path: root/lib/gnutls_cert.c

/*
 *  Copyright (C) 2001,2002,2003 Nikos Mavroyanopoulos
 *
 * 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
 *
 */

/* Some of the stuff needed for Certificate authentication is contained
 * in this file.
 */

#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <auth_cert.h>
#include <gnutls_cert.h>
#include <libtasn1.h>
#include <gnutls_datum.h>
#include <gnutls_mpi.h>
#include <gnutls_global.h>
#include <gnutls_privkey.h>
#include <gnutls_algorithms.h>
#include <gnutls_dh.h>
#include <gnutls_str.h>
#include <gnutls_state.h>
#include <gnutls_auth_int.h>
#include <gnutls_x509.h>
#include <gnutls_extra.h>
#include "x509/compat.h"
#include "x509/x509.h"
#include "x509/mpi.h"


/**
  * gnutls_certificate_free_credentials - Used to free an allocated gnutls_certificate_credentials structure
  * @sc: is an &gnutls_certificate_credentials structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to free (deallocate)
  * the structure.
  *
  * This function does not free any temporary parameters associated
  * with this structure (ie RSA and DH parameters are not freed by
  * this function).
  **/
void gnutls_certificate_free_credentials(gnutls_certificate_credentials sc)
{
	uint i, j;

	for (i = 0; i < sc->ncerts; i++) {
		for (j = 0; j < sc->cert_list_length[i]; j++) {
			_gnutls_free_cert( &sc->cert_list[i][j]);
		}
		gnutls_free( sc->cert_list[i]);
	}

	gnutls_free(sc->cert_list_length);
	gnutls_free(sc->cert_list);

	for (j = 0; j < sc->x509_ncas; j++) {
		gnutls_x509_certificate_deinit( sc->x509_ca_list[j]);
	}

	for (j = 0; j < sc->x509_ncrls; j++) {
		gnutls_x509_crl_deinit( sc->x509_crl_list[j]);
	}

	gnutls_free( sc->x509_ca_list);
	_gnutls_free_datum( &sc->keyring);

	for (i = 0; i < sc->ncerts; i++) {
		_gnutls_free_private_key(sc->pkey[i]);
	}

	gnutls_free( sc->pkey);
	gnutls_free( sc->x509_rdn_sequence.data);

	gnutls_free( sc);
}


/**
  * gnutls_certificate_allocate_credentials - Used to allocate an gnutls_certificate_credentials structure
  * @res: is a pointer to an &gnutls_certificate_credentials structure.
  *
  * This structure is complex enough to manipulate directly thus
  * this helper function is provided in order to allocate
  * the structure.
  **/
int gnutls_certificate_allocate_credentials(gnutls_certificate_credentials * res)
{
	*res = gnutls_calloc(1, sizeof(CERTIFICATE_CREDENTIALS_INT));

	if (*res == NULL)
		return GNUTLS_E_MEMORY_ERROR;

	return 0;
}


/* returns the KX algorithms that are supported by a
 * certificate. (Eg a certificate with RSA params, supports
 * GNUTLS_KX_RSA algorithm).
 * This function also uses the KeyUsage field of the certificate
 * extensions in order to disable unneded algorithms.
 */
int _gnutls_cert_supported_kx(const gnutls_cert* cert, gnutls_kx_algorithm ** alg,
			      int *alg_size)
{
	gnutls_kx_algorithm kx;
	int i;
	gnutls_pk_algorithm pk;
	gnutls_kx_algorithm kxlist[MAX_ALGOS];

	i = 0;
	for (kx = 0; kx < MAX_ALGOS; kx++) {
		pk = _gnutls_map_pk_get_pk(kx);
		if (pk == cert->subject_pk_algorithm) {
			/* then check key usage */
			if (_gnutls_check_key_usage(cert, kx) == 0) {
				kxlist[i] = kx;
				i++;
			}
		}
	}

	if (i==0) {
		gnutls_assert();
		return GNUTLS_E_INVALID_REQUEST;
	}

	*alg = gnutls_calloc(1, sizeof(gnutls_kx_algorithm) * i);
	if (*alg == NULL)
		return GNUTLS_E_MEMORY_ERROR;

	*alg_size = i;

	memcpy(*alg, kxlist, i * sizeof(gnutls_kx_algorithm));

	return 0;
}


/**
  * gnutls_certificate_server_set_request - Used to set whether to request a client certificate
  * @session: is an &gnutls_session structure.
  * @req: is one of GNUTLS_CERT_REQUEST, GNUTLS_CERT_REQUIRE
  *
  * This function specifies if we (in case of a server) are going
  * to send a certificate request message to the client. If 'req'
  * is GNUTLS_CERT_REQUIRE then the server will return an error if
  * the peer does not provide a certificate. If you do not
  * call this function then the client will not be asked to
  * send a certificate.
  **/
void gnutls_certificate_server_set_request(gnutls_session session,
					    gnutls_certificate_request req)
{
	session->internals.send_cert_req = req;
}

/**
  * gnutls_certificate_client_set_select_function - Used to set a callback while selecting the proper (client) certificate
  * @session: is a &gnutls_session structure.
  * @func: is the callback function
  *
  * The callback's function form is:
  * int (*callback)(gnutls_session, gnutls_datum *client_cert, int ncerts, gnutls_datum* req_ca_cert, int nreqs);
  *
  * 'client_cert' contains 'ncerts' gnutls_datum structures which hold
  * the raw certificates (DER for X.509 or binary for OpenPGP), of the
  * client.
  *
  * 'req_ca_cert', is only used in X.509 certificates. 
  * Contains a list with the CA names that the server considers trusted. 
  * Normaly we should send a certificate that is signed
  * by one of these CAs. These names are DER encoded. To get a more
  * meaningful value use the function gnutls_x509_rdn_get().
  *
  * This function specifies what we, in case of a client, are going
  * to do when we have to send a certificate. If this callback
  * function is not provided then gnutls will automaticaly try to
  * find an appropriate certificate to send. The appropriate certificate
  * is chosen based on the CAs sent by the server, and the requested
  * public key algorithms.
  *
  * If the callback function is provided then gnutls will call it
  * once with NULL parameters. If the callback function returns
  * a positive or zero number then gnutls will attempt to automaticaly
  * choose the appropriate certificate. If gnutls fails to find an appropriate
  * certificate, then it will call the callback function again with the 
  * appropriate parameters.
  *
  * In case the callback returned a negative number then gnutls will
  * not attempt to choose the appropriate certificate and will call again
  * the callback function with the appropriate parameters, and rely
  * only to the return value of the callback function.
  *
  * The callback function should return the index of the certificate
  * choosen by the user. -1 indicates that the user
  * does not want to use client authentication.
  *
  * This function returns 0 on success.
  **/
void gnutls_certificate_client_set_select_function(gnutls_session session,
					     certificate_client_select_func
					     * func)
{
	session->internals.client_cert_callback = func;
}

/**
  * gnutls_certificate_server_set_select_function - Used to set a callback while selecting the proper (server) certificate
  * @session: is a &gnutls_session structure.
  * @func: is the callback function
  *
  * The callback's function form is:
  * int (*callback)(gnutls_session, gnutls_datum *server_cert, int ncerts);
  *
  * 'server_cert' contains 'ncerts' gnutls_datum structures which hold
  * the raw certificate (DER encoded in X.509) of the server. 
  *
  * This function specifies what we, in case of a server, are going
  * to do when we have to send a certificate. If this callback
  * function is not provided then gnutls will automaticaly try to
  * find an appropriate certificate to send. (actually send the first in the list)
  *
  * In case the callback returned a negative number then gnutls will
  * not attempt to choose the appropriate certificate and the caller function
  * will fail.
  *
  * The callback function will only be called once per handshake.
  * The callback function should return the index of the certificate
  * choosen by the server. -1 indicates an error.
  *
  **/
void gnutls_certificate_server_set_select_function(gnutls_session session,
					     certificate_server_select_func
					     * func)
{
	session->internals.server_cert_callback = func;
}

/* These are set by the gnutls_extra library's initialization function.
 */

OPENPGP_KEY_CREATION_TIME_FUNC _E_gnutls_openpgp_extract_key_creation_time = NULL;
OPENPGP_KEY_EXPIRATION_TIME_FUNC _E_gnutls_openpgp_extract_key_expiration_time = NULL;
OPENPGP_VERIFY_KEY_FUNC _E_gnutls_openpgp_verify_key = NULL;

/*-
  * _gnutls_openpgp_cert_verify_peers - This function returns the peer's certificate status
  * @session: is a gnutls session
  *
  * This function will try to verify the peer's certificate and return it's status (TRUSTED, INVALID etc.). 
  * Returns a negative error code in case of an error, or GNUTLS_E_NO_CERTIFICATE_FOUND if no certificate was sent.
  *
  -*/
int _gnutls_openpgp_cert_verify_peers(gnutls_session session)
{
	CERTIFICATE_AUTH_INFO info;
	const gnutls_certificate_credentials cred;
	int verify;
	int peer_certificate_list_size;

	CHECK_AUTH(GNUTLS_CRD_CERTIFICATE, GNUTLS_E_INVALID_REQUEST);

	info = _gnutls_get_auth_info(session);
	if (info == NULL)
		return GNUTLS_E_INVALID_REQUEST;

	cred = _gnutls_get_cred(session->key, GNUTLS_CRD_CERTIFICATE, NULL);
	if (cred == NULL) {
		gnutls_assert();
		return GNUTLS_E_INSUFICIENT_CREDENTIALS;
	}

	if (info->raw_certificate_list == NULL || info->ncerts == 0) {
		gnutls_assert();
		return GNUTLS_E_NO_CERTIFICATE_FOUND;
	}
	
	/* generate a list of gnutls_certs based on the auth info
	 * raw certs.
	 */
	peer_certificate_list_size = info->ncerts;

	if (peer_certificate_list_size != 1) {
		gnutls_assert();
		return GNUTLS_E_INTERNAL_ERROR;
	}
	
	/* Verify certificate 
	 */
	if (_E_gnutls_openpgp_verify_key==NULL) {
		gnutls_assert();
		return GNUTLS_E_INIT_LIBEXTRA;
	}
	verify = _E_gnutls_openpgp_verify_key( cred->pgp_trustdb, &cred->keyring, &info->raw_certificate_list[0],
				      peer_certificate_list_size);

	if (verify < 0) {
		gnutls_assert();
		return verify;
	}


	return verify;
}

/**
  * gnutls_certificate_verify_peers - This function returns the peer's certificate verification status
  * @session: is a gnutls session
  *
  * This function will try to verify the peer's certificate and return it's status (trusted, invalid etc.).
  * However you must also check the peer's name in order to check if the verified certificate belongs to the
  * actual peer.
  *
  * The return value should be one or more of the gnutls_certificate_status
  * enumerated elements bitwise or'd. This is the same as
  * gnutls_x509_verify_certificate().
  *
  **/
int gnutls_certificate_verify_peers(gnutls_session session)
{
	CERTIFICATE_AUTH_INFO info;

	CHECK_AUTH(GNUTLS_CRD_CERTIFICATE, GNUTLS_E_INVALID_REQUEST);

	info = _gnutls_get_auth_info(session);
	if (info == NULL) {
		gnutls_assert();
		return GNUTLS_E_NO_CERTIFICATE_FOUND;
	}
	
	if (info->raw_certificate_list == NULL || info->ncerts == 0)
		return GNUTLS_E_NO_CERTIFICATE_FOUND;

	switch( gnutls_certificate_type_get( session)) {
		case GNUTLS_CRT_X509:
			return _gnutls_x509_cert_verify_peers( session);
		case GNUTLS_CRT_OPENPGP:
			return _gnutls_openpgp_cert_verify_peers( session);
		default:
			return GNUTLS_E_INVALID_REQUEST;
	}
}

/**
  * gnutls_certificate_expiration_time_peers - This function returns the peer's certificate expiration time
  * @session: is a gnutls session
  *
  * This function will return the peer's certificate expiration time.
  *
  * Returns (time_t) -1 on error.
  *
  **/
time_t gnutls_certificate_expiration_time_peers(gnutls_session session)
{
	CERTIFICATE_AUTH_INFO info;

	CHECK_AUTH(GNUTLS_CRD_CERTIFICATE, GNUTLS_E_INVALID_REQUEST);

	info = _gnutls_get_auth_info(session);
	if (info == NULL) {
		gnutls_assert();
		return (time_t) -1;
	}

	if (info->raw_certificate_list == NULL || info->ncerts == 0) {
		gnutls_assert();
		return (time_t) -1;
	}

	switch( gnutls_certificate_type_get( session)) {
		case GNUTLS_CRT_X509:
			return gnutls_x509_extract_certificate_expiration_time(
				&info->raw_certificate_list[0]);
		case GNUTLS_CRT_OPENPGP:
			if (_E_gnutls_openpgp_extract_key_expiration_time==NULL)
				return (time_t)-1;
			return _E_gnutls_openpgp_extract_key_expiration_time(
				&info->raw_certificate_list[0]);
		default:
			return (time_t)-1;
	}
}

/**
  * gnutls_certificate_activation_time_peers - This function returns the peer's certificate activation time
  * @session: is a gnutls session
  *
  * This function will return the peer's certificate activation time.
  * This is the creation time for openpgp keys.
  *
  * Returns (time_t) -1 on error.
  *
  **/
time_t gnutls_certificate_activation_time_peers(gnutls_session session)
{
	CERTIFICATE_AUTH_INFO info;

	CHECK_AUTH(GNUTLS_CRD_CERTIFICATE, GNUTLS_E_INVALID_REQUEST);

	info = _gnutls_get_auth_info(session);
	if (info == NULL) {
		gnutls_assert();
		return (time_t) -1;
	}
	
	if (info->raw_certificate_list == NULL || info->ncerts == 0) {
		gnutls_assert();
		return (time_t) -1;
	}

	switch( gnutls_certificate_type_get( session)) {
		case GNUTLS_CRT_X509:
			return gnutls_x509_extract_certificate_activation_time(
				&info->raw_certificate_list[0]);
		case GNUTLS_CRT_OPENPGP:
			if (_E_gnutls_openpgp_extract_key_creation_time==NULL)
				return (time_t)-1;
			return _E_gnutls_openpgp_extract_key_creation_time(
				&info->raw_certificate_list[0]);
		default:
			return (time_t)-1;
	}
}


/* This function will convert a der certificate, to a format
 * (structure) that gnutls can understand and use. Actually the
 * important thing on this function is that it extracts the 
 * certificate's (public key) parameters.
 *
 * The noext flag is used to complete the handshake even if the
 * extensions found in the certificate are unsupported and critical. 
 * The critical extensions will be catched by the verification functions.
 */
int _gnutls_x509_cert2gnutls_cert(gnutls_cert * gcert, const gnutls_datum *derCert,
	int flags /* OR of ConvFlags */)
{
	int ret = 0;
	gnutls_x509_certificate cert;
	
	ret = gnutls_x509_certificate_init( &cert);
	if ( ret < 0) {
		gnutls_assert();
		return ret;
	}

	ret = gnutls_x509_certificate_import( cert, derCert, GNUTLS_X509_FMT_DER);
	if ( ret < 0) {
		gnutls_assert();
		gnutls_x509_certificate_deinit( cert);
		return ret;
	}
	
	memset(gcert, 0, sizeof(gnutls_cert));
	gcert->cert_type = GNUTLS_CRT_X509;

	if ( !(flags & CERT_NO_COPY)) {
		if (_gnutls_set_datum(&gcert->raw, derCert->data, derCert->size) < 0) {
			gnutls_assert();
			gnutls_x509_certificate_deinit( cert);
			return GNUTLS_E_MEMORY_ERROR;
		}
	} else
		/* now we have 0 or a bitwise or of things to decode */
		flags ^= CERT_NO_COPY;


	if (flags & CERT_ONLY_EXTENSIONS || flags == 0) {
		gnutls_x509_certificate_get_key_usage( cert, &gcert->keyUsage, NULL);
		gcert->version = gnutls_x509_certificate_get_version( cert);
	}
	gcert->subject_pk_algorithm = gnutls_x509_certificate_get_pk_algorithm( cert, NULL);

	if (flags & CERT_ONLY_PUBKEY || flags == 0) {
		gcert->params_size = MAX_PARAMS_SIZE;
		ret = _gnutls_x509_certificate_get_mpis( cert, gcert->params, &gcert->params_size);
		if (ret < 0) {
			gnutls_assert();
			gnutls_x509_certificate_deinit( cert);
			return ret;
		}
	}

	gnutls_x509_certificate_deinit( cert);

	return 0;

}

void _gnutls_free_cert(gnutls_cert *cert)
{
	int i;

	for (i = 0; i < cert->params_size; i++) {
		_gnutls_mpi_release( &cert->params[i]);
	}

	_gnutls_free_datum(&cert->raw);

	return;
}

/* Returns the issuer's Distinguished name in odn, of the certificate 
 * specified in cert.
 */
int _gnutls_cert_get_dn(gnutls_cert * cert, gnutls_datum * odn )
{
	ASN1_TYPE dn;
	int len, result;
	int start, end;

	if ((result=_gnutls_asn1_create_element
	    (_gnutls_get_pkix(), "PKIX1.Certificate", &dn,
	     "dn")) != ASN1_SUCCESS) {
		gnutls_assert();
		return _gnutls_asn2err(result);
	}

	result = asn1_der_decoding(&dn, cert->raw.data, cert->raw.size, NULL);
	if (result != ASN1_SUCCESS) {
		/* couldn't decode DER */
		gnutls_assert();
		asn1_delete_structure(&dn);
		return _gnutls_asn2err(result);
	}

	result = asn1_der_decoding_startEnd(dn, cert->raw.data, cert->raw.size,
					"dn.tbsCertificate.issuer", &start,
					&end);

	if (result != ASN1_SUCCESS) {
		/* couldn't decode DER */
		gnutls_assert();
		asn1_delete_structure(&dn);
		return _gnutls_asn2err(result);
	}
	asn1_delete_structure(&dn);

	len = end - start + 1;

	odn->size = len;
	odn->data = &cert->raw.data[start];

	return 0;
}