auth/kerberos/kerberos_pac.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    kerberos authorization data (PAC) utility library
   4    Copyright (C) Jim McDonough <jmcd@us.ibm.com> 2003
   5    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
   6    Copyright (C) Andrew Tridgell 2001
   7    Copyright (C) Luke Howard 2002-2003
   8    Copyright (C) Stefan Metzmacher 2004-2005
   9    Copyright (C) Guenther Deschner 2005,2007,2008
  10
  11    This program is free software; you can redistribute it and/or modify
  12    it under the terms of the GNU General Public License as published by
  13    the Free Software Foundation; either version 3 of the License, or
  14    (at your option) any later version.
  15
  16    This program is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19    GNU General Public License for more details.
  20
  21    You should have received a copy of the GNU General Public License
  22    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 #include "includes.h"
  26
  27 #undef DBGC_CLASS
  28 #define DBGC_CLASS DBGC_AUTH
  29
  30 #ifdef HAVE_KRB5
  31
  32 #include "librpc/gen_ndr/ndr_krb5pac.h"
  33 #include "librpc/gen_ndr/auth.h"
  34 #include "auth/common_auth.h"
  35 #include "auth/kerberos/pac_utils.h"
  36
  37 krb5_error_code check_pac_checksum(DATA_BLOB pac_data,
  38                                           struct PAC_SIGNATURE_DATA *sig,
  39                                           krb5_context context,
  40                                           const krb5_keyblock *keyblock)
  41 {
  42         krb5_error_code ret;
  43         krb5_checksum cksum;
  44         krb5_keyusage usage = 0;
  45         krb5_boolean checksum_valid = false;
  46         krb5_data input;
  47
  48         switch (sig->type) {
  49         case CKSUMTYPE_HMAC_MD5:
  50                 /* ignores the key type */
  51                 break;
  52         case CKSUMTYPE_HMAC_SHA1_96_AES_256:
  53                 if (KRB5_KEY_TYPE(keyblock) != ENCTYPE_AES256_CTS_HMAC_SHA1_96) {
  54                         return EINVAL;
  55                 }
  56                 /* ok */
  57                 break;
  58         case CKSUMTYPE_HMAC_SHA1_96_AES_128:
  59                 if (KRB5_KEY_TYPE(keyblock) != ENCTYPE_AES128_CTS_HMAC_SHA1_96) {
  60                         return EINVAL;
  61                 }
  62                 /* ok */
  63                 break;
  64         default:
  65                 DEBUG(2,("check_pac_checksum: Checksum Type %d is not supported\n",
  66                         (int)sig->type));
  67                 return EINVAL;
  68         }
  69
  70 #ifdef HAVE_CHECKSUM_IN_KRB5_CHECKSUM /* Heimdal */
  71         cksum.cksumtype = (krb5_cksumtype)sig->type;
  72         cksum.checksum.length   = sig->signature.length;
  73         cksum.checksum.data     = sig->signature.data;
  74 #else /* MIT */
  75         cksum.checksum_type     = (krb5_cksumtype)sig->type;
  76         cksum.length            = sig->signature.length;
  77         cksum.contents          = sig->signature.data;
  78 #endif
  79
  80 #ifdef HAVE_KRB5_KU_OTHER_CKSUM /* Heimdal */
  81         usage = KRB5_KU_OTHER_CKSUM;
  82 #elif defined(HAVE_KRB5_KEYUSAGE_APP_DATA_CKSUM) /* MIT */
  83         usage = KRB5_KEYUSAGE_APP_DATA_CKSUM;
  84 #else
  85 #error UNKNOWN_KRB5_KEYUSAGE
  86 #endif
  87
  88         input.data = (char *)pac_data.data;
  89         input.length = pac_data.length;
  90
  91         ret = krb5_c_verify_checksum(context,
  92                                      keyblock,
  93                                      usage,
  94                                      &input,
  95                                      &cksum,
  96                                      &checksum_valid);
  97         if (!checksum_valid) {
  98                 ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
  99         }
 100         if (ret){
 101                 DEBUG(2,("check_pac_checksum: PAC Verification failed: %s (%d)\n",
 102                         error_message(ret), ret));
 103                 return ret;
 104         }
 105
 106         return ret;
 107 }
 108
 109 /**
 110 * @brief Decode a blob containing a NDR encoded PAC structure
 111 *
 112 * @param mem_ctx          - The memory context
 113 * @param pac_data_blob    - The data blob containing the NDR encoded data
 114 * @param context          - The Kerberos Context
 115 * @param service_keyblock - The Service Key used to verify the checksum
 116 * @param client_principal - The client principal
 117 * @param tgs_authtime     - The ticket timestamp
 118 * @param pac_data_out     - [out] The decoded PAC
 119 *
 120 * @return - A NTSTATUS error code
 121 */
 122 NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
 123                              DATA_BLOB pac_data_blob,
 124                              krb5_context context,
 125                              const krb5_keyblock *krbtgt_keyblock,
 126                              const krb5_keyblock *service_keyblock,
 127                              krb5_const_principal client_principal,
 128                              time_t tgs_authtime,
 129                              struct PAC_DATA **pac_data_out)
 130 {
 131         NTSTATUS status;
 132         enum ndr_err_code ndr_err;
 133         krb5_error_code ret;
 134         DATA_BLOB modified_pac_blob;
 135
 136         NTTIME tgs_authtime_nttime;
 137         int i;
 138
 139         struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
 140         struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
 141         struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL;
 142         struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL;
 143         struct PAC_LOGON_NAME *logon_name = NULL;
 144         struct PAC_LOGON_INFO *logon_info = NULL;
 145         struct PAC_DATA *pac_data = NULL;
 146         struct PAC_DATA_RAW *pac_data_raw = NULL;
 147
 148         DATA_BLOB *srv_sig_blob = NULL;
 149         DATA_BLOB *kdc_sig_blob = NULL;
 150
 151         bool bool_ret;
 152
 153         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 154         if (!tmp_ctx) {
 155                 return NT_STATUS_NO_MEMORY;
 156         }
 157
 158         if (pac_data_out) {
 159                 *pac_data_out = NULL;
 160         }
 161
 162         pac_data = talloc(tmp_ctx, struct PAC_DATA);
 163         pac_data_raw = talloc(tmp_ctx, struct PAC_DATA_RAW);
 164         kdc_sig_wipe = talloc(tmp_ctx, struct PAC_SIGNATURE_DATA);
 165         srv_sig_wipe = talloc(tmp_ctx, struct PAC_SIGNATURE_DATA);
 166         if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) {
 167                 talloc_free(tmp_ctx);
 168                 return NT_STATUS_NO_MEMORY;
 169         }
 170
 171         ndr_err = ndr_pull_struct_blob(&pac_data_blob, pac_data, pac_data,
 172                        (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
 173         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 174                 status = ndr_map_error2ntstatus(ndr_err);
 175                 DEBUG(0,("can't parse the PAC: %s\n",
 176                         nt_errstr(status)));
 177                 talloc_free(tmp_ctx);
 178                 return status;
 179         }
 180
 181         if (pac_data->num_buffers < 4) {
 182                 /* we need logon_ingo, service_key and kdc_key */
 183                 DEBUG(0,("less than 4 PAC buffers\n"));
 184                 talloc_free(tmp_ctx);
 185                 return NT_STATUS_INVALID_PARAMETER;
 186         }
 187
 188         ndr_err = ndr_pull_struct_blob(
 189                                 &pac_data_blob, pac_data_raw, pac_data_raw,
 190                                 (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW);
 191         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 192                 status = ndr_map_error2ntstatus(ndr_err);
 193                 DEBUG(0,("can't parse the PAC: %s\n",
 194                         nt_errstr(status)));
 195                 talloc_free(tmp_ctx);
 196                 return status;
 197         }
 198
 199         if (pac_data_raw->num_buffers < 4) {
 200                 /* we need logon_ingo, service_key and kdc_key */
 201                 DEBUG(0,("less than 4 PAC buffers\n"));
 202                 talloc_free(tmp_ctx);
 203                 return NT_STATUS_INVALID_PARAMETER;
 204         }
 205
 206         if (pac_data->num_buffers != pac_data_raw->num_buffers) {
 207                 /* we need logon_ingo, service_key and kdc_key */
 208                 DEBUG(0, ("misparse! PAC_DATA has %d buffers while "
 209                           "PAC_DATA_RAW has %d\n", pac_data->num_buffers,
 210                           pac_data_raw->num_buffers));
 211                 talloc_free(tmp_ctx);
 212                 return NT_STATUS_INVALID_PARAMETER;
 213         }
 214
 215         for (i=0; i < pac_data->num_buffers; i++) {
 216                 struct PAC_BUFFER *data_buf = &pac_data->buffers[i];
 217                 struct PAC_BUFFER_RAW *raw_buf = &pac_data_raw->buffers[i];
 218
 219                 if (data_buf->type != raw_buf->type) {
 220                         DEBUG(0, ("misparse! PAC_DATA buffer %d has type "
 221                                   "%d while PAC_DATA_RAW has %d\n", i,
 222                                   data_buf->type, raw_buf->type));
 223                         talloc_free(tmp_ctx);
 224                         return NT_STATUS_INVALID_PARAMETER;
 225                 }
 226                 switch (data_buf->type) {
 227                 case PAC_TYPE_LOGON_INFO:
 228                         if (!data_buf->info) {
 229                                 break;
 230                         }
 231                         logon_info = data_buf->info->logon_info.info;
 232                         break;
 233                 case PAC_TYPE_SRV_CHECKSUM:
 234                         if (!data_buf->info) {
 235                                 break;
 236                         }
 237                         srv_sig_ptr = &data_buf->info->srv_cksum;
 238                         srv_sig_blob = &raw_buf->info->remaining;
 239                         break;
 240                 case PAC_TYPE_KDC_CHECKSUM:
 241                         if (!data_buf->info) {
 242                                 break;
 243                         }
 244                         kdc_sig_ptr = &data_buf->info->kdc_cksum;
 245                         kdc_sig_blob = &raw_buf->info->remaining;
 246                         break;
 247                 case PAC_TYPE_LOGON_NAME:
 248                         logon_name = &data_buf->info->logon_name;
 249                         break;
 250                 default:
 251                         break;
 252                 }
 253         }
 254
 255         if (!logon_info) {
 256                 DEBUG(0,("PAC no logon_info\n"));
 257                 talloc_free(tmp_ctx);
 258                 return NT_STATUS_INVALID_PARAMETER;
 259         }
 260
 261         if (!logon_name) {
 262                 DEBUG(0,("PAC no logon_name\n"));
 263                 talloc_free(tmp_ctx);
 264                 return NT_STATUS_INVALID_PARAMETER;
 265         }
 266
 267         if (!srv_sig_ptr || !srv_sig_blob) {
 268                 DEBUG(0,("PAC no srv_key\n"));
 269                 talloc_free(tmp_ctx);
 270                 return NT_STATUS_INVALID_PARAMETER;
 271         }
 272
 273         if (!kdc_sig_ptr || !kdc_sig_blob) {
 274                 DEBUG(0,("PAC no kdc_key\n"));
 275                 talloc_free(tmp_ctx);
 276                 return NT_STATUS_INVALID_PARAMETER;
 277         }
 278
 279         /* Find and zero out the signatures,
 280          * as required by the signing algorithm */
 281
 282         /* We find the data blobs above,
 283          * now we parse them to get at the exact portion we should zero */
 284         ndr_err = ndr_pull_struct_blob(
 285                         kdc_sig_blob, kdc_sig_wipe, kdc_sig_wipe,
 286                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 287         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 288                 status = ndr_map_error2ntstatus(ndr_err);
 289                 DEBUG(0,("can't parse the KDC signature: %s\n",
 290                         nt_errstr(status)));
 291                 talloc_free(tmp_ctx);
 292                 return status;
 293         }
 294
 295         ndr_err = ndr_pull_struct_blob(
 296                         srv_sig_blob, srv_sig_wipe, srv_sig_wipe,
 297                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 298         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 299                 status = ndr_map_error2ntstatus(ndr_err);
 300                 DEBUG(0,("can't parse the SRV signature: %s\n",
 301                         nt_errstr(status)));
 302                 talloc_free(tmp_ctx);
 303                 return status;
 304         }
 305
 306         /* Now zero the decoded structure */
 307         memset(kdc_sig_wipe->signature.data,
 308                 '\0', kdc_sig_wipe->signature.length);
 309         memset(srv_sig_wipe->signature.data,
 310                 '\0', srv_sig_wipe->signature.length);
 311
 312         /* and reencode, back into the same place it came from */
 313         ndr_err = ndr_push_struct_blob(
 314                         kdc_sig_blob, pac_data_raw, kdc_sig_wipe,
 315                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 316         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 317                 status = ndr_map_error2ntstatus(ndr_err);
 318                 DEBUG(0,("can't repack the KDC signature: %s\n",
 319                         nt_errstr(status)));
 320                 talloc_free(tmp_ctx);
 321                 return status;
 322         }
 323         ndr_err = ndr_push_struct_blob(
 324                         srv_sig_blob, pac_data_raw, srv_sig_wipe,
 325                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 326         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 327                 status = ndr_map_error2ntstatus(ndr_err);
 328                 DEBUG(0,("can't repack the SRV signature: %s\n",
 329                         nt_errstr(status)));
 330                 talloc_free(tmp_ctx);
 331                 return status;
 332         }
 333
 334         /* push out the whole structure, but now with zero'ed signatures */
 335         ndr_err = ndr_push_struct_blob(
 336                         &modified_pac_blob, pac_data_raw, pac_data_raw,
 337                         (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW);
 338         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 339                 status = ndr_map_error2ntstatus(ndr_err);
 340                 DEBUG(0,("can't repack the RAW PAC: %s\n",
 341                         nt_errstr(status)));
 342                 talloc_free(tmp_ctx);
 343                 return status;
 344         }
 345
 346         if (service_keyblock) {
 347                 /* verify by service_key */
 348                 ret = check_pac_checksum(modified_pac_blob, srv_sig_ptr,
 349                                          context,
 350                                          service_keyblock);
 351                 if (ret) {
 352                         DEBUG(5, ("PAC Decode: Failed to verify the service "
 353                                   "signature: %s\n", error_message(ret)));
 354                         return NT_STATUS_ACCESS_DENIED;
 355                 }
 356
 357                 if (krbtgt_keyblock) {
 358                         /* verify the service key checksum by krbtgt_key */
 359                         ret = check_pac_checksum(srv_sig_ptr->signature, kdc_sig_ptr,
 360                                                  context, krbtgt_keyblock);
 361                         if (ret) {
 362                                 DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
 363                                           smb_get_krb5_error_message(context, ret, tmp_ctx)));
 364                                 talloc_free(tmp_ctx);
 365                                 return NT_STATUS_ACCESS_DENIED;
 366                         }
 367                 }
 368         }
 369
 370         if (tgs_authtime) {
 371                 /* Convert to NT time, so as not to loose accuracy in comparison */
 372                 unix_to_nt_time(&tgs_authtime_nttime, tgs_authtime);
 373
 374                 if (tgs_authtime_nttime != logon_name->logon_time) {
 375                         DEBUG(2, ("PAC Decode: "
 376                                   "Logon time mismatch between ticket and PAC!\n"));
 377                         DEBUG(2, ("PAC Decode: PAC: %s\n",
 378                                   nt_time_string(tmp_ctx, logon_name->logon_time)));
 379                         DEBUG(2, ("PAC Decode: Ticket: %s\n",
 380                                   nt_time_string(tmp_ctx, tgs_authtime_nttime)));
 381                         talloc_free(tmp_ctx);
 382                         return NT_STATUS_ACCESS_DENIED;
 383                 }
 384         }
 385
 386         if (client_principal) {
 387                 char *client_principal_string;
 388                 ret = krb5_unparse_name_flags(context, client_principal,
 389                                               KRB5_PRINCIPAL_UNPARSE_NO_REALM|KRB5_PRINCIPAL_UNPARSE_DISPLAY,
 390                                               &client_principal_string);
 391                 if (ret) {
 392                         DEBUG(2, ("Could not unparse name from ticket to match with name from PAC: [%s]:%s\n",
 393                                   logon_name->account_name, error_message(ret)));
 394                         talloc_free(tmp_ctx);
 395                         return NT_STATUS_INVALID_PARAMETER;
 396                 }
 397
 398                 bool_ret = strcmp(client_principal_string, logon_name->account_name) == 0;
 399
 400                 if (!bool_ret) {
 401                         DEBUG(2, ("Name in PAC [%s] does not match principal name "
 402                                   "in ticket [%s]\n",
 403                                   logon_name->account_name,
 404                                   client_principal_string));
 405                         SAFE_FREE(client_principal_string);
 406                         talloc_free(tmp_ctx);
 407                         return NT_STATUS_ACCESS_DENIED;
 408                 }
 409                 SAFE_FREE(client_principal_string);
 410
 411         }
 412
 413         DEBUG(3,("Found account name from PAC: %s [%s]\n",
 414                  logon_info->info3.base.account_name.string,
 415                  logon_info->info3.base.full_name.string));
 416
 417         DEBUG(10,("Successfully validated Kerberos PAC\n"));
 418
 419         if (DEBUGLEVEL >= 10) {
 420                 const char *s;
 421                 s = NDR_PRINT_STRUCT_STRING(tmp_ctx, PAC_DATA, pac_data);
 422                 if (s) {
 423                         DEBUGADD(10,("%s\n", s));
 424                 }
 425         }
 426
 427         if (pac_data_out) {
 428                 *pac_data_out = talloc_steal(mem_ctx, pac_data);
 429         }
 430
 431         return NT_STATUS_OK;
 432 }
 433
 434 NTSTATUS kerberos_pac_logon_info(TALLOC_CTX *mem_ctx,
 435                                  DATA_BLOB blob,
 436                                  krb5_context context,
 437                                  const krb5_keyblock *krbtgt_keyblock,
 438                                  const krb5_keyblock *service_keyblock,
 439                                  krb5_const_principal client_principal,
 440                                  time_t tgs_authtime,
 441                                  struct PAC_LOGON_INFO **logon_info)
 442 {
 443         NTSTATUS nt_status;
 444         struct PAC_DATA *pac_data;
 445         int i;
 446         nt_status = kerberos_decode_pac(mem_ctx,
 447                                         blob,
 448                                         context,
 449                                         krbtgt_keyblock,
 450                                         service_keyblock,
 451                                         client_principal,
 452                                         tgs_authtime,
 453                                         &pac_data);
 454         if (!NT_STATUS_IS_OK(nt_status)) {
 455                 return nt_status;
 456         }
 457
 458         *logon_info = NULL;
 459         for (i=0; i < pac_data->num_buffers; i++) {
 460                 if (pac_data->buffers[i].type != PAC_TYPE_LOGON_INFO) {
 461                         continue;
 462                 }
 463                 *logon_info = pac_data->buffers[i].info->logon_info.info;
 464         }
 465         if (!*logon_info) {
 466                 return NT_STATUS_INVALID_PARAMETER;
 467         }
 468         return NT_STATUS_OK;
 469 }
 470
 471 static NTSTATUS auth4_context_fetch_PAC_DATA_CTR(
 472                                 struct auth4_context *auth_ctx,
 473                                 TALLOC_CTX *mem_ctx,
 474                                 struct smb_krb5_context *smb_krb5_context,
 475                                 DATA_BLOB *pac_blob,
 476                                 const char *princ_name,
 477                                 const struct tsocket_address *remote_address,
 478                                 uint32_t session_info_flags,
 479                                 struct auth_session_info **session_info)
 480 {
 481         struct PAC_DATA_CTR *pac_data_ctr = NULL;
 482         NTSTATUS status;
 483
 484         if (pac_blob == NULL) {
 485                 return NT_STATUS_NO_IMPERSONATION_TOKEN;
 486         }
 487
 488         pac_data_ctr = talloc_zero(mem_ctx, struct PAC_DATA_CTR);
 489         if (pac_data_ctr == NULL) {
 490                 status = NT_STATUS_NO_MEMORY;
 491                 goto fail;
 492         }
 493
 494         status = kerberos_decode_pac(pac_data_ctr,
 495                                      *pac_blob,
 496                                      NULL,
 497                                      NULL,
 498                                      NULL,
 499                                      NULL,
 500                                      0,
 501                                      &pac_data_ctr->pac_data);
 502         if (!NT_STATUS_IS_OK(status)) {
 503                 goto fail;
 504         }
 505
 506         pac_data_ctr->pac_blob = data_blob_talloc(pac_data_ctr,
 507                                                   pac_blob->data,
 508                                                   pac_blob->length);
 509         if (pac_data_ctr->pac_blob.length != pac_blob->length) {
 510                 status = NT_STATUS_NO_MEMORY;
 511                 goto fail;
 512         }
 513
 514         *session_info = talloc_zero(mem_ctx, struct auth_session_info);
 515         if (*session_info == NULL) {
 516                 status = NT_STATUS_NO_MEMORY;
 517                 goto fail;
 518         }
 519
 520         TALLOC_FREE(auth_ctx->private_data);
 521         auth_ctx->private_data = talloc_move(auth_ctx, &pac_data_ctr);
 522
 523         return NT_STATUS_OK;
 524
 525 fail:
 526         TALLOC_FREE(pac_data_ctr);
 527
 528         return status;
 529 }
 530
 531 struct auth4_context *auth4_context_for_PAC_DATA_CTR(TALLOC_CTX *mem_ctx)
 532 {
 533         struct auth4_context *auth_ctx = NULL;
 534
 535         auth_ctx = talloc_zero(mem_ctx, struct auth4_context);
 536         if (auth_ctx == NULL) {
 537                 return NULL;
 538         }
 539         auth_ctx->generate_session_info_pac = auth4_context_fetch_PAC_DATA_CTR;
 540
 541         return auth_ctx;
 542 }
 543
 544 struct PAC_DATA_CTR *auth4_context_get_PAC_DATA_CTR(struct auth4_context *auth_ctx,
 545                                                     TALLOC_CTX *mem_ctx)
 546 {
 547         struct PAC_DATA_CTR *p = NULL;
 548         SMB_ASSERT(auth_ctx->generate_session_info_pac == auth4_context_fetch_PAC_DATA_CTR);
 549         p = talloc_get_type_abort(auth_ctx->private_data, struct PAC_DATA_CTR);
 550         auth_ctx->private_data = NULL;
 551         return talloc_move(mem_ctx, &p);
 552 }
 553
 554 #endif