source4/auth/kerberos/kerberos_pac.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Create and parse the krb5 PAC
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2004-2005
   7    Copyright (C) Andrew Tridgell 2001
   8    Copyright (C) Luke Howard 2002-2003
   9    Copyright (C) Stefan Metzmacher 2004-2005
  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 2 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
  22    You should have received a copy of the GNU General Public License
  23    along with this program; if not, write to the Free Software
  24    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25 */
  26
  27 #include "includes.h"
  28 #include "system/kerberos.h"
  29 #include "auth/kerberos/kerberos.h"
  30 #include "librpc/gen_ndr/ndr_krb5pac.h"
  31 #include "lib/ldb/include/ldb.h"
  32 #include "auth/auth_sam.h"
  33
  34 static krb5_error_code check_pac_checksum(TALLOC_CTX *mem_ctx,
  35                                           DATA_BLOB pac_data,
  36                                           struct PAC_SIGNATURE_DATA *sig,
  37                                           krb5_context context,
  38                                           const krb5_keyblock *keyblock)
  39 {
  40         krb5_error_code ret;
  41         krb5_crypto crypto;
  42         Checksum cksum;
  43
  44         cksum.cksumtype         = (CKSUMTYPE)sig->type;
  45         cksum.checksum.length   = sig->signature.length;
  46         cksum.checksum.data     = sig->signature.data;
  47
  48         ret = krb5_crypto_init(context,
  49                                keyblock,
  50                                0,
  51                                &crypto);
  52         if (ret) {
  53                 DEBUG(0,("krb5_crypto_init() failed: %s\n",
  54                           smb_get_krb5_error_message(context, ret, mem_ctx)));
  55                 return ret;
  56         }
  57         ret = krb5_verify_checksum(context,
  58                                    crypto,
  59                                    KRB5_KU_OTHER_CKSUM,
  60                                    pac_data.data,
  61                                    pac_data.length,
  62                                    &cksum);
  63         krb5_crypto_destroy(context, crypto);
  64
  65         return ret;
  66 }
  67
  68  NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
  69                               struct PAC_DATA **pac_data_out,
  70                               DATA_BLOB blob,
  71                               krb5_context context,
  72                               const krb5_keyblock *krbtgt_keyblock,
  73                               const krb5_keyblock *service_keyblock,
  74                               krb5_const_principal client_principal,
  75                               time_t tgs_authtime,
  76                               krb5_error_code *k5ret)
  77 {
  78         krb5_error_code ret;
  79         NTSTATUS status;
  80         struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
  81         struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
  82         struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL;
  83         struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL;
  84         struct PAC_LOGON_INFO *logon_info = NULL;
  85         struct PAC_LOGON_NAME *logon_name = NULL;
  86         struct PAC_DATA *pac_data;
  87         struct PAC_DATA_RAW *pac_data_raw;
  88
  89         DATA_BLOB *srv_sig_blob = NULL;
  90         DATA_BLOB *kdc_sig_blob = NULL;
  91
  92         DATA_BLOB modified_pac_blob;
  93         NTTIME tgs_authtime_nttime;
  94         krb5_principal client_principal_pac;
  95         int i;
  96
  97         krb5_clear_error_string(context);
  98
  99         if (k5ret) {
 100                 *k5ret = KRB5_PARSE_MALFORMED;
 101         }
 102
 103         pac_data = talloc(mem_ctx, struct PAC_DATA);
 104         pac_data_raw = talloc(mem_ctx, struct PAC_DATA_RAW);
 105         kdc_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
 106         srv_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
 107         if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) {
 108                 if (k5ret) {
 109                         *k5ret = ENOMEM;
 110                 }
 111                 return NT_STATUS_NO_MEMORY;
 112         }
 113
 114         status = ndr_pull_struct_blob(&blob, pac_data, pac_data,
 115                                       (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
 116         if (!NT_STATUS_IS_OK(status)) {
 117                 DEBUG(0,("can't parse the PAC\n"));
 118                 return status;
 119         }
 120
 121         if (pac_data->num_buffers < 4) {
 122                 /* we need logon_ingo, service_key and kdc_key */
 123                 DEBUG(0,("less than 4 PAC buffers\n"));
 124                 return NT_STATUS_INVALID_PARAMETER;
 125         }
 126
 127         status = ndr_pull_struct_blob(&blob, pac_data_raw, pac_data_raw,
 128                                       (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW);
 129         if (!NT_STATUS_IS_OK(status)) {
 130                 DEBUG(0,("can't parse the PAC\n"));
 131                 return status;
 132         }
 133
 134         if (pac_data_raw->num_buffers < 4) {
 135                 /* we need logon_ingo, service_key and kdc_key */
 136                 DEBUG(0,("less than 4 PAC buffers\n"));
 137                 return NT_STATUS_INVALID_PARAMETER;
 138         }
 139
 140         if (pac_data->num_buffers != pac_data_raw->num_buffers) {
 141                 /* we need logon_ingo, service_key and kdc_key */
 142                 DEBUG(0,("misparse!  PAC_DATA has %d buffers while PAC_DATA_RAW has %d\n",
 143                          pac_data->num_buffers, pac_data_raw->num_buffers));
 144                 return NT_STATUS_INVALID_PARAMETER;
 145         }
 146
 147         for (i=0; i < pac_data->num_buffers; i++) {
 148                 if (pac_data->buffers[i].type != pac_data_raw->buffers[i].type) {
 149                         DEBUG(0,("misparse!  PAC_DATA buffer %d has type %d while PAC_DATA_RAW has %d\n",
 150                                  i, pac_data->buffers[i].type, pac_data->buffers[i].type));
 151                         return NT_STATUS_INVALID_PARAMETER;
 152                 }
 153                 switch (pac_data->buffers[i].type) {
 154                         case PAC_TYPE_LOGON_INFO:
 155                                 if (!pac_data->buffers[i].info) {
 156                                         break;
 157                                 }
 158                                 logon_info = pac_data->buffers[i].info->logon_info.info;
 159                                 break;
 160                         case PAC_TYPE_SRV_CHECKSUM:
 161                                 if (!pac_data->buffers[i].info) {
 162                                         break;
 163                                 }
 164                                 srv_sig_ptr = &pac_data->buffers[i].info->srv_cksum;
 165                                 srv_sig_blob = &pac_data_raw->buffers[i].info->remaining;
 166                                 break;
 167                         case PAC_TYPE_KDC_CHECKSUM:
 168                                 if (!pac_data->buffers[i].info) {
 169                                         break;
 170                                 }
 171                                 kdc_sig_ptr = &pac_data->buffers[i].info->kdc_cksum;
 172                                 kdc_sig_blob = &pac_data_raw->buffers[i].info->remaining;
 173                                 break;
 174                         case PAC_TYPE_LOGON_NAME:
 175                                 logon_name = &pac_data->buffers[i].info->logon_name;
 176                                 break;
 177                         default:
 178                                 break;
 179                 }
 180         }
 181
 182         if (!logon_info) {
 183                 DEBUG(0,("PAC no logon_info\n"));
 184                 return NT_STATUS_INVALID_PARAMETER;
 185         }
 186
 187         if (!logon_name) {
 188                 DEBUG(0,("PAC no logon_name\n"));
 189                 return NT_STATUS_INVALID_PARAMETER;
 190         }
 191
 192         if (!srv_sig_ptr || !srv_sig_blob) {
 193                 DEBUG(0,("PAC no srv_key\n"));
 194                 return NT_STATUS_INVALID_PARAMETER;
 195         }
 196
 197         if (!kdc_sig_ptr || !kdc_sig_blob) {
 198                 DEBUG(0,("PAC no kdc_key\n"));
 199                 return NT_STATUS_INVALID_PARAMETER;
 200         }
 201
 202         /* Find and zero out the signatures, as required by the signing algorithm */
 203
 204         /* We find the data blobs above, now we parse them to get at the exact portion we should zero */
 205         status = ndr_pull_struct_blob(kdc_sig_blob, kdc_sig_wipe, kdc_sig_wipe,
 206                                       (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 207         if (!NT_STATUS_IS_OK(status)) {
 208                 DEBUG(0,("can't parse the KDC signature\n"));
 209                 return status;
 210         }
 211
 212         status = ndr_pull_struct_blob(srv_sig_blob, srv_sig_wipe, srv_sig_wipe,
 213                                       (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 214         if (!NT_STATUS_IS_OK(status)) {
 215                 DEBUG(0,("can't parse the SRV signature\n"));
 216                 return status;
 217         }
 218
 219         /* Now zero the decoded structure */
 220         memset(kdc_sig_wipe->signature.data, '\0', kdc_sig_wipe->signature.length);
 221         memset(srv_sig_wipe->signature.data, '\0', srv_sig_wipe->signature.length);
 222
 223         /* and reencode, back into the same place it came from */
 224         status = ndr_push_struct_blob(kdc_sig_blob, pac_data_raw, kdc_sig_wipe,
 225                                       (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 226         if (!NT_STATUS_IS_OK(status)) {
 227                 DEBUG(0,("can't repack the KDC signature\n"));
 228                 return status;
 229         }
 230         status = ndr_push_struct_blob(srv_sig_blob, pac_data_raw, srv_sig_wipe,
 231                                       (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 232         if (!NT_STATUS_IS_OK(status)) {
 233                 DEBUG(0,("can't repack the SRV signature\n"));
 234                 return status;
 235         }
 236
 237         /* push out the whole structure, but now with zero'ed signatures */
 238         status = ndr_push_struct_blob(&modified_pac_blob, pac_data_raw, pac_data_raw,
 239                                          (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW);
 240         if (!NT_STATUS_IS_OK(status)) {
 241                 DEBUG(0,("can't repack the RAW PAC\n"));
 242                 return status;
 243         }
 244
 245         /* verify by service_key */
 246         ret = check_pac_checksum(mem_ctx,
 247                                  modified_pac_blob, srv_sig_ptr,
 248                                  context,
 249                                  service_keyblock);
 250         if (ret) {
 251                 DEBUG(1, ("PAC Decode: Failed to verify the service signature: %s\n",
 252                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 253                 if (k5ret) {
 254                         *k5ret = ret;
 255                 }
 256                 return NT_STATUS_ACCESS_DENIED;
 257         }
 258
 259         if (krbtgt_keyblock) {
 260                 ret = check_pac_checksum(mem_ctx,
 261                                             srv_sig_ptr->signature, kdc_sig_ptr,
 262                                             context, krbtgt_keyblock);
 263                 if (ret) {
 264                         DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
 265                                   smb_get_krb5_error_message(context, ret, mem_ctx)));
 266                         if (k5ret) {
 267                                 *k5ret = ret;
 268                         }
 269                         return NT_STATUS_ACCESS_DENIED;
 270                 }
 271         }
 272
 273         /* Convert to NT time, so as not to loose accuracy in comparison */
 274         unix_to_nt_time(&tgs_authtime_nttime, tgs_authtime);
 275
 276         if (tgs_authtime_nttime != logon_name->logon_time) {
 277                 DEBUG(2, ("PAC Decode: Logon time mismatch between ticket and PAC!\n"));
 278                 DEBUG(2, ("PAC Decode: PAC: %s\n", nt_time_string(mem_ctx, logon_name->logon_time)));
 279                 DEBUG(2, ("PAC Decode: Ticket: %s\n", nt_time_string(mem_ctx, tgs_authtime_nttime)));
 280                 return NT_STATUS_ACCESS_DENIED;
 281         }
 282
 283         ret = krb5_parse_name_flags(context, logon_name->account_name, KRB5_PRINCIPAL_PARSE_NO_REALM,
 284                                     &client_principal_pac);
 285         if (ret) {
 286                 DEBUG(2, ("Could not parse name from incoming PAC: [%s]: %s\n",
 287                           logon_name->account_name,
 288                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 289                 if (k5ret) {
 290                         *k5ret = ret;
 291                 }
 292                 return NT_STATUS_INVALID_PARAMETER;
 293         }
 294
 295         if (!krb5_principal_compare_any_realm(context, client_principal, client_principal_pac)) {
 296                 DEBUG(2, ("Name in PAC [%s] does not match principal name in ticket\n",
 297                           logon_name->account_name));
 298                 return NT_STATUS_ACCESS_DENIED;
 299         }
 300
 301 #if 0
 302         if (strcasecmp(logon_info->info3.base.account_name.string,
 303                        "Administrator")== 0) {
 304                 file_save("tmp_pac_data-admin.dat",blob.data,blob.length);
 305         }
 306 #endif
 307
 308         DEBUG(3,("Found account name from PAC: %s [%s]\n",
 309                  logon_info->info3.base.account_name.string,
 310                  logon_info->info3.base.full_name.string));
 311         *pac_data_out = pac_data;
 312
 313         return status;
 314 }
 315
 316 _PUBLIC_  NTSTATUS kerberos_pac_logon_info(TALLOC_CTX *mem_ctx,
 317                                   struct PAC_LOGON_INFO **logon_info,
 318                                   DATA_BLOB blob,
 319                                   krb5_context context,
 320                                   const krb5_keyblock *krbtgt_keyblock,
 321                                   const krb5_keyblock *service_keyblock,
 322                                   krb5_const_principal client_principal,
 323                                   time_t tgs_authtime,
 324                                   krb5_error_code *k5ret)
 325 {
 326         NTSTATUS nt_status;
 327         struct PAC_DATA *pac_data;
 328         int i;
 329         nt_status = kerberos_decode_pac(mem_ctx, &pac_data,
 330                                         blob,
 331                                         context,
 332                                         krbtgt_keyblock,
 333                                         service_keyblock,
 334                                         client_principal,
 335                                         tgs_authtime,
 336                                         k5ret);
 337         if (!NT_STATUS_IS_OK(nt_status)) {
 338                 return nt_status;
 339         }
 340
 341         *logon_info = NULL;
 342         for (i=0; i < pac_data->num_buffers; i++) {
 343                 if (pac_data->buffers[i].type != PAC_TYPE_LOGON_INFO) {
 344                         continue;
 345                 }
 346                 *logon_info = pac_data->buffers[i].info->logon_info.info;
 347         }
 348         if (!*logon_info) {
 349                 return NT_STATUS_INVALID_PARAMETER;
 350         }
 351         return NT_STATUS_OK;
 352 }
 353
 354 static krb5_error_code make_pac_checksum(TALLOC_CTX *mem_ctx,
 355                                          DATA_BLOB *pac_data,
 356                                          struct PAC_SIGNATURE_DATA *sig,
 357                                          krb5_context context,
 358                                          const krb5_keyblock *keyblock)
 359 {
 360         krb5_error_code ret;
 361         krb5_crypto crypto;
 362         Checksum cksum;
 363
 364
 365         ret = krb5_crypto_init(context,
 366                                keyblock,
 367                                0,
 368                                &crypto);
 369         if (ret) {
 370                 DEBUG(0,("krb5_crypto_init() failed: %s\n",
 371                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 372                 return ret;
 373         }
 374         ret = krb5_create_checksum(context,
 375                                    crypto,
 376                                    KRB5_KU_OTHER_CKSUM,
 377                                    0,
 378                                    pac_data->data,
 379                                    pac_data->length,
 380                                    &cksum);
 381         if (ret) {
 382                 DEBUG(2, ("PAC Verification failed: %s\n",
 383                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 384         }
 385
 386         krb5_crypto_destroy(context, crypto);
 387
 388         if (ret) {
 389                 return ret;
 390         }
 391
 392         sig->type = cksum.cksumtype;
 393         sig->signature = data_blob_talloc(mem_ctx, cksum.checksum.data, cksum.checksum.length);
 394         free_Checksum(&cksum);
 395
 396         return 0;
 397 }
 398
 399  krb5_error_code kerberos_encode_pac(TALLOC_CTX *mem_ctx,
 400                                     struct PAC_DATA *pac_data,
 401                                     krb5_context context,
 402                                     const krb5_keyblock *krbtgt_keyblock,
 403                                     const krb5_keyblock *service_keyblock,
 404                                     DATA_BLOB *pac)
 405 {
 406         NTSTATUS nt_status;
 407         krb5_error_code ret;
 408         DATA_BLOB zero_blob = data_blob(NULL, 0);
 409         DATA_BLOB tmp_blob = data_blob(NULL, 0);
 410         struct PAC_SIGNATURE_DATA *kdc_checksum = NULL;
 411         struct PAC_SIGNATURE_DATA *srv_checksum = NULL;
 412         int i;
 413
 414         /* First, just get the keytypes filled in (and lengths right, eventually) */
 415         for (i=0; i < pac_data->num_buffers; i++) {
 416                 if (pac_data->buffers[i].type != PAC_TYPE_KDC_CHECKSUM) {
 417                         continue;
 418                 }
 419                 kdc_checksum = &pac_data->buffers[i].info->kdc_cksum,
 420                 ret = make_pac_checksum(mem_ctx, &zero_blob,
 421                                         kdc_checksum,
 422                                         context, krbtgt_keyblock);
 423                 if (ret) {
 424                         DEBUG(2, ("making krbtgt PAC checksum failed: %s\n",
 425                                   smb_get_krb5_error_message(context, ret, mem_ctx)));
 426                         talloc_free(pac_data);
 427                         return ret;
 428                 }
 429         }
 430
 431         for (i=0; i < pac_data->num_buffers; i++) {
 432                 if (pac_data->buffers[i].type != PAC_TYPE_SRV_CHECKSUM) {
 433                         continue;
 434                 }
 435                 srv_checksum = &pac_data->buffers[i].info->srv_cksum;
 436                 ret = make_pac_checksum(mem_ctx, &zero_blob,
 437                                         srv_checksum,
 438                                         context, service_keyblock);
 439                 if (ret) {
 440                         DEBUG(2, ("making service PAC checksum failed: %s\n",
 441                                   smb_get_krb5_error_message(context, ret, mem_ctx)));
 442                         talloc_free(pac_data);
 443                         return ret;
 444                 }
 445         }
 446
 447         if (!kdc_checksum) {
 448                 DEBUG(2, ("Invalid PAC constructed for signing, no KDC checksum present!"));
 449                 return EINVAL;
 450         }
 451         if (!srv_checksum) {
 452                 DEBUG(2, ("Invalid PAC constructed for signing, no SRV checksum present!"));
 453                 return EINVAL;
 454         }
 455
 456         /* But wipe out the actual signatures */
 457         memset(kdc_checksum->signature.data, '\0', kdc_checksum->signature.length);
 458         memset(srv_checksum->signature.data, '\0', srv_checksum->signature.length);
 459
 460         nt_status = ndr_push_struct_blob(&tmp_blob, mem_ctx, pac_data,
 461                                          (ndr_push_flags_fn_t)ndr_push_PAC_DATA);
 462         if (!NT_STATUS_IS_OK(nt_status)) {
 463                 DEBUG(1, ("PAC (presig) push failed: %s\n", nt_errstr(nt_status)));
 464                 talloc_free(pac_data);
 465                 return EINVAL;
 466         }
 467
 468         /* Then sign the result of the previous push, where the sig was zero'ed out */
 469         ret = make_pac_checksum(mem_ctx, &tmp_blob, srv_checksum,
 470                                 context, service_keyblock);
 471
 472         /* Then sign Server checksum */
 473         ret = make_pac_checksum(mem_ctx, &srv_checksum->signature, kdc_checksum, context, krbtgt_keyblock);
 474         if (ret) {
 475                 DEBUG(2, ("making krbtgt PAC checksum failed: %s\n",
 476                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 477                 talloc_free(pac_data);
 478                 return ret;
 479         }
 480
 481         /* And push it out again, this time to the world.  This relies on determanistic pointer values */
 482         nt_status = ndr_push_struct_blob(&tmp_blob, mem_ctx, pac_data,
 483                                          (ndr_push_flags_fn_t)ndr_push_PAC_DATA);
 484         if (!NT_STATUS_IS_OK(nt_status)) {
 485                 DEBUG(1, ("PAC (final) push failed: %s\n", nt_errstr(nt_status)));
 486                 talloc_free(pac_data);
 487                 return EINVAL;
 488         }
 489
 490         *pac = tmp_blob;
 491
 492         return ret;
 493 }
 494
 495
 496  krb5_error_code kerberos_create_pac(TALLOC_CTX *mem_ctx,
 497                                      struct auth_serversupplied_info *server_info,
 498                                      krb5_context context,
 499                                      const krb5_keyblock *krbtgt_keyblock,
 500                                      const krb5_keyblock *service_keyblock,
 501                                      krb5_principal client_principal,
 502                                      time_t tgs_authtime,
 503                                      DATA_BLOB *pac)
 504 {
 505         NTSTATUS nt_status;
 506         krb5_error_code ret;
 507         struct PAC_DATA *pac_data = talloc(mem_ctx, struct PAC_DATA);
 508         struct netr_SamInfo3 *sam3;
 509         union PAC_INFO *u_LOGON_INFO;
 510         struct PAC_LOGON_INFO *LOGON_INFO;
 511         union PAC_INFO *u_LOGON_NAME;
 512         struct PAC_LOGON_NAME *LOGON_NAME;
 513         union PAC_INFO *u_KDC_CHECKSUM;
 514         union PAC_INFO *u_SRV_CHECKSUM;
 515
 516         char *name;
 517
 518         enum {
 519                 PAC_BUF_LOGON_INFO = 0,
 520                 PAC_BUF_LOGON_NAME = 1,
 521                 PAC_BUF_SRV_CHECKSUM = 2,
 522                 PAC_BUF_KDC_CHECKSUM = 3,
 523                 PAC_BUF_NUM_BUFFERS = 4
 524         };
 525
 526         if (!pac_data) {
 527                 return ENOMEM;
 528         }
 529
 530         pac_data->num_buffers = PAC_BUF_NUM_BUFFERS;
 531         pac_data->version = 0;
 532
 533         pac_data->buffers = talloc_array(pac_data,
 534                                          struct PAC_BUFFER,
 535                                          pac_data->num_buffers);
 536         if (!pac_data->buffers) {
 537                 talloc_free(pac_data);
 538                 return ENOMEM;
 539         }
 540
 541         /* LOGON_INFO */
 542         u_LOGON_INFO = talloc_zero(pac_data->buffers, union PAC_INFO);
 543         if (!u_LOGON_INFO) {
 544                 talloc_free(pac_data);
 545                 return ENOMEM;
 546         }
 547         pac_data->buffers[PAC_BUF_LOGON_INFO].type = PAC_TYPE_LOGON_INFO;
 548         pac_data->buffers[PAC_BUF_LOGON_INFO].info = u_LOGON_INFO;
 549
 550         /* LOGON_NAME */
 551         u_LOGON_NAME = talloc_zero(pac_data->buffers, union PAC_INFO);
 552         if (!u_LOGON_NAME) {
 553                 talloc_free(pac_data);
 554                 return ENOMEM;
 555         }
 556         pac_data->buffers[PAC_BUF_LOGON_NAME].type = PAC_TYPE_LOGON_NAME;
 557         pac_data->buffers[PAC_BUF_LOGON_NAME].info = u_LOGON_NAME;
 558         LOGON_NAME = &u_LOGON_NAME->logon_name;
 559
 560         /* SRV_CHECKSUM */
 561         u_SRV_CHECKSUM = talloc_zero(pac_data->buffers, union PAC_INFO);
 562         if (!u_SRV_CHECKSUM) {
 563                 talloc_free(pac_data);
 564                 return ENOMEM;
 565         }
 566         pac_data->buffers[PAC_BUF_SRV_CHECKSUM].type = PAC_TYPE_SRV_CHECKSUM;
 567         pac_data->buffers[PAC_BUF_SRV_CHECKSUM].info = u_SRV_CHECKSUM;
 568
 569         /* KDC_CHECKSUM */
 570         u_KDC_CHECKSUM = talloc_zero(pac_data->buffers, union PAC_INFO);
 571         if (!u_KDC_CHECKSUM) {
 572                 talloc_free(pac_data);
 573                 return ENOMEM;
 574         }
 575         pac_data->buffers[PAC_BUF_KDC_CHECKSUM].type = PAC_TYPE_KDC_CHECKSUM;
 576         pac_data->buffers[PAC_BUF_KDC_CHECKSUM].info = u_KDC_CHECKSUM;
 577
 578         /* now the real work begins... */
 579
 580         LOGON_INFO = talloc_zero(u_LOGON_INFO, struct PAC_LOGON_INFO);
 581         if (!LOGON_INFO) {
 582                 talloc_free(pac_data);
 583                 return ENOMEM;
 584         }
 585         nt_status = auth_convert_server_info_saminfo3(LOGON_INFO, server_info, &sam3);
 586         if (!NT_STATUS_IS_OK(nt_status)) {
 587                 DEBUG(1, ("Getting Samba info failed: %s\n", nt_errstr(nt_status)));
 588                 talloc_free(pac_data);
 589                 return EINVAL;
 590         }
 591
 592         u_LOGON_INFO->logon_info.info           = LOGON_INFO;
 593         LOGON_INFO->info3 = *sam3;
 594
 595         ret = krb5_unparse_name_flags(context, client_principal,
 596                                       KRB5_PRINCIPAL_UNPARSE_NO_REALM, &name);
 597         if (ret) {
 598                 return ret;
 599         }
 600         LOGON_NAME->account_name        = talloc_strdup(LOGON_NAME, name);
 601         free(name);
 602         /*
 603           this logon_time field is absolutely critical. This is what
 604           caused all our PAC troubles :-)
 605         */
 606         unix_to_nt_time(&LOGON_NAME->logon_time, tgs_authtime);
 607
 608         ret = kerberos_encode_pac(mem_ctx,
 609                                   pac_data,
 610                                   context,
 611                                   krbtgt_keyblock,
 612                                   service_keyblock,
 613                                   pac);
 614         talloc_free(pac_data);
 615         return ret;
 616 }
 617