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 #ifdef HAVE_KRB5
  27
  28 #include "librpc/gen_ndr/ndr_krb5pac.h"
  29 #include "auth/kerberos/pac_utils.h"
  30
  31 krb5_error_code check_pac_checksum(DATA_BLOB pac_data,
  32                                           struct PAC_SIGNATURE_DATA *sig,
  33                                           krb5_context context,
  34                                           const krb5_keyblock *keyblock)
  35 {
  36         krb5_error_code ret;
  37         krb5_checksum cksum;
  38         krb5_keyusage usage = 0;
  39         krb5_boolean checksum_valid = false;
  40         krb5_data input;
  41
  42 #ifdef HAVE_CHECKSUM_IN_KRB5_CHECKSUM /* Heimdal */
  43         cksum.cksumtype = (krb5_cksumtype)sig->type;
  44         cksum.checksum.length   = sig->signature.length;
  45         cksum.checksum.data     = sig->signature.data;
  46 #else /* MIT */
  47         cksum.checksum_type     = (krb5_cksumtype)sig->type;
  48         cksum.length            = sig->signature.length;
  49         cksum.contents          = sig->signature.data;
  50 #endif
  51
  52 #ifdef HAVE_KRB5_KU_OTHER_CKSUM /* Heimdal */
  53         usage = KRB5_KU_OTHER_CKSUM;
  54 #elif defined(HAVE_KRB5_KEYUSAGE_APP_DATA_CKSUM) /* MIT */
  55         usage = KRB5_KEYUSAGE_APP_DATA_CKSUM;
  56 #else
  57 #error UNKNOWN_KRB5_KEYUSAGE
  58 #endif
  59
  60         input.data = (char *)pac_data.data;
  61         input.length = pac_data.length;
  62
  63         ret = krb5_c_verify_checksum(context,
  64                                      keyblock,
  65                                      usage,
  66                                      &input,
  67                                      &cksum,
  68                                      &checksum_valid);
  69         if (!checksum_valid) {
  70                 ret = KRB5KRB_AP_ERR_BAD_INTEGRITY;
  71         }
  72         if (ret){
  73                 DEBUG(2,("check_pac_checksum: PAC Verification failed: %s (%d)\n",
  74                         error_message(ret), ret));
  75                 return ret;
  76         }
  77
  78         return ret;
  79 }
  80
  81 /**
  82 * @brief Decode a blob containing a NDR encoded PAC structure
  83 *
  84 * @param mem_ctx          - The memory context
  85 * @param pac_data_blob    - The data blob containing the NDR encoded data
  86 * @param context          - The Kerberos Context
  87 * @param service_keyblock - The Service Key used to verify the checksum
  88 * @param client_principal - The client principal
  89 * @param tgs_authtime     - The ticket timestamp
  90 * @param pac_data_out     - [out] The decoded PAC
  91 *
  92 * @return - A NTSTATUS error code
  93 */
  94 NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
  95                              DATA_BLOB pac_data_blob,
  96                              krb5_context context,
  97                              const krb5_keyblock *krbtgt_keyblock,
  98                              const krb5_keyblock *service_keyblock,
  99                              krb5_const_principal client_principal,
 100                              time_t tgs_authtime,
 101                              struct PAC_DATA **pac_data_out)
 102 {
 103         NTSTATUS status;
 104         enum ndr_err_code ndr_err;
 105         krb5_error_code ret;
 106         DATA_BLOB modified_pac_blob;
 107
 108         NTTIME tgs_authtime_nttime;
 109         int i;
 110
 111         struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
 112         struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
 113         struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL;
 114         struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL;
 115         struct PAC_LOGON_NAME *logon_name = NULL;
 116         struct PAC_LOGON_INFO *logon_info = NULL;
 117         struct PAC_DATA *pac_data = NULL;
 118         struct PAC_DATA_RAW *pac_data_raw = NULL;
 119
 120         DATA_BLOB *srv_sig_blob = NULL;
 121         DATA_BLOB *kdc_sig_blob = NULL;
 122
 123         bool bool_ret;
 124
 125         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 126         if (!tmp_ctx) {
 127                 return NT_STATUS_NO_MEMORY;
 128         }
 129
 130         if (pac_data_out) {
 131                 *pac_data_out = NULL;
 132         }
 133
 134         pac_data = talloc(tmp_ctx, struct PAC_DATA);
 135         pac_data_raw = talloc(tmp_ctx, struct PAC_DATA_RAW);
 136         kdc_sig_wipe = talloc(tmp_ctx, struct PAC_SIGNATURE_DATA);
 137         srv_sig_wipe = talloc(tmp_ctx, struct PAC_SIGNATURE_DATA);
 138         if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) {
 139                 talloc_free(tmp_ctx);
 140                 return NT_STATUS_NO_MEMORY;
 141         }
 142
 143         ndr_err = ndr_pull_struct_blob(&pac_data_blob, pac_data, pac_data,
 144                        (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
 145         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 146                 status = ndr_map_error2ntstatus(ndr_err);
 147                 DEBUG(0,("can't parse the PAC: %s\n",
 148                         nt_errstr(status)));
 149                 talloc_free(tmp_ctx);
 150                 return status;
 151         }
 152
 153         if (pac_data->num_buffers < 4) {
 154                 /* we need logon_ingo, service_key and kdc_key */
 155                 DEBUG(0,("less than 4 PAC buffers\n"));
 156                 talloc_free(tmp_ctx);
 157                 return NT_STATUS_INVALID_PARAMETER;
 158         }
 159
 160         ndr_err = ndr_pull_struct_blob(
 161                                 &pac_data_blob, pac_data_raw, pac_data_raw,
 162                                 (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW);
 163         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 164                 status = ndr_map_error2ntstatus(ndr_err);
 165                 DEBUG(0,("can't parse the PAC: %s\n",
 166                         nt_errstr(status)));
 167                 talloc_free(tmp_ctx);
 168                 return status;
 169         }
 170
 171         if (pac_data_raw->num_buffers < 4) {
 172                 /* we need logon_ingo, service_key and kdc_key */
 173                 DEBUG(0,("less than 4 PAC buffers\n"));
 174                 talloc_free(tmp_ctx);
 175                 return NT_STATUS_INVALID_PARAMETER;
 176         }
 177
 178         if (pac_data->num_buffers != pac_data_raw->num_buffers) {
 179                 /* we need logon_ingo, service_key and kdc_key */
 180                 DEBUG(0, ("misparse! PAC_DATA has %d buffers while "
 181                           "PAC_DATA_RAW has %d\n", pac_data->num_buffers,
 182                           pac_data_raw->num_buffers));
 183                 talloc_free(tmp_ctx);
 184                 return NT_STATUS_INVALID_PARAMETER;
 185         }
 186
 187         for (i=0; i < pac_data->num_buffers; i++) {
 188                 struct PAC_BUFFER *data_buf = &pac_data->buffers[i];
 189                 struct PAC_BUFFER_RAW *raw_buf = &pac_data_raw->buffers[i];
 190
 191                 if (data_buf->type != raw_buf->type) {
 192                         DEBUG(0, ("misparse! PAC_DATA buffer %d has type "
 193                                   "%d while PAC_DATA_RAW has %d\n", i,
 194                                   data_buf->type, raw_buf->type));
 195                         talloc_free(tmp_ctx);
 196                         return NT_STATUS_INVALID_PARAMETER;
 197                 }
 198                 switch (data_buf->type) {
 199                 case PAC_TYPE_LOGON_INFO:
 200                         if (!data_buf->info) {
 201                                 break;
 202                         }
 203                         logon_info = data_buf->info->logon_info.info;
 204                         break;
 205                 case PAC_TYPE_SRV_CHECKSUM:
 206                         if (!data_buf->info) {
 207                                 break;
 208                         }
 209                         srv_sig_ptr = &data_buf->info->srv_cksum;
 210                         srv_sig_blob = &raw_buf->info->remaining;
 211                         break;
 212                 case PAC_TYPE_KDC_CHECKSUM:
 213                         if (!data_buf->info) {
 214                                 break;
 215                         }
 216                         kdc_sig_ptr = &data_buf->info->kdc_cksum;
 217                         kdc_sig_blob = &raw_buf->info->remaining;
 218                         break;
 219                 case PAC_TYPE_LOGON_NAME:
 220                         logon_name = &data_buf->info->logon_name;
 221                         break;
 222                 default:
 223                         break;
 224                 }
 225         }
 226
 227         if (!logon_info) {
 228                 DEBUG(0,("PAC no logon_info\n"));
 229                 talloc_free(tmp_ctx);
 230                 return NT_STATUS_INVALID_PARAMETER;
 231         }
 232
 233         if (!logon_name) {
 234                 DEBUG(0,("PAC no logon_name\n"));
 235                 talloc_free(tmp_ctx);
 236                 return NT_STATUS_INVALID_PARAMETER;
 237         }
 238
 239         if (!srv_sig_ptr || !srv_sig_blob) {
 240                 DEBUG(0,("PAC no srv_key\n"));
 241                 talloc_free(tmp_ctx);
 242                 return NT_STATUS_INVALID_PARAMETER;
 243         }
 244
 245         if (!kdc_sig_ptr || !kdc_sig_blob) {
 246                 DEBUG(0,("PAC no kdc_key\n"));
 247                 talloc_free(tmp_ctx);
 248                 return NT_STATUS_INVALID_PARAMETER;
 249         }
 250
 251         /* Find and zero out the signatures,
 252          * as required by the signing algorithm */
 253
 254         /* We find the data blobs above,
 255          * now we parse them to get at the exact portion we should zero */
 256         ndr_err = ndr_pull_struct_blob(
 257                         kdc_sig_blob, kdc_sig_wipe, kdc_sig_wipe,
 258                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 259         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 260                 status = ndr_map_error2ntstatus(ndr_err);
 261                 DEBUG(0,("can't parse the KDC signature: %s\n",
 262                         nt_errstr(status)));
 263                 talloc_free(tmp_ctx);
 264                 return status;
 265         }
 266
 267         ndr_err = ndr_pull_struct_blob(
 268                         srv_sig_blob, srv_sig_wipe, srv_sig_wipe,
 269                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 270         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 271                 status = ndr_map_error2ntstatus(ndr_err);
 272                 DEBUG(0,("can't parse the SRV signature: %s\n",
 273                         nt_errstr(status)));
 274                 talloc_free(tmp_ctx);
 275                 return status;
 276         }
 277
 278         /* Now zero the decoded structure */
 279         memset(kdc_sig_wipe->signature.data,
 280                 '\0', kdc_sig_wipe->signature.length);
 281         memset(srv_sig_wipe->signature.data,
 282                 '\0', srv_sig_wipe->signature.length);
 283
 284         /* and reencode, back into the same place it came from */
 285         ndr_err = ndr_push_struct_blob(
 286                         kdc_sig_blob, pac_data_raw, kdc_sig_wipe,
 287                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 288         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 289                 status = ndr_map_error2ntstatus(ndr_err);
 290                 DEBUG(0,("can't repack the KDC signature: %s\n",
 291                         nt_errstr(status)));
 292                 talloc_free(tmp_ctx);
 293                 return status;
 294         }
 295         ndr_err = ndr_push_struct_blob(
 296                         srv_sig_blob, pac_data_raw, srv_sig_wipe,
 297                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 298         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 299                 status = ndr_map_error2ntstatus(ndr_err);
 300                 DEBUG(0,("can't repack the SRV signature: %s\n",
 301                         nt_errstr(status)));
 302                 talloc_free(tmp_ctx);
 303                 return status;
 304         }
 305
 306         /* push out the whole structure, but now with zero'ed signatures */
 307         ndr_err = ndr_push_struct_blob(
 308                         &modified_pac_blob, pac_data_raw, pac_data_raw,
 309                         (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW);
 310         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 311                 status = ndr_map_error2ntstatus(ndr_err);
 312                 DEBUG(0,("can't repack the RAW PAC: %s\n",
 313                         nt_errstr(status)));
 314                 talloc_free(tmp_ctx);
 315                 return status;
 316         }
 317
 318         if (service_keyblock) {
 319                 /* verify by service_key */
 320                 ret = check_pac_checksum(modified_pac_blob, srv_sig_ptr,
 321                                          context,
 322                                          service_keyblock);
 323                 if (ret) {
 324                         DEBUG(5, ("PAC Decode: Failed to verify the service "
 325                                   "signature: %s\n", error_message(ret)));
 326                         return NT_STATUS_ACCESS_DENIED;
 327                 }
 328
 329                 if (krbtgt_keyblock) {
 330                         /* verify the service key checksum by krbtgt_key */
 331                         ret = check_pac_checksum(srv_sig_ptr->signature, kdc_sig_ptr,
 332                                                  context, krbtgt_keyblock);
 333                         if (ret) {
 334                                 DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
 335                                           smb_get_krb5_error_message(context, ret, tmp_ctx)));
 336                                 talloc_free(tmp_ctx);
 337                                 return NT_STATUS_ACCESS_DENIED;
 338                         }
 339                 }
 340         }
 341
 342         if (tgs_authtime) {
 343                 /* Convert to NT time, so as not to loose accuracy in comparison */
 344                 unix_to_nt_time(&tgs_authtime_nttime, tgs_authtime);
 345
 346                 if (tgs_authtime_nttime != logon_name->logon_time) {
 347                         DEBUG(2, ("PAC Decode: "
 348                                   "Logon time mismatch between ticket and PAC!\n"));
 349                         DEBUG(2, ("PAC Decode: PAC: %s\n",
 350                                   nt_time_string(tmp_ctx, logon_name->logon_time)));
 351                         DEBUG(2, ("PAC Decode: Ticket: %s\n",
 352                                   nt_time_string(tmp_ctx, tgs_authtime_nttime)));
 353                         talloc_free(tmp_ctx);
 354                         return NT_STATUS_ACCESS_DENIED;
 355                 }
 356         }
 357
 358         if (client_principal) {
 359                 char *client_principal_string;
 360                 ret = krb5_unparse_name_flags(context, client_principal,
 361                                               KRB5_PRINCIPAL_UNPARSE_NO_REALM|KRB5_PRINCIPAL_UNPARSE_DISPLAY,
 362                                               &client_principal_string);
 363                 if (ret) {
 364                         DEBUG(2, ("Could not unparse name from ticket to match with name from PAC: [%s]:%s\n",
 365                                   logon_name->account_name, error_message(ret)));
 366                         talloc_free(tmp_ctx);
 367                         return NT_STATUS_INVALID_PARAMETER;
 368                 }
 369
 370                 bool_ret = strcmp(client_principal_string, logon_name->account_name) == 0;
 371
 372                 if (!bool_ret) {
 373                         DEBUG(2, ("Name in PAC [%s] does not match principal name "
 374                                   "in ticket [%s]\n",
 375                                   logon_name->account_name,
 376                                   client_principal_string));
 377                         SAFE_FREE(client_principal_string);
 378                         talloc_free(tmp_ctx);
 379                         return NT_STATUS_ACCESS_DENIED;
 380                 }
 381                 SAFE_FREE(client_principal_string);
 382
 383         }
 384
 385         DEBUG(3,("Found account name from PAC: %s [%s]\n",
 386                  logon_info->info3.base.account_name.string,
 387                  logon_info->info3.base.full_name.string));
 388
 389         DEBUG(10,("Successfully validated Kerberos PAC\n"));
 390
 391         if (DEBUGLEVEL >= 10) {
 392                 const char *s;
 393                 s = NDR_PRINT_STRUCT_STRING(tmp_ctx, PAC_DATA, pac_data);
 394                 if (s) {
 395                         DEBUGADD(10,("%s\n", s));
 396                 }
 397         }
 398
 399         if (pac_data_out) {
 400                 *pac_data_out = talloc_steal(mem_ctx, pac_data);
 401         }
 402
 403         return NT_STATUS_OK;
 404 }
 405
 406 NTSTATUS kerberos_pac_logon_info(TALLOC_CTX *mem_ctx,
 407                                  DATA_BLOB blob,
 408                                  krb5_context context,
 409                                  const krb5_keyblock *krbtgt_keyblock,
 410                                  const krb5_keyblock *service_keyblock,
 411                                  krb5_const_principal client_principal,
 412                                  time_t tgs_authtime,
 413                                  struct PAC_LOGON_INFO **logon_info)
 414 {
 415         NTSTATUS nt_status;
 416         struct PAC_DATA *pac_data;
 417         int i;
 418         nt_status = kerberos_decode_pac(mem_ctx,
 419                                         blob,
 420                                         context,
 421                                         krbtgt_keyblock,
 422                                         service_keyblock,
 423                                         client_principal,
 424                                         tgs_authtime,
 425                                         &pac_data);
 426         if (!NT_STATUS_IS_OK(nt_status)) {
 427                 return nt_status;
 428         }
 429
 430         *logon_info = NULL;
 431         for (i=0; i < pac_data->num_buffers; i++) {
 432                 if (pac_data->buffers[i].type != PAC_TYPE_LOGON_INFO) {
 433                         continue;
 434                 }
 435                 *logon_info = pac_data->buffers[i].info->logon_info.info;
 436         }
 437         if (!*logon_info) {
 438                 return NT_STATUS_INVALID_PARAMETER;
 439         }
 440         return NT_STATUS_OK;
 441 }
 442
 443 #endif