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