source4/auth/kerberos/kerberos_util.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Kerberos utility functions for GENSEC
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25 #include "system/kerberos.h"
  26 #include "system/time.h"
  27 #include "system/network.h"
  28 #include "auth/kerberos/kerberos.h"
  29 #include "auth/auth.h"
  30
  31 struct principal_container {
  32         struct smb_krb5_context *smb_krb5_context;
  33         krb5_principal principal;
  34 };
  35
  36 static int free_principal(void *ptr) {
  37         struct principal_container *pc = ptr;
  38         /* current heimdal - 0.6.3, which we need anyway, fixes segfaults here */
  39         krb5_free_principal(pc->smb_krb5_context->krb5_context, pc->principal);
  40
  41         return 0;
  42 }
  43
  44 krb5_error_code salt_principal_from_credentials(TALLOC_CTX *parent_ctx,
  45                                                 struct cli_credentials *machine_account,
  46                                                 struct smb_krb5_context *smb_krb5_context,
  47                                                 krb5_principal *salt_princ)
  48 {
  49         krb5_error_code ret;
  50         char *machine_username;
  51         char *salt_body;
  52         char *lower_realm;
  53         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
  54         if (!mem_ctx) {
  55                 return ENOMEM;
  56         }
  57
  58         machine_username = talloc_strdup(mem_ctx, cli_credentials_get_username(machine_account));
  59
  60         if (!machine_username) {
  61                 talloc_free(mem_ctx);
  62                 return ENOMEM;
  63         }
  64
  65         if (machine_username[strlen(machine_username)-1] == '$') {
  66                 machine_username[strlen(machine_username)-1] = '\0';
  67         }
  68         lower_realm = strlower_talloc(mem_ctx, cli_credentials_get_realm(machine_account));
  69         if (!lower_realm) {
  70                 talloc_free(mem_ctx);
  71                 return ENOMEM;
  72         }
  73
  74         salt_body = talloc_asprintf(mem_ctx, "%s.%s", machine_username,
  75                                     lower_realm);
  76         if (!salt_body) {
  77                 talloc_free(mem_ctx);
  78                 return ENOMEM;
  79         }
  80
  81         ret = krb5_make_principal(smb_krb5_context->krb5_context, salt_princ,
  82                                   cli_credentials_get_realm(machine_account),
  83                                   "host", salt_body, NULL);
  84
  85         if (ret == 0) {
  86                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
  87                 mem_ctx->principal = *salt_princ;
  88                 talloc_set_destructor(mem_ctx, free_principal);
  89         }
  90         return ret;
  91 }
  92
  93 krb5_error_code principal_from_credentials(TALLOC_CTX *parent_ctx,
  94                                            struct cli_credentials *credentials,
  95                                            struct smb_krb5_context *smb_krb5_context,
  96                                            krb5_principal *princ)
  97 {
  98         krb5_error_code ret;
  99         const char *princ_string;
 100         struct principal_container *mem_ctx = talloc(parent_ctx, struct principal_container);
 101         if (!mem_ctx) {
 102                 return ENOMEM;
 103         }
 104
 105         princ_string = cli_credentials_get_principal(credentials, mem_ctx);
 106
 107         if (!princ_string) {
 108                 talloc_free(mem_ctx);
 109                 princ = NULL;
 110                 return 0;
 111         }
 112
 113         ret = krb5_parse_name(smb_krb5_context->krb5_context,
 114                               princ_string, princ);
 115
 116         if (ret == 0) {
 117                 mem_ctx->smb_krb5_context = talloc_reference(mem_ctx, smb_krb5_context);
 118                 mem_ctx->principal = *princ;
 119                 talloc_set_destructor(mem_ctx, free_principal);
 120         }
 121         return ret;
 122 }
 123
 124 /**
 125  * Return a freshly allocated ccache (destroyed by destructor on child
 126  * of parent_ctx), for a given set of client credentials
 127  */
 128
 129  krb5_error_code kinit_to_ccache(TALLOC_CTX *parent_ctx,
 130                                  struct cli_credentials *credentials,
 131                                  struct smb_krb5_context *smb_krb5_context,
 132                                  krb5_ccache ccache)
 133 {
 134         krb5_error_code ret;
 135         const char *password;
 136         time_t kdc_time = 0;
 137         krb5_principal princ;
 138
 139         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 140
 141         if (!mem_ctx) {
 142                 return ENOMEM;
 143         }
 144
 145         ret = principal_from_credentials(mem_ctx, credentials, smb_krb5_context, &princ);
 146         if (ret) {
 147                 talloc_free(mem_ctx);
 148                 return ret;
 149         }
 150
 151         password = cli_credentials_get_password(credentials);
 152
 153         if (password) {
 154                 ret = kerberos_kinit_password_cc(smb_krb5_context->krb5_context, ccache,
 155                                                  princ,
 156                                                  password, NULL, &kdc_time);
 157         } else {
 158                 /* No password available, try to use a keyblock instead */
 159
 160                 krb5_keyblock keyblock;
 161                 const struct samr_Password *mach_pwd;
 162                 mach_pwd = cli_credentials_get_nt_hash(credentials, mem_ctx);
 163                 if (!mach_pwd) {
 164                         talloc_free(mem_ctx);
 165                         DEBUG(1, ("kinit_to_ccache: No password available for kinit\n"));
 166                         return EINVAL;
 167                 }
 168                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 169                                          ENCTYPE_ARCFOUR_HMAC,
 170                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 171                                          &keyblock);
 172
 173                 if (ret == 0) {
 174                         ret = kerberos_kinit_keyblock_cc(smb_krb5_context->krb5_context, ccache,
 175                                                          princ,
 176                                                          &keyblock, NULL, &kdc_time);
 177                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &keyblock);
 178                 }
 179         }
 180
 181         /* cope with ticket being in the future due to clock skew */
 182         if ((unsigned)kdc_time > time(NULL)) {
 183                 time_t t = time(NULL);
 184                 int time_offset =(unsigned)kdc_time-t;
 185                 DEBUG(4,("Advancing clock by %d seconds to cope with clock skew\n", time_offset));
 186                 krb5_set_real_time(smb_krb5_context->krb5_context, t + time_offset + 1, 0);
 187         }
 188
 189         if (ret == KRB5KRB_AP_ERR_SKEW || ret == KRB5_KDCREP_SKEW) {
 190                 DEBUG(1,("kinit for %s failed (%s)\n",
 191                          cli_credentials_get_principal(credentials, mem_ctx),
 192                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 193                                                     ret, mem_ctx)));
 194                 talloc_free(mem_ctx);
 195                 return ret;
 196         }
 197         if (ret) {
 198                 DEBUG(1,("kinit for %s failed (%s)\n",
 199                          cli_credentials_get_principal(credentials, mem_ctx),
 200                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 201                                                     ret, mem_ctx)));
 202                 talloc_free(mem_ctx);
 203                 return ret;
 204         }
 205         return 0;
 206 }
 207
 208 static int free_keytab(void *ptr) {
 209         struct keytab_container *ktc = ptr;
 210         krb5_kt_close(ktc->smb_krb5_context->krb5_context, ktc->keytab);
 211
 212         return 0;
 213 }
 214
 215  int create_memory_keytab(TALLOC_CTX *parent_ctx,
 216                           struct cli_credentials *machine_account,
 217                           struct smb_krb5_context *smb_krb5_context,
 218                           struct keytab_container **keytab_container)
 219 {
 220         krb5_error_code ret;
 221         const char *password_s;
 222         char *old_secret;
 223         krb5_data password;
 224         int i, kvno;
 225         krb5_enctype *enctypes;
 226         krb5_principal salt_princ;
 227         krb5_principal princ;
 228         krb5_keytab keytab;
 229
 230         TALLOC_CTX *mem_ctx = talloc_new(parent_ctx);
 231         if (!mem_ctx) {
 232                 return ENOMEM;
 233         }
 234
 235         *keytab_container = talloc(mem_ctx, struct keytab_container);
 236
 237         ret = krb5_kt_resolve(smb_krb5_context->krb5_context, "MEMORY:", &keytab);
 238         if (ret) {
 239                 DEBUG(1,("failed to generate a new krb5 keytab: %s\n",
 240                          error_message(ret)));
 241                 talloc_free(mem_ctx);
 242                 return ret;
 243         }
 244
 245         (*keytab_container)->smb_krb5_context = talloc_reference(*keytab_container, smb_krb5_context);
 246         (*keytab_container)->keytab = keytab;
 247
 248         talloc_set_destructor(*keytab_container, free_keytab);
 249
 250         ret = salt_principal_from_credentials(mem_ctx, machine_account,
 251                                               smb_krb5_context,
 252                                               &salt_princ);
 253         if (ret) {
 254                 DEBUG(1,("create_memory_keytab: maksing salt principal failed (%s)\n",
 255                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 256                                                     ret, mem_ctx)));
 257                 talloc_free(mem_ctx);
 258                 return ret;
 259         }
 260
 261         ret = principal_from_credentials(mem_ctx, machine_account, smb_krb5_context, &princ);
 262         if (ret) {
 263                 DEBUG(1,("create_memory_keytab: maksing krb5 principal failed (%s)\n",
 264                          smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 265                                                     ret, mem_ctx)));
 266                 talloc_free(mem_ctx);
 267                 return ret;
 268         }
 269
 270         password_s = cli_credentials_get_password(machine_account);
 271         if (!password_s) {
 272                 /* If we don't have the plaintext password, try for
 273                  * the MD4 password hash */
 274
 275                 krb5_keytab_entry entry;
 276                 const struct samr_Password *mach_pwd;
 277                 mach_pwd = cli_credentials_get_nt_hash(machine_account, mem_ctx);
 278                 if (!mach_pwd) {
 279                         talloc_free(mem_ctx);
 280                         DEBUG(1, ("create_memory_keytab: Domain trust informaton for account %s not available\n",
 281                                   cli_credentials_get_principal(machine_account, mem_ctx)));
 282                         return EINVAL;
 283                 }
 284                 ret = krb5_keyblock_init(smb_krb5_context->krb5_context,
 285                                          ENCTYPE_ARCFOUR_HMAC,
 286                                          mach_pwd->hash, sizeof(mach_pwd->hash),
 287                                          &entry.keyblock);
 288                 if (ret) {
 289                         DEBUG(1, ("create_memory_keytab: krb5_keyblock_init failed: %s\n",
 290                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 291                                                              ret, mem_ctx)));
 292                         return ret;
 293                 }
 294
 295                 entry.principal = princ;
 296                 entry.vno       = cli_credentials_get_kvno(machine_account);
 297                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 298                 if (ret) {
 299                         DEBUG(1, ("Failed to add ARCFOUR_HMAC (only) entry for %s to keytab: %s",
 300                                   cli_credentials_get_principal(machine_account, mem_ctx),
 301                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 302                                                              ret, mem_ctx)));
 303                         talloc_free(mem_ctx);
 304                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 305                         return ret;
 306                 }
 307
 308                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 309
 310                 talloc_steal(parent_ctx, *keytab_container);
 311                 talloc_free(mem_ctx);
 312                 return 0;
 313         }
 314
 315         /* good, we actually have the real plaintext */
 316
 317         ret = get_kerberos_allowed_etypes(smb_krb5_context->krb5_context,
 318                                           &enctypes);
 319         if (ret) {
 320                 DEBUG(1,("create_memory_keytab: getting encrption types failed (%s)\n",
 321                          error_message(ret)));
 322                 talloc_free(mem_ctx);
 323                 return ret;
 324         }
 325
 326         password.data = discard_const_p(char *, password_s);
 327         password.length = strlen(password_s);
 328         kvno = cli_credentials_get_kvno(machine_account);
 329
 330         for (i=0; enctypes[i]; i++) {
 331                 krb5_keytab_entry entry;
 332                 ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 333                                                       salt_princ, &password, &entry.keyblock, enctypes[i]);
 334                 if (ret) {
 335                         talloc_free(mem_ctx);
 336                         return ret;
 337                 }
 338
 339                 entry.principal = princ;
 340                 entry.vno       = kvno;
 341                 ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 342                 if (ret) {
 343                         DEBUG(1, ("Failed to add entry for %s to keytab: %s",
 344                                   cli_credentials_get_principal(machine_account, mem_ctx),
 345                                   smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 346                                                              ret, mem_ctx)));
 347                         talloc_free(mem_ctx);
 348                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 349                         return ret;
 350                 }
 351
 352                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 353         }
 354
 355         old_secret = cli_credentials_get_old_password(machine_account);
 356         if (kvno != 0 && old_secret) {
 357                 password.data = discard_const_p(char *, old_secret);
 358                 password.length = strlen(old_secret);
 359
 360                 for (i=0; enctypes[i]; i++) {
 361                         krb5_keytab_entry entry;
 362                         ret = create_kerberos_key_from_string(smb_krb5_context->krb5_context,
 363                                                               salt_princ, &password, &entry.keyblock, enctypes[i]);
 364                         if (ret) {
 365                                 talloc_free(mem_ctx);
 366                                 return ret;
 367                         }
 368
 369                         entry.principal = princ;
 370                         entry.vno       = kvno - 1;
 371                         ret = krb5_kt_add_entry(smb_krb5_context->krb5_context, keytab, &entry);
 372                         if (ret) {
 373                                 DEBUG(1, ("Failed to add 'old password' entry for %s to keytab: %s",
 374                                           cli_credentials_get_principal(machine_account, mem_ctx),
 375                                           smb_get_krb5_error_message(smb_krb5_context->krb5_context,
 376                                                                      ret, mem_ctx)));
 377                                 talloc_free(mem_ctx);
 378                                 krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 379                                 return ret;
 380                         }
 381
 382                         krb5_free_keyblock_contents(smb_krb5_context->krb5_context, &entry.keyblock);
 383                 }
 384         }
 385
 386         free_kerberos_etypes(smb_krb5_context->krb5_context, enctypes);
 387
 388         talloc_steal(parent_ctx, *keytab_container);
 389         talloc_free(mem_ctx);
 390         return 0;
 391 }
 392
 393