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;
  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_init(&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     HEIMDAL_MUTEX_unlock(&ccache->mutex);
 162
 163     return ret;
 164 }
 165
 166 static krb5_error_code
 167 change_pw(krb5_context context,
 168           kcm_ccache ccache,
 169           char *cpn,
 170           char *newpw)
 171 {
 172     krb5_error_code ret;
 173     krb5_creds cpw_cred;
 174     int result_code;
 175     krb5_data result_code_string;
 176     krb5_data result_string;
 177     krb5_get_init_creds_opt options;
 178
 179     memset(&cpw_cred, 0, sizeof(cpw_cred));
 180
 181     krb5_get_init_creds_opt_init(&options);
 182     krb5_get_init_creds_opt_set_tkt_life(&options, 60);
 183     krb5_get_init_creds_opt_set_forwardable(&options, FALSE);
 184     krb5_get_init_creds_opt_set_proxiable(&options, FALSE);
 185
 186     krb5_data_zero(&result_code_string);
 187     krb5_data_zero(&result_string);
 188
 189     ret = krb5_get_init_creds_keytab(context,
 190                                      &cpw_cred,
 191                                      ccache->client,
 192                                      ccache->key.keytab,
 193                                      0,
 194                                      "kadmin/changepw",
 195                                      &options);
 196     if (ret) {
 197         kcm_log(0, "Failed to acquire password change credentials "
 198                 "for principal %s: %s",
 199                 cpn, krb5_get_err_text(context, ret));
 200         goto out;
 201     }
 202
 203     ret = krb5_set_password(context,
 204                             &cpw_cred,
 205                             newpw,
 206                             ccache->client,
 207                             &result_code,
 208                             &result_code_string,
 209                             &result_string);
 210     if (ret) {
 211         kcm_log(0, "Failed to change password for principal %s: %s",
 212                 cpn, krb5_get_err_text(context, ret));
 213         goto out;
 214     }
 215
 216     if (result_code) {
 217         kcm_log(0, "Failed to change password for principal %s: %.*s",
 218                 cpn,
 219                 (int)result_string.length,
 220                 result_string.length > 0 ? (char *)result_string.data : "");
 221         goto out;
 222     }
 223
 224 out:
 225     krb5_data_free(&result_string);
 226     krb5_data_free(&result_code_string);
 227     krb5_free_cred_contents(context, &cpw_cred);
 228
 229     return ret;
 230 }
 231
 232 struct kcm_keyseed_data {
 233     krb5_salt salt;
 234     const char *password;
 235 };
 236
 237 static krb5_error_code
 238 kcm_password_key_proc(krb5_context context,
 239                       krb5_enctype etype,
 240                       krb5_salt salt,
 241                       krb5_const_pointer keyseed,
 242                       krb5_keyblock **key)
 243 {
 244     krb5_error_code ret;
 245     struct kcm_keyseed_data *s = (struct kcm_keyseed_data *)keyseed;
 246
 247     /* we may be called multiple times */
 248     krb5_free_salt(context, s->salt);
 249     krb5_data_zero(&s->salt.saltvalue);
 250
 251     /* stash the salt */
 252     s->salt.salttype = salt.salttype;
 253
 254     ret = krb5_data_copy(&s->salt.saltvalue,
 255                          salt.saltvalue.data,
 256                          salt.saltvalue.length);
 257     if (ret)
 258         return ret;
 259
 260     *key = (krb5_keyblock *)malloc(sizeof(**key));
 261     if (*key == NULL) {
 262         return ENOMEM;
 263     }
 264
 265     ret = krb5_string_to_key_salt(context, etype, s->password,
 266                                   s->salt, *key);
 267     if (ret) {
 268         free(*key);
 269         *key = NULL;
 270     }
 271
 272     return ret;
 273 }
 274
 275 static krb5_error_code
 276 get_salt_and_kvno(krb5_context context,
 277                   kcm_ccache ccache,
 278                   krb5_enctype *etypes,
 279                   char *cpn,
 280                   char *newpw,
 281                   krb5_salt *salt,
 282                   unsigned *kvno)
 283 {
 284     krb5_error_code ret;
 285     krb5_creds creds;
 286     krb5_ccache_data ccdata;
 287     krb5_flags options = 0;
 288     krb5_kdc_rep reply;
 289     struct kcm_keyseed_data s;
 290
 291     memset(&creds, 0, sizeof(creds));
 292     memset(&reply, 0, sizeof(reply));
 293
 294     s.password = NULL;
 295     s.salt.salttype = (int)ETYPE_NULL;
 296     krb5_data_zero(&s.salt.saltvalue);
 297
 298     *kvno = 0;
 299     kcm_internal_ccache(context, ccache, &ccdata);
 300     s.password = newpw;
 301
 302     /* Do an AS-REQ to determine salt and key version number */
 303     ret = krb5_copy_principal(context, ccache->client, &creds.client);
 304     if (ret)
 305         return ret;
 306
 307     /* Yes, get a ticket to ourselves */
 308     ret = krb5_copy_principal(context, ccache->client, &creds.server);
 309     if (ret) {
 310         krb5_free_principal(context, creds.client);
 311         return ret;
 312     }
 313
 314     ret = krb5_get_in_tkt(context,
 315                           options,
 316                           NULL,
 317                           etypes,
 318                           NULL,
 319                           kcm_password_key_proc,
 320                           &s,
 321                           NULL,
 322                           NULL,
 323                           &creds,
 324                           &ccdata,
 325                           &reply);
 326     if (ret) {
 327         kcm_log(0, "Failed to get self ticket for principal %s: %s",
 328                 cpn, krb5_get_err_text(context, ret));
 329         krb5_free_salt(context, s.salt);
 330     } else {
 331         *salt = s.salt; /* retrieve stashed salt */
 332         if (reply.kdc_rep.enc_part.kvno != NULL)
 333             *kvno = *(reply.kdc_rep.enc_part.kvno);
 334     }
 335     /* ccache may have been modified but it will get trashed anyway */
 336
 337     krb5_free_cred_contents(context, &creds);
 338     krb5_free_kdc_rep(context, &reply);
 339
 340     return ret;
 341 }
 342
 343 static krb5_error_code
 344 update_keytab_entry(krb5_context context,
 345                     kcm_ccache ccache,
 346                     krb5_enctype etype,
 347                     char *cpn,
 348                     char *spn,
 349                     char *newpw,
 350                     krb5_salt salt,
 351                     unsigned kvno)
 352 {
 353     krb5_error_code ret;
 354     krb5_keytab_entry entry;
 355     krb5_data pw;
 356
 357     memset(&entry, 0, sizeof(entry));
 358
 359     pw.data = (char *)newpw;
 360     pw.length = strlen(newpw);
 361
 362     ret = krb5_string_to_key_data_salt(context, etype, pw,
 363                                        salt, &entry.keyblock);
 364     if (ret) {
 365         kcm_log(0, "String to key conversion failed for principal %s "
 366                 "and etype %d: %s",
 367                 cpn, etype, krb5_get_err_text(context, ret));
 368         return ret;
 369     }
 370
 371     if (spn == NULL) {
 372         ret = krb5_copy_principal(context, ccache->client,
 373                                   &entry.principal);
 374         if (ret) {
 375             kcm_log(0, "Failed to copy principal name %s: %s",
 376                     cpn, krb5_get_err_text(context, ret));
 377             return ret;
 378         }
 379     } else {
 380         ret = krb5_parse_name(context, spn, &entry.principal);
 381         if (ret) {
 382             kcm_log(0, "Failed to parse SPN alias %s: %s",
 383                     spn, krb5_get_err_text(context, ret));
 384             return ret;
 385         }
 386     }
 387
 388     entry.vno = kvno;
 389     entry.timestamp = time(NULL);
 390
 391     ret = krb5_kt_add_entry(context, ccache->key.keytab, &entry);
 392     if (ret) {
 393         kcm_log(0, "Failed to update keytab for principal %s "
 394                 "and etype %d: %s",
 395                 cpn, etype, krb5_get_err_text(context, ret));
 396     }
 397
 398     krb5_kt_free_entry(context, &entry);
 399
 400     return ret;
 401 }
 402
 403 static krb5_error_code
 404 update_keytab_entries(krb5_context context,
 405                       kcm_ccache ccache,
 406                       krb5_enctype *etypes,
 407                       char *cpn,
 408                       char *spn,
 409                       char *newpw,
 410                       krb5_salt salt,
 411                       unsigned kvno)
 412 {
 413     krb5_error_code ret = 0;
 414     int i;
 415
 416     for (i = 0; etypes[i] != ETYPE_NULL; i++) {
 417         ret = update_keytab_entry(context, ccache, etypes[i],
 418                                   cpn, spn, newpw, salt, kvno);
 419         if (ret)
 420             break;
 421     }
 422
 423     return ret;
 424 }
 425
 426 static void
 427 generate_random_pw(krb5_context context,
 428                    char *buf,
 429                    size_t bufsiz)
 430 {
 431     unsigned char x[512], *p;
 432     size_t i;
 433
 434     memset(x, 0, sizeof(x));
 435     krb5_generate_random_block(x, sizeof(x));
 436     p = x;
 437
 438     for (i = 0; i < bufsiz; i++) {
 439         while (isprint(*p) == 0)
 440             p++;
 441
 442         if (p - x >= sizeof(x)) {
 443             krb5_generate_random_block(x, sizeof(x));
 444             p = x;
 445         }
 446         buf[i] = (char)*p++;
 447     }
 448     buf[bufsiz - 1] = '\0';
 449     memset(x, 0, sizeof(x));
 450 }
 451
 452 static krb5_error_code
 453 change_pw_and_update_keytab(krb5_context context,
 454                             kcm_ccache ccache)
 455 {
 456     char newpw[121];
 457     krb5_error_code ret;
 458     unsigned kvno;
 459     krb5_salt salt;
 460     krb5_enctype *etypes = NULL;
 461     int i;
 462     char *cpn = NULL;
 463     char **spns = NULL;
 464
 465     krb5_data_zero(&salt.saltvalue);
 466
 467     ret = krb5_unparse_name(context, ccache->client, &cpn);
 468     if (ret) {
 469         kcm_log(0, "Failed to unparse name: %s",
 470                 krb5_get_err_text(context, ret));
 471         goto out;
 472     }
 473
 474     ret = krb5_get_default_in_tkt_etypes(context, &etypes);
 475     if (ret) {
 476         kcm_log(0, "Failed to determine default encryption types: %s",
 477                 krb5_get_err_text(context, ret));
 478         goto out;
 479     }
 480
 481     /* Generate a random password (there is no set keys protocol) */
 482     generate_random_pw(context, newpw, sizeof(newpw));
 483
 484     /* Change it */
 485     ret = change_pw(context, ccache, cpn, newpw);
 486     if (ret)
 487         goto out;
 488
 489     /* Do an AS-REQ to determine salt and key version number */
 490     ret = get_salt_and_kvno(context, ccache, etypes, cpn, newpw,
 491                             &salt, &kvno);
 492     if (ret) {
 493         kcm_log(0, "Failed to determine salting principal for principal %s: %s",
 494                 cpn, krb5_get_err_text(context, ret));
 495         goto out;
 496     }
 497
 498     /* Add canonical name */
 499     ret = update_keytab_entries(context, ccache, etypes, cpn,
 500                                 NULL, newpw, salt, kvno);
 501     if (ret)
 502         goto out;
 503
 504     /* Add SPN aliases, if any */
 505     spns = krb5_config_get_strings(context, NULL, "kcm",
 506                                    "system_ccache", "spn_aliases", NULL);
 507     if (spns != NULL) {
 508         for (i = 0; spns[i] != NULL; i++) {
 509             ret = update_keytab_entries(context, ccache, etypes, cpn,
 510                                         spns[i], newpw, salt, kvno);
 511             if (ret)
 512                 goto out;
 513         }
 514     }
 515
 516     kcm_log(0, "Changed expired password for principal %s in cache %s",
 517             cpn, ccache->name);
 518
 519 out:
 520     if (cpn != NULL)
 521         free(cpn);
 522     if (spns != NULL)
 523         krb5_config_free_strings(spns);
 524     if (etypes != NULL)
 525         free(etypes);
 526     krb5_free_salt(context, salt);
 527     memset(newpw, 0, sizeof(newpw));
 528
 529     return ret;
 530 }
 531