)
			deferred = true;
		      break;
		    case ACF_FAILED:
		      ks->authenticated = false;
		      break;
		    default:
		      ASSERT (0);
		    }
#else /* !ENABLE_DEF_AUTH */
		  success = true;
#endif /* ENABLE_DEF_AUTH */
		}
	    }
	}
    }

#if 0
  dmsg (D_TLS_ERRORS, "TAS: a=%d s=%d d=%d", active, success, deferred);
#endif

  if (success)
    return TLS_AUTHENTICATION_SUCCEEDED;
  else if (!active || deferred)
    return TLS_AUTHENTICATION_DEFERRED;
  else
    return TLS_AUTHENTICATION_FAILED;
}

#ifdef MANAGEMENT_DEF_AUTH
/*
 * For deferred auth, this is where the management interface calls (on server)
 * to indicate auth failure/success.
 */
bool
tls_authenticate_key (struct tls_multi *multi, const unsigned int mda_key_id, const bool auth, const char *client_reason)
{
  bool ret = false;
  if (multi)
    {
      int i;
      man_def_auth_set_client_reason (multi, client_reason);
      for (i = 0; i < KEY_SCAN_SIZE; ++i)
	{
	  struct key_state *ks = multi->key_scan[i];
	  if (ks->mda_key_id == mda_key_id)
	    {
	      ks->mda_status = auth ? ACF_SUCCEEDED : ACF_FAILED;
	      ret = true;
	    }
	}
    }
  return ret;
}
#endif


/* ****************************************************************************
 * Functions to verify username and password
 *
 * Authenticate a client using username/password.
 * Runs on server.
 *
 * If you want to add new authentication methods,
 * this is the place to start.
 *************************************************************************** */

/*
 * Verify the user name and password using a script
 */
static bool
verify_user_pass_script (struct tls_session *session, const struct user_pass *up)
{
  struct gc_arena gc = gc_new ();
  struct argv argv = argv_new ();
  const char *tmp_file = "";
  bool ret = false;

  /* Is username defined? */
  if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen (up->username))
    {
      /* Set environmental variables prior to calling script */
      setenv_str (session->opt->es, "script_type", "user-pass-verify");

      if (session->opt->auth_user_pass_verify_script_via_file)
	{
	  struct status_output *so;

	  tmp_file = create_temp_file (session->opt->tmp_dir, "up", &gc);
          if( tmp_file ) {
	    so = status_open (tmp_file, 0, -1, NULL, STATUS_OUTPUT_WRITE);
	    status_printf (so, "%s", up->username);
	    status_printf (so, "%s", up->password);
	    if (!status_close (so))
	      {
		msg (D_TLS_ERRORS, "TLS Auth Error: could not write username/password to file: %s",
		     tmp_file);
		goto done;
	      }
          } else {
            msg (D_TLS_ERRORS, "TLS Auth Error: could not create write "
                 "username/password to temp file");
          }
	}
      else
	{
	  setenv_str (session->opt->es, "username", up->username);
	  setenv_str (session->opt->es, "password", up->password);
	}

      /* setenv incoming cert common name for script */
      setenv_str (session->opt->es, "common_name", session->common_name);

      /* setenv client real IP address */
      setenv_untrusted (session);

      /* format command line */
      argv_parse_cmd (&argv, session->opt->auth_user_pass_verify_script);
      argv_printf_cat (&argv, "%s", tmp_file);

      /* call command */
      ret = openvpn_run_script (&argv, session->opt->es, 0,
				"--auth-user-pass-verify");

      if (!session->opt->auth_user_pass_verify_script_via_file)
	setenv_del (session->opt->es, "password");
    }
  else
    {
      msg (D_TLS_ERRORS, "TLS Auth Error: peer provided a blank username");
    }

 done:
  if (tmp_file && strlen (tmp_file) > 0)
    platform_unlink (tmp_file);

  argv_reset (&argv);
  gc_free (&gc);
  return ret;
}

/*
 * Verify the username and password using a plugin
 */
static int
verify_user_pass_plugin (struct tls_session *session, const struct user_pass *up, const char *raw_username)
{
  int retval = OPENVPN_PLUGIN_FUNC_ERROR;
#ifdef PLUGIN_DEF_AUTH
  struct key_state *ks = &session->key[KS_PRIMARY]; 	   /* primary key */
#endif

  /* Is username defined? */
  if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen (up->username))
    {
      /* set username/password in private env space */
      setenv_str (session->opt->es, "username", (raw_username ? raw_username : up->username));
      setenv_str (session->opt->es, "password", up->password);

      /* setenv incoming cert common name for script */
      setenv_str (session->opt->es, "common_name", session->common_name);

      /* setenv client real IP address */
      setenv_untrusted (session);

#ifdef PLUGIN_DEF_AUTH
      /* generate filename for deferred auth control file */
      key_state_gen_auth_control_file (ks, session->opt);
#endif

      /* call command */
      retval = plugin_call (session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY, NULL, NULL, session->opt->es);

#ifdef PLUGIN_DEF_AUTH
      /* purge auth control filename (and file itself) for non-deferred returns */
      if (retval != OPENVPN_PLUGIN_FUNC_DEFERRED)
	key_state_rm_auth_control_file (ks);
#endif

      setenv_del (session->opt->es, "password");
      if (raw_username)
        setenv_str (session->opt->es, "username", up->username);
    }
  else
    {
      msg (D_TLS_ERRORS, "TLS Auth Error (verify_user_pass_plugin): peer provided a blank username");
    }

  return retval;
}


#ifdef MANAGEMENT_DEF_AUTH
/*
 * MANAGEMENT_DEF_AUTH internal ssl_verify.c status codes
 */
#define KMDA_ERROR   0
#define KMDA_SUCCESS 1
#define KMDA_UNDEF   2
#define KMDA_DEF     3

static int
verify_user_pass_management (struct tls_session *session, const struct user_pass *up, const char *raw_username)
{
  int retval = KMDA_ERROR;
  struct key_state *ks = &session->key[KS_PRIMARY]; 	   /* primary key */

  /* Is username defined? */
  if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen (up->username))
    {
      /* set username/password in private env space */
      setenv_str (session->opt->es, "username", (raw_username ? raw_username : up->username));
      setenv_str (session->opt->es, "password", up->password);

      /* setenv incoming cert common name for script */
      setenv_str (session->opt->es, "common_name", session->common_name);

      /* setenv client real IP address */
      setenv_untrusted (session);

      if (management)
	management_notify_client_needing_auth (management, ks->mda_key_id, session->opt->mda_context, session->opt->es);

      setenv_del (session->opt->es, "password");
      if (raw_username)
        setenv_str (session->opt->es, "username", up->username);

      retval = KMDA_SUCCESS;
    }
  else
    {
      msg (D_TLS_ERRORS, "TLS Auth Error (verify_user_pass_management): peer provided a blank username");
    }

  return retval;
}
#endif

/*
 * Main username/password verification entry point
 */
void
verify_user_pass(struct user_pass *up, struct tls_multi *multi,
    struct tls_session *session)
{
  int s1 = OPENVPN_PLUGIN_FUNC_SUCCESS;
  bool s2 = true;
  struct key_state *ks = &session->key[KS_PRIMARY]; 	   /* primary key */

  struct gc_arena gc = gc_new ();
  char *raw_username = NULL;

#ifdef MANAGEMENT_DEF_AUTH
  int man_def_auth = KMDA_UNDEF;

  if (management_enable_def_auth (management))
    man_def_auth = KMDA_DEF;
#endif

  /*
   * Preserve the raw username before string_mod remapping, for plugins
   * and management clients when in --compat-names mode
   */
  if (compat_flag (COMPAT_FLAG_QUERY | COMPAT_NAMES))
    {
      ALLOC_ARRAY_CLEAR_GC (raw_username, char, USER_PASS_LEN, &gc);
      strcpy (raw_username, up->username);
      string_mod (raw_username, CC_PRINT, CC_CRLF, '_');
    }

  /* enforce character class restrictions in username/password */
  string_mod_remap_name (up->username, COMMON_NAME_CHAR_CLASS);
  string_mod (up->password, CC_PRINT, CC_CRLF, '_');

  /* If server is configured with --auth-gen-token and we have an
   * authentication token for this client, this authentication
   * round will be done internally using the token instead of
   * calling any external authentication modules.
   */
  if (session->opt->auth_token_generate && multi->auth_token_sent
      && NULL != multi->auth_token)
    {
      unsigned int ssl_flags = session->opt->ssl_flags;

      /* Ensure that the username has not changed */
      if (!tls_lock_username(multi, up->username))
        {
          ks->authenticated = false;
          goto done;
        }

      /* If auth-token lifetime has been enabled,
       * ensure the token has not expired
       */
      if (session->opt->auth_token_lifetime > 0
          && (multi->auth_token_tstamp + session->opt->auth_token_lifetime) < now)
        {
          msg (D_HANDSHAKE, "Auth-token for client expired\n");
          ks->authenticated = false;
          goto done;
        }

      /* The core authentication of the token itself */
      if (memcmp_constant_time(multi->auth_token, up->password,
                 strlen(multi->auth_token)) != 0)
        {
          memset (multi->auth_token, 0, AUTH_TOKEN_SIZE);
          free (multi->auth_token);
          multi->auth_token = NULL;
          multi->auth_token_sent = false;
          ks->authenticated = false;
          tls_deauthenticate (multi);

          msg (D_TLS_ERRORS, "TLS Auth Error: Auth-token verification "
               "failed for username '%s' %s", up->username,
               (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
        }
      else
        {
          ks->authenticated = true;

          if (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME)
            set_common_name (session, up->username);
          msg (D_HANDSHAKE, "TLS: Username/auth-token authentication "
               "succeeded for username '%s' %s",
               up->username,
               (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
        }
      goto done;
    }

  /* call plugin(s) and/or script */
#ifdef MANAGEMENT_DEF_AUTH
  if (man_def_auth == KMDA_DEF)
    man_def_auth = verify_user_pass_management (session, up, raw_username);
#endif
  if (plugin_defined (session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY))
    s1 = verify_user_pass_plugin (session, up, raw_username);
  if (session->opt->auth_user_pass_verify_script)
    s2 = verify_user_pass_script (session, up);

  /* check sizing of username if it will become our common name */
  if ((session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) && strlen (up->username) > TLS_USERNAME_LEN)
    {
      msg (D_TLS_ERRORS, "TLS Auth Error: --username-as-common name specified and username is longer than the maximum permitted Common Name length of %d characters", TLS_USERNAME_LEN);
      s1 = OPENVPN_PLUGIN_FUNC_ERROR;
    }

  /* auth succeeded? */
  if ((s1 == OPENVPN_PLUGIN_FUNC_SUCCESS
#ifdef PLUGIN_DEF_AUTH
       || s1 == OPENVPN_PLUGIN_FUNC_DEFERRED
#endif
       ) && s2
#ifdef MANAGEMENT_DEF_AUTH
       && man_def_auth != KMDA_ERROR
#endif
      && tls_lock_username (multi, up->username))
    {
      ks->authenticated = true;
#ifdef PLUGIN_DEF_AUTH
      if (s1 == OPENVPN_PLUGIN_FUNC_DEFERRED)
	ks->auth_deferred = true;
#endif
#ifdef MANAGEMENT_DEF_AUTH
      if (man_def_auth != KMDA_UNDEF)
	ks->auth_deferred = true;
#endif

      if ((session->opt->auth_token_generate) && (NULL == multi->auth_token))
	{
	  /* Server is configured with --auth-gen-token but no token has yet
	   * been generated for this client.  Generate one and save it.
	   */
	  uint8_t tok[AUTH_TOKEN_SIZE];

	  if (!rand_bytes(tok, AUTH_TOKEN_SIZE))
	    {
	      msg( M_FATAL, "Failed to get enough randomness for "
                   "authentication token");
	    }

	  /* The token should be longer than the input when
           * being base64 encoded
           */
	  if( openvpn_base64_encode(tok, AUTH_TOKEN_SIZE,
                                    &multi->auth_token) < AUTH_TOKEN_SIZE)
	    {
	      msg(D_TLS_ERRORS, "BASE64 encoding of token failed. "
                  "No auth-token will be activated now");
	      if (multi->auth_token)
		{
		  memset (multi->auth_token, 0, AUTH_TOKEN_SIZE);
		  free (multi->auth_token);
		  multi->auth_token = NULL;
		}
	    }
	  else
	    {
	      multi->auth_token_tstamp = now;
	      dmsg (D_SHOW_KEYS, "Generated token for client: %s",
                    multi->auth_token);
	    }
	}

      if ((session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME))
	set_common_name (session, up->username);
#ifdef ENABLE_DEF_AUTH
      msg (D_HANDSHAKE, "TLS: Username/Password authentication %s for username '%s' %s",
	   ks->auth_deferred ? "deferred" : "succeeded",
	   up->username,
	   (session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
#else
      msg (D_HANDSHAKE, "TLS: Username/Password authentication %s for username '%s' %s",
	   "succeeded",
	   up->username,
	   (session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
#endif
    }
  else
    {
      msg (D_TLS_ERRORS, "TLS Auth Error: Auth Username/Password verification failed for peer");
    }

 done:
  gc_free (&gc);
}

void
verify_final_auth_checks(struct tls_multi *multi, struct tls_session *session)
{
  struct key_state *ks = &session->key[KS_PRIMARY]; 	   /* primary key */

  /* 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 (ks->authenticated && 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 (ks->authenticated && 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 (ks->authenticated && session->opt->client_config_dir_exclusive)
    {
      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);
    }
}
#endif /* ENABLE_CRYPTO */