1/* $NetBSD$ */ 2 3/* 4 * Copyright (c) 2006 - 2007 Kungliga Tekniska H��gskolan 5 * (Royal Institute of Technology, Stockholm, Sweden). 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * 3. Neither the name of the Institute nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36#include "kdc_locl.h" 37#include <krb5/hex.h> 38#include <krb5/rfc2459_asn1.h> 39#include <krb5/hx509.h> 40 41#ifdef KX509 42 43/* 44 * 45 */ 46 47krb5_error_code 48_kdc_try_kx509_request(void *ptr, size_t len, struct Kx509Request *req, size_t *size) 49{ 50 if (len < 4) 51 return -1; 52 if (memcmp("\x00\x00\x02\x00", ptr, 4) != 0) 53 return -1; 54 return decode_Kx509Request(((unsigned char *)ptr) + 4, len - 4, req, size); 55} 56 57/* 58 * 59 */ 60 61static const unsigned char version_2_0[4] = {0 , 0, 2, 0}; 62 63static krb5_error_code 64verify_req_hash(krb5_context context, 65 const Kx509Request *req, 66 krb5_keyblock *key) 67{ 68 unsigned char digest[SHA_DIGEST_LENGTH]; 69 HMAC_CTX ctx; 70 71 if (req->pk_hash.length != sizeof(digest)) { 72 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED, 73 "pk-hash have wrong length: %lu", 74 (unsigned long)req->pk_hash.length); 75 return KRB5KDC_ERR_PREAUTH_FAILED; 76 } 77 78 HMAC_CTX_init(&ctx); 79 HMAC_Init_ex(&ctx, 80 key->keyvalue.data, key->keyvalue.length, 81 EVP_sha1(), NULL); 82 if (sizeof(digest) != HMAC_size(&ctx)) 83 krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509"); 84 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 85 HMAC_Update(&ctx, req->pk_key.data, req->pk_key.length); 86 HMAC_Final(&ctx, digest, 0); 87 HMAC_CTX_cleanup(&ctx); 88 89 if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) { 90 krb5_set_error_message(context, KRB5KDC_ERR_PREAUTH_FAILED, 91 "pk-hash is not correct"); 92 return KRB5KDC_ERR_PREAUTH_FAILED; 93 } 94 return 0; 95} 96 97static krb5_error_code 98calculate_reply_hash(krb5_context context, 99 krb5_keyblock *key, 100 Kx509Response *rep) 101{ 102 krb5_error_code ret; 103 HMAC_CTX ctx; 104 105 HMAC_CTX_init(&ctx); 106 107 HMAC_Init_ex(&ctx, key->keyvalue.data, key->keyvalue.length, 108 EVP_sha1(), NULL); 109 ret = krb5_data_alloc(rep->hash, HMAC_size(&ctx)); 110 if (ret) { 111 HMAC_CTX_cleanup(&ctx); 112 krb5_set_error_message(context, ENOMEM, "malloc: out of memory"); 113 return ENOMEM; 114 } 115 116 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 117 if (rep->error_code) { 118 int32_t t = *rep->error_code; 119 do { 120 unsigned char p = (t & 0xff); 121 HMAC_Update(&ctx, &p, 1); 122 t >>= 8; 123 } while (t); 124 } 125 if (rep->certificate) 126 HMAC_Update(&ctx, rep->certificate->data, rep->certificate->length); 127 if (rep->e_text) 128 HMAC_Update(&ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text)); 129 130 HMAC_Final(&ctx, rep->hash->data, 0); 131 HMAC_CTX_cleanup(&ctx); 132 133 return 0; 134} 135 136/* 137 * Build a certifate for `principal�� that will expire at `endtime��. 138 */ 139 140static krb5_error_code 141build_certificate(krb5_context context, 142 krb5_kdc_configuration *config, 143 const krb5_data *key, 144 time_t endtime, 145 krb5_principal principal, 146 krb5_data *certificate) 147{ 148 hx509_ca_tbs tbs = NULL; 149 hx509_env env = NULL; 150 hx509_cert cert = NULL; 151 hx509_cert signer = NULL; 152 int ret; 153 154 if (krb5_principal_get_comp_string(context, principal, 1) != NULL) { 155 kdc_log(context, config, 0, "Principal is not a user"); 156 return EINVAL; 157 } 158 159 ret = hx509_env_add(context->hx509ctx, &env, "principal-name", 160 krb5_principal_get_comp_string(context, principal, 0)); 161 if (ret) 162 goto out; 163 164 { 165 hx509_certs certs; 166 hx509_query *q; 167 168 ret = hx509_certs_init(context->hx509ctx, config->kx509_ca, 0, 169 NULL, &certs); 170 if (ret) { 171 kdc_log(context, config, 0, "Failed to load CA %s", 172 config->kx509_ca); 173 goto out; 174 } 175 ret = hx509_query_alloc(context->hx509ctx, &q); 176 if (ret) { 177 hx509_certs_free(&certs); 178 goto out; 179 } 180 181 hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY); 182 hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN); 183 184 ret = hx509_certs_find(context->hx509ctx, certs, q, &signer); 185 hx509_query_free(context->hx509ctx, q); 186 hx509_certs_free(&certs); 187 if (ret) { 188 kdc_log(context, config, 0, "Failed to find a CA in %s", 189 config->kx509_ca); 190 goto out; 191 } 192 } 193 194 ret = hx509_ca_tbs_init(context->hx509ctx, &tbs); 195 if (ret) 196 goto out; 197 198 { 199 SubjectPublicKeyInfo spki; 200 heim_any any; 201 202 memset(&spki, 0, sizeof(spki)); 203 204 spki.subjectPublicKey.data = key->data; 205 spki.subjectPublicKey.length = key->length * 8; 206 207 ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption, 208 &spki.algorithm.algorithm); 209 210 any.data = "\x05\x00"; 211 any.length = 2; 212 spki.algorithm.parameters = &any; 213 214 ret = hx509_ca_tbs_set_spki(context->hx509ctx, tbs, &spki); 215 der_free_oid(&spki.algorithm.algorithm); 216 if (ret) 217 goto out; 218 } 219 220 { 221 hx509_certs certs; 222 hx509_cert template; 223 224 ret = hx509_certs_init(context->hx509ctx, config->kx509_template, 0, 225 NULL, &certs); 226 if (ret) { 227 kdc_log(context, config, 0, "Failed to load template %s", 228 config->kx509_template); 229 goto out; 230 } 231 ret = hx509_get_one_cert(context->hx509ctx, certs, &template); 232 hx509_certs_free(&certs); 233 if (ret) { 234 kdc_log(context, config, 0, "Failed to find template in %s", 235 config->kx509_template); 236 goto out; 237 } 238 ret = hx509_ca_tbs_set_template(context->hx509ctx, tbs, 239 HX509_CA_TEMPLATE_SUBJECT| 240 HX509_CA_TEMPLATE_KU| 241 HX509_CA_TEMPLATE_EKU, 242 template); 243 hx509_cert_free(template); 244 if (ret) 245 goto out; 246 } 247 248 hx509_ca_tbs_set_notAfter(context->hx509ctx, tbs, endtime); 249 250 hx509_ca_tbs_subject_expand(context->hx509ctx, tbs, env); 251 hx509_env_free(&env); 252 253 ret = hx509_ca_sign(context->hx509ctx, tbs, signer, &cert); 254 hx509_cert_free(signer); 255 if (ret) 256 goto out; 257 258 hx509_ca_tbs_free(&tbs); 259 260 ret = hx509_cert_binary(context->hx509ctx, cert, certificate); 261 hx509_cert_free(cert); 262 if (ret) 263 goto out; 264 265 return 0; 266out: 267 if (env) 268 hx509_env_free(&env); 269 if (tbs) 270 hx509_ca_tbs_free(&tbs); 271 if (signer) 272 hx509_cert_free(signer); 273 krb5_set_error_message(context, ret, "cert creation failed"); 274 return ret; 275} 276 277/* 278 * 279 */ 280 281krb5_error_code 282_kdc_do_kx509(krb5_context context, 283 krb5_kdc_configuration *config, 284 const struct Kx509Request *req, krb5_data *reply, 285 const char *from, struct sockaddr *addr) 286{ 287 krb5_error_code ret; 288 krb5_ticket *ticket = NULL; 289 krb5_flags ap_req_options; 290 krb5_auth_context ac = NULL; 291 krb5_keytab id = NULL; 292 krb5_principal sprincipal = NULL, cprincipal = NULL; 293 char *cname = NULL; 294 Kx509Response rep; 295 size_t size; 296 krb5_keyblock *key = NULL; 297 298 krb5_data_zero(reply); 299 memset(&rep, 0, sizeof(rep)); 300 301 if(!config->enable_kx509) { 302 kdc_log(context, config, 0, 303 "Rejected kx509 request (disabled) from %s", from); 304 return KRB5KDC_ERR_POLICY; 305 } 306 307 kdc_log(context, config, 0, "Kx509 request from %s", from); 308 309 ret = krb5_kt_resolve(context, "HDB:", &id); 310 if (ret) { 311 kdc_log(context, config, 0, "Can't open database for digest"); 312 goto out; 313 } 314 315 ret = krb5_rd_req(context, 316 &ac, 317 &req->authenticator, 318 NULL, 319 id, 320 &ap_req_options, 321 &ticket); 322 if (ret) 323 goto out; 324 325 ret = krb5_ticket_get_client(context, ticket, &cprincipal); 326 if (ret) 327 goto out; 328 329 ret = krb5_unparse_name(context, cprincipal, &cname); 330 if (ret) 331 goto out; 332 333 /* verify server principal */ 334 335 ret = krb5_sname_to_principal(context, NULL, "kca_service", 336 KRB5_NT_UNKNOWN, &sprincipal); 337 if (ret) 338 goto out; 339 340 { 341 krb5_principal principal = NULL; 342 343 ret = krb5_ticket_get_server(context, ticket, &principal); 344 if (ret) 345 goto out; 346 347 ret = krb5_principal_compare(context, sprincipal, principal); 348 krb5_free_principal(context, principal); 349 if (ret != TRUE) { 350 char *expected, *used; 351 352 ret = krb5_unparse_name(context, sprincipal, &expected); 353 if (ret) 354 goto out; 355 ret = krb5_unparse_name(context, principal, &used); 356 if (ret) { 357 krb5_xfree(expected); 358 goto out; 359 } 360 361 ret = KRB5KDC_ERR_SERVER_NOMATCH; 362 krb5_set_error_message(context, ret, 363 "User %s used wrong Kx509 service " 364 "principal, expected: %s, used %s", 365 cname, expected, used); 366 krb5_xfree(expected); 367 krb5_xfree(used); 368 goto out; 369 } 370 } 371 372 ret = krb5_auth_con_getkey(context, ac, &key); 373 if (ret == 0 && key == NULL) 374 ret = KRB5KDC_ERR_NULL_KEY; 375 if (ret) { 376 krb5_set_error_message(context, ret, "Kx509 can't get session key"); 377 goto out; 378 } 379 380 ret = verify_req_hash(context, req, key); 381 if (ret) 382 goto out; 383 384 /* Verify that the key is encoded RSA key */ 385 { 386 RSAPublicKey key; 387 size_t size; 388 389 ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length, 390 &key, &size); 391 if (ret) 392 goto out; 393 free_RSAPublicKey(&key); 394 if (size != req->pk_key.length) { 395 ret = ASN1_EXTRA_DATA; 396 goto out; 397 } 398 } 399 400 ALLOC(rep.certificate); 401 if (rep.certificate == NULL) 402 goto out; 403 krb5_data_zero(rep.certificate); 404 ALLOC(rep.hash); 405 if (rep.hash == NULL) 406 goto out; 407 krb5_data_zero(rep.hash); 408 409 ret = build_certificate(context, config, &req->pk_key, 410 krb5_ticket_get_endtime(context, ticket), 411 cprincipal, rep.certificate); 412 if (ret) 413 goto out; 414 415 ret = calculate_reply_hash(context, key, &rep); 416 if (ret) 417 goto out; 418 419 /* 420 * Encode reply, [ version | Kx509Response ] 421 */ 422 423 { 424 krb5_data data; 425 426 ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep, 427 &size, ret); 428 if (ret) { 429 krb5_set_error_message(context, ret, "Failed to encode kx509 reply"); 430 goto out; 431 } 432 if (size != data.length) 433 krb5_abortx(context, "ASN1 internal error"); 434 435 ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0)); 436 if (ret) { 437 free(data.data); 438 goto out; 439 } 440 memcpy(reply->data, version_2_0, sizeof(version_2_0)); 441 memcpy(((unsigned char *)reply->data) + sizeof(version_2_0), 442 data.data, data.length); 443 free(data.data); 444 } 445 446 kdc_log(context, config, 0, "Successful Kx509 request for %s", cname); 447 448out: 449 if (ac) 450 krb5_auth_con_free(context, ac); 451 if (ret) 452 krb5_warn(context, ret, "Kx509 request from %s failed", from); 453 if (ticket) 454 krb5_free_ticket(context, ticket); 455 if (id) 456 krb5_kt_close(context, id); 457 if (sprincipal) 458 krb5_free_principal(context, sprincipal); 459 if (cprincipal) 460 krb5_free_principal(context, cprincipal); 461 if (key) 462 krb5_free_keyblock (context, key); 463 if (cname) 464 free(cname); 465 free_Kx509Response(&rep); 466 467 return 0; 468} 469 470#endif /* KX509 */ 471