moonshot/mech_eap/util_krb.c

   1 /*
   2  * Copyright (c) 2011, JANET(UK)
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * 3. Neither the name of JANET(UK) nor the names of its contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  21  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /*
  34  * Kerberos 5 helpers.
  35  */
  36
  37 #include "gssapiP_eap.h"
  38
  39 void
  40 gssEapDestroyKrbContext(krb5_context context)
  41 {
  42     if (context != NULL)
  43         krb5_free_context(context);
  44 }
  45
  46 static krb5_error_code
  47 initKrbContext(krb5_context *pKrbContext)
  48 {
  49     krb5_context krbContext;
  50     krb5_error_code code;
  51     char *defaultRealm = NULL;
  52
  53     *pKrbContext = NULL;
  54
  55     code = krb5_init_context(&krbContext);
  56     if (code != 0)
  57         goto cleanup;
  58
  59     krb5_appdefault_string(krbContext, "eap_gss",
  60                            NULL, "default_realm", "", &defaultRealm);
  61
  62     if (defaultRealm != NULL && defaultRealm[0] != '\0') {
  63         code = krb5_set_default_realm(krbContext, defaultRealm);
  64         if (code != 0)
  65             goto cleanup;
  66     }
  67
  68     *pKrbContext = krbContext;
  69
  70 cleanup:
  71     krb5_free_default_realm(krbContext, defaultRealm);
  72
  73     if (code != 0 && krbContext != NULL)
  74         krb5_free_context(krbContext);
  75
  76     return code;
  77 }
  78
  79 OM_uint32
  80 gssEapKerberosInit(OM_uint32 *minor, krb5_context *context)
  81 {
  82     struct gss_eap_thread_local_data *tld;
  83
  84     *minor = 0;
  85     *context = NULL;
  86
  87     tld = gssEapGetThreadLocalData();
  88     if (tld != NULL) {
  89         if (tld->krbContext == NULL) {
  90             *minor = initKrbContext(&tld->krbContext);
  91             if (*minor != 0)
  92                 tld->krbContext = NULL;
  93         }
  94         *context = tld->krbContext;
  95     } else {
  96         *minor = GSSEAP_GET_LAST_ERROR();
  97     }
  98
  99     GSSEAP_ASSERT(*context != NULL || *minor != 0);
 100
 101     return (*minor == 0) ? GSS_S_COMPLETE : GSS_S_FAILURE;
 102 }
 103
 104 /*
 105  * Derive a key K for RFC 4121 use by using the following
 106  * derivation function (based on RFC 4402);
 107  *
 108  * KMSK = random-to-key(MSK)
 109  * Tn = pseudo-random(KMSK, n || "rfc4121-gss-eap")
 110  * L = output key size
 111  * K = truncate(L, T1 || T2 || .. || Tn)
 112  */
 113 OM_uint32
 114 gssEapDeriveRfc3961Key(OM_uint32 *minor,
 115                        const unsigned char *inputKey,
 116                        size_t inputKeyLength,
 117                        krb5_enctype encryptionType,
 118                        krb5_keyblock *pKey)
 119 {
 120     krb5_context krbContext;
 121 #ifndef HAVE_HEIMDAL_VERSION
 122     krb5_data data;
 123 #endif
 124     krb5_data ns, t, prfOut;
 125     krb5_keyblock kd;
 126     krb5_error_code code;
 127     size_t randomLength, keyLength, prfLength;
 128     unsigned char constant[4 + sizeof("rfc4121-gss-eap") - 1], *p;
 129     ssize_t i, remain;
 130
 131     GSSEAP_ASSERT(encryptionType != ENCTYPE_NULL);
 132
 133     memset(pKey, 0, sizeof(*pKey));
 134
 135     GSSEAP_KRB_INIT(&krbContext);
 136
 137     KRB_KEY_INIT(&kd);
 138     KRB_KEY_TYPE(&kd) = encryptionType;
 139
 140     t.data = NULL;
 141     t.length = 0;
 142
 143     prfOut.data = NULL;
 144     prfOut.length = 0;
 145
 146     code = krb5_c_keylengths(krbContext, encryptionType,
 147                              &randomLength, &keyLength);
 148     if (code != 0)
 149         goto cleanup;
 150
 151     KRB_KEY_DATA(&kd) = GSSEAP_MALLOC(keyLength);
 152     if (KRB_KEY_DATA(&kd) == NULL) {
 153         code = ENOMEM;
 154         goto cleanup;
 155     }
 156     KRB_KEY_LENGTH(&kd) = keyLength;
 157
 158     /* Convert MSK into a Kerberos key */
 159 #ifdef HAVE_HEIMDAL_VERSION
 160     code = krb5_random_to_key(krbContext, encryptionType, inputKey,
 161                               MIN(inputKeyLength, randomLength), &kd);
 162 #else
 163     data.length = MIN(inputKeyLength, randomLength);
 164     data.data = (char *)inputKey;
 165
 166     code = krb5_c_random_to_key(krbContext, encryptionType, &data, &kd);
 167 #endif
 168     if (code != 0)
 169         goto cleanup;
 170
 171     memset(&constant[0], 0, 4);
 172     memcpy(&constant[4], "rfc4121-gss-eap", sizeof("rfc4121-gss-eap") - 1);
 173
 174     ns.length = sizeof(constant);
 175     ns.data = (char *)constant;
 176
 177     /* Plug derivation constant and key into PRF */
 178     code = krb5_c_prf_length(krbContext, encryptionType, &prfLength);
 179     if (code != 0)
 180         goto cleanup;
 181
 182     t.length = prfLength;
 183     t.data = GSSEAP_MALLOC(t.length);
 184     if (t.data == NULL) {
 185         code = ENOMEM;
 186         goto cleanup;
 187     }
 188
 189     prfOut.length = randomLength;
 190     prfOut.data = GSSEAP_MALLOC(prfOut.length);
 191     if (prfOut.data == NULL) {
 192         code = ENOMEM;
 193         goto cleanup;
 194     }
 195
 196     for (i = 0, p = (unsigned char *)prfOut.data, remain = randomLength;
 197          remain > 0;
 198          p += t.length, remain -= t.length, i++)
 199     {
 200         store_uint32_be(i, ns.data);
 201
 202         code = krb5_c_prf(krbContext, &kd, &ns, &t);
 203         if (code != 0)
 204             goto cleanup;
 205
 206         memcpy(p, t.data, MIN(t.length, remain));
 207      }
 208
 209     /* Finally, convert PRF output into a new key which we will return */
 210 #ifdef HAVE_HEIMDAL_VERSION
 211     code = krb5_random_to_key(krbContext, encryptionType,
 212                               prfOut.data, prfOut.length, &kd);
 213 #else
 214     code = krb5_c_random_to_key(krbContext, encryptionType, &prfOut, &kd);
 215 #endif
 216     if (code != 0)
 217         goto cleanup;
 218
 219     *pKey = kd;
 220     KRB_KEY_DATA(&kd) = NULL;
 221
 222 cleanup:
 223     if (KRB_KEY_DATA(&kd) != NULL) {
 224         memset(KRB_KEY_DATA(&kd), 0, KRB_KEY_LENGTH(&kd));
 225         GSSEAP_FREE(KRB_KEY_DATA(&kd));
 226     }
 227     if (t.data != NULL) {
 228         memset(t.data, 0, t.length);
 229         GSSEAP_FREE(t.data);
 230     }
 231     if (prfOut.data != NULL) {
 232         memset(prfOut.data, 0, prfOut.length);
 233         GSSEAP_FREE(prfOut.data);
 234     }
 235     *minor = code;
 236     return (code == 0) ? GSS_S_COMPLETE : GSS_S_FAILURE;
 237 }
 238
 239 #ifdef HAVE_KRB5INT_C_MANDATORY_CKSUMTYPE
 240 extern krb5_error_code
 241 krb5int_c_mandatory_cksumtype(krb5_context, krb5_enctype, krb5_cksumtype *);
 242 #endif
 243
 244 OM_uint32
 245 rfc3961ChecksumTypeForKey(OM_uint32 *minor,
 246                           krb5_keyblock *key,
 247                           krb5_cksumtype *cksumtype)
 248 {
 249     krb5_context krbContext;
 250 #ifndef HAVE_KRB5INT_C_MANDATORY_CKSUMTYPE
 251     krb5_data data;
 252     krb5_checksum cksum;
 253 #endif
 254
 255     GSSEAP_KRB_INIT(&krbContext);
 256
 257 #ifdef HAVE_KRB5INT_C_MANDATORY_CKSUMTYPE
 258     *minor = krb5int_c_mandatory_cksumtype(krbContext, KRB_KEY_TYPE(key),
 259                                            cksumtype);
 260     if (*minor != 0)
 261         return GSS_S_FAILURE;
 262 #else
 263     data.length = 0;
 264     data.data = NULL;
 265
 266     memset(&cksum, 0, sizeof(cksum));
 267
 268     /*
 269      * This is a complete hack but it's the only way to work with
 270      * MIT Kerberos pre-1.9 without using private API, as it does
 271      * not support passing in zero as the checksum type.
 272      */
 273     *minor = krb5_c_make_checksum(krbContext, 0, key, 0, &data, &cksum);
 274     if (*minor != 0)
 275         return GSS_S_FAILURE;
 276
 277 #ifdef HAVE_HEIMDAL_VERSION
 278     *cksumtype = cksum.cksumtype;
 279 #else
 280     *cksumtype = cksum.checksum_type;
 281 #endif
 282
 283     krb5_free_checksum_contents(krbContext, &cksum);
 284 #endif /* HAVE_KRB5INT_C_MANDATORY_CKSUMTYPE */
 285
 286     if (!krb5_c_is_keyed_cksum(*cksumtype)) {
 287         *minor = (OM_uint32)KRB5KRB_AP_ERR_INAPP_CKSUM;
 288         return GSS_S_FAILURE;
 289     }
 290
 291     return GSS_S_COMPLETE;
 292 }
 293
 294 krb5_error_code
 295 krbCryptoLength(krb5_context krbContext,
 296 #ifdef HAVE_HEIMDAL_VERSION
 297                 krb5_crypto krbCrypto,
 298 #else
 299                 krb5_keyblock *key,
 300 #endif
 301                 int type,
 302                 size_t *length)
 303 {
 304 #ifdef HAVE_HEIMDAL_VERSION
 305     return krb5_crypto_length(krbContext, krbCrypto, type, length);
 306 #else
 307     unsigned int len;
 308     krb5_error_code code;
 309
 310     code = krb5_c_crypto_length(krbContext, KRB_KEY_TYPE(key), type, &len);
 311     if (code == 0)
 312         *length = (size_t)len;
 313
 314     return code;
 315 #endif
 316 }
 317
 318 krb5_error_code
 319 krbPaddingLength(krb5_context krbContext,
 320 #ifdef HAVE_HEIMDAL_VERSION
 321                  krb5_crypto krbCrypto,
 322 #else
 323                  krb5_keyblock *key,
 324 #endif
 325                  size_t dataLength,
 326                  size_t *padLength)
 327 {
 328     krb5_error_code code;
 329 #ifdef HAVE_HEIMDAL_VERSION
 330     size_t headerLength, paddingLength;
 331
 332     code = krbCryptoLength(krbContext, krbCrypto,
 333                            KRB5_CRYPTO_TYPE_HEADER, &headerLength);
 334     if (code != 0)
 335         return code;
 336
 337     dataLength += headerLength;
 338
 339     code = krb5_crypto_length(krbContext, krbCrypto,
 340                               KRB5_CRYPTO_TYPE_PADDING, &paddingLength);
 341     if (code != 0)
 342         return code;
 343
 344     if (paddingLength != 0 && (dataLength % paddingLength) != 0)
 345         *padLength = paddingLength - (dataLength % paddingLength);
 346     else
 347         *padLength = 0;
 348
 349     return 0;
 350 #else
 351     unsigned int pad;
 352
 353     code = krb5_c_padding_length(krbContext, KRB_KEY_TYPE(key), dataLength, &pad);
 354     if (code == 0)
 355         *padLength = (size_t)pad;
 356
 357     return code;
 358 #endif /* HAVE_HEIMDAL_VERSION */
 359 }
 360
 361 krb5_error_code
 362 krbBlockSize(krb5_context krbContext,
 363 #ifdef HAVE_HEIMDAL_VERSION
 364                  krb5_crypto krbCrypto,
 365 #else
 366                  krb5_keyblock *key,
 367 #endif
 368                  size_t *blockSize)
 369 {
 370 #ifdef HAVE_HEIMDAL_VERSION
 371     return krb5_crypto_getblocksize(krbContext, krbCrypto, blockSize);
 372 #else
 373     return krb5_c_block_size(krbContext, KRB_KEY_TYPE(key), blockSize);
 374 #endif
 375 }
 376
 377 krb5_error_code
 378 krbEnctypeToString(
 379 #ifdef HAVE_HEIMDAL_VERSION
 380                    krb5_context krbContext,
 381 #else
 382                    krb5_context krbContext GSSEAP_UNUSED,
 383 #endif
 384                    krb5_enctype enctype,
 385                    const char *prefix,
 386                    gss_buffer_t string)
 387 {
 388     krb5_error_code code;
 389 #ifdef HAVE_HEIMDAL_VERSION
 390     char *enctypeBuf = NULL;
 391 #else
 392     char enctypeBuf[128];
 393 #endif
 394     size_t prefixLength, enctypeLength;
 395
 396 #ifdef HAVE_HEIMDAL_VERSION
 397     code = krb5_enctype_to_string(krbContext, enctype, &enctypeBuf);
 398 #else
 399     code = krb5_enctype_to_name(enctype, 0, enctypeBuf, sizeof(enctypeBuf));
 400 #endif
 401     if (code != 0)
 402         return code;
 403
 404     prefixLength = (prefix != NULL) ? strlen(prefix) : 0;
 405     enctypeLength = strlen(enctypeBuf);
 406
 407     string->value = GSSEAP_MALLOC(prefixLength + enctypeLength + 1);
 408     if (string->value == NULL) {
 409 #ifdef HAVE_HEIMDAL_VERSION
 410         krb5_xfree(enctypeBuf);
 411 #endif
 412         return ENOMEM;
 413     }
 414
 415     if (prefixLength != 0)
 416         memcpy(string->value, prefix, prefixLength);
 417     memcpy((char *)string->value + prefixLength, enctypeBuf, enctypeLength);
 418
 419     string->length = prefixLength + enctypeLength;
 420     ((char *)string->value)[string->length] = '\0';
 421
 422 #ifdef HAVE_HEIMDAL_VERSION
 423     krb5_xfree(enctypeBuf);
 424 #endif
 425
 426     return 0;
 427 }
 428
 429 krb5_error_code
 430 krbMakeAuthDataKdcIssued(krb5_context context,
 431                          const krb5_keyblock *key,
 432                          krb5_const_principal issuer,
 433 #ifdef HAVE_HEIMDAL_VERSION
 434                          const AuthorizationData *authdata,
 435                          AuthorizationData *adKdcIssued
 436 #else
 437                          krb5_authdata *const *authdata,
 438                          krb5_authdata ***adKdcIssued
 439 #endif
 440                          )
 441 {
 442 #ifdef HAVE_HEIMDAL_VERSION
 443     krb5_error_code code;
 444     AD_KDCIssued kdcIssued;
 445     AuthorizationDataElement adDatum;
 446     unsigned char *buf;
 447     size_t buf_size, len;
 448     krb5_crypto crypto = NULL;
 449
 450     memset(&kdcIssued, 0, sizeof(kdcIssued));
 451     memset(adKdcIssued, 0, sizeof(*adKdcIssued));
 452
 453     kdcIssued.i_realm = issuer->realm != NULL ? (Realm *)&issuer->realm : NULL;
 454     kdcIssued.i_sname = (PrincipalName *)&issuer->name;
 455     kdcIssued.elements = *authdata;
 456
 457     ASN1_MALLOC_ENCODE(AuthorizationData, buf, buf_size, authdata, &len, code);
 458     if (code != 0)
 459         goto cleanup;
 460
 461     code = krb5_crypto_init(context, key, 0, &crypto);
 462     if (code != 0)
 463         goto cleanup;
 464
 465     code = krb5_create_checksum(context, crypto, KRB5_KU_AD_KDC_ISSUED,
 466                                 0, buf, buf_size, &kdcIssued.ad_checksum);
 467     if (code != 0)
 468         goto cleanup;
 469
 470     free(buf); /* match ASN1_MALLOC_ENCODE */
 471     buf = NULL;
 472
 473     ASN1_MALLOC_ENCODE(AD_KDCIssued, buf, buf_size, &kdcIssued, &len, code);
 474     if (code != 0)
 475         goto cleanup;
 476
 477     adDatum.ad_type = KRB5_AUTHDATA_KDC_ISSUED;
 478     adDatum.ad_data.length = buf_size;
 479     adDatum.ad_data.data = buf;
 480
 481     code = add_AuthorizationData(adKdcIssued, &adDatum);
 482     if (code != 0)
 483         goto cleanup;
 484
 485 cleanup:
 486     if (buf != NULL)
 487         free(buf); /* match ASN1_MALLOC_ENCODE */
 488     if (crypto != NULL)
 489         krb5_crypto_destroy(context, crypto);
 490     free_Checksum(&kdcIssued.ad_checksum);
 491
 492     return code;
 493 #else
 494     return krb5_make_authdata_kdc_issued(context, key, issuer, authdata,
 495                                          adKdcIssued);
 496 #endif /* HAVE_HEIMDAL_VERSION */
 497 }
 498
 499 krb5_error_code
 500 krbMakeCred(krb5_context krbContext,
 501             krb5_auth_context authContext,
 502             krb5_creds *creds,
 503             krb5_data *data)
 504 {
 505     krb5_error_code code;
 506 #ifdef HAVE_HEIMDAL_VERSION
 507     KRB_CRED krbCred;
 508     KrbCredInfo krbCredInfo;
 509     EncKrbCredPart encKrbCredPart;
 510     krb5_keyblock *key;
 511     krb5_crypto krbCrypto = NULL;
 512     krb5_data encKrbCredPartData;
 513     krb5_replay_data rdata;
 514     size_t len;
 515 #else
 516     krb5_data *d = NULL;
 517 #endif
 518
 519     memset(data, 0, sizeof(*data));
 520 #ifdef HAVE_HEIMDAL_VERSION
 521     memset(&krbCred,        0, sizeof(krbCred));
 522     memset(&krbCredInfo,    0, sizeof(krbCredInfo));
 523     memset(&encKrbCredPart, 0, sizeof(encKrbCredPart));
 524     memset(&rdata,          0, sizeof(rdata));
 525
 526     if (authContext->local_subkey)
 527         key = authContext->local_subkey;
 528     else if (authContext->remote_subkey)
 529         key = authContext->remote_subkey;
 530     else
 531         key = authContext->keyblock;
 532
 533     krbCred.pvno = 5;
 534     krbCred.msg_type = krb_cred;
 535     krbCred.tickets.val = (Ticket *)GSSEAP_CALLOC(1, sizeof(Ticket));
 536     if (krbCred.tickets.val == NULL) {
 537         code = ENOMEM;
 538         goto cleanup;
 539     }
 540     krbCred.tickets.len = 1;
 541
 542     code = decode_Ticket(creds->ticket.data,
 543                          creds->ticket.length,
 544                          krbCred.tickets.val, &len);
 545     if (code != 0)
 546         goto cleanup;
 547
 548     krbCredInfo.key         = creds->session;
 549     krbCredInfo.prealm      = &creds->client->realm;
 550     krbCredInfo.pname       = &creds->client->name;
 551     krbCredInfo.flags       = &creds->flags.b;
 552     krbCredInfo.authtime    = &creds->times.authtime;
 553     krbCredInfo.starttime   = &creds->times.starttime;
 554     krbCredInfo.endtime     = &creds->times.endtime;
 555     krbCredInfo.renew_till  = &creds->times.renew_till;
 556     krbCredInfo.srealm      = &creds->server->realm;
 557     krbCredInfo.sname       = &creds->server->name;
 558     krbCredInfo.caddr       = creds->addresses.len ? &creds->addresses : NULL;
 559
 560     encKrbCredPart.ticket_info.len = 1;
 561     encKrbCredPart.ticket_info.val = &krbCredInfo;
 562     if (authContext->flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE) {
 563         rdata.seq                  = authContext->local_seqnumber;
 564         encKrbCredPart.nonce       = (int32_t *)&rdata.seq;
 565     } else {
 566         encKrbCredPart.nonce       = NULL;
 567     }
 568     if (authContext->flags & KRB5_AUTH_CONTEXT_DO_TIME) {
 569         krb5_us_timeofday(krbContext, &rdata.timestamp, &rdata.usec);
 570         encKrbCredPart.timestamp   = &rdata.timestamp;
 571         encKrbCredPart.usec        = &rdata.usec;
 572     } else {
 573         encKrbCredPart.timestamp   = NULL;
 574         encKrbCredPart.usec        = NULL;
 575     }
 576     encKrbCredPart.s_address       = authContext->local_address;
 577     encKrbCredPart.r_address       = authContext->remote_address;
 578
 579     ASN1_MALLOC_ENCODE(EncKrbCredPart, encKrbCredPartData.data,
 580                        encKrbCredPartData.length, &encKrbCredPart,
 581                        &len, code);
 582     if (code != 0)
 583         goto cleanup;
 584
 585     code = krb5_crypto_init(krbContext, key, 0, &krbCrypto);
 586     if (code != 0)
 587         goto cleanup;
 588
 589     code = krb5_encrypt_EncryptedData(krbContext,
 590                                       krbCrypto,
 591                                       KRB5_KU_KRB_CRED,
 592                                       encKrbCredPartData.data,
 593                                       encKrbCredPartData.length,
 594                                       0,
 595                                       &krbCred.enc_part);
 596     if (code != 0)
 597         goto cleanup;
 598
 599     ASN1_MALLOC_ENCODE(KRB_CRED, data->data, data->length,
 600                        &krbCred, &len, code);
 601     if (code != 0)
 602         goto cleanup;
 603
 604     if (authContext->flags & KRB5_AUTH_CONTEXT_DO_SEQUENCE)
 605         authContext->local_seqnumber++;
 606
 607 cleanup:
 608     if (krbCrypto != NULL)
 609         krb5_crypto_destroy(krbContext, krbCrypto);
 610     free_KRB_CRED(&krbCred);
 611     krb5_data_free(&encKrbCredPartData);
 612
 613     return code;
 614 #else
 615     code = krb5_mk_1cred(krbContext, authContext, creds, &d, NULL);
 616     if (code == 0) {
 617         *data = *d;
 618         GSSEAP_FREE(d);
 619     }
 620
 621     return code;
 622 #endif /* HAVE_HEIMDAL_VERSION */
 623 }