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 2 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, write to the Free Software Foundation,
  19  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  */
  21
  22 #include "includes.h"
  23
  24 #define CLI_SIGN "session key to client-to-server signing key magic constant"
  25 #define CLI_SEAL "session key to client-to-server sealing key magic constant"
  26 #define SRV_SIGN "session key to server-to-client signing key magic constant"
  27 #define SRV_SEAL "session key to server-to-client sealing key magic constant"
  28
  29 /**
  30  * Some notes on then NTLM2 code:
  31  *
  32  * NTLM2 is a AEAD system.  This means that the data encrypted is not
  33  * all the data that is signed.  In DCE-RPC case, the headers of the
  34  * DCE-RPC packets are also signed.  This prevents some of the
  35  * fun-and-games one might have by changing them.
  36  *
  37  */
  38
  39 static void calc_ntlmv2_key(unsigned char subkey[16],
  40                                 DATA_BLOB session_key,
  41                                 const char *constant)
  42 {
  43         struct MD5Context ctx3;
  44         MD5Init(&ctx3);
  45         MD5Update(&ctx3, session_key.data, session_key.length);
  46         MD5Update(&ctx3, (const unsigned char *)constant, strlen(constant)+1);
  47         MD5Final(subkey, &ctx3);
  48 }
  49
  50 enum ntlmssp_direction {
  51         NTLMSSP_SEND,
  52         NTLMSSP_RECEIVE
  53 };
  54
  55 static NTSTATUS ntlmssp_make_packet_signature(NTLMSSP_STATE *ntlmssp_state,
  56                                                 const uchar *data, size_t length,
  57                                                 const uchar *whole_pdu, size_t pdu_length,
  58                                                 enum ntlmssp_direction direction,
  59                                                 DATA_BLOB *sig,
  60                                                 BOOL encrypt_sig)
  61 {
  62         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
  63                 HMACMD5Context ctx;
  64                 uchar seq_num[4];
  65                 uchar digest[16];
  66
  67                 *sig = data_blob(NULL, NTLMSSP_SIG_SIZE);
  68                 if (!sig->data) {
  69                         return NT_STATUS_NO_MEMORY;
  70                 }
  71
  72                 switch (direction) {
  73                         case NTLMSSP_SEND:
  74                                 DEBUG(100,("ntlmssp_make_packet_signature: SEND seq = %u, len = %u, pdu_len = %u\n",
  75                                         ntlmssp_state->ntlm2_send_seq_num,
  76                                         (unsigned int)length,
  77                                         (unsigned int)pdu_length));
  78
  79                                 SIVAL(seq_num, 0, ntlmssp_state->ntlm2_send_seq_num);
  80                                 ntlmssp_state->ntlm2_send_seq_num++;
  81                                 hmac_md5_init_limK_to_64(ntlmssp_state->send_sign_key, 16, &ctx);
  82                                 break;
  83                         case NTLMSSP_RECEIVE:
  84
  85                                 DEBUG(100,("ntlmssp_make_packet_signature: RECV seq = %u, len = %u, pdu_len = %u\n",
  86                                         ntlmssp_state->ntlm2_recv_seq_num,
  87                                         (unsigned int)length,
  88                                         (unsigned int)pdu_length));
  89
  90                                 SIVAL(seq_num, 0, ntlmssp_state->ntlm2_recv_seq_num);
  91                                 ntlmssp_state->ntlm2_recv_seq_num++;
  92                                 hmac_md5_init_limK_to_64(ntlmssp_state->recv_sign_key, 16, &ctx);
  93                                 break;
  94                 }
  95
  96                 dump_data_pw("pdu data ", whole_pdu, pdu_length);
  97
  98                 hmac_md5_update(seq_num, 4, &ctx);
  99                 hmac_md5_update(whole_pdu, pdu_length, &ctx);
 100                 hmac_md5_final(digest, &ctx);
 101
 102                 if (encrypt_sig && (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH)) {
 103                         switch (direction) {
 104                         case NTLMSSP_SEND:
 105                                 smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state,  digest, 8);
 106                                 break;
 107                         case NTLMSSP_RECEIVE:
 108                                 smb_arc4_crypt(ntlmssp_state->recv_seal_arc4_state,  digest, 8);
 109                                 break;
 110                         }
 111                 }
 112
 113                 SIVAL(sig->data, 0, NTLMSSP_SIGN_VERSION);
 114                 memcpy(sig->data + 4, digest, 8);
 115                 memcpy(sig->data + 12, seq_num, 4);
 116
 117                 dump_data_pw("ntlmssp v2 sig ", sig->data, sig->length);
 118
 119         } else {
 120                 uint32 crc;
 121                 crc = crc32_calc_buffer((const char *)data, length);
 122                 if (!msrpc_gen(sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 123                         return NT_STATUS_NO_MEMORY;
 124                 }
 125
 126                 ntlmssp_state->ntlmv1_seq_num++;
 127
 128                 dump_data_pw("ntlmssp hash:\n", ntlmssp_state->ntlmv1_arc4_state,
 129                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 130                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 131         }
 132         return NT_STATUS_OK;
 133 }
 134
 135 NTSTATUS ntlmssp_sign_packet(NTLMSSP_STATE *ntlmssp_state,
 136                                     const uchar *data, size_t length,
 137                                     const uchar *whole_pdu, size_t pdu_length,
 138                                     DATA_BLOB *sig)
 139 {
 140         NTSTATUS nt_status;
 141
 142         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SIGN)) {
 143                 DEBUG(3, ("NTLMSSP Signing not negotiated - cannot sign packet!\n"));
 144                 return NT_STATUS_INVALID_PARAMETER;
 145         }
 146
 147         if (!ntlmssp_state->session_key.length) {
 148                 DEBUG(3, ("NO session key, cannot check sign packet\n"));
 149                 return NT_STATUS_NO_USER_SESSION_KEY;
 150         }
 151
 152         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 153                                                 data, length,
 154                                                 whole_pdu, pdu_length,
 155                                                 NTLMSSP_SEND, sig, True);
 156
 157         return nt_status;
 158 }
 159
 160 /**
 161  * Check the signature of an incoming packet
 162  * @note caller *must* check that the signature is the size it expects
 163  *
 164  */
 165
 166 NTSTATUS ntlmssp_check_packet(NTLMSSP_STATE *ntlmssp_state,
 167                                 const uchar *data, size_t length,
 168                                 const uchar *whole_pdu, size_t pdu_length,
 169                                 const DATA_BLOB *sig)
 170 {
 171         DATA_BLOB local_sig;
 172         NTSTATUS nt_status;
 173
 174         if (!ntlmssp_state->session_key.length) {
 175                 DEBUG(3, ("NO session key, cannot check packet signature\n"));
 176                 return NT_STATUS_NO_USER_SESSION_KEY;
 177         }
 178
 179         if (sig->length < 8) {
 180                 DEBUG(0, ("NTLMSSP packet check failed due to short signature (%lu bytes)!\n",
 181                           (unsigned long)sig->length));
 182         }
 183
 184         nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 185                                                 data, length,
 186                                                 whole_pdu, pdu_length,
 187                                                 NTLMSSP_RECEIVE, &local_sig, True);
 188
 189         if (!NT_STATUS_IS_OK(nt_status)) {
 190                 DEBUG(0, ("NTLMSSP packet check failed with %s\n", nt_errstr(nt_status)));
 191                 data_blob_free(&local_sig);
 192                 return nt_status;
 193         }
 194
 195         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 196                 if (local_sig.length != sig->length ||
 197                                 memcmp(local_sig.data, sig->data, sig->length) != 0) {
 198                         DEBUG(5, ("BAD SIG NTLM2: wanted signature of\n"));
 199                         dump_data(5, (const char *)local_sig.data, local_sig.length);
 200
 201                         DEBUG(5, ("BAD SIG: got signature of\n"));
 202                         dump_data(5, (const char *)sig->data, sig->length);
 203
 204                         DEBUG(0, ("NTLMSSP NTLM2 packet check failed due to invalid signature!\n"));
 205                         data_blob_free(&local_sig);
 206                         return NT_STATUS_ACCESS_DENIED;
 207                 }
 208         } else {
 209                 if (local_sig.length != sig->length ||
 210                                 memcmp(local_sig.data + 8, sig->data + 8, sig->length - 8) != 0) {
 211                         DEBUG(5, ("BAD SIG NTLM1: wanted signature of\n"));
 212                         dump_data(5, (const char *)local_sig.data, local_sig.length);
 213
 214                         DEBUG(5, ("BAD SIG: got signature of\n"));
 215                         dump_data(5, (const char *)sig->data, sig->length);
 216
 217                         DEBUG(0, ("NTLMSSP NTLM1 packet check failed due to invalid signature!\n"));
 218                         data_blob_free(&local_sig);
 219                         return NT_STATUS_ACCESS_DENIED;
 220                 }
 221         }
 222         dump_data_pw("checked ntlmssp signature\n", sig->data, sig->length);
 223         DEBUG(10,("ntlmssp_check_packet: NTLMSSP signature OK !\n"));
 224
 225         data_blob_free(&local_sig);
 226         return NT_STATUS_OK;
 227 }
 228
 229 /**
 230  * Seal data with the NTLMSSP algorithm
 231  *
 232  */
 233
 234 NTSTATUS ntlmssp_seal_packet(NTLMSSP_STATE *ntlmssp_state,
 235                              uchar *data, size_t length,
 236                              uchar *whole_pdu, size_t pdu_length,
 237                              DATA_BLOB *sig)
 238 {
 239         if (!(ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_SEAL)) {
 240                 DEBUG(3, ("NTLMSSP Sealing not negotiated - cannot seal packet!\n"));
 241                 return NT_STATUS_INVALID_PARAMETER;
 242         }
 243
 244         if (!ntlmssp_state->session_key.length) {
 245                 DEBUG(3, ("NO session key, cannot seal packet\n"));
 246                 return NT_STATUS_NO_USER_SESSION_KEY;
 247         }
 248
 249         DEBUG(10,("ntlmssp_seal_data: seal\n"));
 250         dump_data_pw("ntlmssp clear data\n", data, length);
 251         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 252                 /* The order of these two operations matters - we must first seal the packet,
 253                    then seal the sequence number - this is becouse the send_seal_hash is not
 254                    constant, but is is rather updated with each iteration */
 255                 NTSTATUS nt_status = ntlmssp_make_packet_signature(ntlmssp_state,
 256                                                         data, length,
 257                                                         whole_pdu, pdu_length,
 258                                                         NTLMSSP_SEND, sig, False);
 259                 if (!NT_STATUS_IS_OK(nt_status)) {
 260                         return nt_status;
 261                 }
 262
 263                 smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state, data, length);
 264                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_KEY_EXCH) {
 265                         smb_arc4_crypt(ntlmssp_state->send_seal_arc4_state, sig->data+4, 8);
 266                 }
 267         } else {
 268                 uint32 crc;
 269                 crc = crc32_calc_buffer((const char *)data, length);
 270                 if (!msrpc_gen(sig, "dddd", NTLMSSP_SIGN_VERSION, 0, crc, ntlmssp_state->ntlmv1_seq_num)) {
 271                         return NT_STATUS_NO_MEMORY;
 272                 }
 273
 274                 /* The order of these two operations matters - we must first seal the packet,
 275                    then seal the sequence number - this is becouse the ntlmv1_arc4_state is not
 276                    constant, but is is rather updated with each iteration */
 277
 278                 dump_data_pw("ntlmv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 279                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 280                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, data, length);
 281
 282                 dump_data_pw("ntlmv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 283                              sizeof(ntlmssp_state->ntlmv1_arc4_state));
 284
 285                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, sig->data+4, sig->length-4);
 286
 287                 ntlmssp_state->ntlmv1_seq_num++;
 288         }
 289         dump_data_pw("ntlmssp signature\n", sig->data, sig->length);
 290         dump_data_pw("ntlmssp sealed data\n", data, length);
 291
 292         return NT_STATUS_OK;
 293 }
 294
 295 /**
 296  * Unseal data with the NTLMSSP algorithm
 297  *
 298  */
 299
 300 NTSTATUS ntlmssp_unseal_packet(NTLMSSP_STATE *ntlmssp_state,
 301                                 uchar *data, size_t length,
 302                                 uchar *whole_pdu, size_t pdu_length,
 303                                 DATA_BLOB *sig)
 304 {
 305         if (!ntlmssp_state->session_key.length) {
 306                 DEBUG(3, ("NO session key, cannot unseal packet\n"));
 307                 return NT_STATUS_NO_USER_SESSION_KEY;
 308         }
 309
 310         DEBUG(10,("ntlmssp_unseal_packet: seal\n"));
 311         dump_data_pw("ntlmssp sealed data\n", data, length);
 312
 313         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 314                 /* First unseal the data. */
 315                 smb_arc4_crypt(ntlmssp_state->recv_seal_arc4_state, data, length);
 316                 dump_data_pw("ntlmv2 clear data\n", data, length);
 317         } else {
 318                 smb_arc4_crypt(ntlmssp_state->ntlmv1_arc4_state, data, length);
 319                 dump_data_pw("ntlmv1 clear data\n", data, length);
 320         }
 321         return ntlmssp_check_packet(ntlmssp_state, data, length, whole_pdu, pdu_length, sig);
 322 }
 323
 324 /**
 325    Initialise the state for NTLMSSP signing.
 326 */
 327 NTSTATUS ntlmssp_sign_init(NTLMSSP_STATE *ntlmssp_state)
 328 {
 329         unsigned char p24[24];
 330         TALLOC_CTX *mem_ctx;
 331         ZERO_STRUCT(p24);
 332
 333         mem_ctx = talloc_init("weak_keys");
 334         if (!mem_ctx) {
 335                 return NT_STATUS_NO_MEMORY;
 336         }
 337
 338         DEBUG(3, ("NTLMSSP Sign/Seal - Initialising with flags:\n"));
 339         debug_ntlmssp_flags(ntlmssp_state->neg_flags);
 340
 341         if (ntlmssp_state->session_key.length < 8) {
 342                 TALLOC_FREE(mem_ctx);
 343                 DEBUG(3, ("NO session key, cannot intialise signing\n"));
 344                 return NT_STATUS_NO_USER_SESSION_KEY;
 345         }
 346
 347         if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_NTLM2) {
 348                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 349                 const char *send_sign_const;
 350                 const char *send_seal_const;
 351                 const char *recv_sign_const;
 352                 const char *recv_seal_const;
 353
 354                 switch (ntlmssp_state->role) {
 355                 case NTLMSSP_CLIENT:
 356                         send_sign_const = CLI_SIGN;
 357                         send_seal_const = CLI_SEAL;
 358                         recv_sign_const = SRV_SIGN;
 359                         recv_seal_const = SRV_SEAL;
 360                         break;
 361                 case NTLMSSP_SERVER:
 362                         send_sign_const = SRV_SIGN;
 363                         send_seal_const = SRV_SEAL;
 364                         recv_sign_const = CLI_SIGN;
 365                         recv_seal_const = CLI_SEAL;
 366                         break;
 367                 default:
 368                         TALLOC_FREE(mem_ctx);
 369                         return NT_STATUS_INTERNAL_ERROR;
 370                 }
 371
 372                 /**
 373                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 374                   We probably should have some parameters to control this, once we get NTLM2 working.
 375                 */
 376
 377                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 378                         ;
 379                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 380                         weak_session_key.length = 7;
 381                 } else { /* forty bits */
 382                         weak_session_key.length = 5;
 383                 }
 384
 385                 dump_data_pw("NTLMSSP weakend master key:\n",
 386                                 weak_session_key.data,
 387                                 weak_session_key.length);
 388
 389                 /* SEND: sign key */
 390                 calc_ntlmv2_key(ntlmssp_state->send_sign_key,
 391                                 ntlmssp_state->session_key, send_sign_const);
 392                 dump_data_pw("NTLMSSP send sign key:\n",
 393                                 ntlmssp_state->send_sign_key, 16);
 394
 395                 /* SEND: seal ARCFOUR pad */
 396                 calc_ntlmv2_key(ntlmssp_state->send_seal_key,
 397                                 weak_session_key, send_seal_const);
 398                 dump_data_pw("NTLMSSP send seal key:\n",
 399                                 ntlmssp_state->send_seal_key, 16);
 400
 401                 smb_arc4_init(ntlmssp_state->send_seal_arc4_state,
 402                                 ntlmssp_state->send_seal_key, 16);
 403
 404                 dump_data_pw("NTLMSSP send seal arc4 state:\n",
 405                              ntlmssp_state->send_seal_arc4_state,
 406                              sizeof(ntlmssp_state->send_seal_arc4_state));
 407
 408                 /* RECV: sign key */
 409                 calc_ntlmv2_key(ntlmssp_state->recv_sign_key,
 410                                 ntlmssp_state->session_key, recv_sign_const);
 411                 dump_data_pw("NTLMSSP recv send sign key:\n",
 412                                 ntlmssp_state->recv_sign_key, 16);
 413
 414                 /* RECV: seal ARCFOUR pad */
 415                 calc_ntlmv2_key(ntlmssp_state->recv_seal_key,
 416                                 weak_session_key, recv_seal_const);
 417
 418                 dump_data_pw("NTLMSSP recv seal key:\n",
 419                                 ntlmssp_state->recv_seal_key, 16);
 420
 421                 smb_arc4_init(ntlmssp_state->recv_seal_arc4_state,
 422                                 ntlmssp_state->recv_seal_key, 16);
 423
 424                 dump_data_pw("NTLMSSP recv seal arc4 state:\n",
 425                              ntlmssp_state->recv_seal_arc4_state,
 426                              sizeof(ntlmssp_state->recv_seal_arc4_state));
 427
 428                 ntlmssp_state->ntlm2_send_seq_num = 0;
 429                 ntlmssp_state->ntlm2_recv_seq_num = 0;
 430
 431
 432         } else {
 433 #if 0
 434                 /* Hmmm. Shouldn't we also weaken keys for ntlmv1 ? JRA. */
 435
 436                 DATA_BLOB weak_session_key = ntlmssp_state->session_key;
 437                 /**
 438                   Weaken NTLMSSP keys to cope with down-level clients, servers and export restrictions.
 439                   We probably should have some parameters to control this, once we get NTLM2 working.
 440                 */
 441
 442                 if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_128) {
 443                         ;
 444                 } else if (ntlmssp_state->neg_flags & NTLMSSP_NEGOTIATE_56) {
 445                         weak_session_key.length = 6;
 446                 } else { /* forty bits */
 447                         weak_session_key.length = 5;
 448                 }
 449                 dump_data_pw("NTLMSSP weakend master key:\n",
 450                                 weak_session_key.data,
 451                                 weak_session_key.length);
 452 #endif
 453
 454                 DATA_BLOB weak_session_key = ntlmssp_weaken_keys(ntlmssp_state, mem_ctx);
 455
 456                 DEBUG(5, ("NTLMSSP Sign/Seal - using NTLM1\n"));
 457
 458                 smb_arc4_init(ntlmssp_state->ntlmv1_arc4_state,
 459                              weak_session_key.data, weak_session_key.length);
 460
 461                 dump_data_pw("NTLMv1 arc4 state:\n", ntlmssp_state->ntlmv1_arc4_state,
 462                                 sizeof(ntlmssp_state->ntlmv1_arc4_state));
 463
 464                 ntlmssp_state->ntlmv1_seq_num = 0;
 465         }
 466
 467         TALLOC_FREE(mem_ctx);
 468         return NT_STATUS_OK;
 469 }