[gssapi-openssh.git] / openssh / auth2-gss.c

/* $OpenBSD: auth2-gss.c,v 1.15 2006/08/03 03:34:41 deraadt 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 <sys/types.h>

#include <stdarg.h>

#include "xmalloc.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "ssh2.h"
#include "log.h"
#include "dispatch.h"
#include "buffer.h"
#include "servconf.h"
#include "packet.h"
#include "ssh-gss.h"
#include "monitor_wrap.h"

extern ServerOptions options;

static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
static void input_gssapi_mic(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 *);

static int gssapi_with_mic = 1;	/* flag to toggle "gssapi-with-mic" vs.
				   "gssapi" */

static int
userauth_external(Authctxt *authctxt)
{
        packet_check_eom();

	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
		return(PRIVSEP(ssh_gssapi_userok(authctxt->user)));
	}
	return 0;
}

/* 
 * The 'gssapi_keyex' userauth mechanism.
 */
static int
userauth_gsskeyex(Authctxt *authctxt)
{
	int authenticated = 0;
	Buffer b, b2;
	gss_buffer_desc mic, gssbuf, gssbuf2;
	u_int len;

	mic.value = packet_get_string(&len);
	mic.length = len;

	packet_check_eom();

	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
	    "gssapi-keyex");

	gssbuf.value = buffer_ptr(&b);
	gssbuf.length = buffer_len(&b);

	/* client may have used empty username to determine target
	   name from GSSAPI context */
	ssh_gssapi_buildmic(&b2, "", authctxt->service, "gssapi-keyex");

	gssbuf2.value = buffer_ptr(&b2);
	gssbuf2.length = buffer_len(&b2);

	/* gss_kex_context is NULL with privsep, so we can't check it here */
	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context, 
						   &gssbuf, &mic))) ||
	    !GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context, 
						   &gssbuf2, &mic)))) {
	    if (authctxt->valid && authctxt->user && authctxt->user[0]) {
		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	    }
	}
	
	buffer_free(&b);
	buffer_free(&b2);
	xfree(mic.value);

	return (authenticated);
}

/*
 * 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 goid = {0, NULL};
	Gssctxt *ctxt = NULL;
	int mechs;
	gss_OID_set supported;
	int present;
	OM_uint32 ms;
	u_int len;
	u_char *doid = NULL;

	/* authctxt->valid may be 0 if we haven't yet determined
	   username from gssapi context. */

	if (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);

		present = 0;
		doid = packet_get_string(&len);

		if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
		    doid[1] == len - 2) {
			goid.elements = doid + 2;
			goid.length   = len - 2;
			gss_test_oid_set_member(&ms, &goid, supported,
			    &present);
		} else {
			logit("Badly formed OID received");
		}
	} while (mechs > 0 && !present);

	gss_release_oid_set(&ms, &supported);

	if (!present) {
		xfree(doid);
		authctxt->server_caused_failure = 1;
		return (0);
	}

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
		if (ctxt != NULL)
			ssh_gssapi_delete_ctx(&ctxt);
		xfree(doid);
		authctxt->server_caused_failure = 1;
		return (0);
	}

	authctxt->methoddata = (void *)ctxt;

	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

	/* Return the OID that we received */
	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, flags=0;
	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, &flags));

	xfree(recv_tok.value);

	if (GSS_ERROR(maj_status)) {
        	ssh_gssapi_userauth_error(gssctxt);
		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_with_mic ? "gssapi-with-mic" :
				                  "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);
			if (flags & GSS_C_INTEG_FLAG && gssapi_with_mic)
				dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
				    &input_gssapi_mic);
			else
				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);
}

static void
gssapi_set_implicit_username(Authctxt *authctxt)
{
    if ((authctxt->user == NULL) || (authctxt->user[0] == '\0')) {
	char *lname = NULL;
	PRIVSEP(ssh_gssapi_localname(&lname));
	if (lname && lname[0] != '\0') {
	    if (authctxt->user) xfree(authctxt->user);
	    authctxt->user = lname;
	    debug("set username to %s from gssapi context", lname);
	    authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
	    if (authctxt->pw) {
		authctxt->valid = 1;
	    }
	} else {
	    debug("failed to set username from gssapi context");
	    packet_send_debug("failed to set username from gssapi context");
	}
    }
    if (authctxt->pw) {
#ifdef USE_PAM
	if (options.use_pam)
		PRIVSEP(start_pam(authctxt));
#endif
    }
}

/*
 * 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");

	gssapi_set_implicit_username(authctxt);

	gssctxt = authctxt->methoddata;

	/*
	 * We don't need to check the status, because we're only enabled in
	 * the dispatcher once the exchange is complete
	 */

	packet_check_eom();

	/* user should be set if valid but we double-check here */
	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
	    authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	} else {
	    authenticated = 0;
	}

	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_MIC, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated,
			gssapi_with_mic ? "gssapi-with-mic" : "gssapi");
}

static int
userauth_gssapi_with_mic(Authctxt *authctxt)
{
    gssapi_with_mic = 1;
    return userauth_gssapi(authctxt);
}

static int
userauth_gssapi_without_mic(Authctxt *authctxt)
{
    gssapi_with_mic = 0;
    return userauth_gssapi(authctxt);
}

static void
input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	int authenticated = 0;
	Buffer b;
	gss_buffer_desc mic, gssbuf;
	u_int len;

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

	gssapi_set_implicit_username(authctxt);

	gssctxt = authctxt->methoddata;

	mic.value = packet_get_string(&len);
	mic.length = len;

	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
	    "gssapi-with-mic");

	gssbuf.value = buffer_ptr(&b);
	gssbuf.length = buffer_len(&b);

	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
	    if (authctxt->valid && authctxt->user && authctxt->user[0]) {
		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	    } else {
		authenticated = 0;
	    }
	else
		logit("GSSAPI MIC check failed");

	buffer_free(&b);
	xfree(mic.value);

	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_MIC, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
}

static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
	char *errstr;
	OM_uint32 maj,min;
	
	errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
	if (errstr) {
		packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
		packet_put_int(maj);
		packet_put_int(min);
		packet_put_cstring(errstr);
		packet_put_cstring("");
		packet_send();
		packet_write_wait();
		xfree(errstr);
	}
}

Authmethod method_external = {
	"external-keyx",
	userauth_external,
	&options.gss_authentication
};
	
Authmethod method_gsskeyex = {
	"gssapi-keyex",
	userauth_gsskeyex,
	&options.gss_authentication
};

Authmethod method_gssapi = {
	"gssapi-with-mic",
	userauth_gssapi_with_mic,
	&options.gss_authentication
};

Authmethod method_gssapi_compat = {
	"gssapi",
	userauth_gssapi_without_mic,
	&options.gss_authentication
};

#endif /* GSSAPI */
Commit	Line	Data
30460aeb	1	/* $OpenBSD: auth2-gss.c,v 1.15 2006/08/03 03:34:41 deraadt Exp $ */
7cac2b65	2
b59afbfe	3	/*
23987cb8	4	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
b59afbfe	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	*
	15	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
	16	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	17	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	18	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	19	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	20	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	24	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26
	27	#include "includes.h"
	28
	29	#ifdef GSSAPI
7cac2b65	30
30460aeb	31	#include <sys/types.h>
	32
	33	#include <stdarg.h>
	34
	35	#include "xmalloc.h"
	36	#include "key.h"
	37	#include "hostfile.h"
b59afbfe	38	#include "auth.h"
b59afbfe	39	#include "ssh2.h"
b59afbfe	40	#include "log.h"
b59afbfe	41	#include "dispatch.h"
30460aeb	42	#include "buffer.h"
b59afbfe	43	#include "servconf.h"
b59afbfe	44	#include "packet.h"
b59afbfe	45	#include "ssh-gss.h"
30460aeb	46	#include "monitor_wrap.h"
b59afbfe	47
b59afbfe	48	extern ServerOptions options;
b59afbfe	49
23987cb8	50	static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
b59afbfe	51	static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
540d72c3	52	static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
b59afbfe	53	static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
e23e524c	54	static void input_gssapi_errtok(int, u_int32_t, void *);
b59afbfe	55
540d72c3	56	static int gssapi_with_mic = 1; /* flag to toggle "gssapi-with-mic" vs.
	57	"gssapi" */
	58
5217e987	59	static int
	60	userauth_external(Authctxt *authctxt)
	61	{
	62	packet_check_eom();
	63
7a8e5702	64	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
294206af	65	return(PRIVSEP(ssh_gssapi_userok(authctxt->user)));
5217e987	66	}
	67	return 0;
	68	}
	69
fe4ad273	70	/*
	71	* The 'gssapi_keyex' userauth mechanism.
	72	*/
	73	static int
	74	userauth_gsskeyex(Authctxt *authctxt)
	75	{
	76	int authenticated = 0;
	77	Buffer b, b2;
	78	gss_buffer_desc mic, gssbuf, gssbuf2;
	79	u_int len;
	80
	81	mic.value = packet_get_string(&len);
	82	mic.length = len;
	83
	84	packet_check_eom();
	85
	86	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
	87	"gssapi-keyex");
	88
	89	gssbuf.value = buffer_ptr(&b);
	90	gssbuf.length = buffer_len(&b);
	91
	92	/* client may have used empty username to determine target
	93	name from GSSAPI context */
	94	ssh_gssapi_buildmic(&b2, "", authctxt->service, "gssapi-keyex");
	95
	96	gssbuf2.value = buffer_ptr(&b2);
	97	gssbuf2.length = buffer_len(&b2);
	98
	99	/* gss_kex_context is NULL with privsep, so we can't check it here */
	100	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
	101	&gssbuf, &mic))) \|\|
	102	!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
	103	&gssbuf2, &mic)))) {
	104	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
	105	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	106	}
	107	}
	108
	109	buffer_free(&b);
	110	buffer_free(&b2);
	111	xfree(mic.value);
	112
	113	return (authenticated);
	114	}
	115
7cac2b65	116	/*
7cac2b65	117	* We only support those mechanisms that we know about (ie ones that we know
08822d99	118	* how to check local user kuserok and the like)
b59afbfe	119	*/
	120	static int
	121	userauth_gssapi(Authctxt *authctxt)
	122	{
7e82606e	123	gss_OID_desc goid = {0, NULL};
7cac2b65	124	Gssctxt *ctxt = NULL;
	125	int mechs;
	126	gss_OID_set supported;
	127	int present;
	128	OM_uint32 ms;
	129	u_int len;
2ce0bfe4	130	u_char *doid = NULL;
7cac2b65	131
941f3f29	132	/* authctxt->valid may be 0 if we haven't yet determined
	133	username from gssapi context. */
	134
5217e987	135	if (authctxt->user == NULL)
7cac2b65	136	return (0);
	137
	138	mechs = packet_get_int();
	139	if (mechs == 0) {
	140	debug("Mechanism negotiation is not supported");
	141	return (0);
	142	}
	143
	144	ssh_gssapi_supported_oids(&supported);
	145	do {
	146	mechs--;
	147
	148	if (doid)
	149	xfree(doid);
	150
540d72c3	151	present = 0;
7cac2b65	152	doid = packet_get_string(&len);
7cac2b65	153
2ce0bfe4	154	if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
2ce0bfe4	155	doid[1] == len - 2) {
7e82606e	156	goid.elements = doid + 2;
7e82606e	157	goid.length = len - 2;
6fc2ad02	158	gss_test_oid_set_member(&ms, &goid, supported,
	159	&present);
	160	} else {
	161	logit("Badly formed OID received");
7cac2b65	162	}
7cac2b65	163	} while (mechs > 0 && !present);
	164
	165	gss_release_oid_set(&ms, &supported);
	166
	167	if (!present) {
	168	xfree(doid);
fe4ad273	169	authctxt->server_caused_failure = 1;
7cac2b65	170	return (0);
	171	}
	172
7e82606e	173	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
30460aeb	174	if (ctxt != NULL)
30460aeb	175	ssh_gssapi_delete_ctx(&ctxt);
7cac2b65	176	xfree(doid);
fe4ad273	177	authctxt->server_caused_failure = 1;
7cac2b65	178	return (0);
23987cb8	179	}
b59afbfe	180
08822d99	181	authctxt->methoddata = (void *)ctxt;
b59afbfe	182
7cac2b65	183	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
23987cb8	184
540d72c3	185	/* Return the OID that we received */
7cac2b65	186	packet_put_string(doid, len);
23987cb8	187
7cac2b65	188	packet_send();
7cac2b65	189	xfree(doid);
b59afbfe	190
7cac2b65	191	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
	192	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
	193	authctxt->postponed = 1;
	194
	195	return (0);
b59afbfe	196	}
	197
	198	static void
	199	input_gssapi_token(int type, u_int32_t plen, void *ctxt)
	200	{
7cac2b65	201	Authctxt *authctxt = ctxt;
	202	Gssctxt *gssctxt;
	203	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	204	gss_buffer_desc recv_tok;
147c00cc	205	OM_uint32 maj_status, min_status, flags=0;
7cac2b65	206	u_int len;
	207
	208	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	209	fatal("No authentication or GSSAPI context");
	210
	211	gssctxt = authctxt->methoddata;
	212	recv_tok.value = packet_get_string(&len);
	213	recv_tok.length = len; /* u_int vs. size_t */
	214
	215	packet_check_eom();
	216
	217	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
540d72c3	218	&send_tok, &flags));
7cac2b65	219
	220	xfree(recv_tok.value);
	221
	222	if (GSS_ERROR(maj_status)) {
e23e524c	223	ssh_gssapi_userauth_error(gssctxt);
e23e524c	224	if (send_tok.length != 0) {
e23e524c	225	packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
7cac2b65	226	packet_put_string(send_tok.value, send_tok.length);
	227	packet_send();
	228	}
	229	authctxt->postponed = 0;
7cac2b65	230	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
540d72c3	231	userauth_finish(authctxt, 0,
	232	gssapi_with_mic ? "gssapi-with-mic" :
	233	"gssapi");
7cac2b65	234	} else {
7cac2b65	235	if (send_tok.length != 0) {
7cac2b65	236	packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
	237	packet_put_string(send_tok.value, send_tok.length);
	238	packet_send();
	239	}
	240	if (maj_status == GSS_S_COMPLETE) {
7cac2b65	241	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
540d72c3	242	if (flags & GSS_C_INTEG_FLAG && gssapi_with_mic)
	243	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
	244	&input_gssapi_mic);
	245	else
	246	dispatch_set(
	247	SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
	248	&input_gssapi_exchange_complete);
7cac2b65	249	}
	250	}
	251
	252	gss_release_buffer(&min_status, &send_tok);
e23e524c	253	}
23987cb8	254
e23e524c	255	static void
	256	input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
	257	{
7cac2b65	258	Authctxt *authctxt = ctxt;
	259	Gssctxt *gssctxt;
	260	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	261	gss_buffer_desc recv_tok;
	262	OM_uint32 maj_status;
	263	u_int len;
	264
	265	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	266	fatal("No authentication or GSSAPI context");
	267
	268	gssctxt = authctxt->methoddata;
	269	recv_tok.value = packet_get_string(&len);
	270	recv_tok.length = len;
	271
	272	packet_check_eom();
	273
	274	/* Push the error token into GSSAPI to see what it says */
	275	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	276	&send_tok, NULL));
	277
	278	xfree(recv_tok.value);
e23e524c	279
e23e524c	280	/* We can't return anything to the client, even if we wanted to */
e23e524c	281	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
7cac2b65	282	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
e23e524c	283
e23e524c	284	/* The client will have already moved on to the next auth */
7cac2b65	285
7cac2b65	286	gss_release_buffer(&maj_status, &send_tok);
b59afbfe	287	}
b59afbfe	288
540d72c3	289	static void
	290	gssapi_set_implicit_username(Authctxt *authctxt)
	291	{
4f1e213f	292	if ((authctxt->user == NULL) \|\| (authctxt->user[0] == '\0')) {
540d72c3	293	char *lname = NULL;
	294	PRIVSEP(ssh_gssapi_localname(&lname));
	295	if (lname && lname[0] != '\0') {
4f1e213f	296	if (authctxt->user) xfree(authctxt->user);
540d72c3	297	authctxt->user = lname;
	298	debug("set username to %s from gssapi context", lname);
	299	authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
5217e987	300	if (authctxt->pw) {
	301	authctxt->valid = 1;
	302	}
540d72c3	303	} else {
540d72c3	304	debug("failed to set username from gssapi context");
d9e17760	305	packet_send_debug("failed to set username from gssapi context");
540d72c3	306	}
	307	}
	308	if (authctxt->pw) {
	309	#ifdef USE_PAM
147c00cc	310	if (options.use_pam)
5217e987	311	PRIVSEP(start_pam(authctxt));
540d72c3	312	#endif
	313	}
	314	}
	315
7cac2b65	316	/*
7cac2b65	317	* This is called when the client thinks we've completed authentication.
b59afbfe	318	* It should only be enabled in the dispatch handler by the function above,
	319	* which only enables it once the GSSAPI exchange is complete.
	320	*/
7cac2b65	321
b59afbfe	322	static void
	323	input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
	324	{
7cac2b65	325	Authctxt *authctxt = ctxt;
	326	Gssctxt *gssctxt;
	327	int authenticated;
	328
b59afbfe	329	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
7cac2b65	330	fatal("No authentication or GSSAPI context");
7cac2b65	331
540d72c3	332	gssapi_set_implicit_username(authctxt);
d13dfff4	333
7cac2b65	334	gssctxt = authctxt->methoddata;
7cac2b65	335
7cac2b65	336	/*
540d72c3	337	* We don't need to check the status, because we're only enabled in
540d72c3	338	* the dispatcher once the exchange is complete
b59afbfe	339	*/
b59afbfe	340
7cac2b65	341	packet_check_eom();
7cac2b65	342
941f3f29	343	/* user should be set if valid but we double-check here */
941f3f29	344	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
540d72c3	345	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	346	} else {
	347	authenticated = 0;
	348	}
b59afbfe	349
7cac2b65	350	authctxt->postponed = 0;
	351	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	352	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
540d72c3	353	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
7cac2b65	354	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
540d72c3	355	userauth_finish(authctxt, authenticated,
	356	gssapi_with_mic ? "gssapi-with-mic" : "gssapi");
	357	}
	358
	359	static int
	360	userauth_gssapi_with_mic(Authctxt *authctxt)
	361	{
	362	gssapi_with_mic = 1;
	363	return userauth_gssapi(authctxt);
	364	}
	365
	366	static int
	367	userauth_gssapi_without_mic(Authctxt *authctxt)
	368	{
	369	gssapi_with_mic = 0;
	370	return userauth_gssapi(authctxt);
	371	}
	372
	373	static void
	374	input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
	375	{
	376	Authctxt *authctxt = ctxt;
	377	Gssctxt *gssctxt;
	378	int authenticated = 0;
	379	Buffer b;
	380	gss_buffer_desc mic, gssbuf;
	381	u_int len;
	382
	383	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	384	fatal("No authentication or GSSAPI context");
	385
	386	gssapi_set_implicit_username(authctxt);
	387
	388	gssctxt = authctxt->methoddata;
	389
	390	mic.value = packet_get_string(&len);
	391	mic.length = len;
	392
	393	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
	394	"gssapi-with-mic");
	395
	396	gssbuf.value = buffer_ptr(&b);
	397	gssbuf.length = buffer_len(&b);
	398
	399	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
941f3f29	400	if (authctxt->valid && authctxt->user && authctxt->user[0]) {
540d72c3	401	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	402	} else {
	403	authenticated = 0;
	404	}
	405	else
	406	logit("GSSAPI MIC check failed");
	407
	408	buffer_free(&b);
	409	xfree(mic.value);
	410
	411	authctxt->postponed = 0;
	412	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	413	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
	414	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
	415	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	416	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
b59afbfe	417	}
b59afbfe	418
23987cb8	419	static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
	420	char *errstr;
	421	OM_uint32 maj,min;
	422
	423	errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
	424	if (errstr) {
	425	packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
	426	packet_put_int(maj);
	427	packet_put_int(min);
	428	packet_put_cstring(errstr);
	429	packet_put_cstring("");
	430	packet_send();
	431	packet_write_wait();
	432	xfree(errstr);
	433	}
	434	}
	435
b59afbfe	436	Authmethod method_external = {
	437	"external-keyx",
	438	userauth_external,
	439	&options.gss_authentication
	440	};
	441
fe4ad273	442	Authmethod method_gsskeyex = {
	443	"gssapi-keyex",
	444	userauth_gsskeyex,
	445	&options.gss_authentication
	446	};
	447
b59afbfe	448	Authmethod method_gssapi = {
540d72c3	449	"gssapi-with-mic",
	450	userauth_gssapi_with_mic,
	451	&options.gss_authentication
	452	};
	453
	454	Authmethod method_gssapi_compat = {
7cac2b65	455	"gssapi",
540d72c3	456	userauth_gssapi_without_mic,
7cac2b65	457	&options.gss_authentication
b59afbfe	458	};
	459
	460	#endif /* GSSAPI */