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 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 95 static krb5_error_code 96 calculate_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 */ 137 138 static krb5_error_code 139 build_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_ca_tbs tbs = NULL; 147 hx509_env env = NULL; 148 hx509_cert cert = NULL; 149 hx509_cert signer = NULL; 150 int ret; 151 152 if (krb5_principal_get_comp_string(context, principal, 1) != NULL) { 153 kdc_log(context, config, 0, "Principal is not a user"); 154 return EINVAL; 155 } 156 157 ret = hx509_env_add(context->hx509ctx, &env, "principal-name", 158 krb5_principal_get_comp_string(context, principal, 0)); 159 if (ret) 160 goto out; 161 162 { 163 hx509_certs certs; 164 hx509_query *q; 165 166 ret = hx509_certs_init(context->hx509ctx, config->kx509_ca, 0, 167 NULL, &certs); 168 if (ret) { 169 kdc_log(context, config, 0, "Failed to load CA %s", 170 config->kx509_ca); 171 goto out; 172 } 173 ret = hx509_query_alloc(context->hx509ctx, &q); 174 if (ret) { 175 hx509_certs_free(&certs); 176 goto out; 177 } 178 179 hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY); 180 hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN); 181 182 ret = hx509_certs_find(context->hx509ctx, certs, q, &signer); 183 hx509_query_free(context->hx509ctx, q); 184 hx509_certs_free(&certs); 185 if (ret) { 186 kdc_log(context, config, 0, "Failed to find a CA in %s", 187 config->kx509_ca); 188 goto out; 189 } 190 } 191 192 ret = hx509_ca_tbs_init(context->hx509ctx, &tbs); 193 if (ret) 194 goto out; 195 196 { 197 SubjectPublicKeyInfo spki; 198 heim_any any; 199 200 memset(&spki, 0, sizeof(spki)); 201 202 spki.subjectPublicKey.data = key->data; 203 spki.subjectPublicKey.length = key->length * 8; 204 205 ret = der_copy_oid(&asn1_oid_id_pkcs1_rsaEncryption, 206 &spki.algorithm.algorithm); 207 208 any.data = "\x05\x00"; 209 any.length = 2; 210 spki.algorithm.parameters = &any; 211 212 ret = hx509_ca_tbs_set_spki(context->hx509ctx, tbs, &spki); 213 der_free_oid(&spki.algorithm.algorithm); 214 if (ret) 215 goto out; 216 } 217 218 { 219 hx509_certs certs; 220 hx509_cert template; 221 222 ret = hx509_certs_init(context->hx509ctx, config->kx509_template, 0, 223 NULL, &certs); 224 if (ret) { 225 kdc_log(context, config, 0, "Failed to load template %s", 226 config->kx509_template); 227 goto out; 228 } 229 ret = hx509_get_one_cert(context->hx509ctx, certs, &template); 230 hx509_certs_free(&certs); 231 if (ret) { 232 kdc_log(context, config, 0, "Failed to find template in %s", 233 config->kx509_template); 234 goto out; 235 } 236 ret = hx509_ca_tbs_set_template(context->hx509ctx, tbs, 237 HX509_CA_TEMPLATE_SUBJECT| 238 HX509_CA_TEMPLATE_KU| 239 HX509_CA_TEMPLATE_EKU, 240 template); 241 hx509_cert_free(template); 242 if (ret) 243 goto out; 244 } 245 246 hx509_ca_tbs_set_notAfter(context->hx509ctx, tbs, endtime); 247 248 hx509_ca_tbs_subject_expand(context->hx509ctx, tbs, env); 249 hx509_env_free(&env); 250 251 ret = hx509_ca_sign(context->hx509ctx, tbs, signer, &cert); 252 hx509_cert_free(signer); 253 if (ret) 254 goto out; 255 256 hx509_ca_tbs_free(&tbs); 257 258 ret = hx509_cert_binary(context->hx509ctx, cert, certificate); 259 hx509_cert_free(cert); 260 if (ret) 261 goto out; 262 263 return 0; 264 out: 265 if (env) 266 hx509_env_free(&env); 267 if (tbs) 268 hx509_ca_tbs_free(&tbs); 269 if (signer) 270 hx509_cert_free(signer); 271 krb5_set_error_message(context, ret, "cert creation failed"); 272 return ret; 273 } 274 275 /* 276 * 277 */ 278 279 krb5_error_code 280 _kdc_do_kx509(krb5_context context, 281 krb5_kdc_configuration *config, 282 const struct Kx509Request *req, krb5_data *reply, 283 const char *from, struct sockaddr *addr) 284 { 285 krb5_error_code ret; 286 krb5_ticket *ticket = NULL; 287 krb5_flags ap_req_options; 288 krb5_auth_context ac = NULL; 289 krb5_keytab id = NULL; 290 krb5_principal sprincipal = NULL, cprincipal = NULL; 291 char *cname = NULL; 292 Kx509Response rep; 293 size_t size; 294 krb5_keyblock *key = NULL; 295 296 krb5_data_zero(reply); 297 memset(&rep, 0, sizeof(rep)); 298 299 if(!config->enable_kx509) { 300 kdc_log(context, config, 0, 301 "Rejected kx509 request (disabled) from %s", from); 302 return KRB5KDC_ERR_POLICY; 303 } 304 305 kdc_log(context, config, 0, "Kx509 request from %s", from); 306 307 ret = krb5_kt_resolve(context, "HDB:", &id); 308 if (ret) { 309 kdc_log(context, config, 0, "Can't open database for digest"); 310 goto out; 311 } 312 313 ret = krb5_rd_req(context, 314 &ac, 315 &req->authenticator, 316 NULL, 317 id, 318 &ap_req_options, 319 &ticket); 320 if (ret) 321 goto out; 322 323 ret = krb5_ticket_get_client(context, ticket, &cprincipal); 324 if (ret) 325 goto out; 326 327 ret = krb5_unparse_name(context, cprincipal, &cname); 328 if (ret) 329 goto out; 330 331 /* verify server principal */ 332 333 ret = krb5_sname_to_principal(context, NULL, "kca_service", 334 KRB5_NT_UNKNOWN, &sprincipal); 335 if (ret) 336 goto out; 337 338 { 339 krb5_principal principal = NULL; 340 341 ret = krb5_ticket_get_server(context, ticket, &principal); 342 if (ret) 343 goto out; 344 345 ret = krb5_principal_compare(context, sprincipal, principal); 346 krb5_free_principal(context, principal); 347 if (ret != TRUE) { 348 char *expected, *used; 349 350 ret = krb5_unparse_name(context, sprincipal, &expected); 351 if (ret) 352 goto out; 353 ret = krb5_unparse_name(context, principal, &used); 354 if (ret) { 355 krb5_xfree(expected); 356 goto out; 357 } 358 359 ret = KRB5KDC_ERR_SERVER_NOMATCH; 360 krb5_set_error_message(context, ret, 361 "User %s used wrong Kx509 service " 362 "principal, expected: %s, used %s", 363 cname, expected, used); 364 krb5_xfree(expected); 365 krb5_xfree(used); 366 goto out; 367 } 368 } 369 370 ret = krb5_auth_con_getkey(context, ac, &key); 371 if (ret == 0 && key == NULL) 372 ret = KRB5KDC_ERR_NULL_KEY; 373 if (ret) { 374 krb5_set_error_message(context, ret, "Kx509 can't get session key"); 375 goto out; 376 } 377 378 ret = verify_req_hash(context, req, key); 379 if (ret) 380 goto out; 381 382 /* Verify that the key is encoded RSA key */ 383 { 384 RSAPublicKey key; 385 size_t size; 386 387 ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length, 388 &key, &size); 389 if (ret) 390 goto out; 391 free_RSAPublicKey(&key); 392 if (size != req->pk_key.length) { 393 ret = ASN1_EXTRA_DATA; 394 goto out; 395 } 396 } 397 398 ALLOC(rep.certificate); 399 if (rep.certificate == NULL) 400 goto out; 401 krb5_data_zero(rep.certificate); 402 ALLOC(rep.hash); 403 if (rep.hash == NULL) 404 goto out; 405 krb5_data_zero(rep.hash); 406 407 ret = build_certificate(context, config, &req->pk_key, 408 krb5_ticket_get_endtime(context, ticket), 409 cprincipal, rep.certificate); 410 if (ret) 411 goto out; 412 413 ret = calculate_reply_hash(context, key, &rep); 414 if (ret) 415 goto out; 416 417 /* 418 * Encode reply, [ version | Kx509Response ] 419 */ 420 421 { 422 krb5_data data; 423 424 ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep, 425 &size, ret); 426 if (ret) { 427 krb5_set_error_message(context, ret, "Failed to encode kx509 reply"); 428 goto out; 429 } 430 if (size != data.length) 431 krb5_abortx(context, "ASN1 internal error"); 432 433 ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0)); 434 if (ret) { 435 free(data.data); 436 goto out; 437 } 438 memcpy(reply->data, version_2_0, sizeof(version_2_0)); 439 memcpy(((unsigned char *)reply->data) + sizeof(version_2_0), 440 data.data, data.length); 441 free(data.data); 442 } 443 444 kdc_log(context, config, 0, "Successful Kx509 request for %s", cname); 445 446 out: 447 if (ac) 448 krb5_auth_con_free(context, ac); 449 if (ret) 450 krb5_warn(context, ret, "Kx509 request from %s failed", from); 451 if (ticket) 452 krb5_free_ticket(context, ticket); 453 if (id) 454 krb5_kt_close(context, id); 455 if (sprincipal) 456 krb5_free_principal(context, sprincipal); 457 if (cprincipal) 458 krb5_free_principal(context, cprincipal); 459 if (key) 460 krb5_free_keyblock (context, key); 461 if (cname) 462 free(cname); 463 free_Kx509Response(&rep); 464 465 return 0; 466 } 467 468 #endif /* KX509 */ 469