path: root/lib/gnutls_auth.c

/*
 * Copyright (C) 2001,2002,2003 Nikos Mavroyanopoulos
 * Copyright (C) 2004 Free Software Foundation
 *
 * This file is part of GNUTLS.
 *
 *  The GNUTLS library 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 */

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_auth.h"
#include "gnutls_auth_int.h"
#include "gnutls_algorithms.h"
#include "auth_cert.h"
#include <gnutls_datum.h>

#include "auth_anon.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 - Clears all the credentials previously set
  * @session: is a &gnutls_session structure.
  *
  * Clears all the credentials previously set in this session.
  *
  **/
void gnutls_credentials_clear(gnutls_session session)
{
    if (session->key && 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 - Sets the needed credentials for the specified authentication algorithm.
  * @session: is a &gnutls_session structure.
  * @type: is the type of the credentials
  * @cred: is a pointer to a structure.
  *
  * Sets the needed credentials for the specified type.
  * Eg username, password - or public and private keys etc.  
  * The (void* 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 in case of a client.
  * In case of a server it should be gnutls_anon_server_credentials.
  * 
  * For GNUTLS_CRD_SRP cred should be gnutls_srp_client_credentials
  * in case of a client, and gnutls_srp_server_credentials, in case
  * of a server.
  *
  * For GNUTLS_CRD_CERTIFICATE cred should be gnutls_certificate_credentials.
  *
  **/
int gnutls_credentials_set(gnutls_session session,
			   gnutls_credentials_type 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 */
	    gnutls_free(ccred->credentials);
	    ccred->credentials = cred;
	}
    }

    return 0;
}

/**
  * gnutls_auth_get_type - Returns the type of credentials for the current authentication schema.
  * @session: is a &gnutls_session structure.
  *
  * 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: KX_RSA, KX_DHE_RSA),
  * the same function are to be used to access the authentication data.
  **/
gnutls_credentials_type gnutls_auth_get_type(gnutls_session session)
{
/* This is not the credentials we must set, but the authentication data
 * we get by the peer, so it should be reversed.
 */
    int server =
	session->security_parameters.entity == GNUTLS_SERVER ? 0 : 1;

    return
	_gnutls_map_kx_get_cred(_gnutls_cipher_suite_get_kx_algo
				(&session->security_parameters.
				 current_cipher_suite), server);
}

/**
  * gnutls_auth_server_get_type - Returns the type of credentials for the server authentication schema.
  * @session: is a &gnutls_session structure.
  *
  * 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.
  * 
  **/
gnutls_credentials_type gnutls_auth_server_get_type(gnutls_session session)
{
    return
	_gnutls_map_kx_get_cred(_gnutls_cipher_suite_get_kx_algo
				(&session->security_parameters.
				 current_cipher_suite), 1);
}

/**
  * gnutls_auth_client_get_type - Returns the type of credentials for the client authentication schema.
  * @session: is a &gnutls_session structure.
  *
  * 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.
  * 
  **/
gnutls_credentials_type gnutls_auth_client_get_type(gnutls_session session)
{
    return
	_gnutls_map_kx_get_cred(_gnutls_cipher_suite_get_kx_algo
				(&session->security_parameters.
				 current_cipher_suite), 0);
}


/* 
 * This returns a pointer to the linked list. Don't
 * free that!!!
 */
const void *_gnutls_get_kx_cred(gnutls_session session,
				gnutls_kx_algorithm algo, int *err)
{
    int server =
	session->security_parameters.entity == GNUTLS_SERVER ? 1 : 0;

    return _gnutls_get_cred(session->key,
			    _gnutls_map_kx_get_cred(algo, server), err);
}

const void *_gnutls_get_cred(gnutls_key_st key,
			     gnutls_credentials_type type, int *err)
{
    const void *retval = NULL;
    int _err = -1;
    auth_cred_st *ccred;

    if (key == NULL)
	goto out;

    ccred = key->cred;
    while (ccred != NULL) {
	if (ccred->algorithm == type) {
	    break;
	}
	ccred = ccred->next;
    }
    if (ccred == NULL)
	goto out;

    _err = 0;
    retval = ccred->credentials;

  out:
    if (err != NULL)
	*err = _err;
    return retval;
}

/*-
  * _gnutls_get_auth_info - Returns a pointer to authentication information.
  * @session: is a &gnutls_session structure.
  *
  * This function must be called after a succesful gnutls_handshake().
  * Returns a pointer to authentication information. That information
  * is data obtained by the handshake protocol, the key exchange algorithm,
  * and the TLS extensions messages.
  *
  * In case of GNUTLS_CRD_ANON returns a type of &anon_(server/client)_auth_info_t;
  * In case of GNUTLS_CRD_CERTIFICATE returns a type of &cert_auth_info_t;
  * In case of GNUTLS_CRD_SRP returns a type of &srp_(server/client)_auth_info_t;
  -*/
void *_gnutls_get_auth_info(gnutls_session session)
{
    return session->key->auth_info;
}

/*-
  * _gnutls_free_auth_info - Frees the auth info structure
  * @session: is a &gnutls_session structure.
  *
  * 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 session)
{
    if (session == NULL || session->key == NULL) {
	gnutls_assert();
	return;
    }

    switch (session->key->auth_info_type) {
    case GNUTLS_CRD_SRP:
    case GNUTLS_CRD_ANON:

	break;
    case GNUTLS_CRD_CERTIFICATE:{
	    unsigned int i;
	    cert_auth_info_t info = _gnutls_get_auth_info(session);

	    if (info == NULL)
		break;
	    for (i = 0; i < info->ncerts; i++) {
		_gnutls_free_datum(&info->raw_certificate_list[i]);
	    }

	    gnutls_free(info->raw_certificate_list);
	    info->raw_certificate_list = NULL;
	    info->ncerts = 0;
	}


	break;
    default:
	return;

    }

    gnutls_free(session->key->auth_info);
    session->key->auth_info = NULL;
    session->key->auth_info_size = 0;
    session->key->auth_info_type = 0;

}

/* This function will set the auth info structure in the key
 * structure.
 * If allow change is !=0 then this will allow changing the auth
 * info structure to a different type.
 */
int _gnutls_auth_info_set(gnutls_session session,
			  gnutls_credentials_type 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 (gnutls_auth_get_type(session) !=
		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 (gnutls_auth_get_type(session) !=
		session->key->auth_info_type) {
		session->key->auth_info =
		    gnutls_realloc_fast(session->key->auth_info, size);
		if (session->key->auth_info == NULL) {
		    gnutls_assert();
		    return GNUTLS_E_MEMORY_ERROR;
		}
		memset(session->key->auth_info, 0, size);
		session->key->auth_info_type = type;
		session->key->auth_info_size = size;
	    }
	}
    }
    return 0;
}

/* this function will copy an mpi_t key to 
 * opaque data.
 */
int _gnutls_generate_session_key(gnutls_key_st key)
{
    size_t tmp;

    _gnutls_mpi_print(NULL, &tmp, key->KEY);
    key->key.data = gnutls_secure_malloc(tmp);
    if (key->key.data == NULL) {
	return GNUTLS_E_MEMORY_ERROR;
    }
    _gnutls_mpi_print(key->key.data, &tmp, key->KEY);

    key->key.size = tmp;
    return 0;
}