/*

 * Copyright (C) 2001-2012 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/>

 *

 */

#include "gnutls_int.h"

#include "errors.h"

#include "auth.h"

#include "auth.h"

#include "algorithms.h"

#include "auth/cert.h"

#include "auth/psk.h"

#include "auth/srp_kx.h"

#include "auth/anon.h"

#include "datum.h"

/* The functions here are used in order for authentication algorithms

 * to be able to retrieve the needed credentials eg public and private

 * key etc.

 */

/**

 * gnutls_credentials_clear:

 * @session: is a #gnutls_session_t type.

 *

 * Clears all the credentials previously set in this session.

 **/

void gnutls_credentials_clear(gnutls_session_t session)

{

  if (session->key.cred) { /* beginning of the list */

    auth_cred_st *ccred, *ncred;

    ccred = session->key.cred;

    while (ccred != NULL) {

      ncred = ccred->next;

      gnutls_free(ccred);

      ccred = ncred;

    }

    session->key.cred = NULL;

  }

}

/* 

 * This creates a linked list of the form:

 * { algorithm, credentials, pointer to next }

 */

/**

 * gnutls_credentials_set:

 * @session: is a #gnutls_session_t type.

 * @type: is the type of the credentials

 * @cred: the credentials to set

 *

 * Sets the needed credentials for the specified type.  E.g. username,

 * password - or public and private keys etc.  The @cred parameter is

 * a structure that depends on the specified type and on the current

 * session (client or server).

 *

 * In order to minimize memory usage, and share credentials between

 * several threads gnutls keeps a pointer to cred, and not the whole

 * cred structure.  Thus you will have to keep the structure allocated

 * until you call gnutls_deinit().

 *

 * For %GNUTLS_CRD_ANON, @cred should be

 * #gnutls_anon_client_credentials_t in case of a client.  In case of

 * a server it should be #gnutls_anon_server_credentials_t.

 *

 * For %GNUTLS_CRD_SRP, @cred should be #gnutls_srp_client_credentials_t

 * in case of a client, and #gnutls_srp_server_credentials_t, in case

 * of a server.

 *

 * For %GNUTLS_CRD_CERTIFICATE, @cred should be

 * #gnutls_certificate_credentials_t.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 **/

int gnutls_credentials_set(gnutls_session_t session,

         gnutls_credentials_type_t type, void *cred)

{

  auth_cred_st *ccred = NULL, *pcred = NULL;

  int exists = 0;

  if (session->key.cred == NULL) { /* beginning of the list */

    session->key.cred = gnutls_malloc(sizeof(auth_cred_st));

    if (session->key.cred == NULL)

      return GNUTLS_E_MEMORY_ERROR;

    /* copy credentials locally */

    session->key.cred->credentials = cred;

    session->key.cred->next = NULL;

    session->key.cred->algorithm = type;

  } else {

    ccred = session->key.cred;

    while (ccred != NULL) {

      if (ccred->algorithm == type) {

        exists = 1;

        break;

      }

      pcred = ccred;

      ccred = ccred->next;

    }

    /* After this, pcred is not null.

     */

    if (exists == 0) { /* new entry */

      pcred->next = gnutls_malloc(sizeof(auth_cred_st));

      if (pcred->next == NULL)

        return GNUTLS_E_MEMORY_ERROR;

      ccred = pcred->next;

      /* copy credentials locally */

      ccred->credentials = cred;

      ccred->next = NULL;

      ccred->algorithm = type;

    } else { /* modify existing entry */

      ccred->credentials = cred;

    }

  }

  /* sanity tests */

  if (type == GNUTLS_CRD_CERTIFICATE) {

    gnutls_certificate_credentials_t c = cred;

    unsigned i;

    bool allow_tls13 = 0;

    unsigned key_usage;

    if (c != NULL && c->ncerts != 0) {

      for (i = 0; i < c->ncerts; i++) {

        key_usage = get_key_usage(

          session,

          c->certs[i].cert_list[0].pubkey);

        if (key_usage == 0 ||

            (key_usage &

             GNUTLS_KEY_DIGITAL_SIGNATURE)) {

          allow_tls13 = 1;

          break;

        }

      }

      if (session->security_parameters.entity ==

            GNUTLS_SERVER &&

          !c->tls13_ok)

        allow_tls13 = 0;

      if (!allow_tls13) {

        /* to prevent the server random indicate TLS1.3 support */

        session->internals.flags |= INT_FLAG_NO_TLS13;

      }

    }

  }

  return 0;

}

/**

 * gnutls_credentials_get:

 * @session: is a #gnutls_session_t type.

 * @type: is the type of the credentials to return

 * @cred: will contain the credentials.

 *

 * Returns the previously provided credentials structures.

 *

 * For %GNUTLS_CRD_ANON, @cred will be

 * #gnutls_anon_client_credentials_t in case of a client.  In case of

 * a server it should be #gnutls_anon_server_credentials_t.

 *

 * For %GNUTLS_CRD_SRP, @cred will be #gnutls_srp_client_credentials_t

 * in case of a client, and #gnutls_srp_server_credentials_t, in case

 * of a server.

 *

 * For %GNUTLS_CRD_CERTIFICATE, @cred will be

 * #gnutls_certificate_credentials_t.

 *

 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned,

 *   otherwise a negative error code is returned.

 *

 * Since: 3.3.3

 **/

int gnutls_credentials_get(gnutls_session_t session,

         gnutls_credentials_type_t type, void **cred)

{

  const void *_cred;

  _cred = _gnutls_get_cred(session, type);

  if (_cred == NULL)

    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  if (cred)

    *cred = (void *)_cred;

  return 0;

}

/**

 * gnutls_auth_get_type:

 * @session: is a #gnutls_session_t type.

 *

 * Returns type of credentials for the current authentication schema.

 * The returned information is to be used to distinguish the function used

 * to access authentication data.

 *

 * Eg. for CERTIFICATE ciphersuites (key exchange algorithms:

 * %GNUTLS_KX_RSA, %GNUTLS_KX_DHE_RSA), the same function are to be

 * used to access the authentication data.

 *

 * Note that on resumed sessions, this function returns the schema

 * used in the original session authentication.

 *

 * Returns: The type of credentials for the current authentication

 *   schema, a #gnutls_credentials_type_t type.

 **/

gnutls_credentials_type_t gnutls_auth_get_type(gnutls_session_t session)

{

  if (session->security_parameters.entity == GNUTLS_SERVER)

    return gnutls_auth_client_get_type(session);

  else

    return gnutls_auth_server_get_type(session);

}

/**

 * gnutls_auth_server_get_type:

 * @session: is a #gnutls_session_t type.

 *

 * Returns the type of credentials that were used for server authentication.

 * The returned information is to be used to distinguish the function used

 * to access authentication data.

 *

 * Note that on resumed sessions, this function returns the schema

 * used in the original session authentication.

 *

 * Returns: The type of credentials for the server authentication

 *   schema, a #gnutls_credentials_type_t type.

 **/

gnutls_credentials_type_t gnutls_auth_server_get_type(gnutls_session_t session)

{

  return session->security_parameters.server_auth_type;

}

/**

 * gnutls_auth_client_get_type:

 * @session: is a #gnutls_session_t type.

 *

 * Returns the type of credentials that were used for client authentication.

 * The returned information is to be used to distinguish the function used

 * to access authentication data.

 *

 * Note that on resumed sessions, this function returns the schema

 * used in the original session authentication.

 *

 * Returns: The type of credentials for the client authentication

 *   schema, a #gnutls_credentials_type_t type.

 **/

gnutls_credentials_type_t gnutls_auth_client_get_type(gnutls_session_t session)

{

  return session->security_parameters.client_auth_type;

}

/* 

 * This returns a pointer to the linked list. Don't

 * free that!!!

 */

const void *_gnutls_get_kx_cred(gnutls_session_t session,

        gnutls_kx_algorithm_t algo)

{

  int server = session->security_parameters.entity == GNUTLS_SERVER ? 1 :

                      0;

  return _gnutls_get_cred(session, _gnutls_map_kx_get_cred(algo, server));

}

const void *_gnutls_get_cred(gnutls_session_t session,

           gnutls_credentials_type_t type)

{

  auth_cred_st *ccred;

  gnutls_key_st *key = &session->key;

  ccred = key->cred;

  while (ccred != NULL) {

    if (ccred->algorithm == type) {

      break;

    }

    ccred = ccred->next;

  }

  if (ccred == NULL)

    return NULL;

  return ccred->credentials;

}

/*-

 * _gnutls_free_auth_info - Frees the auth info structure

 * @session: is a #gnutls_session_t type.

 *

 * This function frees the auth info structure and sets it to

 * null. It must be called since some structures contain malloced

 * elements.

 -*/

void _gnutls_free_auth_info(gnutls_session_t session)

{

  dh_info_st *dh_info;

  if (session == NULL) {

    gnutls_assert();

    return;

  }

  switch (session->key.auth_info_type) {

  case GNUTLS_CRD_SRP: {

    srp_server_auth_info_t info =

      _gnutls_get_auth_info(session, GNUTLS_CRD_SRP);

    if (info == NULL)

      break;

    gnutls_free(info->username);

    info->username = NULL;

  } break;

#ifdef ENABLE_ANON

  case GNUTLS_CRD_ANON: {

    anon_auth_info_t info =

      _gnutls_get_auth_info(session, GNUTLS_CRD_ANON);

    if (info == NULL)

      break;

    dh_info = &info->dh;

    _gnutls_free_dh_info(dh_info);

  } break;

#endif

  case GNUTLS_CRD_PSK: {

    psk_auth_info_t info =

      _gnutls_get_auth_info(session, GNUTLS_CRD_PSK);

    if (info == NULL)

      break;

    gnutls_free(info->username);

    info->username = NULL;

    info->username_len = 0;

    gnutls_free(info->hint);

    info->hint = NULL;

    info->hint_len = 0;

#ifdef ENABLE_DHE

    dh_info = &info->dh;

    _gnutls_free_dh_info(dh_info);

#endif

  } break;

  case GNUTLS_CRD_CERTIFICATE: {

    unsigned int i;

    cert_auth_info_t info =

      _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);

    if (info == NULL)

      break;

    dh_info = &info->dh;

    for (i = 0; i < info->ncerts; i++) {

      _gnutls_free_datum(&info->raw_certificate_list[i]);

    }

    for (i = 0; i < info->nocsp; i++) {

      _gnutls_free_datum(&info->raw_ocsp_list[i]);

    }

    gnutls_free(info->raw_certificate_list);

    gnutls_free(info->raw_ocsp_list);

    info->ncerts = 0;

    info->nocsp = 0;

#ifdef ENABLE_DHE

    _gnutls_free_dh_info(dh_info);

#endif

  }

  break;

  default:

    return;

  }

  gnutls_free(session->key.auth_info);

  session->key.auth_info_size = 0;

  session->key.auth_info_type = 0;

}

/* This function will create the auth info structure in the key

 * structure if needed.

 *

 * If allow change is !=0 then this will allow changing the auth

 * info structure to a different type.

 */

int _gnutls_auth_info_init(gnutls_session_t session,

         gnutls_credentials_type_t type, int size,

         int allow_change)

{

  if (session->key.auth_info == NULL) {

    session->key.auth_info = gnutls_calloc(1, size);

    if (session->key.auth_info == NULL) {

      gnutls_assert();

      return GNUTLS_E_MEMORY_ERROR;

    }

    session->key.auth_info_type = type;

    session->key.auth_info_size = size;

  } else {

    if (allow_change == 0) {

      /* If the credentials for the current authentication scheme,

       * are not the one we want to set, then it's an error.

       * This may happen if a rehandshake is performed an the

       * ciphersuite which is negotiated has different authentication

       * schema.

       */

      if (type != session->key.auth_info_type) {

        gnutls_assert();

        return GNUTLS_E_INVALID_REQUEST;

      }

    } else {

      /* The new behaviour: Here we reallocate the auth info structure

       * in order to be able to negotiate different authentication

       * types. Ie. perform an auth_anon and then authenticate again using a

       * certificate (in order to prevent revealing the certificate's contents,

       * to passive eavesdropers.

       */

      if (type != session->key.auth_info_type) {

        _gnutls_free_auth_info(session);

        session->key.auth_info = gnutls_calloc(1, size);

        if (session->key.auth_info == NULL) {

          gnutls_assert();

          return GNUTLS_E_MEMORY_ERROR;

        }

        session->key.auth_info_type = type;

        session->key.auth_info_size = size;

      }

    }

  }

  return 0;

}