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 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 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 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 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 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