source3/libsmb/ntlmssp_sign.c

   1 /*
   2  *  Unix SMB/CIFS implementation.
   3  *  Version 3.0
   4  *  NTLMSSP Signing routines
   5  *  Copyright (C) Andrew Bartlett 2003-2005
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 3 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include "includes.h"
  22 #include "ntlmssp.h"
  23 #include "../libcli/auth/libcli_auth.h"
  24
  25 #define CLI_SIGN "session key to client-to-server signing key magic constant"
  26 #define CLI_SEAL "session key to client-to-server sealing key magic constant"
  27 #define SRV_SIGN "session key to server-to-client signing key magic constant"
  28 #define SRV_SEAL "session key to server-to-client sealing key magic constant"
  29
  30 /**
  31  * Some notes on then NTLM2 code:
  32  *
  33  * NTLM2 is a AEAD system.  This means that the data encrypted is not
  34  * all the data that is signed.  In DCE-RPC case, the headers of the
  35  * DCE-RPC packets are also signed.  This prevents some of the
  36  * fun-and-games one might have by changing them.
  37  *
  38  */
  39
  40 static void dump_arc4_state(const char *description,
  41                             struct arcfour_state *state)
  42 {
  43         dump_data_pw(description, state->sbox, sizeof(state->sbox));
  44 }
  45
  46 static void calc_ntlmv2_key(unsigned char subkey[16],
  47                                 DATA_BLOB session_key,
  48                                 const char *constant)
  49 {
  50         struct MD5Context ctx3;
  51         MD5Init(&ctx3);
  52         MD5Update(&ctx3, session_key.data, session_key.length);
  53         MD5Update(&ctx3, (const unsigned char *)constant, strlen(constant)+1);
  54         MD5Final(subkey, &ctx3);
  55 }
  56
  57 enum ntlmssp_direction {
  58         NTLMSSP_SEND,
  59         NTLMSSP_RECEIVE
  60 };
  61
  62 static NTSTATUS ntlmssp_make_packet_signature(struct ntlmssp_state *ntlmssp_state,
  63                                                 const uchar *data, size_t length,
  64                                                 const uchar *whole_pdu, size_t pdu_length,
  65                                                 enum ntlmssp_direction direction,
  66                                                 DATA_BLOB *sig,
  67                                                 bool encrypt_sig)
  68 {
  69         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
  70                 HMACMD5Context ctx;
  71                 uchar seq_num[4];
  72                 uchar digest[16];
  73
  74                 *sig = data_blob(NULL, NTLMSSP_SIG_SIZE);
  75                 if (!sig->data) {
  76                         return NT_STATUS_NO_MEMORY;
  77                 }
  78
  79                 switch (direction) {
  80                 case NTLMSSP_SEND:
  81                         DEBUG(100,("ntlmssp_make_packet_signature: SEND seq = %u, len = %u, pdu_len = %u\n",
  82                                 ntlmssp_state->ntlm2_send_seq_num,
  83                                 (unsigned int)length,
  84                                 (unsigned int)pdu_length));
  85
  86                         SIVAL(seq_num, 0, ntlmssp_state->ntlm2_send_seq_num);
  87                         ntlmssp_state->ntlm2_send_seq_num++;
  88                         hmac_md5_init_limK_to_64(ntlmssp_state->send_sign_key, 16, &ctx);
  89                         break;
  90                 case NTLMSSP_RECEIVE:
  91
  92                         DEBUG(100,("ntlmssp_make_packet_signature: RECV seq = %u, len = %u, pdu_len = %u\n",
  93                                 ntlmssp_state->ntlm2_recv_seq_num,
  94                                 (unsigned int)length,
  95                                 (unsigned int)pdu_length));
  96
  97                         SIVAL(seq_num, 0, ntlmssp_state->ntlm2_recv_seq_num);
  98                         ntlmssp_state->ntlm2_recv_seq_num++;
  99                         hmac_md5_init_limK_to_64(ntlmssp_state->recv_sign_key, 16, &ctx);
 100                         break;
 101                 }
 102
 103                 dump_data_pw("pdu data ", whole_pdu, pdu_length);
 104
 105                 hmac_md5_update(seq_num, 4, &ctx);
 106                 hmac_md5_update(whole_pdu, pdu_length, &ctx);
 107                 hmac_md5_final(digest, &ctx);
 108
 109                 if (encrypt_sig && (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH)) {
 110                         switch (direction) {
 111                         case NTLMSSP_SEND:
 112                                 arcfour_crypt_sbox(&ntlmssp_state->send_seal_arc4_state, digest, 8);
 113                                 break;
 114                         case NTLMSSP_RECEIVE:
 115                                 arcfour_crypt_sbox(&ntlmssp_state->recv_seal_arc4_state, digest, 8);
 116                                 break;
 117                         }
 118                 }
 119
 120                 SIVAL(sig->data, 0, NTLMSSP_SIGN_VERSION);
 121                 memcpy(sig->data + 4, digest, 8);
 122                 memcpy(sig->data + 12, seq_num, 4);
 123
 124                 dump_data_pw("ntlmssp v2 sig ", sig->data, sig->length);
 125
 126         } else {
 127                 uint32 crc;
 128                 crc = crc32_calc_buffer(data, length);
 129                 if (!msrpc_gen(ntlmssp_state, sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 130                         return NT_STATUS_NO_MEMORY;
 131                 }
 132
 133                 ntlmssp_state->ntlmv1_seq_num++;
 134
 135                 dump_arc4_state("ntlmssp hash: \n", &ntlmssp_state->ntlmv1_arc4_state);
 136                 arcfour_crypt_sbox(&ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 137         }
 138         return NT_STATUS_OK;
 139 }
 140
 141 NTSTATUS ntlmssp_sign_packet(struct ntlmssp_state *ntlmssp_state,
 142                                     const uchar *data, size_t length,
 143                                     const uchar *whole_pdu, size_t pdu_length,
 144                                     DATA_BLOB *sig)
 145 {
 146         NTSTATUS nt_status;
 147
 148         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN)) {
 149                 DEBUG(3, ("NTLMSSP Signing not negotiated - cannot sign packet!\n"));
 150                 return NT_STATUS_INVALID_PARAMETER;
 151         }
 152
 153         if (!ntlmssp_state->session_key.length) {
 154                 DEBUG(3, ("NO session key, cannot check sign packet\n"));
 155                 return NT_STATUS_NO_USER_SESSION_KEY;
 156         }
 157
 158         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 159                                                 data, length,
 160                                                 whole_pdu, pdu_length,
 161                                                 NTLMSSP_SEND, sig, True);
 162
 163         return nt_status;
 164 }
 165
 166 /**
 167  * Check the signature of an incoming packet
 168  * @note caller *must* check that the signature is the size it expects
 169  *
 170  */
 171
 172 NTSTATUS ntlmssp_check_packet(struct ntlmssp_state *ntlmssp_state,
 173                                 const uchar *data, size_t length,
 174                                 const uchar *whole_pdu, size_t pdu_length,
 175                                 const DATA_BLOB *sig)
 176 {
 177         DATA_BLOB local_sig;
 178         NTSTATUS nt_status;
 179
 180         if (!ntlmssp_state->session_key.length) {
 181                 DEBUG(3, ("NO session key, cannot check packet signature\n"));
 182                 return NT_STATUS_NO_USER_SESSION_KEY;
 183         }
 184
 185         if (sig->length < 8) {
 186                 DEBUG(0, ("NTLMSSP packet check failed due to short signature (%lu bytes)!\n",
 187                           (unsigned long)sig->length));
 188         }
 189
 190         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 191                                                 data, length,
 192                                                 whole_pdu, pdu_length,
 193                                                 NTLMSSP_RECEIVE, &local_sig, True);
 194
 195         if (!NT_STATUS_IS_OK(nt_status)) {
 196                 DEBUG(0, ("NTLMSSP packet check failed with %s\n", nt_errstr(nt_status)));
 197                 data_blob_free(&local_sig);
 198                 return nt_status;
 199         }
 200
 201         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 202                 if (local_sig.length != sig->length ||
 203                                 memcmp(local_sig.data, sig->data, sig->length) != 0) {
 204                         DEBUG(5, ("BAD SIG NTLM2: wanted signature of\n"));
 205                         dump_data(5, local_sig.data, local_sig.length);
 206
 207                         DEBUG(5, ("BAD SIG: got signature of\n"));
 208                         dump_data(5, sig->data, sig->length);
 209
 210                         DEBUG(0, ("NTLMSSP NTLM2 packet check failed due to invalid signature!\n"));
 211                         data_blob_free(&local_sig);
 212                         return NT_STATUS_ACCESS_DENIED;
 213                 }
 214         } else {
 215                 if (local_sig.length != sig->length ||
 216                                 memcmp(local_sig.data + 8, sig->data + 8, sig->length - 8) != 0) {
 217                         DEBUG(5, ("BAD SIG NTLM1: wanted signature of\n"));
 218                         dump_data(5, local_sig.data, local_sig.length);
 219
 220                         DEBUG(5, ("BAD SIG: got signature of\n"));
 221                         dump_data(5, sig->data, sig->length);
 222
 223                         DEBUG(0, ("NTLMSSP NTLM1 packet check failed due to invalid signature!\n"));
 224                         data_blob_free(&local_sig);
 225                         return NT_STATUS_ACCESS_DENIED;
 226                 }
 227         }
 228         dump_data_pw("checked ntlmssp signature\n", sig->data, sig->length);
 229         DEBUG(10,("ntlmssp_check_packet: NTLMSSP signature OK !\n"));
 230
 231         data_blob_free(&local_sig);
 232         return NT_STATUS_OK;
 233 }
 234
 235 /**
 236  * Seal data with the NTLMSSP algorithm
 237  *
 238  */
 239
 240 NTSTATUS ntlmssp_seal_packet(struct ntlmssp_state *ntlmssp_state,
 241                              uchar *data, size_t length,
 242                              uchar *whole_pdu, size_t pdu_length,
 243                              DATA_BLOB *sig)
 244 {
 245         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL)) {
 246                 DEBUG(3, ("NTLMSSP Sealing not negotiated - cannot seal packet!\n"));
 247                 return NT_STATUS_INVALID_PARAMETER;
 248         }
 249
 250         if (!ntlmssp_state->session_key.length) {
 251                 DEBUG(3, ("NO session key, cannot seal packet\n"));
 252                 return NT_STATUS_NO_USER_SESSION_KEY;
 253         }
 254
 255         DEBUG(10,("ntlmssp_seal_data: seal\n"));
 256         dump_data_pw("ntlmssp clear data\n", data, length);
 257         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 258                 /* The order of these two operations matters - we must first seal the packet,
 259                    then seal the sequence number - this is because the send_seal_hash is not
 260                    constant, but is is rather updated with each iteration */
 261                 NTSTATUS nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 262                                                         data, length,
 263                                                         whole_pdu, pdu_length,
 264                                                         NTLMSSP_SEND, sig, False);
 265                 if (!NT_STATUS_IS_OK(nt_status)) {
 266                         return nt_status;
 267                 }
 268
 269                 arcfour_crypt_sbox(&ntlmssp_state->send_seal_arc4_state, data, length);
 270                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH) {
 271                         arcfour_crypt_sbox(&ntlmssp_state->send_seal_arc4_state, sig->data+4, 8);
 272                 }
 273         } else {
 274                 uint32 crc;
 275                 crc = crc32_calc_buffer(data, length);
 276                 if (!msrpc_gen(ntlmssp_state, sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 277                         return NT_STATUS_NO_MEMORY;
 278                 }
 279
 280                 /* The order of these two operations matters - we must first seal the packet,
 281                    then seal the sequence number - this is because the ntlmv1_arc4_state is not
 282                    constant, but is is rather updated with each iteration */
 283
 284                 dump_arc4_state("ntlmv1 arc4 state:\n",
 285                                                 &ntlmssp_state->ntlmv1_arc4_state);
 286                 arcfour_crypt_sbox(&ntlmssp_state->ntlmv1_arc4_state, data, length);
 287
 288                 dump_arc4_state("ntlmv1 arc4 state:\n",
 289                                                 &ntlmssp_state->ntlmv1_arc4_state);
 290
 291                 arcfour_crypt_sbox(&ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 292
 293                 ntlmssp_state->ntlmv1_seq_num++;
 294         }
 295         dump_data_pw("ntlmssp signature\n", sig->data, sig->length);
 296         dump_data_pw("ntlmssp sealed data\n", data, length);
 297
 298         return NT_STATUS_OK;
 299 }
 300
 301 /**
 302  * Unseal data with the NTLMSSP algorithm
 303  *
 304  */
 305
 306 NTSTATUS ntlmssp_unseal_packet(struct ntlmssp_state *ntlmssp_state,
 307                                 uchar *data, size_t length,
 308                                 uchar *whole_pdu, size_t pdu_length,
 309                                 DATA_BLOB *sig)
 310 {
 311         if (!ntlmssp_state->session_key.length) {
 312                 DEBUG(3, ("NO session key, cannot unseal packet\n"));
 313                 return NT_STATUS_NO_USER_SESSION_KEY;
 314         }
 315
 316         DEBUG(10,("ntlmssp_unseal_packet: seal\n"));
 317         dump_data_pw("ntlmssp sealed data\n", data, length);
 318
 319         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 320                 /* First unseal the data. */
 321                 arcfour_crypt_sbox(&ntlmssp_state->recv_seal_arc4_state, data, length);
 322                 dump_data_pw("ntlmv2 clear data\n", data, length);
 323         } else {
 324                 arcfour_crypt_sbox(&ntlmssp_state->ntlmv1_arc4_state, data, length);
 325                 dump_data_pw("ntlmv1 clear data\n", data, length);
 326         }
 327         return ntlmssp_check_packet(ntlmssp_state, data, length, whole_pdu, pdu_length, sig);
 328 }
 329
 330 /**
 331    Initialise the state for NTLMSSP signing.
 332 */
 333 NTSTATUS ntlmssp_sign_init(struct ntlmssp_state *ntlmssp_state)
 334 {
 335         TALLOC_CTX *mem_ctx;
 336
 337         mem_ctx = talloc_init("weak_keys");
 338         if (!mem_ctx) {
 339                 return NT_STATUS_NO_MEMORY;
 340         }
 341
 342         DEBUG(3, ("NTLMSSP Sign/Seal - Initialising with flags:\n"));
 343         debug_ntlmssp_flags(ntlmssp_state->neg_flags);
 344
 345         if (ntlmssp_state->session_key.length < 8) {
 346                 TALLOC_FREE(mem_ctx);
 347                 DEBUG(3, ("NO session key, cannot intialise signing\n"));
 348                 return NT_STATUS_NO_USER_SESSION_KEY;
 349         }
 350
 351         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 352                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 353                 const char *send_sign_const;
 354                 const char *send_seal_const;
 355                 const char *recv_sign_const;
 356                 const char *recv_seal_const;
 357                 DATA_BLOB send_seal_key_blob, recv_seal_blob;
 358
 359                 switch (ntlmssp_state->role) {
 360                 case NTLMSSP_CLIENT:
 361                         send_sign_const = CLI_SIGN;
 362                         send_seal_const = CLI_SEAL;
 363                         recv_sign_const = SRV_SIGN;
 364                         recv_seal_const = SRV_SEAL;
 365                         break;
 366                 case NTLMSSP_SERVER:
 367                         send_sign_const = SRV_SIGN;
 368                         send_seal_const = SRV_SEAL;
 369                         recv_sign_const = CLI_SIGN;
 370                         recv_seal_const = CLI_SEAL;
 371                         break;
 372                 default:
 373                         TALLOC_FREE(mem_ctx);
 374                         return NT_STATUS_INTERNAL_ERROR;
 375                 }
 376
 377                 /**
 378                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 379                   We probably should have some parameters to control this, once we get NTLM2 working.
 380                 */
 381
 382                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 383                         ;
 384                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 385                         weak_session_key.length = 7;
 386                 } else { /* forty bits */
 387                         weak_session_key.length = 5;
 388                 }
 389
 390                 dump_data_pw("NTLMSSP weakend master key:\n",
 391                                 weak_session_key.data,
 392                                 weak_session_key.length);
 393
 394                 /* SEND: sign key */
 395                 calc_ntlmv2_key(ntlmssp_state->send_sign_key,
 396                                 ntlmssp_state->session_key, send_sign_const);
 397                 dump_data_pw("NTLMSSP send sign key:\n",
 398                                 ntlmssp_state->send_sign_key, 16);
 399
 400                 /* SEND: seal ARCFOUR pad */
 401                 calc_ntlmv2_key(ntlmssp_state->send_seal_key,
 402                                 weak_session_key, send_seal_const);
 403                 dump_data_pw("NTLMSSP send seal key:\n",
 404                                 ntlmssp_state->send_seal_key, 16);
 405
 406                 send_seal_key_blob.data = ntlmssp_state->send_seal_key;
 407                 send_seal_key_blob.length = 16;
 408                 arcfour_init(&ntlmssp_state->send_seal_arc4_state,
 409                              &send_seal_key_blob);
 410
 411                 dump_arc4_state("NTLMSSP send seal arc4 state:\n",
 412                              &ntlmssp_state->send_seal_arc4_state);
 413
 414                 /* RECV: sign key */
 415                 calc_ntlmv2_key(ntlmssp_state->recv_sign_key,
 416                                 ntlmssp_state->session_key, recv_sign_const);
 417                 dump_data_pw("NTLMSSP recv send sign key:\n",
 418                                 ntlmssp_state->recv_sign_key, 16);
 419
 420                 /* RECV: seal ARCFOUR pad */
 421                 calc_ntlmv2_key(ntlmssp_state->recv_seal_key,
 422                                 weak_session_key, recv_seal_const);
 423
 424                 dump_data_pw("NTLMSSP recv seal key:\n",
 425                                 ntlmssp_state->recv_seal_key, 16);
 426
 427                 recv_seal_blob.data = ntlmssp_state->recv_seal_key;
 428                 recv_seal_blob.length = 16;
 429                 arcfour_init(&ntlmssp_state->recv_seal_arc4_state,
 430                                 &recv_seal_blob);
 431
 432                 dump_arc4_state("NTLMSSP recv seal arc4 state:\n",
 433                              &ntlmssp_state->recv_seal_arc4_state);
 434
 435                 ntlmssp_state->ntlm2_send_seq_num = 0;
 436                 ntlmssp_state->ntlm2_recv_seq_num = 0;
 437
 438
 439         } else {
 440 #if 0
 441                 /* Hmmm. Shouldn't we also weaken keys for ntlmv1 ? JRA. */
 442
 443                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 444                 /**
 445                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 446                   We probably should have some parameters to control this, once we get NTLM2 working.
 447                 */
 448
 449                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 450                         ;
 451                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 452                         weak_session_key.length = 6;
 453                 } else { /* forty bits */
 454                         weak_session_key.length = 5;
 455                 }
 456                 dump_data_pw("NTLMSSP weakend master key:\n",
 457                                 weak_session_key.data,
 458                                 weak_session_key.length);
 459 #endif
 460
 461                 DATA_BLOB weak_session_key = ntlmssp_weaken_keys(ntlmssp_state, mem_ctx);
 462
 463                 DEBUG(5, ("NTLMSSP Sign/Seal - using NTLM1\n"));
 464
 465                 arcfour_init(&ntlmssp_state->ntlmv1_arc4_state,
 466                              &weak_session_key);
 467
 468                 dump_arc4_state("NTLMv1 arc4 state:\n",
 469                                 &ntlmssp_state->ntlmv1_arc4_state);
 470
 471                 ntlmssp_state->ntlmv1_seq_num = 0;
 472         }
 473
 474         TALLOC_FREE(mem_ctx);
 475         return NT_STATUS_OK;
 476 }