1/*
2 * Copyright (c) 1997-2005 Kungliga Tekniska H�gskolan
3 * (Royal Institute of Technology, Stockholm, Sweden).
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the Institute nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include "kdc_locl.h"
35
36RCSID("$Id: 524.c 18270 2006-10-06 17:06:30Z lha $");
37
38#include <krb5-v4compat.h>
39
40/*
41 * fetch the server from `t', returning the name in malloced memory in
42 * `spn' and the entry itself in `server'
43 */
44
45static krb5_error_code
46fetch_server (krb5_context context,
47	      krb5_kdc_configuration *config,
48	      const Ticket *t,
49	      char **spn,
50	      hdb_entry_ex **server,
51	      const char *from)
52{
53    krb5_error_code ret;
54    krb5_principal sprinc;
55
56    ret = _krb5_principalname2krb5_principal(context, &sprinc,
57					     t->sname, t->realm);
58    if (ret) {
59	kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
60		krb5_get_err_text(context, ret));
61	return ret;
62    }
63    ret = krb5_unparse_name(context, sprinc, spn);
64    if (ret) {
65	krb5_free_principal(context, sprinc);
66	kdc_log(context, config, 0, "krb5_unparse_name: %s",
67		krb5_get_err_text(context, ret));
68	return ret;
69    }
70    ret = _kdc_db_fetch(context, config, sprinc, HDB_F_GET_SERVER,
71			NULL, server);
72    krb5_free_principal(context, sprinc);
73    if (ret) {
74	kdc_log(context, config, 0,
75	"Request to convert ticket from %s for unknown principal %s: %s",
76		from, *spn, krb5_get_err_text(context, ret));
77	if (ret == HDB_ERR_NOENTRY)
78	    ret = KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN;
79	return ret;
80    }
81    return 0;
82}
83
84static krb5_error_code
85log_524 (krb5_context context,
86	 krb5_kdc_configuration *config,
87	 const EncTicketPart *et,
88	 const char *from,
89	 const char *spn)
90{
91    krb5_principal client;
92    char *cpn;
93    krb5_error_code ret;
94
95    ret = _krb5_principalname2krb5_principal(context, &client,
96					     et->cname, et->crealm);
97    if (ret) {
98	kdc_log(context, config, 0, "_krb5_principalname2krb5_principal: %s",
99		krb5_get_err_text (context, ret));
100	return ret;
101    }
102    ret = krb5_unparse_name(context, client, &cpn);
103    if (ret) {
104	krb5_free_principal(context, client);
105	kdc_log(context, config, 0, "krb5_unparse_name: %s",
106		krb5_get_err_text (context, ret));
107	return ret;
108    }
109    kdc_log(context, config, 1, "524-REQ %s from %s for %s", cpn, from, spn);
110    free(cpn);
111    krb5_free_principal(context, client);
112    return 0;
113}
114
115static krb5_error_code
116verify_flags (krb5_context context,
117	      krb5_kdc_configuration *config,
118	      const EncTicketPart *et,
119	      const char *spn)
120{
121    if(et->endtime < kdc_time){
122	kdc_log(context, config, 0, "Ticket expired (%s)", spn);
123	return KRB5KRB_AP_ERR_TKT_EXPIRED;
124    }
125    if(et->flags.invalid){
126	kdc_log(context, config, 0, "Ticket not valid (%s)", spn);
127	return KRB5KRB_AP_ERR_TKT_NYV;
128    }
129    return 0;
130}
131
132/*
133 * set the `et->caddr' to the most appropriate address to use, where
134 * `addr' is the address the request was received from.
135 */
136
137static krb5_error_code
138set_address (krb5_context context,
139	     krb5_kdc_configuration *config,
140	     EncTicketPart *et,
141	     struct sockaddr *addr,
142	     const char *from)
143{
144    krb5_error_code ret;
145    krb5_address *v4_addr;
146
147    v4_addr = malloc (sizeof(*v4_addr));
148    if (v4_addr == NULL)
149	return ENOMEM;
150
151    ret = krb5_sockaddr2address(context, addr, v4_addr);
152    if(ret) {
153	free (v4_addr);
154	kdc_log(context, config, 0, "Failed to convert address (%s)", from);
155	return ret;
156    }
157
158    if (et->caddr && !krb5_address_search (context, v4_addr, et->caddr)) {
159	kdc_log(context, config, 0, "Incorrect network address (%s)", from);
160	krb5_free_address(context, v4_addr);
161	free (v4_addr);
162	return KRB5KRB_AP_ERR_BADADDR;
163    }
164    if(v4_addr->addr_type == KRB5_ADDRESS_INET) {
165	/* we need to collapse the addresses in the ticket to a
166	   single address; best guess is to use the address the
167	   connection came from */
168
169	if (et->caddr != NULL) {
170	    free_HostAddresses(et->caddr);
171	} else {
172	    et->caddr = malloc (sizeof (*et->caddr));
173	    if (et->caddr == NULL) {
174		krb5_free_address(context, v4_addr);
175		free(v4_addr);
176		return ENOMEM;
177	    }
178	}
179	et->caddr->val = v4_addr;
180	et->caddr->len = 1;
181    } else {
182	krb5_free_address(context, v4_addr);
183	free(v4_addr);
184    }
185    return 0;
186}
187
188
189static krb5_error_code
190encrypt_v4_ticket(krb5_context context,
191		  krb5_kdc_configuration *config,
192		  void *buf,
193		  size_t len,
194		  krb5_keyblock *skey,
195		  EncryptedData *reply)
196{
197    krb5_crypto crypto;
198    krb5_error_code ret;
199    ret = krb5_crypto_init(context, skey, ETYPE_DES_PCBC_NONE, &crypto);
200    if (ret) {
201	free(buf);
202	kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
203		krb5_get_err_text(context, ret));
204	return ret;
205    }
206
207    ret = krb5_encrypt_EncryptedData(context,
208				     crypto,
209				     KRB5_KU_TICKET,
210				     buf,
211				     len,
212				     0,
213				     reply);
214    krb5_crypto_destroy(context, crypto);
215    if(ret) {
216	kdc_log(context, config, 0, "Failed to encrypt data: %s",
217		krb5_get_err_text(context, ret));
218	return ret;
219    }
220    return 0;
221}
222
223static krb5_error_code
224encode_524_response(krb5_context context,
225		    krb5_kdc_configuration *config,
226		    const char *spn, const EncTicketPart et,
227		    const Ticket *t, hdb_entry_ex *server,
228		    EncryptedData *ticket, int *kvno)
229{
230    krb5_error_code ret;
231    int use_2b;
232    size_t len;
233
234    use_2b = krb5_config_get_bool(context, NULL, "kdc", "use_2b", spn, NULL);
235    if(use_2b) {
236	ASN1_MALLOC_ENCODE(EncryptedData,
237			   ticket->cipher.data, ticket->cipher.length,
238			   &t->enc_part, &len, ret);
239
240	if (ret) {
241	    kdc_log(context, config, 0,
242		    "Failed to encode v4 (2b) ticket (%s)", spn);
243	    return ret;
244	}
245
246	ticket->etype = 0;
247	ticket->kvno = NULL;
248	*kvno = 213; /* 2b's use this magic kvno */
249    } else {
250	unsigned char buf[MAX_KTXT_LEN + 4 * 4];
251	Key *skey;
252
253	if (!config->enable_v4_cross_realm && strcmp (et.crealm, t->realm) != 0) {
254	    kdc_log(context, config, 0, "524 cross-realm %s -> %s disabled", et.crealm,
255		    t->realm);
256	    return KRB5KDC_ERR_POLICY;
257	}
258
259	ret = _kdc_encode_v4_ticket(context, config,
260				    buf + sizeof(buf) - 1, sizeof(buf),
261				    &et, &t->sname, &len);
262	if(ret){
263	    kdc_log(context, config, 0,
264		    "Failed to encode v4 ticket (%s)", spn);
265	    return ret;
266	}
267	ret = _kdc_get_des_key(context, server, TRUE, FALSE, &skey);
268	if(ret){
269	    kdc_log(context, config, 0,
270		    "no suitable DES key for server (%s)", spn);
271	    return ret;
272	}
273	ret = encrypt_v4_ticket(context, config, buf + sizeof(buf) - len, len,
274				&skey->key, ticket);
275	if(ret){
276	    kdc_log(context, config, 0,
277		    "Failed to encrypt v4 ticket (%s)", spn);
278	    return ret;
279	}
280	*kvno = server->entry.kvno;
281    }
282
283    return 0;
284}
285
286/*
287 * process a 5->4 request, based on `t', and received `from, addr',
288 * returning the reply in `reply'
289 */
290
291krb5_error_code
292_kdc_do_524(krb5_context context,
293	    krb5_kdc_configuration *config,
294	    const Ticket *t, krb5_data *reply,
295	    const char *from, struct sockaddr *addr)
296{
297    krb5_error_code ret = 0;
298    krb5_crypto crypto;
299    hdb_entry_ex *server = NULL;
300    Key *skey;
301    krb5_data et_data;
302    EncTicketPart et;
303    EncryptedData ticket;
304    krb5_storage *sp;
305    char *spn = NULL;
306    unsigned char buf[MAX_KTXT_LEN + 4 * 4];
307    size_t len;
308    int kvno = 0;
309
310    if(!config->enable_524) {
311	ret = KRB5KDC_ERR_POLICY;
312	kdc_log(context, config, 0,
313		"Rejected ticket conversion request from %s", from);
314	goto out;
315    }
316
317    ret = fetch_server (context, config, t, &spn, &server, from);
318    if (ret) {
319	goto out;
320    }
321
322    ret = hdb_enctype2key(context, &server->entry, t->enc_part.etype, &skey);
323    if(ret){
324	kdc_log(context, config, 0,
325		"No suitable key found for server (%s) from %s", spn, from);
326	goto out;
327    }
328    ret = krb5_crypto_init(context, &skey->key, 0, &crypto);
329    if (ret) {
330	kdc_log(context, config, 0, "krb5_crypto_init failed: %s",
331		krb5_get_err_text(context, ret));
332	goto out;
333    }
334    ret = krb5_decrypt_EncryptedData (context,
335				      crypto,
336				      KRB5_KU_TICKET,
337				      &t->enc_part,
338				      &et_data);
339    krb5_crypto_destroy(context, crypto);
340    if(ret){
341	kdc_log(context, config, 0,
342		"Failed to decrypt ticket from %s for %s", from, spn);
343	goto out;
344    }
345    ret = krb5_decode_EncTicketPart(context, et_data.data, et_data.length,
346				    &et, &len);
347    krb5_data_free(&et_data);
348    if(ret){
349	kdc_log(context, config, 0,
350		"Failed to decode ticket from %s for %s", from, spn);
351	goto out;
352    }
353
354    ret = log_524 (context, config, &et, from, spn);
355    if (ret) {
356	free_EncTicketPart(&et);
357	goto out;
358    }
359
360    ret = verify_flags (context, config, &et, spn);
361    if (ret) {
362	free_EncTicketPart(&et);
363	goto out;
364    }
365
366    ret = set_address (context, config, &et, addr, from);
367    if (ret) {
368	free_EncTicketPart(&et);
369	goto out;
370    }
371
372    ret = encode_524_response(context, config, spn, et, t,
373			      server, &ticket, &kvno);
374    free_EncTicketPart(&et);
375
376 out:
377    /* make reply */
378    memset(buf, 0, sizeof(buf));
379    sp = krb5_storage_from_mem(buf, sizeof(buf));
380    if (sp) {
381	krb5_store_int32(sp, ret);
382	if(ret == 0){
383	    krb5_store_int32(sp, kvno);
384	    krb5_store_data(sp, ticket.cipher);
385	    /* Aargh! This is coded as a KTEXT_ST. */
386	    krb5_storage_seek(sp, MAX_KTXT_LEN - ticket.cipher.length, SEEK_CUR);
387	    krb5_store_int32(sp, 0); /* mbz */
388	    free_EncryptedData(&ticket);
389	}
390	ret = krb5_storage_to_data(sp, reply);
391	reply->length = krb5_storage_seek(sp, 0, SEEK_CUR);
392	krb5_storage_free(sp);
393    } else
394	krb5_data_zero(reply);
395    if(spn)
396	free(spn);
397    if(server)
398	_kdc_free_ent (context, server);
399    return ret;
400}
401