get_in_tkt.c

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/*
 * Copyright (c) 1997 - 2002 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: get_in_tkt.c 20226 2007-02-16 03:31:50Z lha $");

krb5_error_code KRB5_LIB_FUNCTION
krb5_init_etype (krb5_context context,
		 unsigned *len,
		 krb5_enctype **val,
		 const krb5_enctype *etypes)
{
    int i;
    krb5_error_code ret;
    krb5_enctype *tmp = NULL;

    ret = 0;
    if (etypes == NULL) {
	ret = krb5_get_default_in_tkt_etypes(context,
					     &tmp);
	if (ret)
	    return ret;
	etypes = tmp;
    }

    for (i = 0; etypes[i]; ++i)
	;
    *len = i;
    *val = malloc(i * sizeof(**val));
    if (i != 0 && *val == NULL) {
	ret = ENOMEM;
	krb5_set_error_string(context, "malloc: out of memory");
	goto cleanup;
    }
    memmove (*val,
	     etypes,
	     i * sizeof(*tmp));
cleanup:
    if (tmp != NULL)
	free (tmp);
    return ret;
}


static krb5_error_code
decrypt_tkt (krb5_context context,
	     krb5_keyblock *key,
	     krb5_key_usage usage,
	     krb5_const_pointer decrypt_arg,
	     krb5_kdc_rep *dec_rep)
{
    krb5_error_code ret;
    krb5_data data;
    size_t size;
    krb5_crypto crypto;

    ret = krb5_crypto_init(context, key, 0, &crypto);
    if (ret)
	return ret;

    ret = krb5_decrypt_EncryptedData (context,
				      crypto,
				      usage,
				      &dec_rep->kdc_rep.enc_part,
				      &data);
    krb5_crypto_destroy(context, crypto);

    if (ret)
	return ret;

    ret = krb5_decode_EncASRepPart(context,
				   data.data,
				   data.length,
				   &dec_rep->enc_part, 
				   &size);
    if (ret)
	ret = krb5_decode_EncTGSRepPart(context,
					data.data,
					data.length,
					&dec_rep->enc_part, 
					&size);
    krb5_data_free (&data);
    if (ret)
	return ret;
    return 0;
}

int
_krb5_extract_ticket(krb5_context context, 
		     krb5_kdc_rep *rep, 
		     krb5_creds *creds,		
		     krb5_keyblock *key,
		     krb5_const_pointer keyseed,
		     krb5_key_usage key_usage,
		     krb5_addresses *addrs,
		     unsigned nonce,
		     unsigned flags,
		     krb5_decrypt_proc decrypt_proc,
		     krb5_const_pointer decryptarg)
{
    krb5_error_code ret;
    krb5_principal tmp_principal;
    int tmp;
    size_t len;
    time_t tmp_time;
    krb5_timestamp sec_now;

/*
 * HACK:
 * this is really a ugly hack, to support using the Netbios Domain Name
 * as realm against windows KDC's, they always return the full realm
 * based on the DNS Name.
 */
flags |= EXTRACT_TICKET_ALLOW_SERVER_MISMATCH;
flags |=EXTRACT_TICKET_ALLOW_CNAME_MISMATCH ;

   ret = _krb5_principalname2krb5_principal (context,
					      &tmp_principal,
					      rep->kdc_rep.cname,
					      rep->kdc_rep.crealm);
    if (ret)
	goto out;

    /* compare client */

    if((flags & EXTRACT_TICKET_ALLOW_CNAME_MISMATCH) == 0){
	tmp = krb5_principal_compare (context, tmp_principal, creds->client);
	if (!tmp) {
	    krb5_free_principal (context, tmp_principal);
	    krb5_clear_error_string (context);
	    ret = KRB5KRB_AP_ERR_MODIFIED;
	    goto out;
	}
    }

    krb5_free_principal (context, creds->client);
    creds->client = tmp_principal;

    /* extract ticket */
    ASN1_MALLOC_ENCODE(Ticket, creds->ticket.data, creds->ticket.length, 
		       &rep->kdc_rep.ticket, &len, ret);
    if(ret)
	goto out;
    if (creds->ticket.length != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");
    creds->second_ticket.length = 0;
    creds->second_ticket.data   = NULL;

    /* compare server */

    ret = _krb5_principalname2krb5_principal (context,
					      &tmp_principal,
					      rep->kdc_rep.ticket.sname,
					      rep->kdc_rep.ticket.realm);
    if (ret)
	goto out;
    if(flags & EXTRACT_TICKET_ALLOW_SERVER_MISMATCH){
	krb5_free_principal(context, creds->server);
	creds->server = tmp_principal;
	tmp_principal = NULL;
    } else {
	tmp = krb5_principal_compare (context, tmp_principal,
				      creds->server);
	krb5_free_principal (context, tmp_principal);
	if (!tmp) {
	    ret = KRB5KRB_AP_ERR_MODIFIED;
	    krb5_clear_error_string (context);
	    goto out;
	}
    }
    
    /* decrypt */

    if (decrypt_proc == NULL)
	decrypt_proc = decrypt_tkt;
    
    ret = (*decrypt_proc)(context, key, key_usage, decryptarg, rep);
    if (ret)
	goto out;

    /* verify names */
    if(flags & EXTRACT_TICKET_MATCH_REALM){
	const char *srealm = krb5_principal_get_realm(context, creds->server);
	const char *crealm = krb5_principal_get_realm(context, creds->client);

	if (strcmp(rep->enc_part.srealm, srealm) != 0 ||
	    strcmp(rep->enc_part.srealm, crealm) != 0)
	{
	    ret = KRB5KRB_AP_ERR_MODIFIED;
	    krb5_clear_error_string(context);
	    goto out;
	}
    }

    /* compare nonces */

    if (nonce != rep->enc_part.nonce) {
	ret = KRB5KRB_AP_ERR_MODIFIED;
	krb5_set_error_string(context, "malloc: out of memory");
	goto out;
    }

    /* set kdc-offset */

    krb5_timeofday (context, &sec_now);
    if (rep->enc_part.flags.initial
	&& context->kdc_sec_offset == 0
	&& krb5_config_get_bool (context, NULL,
				 "libdefaults",
				 "kdc_timesync",
				 NULL)) {
	context->kdc_sec_offset = rep->enc_part.authtime - sec_now;
	krb5_timeofday (context, &sec_now);
    }

    /* check all times */

    if (rep->enc_part.starttime) {
	tmp_time = *rep->enc_part.starttime;
    } else
	tmp_time = rep->enc_part.authtime;

    if (creds->times.starttime == 0
	&& abs(tmp_time - sec_now) > context->max_skew) {
	ret = KRB5KRB_AP_ERR_SKEW;
	krb5_set_error_string (context,
			       "time skew (%d) larger than max (%d)",
			       abs(tmp_time - sec_now),
			       (int)context->max_skew);
	goto out;
    }

    if (creds->times.starttime != 0
	&& tmp_time != creds->times.starttime) {
	krb5_clear_error_string (context);
	ret = KRB5KRB_AP_ERR_MODIFIED;
	goto out;
    }

    creds->times.starttime = tmp_time;

    if (rep->enc_part.renew_till) {
	tmp_time = *rep->enc_part.renew_till;
    } else
	tmp_time = 0;

    if (creds->times.renew_till != 0
	&& tmp_time > creds->times.renew_till) {
	krb5_clear_error_string (context);
	ret = KRB5KRB_AP_ERR_MODIFIED;
	goto out;
    }

    creds->times.renew_till = tmp_time;

    creds->times.authtime = rep->enc_part.authtime;

    if (creds->times.endtime != 0
	&& rep->enc_part.endtime > creds->times.endtime) {
	krb5_clear_error_string (context);
	ret = KRB5KRB_AP_ERR_MODIFIED;
	goto out;
    }

    creds->times.endtime  = rep->enc_part.endtime;

    if(rep->enc_part.caddr)
	krb5_copy_addresses (context, rep->enc_part.caddr, &creds->addresses);
    else if(addrs)
	krb5_copy_addresses (context, addrs, &creds->addresses);
    else {
	creds->addresses.len = 0;
	creds->addresses.val = NULL;
    }
    creds->flags.b = rep->enc_part.flags;
	  
    creds->authdata.len = 0;
    creds->authdata.val = NULL;
    creds->session.keyvalue.length = 0;
    creds->session.keyvalue.data   = NULL;
    creds->session.keytype = rep->enc_part.key.keytype;
    ret = krb5_data_copy (&creds->session.keyvalue,
			  rep->enc_part.key.keyvalue.data,
			  rep->enc_part.key.keyvalue.length);

out:
    memset (rep->enc_part.key.keyvalue.data, 0,
	    rep->enc_part.key.keyvalue.length);
    return ret;
}


static krb5_error_code
make_pa_enc_timestamp(krb5_context context, PA_DATA *pa, 
		      krb5_enctype etype, krb5_keyblock *key)
{
    PA_ENC_TS_ENC p;
    unsigned char *buf;
    size_t buf_size;
    size_t len;
    EncryptedData encdata;
    krb5_error_code ret;
    int32_t usec;
    int usec2;
    krb5_crypto crypto;
    
    krb5_us_timeofday (context, &p.patimestamp, &usec);
    usec2         = usec;
    p.pausec      = &usec2;

    ASN1_MALLOC_ENCODE(PA_ENC_TS_ENC, buf, buf_size, &p, &len, ret);
    if (ret)
	return ret;
    if(buf_size != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");
    ret = krb5_crypto_init(context, key, 0, &crypto);
    if (ret) {
	free(buf);
	return ret;
    }
    ret = krb5_encrypt_EncryptedData(context, 
				     crypto,
				     KRB5_KU_PA_ENC_TIMESTAMP,
				     buf,
				     len,
				     0,
				     &encdata);
    free(buf);
    krb5_crypto_destroy(context, crypto);
    if (ret)
	return ret;
		    
    ASN1_MALLOC_ENCODE(EncryptedData, buf, buf_size, &encdata, &len, ret);
    free_EncryptedData(&encdata);
    if (ret)
	return ret;
    if(buf_size != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");
    pa->padata_type = KRB5_PADATA_ENC_TIMESTAMP;
    pa->padata_value.length = len;
    pa->padata_value.data = buf;
    return 0;
}

static krb5_error_code
add_padata(krb5_context context,
	   METHOD_DATA *md, 
	   krb5_principal client,
	   krb5_key_proc key_proc,
	   krb5_const_pointer keyseed,
	   krb5_enctype *enctypes,
	   unsigned netypes,
	   krb5_salt *salt)
{
    krb5_error_code ret;
    PA_DATA *pa2;
    krb5_salt salt2;
    krb5_enctype *ep;
    int i;
    
    if(salt == NULL) {
	/* default to standard salt */
	ret = krb5_get_pw_salt (context, client, &salt2);
	salt = &salt2;
    }
    if (!enctypes) {
	enctypes = context->etypes;
	netypes = 0;
	for (ep = enctypes; *ep != ETYPE_NULL; ep++)
	    netypes++;
    }
    pa2 = realloc (md->val, (md->len + netypes) * sizeof(*md->val));
    if (pa2 == NULL) {
	krb5_set_error_string(context, "malloc: out of memory");
	return ENOMEM;
    }
    md->val = pa2;

    for (i = 0; i < netypes; ++i) {
	krb5_keyblock *key;

	ret = (*key_proc)(context, enctypes[i], *salt, keyseed, &key);
	if (ret)
	    continue;
	ret = make_pa_enc_timestamp (context, &md->val[md->len],
				     enctypes[i], key);
	krb5_free_keyblock (context, key);
	if (ret)
	    return ret;
	++md->len;
    }