get_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: get_cred.c 22530 2008-01-27 11:48:16Z lha $");

/*
 * Take the `body' and encode it into `padata' using the credentials
 * in `creds'.
 */

static krb5_error_code
make_pa_tgs_req(krb5_context context, 
		krb5_auth_context ac,
		KDC_REQ_BODY *body,
		PA_DATA *padata,
		krb5_creds *creds,
		krb5_key_usage usage)
{
    u_char *buf;
    size_t buf_size;
    size_t len;
    krb5_data in_data;
    krb5_error_code ret;

    ASN1_MALLOC_ENCODE(KDC_REQ_BODY, buf, buf_size, body, &len, ret);
    if (ret)
	goto out;
    if(buf_size != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");

    in_data.length = len;
    in_data.data   = buf;
    ret = _krb5_mk_req_internal(context, &ac, 0, &in_data, creds,
				&padata->padata_value,
				KRB5_KU_TGS_REQ_AUTH_CKSUM,
				usage
				/* KRB5_KU_TGS_REQ_AUTH */);
 out:
    free (buf);
    if(ret)
	return ret;
    padata->padata_type = KRB5_PADATA_TGS_REQ;
    return 0;
}

/*
 * Set the `enc-authorization-data' in `req_body' based on `authdata'
 */

static krb5_error_code
set_auth_data (krb5_context context,
	       KDC_REQ_BODY *req_body,
	       krb5_authdata *authdata,
	       krb5_keyblock *key)
{
    if(authdata->len) {
	size_t len, buf_size;
	unsigned char *buf;
	krb5_crypto crypto;
	krb5_error_code ret;

	ASN1_MALLOC_ENCODE(AuthorizationData, buf, buf_size, authdata,
			   &len, ret);
	if (ret)
	    return ret;
	if (buf_size != len)
	    krb5_abortx(context, "internal error in ASN.1 encoder");

	ALLOC(req_body->enc_authorization_data, 1);
	if (req_body->enc_authorization_data == NULL) {
	    free (buf);
	    krb5_set_error_string(context, "malloc: out of memory");
	    return ENOMEM;
	}
	ret = krb5_crypto_init(context, key, 0, &crypto);
	if (ret) {
	    free (buf);
	    free (req_body->enc_authorization_data);
	    req_body->enc_authorization_data = NULL;
	    return ret;
	}
	krb5_encrypt_EncryptedData(context, 
				   crypto,
				   KRB5_KU_TGS_REQ_AUTH_DAT_SUBKEY, 
				   /* KRB5_KU_TGS_REQ_AUTH_DAT_SESSION? */
				   buf,
				   len,
				   0,
				   req_body->enc_authorization_data);
	free (buf);
	krb5_crypto_destroy(context, crypto);
    } else {
	req_body->enc_authorization_data = NULL;
    }
    return 0;
}    

/*
 * Create a tgs-req in `t' with `addresses', `flags', `second_ticket'
 * (if not-NULL), `in_creds', `krbtgt', and returning the generated
 * subkey in `subkey'.
 */

static krb5_error_code
init_tgs_req (krb5_context context,
	      krb5_ccache ccache,
	      krb5_addresses *addresses,
	      krb5_kdc_flags flags,
	      Ticket *second_ticket,
	      krb5_creds *in_creds,
	      krb5_creds *krbtgt,
	      unsigned nonce,
	      const METHOD_DATA *padata,
	      krb5_keyblock **subkey,
	      TGS_REQ *t,
	      krb5_key_usage usage)
{
    krb5_error_code ret = 0;

    memset(t, 0, sizeof(*t));
    t->pvno = 5;
    t->msg_type = krb_tgs_req;
    if (in_creds->session.keytype) {
	ALLOC_SEQ(&t->req_body.etype, 1);
	if(t->req_body.etype.val == NULL) {
	    ret = ENOMEM;
	    krb5_set_error_string(context, "malloc: out of memory");
	    goto fail;
	}
	t->req_body.etype.val[0] = in_creds->session.keytype;
    } else {
	ret = krb5_init_etype(context, 
			      &t->req_body.etype.len, 
			      &t->req_body.etype.val, 
			      NULL);
    }
    if (ret)
	goto fail;
    t->req_body.addresses = addresses;
    t->req_body.kdc_options = flags.b;
    ret = copy_Realm(&in_creds->server->realm, &t->req_body.realm);
    if (ret)
	goto fail;
    ALLOC(t->req_body.sname, 1);
    if (t->req_body.sname == NULL) {
	ret = ENOMEM;
	krb5_set_error_string(context, "malloc: out of memory");
	goto fail;
    }

    /* some versions of some code might require that the client be
       present in TGS-REQs, but this is clearly against the spec */

    ret = copy_PrincipalName(&in_creds->server->name, t->req_body.sname);
    if (ret)
	goto fail;

    /* req_body.till should be NULL if there is no endtime specified,
       but old MIT code (like DCE secd) doesn't like that */
    ALLOC(t->req_body.till, 1);
    if(t->req_body.till == NULL){
	ret = ENOMEM;
	krb5_set_error_string(context, "malloc: out of memory");
	goto fail;
    }
    *t->req_body.till = in_creds->times.endtime;
    
    t->req_body.nonce = nonce;
    if(second_ticket){
	ALLOC(t->req_body.additional_tickets, 1);
	if (t->req_body.additional_tickets == NULL) {
	    ret = ENOMEM;
	    krb5_set_error_string(context, "malloc: out of memory");
	    goto fail;
	}
	ALLOC_SEQ(t->req_body.additional_tickets, 1);
	if (t->req_body.additional_tickets->val == NULL) {
	    ret = ENOMEM;
	    krb5_set_error_string(context, "malloc: out of memory");
	    goto fail;
	}
	ret = copy_Ticket(second_ticket, t->req_body.additional_tickets->val); 
	if (ret)
	    goto fail;
    }
    ALLOC(t->padata, 1);
    if (t->padata == NULL) {
	ret = ENOMEM;
	krb5_set_error_string(context, "malloc: out of memory");
	goto fail;
    }
    ALLOC_SEQ(t->padata, 1 + padata->len);
    if (t->padata->val == NULL) {
	ret = ENOMEM;
	krb5_set_error_string(context, "malloc: out of memory");
	goto fail;
    }
    {
	int i;
	for (i = 0; i < padata->len; i++) {
	    ret = copy_PA_DATA(&padata->val[i], &t->padata->val[i + 1]);
	    if (ret) {
		krb5_set_error_string(context, "malloc: out of memory");
		goto fail;
	    }
	}
    }

    {
	krb5_auth_context ac;
	krb5_keyblock *key = NULL;

	ret = krb5_auth_con_init(context, &ac);
	if(ret)
	    goto fail;

	if (krb5_config_get_bool_default(context, NULL, FALSE,
					 "realms",
					 krbtgt->server->realm,
					 "tgs_require_subkey",
					 NULL))
	{
	    ret = krb5_generate_subkey (context, &krbtgt->session, &key);
	    if (ret) {
		krb5_auth_con_free (context, ac);
		goto fail;
	    }

	    ret = krb5_auth_con_setlocalsubkey(context, ac, key);
	    if (ret) {
		if (key)
		    krb5_free_keyblock (context, key);
		krb5_auth_con_free (context, ac);
		goto fail;
	    }
	}

	ret = set_auth_data (context, &t->req_body, &in_creds->authdata,
			     key ? key : &krbtgt->session);
	if (ret) {
	    if (key)
		krb5_free_keyblock (context, key);
	    krb5_auth_con_free (context, ac);
	    goto fail;
	}

	ret = make_pa_tgs_req(context,
			      ac,
			      &t->req_body, 
			      &t->padata->val[0],
			      krbtgt,
			      usage);
	if(ret) {
	    if (key)
		krb5_free_keyblock (context, key);
	    krb5_auth_con_free(context, ac);
	    goto fail;
	}
	*subkey = key;
	
	krb5_auth_con_free(context, ac);
    }
fail:
    if (ret) {
	t->req_body.addresses = NULL;
	free_TGS_REQ (t);
    }
    return ret;
}

krb5_error_code
_krb5_get_krbtgt(krb5_context context,
		 krb5_ccache  id,
		 krb5_realm realm,
		 krb5_creds **cred)
{
    krb5_error_code ret;
    krb5_creds tmp_cred;

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

    ret = krb5_cc_get_principal(context, id, &tmp_cred.client);
    if (ret)
	return ret;

    ret = krb5_make_principal(context, 
			      &tmp_cred.server,
			      realm,
			      KRB5_TGS_NAME,
			      realm,
			      NULL);
    if(ret) {
	krb5_free_principal(context, tmp_cred.client);
	return ret;
    }
    ret = krb5_get_credentials(context,
			       KRB5_GC_CACHED,
			       id,
			       &tmp_cred,
			       cred);
    krb5_free_principal(context, tmp_cred.client);
    krb5_free_principal(context, tmp_cred.server);
    if(ret)
	return ret;
    return 0;
}

/* DCE compatible decrypt proc */
static krb5_error_code
decrypt_tkt_with_subkey (krb5_context context,
			 krb5_keyblock *key,
			 krb5_key_usage usage,
			 krb5_const_pointer subkey,
			 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 && subkey){
	/* DCE compat -- try to decrypt with subkey */
	ret = krb5_crypto_init(context, subkey, 0, &crypto);
	if (ret)
	    return ret;
	ret = krb5_decrypt_EncryptedData (context,
					  crypto,
					  KRB5_KU_TGS_REP_ENC_PART_SUB_KEY,
					  &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);
    return ret;
}

static krb5_error_code
get_cred_kdc_usage(krb5_context context, 
		   krb5_ccache id, 
		   krb5_kdc_flags flags,
		   krb5_addresses *addresses, 
		   krb5_creds *in_creds,
		   krb5_creds *krbtgt,
		   krb5_principal impersonate_principal,
		   Ticket *second_ticket,
		   krb5_creds *out_creds,
		   krb5_key_usage usage)
{
    TGS_REQ req;
    krb5_data enc;
    krb5_data resp;
    krb5_kdc_rep rep;
    KRB_ERROR error;
    krb5_error_code ret;
    unsigned nonce;
    krb5_keyblock *subkey = NULL;
    size_t len;
    Ticket second_ticket_data;
    METHOD_DATA padata;
    
    krb5_data_zero(&resp);
    krb5_data_zero(&enc);
    padata.val = NULL;
    padata.len = 0;

    krb5_generate_random_block(&nonce, sizeof(nonce));
    nonce &= 0xffffffff;
    
    if(flags.b.enc_tkt_in_skey && second_ticket == NULL){