524.c

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/*
 * Copyright (c) 1997-2005 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * 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. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 "kdc_locl.h"

RCSID("$Id: 524.c 18270 2006-10-06 17:06:30Z lha $");

#include <krb5-v4compat.h>

/*
 * fetch the server from `t', returning the name in malloced memory in
 * `spn' and the entry itself in `server'
 */

static krb5_error_code
fetch_server (krb5_context context, 
	      krb5_kdc_configuration *config,
	      const Ticket *t,
	      char **spn,
	      hdb_entry_ex **server,
	      const char *from)
{
    krb5_error_code ret;
    krb5_principal sprinc;

    ret = _krb5_principalname2krb5_principal(context, &sprinc,
					     t->sname, t->realm);
    if (ret) {
	kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
		krb5_get_err_text(context, ret));
	return ret;
    }
    ret = krb5_unparse_name(context, sprinc, spn);
    if (ret) {
	krb5_free_principal(context, sprinc);
	kdc_log(context, config, 0, "krb5_unparse_name: %s",
		krb5_get_err_text(context, ret));
	return ret;
    }
    ret = _kdc_db_fetch(context, config, sprinc, HDB_F_GET_SERVER, 
			NULL, server);
    krb5_free_principal(context, sprinc);
    if (ret) {
	kdc_log(context, config, 0,
	"Request to convert ticket from %s for unknown principal %s: %s",
		from, *spn, krb5_get_err_text(context, ret));
	if (ret == HDB_ERR_NOENTRY)
	    ret = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
	return ret;
    }
    return 0;
}

static krb5_error_code
log_524 (krb5_context context, 
	 krb5_kdc_configuration *config,
	 const EncTicketPart *et,
	 const char *from,
	 const char *spn)
{
    krb5_principal client;
    char *cpn;
    krb5_error_code ret;

    ret = _krb5_principalname2krb5_principal(context, &client, 
					     et->cname, et->crealm);
    if (ret) {
	kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
		krb5_get_err_text (context, ret));
	return ret;
    }
    ret = krb5_unparse_name(context, client, &cpn);
    if (ret) {
	krb5_free_principal(context, client);
	kdc_log(context, config, 0, "krb5_unparse_name: %s",
		krb5_get_err_text (context, ret));
	return ret;
    }
    kdc_log(context, config, 1, "524-REQ %s from %s for %s", cpn, from, spn);
    free(cpn);
    krb5_free_principal(context, client);
    return 0;
}

static krb5_error_code
verify_flags (krb5_context context, 
	      krb5_kdc_configuration *config,
	      const EncTicketPart *et,
	      const char *spn)
{
    if(et->endtime < kdc_time){
	kdc_log(context, config, 0, "Ticket expired (%s)", spn);
	return KRB5KRB_AP_ERR_TKT_EXPIRED;
    }
    if(et->flags.invalid){
	kdc_log(context, config, 0, "Ticket not valid (%s)", spn);
	return KRB5KRB_AP_ERR_TKT_NYV;
    }
    return 0;
}

/*
 * set the `et->caddr' to the most appropriate address to use, where
 * `addr' is the address the request was received from.
 */

static krb5_error_code
set_address (krb5_context context, 
	     krb5_kdc_configuration *config,
	     EncTicketPart *et,
	     struct sockaddr *addr,
	     const char *from)
{
    krb5_error_code ret;
    krb5_address *v4_addr;

    v4_addr = malloc (sizeof(*v4_addr));
    if (v4_addr == NULL)
	return ENOMEM;

    ret = krb5_sockaddr2address(context, addr, v4_addr);
    if(ret) {
	free (v4_addr);
	kdc_log(context, config, 0, "Failed to convert address (%s)", from);
	return ret;
    }
	    
    if (et->caddr && !krb5_address_search (context, v4_addr, et->caddr)) {
	kdc_log(context, config, 0, "Incorrect network address (%s)", from);
	krb5_free_address(context, v4_addr);
	free (v4_addr);
	return KRB5KRB_AP_ERR_BADADDR;
    }
    if(v4_addr->addr_type == KRB5_ADDRESS_INET) {
	/* we need to collapse the addresses in the ticket to a
	   single address; best guess is to use the address the
	   connection came from */
	
	if (et->caddr != NULL) {
	    free_HostAddresses(et->caddr);
	} else {
	    et->caddr = malloc (sizeof (*et->caddr));
	    if (et->caddr == NULL) {
		krb5_free_address(context, v4_addr);
		free(v4_addr);
		return ENOMEM;
	    }
	}
	et->caddr->val = v4_addr;
	et->caddr->len = 1;
    } else {
	krb5_free_address(context, v4_addr);
	free(v4_addr);
    }
    return 0;
}


static krb5_error_code
encrypt_v4_ticket(krb5_context context, 
		  krb5_kdc_configuration *config,
		  void *buf, 
		  size_t len, 
		  krb5_keyblock *skey, 
		  EncryptedData *reply)
{
    krb5_crypto crypto;
    krb5_error_code ret;
    ret = krb5_crypto_init(context, skey, ETYPE_DES_PCBC_NONE, &crypto);
    if (ret) {
	free(buf);
	kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
		krb5_get_err_text(context, ret));
	return ret;
    }

    ret = krb5_encrypt_EncryptedData(context, 
				     crypto,
				     KRB5_KU_TICKET,
				     buf,
				     len,
				     0,
				     reply);
    krb5_crypto_destroy(context, crypto);
    if(ret) {
	kdc_log(context, config, 0, "Failed to encrypt data: %s",
		krb5_get_err_text(context, ret));
	return ret;
    }
    return 0;
}

static krb5_error_code
encode_524_response(krb5_context context, 
		    krb5_kdc_configuration *config,
		    const char *spn, const EncTicketPart et,
		    const Ticket *t, hdb_entry_ex *server, 
		    EncryptedData *ticket, int *kvno)
{
    krb5_error_code ret;
    int use_2b;
    size_t len;

    use_2b = krb5_config_get_bool(context, NULL, "kdc", "use_2b", spn, NULL);
    if(use_2b) {
	ASN1_MALLOC_ENCODE(EncryptedData, 
			   ticket->cipher.data, ticket->cipher.length, 
			   &t->enc_part, &len, ret);
	
	if (ret) {
	    kdc_log(context, config, 0, 
		    "Failed to encode v4 (2b) ticket (%s)", spn);
	    return ret;
	}
	
	ticket->etype = 0;
	ticket->kvno = NULL;
	*kvno = 213; /* 2b's use this magic kvno */
    } else {
	unsigned char buf[MAX_KTXT_LEN + 4 * 4];
	Key *skey;
	
	if (!config->enable_v4_cross_realm && strcmp (et.crealm, t->realm) != 0) {
	    kdc_log(context, config, 0, "524 cross-realm %s -> %s disabled", et.crealm,
		    t->realm);
	    return KRB5KDC_ERR_POLICY;
	}

	ret = _kdc_encode_v4_ticket(context, config, 
				    buf + sizeof(buf) - 1, sizeof(buf),
				    &et, &t->sname, &len);
	if(ret){
	    kdc_log(context, config, 0,
		    "Failed to encode v4 ticket (%s)", spn);
	    return ret;
	}
	ret = _kdc_get_des_key(context, server, TRUE, FALSE, &skey);
	if(ret){
	    kdc_log(context, config, 0,
		    "no suitable DES key for server (%s)", spn);
	    return ret;
	}
	ret = encrypt_v4_ticket(context, config, buf + sizeof(buf) - len, len, 
				&skey->key, ticket);
	if(ret){
	    kdc_log(context, config, 0,
		    "Failed to encrypt v4 ticket (%s)", spn);
	    return ret;
	}
	*kvno = server->entry.kvno;
    }

    return 0;
}

/*
 * process a 5->4 request, based on `t', and received `from, addr',
 * returning the reply in `reply'
 */

krb5_error_code
_kdc_do_524(krb5_context context, 
	    krb5_kdc_configuration *config,
	    const Ticket *t, krb5_data *reply,
	    const char *from, struct sockaddr *addr)
{
    krb5_error_code ret = 0;
    krb5_crypto crypto;
    hdb_entry_ex *server = NULL;
    Key *skey;
    krb5_data et_data;
    EncTicketPart et;
    EncryptedData ticket;
    krb5_storage *sp;
    char *spn = NULL;
    unsigned char buf[MAX_KTXT_LEN + 4 * 4];
    size_t len;
    int kvno = 0;
    
    if(!config->enable_524) {
	ret = KRB5KDC_ERR_POLICY;
	kdc_log(context, config, 0,
		"Rejected ticket conversion request from %s", from);
	goto out;
    }

    ret = fetch_server (context, config, t, &spn, &server, from);
    if (ret) {
	goto out;
    }

    ret = hdb_enctype2key(context, &server->entry, t->enc_part.etype, &skey);
    if(ret){
	kdc_log(context, config, 0,
		"No suitable key found for server (%s) from %s", spn, from);
	goto out;
    }
    ret = krb5_crypto_init(context, &skey->key, 0, &crypto);
    if (ret) {
	kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
		krb5_get_err_text(context, ret));
	goto out;
    }
    ret = krb5_decrypt_EncryptedData (context,
				      crypto,
				      KRB5_KU_TICKET,
				      &t->enc_part,
				      &et_data);
    krb5_crypto_destroy(context, crypto);
    if(ret){
	kdc_log(context, config, 0,
		"Failed to decrypt ticket from %s for %s", from, spn);
	goto out;
    }
    ret = krb5_decode_EncTicketPart(context, et_data.data, et_data.length, 
				    &et, &len);
    krb5_data_free(&et_data);
    if(ret){
	kdc_log(context, config, 0,
		"Failed to decode ticket from %s for %s", from, spn);
	goto out;
    }

    ret = log_524 (context, config, &et, from, spn);
    if (ret) {
	free_EncTicketPart(&et);
	goto out;
    }

    ret = verify_flags (context, config, &et, spn);
    if (ret) {
	free_EncTicketPart(&et);
	goto out;
    }

    ret = set_address (context, config, &et, addr, from);
    if (ret) {
	free_EncTicketPart(&et);
	goto out;
    }

    ret = encode_524_response(context, config, spn, et, t,
			      server, &ticket, &kvno);
    free_EncTicketPart(&et);

 out:
    /* make reply */
    memset(buf, 0, sizeof(buf));
    sp = krb5_storage_from_mem(buf, sizeof(buf));
    if (sp) {
	krb5_store_int32(sp, ret);
	if(ret == 0){
	    krb5_store_int32(sp, kvno);
	    krb5_store_data(sp, ticket.cipher);
	    /* Aargh! This is coded as a KTEXT_ST. */
	    krb5_storage_seek(sp, MAX_KTXT_LEN - ticket.cipher.length, SEEK_CUR);
	    krb5_store_int32(sp, 0); /* mbz */
	    free_EncryptedData(&ticket);
	}
	ret = krb5_storage_to_data(sp, reply);
	reply->length = krb5_storage_seek(sp, 0, SEEK_CUR);
	krb5_storage_free(sp);
    } else
	krb5_data_zero(reply);
    if(spn)
	free(spn);
    if(server)
	_kdc_free_ent (context, server);
    return ret;
}