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_creds_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_change_password(context,
 204                                &cpw_cred,
 205                                newpw,
 206                                &result_code,
 207                                &result_code_string,
 208                                &result_string);
 209     if (ret) {
 210         kcm_log(0, "Failed to change password for principal %s: %s",
 211                 cpn, krb5_get_err_text(context, ret));
 212         goto out;
 213     }
 214
 215     if (result_code) {
 216         kcm_log(0, "Failed to change password for principal %s: %.*s",
 217                 cpn,
 218                 (int)result_string.length,
 219                 result_string.length > 0 ? (char *)result_string.data : "");
 220         goto out;
 221     }
 222
 223 out:
 224     krb5_data_free(&result_string);
 225     krb5_data_free(&result_code_string);
 226     krb5_free_cred_contents(context, &cpw_cred);
 227
 228     return ret;
 229 }
 230
 231 struct kcm_keyseed_data {
 232     krb5_salt salt;
 233     const char *password;
 234 };
 235
 236 static krb5_error_code
 237 kcm_password_key_proc(krb5_context context,
 238                       krb5_enctype etype,
 239                       krb5_salt salt,
 240                       krb5_const_pointer keyseed,
 241                       krb5_keyblock **key)
 242 {
 243     krb5_error_code ret;
 244     struct kcm_keyseed_data *s = (struct kcm_keyseed_data *)keyseed;
 245
 246     /* we may be called multiple times */
 247     krb5_free_salt(context, s->salt);
 248     krb5_data_zero(&s->salt.saltvalue);
 249
 250     /* stash the salt */
 251     s->salt.salttype = salt.salttype;
 252
 253     ret = krb5_data_copy(&s->salt.saltvalue,
 254                          salt.saltvalue.data,
 255                          salt.saltvalue.length);
 256     if (ret)
 257         return ret;
 258
 259     *key = (krb5_keyblock *)malloc(sizeof(**key));
 260     if (*key == NULL) {
 261         return ENOMEM;
 262     }
 263
 264     ret = krb5_string_to_key_salt(context, etype, s->password,
 265                                   s->salt, *key);
 266     if (ret) {
 267         free(*key);
 268         *key = NULL;
 269     }
 270
 271     return ret;
 272 }
 273
 274 static krb5_error_code
 275 get_salt_and_kvno(krb5_context context,
 276                   kcm_ccache ccache,
 277                   krb5_enctype *etypes,
 278                   char *cpn,
 279                   char *newpw,
 280                   krb5_salt *salt,
 281                   unsigned *kvno)
 282 {
 283     krb5_error_code ret;
 284     krb5_creds creds;
 285     krb5_ccache_data ccdata;
 286     krb5_flags options = 0;
 287     krb5_kdc_rep reply;
 288     struct kcm_keyseed_data s;
 289
 290     memset(&creds, 0, sizeof(creds));
 291     memset(&reply, 0, sizeof(reply));
 292
 293     s.password = NULL;
 294     s.salt.salttype = ETYPE_NULL;
 295     krb5_data_zero(&s.salt.saltvalue);
 296
 297     *kvno = 0;
 298     kcm_internal_ccache(context, ccache, &ccdata);
 299     s.password = newpw;
 300
 301     /* Do an AS-REQ to determine salt and key version number */
 302     ret = krb5_copy_principal(context, ccache->client, &creds.client);
 303     if (ret)
 304         return ret;
 305
 306     /* Yes, get a ticket to ourselves */
 307     ret = krb5_copy_principal(context, ccache->client, &creds.server);
 308     if (ret) {
 309         krb5_free_principal(context, creds.client);
 310         return ret;
 311     }
 312
 313     ret = krb5_get_in_tkt(context,
 314                           options,
 315                           NULL,
 316                           etypes,
 317                           NULL,
 318                           kcm_password_key_proc,
 319                           &s,
 320                           NULL,
 321                           NULL,
 322                           &creds,
 323                           &ccdata,
 324                           &reply);
 325     if (ret) {
 326         kcm_log(0, "Failed to get self ticket for principal %s: %s",
 327                 cpn, krb5_get_err_text(context, ret));
 328         krb5_free_salt(context, s.salt);
 329     } else {
 330         *salt = s.salt; /* retrieve stashed salt */
 331         if (reply.kdc_rep.enc_part.kvno != NULL)
 332             *kvno = *(reply.kdc_rep.enc_part.kvno);
 333     }
 334     /* ccache may have been modified but it will get trashed anyway */
 335
 336     krb5_free_creds_contents(context, &creds);
 337     krb5_free_kdc_rep(context, &reply);
 338
 339     return ret;
 340 }
 341
 342 static krb5_error_code
 343 update_keytab_entry(krb5_context context,
 344                     kcm_ccache ccache,
 345                     krb5_enctype etype,
 346                     char *cpn,
 347                     char *spn,
 348                     char *newpw,
 349                     krb5_salt salt,
 350                     unsigned kvno)
 351 {
 352     krb5_error_code ret;
 353     krb5_keytab_entry entry;
 354     krb5_data pw;
 355
 356     memset(&entry, 0, sizeof(entry));
 357
 358     pw.data = (char *)newpw;
 359     pw.length = strlen(newpw);
 360
 361     ret = krb5_string_to_key_data_salt(context, etype, pw,
 362                                        salt, &entry.keyblock);
 363     if (ret) {
 364         kcm_log(0, "String to key conversion failed for principal %s "
 365                 "and etype %d: %s",
 366                 cpn, etype, krb5_get_err_text(context, ret));
 367         return ret;
 368     }
 369
 370     if (spn == NULL) {
 371         ret = krb5_copy_principal(context, ccache->client,
 372                                   &entry.principal);
 373         if (ret) {
 374             kcm_log(0, "Failed to copy principal name %s: %s",
 375                     cpn, krb5_get_err_text(context, ret));
 376             return ret;
 377         }
 378     } else {
 379         ret = krb5_parse_name(context, spn, &entry.principal);
 380         if (ret) {
 381             kcm_log(0, "Failed to parse SPN alias %s: %s",
 382                     spn, krb5_get_err_text(context, ret));
 383             return ret;
 384         }
 385     }
 386
 387     entry.vno = kvno;
 388     entry.timestamp = time(NULL);
 389
 390     ret = krb5_kt_add_entry(context, ccache->key.keytab, &entry);
 391     if (ret) {
 392         kcm_log(0, "Failed to update keytab for principal %s "
 393                 "and etype %d: %s",
 394                 cpn, etype, krb5_get_err_text(context, ret));
 395     }
 396
 397     krb5_kt_free_entry(context, &entry);
 398
 399     return ret;
 400 }
 401
 402 static krb5_error_code
 403 update_keytab_entries(krb5_context context,
 404                       kcm_ccache ccache,
 405                       krb5_enctype *etypes,
 406                       char *cpn,
 407                       char *spn,
 408                       char *newpw,
 409                       krb5_salt salt,
 410                       unsigned kvno)
 411 {
 412     krb5_error_code ret = 0;
 413     int i;
 414
 415     for (i = 0; etypes[i] != ETYPE_NULL; i++) {
 416         ret = update_keytab_entry(context, ccache, etypes[i],
 417                                   cpn, spn, newpw, salt, kvno);
 418         if (ret)
 419             break;
 420     }
 421
 422     return ret;
 423 }
 424
 425 static void
 426 generate_random_pw(krb5_context context,
 427                    unsigned char *buf,
 428                    size_t bufsiz)
 429 {
 430     unsigned char x[512], *p;
 431     size_t i;
 432
 433     memset(x, 0, sizeof(x));
 434     krb5_generate_random_block(x, sizeof(x));
 435     p = x;
 436
 437     for (i = 0; i < bufsiz; i++) {
 438         while (isprint(*p) == 0)
 439             p++;
 440
 441         if (p - x >= sizeof(x)) {
 442             krb5_generate_random_block(x, sizeof(x));
 443             p = x;
 444         }
 445         buf[i] = *p++;
 446     }
 447     buf[bufsiz - 1] = '\0';
 448     memset(x, 0, sizeof(x));
 449 }
 450
 451 static krb5_error_code
 452 change_pw_and_update_keytab(krb5_context context,
 453                             kcm_ccache ccache)
 454 {
 455     char newpw[121];
 456     krb5_error_code ret;
 457     unsigned kvno;
 458     krb5_salt salt;
 459     krb5_enctype *etypes = NULL;
 460     int i;
 461     char *cpn = NULL;
 462     char **spns = NULL;
 463
 464     krb5_data_zero(&salt.saltvalue);
 465
 466     ret = krb5_unparse_name(context, ccache->client, &cpn);
 467     if (ret) {
 468         kcm_log(0, "Failed to unparse name: %s",
 469                 krb5_get_err_text(context, ret));
 470         goto out;
 471     }
 472
 473     ret = krb5_get_default_in_tkt_etypes(context, &etypes);
 474     if (ret) {
 475         kcm_log(0, "Failed to determine default encryption types: %s",
 476                 krb5_get_err_text(context, ret));
 477         goto out;
 478     }
 479
 480     /* Generate a random password (there is no set keys protocol) */
 481     generate_random_pw(context, newpw, sizeof(newpw));
 482
 483     /* Change it */
 484     ret = change_pw(context, ccache, cpn, newpw);
 485     if (ret)
 486         goto out;
 487
 488     /* Do an AS-REQ to determine salt and key version number */
 489     ret = get_salt_and_kvno(context, ccache, etypes, cpn, newpw,
 490                             &salt, &kvno);
 491     if (ret) {
 492         kcm_log(0, "Failed to determine salting principal for principal %s: %s",
 493                 cpn, krb5_get_err_text(context, ret));
 494         goto out;
 495     }
 496
 497     /* Add canonical name */
 498     ret = update_keytab_entries(context, ccache, etypes, cpn,
 499                                 NULL, newpw, salt, kvno);
 500     if (ret)
 501         goto out;
 502
 503     /* Add SPN aliases, if any */
 504     spns = krb5_config_get_strings(context, NULL, "kcm",
 505                                    "system_ccache", "spn_aliases", NULL);
 506     if (spns != NULL) {
 507         for (i = 0; spns[i] != NULL; i++) {
 508             ret = update_keytab_entries(context, ccache, etypes, cpn,
 509                                         spns[i], newpw, salt, kvno);
 510             if (ret)
 511                 goto out;
 512         }
 513     }
 514
 515     kcm_log(0, "Changed expired password for principal %s in cache %s",
 516             cpn, ccache->name);
 517
 518 out:
 519     if (cpn != NULL)
 520         free(cpn);
 521     if (spns != NULL)
 522         krb5_config_free_strings(spns);
 523     if (etypes != NULL)
 524         free(etypes);
 525     krb5_free_salt(context, salt);
 526     memset(newpw, 0, sizeof(newpw));
 527
 528     return ret;
 529 }
 530