/*

 * Copyright (C) 2005-2012 Free Software Foundation, Inc.

 * Copyright (C) 2017 Red Hat, 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 program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

/* This file contains the PSK Diffie-Hellman key exchange part of the

 * PSK authentication.  The functions here are used in the handshake.

 */

#include "gnutls_int.h"

#ifdef ENABLE_PSK

/* Contains PSK code for DHE and ECDHE

 */

#include "auth.h"

#include "errors.h"

#include "dh.h"

#include "auth/psk.h"

#include "num.h"

#include "mpi.h"

#include "state.h"

#include "auth/dh_common.h"

#include "auth/ecdhe.h"

#include "datum.h"

#include "auth/psk_passwd.h"

static int proc_ecdhe_psk_server_kx(gnutls_session_t session, uint8_t *data,

            size_t data_size);

static int gen_dhe_psk_server_kx(gnutls_session_t, gnutls_buffer_st *);

static int gen_dhe_psk_client_kx(gnutls_session_t, gnutls_buffer_st *);

static int gen_ecdhe_psk_client_kx(gnutls_session_t, gnutls_buffer_st *);

static int proc_ecdhe_psk_client_kx(gnutls_session_t, uint8_t *, size_t);

static int proc_dhe_psk_server_kx(gnutls_session_t, uint8_t *, size_t);

static int gen_ecdhe_psk_server_kx(gnutls_session_t session,

           gnutls_buffer_st *data);

static int proc_dhe_psk_client_kx(gnutls_session_t session, uint8_t *data,

          size_t data_size);

#ifdef ENABLE_DHE

const mod_auth_st dhe_psk_auth_struct = { "DHE PSK",

            NULL,

            NULL,

            gen_dhe_psk_server_kx,

            gen_dhe_psk_client_kx,

            NULL,

            NULL,

            NULL,

            NULL, /* certificate */

            proc_dhe_psk_server_kx,

            proc_dhe_psk_client_kx,

            NULL,

            NULL };

#endif

#ifdef ENABLE_ECDHE

const mod_auth_st ecdhe_psk_auth_struct = { "ECDHE PSK",

              NULL,

              NULL,

              gen_ecdhe_psk_server_kx,

              gen_ecdhe_psk_client_kx,

              NULL,

              NULL,

              NULL,

              NULL, /* certificate */

              proc_ecdhe_psk_server_kx,

              proc_ecdhe_psk_client_kx,

              NULL,

              NULL };

#endif

static int gen_ecdhe_psk_client_kx(gnutls_session_t session,

           gnutls_buffer_st *data)

{

  int ret, free;

  gnutls_psk_client_credentials_t cred;

  gnutls_datum_t username, key;

  unsigned init_pos = data->length;

  cred = (gnutls_psk_client_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL)

    return gnutls_assert_val(GNUTLS_E_INSUFFICIENT_CREDENTIALS);

  ret = _gnutls_find_psk_key(session, cred, &username, &key, NULL, &free);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_buffer_append_data_prefix16(data, username.data,

              username.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  /* The PSK key is set in there */

  ret = _gnutls_gen_ecdh_common_client_kx_int(session, data, &key);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = data->length - init_pos;

cleanup:

  if (free) {

    _gnutls_free_datum(&username);

    _gnutls_free_key_datum(&key);

  }

  return ret;

}

static int gen_dhe_psk_client_kx(gnutls_session_t session,

         gnutls_buffer_st *data)

{

  int ret, free;

  gnutls_psk_client_credentials_t cred;

  gnutls_datum_t username, key;

  unsigned init_pos = data->length;

  cred = (gnutls_psk_client_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL)

    return gnutls_assert_val(GNUTLS_E_INSUFFICIENT_CREDENTIALS);

  ret = _gnutls_find_psk_key(session, cred, &username, &key, NULL, &free);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_buffer_append_data_prefix16(data, username.data,

              username.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  /* The PSK key is set in there */

  ret = _gnutls_gen_dh_common_client_kx_int(session, data, &key);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = data->length - init_pos;

cleanup:

  if (free) {

    _gnutls_free_datum(&username);

    _gnutls_free_key_datum(&key);

  }

  return ret;

}

static int gen_dhe_psk_server_kx(gnutls_session_t session,

         gnutls_buffer_st *data)

{

  int ret;

  gnutls_psk_server_credentials_t cred;

  gnutls_datum_t hint = { NULL, 0 };

  cred = (gnutls_psk_server_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL) {

    gnutls_assert();

    return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

  }

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  ret = _gnutls_figure_dh_params(session, cred->dh_params,

               cred->params_func, cred->dh_sec_param);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  if (cred->hint) {

    hint.data = (uint8_t *)cred->hint;

    hint.size = strlen(cred->hint);

  }

  ret = _gnutls_buffer_append_data_prefix16(data, hint.data, hint.size);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_dh_common_print_server_kx(session, data);

  if (ret < 0)

    gnutls_assert();

  return ret;

}

static int gen_ecdhe_psk_server_kx(gnutls_session_t session,

           gnutls_buffer_st *data)

{

  int ret;

  gnutls_psk_server_credentials_t cred;

  gnutls_datum_t hint = { NULL, 0 };

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  cred = (gnutls_psk_server_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL) {

    gnutls_assert();

    return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

  }

  if (cred->hint) {

    hint.data = (uint8_t *)cred->hint;

    hint.size = strlen(cred->hint);

  }

  ret = _gnutls_buffer_append_data_prefix16(data, hint.data, hint.size);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_ecdh_common_print_server_kx(session, data,

              get_group(session));

  if (ret < 0)

    gnutls_assert();

  return ret;

}

static int proc_dhe_psk_client_kx(gnutls_session_t session, uint8_t *data,

          size_t data_size)

{

  int ret;

  gnutls_datum_t psk_key;

  gnutls_psk_server_credentials_t cred;

  psk_auth_info_t info;

  gnutls_datum_t username;

  cred = (gnutls_psk_server_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL) {

    gnutls_assert();

    return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

  }

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  DECR_LEN(data_size, 2);

  username.size = _gnutls_read_uint16(&data[0]);

  DECR_LEN(data_size, username.size);

  username.data = &data[2];

  /* copy the username to the auth info structures

   */

  info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

  if (info == NULL) {

    gnutls_assert();

    return GNUTLS_E_INTERNAL_ERROR;

  }

  if (username.size > MAX_USERNAME_SIZE) {

    gnutls_assert();

    return GNUTLS_E_ILLEGAL_SRP_USERNAME;

  }

  ret = _gnutls_copy_psk_username(info, username);

  if (ret < 0)

    return gnutls_assert_val(ret);

  /* Adjust the data */

  data += username.size + 2;

  ret = _gnutls_psk_pwd_find_entry(session, info->username,

           info->username_len, &psk_key, NULL);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_proc_dh_common_client_kx(session, data, data_size,

                 &psk_key);

  _gnutls_free_key_datum(&psk_key);

  return ret;

}

static int proc_ecdhe_psk_client_kx(gnutls_session_t session, uint8_t *data,

            size_t data_size)

{

  int ret;

  gnutls_psk_server_credentials_t cred;

  gnutls_datum_t psk_key;

  psk_auth_info_t info;

  gnutls_datum_t username;

  cred = (gnutls_psk_server_credentials_t)_gnutls_get_cred(

    session, GNUTLS_CRD_PSK);

  if (cred == NULL) {

    gnutls_assert();

    return GNUTLS_E_INSUFFICIENT_CREDENTIALS;

  }

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  DECR_LEN(data_size, 2);

  username.size = _gnutls_read_uint16(&data[0]);

  DECR_LEN(data_size, username.size);

  username.data = &data[2];

  /* copy the username to the auth info structures

   */

  info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

  if (info == NULL) {

    gnutls_assert();

    return GNUTLS_E_INTERNAL_ERROR;

  }

  if (username.size > MAX_USERNAME_SIZE) {

    gnutls_assert();

    return GNUTLS_E_ILLEGAL_SRP_USERNAME;

  }

  ret = _gnutls_copy_psk_username(info, username);

  if (ret < 0)

    return gnutls_assert_val(ret);

  /* Adjust the data */

  data += username.size + 2;

  /* should never fail. It will always return a key even if it is

   * a random one */

  ret = _gnutls_psk_pwd_find_entry(session, info->username,

           info->username_len, &psk_key, NULL);

  if (ret < 0)

    return gnutls_assert_val(ret);

  ret = _gnutls_proc_ecdh_common_client_kx(session, data, data_size,

             get_group(session), &psk_key);

  _gnutls_free_key_datum(&psk_key);

  return ret;

}

static int proc_dhe_psk_server_kx(gnutls_session_t session, uint8_t *data,

          size_t data_size)

{

  int ret;

  psk_auth_info_t info;

  gnutls_datum_t hint;

  /* set auth_info */

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  DECR_LEN(data_size, 2);

  hint.size = _gnutls_read_uint16(&data[0]);

  hint.data = &data[2];

  DECR_LEN(data_size, hint.size);

  data += 2 + hint.size;

  ret = _gnutls_proc_dh_common_server_kx(session, data, data_size);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

  if (info == NULL)

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  if (hint.size > MAX_USERNAME_SIZE)

    return gnutls_assert_val(GNUTLS_E_ILLEGAL_SRP_USERNAME);

  ret = _gnutls_copy_psk_hint(info, hint);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  return 0;

}

static int proc_ecdhe_psk_server_kx(gnutls_session_t session, uint8_t *data,

            size_t data_size)

{

  int ret;

  psk_auth_info_t info;

  gnutls_datum_t hint;

  /* set auth_info */

  if ((ret = _gnutls_auth_info_init(session, GNUTLS_CRD_PSK,

            sizeof(psk_auth_info_st), 1)) < 0) {

    gnutls_assert();

    return ret;

  }

  DECR_LEN(data_size, 2);

  hint.size = _gnutls_read_uint16(&data[0]);

  hint.data = &data[2];

  DECR_LEN(data_size, hint.size);

  data += 2 + hint.size;

  ret = _gnutls_proc_ecdh_common_server_kx(session, data, data_size);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  info = _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

  if (info == NULL)

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  if (hint.size > MAX_USERNAME_SIZE)

    return gnutls_assert_val(GNUTLS_E_ILLEGAL_SRP_USERNAME);

  ret = _gnutls_copy_psk_hint(info, hint);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  return 0;

}

#endif /* ENABLE_PSK */