path: root/lib/ext_signature.c

/*
 * Copyright (C) 2002, 2003, 2004, 2005, 2009, 2010 Free Software
 * Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA
 *
 */

/* This file contains the code the Certificate Type TLS extension.
 * This extension is currently gnutls specific.
 */

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_num.h"
#include <ext_signature.h>
#include <gnutls_state.h>
#include <gnutls_num.h>
#include <gnutls_algorithms.h>

static int _gnutls_signature_algorithm_recv_params (gnutls_session_t session,
						    const opaque * data,
						    size_t data_size);
static int _gnutls_signature_algorithm_send_params (gnutls_session_t session,
						    opaque * data, size_t);
static void signature_algorithms_deinit_data (extension_priv_data_t priv);
static int signature_algorithms_pack (extension_priv_data_t epriv,
				      gnutls_buffer_st * ps);
static int signature_algorithms_unpack (gnutls_buffer_st * ps,
					extension_priv_data_t * _priv);

extension_entry_st ext_mod_sig = {
  .name = "SIGNATURE ALGORITHMS",
  .type = GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS,
  .parse_type = GNUTLS_EXT_TLS,

  .recv_func = _gnutls_signature_algorithm_recv_params,
  .send_func = _gnutls_signature_algorithm_send_params,
  .pack_func = signature_algorithms_pack,
  .unpack_func = signature_algorithms_unpack,
  .deinit_func = signature_algorithms_deinit_data,
};

typedef struct
{
  /* TLS 1.2 signature algorithms */
  gnutls_sign_algorithm_t sign_algorithms[MAX_SIGNATURE_ALGORITHMS];
  uint16_t sign_algorithms_size;
} sig_ext_st;

/* generates a SignatureAndHashAlgorithm structure with length as prefix
 * by using the setup priorities.
 */
int
_gnutls_sign_algorithm_write_params (gnutls_session_t session, opaque * data,
				     size_t max_data_size)
{
  opaque *p = data;
  int len, i, j;
  sign_algorithm_st aid;

  len = session->internals.priorities.sign_algo.algorithms * 2;
  if (max_data_size < len + 2)
    {
      gnutls_assert ();
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }

  _gnutls_write_uint16 (len, p);
  p += 2;

  for (i = j = 0; i < len; i += 2, j++)
    {
      aid =
	_gnutls_sign_to_tls_aid (session->internals.priorities.
				 sign_algo.priority[j]);
      *p = aid.hash_algorithm;
      p++;
      *p = aid.sign_algorithm;
      p++;

    }
  return len + 2;
}


/* Parses the Signature Algorithm structure and stores data into
 * session->security_parameters.extensions.
 */
int
_gnutls_sign_algorithm_parse_data (gnutls_session_t session,
				   const opaque * data, size_t data_size)
{
  int sig, i;
  sig_ext_st *priv;
  extension_priv_data_t epriv;

  priv = gnutls_calloc (1, sizeof (*priv));
  if (priv == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  for (i = 0; i < data_size; i += 2)
    {
      sign_algorithm_st aid;

      aid.hash_algorithm = data[i];
      aid.sign_algorithm = data[i + 1];

      sig = _gnutls_tls_aid_to_sign (&aid);
      if (sig != GNUTLS_SIGN_UNKNOWN)
	{
	  priv->sign_algorithms[priv->sign_algorithms_size++] = sig;
	  if (priv->sign_algorithms_size == MAX_SIGNATURE_ALGORITHMS)
	    break;
	}
    }

  epriv.ptr = priv;
  _gnutls_ext_set_session_data (session,
				GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS, epriv);

  return 0;
}

/*
 * In case of a server: if a SIGNATURE_ALGORITHMS extension type is
 * received then it stores into the session security parameters the
 * new value.
 *
 * In case of a client: If a signature_algorithms have been specified
 * then it is an error;
 */

static int
_gnutls_signature_algorithm_recv_params (gnutls_session_t session,
					 const opaque * data,
					 size_t _data_size)
{
  ssize_t data_size = _data_size;
  int ret;

  if (session->security_parameters.entity == GNUTLS_CLIENT)
    {
      /* nothing for now */
      gnutls_assert ();
      /* Although TLS 1.2 mandates that we must not accept reply
       * to this message, there are good reasons to just ignore it. Check
       * http://www.ietf.org/mail-archive/web/tls/current/msg03880.html
       */
      /* return GNUTLS_E_UNEXPECTED_PACKET; */
    }
  else
    {
      /* SERVER SIDE - we must check if the sent cert type is the right one
       */
      if (data_size > 2)
	{
	  uint16_t len;

	  DECR_LEN (data_size, 2);
	  len = _gnutls_read_uint16 (data);
	  DECR_LEN (data_size, len);

	  ret = _gnutls_sign_algorithm_parse_data (session, data + 2, len);
	  if (ret < 0)
	    {
	      gnutls_assert ();
	      return ret;
	    }
	}
    }

  return 0;
}

/* returns data_size or a negative number on failure
 */
static int
_gnutls_signature_algorithm_send_params (gnutls_session_t session,
					 opaque * data, size_t data_size)
{
  int ret;
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);

  /* this function sends the client extension data */
  if (session->security_parameters.entity == GNUTLS_CLIENT
      && _gnutls_version_has_selectable_sighash (ver))
    {
      if (session->internals.priorities.sign_algo.algorithms > 0)
	{
	  ret =
	    _gnutls_sign_algorithm_write_params (session, data, data_size);
	  if (ret < 0)
	    {
	      gnutls_assert ();
	      return ret;
	    }
	  return ret;
	}
    }

  /* if we are here it means we don't send the extension */
  return 0;
}

/* Returns a requested by the peer signature algorithm that
 * matches the given public key algorithm. Index can be increased
 * to return the second choice etc.
 */
gnutls_sign_algorithm_t
_gnutls_session_get_sign_algo (gnutls_session_t session,
			       gnutls_pk_algorithm_t pk,
			       gnutls_digest_algorithm_t * hash)
{
  unsigned i;
  int ret;
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);
  sig_ext_st *priv;
  extension_priv_data_t epriv;

  ret =
    _gnutls_ext_get_session_data (session,
				  GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS,
				  &epriv);
  priv = epriv.ptr;

  if (ret < 0 || !_gnutls_version_has_selectable_sighash (ver)
      || priv->sign_algorithms_size == 0)
    /* none set, allow all */
    {
      *hash = GNUTLS_DIG_SHA1;
      return _gnutls_x509_pk_to_sign (pk, *hash);
    }

  for (i = 0; i < priv->sign_algorithms_size; i++)
    {
      if (_gnutls_sign_get_pk_algorithm (priv->sign_algorithms[i]) == pk)
	{
	  *hash = _gnutls_sign_get_hash_algorithm (priv->sign_algorithms[i]);
	  return priv->sign_algorithms[i];
	}
    }

  return GNUTLS_SIGN_UNKNOWN;
}


/* Check if the given signature algorithm is accepted by
 * the peer. Returns 0 on success or a negative value
 * on error.
 */
int
_gnutls_session_sign_algo_requested (gnutls_session_t session,
				     gnutls_sign_algorithm_t sig)
{
  unsigned i;
  int ret, hash;
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);
  sig_ext_st *priv;
  extension_priv_data_t epriv;

  if (!_gnutls_version_has_selectable_sighash (ver))
    {
      return 0;
    }

  ret =
    _gnutls_ext_get_session_data (session,
				  GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS,
				  &epriv);
  if (ret < 0)
    {
      gnutls_assert ();
      /* extension not received allow SHA1 and SHA256 */
      hash = _gnutls_sign_get_hash_algorithm (sig);
      if (hash == GNUTLS_DIG_SHA1 || hash == GNUTLS_DIG_SHA256)
	return 0;
      else
	return ret;
    }
  priv = epriv.ptr;

  if (priv->sign_algorithms_size == 0)
    /* none set, allow all */
    {
      return 0;
    }

  for (i = 0; i < priv->sign_algorithms_size; i++)
    {
      if (priv->sign_algorithms[i] == sig)
	{
	  return 0;		/* ok */
	}
    }

  return GNUTLS_E_UNSUPPORTED_SIGNATURE_ALGORITHM;
}

/* Check if the given signature algorithm is supported.
 * This means that it is enabled by the priority functions,
 * and in case of a server a matching certificate exists.
 */
int
_gnutls_session_sign_algo_enabled (gnutls_session_t session,
				   gnutls_sign_algorithm_t sig)
{
  unsigned i;
  int ret;
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);
  sig_ext_st *priv;
  extension_priv_data_t epriv;

  ret =
    _gnutls_ext_get_session_data (session,
				  GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS,
				  &epriv);
  if (ret < 0)
    {
      gnutls_assert ();
      return 0;
    }
  priv = epriv.ptr;

  if (!_gnutls_version_has_selectable_sighash (ver)
      || priv->sign_algorithms_size == 0)
    /* none set, allow all */
    {
      return 0;
    }

  for (i = 0; i < session->internals.priorities.sign_algo.algorithms; i++)
    {
      if (session->internals.priorities.sign_algo.priority[i] == sig)
	{
	  return 0;		/* ok */
	}
    }

  return GNUTLS_E_UNSUPPORTED_SIGNATURE_ALGORITHM;
}

static void
signature_algorithms_deinit_data (extension_priv_data_t priv)
{
  gnutls_free (priv.ptr);
}

static int
signature_algorithms_pack (extension_priv_data_t epriv, gnutls_buffer_st * ps)
{
  sig_ext_st *priv = epriv.ptr;
  int ret, i;

  BUFFER_APPEND_NUM (ps, priv->sign_algorithms_size);
  for (i = 0; i < priv->sign_algorithms_size; i++)
    {
      BUFFER_APPEND_NUM (ps, priv->sign_algorithms[i]);
    }
  return 0;
}

static int
signature_algorithms_unpack (gnutls_buffer_st * ps,
			     extension_priv_data_t * _priv)
{
  sig_ext_st *priv;
  int i, ret;
  extension_priv_data_t epriv;

  priv = gnutls_calloc (1, sizeof (*priv));
  if (priv == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  BUFFER_POP_NUM (ps, priv->sign_algorithms_size);
  for (i = 0; i < priv->sign_algorithms_size; i++)
    {
      BUFFER_POP_NUM (ps, priv->sign_algorithms[i]);
    }

  epriv.ptr = priv;
  *_priv = epriv;

  return 0;

error:
  gnutls_free (priv);
  return ret;
}



/**
 * gnutls_sign_algorithm_get_requested:
 * @session: is a #gnutls_session_t structure.
 * @indx: is an index of the signature algorithm to return
 * @algo: the returned certificate type will be stored there
 *
 * Returns the signature algorithm specified by index that was
 * requested by the peer. If the specified index has no data available
 * this function returns %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE.  If
 * the negotiated TLS version does not support signature algorithms
 * then %GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE will be returned even
 * for the first index.  The first index is 0.
 *
 * This function is useful in the certificate callback functions
 * to assist in selecting the correct certificate.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise
 *   an error code is returned.
 *
 * Since: 2.10.0
 **/
int
gnutls_sign_algorithm_get_requested (gnutls_session_t session,
				     size_t indx,
				     gnutls_sign_algorithm_t * algo)
{
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);
  sig_ext_st *priv;
  extension_priv_data_t epriv;
  int ret;

  ret =
    _gnutls_ext_get_session_data (session,
				  GNUTLS_EXTENSION_SIGNATURE_ALGORITHMS,
				  &epriv);
  if (ret < 0)
    {
      gnutls_assert ();
      return ret;
    }
  priv = epriv.ptr;

  if (!_gnutls_version_has_selectable_sighash (ver)
      || priv->sign_algorithms_size == 0)
    {
      return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
    }

  if (indx < priv->sign_algorithms_size)
    {
      *algo = priv->sign_algorithms[indx];
      return 0;
    }
  else
    return GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE;
}