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 "libcli/auth/krb5_wrap.h"
  30
  31 krb5_error_code check_pac_checksum(TALLOC_CTX *mem_ctx,
  32                                           DATA_BLOB pac_data,
  33                                           struct PAC_SIGNATURE_DATA *sig,
  34                                           krb5_context context,
  35                                           const krb5_keyblock *keyblock)
  36 {
  37         krb5_error_code ret;
  38         krb5_checksum cksum;
  39         krb5_keyusage usage = 0;
  40
  41         smb_krb5_checksum_from_pac_sig(&cksum, sig);
  42
  43 #ifdef HAVE_KRB5_KU_OTHER_CKSUM /* Heimdal */
  44         usage = KRB5_KU_OTHER_CKSUM;
  45 #elif defined(HAVE_KRB5_KEYUSAGE_APP_DATA_CKSUM) /* MIT */
  46         usage = KRB5_KEYUSAGE_APP_DATA_CKSUM;
  47 #else
  48 #error UNKNOWN_KRB5_KEYUSAGE
  49 #endif
  50
  51         ret = smb_krb5_verify_checksum(context,
  52                                        keyblock,
  53                                        usage,
  54                                        &cksum,
  55                                        pac_data.data,
  56                                        pac_data.length);
  57
  58         if (ret) {
  59                 DEBUG(2,("check_pac_checksum: PAC Verification failed: %s (%d)\n",
  60                         error_message(ret), ret));
  61                 return ret;
  62         }
  63
  64         return ret;
  65 }
  66
  67 /**
  68 * @brief Decode a blob containing a NDR envoded PAC structure
  69 *
  70 * @param mem_ctx          - The memory context
  71 * @param pac_data_blob    - The data blob containing the NDR encoded data
  72 * @param context          - The Kerberos Context
  73 * @param service_keyblock - The Service Key used to verify the checksum
  74 * @param client_principal - The client principal
  75 * @param tgs_authtime     - The ticket timestamp
  76 * @param pac_data_out     - [out] The decoded PAC
  77 *
  78 * @return - A NTSTATUS error code
  79 */
  80 NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
  81                              DATA_BLOB pac_data_blob,
  82                              krb5_context context,
  83                              const krb5_keyblock *krbtgt_keyblock,
  84                              const krb5_keyblock *service_keyblock,
  85                              krb5_const_principal client_principal,
  86                              time_t tgs_authtime,
  87                              struct PAC_DATA **pac_data_out)
  88 {
  89         NTSTATUS status;
  90         enum ndr_err_code ndr_err;
  91         krb5_error_code ret;
  92         DATA_BLOB modified_pac_blob;
  93
  94         NTTIME tgs_authtime_nttime;
  95         krb5_principal client_principal_pac = NULL;
  96         int i;
  97
  98         struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
  99         struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
 100         struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL;
 101         struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL;
 102         struct PAC_LOGON_NAME *logon_name = NULL;
 103         struct PAC_LOGON_INFO *logon_info = NULL;
 104         struct PAC_DATA *pac_data = NULL;
 105         struct PAC_DATA_RAW *pac_data_raw = NULL;
 106
 107         DATA_BLOB *srv_sig_blob = NULL;
 108         DATA_BLOB *kdc_sig_blob = NULL;
 109
 110         bool bool_ret;
 111
 112         *pac_data_out = NULL;
 113
 114         pac_data = talloc(mem_ctx, struct PAC_DATA);
 115         pac_data_raw = talloc(mem_ctx, struct PAC_DATA_RAW);
 116         kdc_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
 117         srv_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
 118         if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) {
 119                 return NT_STATUS_NO_MEMORY;
 120         }
 121
 122         ndr_err = ndr_pull_struct_blob(&pac_data_blob, pac_data, pac_data,
 123                        (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
 124         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 125                 status = ndr_map_error2ntstatus(ndr_err);
 126                 DEBUG(0,("can't parse the PAC: %s\n",
 127                         nt_errstr(status)));
 128                 return status;
 129         }
 130
 131         if (pac_data->num_buffers < 4) {
 132                 /* we need logon_ingo, service_key and kdc_key */
 133                 DEBUG(0,("less than 4 PAC buffers\n"));
 134                 return NT_STATUS_INVALID_PARAMETER;
 135         }
 136
 137         ndr_err = ndr_pull_struct_blob(
 138                                 &pac_data_blob, pac_data_raw, pac_data_raw,
 139                                 (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW);
 140         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 141                 status = ndr_map_error2ntstatus(ndr_err);
 142                 DEBUG(0,("can't parse the PAC: %s\n",
 143                         nt_errstr(status)));
 144                 return status;
 145         }
 146
 147         if (pac_data_raw->num_buffers < 4) {
 148                 /* we need logon_ingo, service_key and kdc_key */
 149                 DEBUG(0,("less than 4 PAC buffers\n"));
 150                 return NT_STATUS_INVALID_PARAMETER;
 151         }
 152
 153         if (pac_data->num_buffers != pac_data_raw->num_buffers) {
 154                 /* we need logon_ingo, service_key and kdc_key */
 155                 DEBUG(0, ("misparse! PAC_DATA has %d buffers while "
 156                           "PAC_DATA_RAW has %d\n", pac_data->num_buffers,
 157                           pac_data_raw->num_buffers));
 158                 return NT_STATUS_INVALID_PARAMETER;
 159         }
 160
 161         for (i=0; i < pac_data->num_buffers; i++) {
 162                 struct PAC_BUFFER *data_buf = &pac_data->buffers[i];
 163                 struct PAC_BUFFER_RAW *raw_buf = &pac_data_raw->buffers[i];
 164
 165                 if (data_buf->type != raw_buf->type) {
 166                         DEBUG(0, ("misparse! PAC_DATA buffer %d has type "
 167                                   "%d while PAC_DATA_RAW has %d\n", i,
 168                                   data_buf->type, raw_buf->type));
 169                         return NT_STATUS_INVALID_PARAMETER;
 170                 }
 171                 switch (data_buf->type) {
 172                 case PAC_TYPE_LOGON_INFO:
 173                         if (!data_buf->info) {
 174                                 break;
 175                         }
 176                         logon_info = data_buf->info->logon_info.info;
 177                         break;
 178                 case PAC_TYPE_SRV_CHECKSUM:
 179                         if (!data_buf->info) {
 180                                 break;
 181                         }
 182                         srv_sig_ptr = &data_buf->info->srv_cksum;
 183                         srv_sig_blob = &raw_buf->info->remaining;
 184                         break;
 185                 case PAC_TYPE_KDC_CHECKSUM:
 186                         if (!data_buf->info) {
 187                                 break;
 188                         }
 189                         kdc_sig_ptr = &data_buf->info->kdc_cksum;
 190                         kdc_sig_blob = &raw_buf->info->remaining;
 191                         break;
 192                 case PAC_TYPE_LOGON_NAME:
 193                         logon_name = &data_buf->info->logon_name;
 194                         break;
 195                 default:
 196                         break;
 197                 }
 198         }
 199
 200         if (!logon_info) {
 201                 DEBUG(0,("PAC no logon_info\n"));
 202                 return NT_STATUS_INVALID_PARAMETER;
 203         }
 204
 205         if (!logon_name) {
 206                 DEBUG(0,("PAC no logon_name\n"));
 207                 return NT_STATUS_INVALID_PARAMETER;
 208         }
 209
 210         if (!srv_sig_ptr || !srv_sig_blob) {
 211                 DEBUG(0,("PAC no srv_key\n"));
 212                 return NT_STATUS_INVALID_PARAMETER;
 213         }
 214
 215         if (!kdc_sig_ptr || !kdc_sig_blob) {
 216                 DEBUG(0,("PAC no kdc_key\n"));
 217                 return NT_STATUS_INVALID_PARAMETER;
 218         }
 219
 220         /* Find and zero out the signatures,
 221          * as required by the signing algorithm */
 222
 223         /* We find the data blobs above,
 224          * now we parse them to get at the exact portion we should zero */
 225         ndr_err = ndr_pull_struct_blob(
 226                         kdc_sig_blob, kdc_sig_wipe, kdc_sig_wipe,
 227                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 228         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 229                 status = ndr_map_error2ntstatus(ndr_err);
 230                 DEBUG(0,("can't parse the KDC signature: %s\n",
 231                         nt_errstr(status)));
 232                 return status;
 233         }
 234
 235         ndr_err = ndr_pull_struct_blob(
 236                         srv_sig_blob, srv_sig_wipe, srv_sig_wipe,
 237                         (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
 238         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 239                 status = ndr_map_error2ntstatus(ndr_err);
 240                 DEBUG(0,("can't parse the SRV signature: %s\n",
 241                         nt_errstr(status)));
 242                 return status;
 243         }
 244
 245         /* Now zero the decoded structure */
 246         memset(kdc_sig_wipe->signature.data,
 247                 '\0', kdc_sig_wipe->signature.length);
 248         memset(srv_sig_wipe->signature.data,
 249                 '\0', srv_sig_wipe->signature.length);
 250
 251         /* and reencode, back into the same place it came from */
 252         ndr_err = ndr_push_struct_blob(
 253                         kdc_sig_blob, pac_data_raw, kdc_sig_wipe,
 254                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 255         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 256                 status = ndr_map_error2ntstatus(ndr_err);
 257                 DEBUG(0,("can't repack the KDC signature: %s\n",
 258                         nt_errstr(status)));
 259                 return status;
 260         }
 261         ndr_err = ndr_push_struct_blob(
 262                         srv_sig_blob, pac_data_raw, srv_sig_wipe,
 263                         (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
 264         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 265                 status = ndr_map_error2ntstatus(ndr_err);
 266                 DEBUG(0,("can't repack the SRV signature: %s\n",
 267                         nt_errstr(status)));
 268                 return status;
 269         }
 270
 271         /* push out the whole structure, but now with zero'ed signatures */
 272         ndr_err = ndr_push_struct_blob(
 273                         &modified_pac_blob, pac_data_raw, pac_data_raw,
 274                         (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW);
 275         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 276                 status = ndr_map_error2ntstatus(ndr_err);
 277                 DEBUG(0,("can't repack the RAW PAC: %s\n",
 278                         nt_errstr(status)));
 279                 return status;
 280         }
 281
 282         if (service_keyblock) {
 283                 /* verify by service_key */
 284                 ret = check_pac_checksum(mem_ctx,
 285                                          modified_pac_blob, srv_sig_ptr,
 286                                          context,
 287                                          service_keyblock);
 288                 if (ret) {
 289                         DEBUG(1, ("PAC Decode: Failed to verify the service "
 290                                   "signature: %s\n", error_message(ret)));
 291                         return NT_STATUS_ACCESS_DENIED;
 292                 }
 293
 294                 if (krbtgt_keyblock) {
 295                         /* verify the service key checksum by krbtgt_key */
 296                         ret = check_pac_checksum(mem_ctx,
 297                                                  srv_sig_ptr->signature, kdc_sig_ptr,
 298                                                  context, krbtgt_keyblock);
 299                         if (ret) {
 300                                 DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
 301                                           smb_get_krb5_error_message(context, ret, mem_ctx)));
 302                                 return NT_STATUS_ACCESS_DENIED;
 303                         }
 304                 }
 305         }
 306
 307         if (tgs_authtime) {
 308                 /* Convert to NT time, so as not to loose accuracy in comparison */
 309                 unix_to_nt_time(&tgs_authtime_nttime, tgs_authtime);
 310
 311                 if (tgs_authtime_nttime != logon_name->logon_time) {
 312                         DEBUG(2, ("PAC Decode: "
 313                                   "Logon time mismatch between ticket and PAC!\n"));
 314                         DEBUG(2, ("PAC Decode: PAC: %s\n",
 315                                   nt_time_string(mem_ctx, logon_name->logon_time)));
 316                         DEBUG(2, ("PAC Decode: Ticket: %s\n",
 317                                   nt_time_string(mem_ctx, tgs_authtime_nttime)));
 318                         return NT_STATUS_ACCESS_DENIED;
 319                 }
 320         }
 321
 322         if (client_principal) {
 323                 ret = smb_krb5_parse_name_norealm(context,
 324                                                   logon_name->account_name,
 325                                                   &client_principal_pac);
 326                 if (ret) {
 327                         DEBUG(2, ("Could not parse name from PAC: [%s]:%s\n",
 328                                   logon_name->account_name, error_message(ret)));
 329                         return NT_STATUS_INVALID_PARAMETER;
 330                 }
 331
 332                 bool_ret = smb_krb5_principal_compare_any_realm(context,
 333                                                                 client_principal,
 334                                                                 client_principal_pac);
 335
 336                 krb5_free_principal(context, client_principal_pac);
 337
 338                 if (!bool_ret) {
 339                         DEBUG(2, ("Name in PAC [%s] does not match principal name "
 340                                   "in ticket\n", logon_name->account_name));
 341                         return NT_STATUS_ACCESS_DENIED;
 342                 }
 343         }
 344
 345         DEBUG(3,("Found account name from PAC: %s [%s]\n",
 346                  logon_info->info3.base.account_name.string,
 347                  logon_info->info3.base.full_name.string));
 348
 349         DEBUG(10,("Successfully validated Kerberos PAC\n"));
 350
 351         if (DEBUGLEVEL >= 10) {
 352                 const char *s;
 353                 s = NDR_PRINT_STRUCT_STRING(mem_ctx, PAC_DATA, pac_data);
 354                 if (s) {
 355                         DEBUGADD(10,("%s\n", s));
 356                 }
 357         }
 358
 359         *pac_data_out = pac_data;
 360
 361         return NT_STATUS_OK;
 362 }
 363
 364 #endif