path: root/source3/libads/sasl.c

/* 
   Unix SMB/CIFS implementation.
   ads sasl code
   Copyright (C) Andrew Tridgell 2001
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program 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 General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

#ifdef HAVE_LDAP

static ADS_STATUS ads_sasl_ntlmssp_wrap(ADS_STRUCT *ads, uint8 *buf, uint32 len)
{
	struct ntlmssp_state *ntlmssp_state =
		(struct ntlmssp_state *)ads->ldap.wrap_private_data;
	ADS_STATUS status;
	NTSTATUS nt_status;
	DATA_BLOB sig;
	uint8 *dptr = ads->ldap.out.buf + (4 + NTLMSSP_SIG_SIZE);

	/* copy the data to the right location */
	memcpy(dptr, buf, len);

	/* create the signature and may encrypt the data */
	if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL) {
		nt_status = ntlmssp_seal_packet(ntlmssp_state,
						dptr, len,
						dptr, len,
						&sig);
	} else {
		nt_status = ntlmssp_sign_packet(ntlmssp_state,
						dptr, len,
						dptr, len,
						&sig);
	}
	status = ADS_ERROR_NT(nt_status);
	if (!ADS_ERR_OK(status)) return status;

	/* copy the signature to the right location */
	memcpy(ads->ldap.out.buf + 4,
	       sig.data, NTLMSSP_SIG_SIZE);

	data_blob_free(&sig);

	/* set how many bytes must be written to the underlying socket */
	ads->ldap.out.left = 4 + NTLMSSP_SIG_SIZE + len;

	return ADS_SUCCESS;
}

static ADS_STATUS ads_sasl_ntlmssp_unwrap(ADS_STRUCT *ads)
{
	struct ntlmssp_state *ntlmssp_state =
		(struct ntlmssp_state *)ads->ldap.wrap_private_data;
	ADS_STATUS status;
	NTSTATUS nt_status;
	DATA_BLOB sig;
	uint8 *dptr = ads->ldap.in.buf + (4 + NTLMSSP_SIG_SIZE);
	uint32 dlen = ads->ldap.in.ofs - (4 + NTLMSSP_SIG_SIZE);

	/* wrap the signature into a DATA_BLOB */
	sig = data_blob_const(ads->ldap.in.buf + 4, NTLMSSP_SIG_SIZE);

	/* verify the signature and maybe decrypt the data */
	if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL) {
		nt_status = ntlmssp_unseal_packet(ntlmssp_state,
						  dptr, dlen,
						  dptr, dlen,
						  &sig);
	} else {
		nt_status = ntlmssp_check_packet(ntlmssp_state,
						 dptr, dlen,
						 dptr, dlen,
						 &sig);
	}
	status = ADS_ERROR_NT(nt_status);
	if (!ADS_ERR_OK(status)) return status;

	/* set the amount of bytes for the upper layer and set the ofs to the data */
	ads->ldap.in.left	= dlen;
	ads->ldap.in.ofs	= 4 + NTLMSSP_SIG_SIZE;

	return ADS_SUCCESS;
}

static void ads_sasl_ntlmssp_disconnect(ADS_STRUCT *ads)
{
	struct ntlmssp_state *ntlmssp_state =
		(struct ntlmssp_state *)ads->ldap.wrap_private_data;

	ntlmssp_end(&ntlmssp_state);

	ads->ldap.wrap_ops = NULL;
	ads->ldap.wrap_private_data = NULL;
}

static const struct ads_saslwrap_ops ads_sasl_ntlmssp_ops = {
	.name		= "ntlmssp",
	.wrap		= ads_sasl_ntlmssp_wrap,
	.unwrap		= ads_sasl_ntlmssp_unwrap,
	.disconnect	= ads_sasl_ntlmssp_disconnect
};

/* 
   perform a LDAP/SASL/SPNEGO/NTLMSSP bind (just how many layers can
   we fit on one socket??)
*/
static ADS_STATUS ads_sasl_spnego_ntlmssp_bind(ADS_STRUCT *ads)
{
	DATA_BLOB msg1 = data_blob_null;
	DATA_BLOB blob = data_blob_null;
	DATA_BLOB blob_in = data_blob_null;
	DATA_BLOB blob_out = data_blob_null;
	struct berval cred, *scred = NULL;
	int rc;
	NTSTATUS nt_status;
	int turn = 1;
	uint32 features = 0;

	struct ntlmssp_state *ntlmssp_state;

	if (!NT_STATUS_IS_OK(nt_status = ntlmssp_client_start(&ntlmssp_state))) {
		return ADS_ERROR_NT(nt_status);
	}
	ntlmssp_state->neg_flags &= ~NTLMSSP_NEGOTIATE_SIGN;

	if (!NT_STATUS_IS_OK(nt_status = ntlmssp_set_username(ntlmssp_state, ads->auth.user_name))) {
		return ADS_ERROR_NT(nt_status);
	}
	if (!NT_STATUS_IS_OK(nt_status = ntlmssp_set_domain(ntlmssp_state, ads->auth.realm))) {
		return ADS_ERROR_NT(nt_status);
	}
	if (!NT_STATUS_IS_OK(nt_status = ntlmssp_set_password(ntlmssp_state, ads->auth.password))) {
		return ADS_ERROR_NT(nt_status);
	}

	switch (ads->ldap.wrap_type) {
	case ADS_SASLWRAP_TYPE_SEAL:
		features = NTLMSSP_FEATURE_SIGN | NTLMSSP_FEATURE_SEAL;
		break;
	case ADS_SASLWRAP_TYPE_SIGN:
		if (ads->auth.flags & ADS_AUTH_SASL_FORCE) {
			features = NTLMSSP_FEATURE_SIGN;
		} else {
			/*
			 * windows servers are broken with sign only,
			 * so we need to use seal here too
			 */
			features = NTLMSSP_FEATURE_SIGN | NTLMSSP_FEATURE_SEAL;
			ads->ldap.wrap_type = ADS_SASLWRAP_TYPE_SEAL;
		}
		break;
	case ADS_SASLWRAP_TYPE_PLAIN:
		break;
	}

	ntlmssp_want_feature(ntlmssp_state, features);

	blob_in = data_blob_null;

	do {
		nt_status = ntlmssp_update(ntlmssp_state, 
					   blob_in, &blob_out);
		data_blob_free(&blob_in);
		if ((NT_STATUS_EQUAL(nt_status, NT_STATUS_MORE_PROCESSING_REQUIRED) 
		     || NT_STATUS_IS_OK(nt_status))
		    && blob_out.length) {
			if (turn == 1) {
				/* and wrap it in a SPNEGO wrapper */
				msg1 = gen_negTokenInit(OID_NTLMSSP, blob_out);
			} else {
				/* wrap it in SPNEGO */
				msg1 = spnego_gen_auth(blob_out);
			}

			data_blob_free(&blob_out);

			cred.bv_val = (char *)msg1.data;
			cred.bv_len = msg1.length;
			scred = NULL;
			rc = ldap_sasl_bind_s(ads->ldap.ld, NULL, "GSS-SPNEGO", &cred, NULL, NULL, &scred);
			data_blob_free(&msg1);
			if ((rc != LDAP_SASL_BIND_IN_PROGRESS) && (rc != 0)) {
				if (scred) {
					ber_bvfree(scred);
				}

				ntlmssp_end(&ntlmssp_state);
				return ADS_ERROR(rc);
			}
			if (scred) {
				blob = data_blob(scred->bv_val, scred->bv_len);
				ber_bvfree(scred);
			} else {
				blob = data_blob_null;
			}

		} else {

			ntlmssp_end(&ntlmssp_state);
			data_blob_free(&blob_out);
			return ADS_ERROR_NT(nt_status);
		}
		
		if ((turn == 1) && 
		    (rc == LDAP_SASL_BIND_IN_PROGRESS)) {
			DATA_BLOB tmp_blob = data_blob_null;
			/* the server might give us back two challenges */
			if (!spnego_parse_challenge(blob, &blob_in, 
						    &tmp_blob)) {

				ntlmssp_end(&ntlmssp_state);
				data_blob_free(&blob);
				DEBUG(3,("Failed to parse challenges\n"));
				return ADS_ERROR_NT(NT_STATUS_INVALID_PARAMETER);
			}
			data_blob_free(&tmp_blob);
		} else if (rc == LDAP_SASL_BIND_IN_PROGRESS) {
			if (!spnego_parse_auth_response(blob, nt_status, OID_NTLMSSP, 
							&blob_in)) {

				ntlmssp_end(&ntlmssp_state);
				data_blob_free(&blob);
				DEBUG(3,("Failed to parse auth response\n"));
				return ADS_ERROR_NT(NT_STATUS_INVALID_PARAMETER);
			}
		}
		data_blob_free(&blob);
		data_blob_free(&blob_out);
		turn++;
	} while (rc == LDAP_SASL_BIND_IN_PROGRESS && !NT_STATUS_IS_OK(nt_status));
	
	/* we have a reference conter on ntlmssp_state, if we are signing
	   then the state will be kept by the signing engine */

	if (ads->ldap.wrap_type > ADS_SASLWRAP_TYPE_PLAIN) {
		ads->ldap.out.min = 4;
		ads->ldap.out.max = 0x0FFFFFFF - NTLMSSP_SIG_SIZE;
		ads->ldap.out.sig_size = NTLMSSP_SIG_SIZE;
		ads->ldap.in.min = 4;
		ads->ldap.in.max = 0x0FFFFFFF;
		ads_setup_sasl_wrapping(ads, &ads_sasl_ntlmssp_ops, ntlmssp_state);
	} else {
		ntlmssp_end(&ntlmssp_state);
	}

	return ADS_ERROR(rc);
}

#ifdef HAVE_GSSAPI
static ADS_STATUS ads_sasl_gssapi_wrap(ADS_STRUCT *ads, uint8 *buf, uint32 len)
{
	gss_ctx_id_t context_handle = ads->ldap.wrap_private_data;
	ADS_STATUS status;
	int gss_rc;
	uint32 minor_status;
	gss_buffer_desc unwrapped, wrapped;
	int conf_req_flag, conf_state;

	unwrapped.value		= buf;
	unwrapped.length	= len;

	/* for now request sign and seal */
	conf_req_flag	= (ads->ldap.wrap_type == ADS_SASLWRAP_TYPE_SEAL);

	gss_rc = gss_wrap(&minor_status, context_handle,
			  conf_req_flag, GSS_C_QOP_DEFAULT,
			  &unwrapped, &conf_state,
			  &wrapped);
	status = ADS_ERROR_GSS(gss_rc, minor_status);
	if (!ADS_ERR_OK(status)) return status;

	if (conf_req_flag && conf_state == 0) {
		return ADS_ERROR_NT(NT_STATUS_ACCESS_DENIED);
	}

	if ((ads->ldap.out.size - 4) < wrapped.length) {
		return ADS_ERROR_NT(NT_STATUS_INTERNAL_ERROR);
	}

	/* copy the wrapped blob to the right location */
	memcpy(ads->ldap.out.buf + 4, wrapped.value, wrapped.length);

	/* set how many bytes must be written to the underlying socket */
	ads->ldap.out.left = 4 + wrapped.length;

	gss_release_buffer(&minor_status, &wrapped);

	return ADS_SUCCESS;
}

static ADS_STATUS ads_sasl_gssapi_unwrap(ADS_STRUCT *ads)
{
	gss_ctx_id_t context_handle = ads->ldap.wrap_private_data;
	ADS_STATUS status;
	int gss_rc;
	uint32 minor_status;
	gss_buffer_desc unwrapped, wrapped;
	int conf_state;

	wrapped.value	= ads->ldap.in.buf + 4;
	wrapped.length	= ads->ldap.in.ofs - 4;

	gss_rc = gss_unwrap(&minor_status, context_handle,
			    &wrapped, &unwrapped,
			    &conf_state, GSS_C_QOP_DEFAULT);
	status = ADS_ERROR_GSS(gss_rc, minor_status);
	if (!ADS_ERR_OK(status)) return status;

	if (ads->ldap.wrap_type == ADS_SASLWRAP_TYPE_SEAL && conf_state == 0) {
		return ADS_ERROR_NT(NT_STATUS_ACCESS_DENIED);
	}

	if (wrapped.length < wrapped.length) {
		return ADS_ERROR_NT(NT_STATUS_INTERNAL_ERROR);
	}

	/* copy the wrapped blob to the right location */
	memcpy(ads->ldap.in.buf + 4, unwrapped.value, unwrapped.length);

	/* set how many bytes must be written to the underlying socket */
	ads->ldap.in.left	= unwrapped.length;
	ads->ldap.in.ofs	= 4;

	gss_release_buffer(&minor_status, &unwrapped);

	return ADS_SUCCESS;
}

static void ads_sasl_gssapi_disconnect(ADS_STRUCT *ads)
{
	gss_ctx_id_t context_handle = ads->ldap.wrap_private_data;
	uint32 minor_status;

	gss_delete_sec_context(&minor_status, &context_handle, GSS_C_NO_BUFFER);

	ads->ldap.wrap_ops = NULL;
	ads->ldap.wrap_private_data = NULL;
}

static const struct ads_saslwrap_ops ads_sasl_gssapi_ops = {
	.name		= "gssapi",
	.wrap		= ads_sasl_gssapi_wrap,
	.unwrap		= ads_sasl_gssapi_unwrap,
	.disconnect	= ads_sasl_gssapi_disconnect
};
#endif

#ifdef HAVE_KRB5
/* 
   perform a LDAP/SASL/SPNEGO/KRB5 bind
*/
static ADS_STATUS ads_sasl_spnego_krb5_bind(ADS_STRUCT *ads, const char *principal)
{
	DATA_BLOB blob = data_blob_null;
	struct berval cred, *scred = NULL;
	DATA_BLOB session_key = data_blob_null;
	int rc;

	rc = spnego_gen_negTokenTarg(principal, ads->auth.time_offset, &blob, &session_key, 0,
				     &ads->auth.tgs_expire);

	if (rc) {
		return ADS_ERROR_KRB5(rc);
	}

	/* now send the auth packet and we should be done */
	cred.bv_val = (char *)blob.data;
	cred.bv_len = blob.length;

	rc = ldap_sasl_bind_s(ads->ldap.ld, NULL, "GSS-SPNEGO", &cred, NULL, NULL, &scred);

	data_blob_free(&blob);
	data_blob_free(&session_key);
	if(scred)
		ber_bvfree(scred);

	return ADS_ERROR(rc);
}
#endif

/* 
   this performs a SASL/SPNEGO bind
*/
static ADS_STATUS ads_sasl_spnego_bind(ADS_STRUCT *ads)
{
	struct berval *scred=NULL;
	int rc, i;
	ADS_STATUS status;
	DATA_BLOB blob;
	char *principal = NULL;
	char *OIDs[ASN1_MAX_OIDS];
#ifdef HAVE_KRB5
	BOOL got_kerberos_mechanism = False;
#endif

	rc = ldap_sasl_bind_s(ads->ldap.ld, NULL, "GSS-SPNEGO", NULL, NULL, NULL, &scred);

	if (rc != LDAP_SASL_BIND_IN_PROGRESS) {
		status = ADS_ERROR(rc);
		goto failed;
	}

	blob = data_blob(scred->bv_val, scred->bv_len);

	ber_bvfree(scred);

#if 0
	file_save("sasl_spnego.dat", blob.data, blob.length);
#endif

	/* the server sent us the first part of the SPNEGO exchange in the negprot 
	   reply */
	if (!spnego_parse_negTokenInit(blob, OIDs, &principal)) {
		data_blob_free(&blob);
		status = ADS_ERROR(LDAP_OPERATIONS_ERROR);
		goto failed;
	}
	data_blob_free(&blob);

	/* make sure the server understands kerberos */
	for (i=0;OIDs[i];i++) {
		DEBUG(3,("ads_sasl_spnego_bind: got OID=%s\n", OIDs[i]));
#ifdef HAVE_KRB5
		if (strcmp(OIDs[i], OID_KERBEROS5_OLD) == 0 ||
		    strcmp(OIDs[i], OID_KERBEROS5) == 0) {
			got_kerberos_mechanism = True;
		}
#endif
		free(OIDs[i]);
	}
	DEBUG(3,("ads_sasl_spnego_bind: got server principal name = %s\n", principal));

#ifdef HAVE_KRB5
	if (!(ads->auth.flags & ADS_AUTH_DISABLE_KERBEROS) &&
	    got_kerberos_mechanism) 
	{
		/* I've seen a child Windows 2000 domain not send 
		   the principal name back in the first round of 
		   the SASL bind reply.  So we guess based on server
		   name and realm.  --jerry  */
		if ( !principal ) {
			if ( ads->server.realm && ads->server.ldap_server ) {
				char *server, *server_realm;
				
				server = SMB_STRDUP( ads->server.ldap_server );
				server_realm = SMB_STRDUP( ads->server.realm );
				
				if ( !server || !server_realm )
					return ADS_ERROR(LDAP_NO_MEMORY);

				strlower_m( server );
				strupper_m( server_realm );				
				asprintf( &principal, "ldap/%s@%s", server, server_realm );

				SAFE_FREE( server );
				SAFE_FREE( server_realm );

				if ( !principal )
					return ADS_ERROR(LDAP_NO_MEMORY);				
			}
			
		}
		
		status = ads_sasl_spnego_krb5_bind(ads, principal);
		if (ADS_ERR_OK(status)) {
			SAFE_FREE(principal);
			return status;
		}

		DEBUG(10,("ads_sasl_spnego_krb5_bind failed with: %s, "
			  "calling kinit\n", ads_errstr(status)));

		status = ADS_ERROR_KRB5(ads_kinit_password(ads)); 

		if (ADS_ERR_OK(status)) {
			status = ads_sasl_spnego_krb5_bind(ads, principal);
		}

		/* only fallback to NTLMSSP if allowed */
		if (ADS_ERR_OK(status) || 
		    !(ads->auth.flags & ADS_AUTH_ALLOW_NTLMSSP)) {
			SAFE_FREE(principal);
			return status;
		}
	}
#endif

	SAFE_FREE(principal);

	/* lets do NTLMSSP ... this has the big advantage that we don't need
	   to sync clocks, and we don't rely on special versions of the krb5 
	   library for HMAC_MD4 encryption */
	return ads_sasl_spnego_ntlmssp_bind(ads);

failed:
	return status;
}

#ifdef HAVE_GSSAPI
#define MAX_GSS_PASSES 3

/* this performs a SASL/gssapi bind
   we avoid using cyrus-sasl to make Samba more robust. cyrus-sasl
   is very dependent on correctly configured DNS whereas
   this routine is much less fragile
   see RFC2078 and RFC2222 for details
*/
static ADS_STATUS ads_sasl_gssapi_bind(ADS_STRUCT *ads)
{
	uint32 minor_status;
	gss_name_t serv_name;
	gss_buffer_desc input_name;
	gss_ctx_id_t context_handle = GSS_C_NO_CONTEXT;
	gss_OID mech_type = GSS_C_NULL_OID;
	gss_buffer_desc output_token, input_token;
	uint32 req_flags, ret_flags;
	int conf_state;
	struct berval cred;
	struct berval *scred = NULL;
	int i=0;
	int gss_rc, rc;
	uint8 *p;
	uint32 max_msg_size = 0;
	char *sname = NULL;
	ADS_STATUS status;
	krb5_principal principal = NULL;
	krb5_context ctx = NULL;
	krb5_enctype enc_types[] = {
#ifdef ENCTYPE_ARCFOUR_HMAC
			ENCTYPE_ARCFOUR_HMAC,
#endif
			ENCTYPE_DES_CBC_MD5,
			ENCTYPE_NULL};
	gss_OID_desc nt_principal = 
	{10, CONST_DISCARD(char *, "\052\206\110\206\367\022\001\002\002\002")};

	/* we need to fetch a service ticket as the ldap user in the
	   servers realm, regardless of our realm */
	asprintf(&sname, "ldap/%s@%s", ads->config.ldap_server_name, ads->config.realm);

	initialize_krb5_error_table();
	status = ADS_ERROR_KRB5(krb5_init_context(&ctx));
	if (!ADS_ERR_OK(status)) {
		SAFE_FREE(sname);
		return status;
	}
	status = ADS_ERROR_KRB5(krb5_set_default_tgs_ktypes(ctx, enc_types));
	if (!ADS_ERR_OK(status)) {
		SAFE_FREE(sname);
		krb5_free_context(ctx);	
		return status;
	}
	status = ADS_ERROR_KRB5(smb_krb5_parse_name(ctx, sname, &principal));
	if (!ADS_ERR_OK(status)) {
		SAFE_FREE(sname);
		krb5_free_context(ctx);	
		return status;
	}

	input_name.value = &principal;
	input_name.length = sizeof(principal);

	gss_rc = gss_import_name(&minor_status, &input_name, &nt_principal, &serv_name);

	/*
	 * The MIT libraries have a *HORRIBLE* bug - input_value.value needs
	 * to point to the *address* of the krb5_principal, and the gss libraries
	 * to a shallow copy of the krb5_principal pointer - so we need to keep
	 * the krb5_principal around until we do the gss_release_name. MIT *SUCKS* !
	 * Just one more way in which MIT engineers screwed me over.... JRA.
	 */

	SAFE_FREE(sname);

	if (gss_rc) {
		krb5_free_principal(ctx, principal);
		krb5_free_context(ctx);	
		return ADS_ERROR_GSS(gss_rc, minor_status);
	}

	input_token.value = NULL;
	input_token.length = 0;

	req_flags = GSS_C_MUTUAL_FLAG | GSS_C_REPLAY_FLAG;
	switch (ads->ldap.wrap_type) {
	case ADS_SASLWRAP_TYPE_SEAL:
		req_flags |= GSS_C_INTEG_FLAG | GSS_C_CONF_FLAG;
		break;
	case ADS_SASLWRAP_TYPE_SIGN:
		req_flags |= GSS_C_INTEG_FLAG;
		break;
	case ADS_SASLWRAP_TYPE_PLAIN:
		break;
	}

	for (i=0; i < MAX_GSS_PASSES; i++) {
		gss_rc = gss_init_sec_context(&minor_status,
					  GSS_C_NO_CREDENTIAL,
					  &context_handle,
					  serv_name,
					  mech_type,
					  req_flags,
					  0,
					  NULL,
					  &input_token,
					  NULL,
					  &output_token,
					  &ret_flags,
					  NULL);

		if (input_token.value) {
			gss_release_buffer(&minor_status, &input_token);
		}

		if (gss_rc && gss_rc != GSS_S_CONTINUE_NEEDED) {
			status = ADS_ERROR_GSS(gss_rc, minor_status);
			goto failed;
		}

		cred.bv_val = (char *)output_token.value;
		cred.bv_len = output_token.length;

		rc = ldap_sasl_bind_s(ads->ldap.ld, NULL, "GSSAPI", &cred, NULL, NULL, 
				      &scred);
		if (rc != LDAP_SASL_BIND_IN_PROGRESS) {
			status = ADS_ERROR(rc);
			goto failed;
		}

		if (output_token.value) {
			gss_release_buffer(&minor_status, &output_token);
		}

		if (scred) {
			input_token.value = scred->bv_val;
			input_token.length = scred->bv_len;
		} else {
			input_token.value = NULL;
			input_token.length = 0;
		}

		if (gss_rc == 0) break;
	}

	gss_rc = gss_unwrap(&minor_status,context_handle,&input_token,&output_token,
			    &conf_state,NULL);
	if (gss_rc) {
		status = ADS_ERROR_GSS(gss_rc, minor_status);
		goto failed;
	}

	gss_release_buffer(&minor_status, &input_token);

	p = (uint8 *)output_token.value;

#if 0
	file_save("sasl_gssapi.dat", output_token.value, output_token.length);
#endif

	if (p) {
		max_msg_size = (p[1]<<16) | (p[2]<<8) | p[3];
	}

	gss_release_buffer(&minor_status, &output_token);

	output_token.length = 4;
	output_token.value = SMB_MALLOC(output_token.length);
	p = (uint8 *)output_token.value;

	*p++ = ads->ldap.wrap_type;
	/* choose the same size as the server gave us */
	*p++ = max_msg_size>>16;
	*p++ = max_msg_size>>8;
	*p++ = max_msg_size;
	/*
	 * we used to add sprintf("dn:%s", ads->config.bind_path) here.
	 * but using ads->config.bind_path is the wrong! It should be
	 * the DN of the user object!
	 *
	 * w2k3 gives an error when we send an incorrect DN, but sending nothing
	 * is ok and matches the information flow used in GSS-SPNEGO.
	 */

	gss_rc = gss_wrap(&minor_status, context_handle,0,GSS_C_QOP_DEFAULT,
			  &output_token, &conf_state,
			  &input_token);
	if (gss_rc) {
		status = ADS_ERROR_GSS(gss_rc, minor_status);
		goto failed;
	}

	free(output_token.value);

	cred.bv_val = (char *)input_token.value;
	cred.bv_len = input_token.length;

	rc = ldap_sasl_bind_s(ads->ldap.ld, NULL, "GSSAPI", &cred, NULL, NULL, 
			      &scred);
	status = ADS_ERROR(rc);

	gss_release_buffer(&minor_status, &input_token);

	if (ads->ldap.wrap_type > ADS_SASLWRAP_TYPE_PLAIN) {
		gss_rc = gss_wrap_size_limit(&minor_status, context_handle,
					     (ads->ldap.wrap_type == ADS_SASLWRAP_TYPE_SEAL),
					     GSS_C_QOP_DEFAULT,
					     max_msg_size, &ads->ldap.out.max);
		if (gss_rc) {
			status = ADS_ERROR_GSS(gss_rc, minor_status);
			goto failed;
		}

		ads->ldap.out.min = 4;
		ads->ldap.out.sig_size = max_msg_size - ads->ldap.out.max;
		ads->ldap.in.min = 4;
		ads->ldap.in.max = max_msg_size;
		ads_setup_sasl_wrapping(ads, &ads_sasl_gssapi_ops, context_handle);
		/* make sure we don't free context_handle */
		context_handle = GSS_C_NO_CONTEXT;
	}
failed:

	gss_release_name(&minor_status, &serv_name);
	if (context_handle != GSS_C_NO_CONTEXT)
		gss_delete_sec_context(&minor_status, &context_handle, GSS_C_NO_BUFFER);
	krb5_free_principal(ctx, principal);
	krb5_free_context(ctx);	

	if(scred)
		ber_bvfree(scred);
	return status;
}
#endif /* HAVE_GGSAPI */

/* mapping between SASL mechanisms and functions */
static struct {
	const char *name;
	ADS_STATUS (*fn)(ADS_STRUCT *);
} sasl_mechanisms[] = {
	{"GSS-SPNEGO", ads_sasl_spnego_bind},
#ifdef HAVE_GSSAPI
	{"GSSAPI", ads_sasl_gssapi_bind}, /* doesn't work with .NET RC1. No idea why */
#endif
	{NULL, NULL}
};

ADS_STATUS ads_sasl_bind(ADS_STRUCT *ads)
{
	const char *attrs[] = {"supportedSASLMechanisms", NULL};
	char **values;
	ADS_STATUS status;
	int i, j;
	LDAPMessage *res;

	/* get a list of supported SASL mechanisms */
	status = ads_do_search(ads, "", LDAP_SCOPE_BASE, "(objectclass=*)", attrs, &res);
	if (!ADS_ERR_OK(status)) return status;

	values = ldap_get_values(ads->ldap.ld, res, "supportedSASLMechanisms");

	if (ads->auth.flags & ADS_AUTH_SASL_SEAL) {
		ads->ldap.wrap_type = ADS_SASLWRAP_TYPE_SEAL;
	} else if (ads->auth.flags & ADS_AUTH_SASL_SIGN) {
		ads->ldap.wrap_type = ADS_SASLWRAP_TYPE_SIGN;
	} else {
		ads->ldap.wrap_type = ADS_SASLWRAP_TYPE_PLAIN;
	}

	/* try our supported mechanisms in order */
	for (i=0;sasl_mechanisms[i].name;i++) {
		/* see if the server supports it */
		for (j=0;values && values[j];j++) {
			if (strcmp(values[j], sasl_mechanisms[i].name) == 0) {
				DEBUG(4,("Found SASL mechanism %s\n", values[j]));
				status = sasl_mechanisms[i].fn(ads);
				ldap_value_free(values);
				ldap_msgfree(res);
				return status;
			}
		}
	}

	ldap_value_free(values);
	ldap_msgfree(res);
	return ADS_ERROR(LDAP_AUTH_METHOD_NOT_SUPPORTED);
}

#endif /* HAVE_LDAP */