auth2-gss.c - third_party/openssh-portable - Git at Google

 /*	$OpenBSD: auth2-gss.c,v 1.3 2003/09/01 20:44:54 markus Exp $	*/

 /*
  * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #include "includes.h"

 #ifdef GSSAPI

 #include "auth.h"
 #include "ssh2.h"
 #include "xmalloc.h"
 #include "log.h"
 #include "dispatch.h"
 #include "servconf.h"
 #include "compat.h"
 #include "packet.h"
 #include "monitor_wrap.h"

 #include "ssh-gss.h"

 extern ServerOptions options;

 static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
 static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
 static void input_gssapi_errtok(int, u_int32_t, void *);

 /*
  * We only support those mechanisms that we know about (ie ones that we know
  * how to check local user kuserok and the like
  */
 static int
 userauth_gssapi(Authctxt *authctxt)
 {
 	gss_OID_desc oid = {0, NULL};
 	Gssctxt *ctxt = NULL;
 	int mechs;
 	gss_OID_set supported;
 	int present;
 	OM_uint32 ms;
 	u_int len;
 	char *doid = NULL;

 	if (!authctxt->valid || authctxt->user == NULL)
 		return (0);

 	mechs = packet_get_int();
 	if (mechs == 0) {
 		debug("Mechanism negotiation is not supported");
 		return (0);
 	}

 	ssh_gssapi_supported_oids(&supported);
 	do {
 		mechs--;

 		if (doid)
 			xfree(doid);

 		doid = packet_get_string(&len);

 		if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
 			logit("Mechanism OID received using the old encoding form");
 			oid.elements = doid;
 			oid.length = len;
 		} else {
 			oid.elements = doid + 2;
 			oid.length   = len - 2;
 		}
 		gss_test_oid_set_member(&ms, &oid, supported, &present);
 	} while (mechs > 0 && !present);

 	gss_release_oid_set(&ms, &supported);

 	if (!present) {
 		xfree(doid);
 		return (0);
 	}

 	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
 		xfree(doid);
 		return (0);
 	}

 	authctxt->methoddata=(void *)ctxt;

 	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

 	/* Return OID in same format as we received it*/
 	packet_put_string(doid, len);

 	packet_send();
 	xfree(doid);

 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
 	authctxt->postponed = 1;

 	return (0);
 }

 static void
 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
 {
 	Authctxt *authctxt = ctxt;
 	Gssctxt *gssctxt;
 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 	gss_buffer_desc recv_tok;
 	OM_uint32 maj_status, min_status;
 	u_int len;

 	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
 		fatal("No authentication or GSSAPI context");

 	gssctxt = authctxt->methoddata;
 	recv_tok.value = packet_get_string(&len);
 	recv_tok.length = len; /* u_int vs. size_t */

 	packet_check_eom();

 	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
 	    &send_tok, NULL));

 	xfree(recv_tok.value);

 	if (GSS_ERROR(maj_status)) {
 		if (send_tok.length != 0) {
 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
 			packet_put_string(send_tok.value, send_tok.length);
 			packet_send();
 		}
 		authctxt->postponed = 0;
 		dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 		userauth_finish(authctxt, 0, "gssapi");
 	} else {
 		if (send_tok.length != 0) {
 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
 			packet_put_string(send_tok.value, send_tok.length);
 			packet_send();
 		}
 		if (maj_status == GSS_S_COMPLETE) {
 			dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 			dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
 				     &input_gssapi_exchange_complete);
 		}
 	}

 	gss_release_buffer(&min_status, &send_tok);
 }

 static void
 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
 {
 	Authctxt *authctxt = ctxt;
 	Gssctxt *gssctxt;
 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
 	gss_buffer_desc recv_tok;
 	OM_uint32 maj_status;
 	u_int len;

 	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
 		fatal("No authentication or GSSAPI context");

 	gssctxt = authctxt->methoddata;
 	recv_tok.value = packet_get_string(&len);
 	recv_tok.length = len;

 	packet_check_eom();

 	/* Push the error token into GSSAPI to see what it says */
 	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
 	    &send_tok, NULL));

 	xfree(recv_tok.value);

 	/* We can't return anything to the client, even if we wanted to */
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);

 	/* The client will have already moved on to the next auth */

 	gss_release_buffer(&maj_status, &send_tok);
 }

 /*
  * This is called when the client thinks we've completed authentication.
  * It should only be enabled in the dispatch handler by the function above,
  * which only enables it once the GSSAPI exchange is complete.
  */

 static void
 input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
 {
 	Authctxt *authctxt = ctxt;
 	Gssctxt *gssctxt;
 	int authenticated;

 	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
 		fatal("No authentication or GSSAPI context");

 	gssctxt = authctxt->methoddata;

 	/*
 	 * We don't need to check the status, because the stored credentials
 	 * which userok uses are only populated once the context init step
 	 * has returned complete.
 	 */

 	packet_check_eom();

 	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));

 	authctxt->postponed = 0;
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
 	userauth_finish(authctxt, authenticated, "gssapi");
 }

 Authmethod method_gssapi = {
 	"gssapi",
 	userauth_gssapi,
 	&options.gss_authentication
 };

 #endif /* GSSAPI */
	/* $OpenBSD: auth2-gss.c,v 1.3 2003/09/01 20:44:54 markus Exp $ */

	/*
	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in the
	* documentation and/or other materials provided with the distribution.
	*
	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#include "includes.h"

	#ifdef GSSAPI

	#include "auth.h"
	#include "ssh2.h"
	#include "xmalloc.h"
	#include "log.h"
	#include "dispatch.h"
	#include "servconf.h"
	#include "compat.h"
	#include "packet.h"
	#include "monitor_wrap.h"

	#include "ssh-gss.h"

	extern ServerOptions options;

	static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
	static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
	static void input_gssapi_errtok(int, u_int32_t, void *);

	/*
	* We only support those mechanisms that we know about (ie ones that we know
	* how to check local user kuserok and the like
	*/
	static int
	userauth_gssapi(Authctxt *authctxt)
	{
	gss_OID_desc oid = {0, NULL};
	Gssctxt *ctxt = NULL;
	int mechs;
	gss_OID_set supported;
	int present;
	OM_uint32 ms;
	u_int len;
	char *doid = NULL;

	if (!authctxt->valid \|\| authctxt->user == NULL)
	return (0);

	mechs = packet_get_int();
	if (mechs == 0) {
	debug("Mechanism negotiation is not supported");
	return (0);
	}

	ssh_gssapi_supported_oids(&supported);
	do {
	mechs--;

	if (doid)
	xfree(doid);

	doid = packet_get_string(&len);

	if (doid[0] != SSH_GSS_OIDTYPE \|\| doid[1] != len-2) {
	logit("Mechanism OID received using the old encoding form");
	oid.elements = doid;
	oid.length = len;
	} else {
	oid.elements = doid + 2;
	oid.length = len - 2;
	}
	gss_test_oid_set_member(&ms, &oid, supported, &present);
	} while (mechs > 0 && !present);

	gss_release_oid_set(&ms, &supported);

	if (!present) {
	xfree(doid);
	return (0);
	}

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
	xfree(doid);
	return (0);
	}

	authctxt->methoddata=(void *)ctxt;

	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

	/* Return OID in same format as we received it*/
	packet_put_string(doid, len);

	packet_send();
	xfree(doid);

	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
	authctxt->postponed = 1;

	return (0);
	}

	static void
	input_gssapi_token(int type, u_int32_t plen, void *ctxt)
	{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok;
	OM_uint32 maj_status, min_status;
	u_int len;

	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;
	recv_tok.value = packet_get_string(&len);
	recv_tok.length = len; /* u_int vs. size_t */

	packet_check_eom();

	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	&send_tok, NULL));

	xfree(recv_tok.value);

	if (GSS_ERROR(maj_status)) {
	if (send_tok.length != 0) {
	packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
	packet_put_string(send_tok.value, send_tok.length);
	packet_send();
	}
	authctxt->postponed = 0;
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	userauth_finish(authctxt, 0, "gssapi");
	} else {
	if (send_tok.length != 0) {
	packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
	packet_put_string(send_tok.value, send_tok.length);
	packet_send();
	}
	if (maj_status == GSS_S_COMPLETE) {
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
	&input_gssapi_exchange_complete);
	}
	}

	gss_release_buffer(&min_status, &send_tok);
	}

	static void
	input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
	{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok;
	OM_uint32 maj_status;
	u_int len;

	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;
	recv_tok.value = packet_get_string(&len);
	recv_tok.length = len;

	packet_check_eom();

	/* Push the error token into GSSAPI to see what it says */
	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	&send_tok, NULL));

	xfree(recv_tok.value);

	/* We can't return anything to the client, even if we wanted to */
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);

	/* The client will have already moved on to the next auth */

	gss_release_buffer(&maj_status, &send_tok);
	}

	/*
	* This is called when the client thinks we've completed authentication.
	* It should only be enabled in the dispatch handler by the function above,
	* which only enables it once the GSSAPI exchange is complete.
	*/

	static void
	input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
	{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	int authenticated;

	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;

	/*
	* We don't need to check the status, because the stored credentials
	* which userok uses are only populated once the context init step
	* has returned complete.
	*/

	packet_check_eom();

	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));

	authctxt->postponed = 0;
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated, "gssapi");
	}

	Authmethod method_gssapi = {
	"gssapi",
	userauth_gssapi,
	&options.gss_authentication
	};

	#endif /* GSSAPI */