1/* 2 * Copyright (c) 2006 - 2007 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#include <hex.h> 36#include <rfc2459_asn1.h> 37#include <hx509.h> 38 39#ifdef KX509 40 41/* 42 * 43 */ 44 45krb5_error_code 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 59static const unsigned char version_2_0[4] = {0 , 0, 2, 0}; 60 61static krb5_error_code 62verify_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 HMAC_CTX_init(&ctx); 77 HMAC_Init_ex(&ctx, 78 key->keyvalue.data, key->keyvalue.length, 79 EVP_sha1(), NULL); 80 if (sizeof(digest) != HMAC_size(&ctx)) 81 krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509"); 82 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 83 HMAC_Update(&ctx, req->pk_key.data, req->pk_key.length); 84 HMAC_Final(&ctx, digest, 0); 85 HMAC_CTX_cleanup(&ctx); 86 87 if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) { 88 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED, 89 "pk-hash is not correct"); 90 return KRB5KDC_ERR_PREAUTH_FAILED; 91 } 92 return 0; 93} 94 95static krb5_error_code 96calculate_reply_hash(krb5_context context, 97 krb5_keyblock *key, 98 Kx509Response *rep) 99{ 100 krb5_error_code ret; 101 HMAC_CTX ctx; 102 103 HMAC_CTX_init(&ctx); 104 105 HMAC_Init_ex(&ctx, key->keyvalue.data, key->keyvalue.length, 106 EVP_sha1(), NULL); 107 ret = krb5_data_alloc(rep->hash, HMAC_size(&ctx)); 108 if (ret) { 109 HMAC_CTX_cleanup(&ctx); 110 krb5_set_error_message(context, ENOMEM, "malloc: out of memory"); 111 return ENOMEM; 112 } 113 114 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 115 if (rep->error_code) { 116 int32_t t = *rep->error_code; 117 do { 118 unsigned char p = (t & 0xff); 119 HMAC_Update(&ctx, &p, 1); 120 t >>= 8; 121 } while (t); 122 } 123 if (rep->certificate) 124 HMAC_Update(&ctx, rep->certificate->data, rep->certificate->length); 125 if (rep->e_text) 126 HMAC_Update(&ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text)); 127 128 HMAC_Final(&ctx, rep->hash->data, 0); 129 HMAC_CTX_cleanup(&ctx); 130 131 return 0; 132} 133 134/* 135 * Build a certifate for `principal�� that will expire at `endtime��. 136 */ 137 138static krb5_error_code 139build_certificate(krb5_context context, 140 krb5_kdc_configuration *config, 141 const krb5_data *key, 142 time_t endtime, 143 krb5_principal principal, 144 krb5_data *certificate) 145{ 146 hx509_context hxctx = NULL; 147 hx509_ca_tbs tbs = NULL; 148 hx509_env env = NULL; 149 hx509_cert cert = NULL; 150 hx509_cert signer = NULL; 151 int ret; 152 153 if (krb5_principal_get_comp_string(context, principal, 1) != NULL) { 154 kdc_log(context, config, 0, "Principal is not a user"); 155 return EINVAL; 156 } 157 158 ret = hx509_context_init(&hxctx); 159 if (ret) 160 goto out; 161 162 ret = hx509_env_add(hxctx, &env, "principal-name", 163 krb5_principal_get_comp_string(context, principal, 0)); 164 if (ret) 165 goto out; 166 167 { 168 hx509_certs certs; 169 hx509_query *q; 170 171 ret = hx509_certs_init(hxctx, config->kx509_ca, 0, 172 NULL, &certs); 173 if (ret) { 174 kdc_log(context, config, 0, "Failed to load CA %s", 175 config->kx509_ca); 176 goto out; 177 } 178 ret = hx509_query_alloc(hxctx, &q); 179 if (ret) { 180 hx509_certs_free(&certs); 181 goto out; 182 } 183 184 hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY); 185 hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN); 186 187 ret = hx509_certs_find(hxctx, certs, q, &signer); 188 hx509_query_free(hxctx, q); 189 hx509_certs_free(&certs); 190 if (ret) { 191 kdc_log(context, config, 0, "Failed to find a CA in %s", 192 config->kx509_ca); 193 goto out; 194 } 195 } 196 197 ret = hx509_ca_tbs_init(hxctx, &tbs); 198 if (ret) 199 goto out; 200 201 { 202 SubjectPublicKeyInfo spki; 203 heim_any any; 204 205 memset(&spki, 0, sizeof(spki)); 206 207 spki.subjectPublicKey.data = key->data; 208 spki.subjectPublicKey.length = key->length * 8; 209 210 ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption, 211 &spki.algorithm.algorithm); 212 213 any.data = "\x05\x00"; 214 any.length = 2; 215 spki.algorithm.parameters = &any; 216 217 ret = hx509_ca_tbs_set_spki(hxctx, tbs, &spki); 218 der_free_oid(&spki.algorithm.algorithm); 219 if (ret) 220 goto out; 221 } 222 223 { 224 hx509_certs certs; 225 hx509_cert template; 226 227 ret = hx509_certs_init(hxctx, config->kx509_template, 0, 228 NULL, &certs); 229 if (ret) { 230 kdc_log(context, config, 0, "Failed to load template %s", 231 config->kx509_template); 232 goto out; 233 } 234 ret = hx509_get_one_cert(hxctx, certs, &template); 235 hx509_certs_free(&certs); 236 if (ret) { 237 kdc_log(context, config, 0, "Failed to find template in %s", 238 config->kx509_template); 239 goto out; 240 } 241 ret = hx509_ca_tbs_set_template(hxctx, tbs, 242 HX509_CA_TEMPLATE_SUBJECT| 243 HX509_CA_TEMPLATE_KU| 244 HX509_CA_TEMPLATE_EKU, 245 template); 246 hx509_cert_free(template); 247 if (ret) 248 goto out; 249 } 250 251 hx509_ca_tbs_set_notAfter(hxctx, tbs, endtime); 252 253 hx509_ca_tbs_subject_expand(hxctx, tbs, env); 254 hx509_env_free(&env); 255 256 ret = hx509_ca_sign(hxctx, tbs, signer, &cert); 257 hx509_cert_free(signer); 258 if (ret) 259 goto out; 260 261 hx509_ca_tbs_free(&tbs); 262 263 ret = hx509_cert_binary(hxctx, cert, certificate); 264 hx509_cert_free(cert); 265 if (ret) 266 goto out; 267 268 hx509_context_free(&hxctx); 269 270 return 0; 271out: 272 if (env) 273 hx509_env_free(&env); 274 if (tbs) 275 hx509_ca_tbs_free(&tbs); 276 if (signer) 277 hx509_cert_free(signer); 278 if (hxctx) 279 hx509_context_free(&hxctx); 280 krb5_set_error_message(context, ret, "cert creation failed"); 281 return ret; 282} 283 284/* 285 * 286 */ 287 288krb5_error_code 289_kdc_do_kx509(krb5_context context, 290 krb5_kdc_configuration *config, 291 const struct Kx509Request *req, krb5_data *reply, 292 const char *from, struct sockaddr *addr) 293{ 294 krb5_error_code ret; 295 krb5_ticket *ticket = NULL; 296 krb5_flags ap_req_options; 297 krb5_auth_context ac = NULL; 298 krb5_keytab id = NULL; 299 krb5_principal sprincipal = NULL, cprincipal = NULL; 300 char *cname = NULL; 301 Kx509Response rep; 302 size_t size; 303 krb5_keyblock *key = NULL; 304 305 krb5_data_zero(reply); 306 memset(&rep, 0, sizeof(rep)); 307 308 if(!config->enable_kx509) { 309 kdc_log(context, config, 0, 310 "Rejected kx509 request (disabled) from %s", from); 311 return KRB5KDC_ERR_POLICY; 312 } 313 314 kdc_log(context, config, 0, "Kx509 request from %s", from); 315 316 ret = krb5_kt_resolve(context, "HDB:", &id); 317 if (ret) { 318 kdc_log(context, config, 0, "Can't open database for digest"); 319 goto out; 320 } 321 322 ret = krb5_rd_req(context, 323 &ac, 324 &req->authenticator, 325 NULL, 326 id, 327 &ap_req_options, 328 &ticket); 329 if (ret) 330 goto out; 331 332 ret = krb5_ticket_get_client(context, ticket, &cprincipal); 333 if (ret) 334 goto out; 335 336 ret = krb5_unparse_name(context, cprincipal, &cname); 337 if (ret) 338 goto out; 339 340 /* verify server principal */ 341 342 ret = krb5_sname_to_principal(context, NULL, "kca_service", 343 KRB5_NT_UNKNOWN, &sprincipal); 344 if (ret) 345 goto out; 346 347 { 348 krb5_principal principal = NULL; 349 350 ret = krb5_ticket_get_server(context, ticket, &principal); 351 if (ret) 352 goto out; 353 354 ret = krb5_principal_compare(context, sprincipal, principal); 355 krb5_free_principal(context, principal); 356 if (ret != TRUE) { 357 ret = KRB5KDC_ERR_SERVER_NOMATCH; 358 krb5_set_error_message(context, ret, 359 "User %s used wrong Kx509 service principal", 360 cname); 361 goto out; 362 } 363 } 364 365 ret = krb5_auth_con_getkey(context, ac, &key); 366 if (ret == 0 && key == NULL) 367 ret = KRB5KDC_ERR_NULL_KEY; 368 if (ret) { 369 krb5_set_error_message(context, ret, "Kx509 can't get session key"); 370 goto out; 371 } 372 373 ret = verify_req_hash(context, req, key); 374 if (ret) 375 goto out; 376 377 /* Verify that the key is encoded RSA key */ 378 { 379 RSAPublicKey key; 380 size_t size; 381 382 ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length, 383 &key, &size); 384 if (ret) 385 goto out; 386 free_RSAPublicKey(&key); 387 if (size != req->pk_key.length) { 388 ret = ASN1_EXTRA_DATA; 389 goto out; 390 } 391 } 392 393 ALLOC(rep.certificate); 394 if (rep.certificate == NULL) 395 goto out; 396 krb5_data_zero(rep.certificate); 397 ALLOC(rep.hash); 398 if (rep.hash == NULL) 399 goto out; 400 krb5_data_zero(rep.hash); 401 402 ret = build_certificate(context, config, &req->pk_key, 403 krb5_ticket_get_endtime(context, ticket), 404 cprincipal, rep.certificate); 405 if (ret) 406 goto out; 407 408 ret = calculate_reply_hash(context, key, &rep); 409 if (ret) 410 goto out; 411 412 /* 413 * Encode reply, [ version | Kx509Response ] 414 */ 415 416 { 417 krb5_data data; 418 419 ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep, 420 &size, ret); 421 if (ret) { 422 krb5_set_error_message(context, ret, "Failed to encode kx509 reply"); 423 goto out; 424 } 425 if (size != data.length) 426 krb5_abortx(context, "ASN1 internal error"); 427 428 ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0)); 429 if (ret) { 430 free(data.data); 431 goto out; 432 } 433 memcpy(reply->data, version_2_0, sizeof(version_2_0)); 434 memcpy(((unsigned char *)reply->data) + sizeof(version_2_0), 435 data.data, data.length); 436 free(data.data); 437 } 438 439 kdc_log(context, config, 0, "Successful Kx509 request for %s", cname); 440 441out: 442 if (ac) 443 krb5_auth_con_free(context, ac); 444 if (ret) 445 krb5_warn(context, ret, "Kx509 request from %s failed", from); 446 if (ticket) 447 krb5_free_ticket(context, ticket); 448 if (id) 449 krb5_kt_close(context, id); 450 if (sprincipal) 451 krb5_free_principal(context, sprincipal); 452 if (cprincipal) 453 krb5_free_principal(context, cprincipal); 454 if (key) 455 krb5_free_keyblock (context, key); 456 if (cname) 457 free(cname); 458 free_Kx509Response(&rep); 459 460 return 0; 461} 462 463#endif /* KX509 */ 464