rd_cred.c

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/*
 * Copyright (c) 1997 - 2007 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 <krb5_locl.h>

RCSID("$Id: rd_cred.c 20304 2007-04-11 11:15:05Z lha $");

static krb5_error_code
compare_addrs(krb5_context context,
	      krb5_address *a,
	      krb5_address *b,
	      const char *message)
{
    char a_str[64], b_str[64];
    size_t len;

    if(krb5_address_compare (context, a, b))
	return 0;

    krb5_print_address (a, a_str, sizeof(a_str), &len);
    krb5_print_address (b, b_str, sizeof(b_str), &len);
    krb5_set_error_string(context, "%s: %s != %s", message, b_str, a_str);
    return KRB5KRB_AP_ERR_BADADDR;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_cred(krb5_context context,
	     krb5_auth_context auth_context,
	     krb5_data *in_data,
	     krb5_creds ***ret_creds,
	     krb5_replay_data *outdata)
{
    krb5_error_code ret;
    size_t len;
    KRB_CRED cred;
    EncKrbCredPart enc_krb_cred_part;
    krb5_data enc_krb_cred_part_data;
    krb5_crypto crypto;
    int i;

    memset(&enc_krb_cred_part, 0, sizeof(enc_krb_cred_part));

    if ((auth_context->flags & 
	 (KRB5_AUTH_CONTEXT_RET_TIME | KRB5_AUTH_CONTEXT_RET_SEQUENCE)) &&
	outdata == NULL)
	return KRB5_RC_REQUIRED; /* XXX better error, MIT returns this */

    *ret_creds = NULL;

    ret = decode_KRB_CRED(in_data->data, in_data->length, 
			  &cred, &len);
    if(ret) {
	krb5_clear_error_string(context);
	return ret;
    }

    if (cred.pvno != 5) {
	ret = KRB5KRB_AP_ERR_BADVERSION;
	krb5_clear_error_string (context);
	goto out;
    }

    if (cred.msg_type != krb_cred) {
	ret = KRB5KRB_AP_ERR_MSG_TYPE;
	krb5_clear_error_string (context);
	goto out;
    }

    if (cred.enc_part.etype == ETYPE_NULL) {  
	/* DK: MIT GSS-API Compatibility */
	enc_krb_cred_part_data.length = cred.enc_part.cipher.length;
	enc_krb_cred_part_data.data   = cred.enc_part.cipher.data;
    } else {
	/* Try both subkey and session key.
	 * 
	 * RFC4120 claims we should use the session key, but Heimdal
	 * before 0.8 used the remote subkey if it was send in the
	 * auth_context.
	 */

	if (auth_context->remote_subkey) {
	    ret = krb5_crypto_init(context, auth_context->remote_subkey,
				   0, &crypto);
	    if (ret)
		goto out;

	    ret = krb5_decrypt_EncryptedData(context,
					     crypto,
					     KRB5_KU_KRB_CRED,
					     &cred.enc_part,
					     &enc_krb_cred_part_data);
	    
	    krb5_crypto_destroy(context, crypto);
	}

	/* 
	 * If there was not subkey, or we failed using subkey, 
	 * retry using the session key
	 */
	if (auth_context->remote_subkey == NULL || ret == KRB5KRB_AP_ERR_BAD_INTEGRITY)
	{

	    ret = krb5_crypto_init(context, auth_context->keyblock,
				   0, &crypto);

	    if (ret)
		goto out;
	    
	    ret = krb5_decrypt_EncryptedData(context,
					     crypto,
					     KRB5_KU_KRB_CRED,
					     &cred.enc_part,
					     &enc_krb_cred_part_data);
	    
	    krb5_crypto_destroy(context, crypto);
	}
	if (ret)
	    goto out;
    }

    ret = krb5_decode_EncKrbCredPart (context,
				      enc_krb_cred_part_data.data,
				      enc_krb_cred_part_data.length,
				      &enc_krb_cred_part,
				      &len);
    if (enc_krb_cred_part_data.data != cred.enc_part.cipher.data)
	krb5_data_free(&enc_krb_cred_part_data);
    if (ret)
	goto out;

    /* check sender address */

    if (enc_krb_cred_part.s_address
	&& auth_context->remote_address
	&& auth_context->remote_port) {
	krb5_address *a;

	ret = krb5_make_addrport (context, &a,
				  auth_context->remote_address,
				  auth_context->remote_port);
	if (ret)
	    goto out;


	ret = compare_addrs(context, a, enc_krb_cred_part.s_address, 
			    "sender address is wrong in received creds");
	krb5_free_address(context, a);
	free(a);
	if(ret)
	    goto out;
    }

    /* check receiver address */

    if (enc_krb_cred_part.r_address
	&& auth_context->local_address) {
	if(auth_context->local_port &&
	   enc_krb_cred_part.r_address->addr_type == KRB5_ADDRESS_ADDRPORT) {
	    krb5_address *a;
	    ret = krb5_make_addrport (context, &a,
				      auth_context->local_address,
				      auth_context->local_port);
	    if (ret)
		goto out;
	    
	    ret = compare_addrs(context, a, enc_krb_cred_part.r_address, 
				"receiver address is wrong in received creds");
	    krb5_free_address(context, a);
	    free(a);
	    if(ret)
		goto out;
	} else {
	    ret = compare_addrs(context, auth_context->local_address,
				enc_krb_cred_part.r_address,
				"receiver address is wrong in received creds");
	    if(ret)
		goto out;
	}
    }

    /* check timestamp */
    if (auth_context->flags & KRB5_AUTH_CONTEXT_DO_TIME) {
	krb5_timestamp sec;

	krb5_timeofday (context, &sec);

	if (enc_krb_cred_part.timestamp == NULL ||
	    enc_krb_cred_part.usec      == NULL ||
	    abs(*enc_krb_cred_part.timestamp - sec)
	    > context->max_skew) {
	    krb5_clear_error_string (context);
	    ret = KRB5KRB_AP_ERR_SKEW;
	    goto out;
	}
    }

    if ((auth_context->flags & 
	 (KRB5_AUTH_CONTEXT_RET_TIME | KRB5_AUTH_CONTEXT_RET_SEQUENCE))) {
	/* if these fields are not present in the cred-part, silently
           return zero */
	memset(outdata, 0, sizeof(*outdata));
	if(enc_krb_cred_part.timestamp)
	    outdata->timestamp = *enc_krb_cred_part.timestamp;
	if(enc_krb_cred_part.usec)
	    outdata->usec = *enc_krb_cred_part.usec;
	if(enc_krb_cred_part.nonce)
	    outdata->seq = *enc_krb_cred_part.nonce;
    }
    
    /* Convert to NULL terminated list of creds */

    *ret_creds = calloc(enc_krb_cred_part.ticket_info.len + 1, 
			sizeof(**ret_creds));

    if (*ret_creds == NULL) {
	ret = ENOMEM;
	krb5_set_error_string (context, "malloc: out of memory");
	goto out;
    }

    for (i = 0; i < enc_krb_cred_part.ticket_info.len; ++i) {
	KrbCredInfo *kci = &enc_krb_cred_part.ticket_info.val[i];
	krb5_creds *creds;

	creds = calloc(1, sizeof(*creds));
	if(creds == NULL) {
	    ret = ENOMEM;
	    krb5_set_error_string (context, "malloc: out of memory");
	    goto out;
	}

	ASN1_MALLOC_ENCODE(Ticket, creds->ticket.data, creds->ticket.length, 
			   &cred.tickets.val[i], &len, ret);
	if (ret) {
	    free(creds);
	    goto out;
	}
	if(creds->ticket.length != len)
	    krb5_abortx(context, "internal error in ASN.1 encoder");
	copy_EncryptionKey (&kci->key, &creds->session);
	if (kci->prealm && kci->pname)
	    _krb5_principalname2krb5_principal (context,
						&creds->client,
						*kci->pname,
						*kci->prealm);
	if (kci->flags)
	    creds->flags.b = *kci->flags;
	if (kci->authtime)
	    creds->times.authtime = *kci->authtime;
	if (kci->starttime)
	    creds->times.starttime = *kci->starttime;
	if (kci->endtime)
	    creds->times.endtime = *kci->endtime;
	if (kci->renew_till)
	    creds->times.renew_till = *kci->renew_till;
	if (kci->srealm && kci->sname)
	    _krb5_principalname2krb5_principal (context,
						&creds->server,
						*kci->sname,
						*kci->srealm);
	if (kci->caddr)
	    krb5_copy_addresses (context,
				 kci->caddr,
				 &creds->addresses);
	
	(*ret_creds)[i] = creds;
	
    }
    (*ret_creds)[i] = NULL;

    free_KRB_CRED (&cred);
    free_EncKrbCredPart(&enc_krb_cred_part);

    return 0;

  out:
    free_EncKrbCredPart(&enc_krb_cred_part);
    free_KRB_CRED (&cred);
    if(*ret_creds) {
	for(i = 0; (*ret_creds)[i]; i++)
	    krb5_free_creds(context, (*ret_creds)[i]);
	free(*ret_creds);
	*ret_creds = NULL;
    }
    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_rd_cred2 (krb5_context      context,
	       krb5_auth_context auth_context,
	       krb5_ccache       ccache,
	       krb5_data         *in_data)
{
    krb5_error_code ret;
    krb5_creds **creds;
    int i;

    ret = krb5_rd_cred(context, auth_context, in_data, &creds, NULL);
    if(ret)
	return ret;

    /* Store the creds in the ccache */

    for(i = 0; creds && creds[i]; i++) {
	krb5_cc_store_cred(context, ccache, creds[i]);
	krb5_free_creds(context, creds[i]);
    }
    free(creds);
    return 0;
}