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 "../lib/crypto/arcfour.h"
  29 #include "zlib.h"
  30 #include "../libcli/drsuapi/drsuapi.h"
  31 #include "libcli/auth/libcli_auth.h"
  32 #include "dsdb/samdb/samdb.h"
  33
  34 #include <gnutls/gnutls.h>
  35 #include <gnutls/crypto.h>
  36
  37 WERROR drsuapi_decrypt_attribute_value(TALLOC_CTX *mem_ctx,
  38                                        const DATA_BLOB *gensec_skey,
  39                                        bool rid_crypt,
  40                                        uint32_t rid,
  41                                        DATA_BLOB *in,
  42                                        DATA_BLOB *out)
  43 {
  44         DATA_BLOB confounder;
  45         DATA_BLOB enc_buffer;
  46
  47         gnutls_hash_hd_t hash_hnd = NULL;
  48         uint8_t _enc_key[16];
  49         DATA_BLOB enc_key;
  50
  51         DATA_BLOB dec_buffer;
  52
  53         uint32_t crc32_given;
  54         uint32_t crc32_calc;
  55         DATA_BLOB checked_buffer;
  56
  57         DATA_BLOB plain_buffer;
  58         WERROR result;
  59         int rc;
  60
  61         /*
  62          * users with rid == 0 should not exist
  63          */
  64         if (rid_crypt && rid == 0) {
  65                 return WERR_DS_DRA_INVALID_PARAMETER;
  66         }
  67
  68         /*
  69          * the first 16 bytes at the beginning are the confounder
  70          * followed by the 4 byte crc32 checksum
  71          */
  72         if (in->length < 20) {
  73                 return WERR_DS_DRA_INVALID_PARAMETER;
  74         }
  75         confounder = data_blob_const(in->data, 16);
  76         enc_buffer = data_blob_const(in->data + 16, in->length - 16);
  77
  78         /*
  79          * build the encryption key md5 over the session key followed
  80          * by the confounder
  81          *
  82          * here the gensec session key is used and
  83          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
  84          */
  85         enc_key = data_blob_const(_enc_key, sizeof(_enc_key));
  86
  87         rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
  88         if (rc < 0) {
  89                 result = WERR_NOT_ENOUGH_MEMORY;
  90                 goto out;
  91         }
  92         rc = gnutls_hash(hash_hnd, gensec_skey->data, gensec_skey->length);
  93         if (rc < 0) {
  94                 gnutls_hash_deinit(hash_hnd, NULL);
  95                 result = WERR_INTERNAL_ERROR;
  96                 goto out;
  97         }
  98         rc = gnutls_hash(hash_hnd, confounder.data, confounder.length);
  99         if (rc < 0) {
 100                 gnutls_hash_deinit(hash_hnd, NULL);
 101                 result = WERR_INTERNAL_ERROR;
 102                 goto out;
 103         }
 104
 105         gnutls_hash_deinit(hash_hnd, enc_key.data);
 106
 107         /*
 108          * copy the encrypted buffer part and
 109          * decrypt it using the created encryption key using arcfour
 110          */
 111         dec_buffer = data_blob_const(enc_buffer.data, enc_buffer.length);
 112         arcfour_crypt_blob(dec_buffer.data, dec_buffer.length, &enc_key);
 113
 114         ZERO_ARRAY_LEN(enc_key.data, enc_key.length);
 115
 116         /*
 117          * the first 4 byte are the crc32 checksum
 118          * of the remaining bytes
 119          */
 120         crc32_given = IVAL(dec_buffer.data, 0);
 121         crc32_calc = crc32(0, Z_NULL, 0);
 122         crc32_calc = crc32(crc32_calc,
 123                            dec_buffer.data + 4 ,
 124                            dec_buffer.length - 4);
 125         checked_buffer = data_blob_const(dec_buffer.data + 4, dec_buffer.length - 4);
 126
 127         plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length);
 128         W_ERROR_HAVE_NO_MEMORY(plain_buffer.data);
 129
 130         if (crc32_given != crc32_calc) {
 131                 result = W_ERROR(HRES_ERROR_V(HRES_SEC_E_DECRYPT_FAILURE));
 132                 goto out;
 133         }
 134         /*
 135          * The following rid_crypt obfuscation isn't session specific
 136          * and not really needed here, because we allways know the rid of the
 137          * user account.
 138          *
 139          * some attributes with this 'additional encryption' include
 140          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
 141          *
 142          * But for the rest of samba it's easier when we remove this static
 143          * obfuscation here
 144          */
 145         if (rid_crypt) {
 146                 uint32_t i, num_hashes;
 147
 148                 if ((checked_buffer.length % 16) != 0) {
 149                         result = WERR_DS_DRA_INVALID_PARAMETER;
 150                         goto out;
 151                 }
 152
 153                 num_hashes = plain_buffer.length / 16;
 154                 for (i = 0; i < num_hashes; i++) {
 155                         uint32_t offset = i * 16;
 156                         sam_rid_crypt(rid, checked_buffer.data + offset, plain_buffer.data + offset, 0);
 157                 }
 158         }
 159
 160         *out = plain_buffer;
 161         result = WERR_OK;
 162 out:
 163         return result;
 164 }
 165
 166 WERROR drsuapi_decrypt_attribute(TALLOC_CTX *mem_ctx,
 167                                  const DATA_BLOB *gensec_skey,
 168                                  uint32_t rid,
 169                                  uint32_t dsdb_repl_flags,
 170                                  struct drsuapi_DsReplicaAttribute *attr)
 171 {
 172         WERROR status;
 173         DATA_BLOB *enc_data;
 174         DATA_BLOB plain_data;
 175         bool rid_crypt = false;
 176
 177         if (attr->value_ctr.num_values == 0) {
 178                 return WERR_OK;
 179         }
 180
 181         switch (attr->attid) {
 182         case DRSUAPI_ATTID_dBCSPwd:
 183         case DRSUAPI_ATTID_unicodePwd:
 184         case DRSUAPI_ATTID_ntPwdHistory:
 185         case DRSUAPI_ATTID_lmPwdHistory:
 186                 rid_crypt = true;
 187                 break;
 188         case DRSUAPI_ATTID_supplementalCredentials:
 189         case DRSUAPI_ATTID_priorValue:
 190         case DRSUAPI_ATTID_currentValue:
 191         case DRSUAPI_ATTID_trustAuthOutgoing:
 192         case DRSUAPI_ATTID_trustAuthIncoming:
 193         case DRSUAPI_ATTID_initialAuthOutgoing:
 194         case DRSUAPI_ATTID_initialAuthIncoming:
 195                 break;
 196         default:
 197                 return WERR_OK;
 198         }
 199
 200         if (dsdb_repl_flags & DSDB_REPL_FLAG_EXPECT_NO_SECRETS) {
 201                 return WERR_TOO_MANY_SECRETS;
 202         }
 203
 204         if (attr->value_ctr.num_values > 1) {
 205                 return WERR_DS_DRA_INVALID_PARAMETER;
 206         }
 207
 208         if (!attr->value_ctr.values[0].blob) {
 209                 return WERR_DS_DRA_INVALID_PARAMETER;
 210         }
 211
 212         enc_data        = attr->value_ctr.values[0].blob;
 213
 214         status = drsuapi_decrypt_attribute_value(mem_ctx,
 215                                                  gensec_skey,
 216                                                  rid_crypt,
 217                                                  rid,
 218                                                  enc_data,
 219                                                  &plain_data);
 220         W_ERROR_NOT_OK_RETURN(status);
 221
 222         talloc_free(attr->value_ctr.values[0].blob->data);
 223         *attr->value_ctr.values[0].blob = plain_data;
 224
 225         return WERR_OK;
 226 }
 227
 228 static WERROR drsuapi_encrypt_attribute_value(TALLOC_CTX *mem_ctx,
 229                                               const DATA_BLOB *gensec_skey,
 230                                               bool rid_crypt,
 231                                               uint32_t rid,
 232                                               DATA_BLOB *in,
 233                                               DATA_BLOB *out)
 234 {
 235         DATA_BLOB rid_crypt_out = data_blob(NULL, 0);
 236         DATA_BLOB confounder;
 237
 238         gnutls_hash_hd_t hash_hnd = NULL;
 239         uint8_t _enc_key[16];
 240         DATA_BLOB enc_key;
 241
 242         DATA_BLOB enc_buffer;
 243
 244         uint32_t crc32_calc;
 245         WERROR result;
 246         int rc;
 247
 248         /*
 249          * users with rid == 0 should not exist
 250          */
 251         if (rid_crypt && rid == 0) {
 252                 return WERR_DS_DRA_INVALID_PARAMETER;
 253         }
 254
 255         /*
 256          * The following rid_crypt obfuscation isn't session specific
 257          * and not really needed here, because we allways know the rid of the
 258          * user account.
 259          *
 260          * some attributes with this 'additional encryption' include
 261          * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
 262          *
 263          * But for the rest of samba it's easier when we remove this static
 264          * obfuscation here
 265          */
 266         if (rid_crypt) {
 267                 uint32_t i, num_hashes;
 268                 rid_crypt_out = data_blob_talloc(mem_ctx, in->data, in->length);
 269                 W_ERROR_HAVE_NO_MEMORY(rid_crypt_out.data);
 270
 271                 if ((rid_crypt_out.length % 16) != 0) {
 272                         return WERR_DS_DRA_INVALID_PARAMETER;
 273                 }
 274
 275                 num_hashes = rid_crypt_out.length / 16;
 276                 for (i = 0; i < num_hashes; i++) {
 277                         uint32_t offset = i * 16;
 278                         sam_rid_crypt(rid, in->data + offset, rid_crypt_out.data + offset, 1);
 279                 }
 280                 in = &rid_crypt_out;
 281         }
 282
 283         /*
 284          * the first 16 bytes at the beginning are the confounder
 285          * followed by the 4 byte crc32 checksum
 286          */
 287
 288         enc_buffer = data_blob_talloc(mem_ctx, NULL, in->length+20);
 289         if (!enc_buffer.data) {
 290                 talloc_free(rid_crypt_out.data);
 291                 return WERR_NOT_ENOUGH_MEMORY;
 292         };
 293
 294         confounder = data_blob_const(enc_buffer.data, 16);
 295         generate_random_buffer(confounder.data, confounder.length);
 296
 297         /*
 298          * build the encryption key md5 over the session key followed
 299          * by the confounder
 300          *
 301          * here the gensec session key is used and
 302          * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
 303          */
 304         enc_key = data_blob_const(_enc_key, sizeof(_enc_key));
 305
 306         rc = gnutls_hash_init(&hash_hnd, GNUTLS_DIG_MD5);
 307         if (rc < 0) {
 308                 result = WERR_NOT_ENOUGH_MEMORY;
 309                 goto out;
 310         }
 311
 312         rc = gnutls_hash(hash_hnd, gensec_skey->data, gensec_skey->length);
 313         if (rc < 0) {
 314                 gnutls_hash_deinit(hash_hnd, NULL);
 315                 result = WERR_INTERNAL_ERROR;
 316                 goto out;
 317         }
 318         rc = gnutls_hash(hash_hnd, confounder.data, confounder.length);
 319         if (rc < 0) {
 320                 gnutls_hash_deinit(hash_hnd, NULL);
 321                 result = WERR_INTERNAL_ERROR;
 322                 goto out;
 323         }
 324         gnutls_hash_deinit(hash_hnd, enc_key.data);
 325
 326         /*
 327          * the first 4 byte are the crc32 checksum
 328          * of the remaining bytes
 329          */
 330         crc32_calc = crc32(0, Z_NULL, 0);
 331         crc32_calc = crc32(crc32_calc, in->data, in->length);
 332         SIVAL(enc_buffer.data, 16, crc32_calc);
 333
 334         /*
 335          * copy the plain buffer part and
 336          * encrypt it using the created encryption key using arcfour
 337          */
 338         memcpy(enc_buffer.data+20, in->data, in->length);
 339         talloc_free(rid_crypt_out.data);
 340
 341         arcfour_crypt_blob(enc_buffer.data+16, enc_buffer.length-16, &enc_key);
 342
 343         ZERO_ARRAY_LEN(enc_key.data, enc_key.length);
 344
 345         *out = enc_buffer;
 346         result =  WERR_OK;
 347 out:
 348         return result;
 349 }
 350
 351 /*
 352   encrypt a DRSUAPI attribute ready for sending over the wire
 353   Only some attribute types are encrypted
 354  */
 355 WERROR drsuapi_encrypt_attribute(TALLOC_CTX *mem_ctx,
 356                                  const DATA_BLOB *gensec_skey,
 357                                  uint32_t rid,
 358                                  struct drsuapi_DsReplicaAttribute *attr)
 359 {
 360         WERROR status;
 361         DATA_BLOB *plain_data;
 362         DATA_BLOB enc_data;
 363         bool rid_crypt = false;
 364
 365         if (attr->value_ctr.num_values == 0) {
 366                 return WERR_OK;
 367         }
 368
 369         switch (attr->attid) {
 370         case DRSUAPI_ATTID_dBCSPwd:
 371         case DRSUAPI_ATTID_unicodePwd:
 372         case DRSUAPI_ATTID_ntPwdHistory:
 373         case DRSUAPI_ATTID_lmPwdHistory:
 374                 rid_crypt = true;
 375                 break;
 376         case DRSUAPI_ATTID_supplementalCredentials:
 377         case DRSUAPI_ATTID_priorValue:
 378         case DRSUAPI_ATTID_currentValue:
 379         case DRSUAPI_ATTID_trustAuthOutgoing:
 380         case DRSUAPI_ATTID_trustAuthIncoming:
 381         case DRSUAPI_ATTID_initialAuthOutgoing:
 382         case DRSUAPI_ATTID_initialAuthIncoming:
 383                 break;
 384         default:
 385                 return WERR_OK;
 386         }
 387
 388         if (attr->value_ctr.num_values > 1) {
 389                 return WERR_DS_DRA_INVALID_PARAMETER;
 390         }
 391
 392         if (!attr->value_ctr.values[0].blob) {
 393                 return WERR_DS_DRA_INVALID_PARAMETER;
 394         }
 395
 396         plain_data      = attr->value_ctr.values[0].blob;
 397
 398         status = drsuapi_encrypt_attribute_value(mem_ctx,
 399                                                  gensec_skey,
 400                                                  rid_crypt,
 401                                                  rid,
 402                                                  plain_data,
 403                                                  &enc_data);
 404         W_ERROR_NOT_OK_RETURN(status);
 405
 406         talloc_free(attr->value_ctr.values[0].blob->data);
 407         *attr->value_ctr.values[0].blob = enc_data;
 408
 409         return WERR_OK;
 410 }
 411