source/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
  23 #define CLI_SIGN "session key to client-to-server signing key magic constant"
  24 #define CLI_SEAL "session key to client-to-server sealing key magic constant"
  25 #define SRV_SIGN "session key to server-to-client signing key magic constant"
  26 #define SRV_SEAL "session key to server-to-client sealing key magic constant"
  27
  28 /**
  29  * Some notes on then NTLM2 code:
  30  *
  31  * NTLM2 is a AEAD system.  This means that the data encrypted is not
  32  * all the data that is signed.  In DCE-RPC case, the headers of the
  33  * DCE-RPC packets are also signed.  This prevents some of the
  34  * fun-and-games one might have by changing them.
  35  *
  36  */
  37
  38 static void calc_ntlmv2_key(unsigned char subkey[16],
  39                                 DATA_BLOB session_key,
  40                                 const char *constant)
  41 {
  42         struct MD5Context ctx3;
  43         MD5Init(&ctx3);
  44         MD5Update(&ctx3, session_key.data, session_key.length);
  45         MD5Update(&ctx3, (const unsigned char *)constant, strlen(constant)+1);
  46         MD5Final(subkey, &ctx3);
  47 }
  48
  49 enum ntlmssp_direction {
  50         NTLMSSP_SEND,
  51         NTLMSSP_RECEIVE
  52 };
  53
  54 static NTSTATUS ntlmssp_make_packet_signature(NTLMSSP_STATE *ntlmssp_state,
  55                                                 const uchar *data, size_t length,
  56                                                 const uchar *whole_pdu, size_t pdu_length,
  57                                                 enum ntlmssp_direction direction,
  58                                                 DATA_BLOB *sig,
  59                                                 bool encrypt_sig)
  60 {
  61         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
  62                 HMACMD5Context ctx;
  63                 uchar seq_num[4];
  64                 uchar digest[16];
  65
  66                 *sig = data_blob(NULL, NTLMSSP_SIG_SIZE);
  67                 if (!sig->data) {
  68                         return NT_STATUS_NO_MEMORY;
  69                 }
  70
  71                 switch (direction) {
  72                         case NTLMSSP_SEND:
  73                                 DEBUG(100,("ntlmssp_make_packet_signature: SEND seq = %u, len = %u, pdu_len = %u\n",
  74                                         ntlmssp_state->ntlm2_send_seq_num,
  75                                         (unsigned int)length,
  76                                         (unsigned int)pdu_length));
  77
  78                                 SIVAL(seq_num, 0, ntlmssp_state->ntlm2_send_seq_num);
  79                                 ntlmssp_state->ntlm2_send_seq_num++;
  80                                 hmac_md5_init_limK_to_64(ntlmssp_state->send_sign_key, 16, &ctx);
  81                                 break;
  82                         case NTLMSSP_RECEIVE:
  83
  84                                 DEBUG(100,("ntlmssp_make_packet_signature: RECV seq = %u, len = %u, pdu_len = %u\n",
  85                                         ntlmssp_state->ntlm2_recv_seq_num,
  86                                         (unsigned int)length,
  87                                         (unsigned int)pdu_length));
  88
  89                                 SIVAL(seq_num, 0, ntlmssp_state->ntlm2_recv_seq_num);
  90                                 ntlmssp_state->ntlm2_recv_seq_num++;
  91                                 hmac_md5_init_limK_to_64(ntlmssp_state->recv_sign_key, 16, &ctx);
  92                                 break;
  93                 }
  94
  95                 dump_data_pw("pdu data ", whole_pdu, pdu_length);
  96
  97                 hmac_md5_update(seq_num, 4, &ctx);
  98                 hmac_md5_update(whole_pdu, pdu_length, &ctx);
  99                 hmac_md5_final(digest, &ctx);
 100
 101                 if (encrypt_sig && (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH)) {
 102                         switch (direction) {
 103                         case NTLMSSP_SEND:
 104                                 smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state,  digest, 8);
 105                                 break;
 106                         case NTLMSSP_RECEIVE:
 107                                 smb_arc4_crypt(ntlmssp_state->recv_seal_arc4_state,  digest, 8);
 108                                 break;
 109                         }
 110                 }
 111
 112                 SIVAL(sig->data, 0, NTLMSSP_SIGN_VERSION);
 113                 memcpy(sig->data + 4, digest, 8);
 114                 memcpy(sig->data + 12, seq_num, 4);
 115
 116                 dump_data_pw("ntlmssp v2 sig ", sig->data, sig->length);
 117
 118         } else {
 119                 uint32 crc;
 120                 crc = crc32_calc_buffer((const char *)data, length);
 121                 if (!msrpc_gen(sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 122                         return NT_STATUS_NO_MEMORY;
 123                 }
 124
 125                 ntlmssp_state->ntlmv1_seq_num++;
 126
 127                 dump_data_pw("ntlmssp hash:\n", ntlmssp_state->ntlmv1_arc4_state,
 128                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 129                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 130         }
 131         return NT_STATUS_OK;
 132 }
 133
 134 NTSTATUS ntlmssp_sign_packet(NTLMSSP_STATE *ntlmssp_state,
 135                                     const uchar *data, size_t length,
 136                                     const uchar *whole_pdu, size_t pdu_length,
 137                                     DATA_BLOB *sig)
 138 {
 139         NTSTATUS nt_status;
 140
 141         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN)) {
 142                 DEBUG(3, ("NTLMSSP Signing not negotiated - cannot sign packet!\n"));
 143                 return NT_STATUS_INVALID_PARAMETER;
 144         }
 145
 146         if (!ntlmssp_state->session_key.length) {
 147                 DEBUG(3, ("NO session key, cannot check sign packet\n"));
 148                 return NT_STATUS_NO_USER_SESSION_KEY;
 149         }
 150
 151         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 152                                                 data, length,
 153                                                 whole_pdu, pdu_length,
 154                                                 NTLMSSP_SEND, sig, True);
 155
 156         return nt_status;
 157 }
 158
 159 /**
 160  * Check the signature of an incoming packet
 161  * @note caller *must* check that the signature is the size it expects
 162  *
 163  */
 164
 165 NTSTATUS ntlmssp_check_packet(NTLMSSP_STATE *ntlmssp_state,
 166                                 const uchar *data, size_t length,
 167                                 const uchar *whole_pdu, size_t pdu_length,
 168                                 const DATA_BLOB *sig)
 169 {
 170         DATA_BLOB local_sig;
 171         NTSTATUS nt_status;
 172
 173         if (!ntlmssp_state->session_key.length) {
 174                 DEBUG(3, ("NO session key, cannot check packet signature\n"));
 175                 return NT_STATUS_NO_USER_SESSION_KEY;
 176         }
 177
 178         if (sig->length < 8) {
 179                 DEBUG(0, ("NTLMSSP packet check failed due to short signature (%lu bytes)!\n",
 180                           (unsigned long)sig->length));
 181         }
 182
 183         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 184                                                 data, length,
 185                                                 whole_pdu, pdu_length,
 186                                                 NTLMSSP_RECEIVE, &local_sig, True);
 187
 188         if (!NT_STATUS_IS_OK(nt_status)) {
 189                 DEBUG(0, ("NTLMSSP packet check failed with %s\n", nt_errstr(nt_status)));
 190                 data_blob_free(&local_sig);
 191                 return nt_status;
 192         }
 193
 194         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 195                 if (local_sig.length != sig->length ||
 196                                 memcmp(local_sig.data, sig->data, sig->length) != 0) {
 197                         DEBUG(5, ("BAD SIG NTLM2: wanted signature of\n"));
 198                         dump_data(5, local_sig.data, local_sig.length);
 199
 200                         DEBUG(5, ("BAD SIG: got signature of\n"));
 201                         dump_data(5, sig->data, sig->length);
 202
 203                         DEBUG(0, ("NTLMSSP NTLM2 packet check failed due to invalid signature!\n"));
 204                         data_blob_free(&local_sig);
 205                         return NT_STATUS_ACCESS_DENIED;
 206                 }
 207         } else {
 208                 if (local_sig.length != sig->length ||
 209                                 memcmp(local_sig.data + 8, sig->data + 8, sig->length - 8) != 0) {
 210                         DEBUG(5, ("BAD SIG NTLM1: wanted signature of\n"));
 211                         dump_data(5, local_sig.data, local_sig.length);
 212
 213                         DEBUG(5, ("BAD SIG: got signature of\n"));
 214                         dump_data(5, sig->data, sig->length);
 215
 216                         DEBUG(0, ("NTLMSSP NTLM1 packet check failed due to invalid signature!\n"));
 217                         data_blob_free(&local_sig);
 218                         return NT_STATUS_ACCESS_DENIED;
 219                 }
 220         }
 221         dump_data_pw("checked ntlmssp signature\n", sig->data, sig->length);
 222         DEBUG(10,("ntlmssp_check_packet: NTLMSSP signature OK !\n"));
 223
 224         data_blob_free(&local_sig);
 225         return NT_STATUS_OK;
 226 }
 227
 228 /**
 229  * Seal data with the NTLMSSP algorithm
 230  *
 231  */
 232
 233 NTSTATUS ntlmssp_seal_packet(NTLMSSP_STATE *ntlmssp_state,
 234                              uchar *data, size_t length,
 235                              uchar *whole_pdu, size_t pdu_length,
 236                              DATA_BLOB *sig)
 237 {
 238         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL)) {
 239                 DEBUG(3, ("NTLMSSP Sealing not negotiated - cannot seal packet!\n"));
 240                 return NT_STATUS_INVALID_PARAMETER;
 241         }
 242
 243         if (!ntlmssp_state->session_key.length) {
 244                 DEBUG(3, ("NO session key, cannot seal packet\n"));
 245                 return NT_STATUS_NO_USER_SESSION_KEY;
 246         }
 247
 248         DEBUG(10,("ntlmssp_seal_data: seal\n"));
 249         dump_data_pw("ntlmssp clear data\n", data, length);
 250         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 251                 /* The order of these two operations matters - we must first seal the packet,
 252                    then seal the sequence number - this is becouse the send_seal_hash is not
 253                    constant, but is is rather updated with each iteration */
 254                 NTSTATUS nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 255                                                         data, length,
 256                                                         whole_pdu, pdu_length,
 257                                                         NTLMSSP_SEND, sig, False);
 258                 if (!NT_STATUS_IS_OK(nt_status)) {
 259                         return nt_status;
 260                 }
 261
 262                 smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state, data, length);
 263                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH) {
 264                         smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state, sig->data+4, 8);
 265                 }
 266         } else {
 267                 uint32 crc;
 268                 crc = crc32_calc_buffer((const char *)data, length);
 269                 if (!msrpc_gen(sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 270                         return NT_STATUS_NO_MEMORY;
 271                 }
 272
 273                 /* The order of these two operations matters - we must first seal the packet,
 274                    then seal the sequence number - this is becouse the ntlmv1_arc4_state is not
 275                    constant, but is is rather updated with each iteration */
 276
 277                 dump_data_pw("ntlmv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 278                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 279                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, data, length);
 280
 281                 dump_data_pw("ntlmv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 282                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 283
 284                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 285
 286                 ntlmssp_state->ntlmv1_seq_num++;
 287         }
 288         dump_data_pw("ntlmssp signature\n", sig->data, sig->length);
 289         dump_data_pw("ntlmssp sealed data\n", data, length);
 290
 291         return NT_STATUS_OK;
 292 }
 293
 294 /**
 295  * Unseal data with the NTLMSSP algorithm
 296  *
 297  */
 298
 299 NTSTATUS ntlmssp_unseal_packet(NTLMSSP_STATE *ntlmssp_state,
 300                                 uchar *data, size_t length,
 301                                 uchar *whole_pdu, size_t pdu_length,
 302                                 DATA_BLOB *sig)
 303 {
 304         if (!ntlmssp_state->session_key.length) {
 305                 DEBUG(3, ("NO session key, cannot unseal packet\n"));
 306                 return NT_STATUS_NO_USER_SESSION_KEY;
 307         }
 308
 309         DEBUG(10,("ntlmssp_unseal_packet: seal\n"));
 310         dump_data_pw("ntlmssp sealed data\n", data, length);
 311
 312         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 313                 /* First unseal the data. */
 314                 smb_arc4_crypt(ntlmssp_state->recv_seal_arc4_state, data, length);
 315                 dump_data_pw("ntlmv2 clear data\n", data, length);
 316         } else {
 317                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, data, length);
 318                 dump_data_pw("ntlmv1 clear data\n", data, length);
 319         }
 320         return ntlmssp_check_packet(ntlmssp_state, data, length, whole_pdu, pdu_length, sig);
 321 }
 322
 323 /**
 324    Initialise the state for NTLMSSP signing.
 325 */
 326 NTSTATUS ntlmssp_sign_init(NTLMSSP_STATE *ntlmssp_state)
 327 {
 328         unsigned char p24[24];
 329         TALLOC_CTX *mem_ctx;
 330         ZERO_STRUCT(p24);
 331
 332         mem_ctx = talloc_init("weak_keys");
 333         if (!mem_ctx) {
 334                 return NT_STATUS_NO_MEMORY;
 335         }
 336
 337         DEBUG(3, ("NTLMSSP Sign/Seal - Initialising with flags:\n"));
 338         debug_ntlmssp_flags(ntlmssp_state->neg_flags);
 339
 340         if (ntlmssp_state->session_key.length < 8) {
 341                 TALLOC_FREE(mem_ctx);
 342                 DEBUG(3, ("NO session key, cannot intialise signing\n"));
 343                 return NT_STATUS_NO_USER_SESSION_KEY;
 344         }
 345
 346         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 347                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 348                 const char *send_sign_const;
 349                 const char *send_seal_const;
 350                 const char *recv_sign_const;
 351                 const char *recv_seal_const;
 352
 353                 switch (ntlmssp_state->role) {
 354                 case NTLMSSP_CLIENT:
 355                         send_sign_const = CLI_SIGN;
 356                         send_seal_const = CLI_SEAL;
 357                         recv_sign_const = SRV_SIGN;
 358                         recv_seal_const = SRV_SEAL;
 359                         break;
 360                 case NTLMSSP_SERVER:
 361                         send_sign_const = SRV_SIGN;
 362                         send_seal_const = SRV_SEAL;
 363                         recv_sign_const = CLI_SIGN;
 364                         recv_seal_const = CLI_SEAL;
 365                         break;
 366                 default:
 367                         TALLOC_FREE(mem_ctx);
 368                         return NT_STATUS_INTERNAL_ERROR;
 369                 }
 370
 371                 /**
 372                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 373                   We probably should have some parameters to control this, once we get NTLM2 working.
 374                 */
 375
 376                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 377                         ;
 378                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 379                         weak_session_key.length = 7;
 380                 } else { /* forty bits */
 381                         weak_session_key.length = 5;
 382                 }
 383
 384                 dump_data_pw("NTLMSSP weakend master key:\n",
 385                                 weak_session_key.data,
 386                                 weak_session_key.length);
 387
 388                 /* SEND: sign key */
 389                 calc_ntlmv2_key(ntlmssp_state->send_sign_key,
 390                                 ntlmssp_state->session_key, send_sign_const);
 391                 dump_data_pw("NTLMSSP send sign key:\n",
 392                                 ntlmssp_state->send_sign_key, 16);
 393
 394                 /* SEND: seal ARCFOUR pad */
 395                 calc_ntlmv2_key(ntlmssp_state->send_seal_key,
 396                                 weak_session_key, send_seal_const);
 397                 dump_data_pw("NTLMSSP send seal key:\n",
 398                                 ntlmssp_state->send_seal_key, 16);
 399
 400                 smb_arc4_init(ntlmssp_state->send_seal_arc4_state,
 401                                 ntlmssp_state->send_seal_key, 16);
 402
 403                 dump_data_pw("NTLMSSP send seal arc4 state:\n",
 404                              ntlmssp_state->send_seal_arc4_state,
 405                              sizeof(ntlmssp_state->send_seal_arc4_state));
 406
 407                 /* RECV: sign key */
 408                 calc_ntlmv2_key(ntlmssp_state->recv_sign_key,
 409                                 ntlmssp_state->session_key, recv_sign_const);
 410                 dump_data_pw("NTLMSSP recv send sign key:\n",
 411                                 ntlmssp_state->recv_sign_key, 16);
 412
 413                 /* RECV: seal ARCFOUR pad */
 414                 calc_ntlmv2_key(ntlmssp_state->recv_seal_key,
 415                                 weak_session_key, recv_seal_const);
 416
 417                 dump_data_pw("NTLMSSP recv seal key:\n",
 418                                 ntlmssp_state->recv_seal_key, 16);
 419
 420                 smb_arc4_init(ntlmssp_state->recv_seal_arc4_state,
 421                                 ntlmssp_state->recv_seal_key, 16);
 422
 423                 dump_data_pw("NTLMSSP recv seal arc4 state:\n",
 424                              ntlmssp_state->recv_seal_arc4_state,
 425                              sizeof(ntlmssp_state->recv_seal_arc4_state));
 426
 427                 ntlmssp_state->ntlm2_send_seq_num = 0;
 428                 ntlmssp_state->ntlm2_recv_seq_num = 0;
 429
 430
 431         } else {
 432 #if 0
 433                 /* Hmmm. Shouldn't we also weaken keys for ntlmv1 ? JRA. */
 434
 435                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 436                 /**
 437                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 438                   We probably should have some parameters to control this, once we get NTLM2 working.
 439                 */
 440
 441                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 442                         ;
 443                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 444                         weak_session_key.length = 6;
 445                 } else { /* forty bits */
 446                         weak_session_key.length = 5;
 447                 }
 448                 dump_data_pw("NTLMSSP weakend master key:\n",
 449                                 weak_session_key.data,
 450                                 weak_session_key.length);
 451 #endif
 452
 453                 DATA_BLOB weak_session_key = ntlmssp_weaken_keys(ntlmssp_state, mem_ctx);
 454
 455                 DEBUG(5, ("NTLMSSP Sign/Seal - using NTLM1\n"));
 456
 457                 smb_arc4_init(ntlmssp_state->ntlmv1_arc4_state,
 458                              weak_session_key.data, weak_session_key.length);
 459
 460                 dump_data_pw("NTLMv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 461                                 sizeof(ntlmssp_state->ntlmv1_arc4_state));
 462
 463                 ntlmssp_state->ntlmv1_seq_num = 0;
 464         }
 465
 466         TALLOC_FREE(mem_ctx);
 467         return NT_STATUS_OK;
 468 }