aboutsummaryrefslogtreecommitdiffstats
path: root/fs/cifs/asn1.c
blob: 20692fbfdb244ffb3d5b7acc5e5d84da00d3f7ba (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
/*
 * The ASB.1/BER parsing code is derived from ip_nat_snmp_basic.c which was in
 * turn derived from the gxsnmp package by Gregory McLean & Jochen Friedrich
 *
 * Copyright (c) 2000 RP Internet (www.rpi.net.au).
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifs_debug.h"
#include "cifsproto.h"

/*****************************************************************************
 *
 * Basic ASN.1 decoding routines (gxsnmp author Dirk Wisse)
 *
 *****************************************************************************/

/* Class */
#define ASN1_UNI	0	/* Universal */
#define ASN1_APL	1	/* Application */
#define ASN1_CTX	2	/* Context */
#define ASN1_PRV	3	/* Private */

/* Tag */
#define ASN1_EOC	0	/* End Of Contents or N/A */
#define ASN1_BOL	1	/* Boolean */
#define ASN1_INT	2	/* Integer */
#define ASN1_BTS	3	/* Bit String */
#define ASN1_OTS	4	/* Octet String */
#define ASN1_NUL	5	/* Null */
#define ASN1_OJI	6	/* Object Identifier  */
#define ASN1_OJD	7	/* Object Description */
#define ASN1_EXT	8	/* External */
#define ASN1_ENUM	10	/* Enumerated */
#define ASN1_SEQ	16	/* Sequence */
#define ASN1_SET	17	/* Set */
#define ASN1_NUMSTR	18	/* Numerical String */
#define ASN1_PRNSTR	19	/* Printable String */
#define ASN1_TEXSTR	20	/* Teletext String */
#define ASN1_VIDSTR	21	/* Video String */
#define ASN1_IA5STR	22	/* IA5 String */
#define ASN1_UNITIM	23	/* Universal Time */
#define ASN1_GENTIM	24	/* General Time */
#define ASN1_GRASTR	25	/* Graphical String */
#define ASN1_VISSTR	26	/* Visible String */
#define ASN1_GENSTR	27	/* General String */

/* Primitive / Constructed methods*/
#define ASN1_PRI	0	/* Primitive */
#define ASN1_CON	1	/* Constructed */

/*
 * Error codes.
 */
#define ASN1_ERR_NOERROR		0
#define ASN1_ERR_DEC_EMPTY		2
#define ASN1_ERR_DEC_EOC_MISMATCH	3
#define ASN1_ERR_DEC_LENGTH_MISMATCH	4
#define ASN1_ERR_DEC_BADVALUE		5

#define SPNEGO_OID_LEN 7
#define NTLMSSP_OID_LEN  10
#define KRB5_OID_LEN  7
#define KRB5U2U_OID_LEN  8
#define MSKRB5_OID_LEN  7
static unsigned long SPNEGO_OID[7] = { 1, 3, 6, 1, 5, 5, 2 };
static unsigned long NTLMSSP_OID[10] = { 1, 3, 6, 1, 4, 1, 311, 2, 2, 10 };
static unsigned long KRB5_OID[7] = { 1, 2, 840, 113554, 1, 2, 2 };
static unsigned long KRB5U2U_OID[8] = { 1, 2, 840, 113554, 1, 2, 2, 3 };
static unsigned long MSKRB5_OID[7] = { 1, 2, 840, 48018, 1, 2, 2 };

/*
 * ASN.1 context.
 */
struct asn1_ctx {
	int error;		/* Error condition */
	unsigned char *pointer;	/* Octet just to be decoded */
	unsigned char *begin;	/* First octet */
	unsigned char *end;	/* Octet after last octet */
};

/*
 * Octet string (not null terminated)
 */
struct asn1_octstr {
	unsigned char *data;
	unsigned int len;
};

static void
asn1_open(struct asn1_ctx *ctx, unsigned char *buf, unsigned int len)
{
	ctx->begin = buf;
	ctx->end = buf + len;
	ctx->pointer = buf;
	ctx->error = ASN1_ERR_NOERROR;
}

static unsigned char
asn1_octet_decode(struct asn1_ctx *ctx, unsigned char *ch)
{
	if (ctx->pointer >= ctx->end) {
		ctx->error = ASN1_ERR_DEC_EMPTY;
		return 0;
	}
	*ch = *(ctx->pointer)++;
	return 1;
}

#if 0 /* will be needed later by spnego decoding/encoding of ntlmssp */
static unsigned char
asn1_enum_decode(struct asn1_ctx *ctx, __le32 *val)
{
	unsigned char ch;

	if (ctx->pointer >= ctx->end) {
		ctx->error = ASN1_ERR_DEC_EMPTY;
		return 0;
	}

	ch = *(ctx->pointer)++; /* ch has 0xa, ptr points to lenght octet */
	if ((ch) == ASN1_ENUM)  /* if ch value is ENUM, 0xa */
		*val = *(++(ctx->pointer)); /* value has enum value */
	else
		return 0;

	ctx->pointer++;
	return 1;
}
#endif

static unsigned char
asn1_tag_decode(struct asn1_ctx *ctx, unsigned int *tag)
{
	unsigned char ch;

	*tag = 0;

	do {
		if (!asn1_octet_decode(ctx, &ch))
			return 0;
		*tag <<= 7;
		*tag |= ch & 0x7F;
	} while ((ch & 0x80) == 0x80);
	return 1;
}

static unsigned char
asn1_id_decode(struct asn1_ctx *ctx,
	       unsigned int *cls, unsigned int *con, unsigned int *tag)
{
	unsigned char ch;

	if (!asn1_octet_decode(ctx, &ch))
		return 0;

	*cls = (ch & 0xC0) >> 6;
	*con = (ch & 0x20) >> 5;
	*tag = (ch & 0x1F);

	if (*tag == 0x1F) {
		if (!asn1_tag_decode(ctx, tag))
			return 0;
	}
	return 1;
}

static unsigned char
asn1_length_decode(struct asn1_ctx *ctx, unsigned int *def, unsigned int *len)
{
	unsigned char ch, cnt;

	if (!asn1_octet_decode(ctx, &ch))
		return 0;

	if (ch == 0x80)
		*def = 0;
	else {
		*def = 1;

		if (ch < 0x80)
			*len = ch;
		else {
			cnt = (unsigned char) (ch & 0x7F);
			*len = 0;

			while (cnt > 0) {
				if (!asn1_octet_decode(ctx, &ch))
					return 0;
				*len <<= 8;
				*len |= ch;
				cnt--;
			}
		}
	}

	/* don't trust len bigger than ctx buffer */
	if (*len > ctx->end - ctx->pointer)
		return 0;

	return 1;
}

static unsigned char
asn1_header_decode(struct asn1_ctx *ctx,
		   unsigned char **eoc,
		   unsigned int *cls, unsigned int *con, unsigned int *tag)
{
	unsigned int def = 0;
	unsigned int len = 0;

	if (!asn1_id_decode(ctx, cls, con, tag))
		return 0;

	if (!asn1_length_decode(ctx, &def, &len))
		return 0;

	/* primitive shall be definite, indefinite shall be constructed */
	if (*con == ASN1_PRI && !def)
		return 0;

	if (def)
		*eoc = ctx->pointer + len;
	else
		*eoc = NULL;
	return 1;
}

static unsigned char
asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
{
	unsigned char ch;

	if (eoc == NULL) {
		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		if (ch != 0x00) {
			ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
			return 0;
		}

		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		if (ch != 0x00) {
			ctx->error = ASN1_ERR_DEC_EOC_MISMATCH;
			return 0;
		}
		return 1;
	} else {
		if (ctx->pointer != eoc) {
			ctx->error = ASN1_ERR_DEC_LENGTH_MISMATCH;
			return 0;
		}
		return 1;
	}
}

/* static unsigned char asn1_null_decode(struct asn1_ctx *ctx,
				      unsigned char *eoc)
{
	ctx->pointer = eoc;
	return 1;
}

static unsigned char asn1_long_decode(struct asn1_ctx *ctx,
				      unsigned char *eoc, long *integer)
{
	unsigned char ch;
	unsigned int len;

	if (!asn1_octet_decode(ctx, &ch))
		return 0;

	*integer = (signed char) ch;
	len = 1;

	while (ctx->pointer < eoc) {
		if (++len > sizeof(long)) {
			ctx->error = ASN1_ERR_DEC_BADVALUE;
			return 0;
		}

		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		*integer <<= 8;
		*integer |= ch;
	}
	return 1;
}

static unsigned char asn1_uint_decode(struct asn1_ctx *ctx,
				      unsigned char *eoc,
				      unsigned int *integer)
{
	unsigned char ch;
	unsigned int len;

	if (!asn1_octet_decode(ctx, &ch))
		return 0;

	*integer = ch;
	if (ch == 0)
		len = 0;
	else
		len = 1;

	while (ctx->pointer < eoc) {
		if (++len > sizeof(unsigned int)) {
			ctx->error = ASN1_ERR_DEC_BADVALUE;
			return 0;
		}

		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		*integer <<= 8;
		*integer |= ch;
	}
	return 1;
}

static unsigned char asn1_ulong_decode(struct asn1_ctx *ctx,
				       unsigned char *eoc,
				       unsigned long *integer)
{
	unsigned char ch;
	unsigned int len;

	if (!asn1_octet_decode(ctx, &ch))
		return 0;

	*integer = ch;
	if (ch == 0)
		len = 0;
	else
		len = 1;

	while (ctx->pointer < eoc) {
		if (++len > sizeof(unsigned long)) {
			ctx->error = ASN1_ERR_DEC_BADVALUE;
			return 0;
		}

		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		*integer <<= 8;
		*integer |= ch;
	}
	return 1;
}

static unsigned char
asn1_octets_decode(struct asn1_ctx *ctx,
		   unsigned char *eoc,
		   unsigned char **octets, unsigned int *len)
{
	unsigned char *ptr;

	*len = 0;

	*octets = kmalloc(eoc - ctx->pointer, GFP_ATOMIC);
	if (*octets == NULL) {
		return 0;
	}

	ptr = *octets;
	while (ctx->pointer < eoc) {
		if (!asn1_octet_decode(ctx, (unsigned char *) ptr++)) {
			kfree(*octets);
			*octets = NULL;
			return 0;
		}
		(*len)++;
	}
	return 1;
} */

static unsigned char
asn1_subid_decode(struct asn1_ctx *ctx, unsigned long *subid)
{
	unsigned char ch;

	*subid = 0;

	do {
		if (!asn1_octet_decode(ctx, &ch))
			return 0;

		*subid <<= 7;
		*subid |= ch & 0x7F;
	} while ((ch & 0x80) == 0x80);
	return 1;
}

static int
asn1_oid_decode(struct asn1_ctx *ctx,
		unsigned char *eoc, unsigned long **oid, unsigned int *len)
{
	unsigned long subid;
	unsigned int size;
	unsigned long *optr;

	size = eoc - ctx->pointer + 1;

	/* first subid actually encodes first two subids */
	if (size < 2 || size > UINT_MAX/sizeof(unsigned long))
		return 0;

	*oid = kmalloc(size * sizeof(unsigned long), GFP_ATOMIC);
	if (*oid == NULL)
		return 0;

	optr = *oid;

	if (!asn1_subid_decode(ctx, &subid)) {
		kfree(*oid);
		*oid = NULL;
		return 0;
	}

	if (subid < 40) {
		optr[0] = 0;
		optr[1] = subid;
	} else if (subid < 80) {
		optr[0] = 1;
		optr[1] = subid - 40;
	} else {
		optr[0] = 2;
		optr[1] = subid - 80;
	}

	*len = 2;
	optr += 2;

	while (ctx->pointer < eoc) {
		if (++(*len) > size) {
			ctx->error = ASN1_ERR_DEC_BADVALUE;
			kfree(*oid);
			*oid = NULL;
			return 0;
		}

		if (!asn1_subid_decode(ctx, optr++)) {
			kfree(*oid);
			*oid = NULL;
			return 0;
		}
	}
	return 1;
}

static int
compare_oid(unsigned long *oid1, unsigned int oid1len,
	    unsigned long *oid2, unsigned int oid2len)
{
	unsigned int i;

	if (oid1len != oid2len)
		return 0;
	else {
		for (i = 0; i < oid1len; i++) {
			if (oid1[i] != oid2[i])
				return 0;
		}
		return 1;
	}
}

	/* BB check for endian conversion issues here */

int
decode_negTokenInit(unsigned char *security_blob, int length,
		    enum securityEnum *secType)
{
	struct asn1_ctx ctx;
	unsigned char *end;
	unsigned char *sequence_end;
	unsigned long *oid = NULL;
	unsigned int cls, con, tag, oidlen, rc;
	bool use_ntlmssp = false;
	bool use_kerberos = false;
	bool use_kerberosu2u = false;
	bool use_mskerberos = false;

	/* cifs_dump_mem(" Received SecBlob ", security_blob, length); */

	asn1_open(&ctx, security_blob, length);

	/* GSSAPI header */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding negTokenInit header"));
		return 0;
	} else if ((cls != ASN1_APL) || (con != ASN1_CON)
		   || (tag != ASN1_EOC)) {
		cFYI(1, ("cls = %d con = %d tag = %d", cls, con, tag));
		return 0;
	}

	/* Check for SPNEGO OID -- remember to free obj->oid */
	rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
	if (rc) {
		if ((tag == ASN1_OJI) && (con == ASN1_PRI) &&
		    (cls == ASN1_UNI)) {
			rc = asn1_oid_decode(&ctx, end, &oid, &oidlen);
			if (rc) {
				rc = compare_oid(oid, oidlen, SPNEGO_OID,
						 SPNEGO_OID_LEN);
				kfree(oid);
			}
		} else
			rc = 0;
	}

	/* SPNEGO OID not present or garbled -- bail out */
	if (!rc) {
		cFYI(1, ("Error decoding negTokenInit header"));
		return 0;
	}

	/* SPNEGO */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding negTokenInit"));
		return 0;
	} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
		   || (tag != ASN1_EOC)) {
		cFYI(1,
		     ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
		      cls, con, tag, end, *end));
		return 0;
	}

	/* negTokenInit */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding negTokenInit"));
		return 0;
	} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
		   || (tag != ASN1_SEQ)) {
		cFYI(1,
		     ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
		      cls, con, tag, end, *end));
		return 0;
	}

	/* sequence */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding 2nd part of negTokenInit"));
		return 0;
	} else if ((cls != ASN1_CTX) || (con != ASN1_CON)
		   || (tag != ASN1_EOC)) {
		cFYI(1,
		     ("cls = %d con = %d tag = %d end = %p (%d) exit 0",
		      cls, con, tag, end, *end));
		return 0;
	}

	/* sequence of */
	if (asn1_header_decode
	    (&ctx, &sequence_end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding 2nd part of negTokenInit"));
		return 0;
	} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
		   || (tag != ASN1_SEQ)) {
		cFYI(1,
		     ("cls = %d con = %d tag = %d end = %p (%d) exit 1",
		      cls, con, tag, end, *end));
		return 0;
	}

	/* list of security mechanisms */
	while (!asn1_eoc_decode(&ctx, sequence_end)) {
		rc = asn1_header_decode(&ctx, &end, &cls, &con, &tag);
		if (!rc) {
			cFYI(1,
			     ("Error decoding negTokenInit hdr exit2"));
			return 0;
		}
		if ((tag == ASN1_OJI) && (con == ASN1_PRI)) {
			if (asn1_oid_decode(&ctx, end, &oid, &oidlen)) {

				cFYI(1, ("OID len = %d oid = 0x%lx 0x%lx "
					 "0x%lx 0x%lx", oidlen, *oid,
					 *(oid + 1), *(oid + 2), *(oid + 3)));

				if (compare_oid(oid, oidlen, MSKRB5_OID,
						MSKRB5_OID_LEN) &&
						!use_mskerberos)
					use_mskerberos = true;
				else if (compare_oid(oid, oidlen, KRB5U2U_OID,
						     KRB5U2U_OID_LEN) &&
						     !use_kerberosu2u)
					use_kerberosu2u = true;
				else if (compare_oid(oid, oidlen, KRB5_OID,
						     KRB5_OID_LEN) &&
						     !use_kerberos)
					use_kerberos = true;
				else if (compare_oid(oid, oidlen, NTLMSSP_OID,
						     NTLMSSP_OID_LEN))
					use_ntlmssp = true;

				kfree(oid);
			}
		} else {
			cFYI(1, ("Should be an oid what is going on?"));
		}
	}

	/* mechlistMIC */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		/* Check if we have reached the end of the blob, but with
		   no mechListMic (e.g. NTLMSSP instead of KRB5) */
		if (ctx.error == ASN1_ERR_DEC_EMPTY)
			goto decode_negtoken_exit;
		cFYI(1, ("Error decoding last part negTokenInit exit3"));
		return 0;
	} else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
		/* tag = 3 indicating mechListMIC */
		cFYI(1, ("Exit 4 cls = %d con = %d tag = %d end = %p (%d)",
			 cls, con, tag, end, *end));
		return 0;
	}

	/* sequence */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding last part negTokenInit exit5"));
		return 0;
	} else if ((cls != ASN1_UNI) || (con != ASN1_CON)
		   || (tag != ASN1_SEQ)) {
		cFYI(1, ("cls = %d con = %d tag = %d end = %p (%d)",
			cls, con, tag, end, *end));
	}

	/* sequence of */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding last part negTokenInit exit 7"));
		return 0;
	} else if ((cls != ASN1_CTX) || (con != ASN1_CON)) {
		cFYI(1, ("Exit 8 cls = %d con = %d tag = %d end = %p (%d)",
			 cls, con, tag, end, *end));
		return 0;
	}

	/* general string */
	if (asn1_header_decode(&ctx, &end, &cls, &con, &tag) == 0) {
		cFYI(1, ("Error decoding last part negTokenInit exit9"));
		return 0;
	} else if ((cls != ASN1_UNI) || (con != ASN1_PRI)
		   || (tag != ASN1_GENSTR)) {
		cFYI(1, ("Exit10 cls = %d con = %d tag = %d end = %p (%d)",
			 cls, con, tag, end, *end));
		return 0;
	}
	cFYI(1, ("Need to call asn1_octets_decode() function for %s",
		 ctx.pointer));	/* is this UTF-8 or ASCII? */
decode_negtoken_exit:
	if (use_kerberos)
		*secType = Kerberos;
	else if (use_mskerberos)
		*secType = MSKerberos;
	else if (use_ntlmssp)
		*secType = RawNTLMSSP;

	return 1;
}