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/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */

/*

 * Copyright (c) 2001-2007 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

#ifdef KRB5

#include <sys/types.h>

#include <stdarg.h>

#include <string.h>

#include "xmalloc.h"

#include "key.h"

#include "hostfile.h"

#include "auth.h"

#include "log.h"

#include "servconf.h"

#include "buffer.h"

#include "ssh-gss.h"

extern ServerOptions options;

#ifdef HEIMDAL

# include <krb5.h>

#else

# ifdef HAVE_GSSAPI_KRB5_H

#  include <gssapi_krb5.h>

# elif HAVE_GSSAPI_GSSAPI_KRB5_H

#  include <gssapi/gssapi_krb5.h>

# endif

#endif

static krb5_context krb_context = NULL;

/* Initialise the krb5 library, for the stuff that GSSAPI won't do */

static int

ssh_gssapi_krb5_init(void)

{

	krb5_error_code problem;

	if (krb_context != NULL)

		return 1;

	problem = krb5_init_context(&krb_context);

	if (problem) {

		logit("Cannot initialize krb5 context");

		return 0;

	}

	return 1;

}

/* Check if this user is OK to login. This only works with krb5 - other

 * GSSAPI mechanisms will need their own.

 * Returns true if the user is OK to log in, otherwise returns 0

 */

static int

ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)

{

	krb5_principal princ;

	int retval;

	if (ssh_gssapi_krb5_init() == 0)

		return 0;

	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,

	    &princ))) {

		logit("krb5_parse_name(): %.100s",

		    krb5_get_err_text(krb_context, retval));

		return 0;

	}

	if (krb5_kuserok(krb_context, princ, name)) {

		retval = 1;

		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",

		    name, (char *)client->displayname.value);

	} else

		retval = 0;

	krb5_free_principal(krb_context, princ);

	return retval;

}

/* This writes out any forwarded credentials from the structure populated

 * during userauth. Called after we have setuid to the user */

static void

ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)

{

	krb5_ccache ccache;

	krb5_error_code problem;

	krb5_principal princ;

	OM_uint32 maj_status, min_status;

	int len;

	const char *new_ccname;

	if (client->creds == NULL) {

		debug("No credentials stored");

		return;

	}

	if (ssh_gssapi_krb5_init() == 0)

		return;

#ifdef HEIMDAL

	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {

		logit("krb5_cc_gen_new(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		return;

	}

#else

	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {

		logit("ssh_krb5_cc_gen(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		return;

	}

#endif	/* #ifdef HEIMDAL */

	if ((problem = krb5_parse_name(krb_context,

	    client->exportedname.value, &princ))) {

		logit("krb5_parse_name(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		krb5_cc_destroy(krb_context, ccache);

		return;

	}

	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {

		logit("krb5_cc_initialize(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		krb5_free_principal(krb_context, princ);

		krb5_cc_destroy(krb_context, ccache);

		return;

	}

	krb5_free_principal(krb_context, princ);

	if ((maj_status = gss_krb5_copy_ccache(&min_status,

	    client->creds, ccache))) {

		logit("gss_krb5_copy_ccache() failed");

		krb5_cc_destroy(krb_context, ccache);

		return;

	}

	new_ccname = krb5_cc_get_name(krb_context, ccache);

	client->store.envvar = "KRB5CCNAME";

#ifdef USE_CCAPI

	xasprintf(&client->store.envval, "API:%s", new_ccname);

	client->store.filename = NULL;

#else

	xasprintf(&client->store.envval, "FILE:%s", new_ccname);

	client->store.filename = xstrdup(new_ccname);

#endif

#ifdef USE_PAM

	if (options.use_pam)

		do_pam_putenv(client->store.envvar, client->store.envval);

#endif

	krb5_cc_close(krb_context, ccache);

	return;

}

int

ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, 

    ssh_gssapi_client *client)

{

	krb5_ccache ccache = NULL;

	krb5_principal principal = NULL;

	char *name = NULL;

	krb5_error_code problem;

	OM_uint32 maj_status, min_status;

   	if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {

                logit("krb5_cc_resolve(): %.100s",

                    krb5_get_err_text(krb_context, problem));

                return 0;

       	}

	/* Find out who the principal in this cache is */

	if ((problem = krb5_cc_get_principal(krb_context, ccache, 

	    &principal))) {

		logit("krb5_cc_get_principal(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		krb5_cc_close(krb_context, ccache);

		return 0;

	}

	if ((problem = krb5_unparse_name(krb_context, principal, &name))) {

		logit("krb5_unparse_name(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		krb5_free_principal(krb_context, principal);

		krb5_cc_close(krb_context, ccache);

		return 0;

	}

	if (strcmp(name,client->exportedname.value)!=0) {

		debug("Name in local credentials cache differs. Not storing");

		krb5_free_principal(krb_context, principal);

		krb5_cc_close(krb_context, ccache);

		krb5_free_unparsed_name(krb_context, name);

		return 0;

	}

	krb5_free_unparsed_name(krb_context, name);

	/* Name matches, so lets get on with it! */

	if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {

		logit("krb5_cc_initialize(): %.100s",

		    krb5_get_err_text(krb_context, problem));

		krb5_free_principal(krb_context, principal);

		krb5_cc_close(krb_context, ccache);

		return 0;

	}

	krb5_free_principal(krb_context, principal);

	if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,

	    ccache))) {

		logit("gss_krb5_copy_ccache() failed. Sorry!");

		krb5_cc_close(krb_context, ccache);

		return 0;

	}

	return 1;

}

ssh_gssapi_mech gssapi_kerberos_mech = {

	"toWM5Slw5Ew8Mqkay+al2g==",

	"Kerberos",

	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},

	NULL,

	&ssh_gssapi_krb5_userok,

	NULL,

	&ssh_gssapi_krb5_storecreds,

	&ssh_gssapi_krb5_updatecreds

};

#endif /* KRB5 */

#endif /* GSSAPI */