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 RCSID("$Id: kx509.c 21607 2007-07-17 07:04:52Z lha $"); 40 41 /* 42 * 43 */ 44 45 krb5_error_code 46 _kdc_try_kx509_request(void *ptr, size_t len, 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_string(context, "pk-hash have wrong length: %lu", 71 (unsigned long)req->pk_hash.length); 72 return KRB5KDC_ERR_PREAUTH_FAILED; 73 } 74 75 HMAC_CTX_init(&ctx); 76 HMAC_Init_ex(&ctx, 77 key->keyvalue.data, key->keyvalue.length, 78 EVP_sha1(), NULL); 79 if (sizeof(digest) != HMAC_size(&ctx)) 80 krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509"); 81 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 82 HMAC_Update(&ctx, req->pk_key.data, req->pk_key.length); 83 HMAC_Final(&ctx, digest, 0); 84 HMAC_CTX_cleanup(&ctx); 85 86 if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) { 87 krb5_set_error_string(context, "pk-hash is not correct"); 88 return KRB5KDC_ERR_PREAUTH_FAILED; 89 } 90 return 0; 91 } 92 93 static krb5_error_code 94 calculate_reply_hash(krb5_context context, 95 krb5_keyblock *key, 96 Kx509Response *rep) 97 { 98 HMAC_CTX ctx; 99 100 HMAC_CTX_init(&ctx); 101 102 HMAC_Init_ex(&ctx, 103 key->keyvalue.data, key->keyvalue.length, 104 EVP_sha1(), NULL); 105 rep->hash->length = HMAC_size(&ctx); 106 rep->hash->data = malloc(rep->hash->length); 107 if (rep->hash->data == NULL) { 108 HMAC_CTX_cleanup(&ctx); 109 krb5_set_error_string(context, "out of memory"); 110 return ENOMEM; 111 } 112 113 HMAC_Update(&ctx, version_2_0, sizeof(version_2_0)); 114 if (rep->error_code) { 115 int32_t t = *rep->error_code; 116 do { 117 unsigned char p = (t & 0xff); 118 HMAC_Update(&ctx, &p, 1); 119 t >>= 8; 120 } while (t); 121 } 122 if (rep->certificate) 123 HMAC_Update(&ctx, rep->certificate->data, rep->certificate->length); 124 if (rep->e_text) 125 HMAC_Update(&ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text)); 126 127 HMAC_Final(&ctx, rep->hash->data, 0); 128 HMAC_CTX_cleanup(&ctx); 129 130 return 0; 131 } 132 133 /* 134 * Build a certifate for `principal� that will expire at `endtime�. 135 */ 136 137 static krb5_error_code 138 build_certificate(krb5_context context, 139 krb5_kdc_configuration *config, 140 const krb5_data *key, 141 time_t endtime, 142 krb5_principal principal, 143 krb5_data *certificate) 144 { 145 hx509_context hxctx = NULL; 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_context_init(&hxctx); 158 if (ret) 159 goto out; 160 161 ret = hx509_env_init(hxctx, &env); 162 if (ret) 163 goto out; 164 165 ret = hx509_env_add(hxctx, env, "principal-name", 166 krb5_principal_get_comp_string(context, principal, 0)); 167 if (ret) 168 goto out; 169 170 { 171 hx509_certs certs; 172 hx509_query *q; 173 174 ret = hx509_certs_init(hxctx, config->kx509_ca, 0, 175 NULL, &certs); 176 if (ret) { 177 kdc_log(context, config, 0, "Failed to load CA %s", 178 config->kx509_ca); 179 goto out; 180 } 181 ret = hx509_query_alloc(hxctx, &q); 182 if (ret) { 183 hx509_certs_free(&certs); 184 goto out; 185 } 186 187 hx509_query_match_option(q, HX509_QUERY_OPTION_PRIVATE_KEY); 188 hx509_query_match_option(q, HX509_QUERY_OPTION_KU_KEYCERTSIGN); 189 190 ret = hx509_certs_find(hxctx, certs, q, &signer); 191 hx509_query_free(hxctx, q); 192 hx509_certs_free(&certs); 193 if (ret) { 194 kdc_log(context, config, 0, "Failed to find a CA in %s", 195 config->kx509_ca); 196 goto out; 197 } 198 } 199 200 ret = hx509_ca_tbs_init(hxctx, &tbs); 201 if (ret) 202 goto out; 203 204 { 205 SubjectPublicKeyInfo spki; 206 heim_any any; 207 208 memset(&spki, 0, sizeof(spki)); 209 210 spki.subjectPublicKey.data = key->data; 211 spki.subjectPublicKey.length = key->length * 8; 212 213 ret = der_copy_oid(oid_id_pkcs1_rsaEncryption(), 214 &spki.algorithm.algorithm); 215 216 any.data = "\x05\x00"; 217 any.length = 2; 218 spki.algorithm.parameters = &any; 219 220 ret = hx509_ca_tbs_set_spki(hxctx, tbs, &spki); 221 der_free_oid(&spki.algorithm.algorithm); 222 if (ret) 223 goto out; 224 } 225 226 { 227 hx509_certs certs; 228 hx509_cert template; 229 230 ret = hx509_certs_init(hxctx, config->kx509_template, 0, 231 NULL, &certs); 232 if (ret) { 233 kdc_log(context, config, 0, "Failed to load template %s", 234 config->kx509_template); 235 goto out; 236 } 237 ret = hx509_get_one_cert(hxctx, certs, &template); 238 hx509_certs_free(&certs); 239 if (ret) { 240 kdc_log(context, config, 0, "Failed to find template in %s", 241 config->kx509_template); 242 goto out; 243 } 244 ret = hx509_ca_tbs_set_template(hxctx, tbs, 245 HX509_CA_TEMPLATE_SUBJECT| 246 HX509_CA_TEMPLATE_KU| 247 HX509_CA_TEMPLATE_EKU, 248 template); 249 hx509_cert_free(template); 250 if (ret) 251 goto out; 252 } 253 254 hx509_ca_tbs_set_notAfter(hxctx, tbs, endtime); 255 256 hx509_ca_tbs_subject_expand(hxctx, tbs, env); 257 hx509_env_free(&env); 258 259 ret = hx509_ca_sign(hxctx, tbs, signer, &cert); 260 hx509_cert_free(signer); 261 if (ret) 262 goto out; 263 264 hx509_ca_tbs_free(&tbs); 265 266 ret = hx509_cert_binary(hxctx, cert, certificate); 267 hx509_cert_free(cert); 268 if (ret) 269 goto out; 270 271 hx509_context_free(&hxctx); 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 if (hxctx) 282 hx509_context_free(&hxctx); 283 krb5_set_error_string(context, "cert creation failed"); 284 return ret; 285 } 286 287 /* 288 * 289 */ 290 291 krb5_error_code 292 _kdc_do_kx509(krb5_context context, 293 krb5_kdc_configuration *config, 294 const Kx509Request *req, krb5_data *reply, 295 const char *from, struct sockaddr *addr) 296 { 297 krb5_error_code ret; 298 krb5_ticket *ticket = NULL; 299 krb5_flags ap_req_options; 300 krb5_auth_context ac = NULL; 301 krb5_keytab id = NULL; 302 krb5_principal sprincipal = NULL, cprincipal = NULL; 303 char *cname = NULL; 304 Kx509Response rep; 305 size_t size; 306 krb5_keyblock *key = NULL; 307 308 krb5_data_zero(reply); 309 memset(&rep, 0, sizeof(rep)); 310 311 if(!config->enable_kx509) { 312 kdc_log(context, config, 0, 313 "Rejected kx509 request (disabled) from %s", from); 314 return KRB5KDC_ERR_POLICY; 315 } 316 317 kdc_log(context, config, 0, "Kx509 request from %s", from); 318 319 ret = krb5_kt_resolve(context, "HDB:", &id); 320 if (ret) { 321 kdc_log(context, config, 0, "Can't open database for digest"); 322 goto out; 323 } 324 325 ret = krb5_rd_req(context, 326 &ac, 327 &req->authenticator, 328 NULL, 329 id, 330 &ap_req_options, 331 &ticket); 332 if (ret) 333 goto out; 334 335 ret = krb5_ticket_get_client(context, ticket, &cprincipal); 336 if (ret) 337 goto out; 338 339 ret = krb5_unparse_name(context, cprincipal, &cname); 340 if (ret) 341 goto out; 342 343 /* verify server principal */ 344 345 ret = krb5_sname_to_principal(context, NULL, "kca_service", 346 KRB5_NT_UNKNOWN, &sprincipal); 347 if (ret) 348 goto out; 349 350 { 351 krb5_principal principal = NULL; 352 353 ret = krb5_ticket_get_server(context, ticket, &principal); 354 if (ret) 355 goto out; 356 357 ret = krb5_principal_compare(context, sprincipal, principal); 358 krb5_free_principal(context, principal); 359 if (ret != TRUE) { 360 ret = KRB5KDC_ERR_SERVER_NOMATCH; 361 krb5_set_error_string(context, 362 "User %s used wrong Kx509 service principal", 363 cname); 364 goto out; 365 } 366 } 367 368 ret = krb5_auth_con_getkey(context, ac, &key); 369 if (ret || key == NULL) { 370 krb5_set_error_string(context, "Kx509 can't get session key"); 371 goto out; 372 } 373 374 ret = verify_req_hash(context, req, key); 375 if (ret) 376 goto out; 377 378 /* Verify that the key is encoded RSA key */ 379 { 380 RSAPublicKey key; 381 size_t size; 382 383 ret = decode_RSAPublicKey(req->pk_key.data, req->pk_key.length, 384 &key, &size); 385 if (ret) 386 goto out; 387 free_RSAPublicKey(&key); 388 if (size != req->pk_key.length) 389 ; 390 } 391 392 ALLOC(rep.certificate); 393 if (rep.certificate == NULL) 394 goto out; 395 krb5_data_zero(rep.certificate); 396 ALLOC(rep.hash); 397 if (rep.hash == NULL) 398 goto out; 399 krb5_data_zero(rep.hash); 400 401 ret = build_certificate(context, config, &req->pk_key, 402 krb5_ticket_get_endtime(context, ticket), 403 cprincipal, rep.certificate); 404 if (ret) 405 goto out; 406 407 ret = calculate_reply_hash(context, key, &rep); 408 if (ret) 409 goto out; 410 411 /* 412 * Encode reply, [ version | Kx509Response ] 413 */ 414 415 { 416 krb5_data data; 417 418 ASN1_MALLOC_ENCODE(Kx509Response, data.data, data.length, &rep, 419 &size, ret); 420 if (ret) { 421 krb5_set_error_string(context, "Failed to encode kx509 reply"); 422 goto out; 423 } 424 if (size != data.length) 425 krb5_abortx(context, "ASN1 internal error"); 426 427 ret = krb5_data_alloc(reply, data.length + sizeof(version_2_0)); 428 if (ret) { 429 free(data.data); 430 goto out; 431 } 432 memcpy(reply->data, version_2_0, sizeof(version_2_0)); 433 memcpy(((unsigned char *)reply->data) + sizeof(version_2_0), 434 data.data, data.length); 435 free(data.data); 436 } 437 438 kdc_log(context, config, 0, "Successful Kx509 request for %s", cname); 439 440 out: 441 if (ac) 442 krb5_auth_con_free(context, ac); 443 if (ret) 444 krb5_warn(context, ret, "Kx509 request from %s failed", from); 445 if (ticket) 446 krb5_free_ticket(context, ticket); 447 if (id) 448 krb5_kt_close(context, id); 449 if (sprincipal) 450 krb5_free_principal(context, sprincipal); 451 if (cprincipal) 452 krb5_free_principal(context, cprincipal); 453 if (key) 454 krb5_free_keyblock (context, key); 455 if (cname) 456 free(cname); 457 free_Kx509Response(&rep); 458 459 return 0; 460 } 461