kcm/acquire.c

   1 /*
   2  * Copyright (c) 2005, PADL Software Pty Ltd.
   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 PADL Software 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 PADL SOFTWARE AND CONTRIBUTORS ``AS IS'' AND
  21  * 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 PADL SOFTWARE 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 #include "kcm_locl.h"
  34
  35 RCSID("$Id$");
  36
  37 static krb5_error_code
  38 change_pw_and_update_keytab(krb5_context context, kcm_ccache ccache);
  39
  40 /*
  41  * Get a new ticket using a keytab/cached key and swap it into
  42  * an existing redentials cache
  43  */
  44
  45 krb5_error_code
  46 kcm_ccache_acquire(krb5_context context,
  47                    kcm_ccache ccache,
  48                    krb5_creds **credp)
  49 {
  50     krb5_error_code ret = 0;
  51     krb5_creds cred;
  52     krb5_const_realm realm;
  53     krb5_get_init_creds_opt *opt = NULL;
  54     krb5_ccache_data ccdata;
  55     char *in_tkt_service = NULL;
  56     int done = 0;
  57
  58     memset(&cred, 0, sizeof(cred));
  59
  60     KCM_ASSERT_VALID(ccache);
  61
  62     /* We need a cached key or keytab to acquire credentials */
  63     if (ccache->flags & KCM_FLAGS_USE_CACHED_KEY) {
  64         if (ccache->key.keyblock.keyvalue.length == 0)
  65             krb5_abortx(context,
  66                         "kcm_ccache_acquire: KCM_FLAGS_USE_CACHED_KEY without key");
  67     } else if (ccache->flags & KCM_FLAGS_USE_KEYTAB) {
  68         if (ccache->key.keytab == NULL)
  69             krb5_abortx(context,
  70                         "kcm_ccache_acquire: KCM_FLAGS_USE_KEYTAB without keytab");
  71     } else {
  72         kcm_log(0, "Cannot acquire initial credentials for cache %s without key",
  73                 ccache->name);
  74         return KRB5_FCC_INTERNAL;
  75     }
  76
  77     HEIMDAL_MUTEX_lock(&ccache->mutex);
  78
  79     /* Fake up an internal ccache */
  80     kcm_internal_ccache(context, ccache, &ccdata);
  81
  82     /* Now, actually acquire the creds */
  83     if (ccache->server != NULL) {
  84         ret = krb5_unparse_name(context, ccache->server, &in_tkt_service);
  85         if (ret) {
  86             kcm_log(0, "Failed to unparse service principal name for cache %s: %s",
  87                     ccache->name, krb5_get_err_text(context, ret));
  88             return ret;
  89         }
  90     }
  91
  92     realm = krb5_principal_get_realm(context, ccache->client);
  93
  94     krb5_get_init_creds_opt_alloc(context, &opt);
  95     krb5_get_init_creds_opt_set_default_flags(context, "kcm", realm, opt);
  96     if (ccache->tkt_life != 0)
  97         krb5_get_init_creds_opt_set_tkt_life(opt, ccache->tkt_life);
  98     if (ccache->renew_life != 0)
  99         krb5_get_init_creds_opt_set_renew_life(opt, ccache->renew_life);
 100
 101     if (ccache->flags & KCM_FLAGS_USE_CACHED_KEY) {
 102         ret = krb5_get_init_creds_keyblock(context,
 103                                            &cred,
 104                                            ccache->client,
 105                                            &ccache->key.keyblock,
 106                                            0,
 107                                            in_tkt_service,
 108                                            opt);
 109     } else {
 110         /* loosely based on lib/krb5/init_creds_pw.c */
 111         while (!done) {
 112             ret = krb5_get_init_creds_keytab(context,
 113                                              &cred,
 114                                              ccache->client,
 115                                              ccache->key.keytab,
 116                                              0,
 117                                              in_tkt_service,
 118                                              opt);
 119             switch (ret) {
 120             case KRB5KDC_ERR_KEY_EXPIRED:
 121                 if (in_tkt_service != NULL &&
 122                     strcmp(in_tkt_service, "kadmin/changepw") == 0) {
 123                     goto out;
 124                 }
 125
 126                 ret = change_pw_and_update_keytab(context, ccache);
 127                 if (ret)
 128                     goto out;
 129                 break;
 130             case 0:
 131             default:
 132                 done = 1;
 133                 break;
 134             }
 135         }
 136     }
 137
 138     if (ret) {
 139         kcm_log(0, "Failed to acquire credentials for cache %s: %s",
 140                 ccache->name, krb5_get_err_text(context, ret));
 141         if (in_tkt_service != NULL)
 142             free(in_tkt_service);
 143         goto out;
 144     }
 145
 146     if (in_tkt_service != NULL)
 147         free(in_tkt_service);
 148
 149     /* Swap them in */
 150     kcm_ccache_remove_creds_internal(context, ccache);
 151
 152     ret = kcm_ccache_store_cred_internal(context, ccache, &cred, 0, credp);
 153     if (ret) {
 154         kcm_log(0, "Failed to store credentials for cache %s: %s",
 155                 ccache->name, krb5_get_err_text(context, ret));
 156         krb5_free_cred_contents(context, &cred);
 157         goto out;
 158     }
 159
 160 out:
 161     if (opt)
 162         krb5_get_init_creds_opt_free(context, opt);
 163
 164     HEIMDAL_MUTEX_unlock(&ccache->mutex);
 165
 166     return ret;
 167 }
 168
 169 static krb5_error_code
 170 change_pw(krb5_context context,
 171           kcm_ccache ccache,
 172           char *cpn,
 173           char *newpw)
 174 {
 175     krb5_error_code ret;
 176     krb5_creds cpw_cred;
 177     int result_code;
 178     krb5_data result_code_string;
 179     krb5_data result_string;
 180     krb5_get_init_creds_opt *options;
 181
 182     memset(&cpw_cred, 0, sizeof(cpw_cred));
 183
 184     ret = krb5_get_init_creds_opt_alloc(context, &options);
 185     if (ret)
 186         return ret;
 187     krb5_get_init_creds_opt_set_tkt_life(options, 60);
 188     krb5_get_init_creds_opt_set_forwardable(options, FALSE);
 189     krb5_get_init_creds_opt_set_proxiable(options, FALSE);
 190
 191     krb5_data_zero(&result_code_string);
 192     krb5_data_zero(&result_string);
 193
 194     ret = krb5_get_init_creds_keytab(context,
 195                                      &cpw_cred,
 196                                      ccache->client,
 197                                      ccache->key.keytab,
 198                                      0,
 199                                      "kadmin/changepw",
 200                                      options);
 201     krb5_get_init_creds_opt_free(context, options);
 202     if (ret) {
 203         kcm_log(0, "Failed to acquire password change credentials "
 204                 "for principal %s: %s",
 205                 cpn, krb5_get_err_text(context, ret));
 206         goto out;
 207     }
 208
 209     ret = krb5_set_password(context,
 210                             &cpw_cred,
 211                             newpw,
 212                             ccache->client,
 213                             &result_code,
 214                             &result_code_string,
 215                             &result_string);
 216     if (ret) {
 217         kcm_log(0, "Failed to change password for principal %s: %s",
 218                 cpn, krb5_get_err_text(context, ret));
 219         goto out;
 220     }
 221
 222     if (result_code) {
 223         kcm_log(0, "Failed to change password for principal %s: %.*s",
 224                 cpn,
 225                 (int)result_string.length,
 226                 result_string.length > 0 ? (char *)result_string.data : "");
 227         goto out;
 228     }
 229
 230 out:
 231     krb5_data_free(&result_string);
 232     krb5_data_free(&result_code_string);
 233     krb5_free_cred_contents(context, &cpw_cred);
 234
 235     return ret;
 236 }
 237
 238 struct kcm_keyseed_data {
 239     krb5_salt salt;
 240     const char *password;
 241 };
 242
 243 static krb5_error_code
 244 kcm_password_key_proc(krb5_context context,
 245                       krb5_enctype etype,
 246                       krb5_salt salt,
 247                       krb5_const_pointer keyseed,
 248                       krb5_keyblock **key)
 249 {
 250     krb5_error_code ret;
 251     struct kcm_keyseed_data *s = (struct kcm_keyseed_data *)keyseed;
 252
 253     /* we may be called multiple times */
 254     krb5_free_salt(context, s->salt);
 255     krb5_data_zero(&s->salt.saltvalue);
 256
 257     /* stash the salt */
 258     s->salt.salttype = salt.salttype;
 259
 260     ret = krb5_data_copy(&s->salt.saltvalue,
 261                          salt.saltvalue.data,
 262                          salt.saltvalue.length);
 263     if (ret)
 264         return ret;
 265
 266     *key = (krb5_keyblock *)malloc(sizeof(**key));
 267     if (*key == NULL) {
 268         return ENOMEM;
 269     }
 270
 271     ret = krb5_string_to_key_salt(context, etype, s->password,
 272                                   s->salt, *key);
 273     if (ret) {
 274         free(*key);
 275         *key = NULL;
 276     }
 277
 278     return ret;
 279 }
 280
 281 static krb5_error_code
 282 get_salt_and_kvno(krb5_context context,
 283                   kcm_ccache ccache,
 284                   krb5_enctype *etypes,
 285                   char *cpn,
 286                   char *newpw,
 287                   krb5_salt *salt,
 288                   unsigned *kvno)
 289 {
 290     krb5_error_code ret;
 291     krb5_creds creds;
 292     krb5_ccache_data ccdata;
 293     krb5_flags options = 0;
 294     krb5_kdc_rep reply;
 295     struct kcm_keyseed_data s;
 296
 297     memset(&creds, 0, sizeof(creds));
 298     memset(&reply, 0, sizeof(reply));
 299
 300     s.password = NULL;
 301     s.salt.salttype = (int)ETYPE_NULL;
 302     krb5_data_zero(&s.salt.saltvalue);
 303
 304     *kvno = 0;
 305     kcm_internal_ccache(context, ccache, &ccdata);
 306     s.password = newpw;
 307
 308     /* Do an AS-REQ to determine salt and key version number */
 309     ret = krb5_copy_principal(context, ccache->client, &creds.client);
 310     if (ret)
 311         return ret;
 312
 313     /* Yes, get a ticket to ourselves */
 314     ret = krb5_copy_principal(context, ccache->client, &creds.server);
 315     if (ret) {
 316         krb5_free_principal(context, creds.client);
 317         return ret;
 318     }
 319
 320     ret = krb5_get_in_tkt(context,
 321                           options,
 322                           NULL,
 323                           etypes,
 324                           NULL,
 325                           kcm_password_key_proc,
 326                           &s,
 327                           NULL,
 328                           NULL,
 329                           &creds,
 330                           &ccdata,
 331                           &reply);
 332     if (ret) {
 333         kcm_log(0, "Failed to get self ticket for principal %s: %s",
 334                 cpn, krb5_get_err_text(context, ret));
 335         krb5_free_salt(context, s.salt);
 336     } else {
 337         *salt = s.salt; /* retrieve stashed salt */
 338         if (reply.kdc_rep.enc_part.kvno != NULL)
 339             *kvno = *(reply.kdc_rep.enc_part.kvno);
 340     }
 341     /* ccache may have been modified but it will get trashed anyway */
 342
 343     krb5_free_cred_contents(context, &creds);
 344     krb5_free_kdc_rep(context, &reply);
 345
 346     return ret;
 347 }
 348
 349 static krb5_error_code
 350 update_keytab_entry(krb5_context context,
 351                     kcm_ccache ccache,
 352                     krb5_enctype etype,
 353                     char *cpn,
 354                     char *spn,
 355                     char *newpw,
 356                     krb5_salt salt,
 357                     unsigned kvno)
 358 {
 359     krb5_error_code ret;
 360     krb5_keytab_entry entry;
 361     krb5_data pw;
 362
 363     memset(&entry, 0, sizeof(entry));
 364
 365     pw.data = (char *)newpw;
 366     pw.length = strlen(newpw);
 367
 368     ret = krb5_string_to_key_data_salt(context, etype, pw,
 369                                        salt, &entry.keyblock);
 370     if (ret) {
 371         kcm_log(0, "String to key conversion failed for principal %s "
 372                 "and etype %d: %s",
 373                 cpn, etype, krb5_get_err_text(context, ret));
 374         return ret;
 375     }
 376
 377     if (spn == NULL) {
 378         ret = krb5_copy_principal(context, ccache->client,
 379                                   &entry.principal);
 380         if (ret) {
 381             kcm_log(0, "Failed to copy principal name %s: %s",
 382                     cpn, krb5_get_err_text(context, ret));
 383             return ret;
 384         }
 385     } else {
 386         ret = krb5_parse_name(context, spn, &entry.principal);
 387         if (ret) {
 388             kcm_log(0, "Failed to parse SPN alias %s: %s",
 389                     spn, krb5_get_err_text(context, ret));
 390             return ret;
 391         }
 392     }
 393
 394     entry.vno = kvno;
 395     entry.timestamp = time(NULL);
 396
 397     ret = krb5_kt_add_entry(context, ccache->key.keytab, &entry);
 398     if (ret) {
 399         kcm_log(0, "Failed to update keytab for principal %s "
 400                 "and etype %d: %s",
 401                 cpn, etype, krb5_get_err_text(context, ret));
 402     }
 403
 404     krb5_kt_free_entry(context, &entry);
 405
 406     return ret;
 407 }
 408
 409 static krb5_error_code
 410 update_keytab_entries(krb5_context context,
 411                       kcm_ccache ccache,
 412                       krb5_enctype *etypes,
 413                       char *cpn,
 414                       char *spn,
 415                       char *newpw,
 416                       krb5_salt salt,
 417                       unsigned kvno)
 418 {
 419     krb5_error_code ret = 0;
 420     int i;
 421
 422     for (i = 0; etypes[i] != ETYPE_NULL; i++) {
 423         ret = update_keytab_entry(context, ccache, etypes[i],
 424                                   cpn, spn, newpw, salt, kvno);
 425         if (ret)
 426             break;
 427     }
 428
 429     return ret;
 430 }
 431
 432 static void
 433 generate_random_pw(krb5_context context,
 434                    char *buf,
 435                    size_t bufsiz)
 436 {
 437     unsigned char x[512], *p;
 438     size_t i;
 439
 440     memset(x, 0, sizeof(x));
 441     krb5_generate_random_block(x, sizeof(x));
 442     p = x;
 443
 444     for (i = 0; i < bufsiz; i++) {
 445         while (isprint(*p) == 0)
 446             p++;
 447
 448         if (p - x >= sizeof(x)) {
 449             krb5_generate_random_block(x, sizeof(x));
 450             p = x;
 451         }
 452         buf[i] = (char)*p++;
 453     }
 454     buf[bufsiz - 1] = '\0';
 455     memset(x, 0, sizeof(x));
 456 }
 457
 458 static krb5_error_code
 459 change_pw_and_update_keytab(krb5_context context,
 460                             kcm_ccache ccache)
 461 {
 462     char newpw[121];
 463     krb5_error_code ret;
 464     unsigned kvno;
 465     krb5_salt salt;
 466     krb5_enctype *etypes = NULL;
 467     int i;
 468     char *cpn = NULL;
 469     char **spns = NULL;
 470
 471     krb5_data_zero(&salt.saltvalue);
 472
 473     ret = krb5_unparse_name(context, ccache->client, &cpn);
 474     if (ret) {
 475         kcm_log(0, "Failed to unparse name: %s",
 476                 krb5_get_err_text(context, ret));
 477         goto out;
 478     }
 479
 480     ret = krb5_get_default_in_tkt_etypes(context, &etypes);
 481     if (ret) {
 482         kcm_log(0, "Failed to determine default encryption types: %s",
 483                 krb5_get_err_text(context, ret));
 484         goto out;
 485     }
 486
 487     /* Generate a random password (there is no set keys protocol) */
 488     generate_random_pw(context, newpw, sizeof(newpw));
 489
 490     /* Change it */
 491     ret = change_pw(context, ccache, cpn, newpw);
 492     if (ret)
 493         goto out;
 494
 495     /* Do an AS-REQ to determine salt and key version number */
 496     ret = get_salt_and_kvno(context, ccache, etypes, cpn, newpw,
 497                             &salt, &kvno);
 498     if (ret) {
 499         kcm_log(0, "Failed to determine salting principal for principal %s: %s",
 500                 cpn, krb5_get_err_text(context, ret));
 501         goto out;
 502     }
 503
 504     /* Add canonical name */
 505     ret = update_keytab_entries(context, ccache, etypes, cpn,
 506                                 NULL, newpw, salt, kvno);
 507     if (ret)
 508         goto out;
 509
 510     /* Add SPN aliases, if any */
 511     spns = krb5_config_get_strings(context, NULL, "kcm",
 512                                    "system_ccache", "spn_aliases", NULL);
 513     if (spns != NULL) {
 514         for (i = 0; spns[i] != NULL; i++) {
 515             ret = update_keytab_entries(context, ccache, etypes, cpn,
 516                                         spns[i], newpw, salt, kvno);
 517             if (ret)
 518                 goto out;
 519         }
 520     }
 521
 522     kcm_log(0, "Changed expired password for principal %s in cache %s",
 523             cpn, ccache->name);
 524
 525 out:
 526     if (cpn != NULL)
 527         free(cpn);
 528     if (spns != NULL)
 529         krb5_config_free_strings(spns);
 530     if (etypes != NULL)
 531         free(etypes);
 532     krb5_free_salt(context, salt);
 533     memset(newpw, 0, sizeof(newpw));
 534
 535     return ret;
 536 }
 537