mk_safe.c   [plain text]

/*
 * lib/krb5/krb/mk_safe.c
 *
 * Copyright 1990,1991 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 * 
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  Furthermore if you modify this software you must label
 * your software as modified software and not distribute it in such a
 * fashion that it might be confused with the original M.I.T. software.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 * 
 *
 * krb5_mk_safe()
 */

#include "k5-int.h"
#include "cleanup.h"
#include "auth_con.h"

/*
 Formats a KRB_SAFE message into outbuf.

 userdata is formatted as the user data in the message.
 sumtype specifies the encryption type; key specifies the key which
 might be used to seed the checksum; sender_addr and recv_addr specify
 the full addresses (host and port) of the sender and receiver.
 The host portion of sender_addr is used to form the addresses used in the
 KRB_SAFE message.

 The outbuf buffer storage is allocated, and should be freed by the
 caller when finished.

 returns system errors
*/
static krb5_error_code
krb5_mk_safe_basic(krb5_context context, const krb5_data *userdata,
		   const krb5_keyblock *keyblock, krb5_replay_data *replaydata,
		   krb5_address *local_addr, krb5_address *remote_addr,
		   krb5_cksumtype sumtype, krb5_data *outbuf)
{
    krb5_error_code retval;
    krb5_safe safemsg;
    krb5_octet zero_octet = 0;
    krb5_checksum safe_checksum;
    krb5_data *scratch1, *scratch2;

    if (!krb5_c_valid_cksumtype(sumtype))
	return KRB5_PROG_SUMTYPE_NOSUPP;
    if (!krb5_c_is_coll_proof_cksum(sumtype)
	|| !krb5_c_is_keyed_cksum(sumtype))
	return KRB5KRB_AP_ERR_INAPP_CKSUM;

    safemsg.user_data = *userdata;
    safemsg.s_address = (krb5_address *) local_addr;
    safemsg.r_address = (krb5_address *) remote_addr;

    /* We should check too make sure one exists. */
    safemsg.timestamp  = replaydata->timestamp;
    safemsg.usec       = replaydata->usec;
    safemsg.seq_number = replaydata->seq;

    /* 
     * To do the checksum stuff, we need to encode the message with a
     * zero-length zero-type checksum, then checksum the encoding, then
     * re-encode with the checksum. 
     */

    safe_checksum.length = 0;
    safe_checksum.checksum_type = 0;
    safe_checksum.contents = &zero_octet;

    safemsg.checksum = &safe_checksum;

    if ((retval = encode_krb5_safe(&safemsg, &scratch1)))
	return retval;

    if ((retval = krb5_c_make_checksum(context, sumtype, keyblock,
				       KRB5_KEYUSAGE_KRB_SAFE_CKSUM,
				       scratch1, &safe_checksum)))
	goto cleanup_checksum;

    safemsg.checksum = &safe_checksum;
    if ((retval = encode_krb5_safe(&safemsg, &scratch2))) {
	goto cleanup_checksum;
    }
    *outbuf = *scratch2;
    krb5_xfree(scratch2);
    retval = 0;

cleanup_checksum:
    krb5_xfree(safe_checksum.contents);

    memset((char *)scratch1->data, 0, scratch1->length); 
    krb5_free_data(context, scratch1);
    return retval;
}

krb5_error_code KRB5_CALLCONV
krb5_mk_safe(krb5_context context, krb5_auth_context auth_context, const krb5_data *userdata, krb5_data *outbuf, krb5_replay_data *outdata)
{
    krb5_error_code 	  retval;
    krb5_keyblock       * keyblock;
    krb5_replay_data      replaydata;

    /* Clear replaydata block */
    memset((char *) &replaydata, 0, sizeof(krb5_replay_data));

    /* Get keyblock */
    if ((keyblock = auth_context->send_subkey) == NULL)
	keyblock = auth_context->keyblock;

    /* Get replay info */
    if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_TIME) &&
      (auth_context->rcache == NULL))
	return KRB5_RC_REQUIRED;

    if (((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_TIME) ||
      (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE)) &&
      (outdata == NULL))
	/* Need a better error */
	return KRB5_RC_REQUIRED;

    if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_TIME) ||
	(auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_TIME)) {
	if ((retval = krb5_us_timeofday(context, &replaydata.timestamp,
					&replaydata.usec)))
	    return retval;
	if (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_TIME) {
    	    outdata->timestamp = replaydata.timestamp;
    	    outdata->usec = replaydata.usec;
	}
    }
    if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) ||
	(auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE)) {
	replaydata.seq = auth_context->local_seq_number++;
	if (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE) {
    	    outdata->seq = replaydata.seq;
	}
    } 

{
    krb5_address * premote_fulladdr = NULL;
    krb5_address * plocal_fulladdr = NULL;
    krb5_address remote_fulladdr;
    krb5_address local_fulladdr;
    krb5_cksumtype sumtype;

    CLEANUP_INIT(2);

    if (auth_context->local_addr) {
    	if (auth_context->local_port) {
            if (!(retval = krb5_make_fulladdr(context, auth_context->local_addr,
                                 	      auth_context->local_port, 
					      &local_fulladdr))){
            	CLEANUP_PUSH(local_fulladdr.contents, free);
	    	plocal_fulladdr = &local_fulladdr;
            } else {
                goto error;
            }
	} else {
            plocal_fulladdr = auth_context->local_addr;
        }

    }

    if (auth_context->remote_addr) {
    	if (auth_context->remote_port) {
            if (!(retval = krb5_make_fulladdr(context,auth_context->remote_addr,
                                 	      auth_context->remote_port, 
					      &remote_fulladdr))){
            	CLEANUP_PUSH(remote_fulladdr.contents, free);
	    	premote_fulladdr = &remote_fulladdr;
            } else {
                CLEANUP_DONE();
                goto error;
            }
	} else {
            premote_fulladdr = auth_context->remote_addr;
        }
    }

    {
	unsigned int nsumtypes;
	unsigned int i;
	krb5_cksumtype *sumtypes;
	retval = krb5_c_keyed_checksum_types (context, keyblock->enctype,
					      &nsumtypes, &sumtypes);
	if (retval) {
	    CLEANUP_DONE ();
	    goto error;
	}
	if (nsumtypes == 0) {
		retval = KRB5_BAD_ENCTYPE;
		krb5_free_cksumtypes (context, sumtypes);
		CLEANUP_DONE ();
		goto error;
	}
	for (i = 0; i < nsumtypes; i++)
		if (auth_context->safe_cksumtype == sumtypes[i])
			break;
	if (i == nsumtypes)
		i = 0;
	sumtype = sumtypes[i];
	krb5_free_cksumtypes (context, sumtypes);
    }
    if ((retval = krb5_mk_safe_basic(context, userdata, keyblock, &replaydata, 
				     plocal_fulladdr, premote_fulladdr,
				     sumtype, outbuf))) {
	CLEANUP_DONE();
	goto error;
    }

    CLEANUP_DONE();
}

    if (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_TIME) {
	krb5_donot_replay replay;

	if ((retval = krb5_gen_replay_name(context, auth_context->local_addr, 
					   "_safe", &replay.client))) {
    	    krb5_xfree(outbuf);
	    goto error;
	}

	replay.server = "";		/* XXX */
	replay.cusec = replaydata.usec;
	replay.ctime = replaydata.timestamp;
	if ((retval = krb5_rc_store(context, auth_context->rcache, &replay))) {
	    /* should we really error out here? XXX */
    	    krb5_xfree(outbuf);
	    goto error;
	}
	krb5_xfree(replay.client);
    }

    return 0;

error:
    if ((auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) ||
      (auth_context->auth_context_flags & KRB5_AUTH_CONTEXT_RET_SEQUENCE)) 
	auth_context->local_seq_number--;

    return retval;
}