1 /*
2 * Copyright (c) 2006 - 2007 Kungliga Tekniska Högskolan
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 #include <hex.h>
36 #include <rfc2459_asn1.h>
37 #include <hx509.h>
38
39 #ifdef KX509
40
41 /*
42 *
43 */
44
45 krb5_error_code
_kdc_try_kx509_request(void * ptr,size_t len,struct Kx509Request * req,size_t * size)46 _kdc_try_kx509_request(void *ptr, size_t len, struct Kx509Request *req, size_t *size)
47 {
48 if (len < 4)
49 return -1;
50 if (memcmp("\x00\x00\x02\x00", ptr, 4) != 0)
51 return -1;
52 return decode_Kx509Request(((unsigned char *)ptr) + 4, len - 4, req, size);
53 }
54
55 /*
56 *
57 */
58
59 static const unsigned char version_2_0[4] = {0 , 0, 2, 0};
60
61 static krb5_error_code
verify_req_hash(krb5_context context,const Kx509Request * req,krb5_keyblock * key)62 verify_req_hash(krb5_context context,
63 const Kx509Request *req,
64 krb5_keyblock *key)
65 {
66 unsigned char digest[SHA_DIGEST_LENGTH];
67 HMAC_CTX *ctx;
68
69 if (req->pk_hash.length != sizeof(digest)) {
70 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
71 "pk-hash have wrong length: %lu",
72 (unsigned long)req->pk_hash.length);
73 return KRB5KDC_ERR_PREAUTH_FAILED;
74 }
75
76 ctx = HMAC_CTX_new();
77 if (ctx == NULL) {
78 krb5_set_error_message(context, ENOMEM,
79 "HMAC context malloc failed");
80 return ENOMEM;
81 }
82 HMAC_Init_ex(ctx,
83 key->keyvalue.data, key->keyvalue.length,
84 EVP_sha1(), NULL);
85 if (sizeof(digest) != HMAC_size(ctx))
86 krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509");
87 HMAC_Update(ctx, version_2_0, sizeof(version_2_0));
88 HMAC_Update(ctx, req->pk_key.data, req->pk_key.length);
89 HMAC_Final(ctx, digest, 0);
90 HMAC_CTX_free(ctx);
91
92 if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) {
93 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED,
94 "pk-hash is not correct");
95 return KRB5KDC_ERR_PREAUTH_FAILED;
96 }
97 return 0;
98 }
99
100 static krb5_error_code
calculate_reply_hash(krb5_context context,krb5_keyblock * key,Kx509Response * rep)101 calculate_reply_hash(krb5_context context,
102 krb5_keyblock *key,
103 Kx509Response *rep)
104 {
105 krb5_error_code ret;
106 HMAC_CTX *ctx;
107
108 ctx = HMAC_CTX_new();
109 if (ctx == NULL) {
110 krb5_set_error_message(context, ENOMEM,
111 "HMAC context malloc failed");
112 return ENOMEM;
113 }
114
115 HMAC_Init_ex(ctx, key->keyvalue.data, key->keyvalue.length,
116 EVP_sha1(), NULL);
117 ret = krb5_data_alloc(rep->hash, HMAC_size(ctx));
118 if (ret) {
119 HMAC_CTX_free(ctx);
120 krb5_set_error_message(context, ENOMEM, "malloc: out of memory");
121 return ENOMEM;
122 }
123
124 HMAC_Update(ctx, version_2_0, sizeof(version_2_0));
125 if (rep->error_code) {
126 int32_t t = *rep->error_code;
127 do {
128 unsigned char p = (t & 0xff);
129 HMAC_Update(ctx, &p, 1);
130 t >>= 8;
131 } while (t);
132 }
133 if (rep->certificate)
134 HMAC_Update(ctx, rep->certificate->data, rep->certificate->length);
135 if (rep->e_text)
136 HMAC_Update(ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text));
137
138 HMAC_Final(ctx, rep->hash->data, 0);
139 HMAC_CTX_free(ctx);
140
141 return 0;
142 }
143
144 /*
145 * Build a certifate for `principal´ that will expire at `endtime´.
146 */
147
148 static krb5_error_code
build_certificate(krb5_context context,krb5_kdc_configuration * config,const krb5_data * key,time_t endtime,krb5_principal principal,krb5_data * certificate)149 build_certificate(krb5_context context,
150 krb5_kdc_configuration *config,
151 const krb5_data *key,
152 time_t endtime,
153 krb5_principal principal,
154 krb5_data *certificate)
155 {
156 hx509_ca_tbs tbs = NULL;
157 hx509_env env = NULL;
158 hx509_cert cert = NULL;
159 hx509_cert signer = NULL;
160 int ret;
161
162 if (krb5_principal_get_comp_string(context, principal, 1) != NULL) {
163 kdc_log(context, config, 0, "Principal is not a user");
164 return EINVAL;
165 }
166
167 ret = hx509_env_add(context->hx509ctx, &env, "principal-name",
168 krb5_principal_get_comp_string(context, principal, 0));
169 if (ret)
170 goto out;
171
172 {
173 hx509_certs certs;
174 hx509_query *q;
175
176 ret = hx509_certs_init(context->hx509ctx, config->kx509_ca, 0,
177 NULL, &certs);
178 if (ret) {
179 kdc_log(context, config, 0, "Failed to load CA %s",
180 config->kx509_ca);
181 goto out;
182 }
183 ret = hx509_query_alloc(context->hx509ctx, &q);
184 if (ret) {
185 hx509_certs_free(&certs);
186 goto out;
187 }
188
189 hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY);
190 hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN);
191
192 ret = hx509_certs_find(context->hx509ctx, certs, q, &signer);
193 hx509_query_free(context->hx509ctx, q);
194 hx509_certs_free(&certs);
195 if (ret) {
196 kdc_log(context, config, 0, "Failed to find a CA in %s",
197 config->kx509_ca);
198 goto out;
199 }
200 }
201
202 ret = hx509_ca_tbs_init(context->hx509ctx, &tbs);
203 if (ret)
204 goto out;
205
206 {
207 SubjectPublicKeyInfo spki;
208 heim_any any;
209
210 memset(&spki, 0, sizeof(spki));
211
212 spki.subjectPublicKey.data = key->data;
213 spki.subjectPublicKey.length = key->length * 8;
214
215 ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption,
216 &spki.algorithm.algorithm);
217
218 any.data = "\x05\x00";
219 any.length = 2;
220 spki.algorithm.parameters = &any;
221
222 ret = hx509_ca_tbs_set_spki(context->hx509ctx, tbs, &spki);
223 der_free_oid(&spki.algorithm.algorithm);
224 if (ret)
225 goto out;
226 }
227
228 {
229 hx509_certs certs;
230 hx509_cert template;
231
232 ret = hx509_certs_init(context->hx509ctx, config->kx509_template, 0,
233 NULL, &certs);
234 if (ret) {
235 kdc_log(context, config, 0, "Failed to load template %s",
236 config->kx509_template);
237 goto out;
238 }
239 ret = hx509_get_one_cert(context->hx509ctx, certs, &template);
240 hx509_certs_free(&certs);
241 if (ret) {
242 kdc_log(context, config, 0, "Failed to find template in %s",
243 config->kx509_template);
244 goto out;
245 }
246 ret = hx509_ca_tbs_set_template(context->hx509ctx, tbs,
247 HX509_CA_TEMPLATE_SUBJECT|
248 HX509_CA_TEMPLATE_KU|
249 HX509_CA_TEMPLATE_EKU,
250 template);
251 hx509_cert_free(template);
252 if (ret)
253 goto out;
254 }
255
256 hx509_ca_tbs_set_notAfter(context->hx509ctx, tbs, endtime);
257
258 hx509_ca_tbs_subject_expand(context->hx509ctx, tbs, env);
259 hx509_env_free(&env);
260
261 ret = hx509_ca_sign(context->hx509ctx, tbs, signer, &cert);
262 hx509_cert_free(signer);
263 if (ret)
264 goto out;
265
266 hx509_ca_tbs_free(&tbs);
267
268 ret = hx509_cert_binary(context->hx509ctx, cert, certificate);
269 hx509_cert_free(cert);
270 if (ret)
271 goto out;
272
273 return 0;
274 out:
275 if (env)
276 hx509_env_free(&env);
277 if (tbs)
278 hx509_ca_tbs_free(&tbs);
279 if (signer)
280 hx509_cert_free(signer);
281 krb5_set_error_message(context, ret, "cert creation failed");
282 return ret;
283 }
284
285 /*
286 *
287 */
288
289 krb5_error_code
_kdc_do_kx509(krb5_context context,krb5_kdc_configuration * config,const struct Kx509Request * req,krb5_data * reply,const char * from,struct sockaddr * addr)290 _kdc_do_kx509(krb5_context context,
291 krb5_kdc_configuration *config,
292 const struct Kx509Request *req, krb5_data *reply,
293 const char *from, struct sockaddr *addr)
294 {
295 krb5_error_code ret;
296 krb5_ticket *ticket = NULL;
297 krb5_flags ap_req_options;
298 krb5_auth_context ac = NULL;
299 krb5_keytab id = NULL;
300 krb5_principal sprincipal = NULL, cprincipal = NULL;
301 char *cname = NULL;
302 Kx509Response rep;
303 size_t size;
304 krb5_keyblock *key = NULL;
305
306 krb5_data_zero(reply);
307 memset(&rep, 0, sizeof(rep));
308
309 if(!config->enable_kx509) {
310 kdc_log(context, config, 0,
311 "Rejected kx509 request (disabled) from %s", from);
312 return KRB5KDC_ERR_POLICY;
313 }
314
315 kdc_log(context, config, 0, "Kx509 request from %s", from);
316
317 ret = krb5_kt_resolve(context, "HDB:", &id);
318 if (ret) {
319 kdc_log(context, config, 0, "Can't open database for digest");
320 goto out;
321 }
322
323 ret = krb5_rd_req(context,
324 &ac,
325 &req->authenticator,
326 NULL,
327 id,
328 &ap_req_options,
329 &ticket);
330 if (ret)
331 goto out;
332
333 ret = krb5_ticket_get_client(context, ticket, &cprincipal);
334 if (ret)
335 goto out;
336
337 ret = krb5_unparse_name(context, cprincipal, &cname);
338 if (ret)
339 goto out;
340
341 /* verify server principal */
342
343 ret = krb5_sname_to_principal(context, NULL, "kca_service",
344 KRB5_NT_UNKNOWN, &sprincipal);
345 if (ret)
346 goto out;
347
348 {
349 krb5_principal principal = NULL;
350
351 ret = krb5_ticket_get_server(context, ticket, &principal);
352 if (ret)
353 goto out;
354
355 ret = krb5_principal_compare(context, sprincipal, principal);
356 krb5_free_principal(context, principal);
357 if (ret != TRUE) {
358 char *expected, *used;
359
360 ret = krb5_unparse_name(context, sprincipal, &expected);
361 if (ret)
362 goto out;
363 ret = krb5_unparse_name(context, principal, &used);
364 if (ret) {
365 krb5_xfree(expected);
366 goto out;
367 }
368
369 ret = KRB5KDC_ERR_SERVER_NOMATCH;
370 krb5_set_error_message(context, ret,
371 "User %s used wrong Kx509 service "
372 "principal, expected: %s, used %s",
373 cname, expected, used);
374 krb5_xfree(expected);
375 krb5_xfree(used);
376 goto out;
377 }
378 }
379
380 ret = krb5_auth_con_getkey(context, ac, &key);
381 if (ret == 0 && key == NULL)
382 ret = KRB5KDC_ERR_NULL_KEY;
383 if (ret) {
384 krb5_set_error_message(context, ret, "Kx509 can't get session key");
385 goto out;
386 }
387
388 ret = verify_req_hash(context, req, key);
389 if (ret)
390 goto out;
391
392 /* Verify that the key is encoded RSA key */
393 {
394 RSAPublicKey key;
395 size_t size;
396
397 ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length,
398 &key, &size);
399 if (ret)
400 goto out;
401 free_RSAPublicKey(&key);
402 if (size != req->pk_key.length) {
403 ret = ASN1_EXTRA_DATA;
404 goto out;
405 }
406 }
407
408 ALLOC(rep.certificate);
409 if (rep.certificate == NULL)
410 goto out;
411 krb5_data_zero(rep.certificate);
412 ALLOC(rep.hash);
413 if (rep.hash == NULL)
414 goto out;
415 krb5_data_zero(rep.hash);
416
417 ret = build_certificate(context, config, &req->pk_key,
418 krb5_ticket_get_endtime(context, ticket),
419 cprincipal, rep.certificate);
420 if (ret)
421 goto out;
422
423 ret = calculate_reply_hash(context, key, &rep);
424 if (ret)
425 goto out;
426
427 /*
428 * Encode reply, [ version | Kx509Response ]
429 */
430
431 {
432 krb5_data data;
433
434 ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep,
435 &size, ret);
436 if (ret) {
437 krb5_set_error_message(context, ret, "Failed to encode kx509 reply");
438 goto out;
439 }
440 if (size != data.length)
441 krb5_abortx(context, "ASN1 internal error");
442
443 ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0));
444 if (ret) {
445 free(data.data);
446 goto out;
447 }
448 memcpy(reply->data, version_2_0, sizeof(version_2_0));
449 memcpy(((unsigned char *)reply->data) + sizeof(version_2_0),
450 data.data, data.length);
451 free(data.data);
452 }
453
454 kdc_log(context, config, 0, "Successful Kx509 request for %s", cname);
455
456 out:
457 if (ac)
458 krb5_auth_con_free(context, ac);
459 if (ret)
460 krb5_warn(context, ret, "Kx509 request from %s failed", from);
461 if (ticket)
462 krb5_free_ticket(context, ticket);
463 if (id)
464 krb5_kt_close(context, id);
465 if (sprincipal)
466 krb5_free_principal(context, sprincipal);
467 if (cprincipal)
468 krb5_free_principal(context, cprincipal);
469 if (key)
470 krb5_free_keyblock (context, key);
471 if (cname)
472 free(cname);
473 free_Kx509Response(&rep);
474
475 return 0;
476 }
477
478 #endif /* KX509 */
479