summaryrefslogtreecommitdiff
path: root/source3/libsmb/smb_signing.c
blob: c5b1d4458653fabdf0b938e7453968828e18370c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
/* 
   Unix SMB/CIFS implementation.
   SMB Signing Code
   Copyright (C) Jeremy Allison 2003.
   Copyright (C) Andrew Bartlett <abartlet@samba.org> 2002-2003
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

/* Lookup a packet's MID (multiplex id) and figure out it's sequence number */
struct outstanding_packet_lookup {
	struct outstanding_packet_lookup *prev, *next;
	uint16 mid;
	uint32 reply_seq_num;
	BOOL can_delete; /* Set to False in trans state. */
};

struct smb_basic_signing_context {
	DATA_BLOB mac_key;
	uint32 send_seq_num;
	struct outstanding_packet_lookup *outstanding_packet_list;
};

static BOOL store_sequence_for_reply(struct outstanding_packet_lookup **list, 
				     uint16 mid, uint32 reply_seq_num)
{
	struct outstanding_packet_lookup *t;

	/* Ensure we only add a mid once. */
	for (t = *list; t; t = t->next) {
		if (t->mid == mid) {
			return False;
		}
	}

	t = SMB_XMALLOC_P(struct outstanding_packet_lookup);
	ZERO_STRUCTP(t);

	t->mid = mid;
	t->reply_seq_num = reply_seq_num;
	t->can_delete = True;

	/*
	 * Add to the *start* of the list not the end of the list.
	 * This ensures that the *last* send sequence with this mid
	 * is returned by preference.
	 * This can happen if the mid wraps and one of the early
	 * mid numbers didn't get a reply and is still lurking on
	 * the list. JRA. Found by Fran Fabrizio <fran@cis.uab.edu>.
	 */

	DLIST_ADD(*list, t);
	DEBUG(10,("store_sequence_for_reply: stored seq = %u mid = %u\n",
			(unsigned int)reply_seq_num, (unsigned int)mid ));
	return True;
}

static BOOL get_sequence_for_reply(struct outstanding_packet_lookup **list,
				   uint16 mid, uint32 *reply_seq_num)
{
	struct outstanding_packet_lookup *t;

	for (t = *list; t; t = t->next) {
		if (t->mid == mid) {
			*reply_seq_num = t->reply_seq_num;
			DEBUG(10,("get_sequence_for_reply: found seq = %u mid = %u\n",
				(unsigned int)t->reply_seq_num, (unsigned int)t->mid ));
			if (t->can_delete) {
				DLIST_REMOVE(*list, t);
				SAFE_FREE(t);
			}
			return True;
		}
	}
	return False;
}

static BOOL set_sequence_can_delete_flag(struct outstanding_packet_lookup **list, uint16 mid, BOOL can_delete_entry)
{
	struct outstanding_packet_lookup *t;

	for (t = *list; t; t = t->next) {
		if (t->mid == mid) {
			t->can_delete = can_delete_entry;
			return True;
		}
	}
	return False;
}

/***********************************************************
 SMB signing - Common code before we set a new signing implementation
************************************************************/

static BOOL cli_set_smb_signing_common(struct cli_state *cli) 
{
	if (!cli->sign_info.allow_smb_signing) {
		return False;
	}

	if (!cli->sign_info.negotiated_smb_signing 
	    && !cli->sign_info.mandatory_signing) {
		return False;
	}

	if (cli->sign_info.doing_signing) {
		return False;
	}
	
	if (cli->sign_info.free_signing_context)
		cli->sign_info.free_signing_context(&cli->sign_info);

	/* These calls are INCOMPATIBLE with SMB signing */
	cli->readbraw_supported = False;
	cli->writebraw_supported = False;
	
	return True;
}

/***********************************************************
 SMB signing - Common code for 'real' implementations
************************************************************/

static BOOL set_smb_signing_real_common(struct smb_sign_info *si)
{
	if (si->mandatory_signing) {
		DEBUG(5, ("Mandatory SMB signing enabled!\n"));
	}

	si->doing_signing = True;
	DEBUG(5, ("SMB signing enabled!\n"));

	return True;
}

static void mark_packet_signed(char *outbuf)
{
	uint16 flags2;
	flags2 = SVAL(outbuf,smb_flg2);
	flags2 |= FLAGS2_SMB_SECURITY_SIGNATURES;
	SSVAL(outbuf,smb_flg2, flags2);
}

/***********************************************************
 SMB signing - NULL implementation - calculate a MAC to send.
************************************************************/

static void null_sign_outgoing_message(char *outbuf, struct smb_sign_info *si)
{
	/* we can't zero out the sig, as we might be trying to send a
	   session request - which is NBT-level, not SMB level and doesn't
	   have the field */
	return;
}

/***********************************************************
 SMB signing - NULL implementation - check a MAC sent by server.
************************************************************/

static BOOL null_check_incoming_message(const char *inbuf,
					struct smb_sign_info *si,
					BOOL must_be_ok)
{
	return True;
}

/***********************************************************
 SMB signing - NULL implementation - free signing context
************************************************************/

static void null_free_signing_context(struct smb_sign_info *si)
{
	return;
}

/**
 SMB signing - NULL implementation - setup the MAC key.

 @note Used as an initialisation only - it will not correctly
       shut down a real signing mechanism
*/

static BOOL null_set_signing(struct smb_sign_info *si)
{
	si->signing_context = NULL;
	
	si->sign_outgoing_message = null_sign_outgoing_message;
	si->check_incoming_message = null_check_incoming_message;
	si->free_signing_context = null_free_signing_context;

	return True;
}

/**
 * Free the signing context
 */
 
static void free_signing_context(struct smb_sign_info *si)
{
	if (si->free_signing_context) {
		si->free_signing_context(si);
		si->signing_context = NULL;
	}

	null_set_signing(si);
}


static BOOL signing_good(const char *inbuf, struct smb_sign_info *si,
			 BOOL good, uint32 seq, BOOL must_be_ok)
{
	if (good) {

		if (!si->doing_signing) {
			si->doing_signing = True;
		}
		
		if (!si->seen_valid) {
			si->seen_valid = True;
		}

	} else {
		if (!si->mandatory_signing && !si->seen_valid) {

			if (!must_be_ok) {
				return True;
			}
			/* Non-mandatory signing - just turn off if this is the first bad packet.. */
			DEBUG(5, ("srv_check_incoming_message: signing negotiated but not required and peer\n"
				  "isn't sending correct signatures. Turning off.\n"));
			si->negotiated_smb_signing = False;
			si->allow_smb_signing = False;
			si->doing_signing = False;
			free_signing_context(si);
			return True;
		} else if (!must_be_ok) {
			/* This packet is known to be unsigned */
			return True;
		} else {
			/* Mandatory signing or bad packet after signing started - fail and disconnect. */
			if (seq)
				DEBUG(0, ("signing_good: BAD SIG: seq %u\n", (unsigned int)seq));
			return False;
		}
	}
	return True;
}	

/***********************************************************
 SMB signing - Simple implementation - calculate a MAC on the packet
************************************************************/

static void simple_packet_signature(struct smb_basic_signing_context *data, 
				    const uchar *buf, uint32 seq_number, 
				    unsigned char calc_md5_mac[16])
{
	const size_t offset_end_of_sig = (smb_ss_field + 8);
	unsigned char sequence_buf[8];
	struct MD5Context md5_ctx;
#if 0
        /* JRA - apparently this is incorrect. */
	unsigned char key_buf[16];
#endif

	/*
	 * Firstly put the sequence number into the first 4 bytes.
	 * and zero out the next 4 bytes.
	 *
	 * We do this here, to avoid modifying the packet.
	 */

	DEBUG(10,("simple_packet_signature: sequence number %u\n", seq_number ));

	SIVAL(sequence_buf, 0, seq_number);
	SIVAL(sequence_buf, 4, 0);

	/* Calculate the 16 byte MAC - but don't alter the data in the
	   incoming packet.
	   
	   This makes for a bit of fussing about, but it's not too bad.
	*/
	MD5Init(&md5_ctx);

	/* intialise with the key */
	MD5Update(&md5_ctx, data->mac_key.data, data->mac_key.length); 
#if 0
	/* JRA - apparently this is incorrect. */
	/* NB. When making and verifying SMB signatures, Windows apparently
		zero-pads the key to 128 bits if it isn't long enough.
		From Nalin Dahyabhai <nalin@redhat.com> */
	if (data->mac_key.length < sizeof(key_buf)) {
		memset(key_buf, 0, sizeof(key_buf));
		MD5Update(&md5_ctx, key_buf, sizeof(key_buf) - data->mac_key.length);
	}
#endif

	/* copy in the first bit of the SMB header */
	MD5Update(&md5_ctx, buf + 4, smb_ss_field - 4);

	/* copy in the sequence number, instead of the signature */
	MD5Update(&md5_ctx, sequence_buf, sizeof(sequence_buf));

	/* copy in the rest of the packet in, skipping the signature */
	MD5Update(&md5_ctx, buf + offset_end_of_sig, 
		  smb_len(buf) - (offset_end_of_sig - 4));

	/* calculate the MD5 sig */ 
	MD5Final(calc_md5_mac, &md5_ctx);
}


/***********************************************************
 SMB signing - Client implementation - send the MAC.
************************************************************/

static void client_sign_outgoing_message(char *outbuf, struct smb_sign_info *si)
{
	unsigned char calc_md5_mac[16];
	struct smb_basic_signing_context *data =
		(struct smb_basic_signing_context *)si->signing_context;

	if (!si->doing_signing)
		return;

	/* JRA Paranioa test - we should be able to get rid of this... */
	if (smb_len(outbuf) < (smb_ss_field + 8 - 4)) {
		DEBUG(1, ("client_sign_outgoing_message: Logic error. Can't check signature on short packet! smb_len = %u\n",
					smb_len(outbuf) ));
		abort();
	}

	/* mark the packet as signed - BEFORE we sign it...*/
	mark_packet_signed(outbuf);

	simple_packet_signature(data, (const unsigned char *)outbuf,
				data->send_seq_num, calc_md5_mac);

	DEBUG(10, ("client_sign_outgoing_message: sent SMB signature of\n"));
	dump_data(10, calc_md5_mac, 8);

	memcpy(&outbuf[smb_ss_field], calc_md5_mac, 8);

/*	cli->outbuf[smb_ss_field+2]=0; 
	Uncomment this to test if the remote server actually verifies signatures...*/

	/* Instead of re-introducing the trans_info_conect we
	   used to have here, we use the fact that during a
	   SMBtrans/SMBtrans2/SMBnttrans send that the mid stays
	   constant. This means that calling store_sequence_for_reply()
	   will return False for all trans secondaries, as the mid is already
	   on the stored sequence list. As the send_seqence_number must
	   remain constant for all primary+secondary trans sends, we
	   only increment the send sequence number when we successfully
	   add a new entry to the outstanding sequence list. This means
	   I can isolate the fix here rather than re-adding the trans
	   signing on/off calls in libsmb/clitrans2.c JRA.
	 */
	
	if (store_sequence_for_reply(&data->outstanding_packet_list, SVAL(outbuf,smb_mid), data->send_seq_num + 1)) {
		data->send_seq_num += 2;
	}
}

/***********************************************************
 SMB signing - Client implementation - check a MAC sent by server.
************************************************************/

static BOOL client_check_incoming_message(const char *inbuf,
					  struct smb_sign_info *si,
					  BOOL must_be_ok)
{
	BOOL good;
	uint32 reply_seq_number;
	unsigned char calc_md5_mac[16];
	unsigned char *server_sent_mac;

	struct smb_basic_signing_context *data =
		(struct smb_basic_signing_context *)si->signing_context;

	if (!si->doing_signing)
		return True;

	if (smb_len(inbuf) < (smb_ss_field + 8 - 4)) {
		DEBUG(1, ("client_check_incoming_message: Can't check signature on short packet! smb_len = %u\n", smb_len(inbuf)));
		return False;
	}

	if (!get_sequence_for_reply(&data->outstanding_packet_list, SVAL(inbuf, smb_mid), &reply_seq_number)) {
		DEBUG(1, ("client_check_incoming_message: received message "
			"with mid %u with no matching send record.\n", (unsigned int)SVAL(inbuf, smb_mid) ));
		return False;
	}

	simple_packet_signature(data, (const unsigned char *)inbuf,
				reply_seq_number, calc_md5_mac);

	server_sent_mac = (unsigned char *)&inbuf[smb_ss_field];
	good = (memcmp(server_sent_mac, calc_md5_mac, 8) == 0);
	
	if (!good) {
		DEBUG(5, ("client_check_incoming_message: BAD SIG: wanted SMB signature of\n"));
		dump_data(5, calc_md5_mac, 8);
		
		DEBUG(5, ("client_check_incoming_message: BAD SIG: got SMB signature of\n"));
		dump_data(5, server_sent_mac, 8);
#if 1 /* JRATEST */
		{
			int i;
			for (i = -5; i < 5; i++) {
				simple_packet_signature(data, (const unsigned char *)inbuf, reply_seq_number+i, calc_md5_mac);
				if (memcmp(server_sent_mac, calc_md5_mac, 8) == 0) {
					DEBUG(0,("client_check_incoming_message: out of seq. seq num %u matches. \
We were expecting seq %u\n", reply_seq_number+i, reply_seq_number ));
					break;
				}
			}
		}
#endif /* JRATEST */

	} else {
		DEBUG(10, ("client_check_incoming_message: seq %u: got good SMB signature of\n", (unsigned int)reply_seq_number));
		dump_data(10, server_sent_mac, 8);
	}
	return signing_good(inbuf, si, good, reply_seq_number, must_be_ok);
}

/***********************************************************
 SMB signing - Simple implementation - free signing context
************************************************************/

static void simple_free_signing_context(struct smb_sign_info *si)
{
	struct smb_basic_signing_context *data =
		(struct smb_basic_signing_context *)si->signing_context;
	struct outstanding_packet_lookup *list;
	struct outstanding_packet_lookup *next;
	
	for (list = data->outstanding_packet_list; list; list = next) {
		next = list->next;
		DLIST_REMOVE(data->outstanding_packet_list, list);
		SAFE_FREE(list);
	}

	data_blob_free(&data->mac_key);

	SAFE_FREE(si->signing_context);

	return;
}

/***********************************************************
 SMB signing - Simple implementation - setup the MAC key.
************************************************************/

BOOL cli_simple_set_signing(struct cli_state *cli,
			    const DATA_BLOB user_session_key,
			    const DATA_BLOB response)
{
	struct smb_basic_signing_context *data;

	if (!user_session_key.length)
		return False;

	if (!cli_set_smb_signing_common(cli)) {
		return False;
	}

	if (!set_smb_signing_real_common(&cli->sign_info)) {
		return False;
	}

	data = SMB_XMALLOC_P(struct smb_basic_signing_context);
	memset(data, '\0', sizeof(*data));

	cli->sign_info.signing_context = data;
	
	data->mac_key = data_blob(NULL, response.length + user_session_key.length);

	memcpy(&data->mac_key.data[0], user_session_key.data, user_session_key.length);

	DEBUG(10, ("cli_simple_set_signing: user_session_key\n"));
	dump_data(10, user_session_key.data, user_session_key.length);

	if (response.length) {
		memcpy(&data->mac_key.data[user_session_key.length],response.data, response.length);
		DEBUG(10, ("cli_simple_set_signing: response_data\n"));
		dump_data(10, response.data, response.length);
	} else {
		DEBUG(10, ("cli_simple_set_signing: NULL response_data\n"));
	}

	dump_data_pw("MAC ssession key is:\n", data->mac_key.data, data->mac_key.length);

	/* Initialise the sequence number */
	data->send_seq_num = 0;

	/* Initialise the list of outstanding packets */
	data->outstanding_packet_list = NULL;

	cli->sign_info.sign_outgoing_message = client_sign_outgoing_message;
	cli->sign_info.check_incoming_message = client_check_incoming_message;
	cli->sign_info.free_signing_context = simple_free_signing_context;

	return True;
}

/***********************************************************
 SMB signing - TEMP implementation - calculate a MAC to send.
************************************************************/

static void temp_sign_outgoing_message(char *outbuf, struct smb_sign_info *si)
{
	/* mark the packet as signed - BEFORE we sign it...*/
	mark_packet_signed(outbuf);

	/* I wonder what BSRSPYL stands for - but this is what MS 
	   actually sends! */
	memcpy(&outbuf[smb_ss_field], "BSRSPYL ", 8);
	return;
}

/***********************************************************
 SMB signing - TEMP implementation - check a MAC sent by server.
************************************************************/

static BOOL temp_check_incoming_message(const char *inbuf,
					struct smb_sign_info *si, BOOL foo)
{
	return True;
}

/***********************************************************
 SMB signing - TEMP implementation - free signing context
************************************************************/

static void temp_free_signing_context(struct smb_sign_info *si)
{
	return;
}

/***********************************************************
 SMB signing - NULL implementation - setup the MAC key.
************************************************************/

BOOL cli_null_set_signing(struct cli_state *cli)
{
	return null_set_signing(&cli->sign_info);
}

/***********************************************************
 SMB signing - temp implementation - setup the MAC key.
************************************************************/

BOOL cli_temp_set_signing(struct cli_state *cli)
{
	if (!cli_set_smb_signing_common(cli)) {
		return False;
	}

	cli->sign_info.signing_context = NULL;
	
	cli->sign_info.sign_outgoing_message = temp_sign_outgoing_message;
	cli->sign_info.check_incoming_message = temp_check_incoming_message;
	cli->sign_info.free_signing_context = temp_free_signing_context;

	return True;
}

void cli_free_signing_context(struct cli_state *cli)
{
	free_signing_context(&cli->sign_info);
}

/**
 * Sign a packet with the current mechanism
 */
 
void cli_calculate_sign_mac(struct cli_state *cli)
{
	cli->sign_info.sign_outgoing_message(cli->outbuf, &cli->sign_info);
}

/**
 * Check a packet with the current mechanism
 * @return False if we had an established signing connection
 *         which had a bad checksum, True otherwise.
 */
 
BOOL cli_check_sign_mac(struct cli_state *cli) 
{
	if (!cli->sign_info.check_incoming_message(cli->inbuf, &cli->sign_info, True)) {
		free_signing_context(&cli->sign_info);	
		return False;
	}
	return True;
}

/***********************************************************
 Enter trans/trans2/nttrans state.
************************************************************/

BOOL client_set_trans_sign_state_on(struct cli_state *cli, uint16 mid)
{
	struct smb_sign_info *si = &cli->sign_info;
	struct smb_basic_signing_context *data = (struct smb_basic_signing_context *)si->signing_context;

	if (!si->doing_signing) {
		return True;
	}

	if (!data) {
		return False;
	}

	if (!set_sequence_can_delete_flag(&data->outstanding_packet_list, mid, False)) {
		return False;
	}

	return True;
}

/***********************************************************
 Leave trans/trans2/nttrans state.
************************************************************/

BOOL client_set_trans_sign_state_off(struct cli_state *cli, uint16 mid)
{
	uint32 reply_seq_num;
	struct smb_sign_info *si = &cli->sign_info;
	struct smb_basic_signing_context *data = (struct smb_basic_signing_context *)si->signing_context;

	if (!si->doing_signing) {
		return True;
	}

	if (!data) {
		return False;
	}

	if (!set_sequence_can_delete_flag(&data->outstanding_packet_list, mid, True)) {
		return False;
	}

	/* Now delete the stored mid entry. */
	if (!get_sequence_for_reply(&data->outstanding_packet_list, mid, &reply_seq_num)) {
		return False;
	}

	return True;
}

/***********************************************************
 Is client signing on ?
************************************************************/

BOOL client_is_signing_on(struct cli_state *cli)
{
	struct smb_sign_info *si = &cli->sign_info;
	return si->doing_signing;
}

/***********************************************************
 SMB signing - Server implementation - send the MAC.
************************************************************/

static void srv_sign_outgoing_message(char *outbuf, struct smb_sign_info *si)
{
	unsigned char calc_md5_mac[16];
	struct smb_basic_signing_context *data =
		(struct smb_basic_signing_context *)si->signing_context;
	uint32 send_seq_number = data->send_seq_num-1;
	uint16 mid;

	if (!si->doing_signing) {
		return;
	}

	/* JRA Paranioa test - we should be able to get rid of this... */
	if (smb_len(outbuf) < (smb_ss_field + 8 - 4)) {
		DEBUG(1, ("srv_sign_outgoing_message: Logic error. Can't send signature on short packet! smb_len = %u\n",
					smb_len(outbuf) ));
		abort();
	}

	/* mark the packet as signed - BEFORE we sign it...*/
	mark_packet_signed(outbuf);

	mid = SVAL(outbuf, smb_mid);

	/* See if this is a reply for a deferred packet. */
	get_sequence_for_reply(&data->outstanding_packet_list, mid, &send_seq_number);

	simple_packet_signature(data, (const unsigned char *)outbuf, send_seq_number, calc_md5_mac);

	DEBUG(10, ("srv_sign_outgoing_message: seq %u: sent SMB signature of\n", (unsigned int)send_seq_number));
	dump_data(10, calc_md5_mac, 8);

	memcpy(&outbuf[smb_ss_field], calc_md5_mac, 8);

/*	cli->outbuf[smb_ss_field+2]=0; 
	Uncomment this to test if the remote client actually verifies signatures...*/
}

/***********************************************************
 SMB signing - Server implementation - check a MAC sent by server.
************************************************************/

static BOOL srv_check_incoming_message(const char *inbuf,
				       struct smb_sign_info *si,
				       BOOL must_be_ok)
{
	BOOL good;
	struct smb_basic_signing_context *data =
		(struct smb_basic_signing_context *)si->signing_context;
	uint32 reply_seq_number = data->send_seq_num;
	uint32 saved_seq;
	unsigned char calc_md5_mac[16];
	unsigned char *server_sent_mac;

	if (!si->doing_signing)
		return True;

	if (smb_len(inbuf) < (smb_ss_field + 8 - 4)) {
		DEBUG(1, ("srv_check_incoming_message: Can't check signature on short packet! smb_len = %u\n", smb_len(inbuf)));
		return False;
	}

	/* We always increment the sequence number. */
	data->send_seq_num += 2;

	saved_seq = reply_seq_number;
	simple_packet_signature(data, (const unsigned char *)inbuf, reply_seq_number, calc_md5_mac);

	server_sent_mac = (unsigned char *)&inbuf[smb_ss_field];
	good = (memcmp(server_sent_mac, calc_md5_mac, 8) == 0);
	
	if (!good) {

		if (saved_seq) {
			DEBUG(0, ("srv_check_incoming_message: BAD SIG: seq %u wanted SMB signature of\n",
					(unsigned int)saved_seq));
			dump_data(5, calc_md5_mac, 8);

			DEBUG(0, ("srv_check_incoming_message: BAD SIG: seq %u got SMB signature of\n",
						(unsigned int)reply_seq_number));
			dump_data(5, server_sent_mac, 8);
		}
		
#if 1 /* JRATEST */
		{
			int i;
			reply_seq_number -= 5;
			for (i = 0; i < 10; i++, reply_seq_number++) {
				simple_packet_signature(data, (const unsigned char *)inbuf, reply_seq_number, calc_md5_mac);
				if (memcmp(server_sent_mac, calc_md5_mac, 8) == 0) {
					DEBUG(0,("srv_check_incoming_message: out of seq. seq num %u matches. \
We were expecting seq %u\n", reply_seq_number, saved_seq ));
					break;
				}
			}
		}
#endif /* JRATEST */

	} else {
		DEBUG(10, ("srv_check_incoming_message: seq %u: (current is %u) got good SMB signature of\n", (unsigned int)reply_seq_number, (unsigned int)data->send_seq_num));
		dump_data(10, server_sent_mac, 8);
	}

	return (signing_good(inbuf, si, good, saved_seq, must_be_ok));
}

/***********************************************************
 SMB signing - server API's.
************************************************************/

static struct smb_sign_info srv_sign_info = {
	null_sign_outgoing_message,
	null_check_incoming_message,
	null_free_signing_context,
	NULL,
	False,
	False,
	False,
	False
};

/***********************************************************
 Turn signing off or on for oplock break code.
************************************************************/

BOOL srv_oplock_set_signing(BOOL onoff)
{
	BOOL ret = srv_sign_info.doing_signing;
	srv_sign_info.doing_signing = onoff;
	return ret;
}

/***********************************************************
 Called to validate an incoming packet from the client.
************************************************************/

BOOL srv_check_sign_mac(const char *inbuf, BOOL must_be_ok)
{
	/* Check if it's a session keepalive. */
	if(CVAL(inbuf,0) == SMBkeepalive) {
		return True;
	}

	return srv_sign_info.check_incoming_message(inbuf, &srv_sign_info, must_be_ok);
}

/***********************************************************
 Called to sign an outgoing packet to the client.
************************************************************/

void srv_calculate_sign_mac(char *outbuf)
{
	/* Check if it's a session keepalive. */
	if(CVAL(outbuf,0) == SMBkeepalive) {
		return;
	}

	srv_sign_info.sign_outgoing_message(outbuf, &srv_sign_info);
}

/***********************************************************
 Called by server to defer an outgoing packet.
************************************************************/

void srv_defer_sign_response(uint16 mid)
{
	struct smb_basic_signing_context *data;

	if (!srv_sign_info.doing_signing)
		return;

	data = (struct smb_basic_signing_context *)srv_sign_info.signing_context;

	if (!data)
		return;

	/*
	 * Ensure we only store this mid reply once...
	 */

	store_sequence_for_reply(&data->outstanding_packet_list, mid,
				 data->send_seq_num-1);
}

/***********************************************************
 Called to remove sequence records when a deferred packet is
 cancelled by mid. This should never find one....
************************************************************/

void srv_cancel_sign_response(uint16 mid)
{
	struct smb_basic_signing_context *data;
	uint32 dummy_seq;

	if (!srv_sign_info.doing_signing)
		return;

	data = (struct smb_basic_signing_context *)srv_sign_info.signing_context;

	if (!data)
		return;

	DEBUG(10,("srv_cancel_sign_response: for mid %u\n", (unsigned int)mid ));

	while (get_sequence_for_reply(&data->outstanding_packet_list, mid, &dummy_seq))
		;

	/* cancel doesn't send a reply so doesn't burn a sequence number. */
	data->send_seq_num -= 1;
}

/***********************************************************
 Called by server negprot when signing has been negotiated.
************************************************************/

void srv_set_signing_negotiated(void)
{
	srv_sign_info.allow_smb_signing = True;
	srv_sign_info.negotiated_smb_signing = True;
	if (lp_server_signing() == Required)
		srv_sign_info.mandatory_signing = True;

	srv_sign_info.sign_outgoing_message = temp_sign_outgoing_message;
	srv_sign_info.check_incoming_message = temp_check_incoming_message;
	srv_sign_info.free_signing_context = temp_free_signing_context;
}

/***********************************************************
 Returns whether signing is active. We can't use sendfile or raw
 reads/writes if it is.
************************************************************/

BOOL srv_is_signing_active(void)
{
	return srv_sign_info.doing_signing;
}


/***********************************************************
 Returns whether signing is negotiated. We can't use it unless it was
 in the negprot.  
************************************************************/

BOOL srv_is_signing_negotiated(void)
{
	return srv_sign_info.negotiated_smb_signing;
}

/***********************************************************
 Returns whether signing is actually happening
************************************************************/

BOOL srv_signing_started(void)
{
	struct smb_basic_signing_context *data;

	if (!srv_sign_info.doing_signing) {
		return False;
	}

	data = (struct smb_basic_signing_context *)srv_sign_info.signing_context;
	if (!data)
		return False;

	if (data->send_seq_num == 0) {
		return False;
	}

	return True;
}

/***********************************************************
 Turn on signing from this packet onwards. 
************************************************************/

void srv_set_signing(const DATA_BLOB user_session_key, const DATA_BLOB response)
{
	struct smb_basic_signing_context *data;

	if (!user_session_key.length)
		return;

	if (!srv_sign_info.negotiated_smb_signing && !srv_sign_info.mandatory_signing) {
		DEBUG(5,("srv_set_signing: signing negotiated = %u, mandatory_signing = %u. Not allowing smb signing.\n",
			(unsigned int)srv_sign_info.negotiated_smb_signing,
			(unsigned int)srv_sign_info.mandatory_signing ));
		return;
	}

	/* Once we've turned on, ignore any more sessionsetups. */
	if (srv_sign_info.doing_signing) {
		return;
	}
	
	if (srv_sign_info.free_signing_context)
		srv_sign_info.free_signing_context(&srv_sign_info);
	
	srv_sign_info.doing_signing = True;

	data = SMB_XMALLOC_P(struct smb_basic_signing_context);
	memset(data, '\0', sizeof(*data));

	srv_sign_info.signing_context = data;
	
	data->mac_key = data_blob(NULL, response.length + user_session_key.length);

	memcpy(&data->mac_key.data[0], user_session_key.data, user_session_key.length);
	if (response.length)
		memcpy(&data->mac_key.data[user_session_key.length],response.data, response.length);

	dump_data_pw("MAC ssession key is:\n", data->mac_key.data, data->mac_key.length);

	DEBUG(3,("srv_set_signing: turning on SMB signing: signing negotiated = %s, mandatory_signing = %s.\n",
				BOOLSTR(srv_sign_info.negotiated_smb_signing),
			 	BOOLSTR(srv_sign_info.mandatory_signing) ));

	/* Initialise the sequence number */
	data->send_seq_num = 0;

	/* Initialise the list of outstanding packets */
	data->outstanding_packet_list = NULL;

	srv_sign_info.sign_outgoing_message = srv_sign_outgoing_message;
	srv_sign_info.check_incoming_message = srv_check_incoming_message;
	srv_sign_info.free_signing_context = simple_free_signing_context;
}