libcli/drsuapi/repl_decrypt.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Helper functions for applying replicated objects
   4
   5    Copyright (C) Stefan Metzmacher <metze@samba.org> 2007
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2009
   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 3 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    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20
  21 */
  22
  23 #include "includes.h"
  24 #include "../lib/util/dlinklist.h"
  25 #include "librpc/gen_ndr/ndr_misc.h"
  26 #include "librpc/gen_ndr/ndr_drsuapi.h"
  27 #include "librpc/gen_ndr/ndr_drsblobs.h"
  28 #include "zlib.h"
  29 #include "../libcli/drsuapi/drsuapi.h"
  30 #include "libcli/auth/libcli_auth.h"
  31 #include "dsdb/samdb/samdb.h"
  32
  33 #include "lib/crypto/gnutls_helpers.h"
  34 #include <gnutls/gnutls.h>
  35 #include <gnutls/crypto.h>
  36
  37 static WERROR drsuapi_decrypt_attribute_value(TALLOC_CTX *mem_ctx,
  38                                               const DATA_BLOB *gensec_skey,
  39                                               bool rid_crypt,
  40                                               uint32_t rid,
  41                                               const DATA_BLOB *in,
  42                                               DATA_BLOB *out)
  43 {
  44         DATA_BLOB confounder;
  45         DATA_BLOB enc_buffer;
  46
  47         DATA_BLOB dec_buffer;
  48
  49         uint32_t crc32_given;
  50         uint32_t crc32_calc;
  51         DATA_BLOB checked_buffer;
  52
  53         DATA_BLOB plain_buffer;
  54         WERROR result;
  55         int rc;
  56
  57         /*
  58          * users with rid == 0 should not exist
  59          */
  60         if (rid_crypt && rid == 0) {
  61                 return WERR_DS_DRA_INVALID_PARAMETER;
  62         }
  63
  64         /*
  65          * the first 16 bytes at the beginning are the confounder
  66          * followed by the 4 byte crc32 checksum
  67          */
  68         if (in->length < 20) {
  69                 return WERR_DS_DRA_INVALID_PARAMETER;
  70         }
  71         confounder = data_blob_const(in->data, 16);
  72         enc_buffer = data_blob_const(in->data + 16, in->length - 16);
  73
  74         /*
  75          * decrypt with the encryption key, being md5 over the session
  76          * key followed by the confounder.  The parameter order to
  77          * samba_gnutls_arcfour_confounded_md5() matters for this!
  78          *
  79          * here the gensec session key is used and
  80          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
  81          */
  82
  83         /*
  84          * reference the encrypted buffer part and
  85          * decrypt it using the created encryption key using arcfour
  86          */
  87         dec_buffer = data_blob_const(enc_buffer.data, enc_buffer.length);
  88
  89         rc = samba_gnutls_arcfour_confounded_md5(gensec_skey,
  90                                                  &confounder,
  91                                                  &dec_buffer,
  92                                                  SAMBA_GNUTLS_DECRYPT);
  93         if (rc < 0) {
  94                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
  95                 goto out;
  96         }
  97
  98         /*
  99          * the first 4 byte are the crc32 checksum
 100          * of the remaining bytes
 101          */
 102         crc32_given = IVAL(dec_buffer.data, 0);
 103         crc32_calc = crc32(0, Z_NULL, 0);
 104         crc32_calc = crc32(crc32_calc,
 105                            dec_buffer.data + 4 ,
 106                            dec_buffer.length - 4);
 107         checked_buffer = data_blob_const(dec_buffer.data + 4, dec_buffer.length - 4);
 108
 109         plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length);
 110         W_ERROR_HAVE_NO_MEMORY(plain_buffer.data);
 111
 112         if (crc32_given != crc32_calc) {
 113                 result = W_ERROR(HRES_ERROR_V(HRES_SEC_E_DECRYPT_FAILURE));
 114                 goto out;
 115         }
 116         /*
 117          * The following rid_crypt obfuscation isn't session specific
 118          * and not really needed here, because we always know the rid of the
 119          * user account.
 120          *
 121          * some attributes with this 'additional encryption' include
 122          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
 123          *
 124          * But for the rest of samba it's easier when we remove this static
 125          * obfuscation here
 126          */
 127         if (rid_crypt) {
 128                 uint32_t i, num_hashes;
 129
 130                 if ((checked_buffer.length % 16) != 0) {
 131                         result = WERR_DS_DRA_INVALID_PARAMETER;
 132                         goto out;
 133                 }
 134
 135                 num_hashes = plain_buffer.length / 16;
 136                 for (i = 0; i < num_hashes; i++) {
 137                         uint32_t offset = i * 16;
 138                         rc = sam_rid_crypt(rid, checked_buffer.data + offset,
 139                                            plain_buffer.data + offset,
 140                                            SAMBA_GNUTLS_DECRYPT);
 141                         if (rc != 0) {
 142                                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
 143                                 goto out;
 144                         }
 145                 }
 146         }
 147
 148         *out = plain_buffer;
 149         result = WERR_OK;
 150 out:
 151         return result;
 152 }
 153
 154 WERROR drsuapi_decrypt_attribute(TALLOC_CTX *mem_ctx,
 155                                  const DATA_BLOB *gensec_skey,
 156                                  uint32_t rid,
 157                                  uint32_t dsdb_repl_flags,
 158                                  struct drsuapi_DsReplicaAttribute *attr)
 159 {
 160         WERROR status;
 161         DATA_BLOB *enc_data;
 162         DATA_BLOB plain_data;
 163         bool rid_crypt = false;
 164
 165         if (attr->value_ctr.num_values == 0) {
 166                 return WERR_OK;
 167         }
 168
 169         switch (attr->attid) {
 170         case DRSUAPI_ATTID_dBCSPwd:
 171         case DRSUAPI_ATTID_unicodePwd:
 172         case DRSUAPI_ATTID_ntPwdHistory:
 173         case DRSUAPI_ATTID_lmPwdHistory:
 174                 rid_crypt = true;
 175                 break;
 176         case DRSUAPI_ATTID_supplementalCredentials:
 177         case DRSUAPI_ATTID_priorValue:
 178         case DRSUAPI_ATTID_currentValue:
 179         case DRSUAPI_ATTID_trustAuthOutgoing:
 180         case DRSUAPI_ATTID_trustAuthIncoming:
 181         case DRSUAPI_ATTID_initialAuthOutgoing:
 182         case DRSUAPI_ATTID_initialAuthIncoming:
 183                 break;
 184         default:
 185                 return WERR_OK;
 186         }
 187
 188         if (dsdb_repl_flags & DSDB_REPL_FLAG_EXPECT_NO_SECRETS) {
 189                 return WERR_TOO_MANY_SECRETS;
 190         }
 191
 192         if (attr->value_ctr.num_values > 1) {
 193                 return WERR_DS_DRA_INVALID_PARAMETER;
 194         }
 195
 196         if (!attr->value_ctr.values[0].blob) {
 197                 return WERR_DS_DRA_INVALID_PARAMETER;
 198         }
 199
 200         enc_data        = attr->value_ctr.values[0].blob;
 201
 202         status = drsuapi_decrypt_attribute_value(mem_ctx,
 203                                                  gensec_skey,
 204                                                  rid_crypt,
 205                                                  rid,
 206                                                  enc_data,
 207                                                  &plain_data);
 208         W_ERROR_NOT_OK_RETURN(status);
 209
 210         talloc_free(attr->value_ctr.values[0].blob->data);
 211         *attr->value_ctr.values[0].blob = plain_data;
 212
 213         return WERR_OK;
 214 }
 215
 216 static WERROR drsuapi_encrypt_attribute_value(TALLOC_CTX *mem_ctx,
 217                                               const DATA_BLOB *gensec_skey,
 218                                               bool rid_crypt,
 219                                               uint32_t rid,
 220                                               const DATA_BLOB *in,
 221                                               DATA_BLOB *out)
 222 {
 223         DATA_BLOB rid_crypt_out = data_blob(NULL, 0);
 224         DATA_BLOB confounder;
 225
 226         DATA_BLOB enc_buffer;
 227
 228         DATA_BLOB to_encrypt;
 229
 230         uint32_t crc32_calc;
 231         WERROR result;
 232         int rc;
 233
 234         /*
 235          * users with rid == 0 should not exist
 236          */
 237         if (rid_crypt && rid == 0) {
 238                 return WERR_DS_DRA_INVALID_PARAMETER;
 239         }
 240
 241         /*
 242          * The following rid_crypt obfuscation isn't session specific
 243          * and not really needed here, because we always know the rid of the
 244          * user account.
 245          *
 246          * some attributes with this 'additional encryption' include
 247          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
 248          *
 249          * But for the rest of samba it's easier when we remove this static
 250          * obfuscation here
 251          */
 252         if (rid_crypt) {
 253                 uint32_t i, num_hashes;
 254                 rid_crypt_out = data_blob_talloc(mem_ctx, in->data, in->length);
 255                 W_ERROR_HAVE_NO_MEMORY(rid_crypt_out.data);
 256
 257                 if ((rid_crypt_out.length % 16) != 0) {
 258                         return WERR_DS_DRA_INVALID_PARAMETER;
 259                 }
 260
 261                 num_hashes = rid_crypt_out.length / 16;
 262                 for (i = 0; i < num_hashes; i++) {
 263                         uint32_t offset = i * 16;
 264                         rc = sam_rid_crypt(rid, in->data + offset,
 265                                            rid_crypt_out.data + offset,
 266                                            SAMBA_GNUTLS_ENCRYPT);
 267                         if (rc != 0) {
 268                                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
 269                                 goto out;
 270                         }
 271                 }
 272                 in = &rid_crypt_out;
 273         }
 274
 275         /*
 276          * the first 16 bytes at the beginning are the confounder
 277          * followed by the 4 byte crc32 checksum
 278          */
 279
 280         enc_buffer = data_blob_talloc(mem_ctx, NULL, in->length+20);
 281         if (!enc_buffer.data) {
 282                 talloc_free(rid_crypt_out.data);
 283                 return WERR_NOT_ENOUGH_MEMORY;
 284         };
 285
 286         confounder = data_blob_const(enc_buffer.data, 16);
 287         generate_random_buffer(confounder.data, confounder.length);
 288
 289         /*
 290          * the first 4 byte are the crc32 checksum
 291          * of the remaining bytes
 292          */
 293         crc32_calc = crc32(0, Z_NULL, 0);
 294         crc32_calc = crc32(crc32_calc, in->data, in->length);
 295         SIVAL(enc_buffer.data, 16, crc32_calc);
 296
 297         /*
 298          * copy the plain buffer part and
 299          * encrypt it using the created encryption key using arcfour
 300          */
 301         memcpy(enc_buffer.data+20, in->data, in->length);
 302         talloc_free(rid_crypt_out.data);
 303
 304         to_encrypt = data_blob_const(enc_buffer.data+16,
 305                                      enc_buffer.length-16);
 306
 307         /*
 308          * encrypt with the encryption key, being md5 over the session
 309          * key followed by the confounder.  The parameter order to
 310          * samba_gnutls_arcfour_confounded_md5() matters for this!
 311          *
 312          * here the gensec session key is used and
 313          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
 314          */
 315
 316         rc = samba_gnutls_arcfour_confounded_md5(gensec_skey,
 317                                                  &confounder,
 318                                                  &to_encrypt,
 319                                                  SAMBA_GNUTLS_ENCRYPT);
 320         if (rc < 0) {
 321                 result = gnutls_error_to_werror(rc, WERR_INTERNAL_ERROR);
 322                 goto out;
 323         }
 324
 325         *out = enc_buffer;
 326         result =  WERR_OK;
 327 out:
 328         return result;
 329 }
 330
 331 /*
 332   encrypt a DRSUAPI attribute ready for sending over the wire
 333   Only some attribute types are encrypted
 334  */
 335 WERROR drsuapi_encrypt_attribute(TALLOC_CTX *mem_ctx,
 336                                  const DATA_BLOB *gensec_skey,
 337                                  uint32_t rid,
 338                                  struct drsuapi_DsReplicaAttribute *attr)
 339 {
 340         WERROR status;
 341         DATA_BLOB *plain_data;
 342         DATA_BLOB enc_data;
 343         bool rid_crypt = false;
 344
 345         if (attr->value_ctr.num_values == 0) {
 346                 return WERR_OK;
 347         }
 348
 349         switch (attr->attid) {
 350         case DRSUAPI_ATTID_dBCSPwd:
 351         case DRSUAPI_ATTID_unicodePwd:
 352         case DRSUAPI_ATTID_ntPwdHistory:
 353         case DRSUAPI_ATTID_lmPwdHistory:
 354                 rid_crypt = true;
 355                 break;
 356         case DRSUAPI_ATTID_supplementalCredentials:
 357         case DRSUAPI_ATTID_priorValue:
 358         case DRSUAPI_ATTID_currentValue:
 359         case DRSUAPI_ATTID_trustAuthOutgoing:
 360         case DRSUAPI_ATTID_trustAuthIncoming:
 361         case DRSUAPI_ATTID_initialAuthOutgoing:
 362         case DRSUAPI_ATTID_initialAuthIncoming:
 363                 break;
 364         default:
 365                 return WERR_OK;
 366         }
 367
 368         if (attr->value_ctr.num_values > 1) {
 369                 return WERR_DS_DRA_INVALID_PARAMETER;
 370         }
 371
 372         if (!attr->value_ctr.values[0].blob) {
 373                 return WERR_DS_DRA_INVALID_PARAMETER;
 374         }
 375
 376         plain_data      = attr->value_ctr.values[0].blob;
 377
 378         status = drsuapi_encrypt_attribute_value(mem_ctx,
 379                                                  gensec_skey,
 380                                                  rid_crypt,
 381                                                  rid,
 382                                                  plain_data,
 383                                                  &enc_data);
 384         W_ERROR_NOT_OK_RETURN(status);
 385
 386         talloc_free(attr->value_ctr.values[0].blob->data);
 387         *attr->value_ctr.values[0].blob = enc_data;
 388
 389         return WERR_OK;
 390 }
 391