summaryrefslogtreecommitdiff
path: root/security/selinux/ss/avtab.c
blob: c0417cf17feeee9bf5a94876553b02ac3119cb59 (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
/*
 * Implementation of the access vector table type.
 *
 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
 */

/* Updated: Frank Mayer <mayerf@tresys.com> and Karl MacMillan <kmacmillan@tresys.com>
 *
 *	Added conditional policy language extensions
 *
 * Copyright (C) 2003 Tresys Technology, LLC
 *	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, version 2.
 *
 * Updated: Yuichi Nakamura <ynakam@hitachisoft.jp>
 *	Tuned number of hash slots for avtab to reduce memory usage
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include "avtab.h"
#include "policydb.h"

static struct kmem_cache *avtab_node_cachep;
static struct kmem_cache *avtab_xperms_cachep;

/* Based on MurmurHash3, written by Austin Appleby and placed in the
 * public domain.
 */
static inline int avtab_hash(struct avtab_key *keyp, u32 mask)
{
	static const u32 c1 = 0xcc9e2d51;
	static const u32 c2 = 0x1b873593;
	static const u32 r1 = 15;
	static const u32 r2 = 13;
	static const u32 m  = 5;
	static const u32 n  = 0xe6546b64;

	u32 hash = 0;

#define mix(input) { \
	u32 v = input; \
	v *= c1; \
	v = (v << r1) | (v >> (32 - r1)); \
	v *= c2; \
	hash ^= v; \
	hash = (hash << r2) | (hash >> (32 - r2)); \
	hash = hash * m + n; \
}

	mix(keyp->target_class);
	mix(keyp->target_type);
	mix(keyp->source_type);

#undef mix

	hash ^= hash >> 16;
	hash *= 0x85ebca6b;
	hash ^= hash >> 13;
	hash *= 0xc2b2ae35;
	hash ^= hash >> 16;

	return hash & mask;
}

static struct avtab_node*
avtab_insert_node(struct avtab *h, int hvalue,
		  struct avtab_node *prev, struct avtab_node *cur,
		  struct avtab_key *key, struct avtab_datum *datum)
{
	struct avtab_node *newnode;
	struct avtab_extended_perms *xperms;
	newnode = kmem_cache_zalloc(avtab_node_cachep, GFP_KERNEL);
	if (newnode == NULL)
		return NULL;
	newnode->key = *key;

	if (key->specified & AVTAB_XPERMS) {
		xperms = kmem_cache_zalloc(avtab_xperms_cachep, GFP_KERNEL);
		if (xperms == NULL) {
			kmem_cache_free(avtab_node_cachep, newnode);
			return NULL;
		}
		*xperms = *(datum->u.xperms);
		newnode->datum.u.xperms = xperms;
	} else {
		newnode->datum.u.data = datum->u.data;
	}

	if (prev) {
		newnode->next = prev->next;
		prev->next = newnode;
	} else {
		newnode->next = flex_array_get_ptr(h->htable, hvalue);
		if (flex_array_put_ptr(h->htable, hvalue, newnode,
				       GFP_KERNEL|__GFP_ZERO)) {
			kmem_cache_free(avtab_node_cachep, newnode);
			return NULL;
		}
	}

	h->nel++;
	return newnode;
}

static int avtab_insert(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
{
	int hvalue;
	struct avtab_node *prev, *cur, *newnode;
	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

	if (!h || !h->htable)
		return -EINVAL;

	hvalue = avtab_hash(key, h->mask);
	for (prev = NULL, cur = flex_array_get_ptr(h->htable, hvalue);
	     cur;
	     prev = cur, cur = cur->next) {
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class == cur->key.target_class &&
		    (specified & cur->key.specified)) {
			/* extended perms may not be unique */
			if (specified & AVTAB_XPERMS)
				break;
			return -EEXIST;
		}
		if (key->source_type < cur->key.source_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type < cur->key.target_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class < cur->key.target_class)
			break;
	}

	newnode = avtab_insert_node(h, hvalue, prev, cur, key, datum);
	if (!newnode)
		return -ENOMEM;

	return 0;
}

/* Unlike avtab_insert(), this function allow multiple insertions of the same
 * key/specified mask into the table, as needed by the conditional avtab.
 * It also returns a pointer to the node inserted.
 */
struct avtab_node *
avtab_insert_nonunique(struct avtab *h, struct avtab_key *key, struct avtab_datum *datum)
{
	int hvalue;
	struct avtab_node *prev, *cur;
	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

	if (!h || !h->htable)
		return NULL;
	hvalue = avtab_hash(key, h->mask);
	for (prev = NULL, cur = flex_array_get_ptr(h->htable, hvalue);
	     cur;
	     prev = cur, cur = cur->next) {
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class == cur->key.target_class &&
		    (specified & cur->key.specified))
			break;
		if (key->source_type < cur->key.source_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type < cur->key.target_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class < cur->key.target_class)
			break;
	}
	return avtab_insert_node(h, hvalue, prev, cur, key, datum);
}

struct avtab_datum *avtab_search(struct avtab *h, struct avtab_key *key)
{
	int hvalue;
	struct avtab_node *cur;
	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

	if (!h || !h->htable)
		return NULL;

	hvalue = avtab_hash(key, h->mask);
	for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
	     cur = cur->next) {
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class == cur->key.target_class &&
		    (specified & cur->key.specified))
			return &cur->datum;

		if (key->source_type < cur->key.source_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type < cur->key.target_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class < cur->key.target_class)
			break;
	}

	return NULL;
}

/* This search function returns a node pointer, and can be used in
 * conjunction with avtab_search_next_node()
 */
struct avtab_node*
avtab_search_node(struct avtab *h, struct avtab_key *key)
{
	int hvalue;
	struct avtab_node *cur;
	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);

	if (!h || !h->htable)
		return NULL;

	hvalue = avtab_hash(key, h->mask);
	for (cur = flex_array_get_ptr(h->htable, hvalue); cur;
	     cur = cur->next) {
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class == cur->key.target_class &&
		    (specified & cur->key.specified))
			return cur;

		if (key->source_type < cur->key.source_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type < cur->key.target_type)
			break;
		if (key->source_type == cur->key.source_type &&
		    key->target_type == cur->key.target_type &&
		    key->target_class < cur->key.target_class)
			break;
	}
	return NULL;
}

struct avtab_node*
avtab_search_node_next(struct avtab_node *node, int specified)
{
	struct avtab_node *cur;

	if (!node)
		return NULL;

	specified &= ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
	for (cur = node->next; cur; cur = cur->next) {
		if (node->key.source_type == cur->key.source_type &&
		    node->key.target_type == cur->key.target_type &&
		    node->key.target_class == cur->key.target_class &&
		    (specified & cur->key.specified))
			return cur;

		if (node->key.source_type < cur->key.source_type)
			break;
		if (node->key.source_type == cur->key.source_type &&
		    node->key.target_type < cur->key.target_type)
			break;
		if (node->key.source_type == cur->key.source_type &&
		    node->key.target_type == cur->key.target_type &&
		    node->key.target_class < cur->key.target_class)
			break;
	}
	return NULL;
}

void avtab_destroy(struct avtab *h)
{
	int i;
	struct avtab_node *cur, *temp;

	if (!h || !h->htable)
		return;

	for (i = 0; i < h->nslot; i++) {
		cur = flex_array_get_ptr(h->htable, i);
		while (cur) {
			temp = cur;
			cur = cur->next;
			if (temp->key.specified & AVTAB_XPERMS)
				kmem_cache_free(avtab_xperms_cachep,
						temp->datum.u.xperms);
			kmem_cache_free(avtab_node_cachep, temp);
		}
	}
	flex_array_free(h->htable);
	h->htable = NULL;
	h->nslot = 0;
	h->mask = 0;
}

int avtab_init(struct avtab *h)
{
	h->htable = NULL;
	h->nel = 0;
	return 0;
}

int avtab_alloc(struct avtab *h, u32 nrules)
{
	u32 mask = 0;
	u32 shift = 0;
	u32 work = nrules;
	u32 nslot = 0;

	if (nrules == 0)
		goto avtab_alloc_out;

	while (work) {
		work  = work >> 1;
		shift++;
	}
	if (shift > 2)
		shift = shift - 2;
	nslot = 1 << shift;
	if (nslot > MAX_AVTAB_HASH_BUCKETS)
		nslot = MAX_AVTAB_HASH_BUCKETS;
	mask = nslot - 1;

	h->htable = flex_array_alloc(sizeof(struct avtab_node *), nslot,
				     GFP_KERNEL | __GFP_ZERO);
	if (!h->htable)
		return -ENOMEM;

 avtab_alloc_out:
	h->nel = 0;
	h->nslot = nslot;
	h->mask = mask;
	pr_debug("SELinux: %d avtab hash slots, %d rules.\n",
	       h->nslot, nrules);
	return 0;
}

void avtab_hash_eval(struct avtab *h, char *tag)
{
	int i, chain_len, slots_used, max_chain_len;
	unsigned long long chain2_len_sum;
	struct avtab_node *cur;

	slots_used = 0;
	max_chain_len = 0;
	chain2_len_sum = 0;
	for (i = 0; i < h->nslot; i++) {
		cur = flex_array_get_ptr(h->htable, i);
		if (cur) {
			slots_used++;
			chain_len = 0;
			while (cur) {
				chain_len++;
				cur = cur->next;
			}

			if (chain_len > max_chain_len)
				max_chain_len = chain_len;
			chain2_len_sum += chain_len * chain_len;
		}
	}

	pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, "
	       "longest chain length %d sum of chain length^2 %llu\n",
	       tag, h->nel, slots_used, h->nslot, max_chain_len,
	       chain2_len_sum);
}

static uint16_t spec_order[] = {
	AVTAB_ALLOWED,
	AVTAB_AUDITDENY,
	AVTAB_AUDITALLOW,
	AVTAB_TRANSITION,
	AVTAB_CHANGE,
	AVTAB_MEMBER,
	AVTAB_XPERMS_ALLOWED,
	AVTAB_XPERMS_AUDITALLOW,
	AVTAB_XPERMS_DONTAUDIT
};

int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
		    int (*insertf)(struct avtab *a, struct avtab_key *k,
				   struct avtab_datum *d, void *p),
		    void *p)
{
	__le16 buf16[4];
	u16 enabled;
	u32 items, items2, val, vers = pol->policyvers;
	struct avtab_key key;
	struct avtab_datum datum;
	struct avtab_extended_perms xperms;
	__le32 buf32[ARRAY_SIZE(xperms.perms.p)];
	int i, rc;
	unsigned set;

	memset(&key, 0, sizeof(struct avtab_key));
	memset(&datum, 0, sizeof(struct avtab_datum));

	if (vers < POLICYDB_VERSION_AVTAB) {
		rc = next_entry(buf32, fp, sizeof(u32));
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		items2 = le32_to_cpu(buf32[0]);
		if (items2 > ARRAY_SIZE(buf32)) {
			pr_err("SELinux: avtab: entry overflow\n");
			return -EINVAL;

		}
		rc = next_entry(buf32, fp, sizeof(u32)*items2);
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		items = 0;

		val = le32_to_cpu(buf32[items++]);
		key.source_type = (u16)val;
		if (key.source_type != val) {
			pr_err("SELinux: avtab: truncated source type\n");
			return -EINVAL;
		}
		val = le32_to_cpu(buf32[items++]);
		key.target_type = (u16)val;
		if (key.target_type != val) {
			pr_err("SELinux: avtab: truncated target type\n");
			return -EINVAL;
		}
		val = le32_to_cpu(buf32[items++]);
		key.target_class = (u16)val;
		if (key.target_class != val) {
			pr_err("SELinux: avtab: truncated target class\n");
			return -EINVAL;
		}

		val = le32_to_cpu(buf32[items++]);
		enabled = (val & AVTAB_ENABLED_OLD) ? AVTAB_ENABLED : 0;

		if (!(val & (AVTAB_AV | AVTAB_TYPE))) {
			pr_err("SELinux: avtab: null entry\n");
			return -EINVAL;
		}
		if ((val & AVTAB_AV) &&
		    (val & AVTAB_TYPE)) {
			pr_err("SELinux: avtab: entry has both access vectors and types\n");
			return -EINVAL;
		}
		if (val & AVTAB_XPERMS) {
			pr_err("SELinux: avtab: entry has extended permissions\n");
			return -EINVAL;
		}

		for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
			if (val & spec_order[i]) {
				key.specified = spec_order[i] | enabled;
				datum.u.data = le32_to_cpu(buf32[items++]);
				rc = insertf(a, &key, &datum, p);
				if (rc)
					return rc;
			}
		}

		if (items != items2) {
			pr_err("SELinux: avtab: entry only had %d items, expected %d\n",
			       items2, items);
			return -EINVAL;
		}
		return 0;
	}

	rc = next_entry(buf16, fp, sizeof(u16)*4);
	if (rc) {
		pr_err("SELinux: avtab: truncated entry\n");
		return rc;
	}

	items = 0;
	key.source_type = le16_to_cpu(buf16[items++]);
	key.target_type = le16_to_cpu(buf16[items++]);
	key.target_class = le16_to_cpu(buf16[items++]);
	key.specified = le16_to_cpu(buf16[items++]);

	if (!policydb_type_isvalid(pol, key.source_type) ||
	    !policydb_type_isvalid(pol, key.target_type) ||
	    !policydb_class_isvalid(pol, key.target_class)) {
		pr_err("SELinux: avtab: invalid type or class\n");
		return -EINVAL;
	}

	set = 0;
	for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
		if (key.specified & spec_order[i])
			set++;
	}
	if (!set || set > 1) {
		pr_err("SELinux:  avtab:  more than one specifier\n");
		return -EINVAL;
	}

	if ((vers < POLICYDB_VERSION_XPERMS_IOCTL) &&
			(key.specified & AVTAB_XPERMS)) {
		pr_err("SELinux:  avtab:  policy version %u does not "
				"support extended permissions rules and one "
				"was specified\n", vers);
		return -EINVAL;
	} else if (key.specified & AVTAB_XPERMS) {
		memset(&xperms, 0, sizeof(struct avtab_extended_perms));
		rc = next_entry(&xperms.specified, fp, sizeof(u8));
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		rc = next_entry(&xperms.driver, fp, sizeof(u8));
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		rc = next_entry(buf32, fp, sizeof(u32)*ARRAY_SIZE(xperms.perms.p));
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		for (i = 0; i < ARRAY_SIZE(xperms.perms.p); i++)
			xperms.perms.p[i] = le32_to_cpu(buf32[i]);
		datum.u.xperms = &xperms;
	} else {
		rc = next_entry(buf32, fp, sizeof(u32));
		if (rc) {
			pr_err("SELinux: avtab: truncated entry\n");
			return rc;
		}
		datum.u.data = le32_to_cpu(*buf32);
	}
	if ((key.specified & AVTAB_TYPE) &&
	    !policydb_type_isvalid(pol, datum.u.data)) {
		pr_err("SELinux: avtab: invalid type\n");
		return -EINVAL;
	}
	return insertf(a, &key, &datum, p);
}

static int avtab_insertf(struct avtab *a, struct avtab_key *k,
			 struct avtab_datum *d, void *p)
{
	return avtab_insert(a, k, d);
}

int avtab_read(struct avtab *a, void *fp, struct policydb *pol)
{
	int rc;
	__le32 buf[1];
	u32 nel, i;


	rc = next_entry(buf, fp, sizeof(u32));
	if (rc < 0) {
		pr_err("SELinux: avtab: truncated table\n");
		goto bad;
	}
	nel = le32_to_cpu(buf[0]);
	if (!nel) {
		pr_err("SELinux: avtab: table is empty\n");
		rc = -EINVAL;
		goto bad;
	}

	rc = avtab_alloc(a, nel);
	if (rc)
		goto bad;

	for (i = 0; i < nel; i++) {
		rc = avtab_read_item(a, fp, pol, avtab_insertf, NULL);
		if (rc) {
			if (rc == -ENOMEM)
				pr_err("SELinux: avtab: out of memory\n");
			else if (rc == -EEXIST)
				pr_err("SELinux: avtab: duplicate entry\n");

			goto bad;
		}
	}

	rc = 0;
out:
	return rc;

bad:
	avtab_destroy(a);
	goto out;
}

int avtab_write_item(struct policydb *p, struct avtab_node *cur, void *fp)
{
	__le16 buf16[4];
	__le32 buf32[ARRAY_SIZE(cur->datum.u.xperms->perms.p)];
	int rc;
	unsigned int i;

	buf16[0] = cpu_to_le16(cur->key.source_type);
	buf16[1] = cpu_to_le16(cur->key.target_type);
	buf16[2] = cpu_to_le16(cur->key.target_class);
	buf16[3] = cpu_to_le16(cur->key.specified);
	rc = put_entry(buf16, sizeof(u16), 4, fp);
	if (rc)
		return rc;

	if (cur->key.specified & AVTAB_XPERMS) {
		rc = put_entry(&cur->datum.u.xperms->specified, sizeof(u8), 1, fp);
		if (rc)
			return rc;
		rc = put_entry(&cur->datum.u.xperms->driver, sizeof(u8), 1, fp);
		if (rc)
			return rc;
		for (i = 0; i < ARRAY_SIZE(cur->datum.u.xperms->perms.p); i++)
			buf32[i] = cpu_to_le32(cur->datum.u.xperms->perms.p[i]);
		rc = put_entry(buf32, sizeof(u32),
				ARRAY_SIZE(cur->datum.u.xperms->perms.p), fp);
	} else {
		buf32[0] = cpu_to_le32(cur->datum.u.data);
		rc = put_entry(buf32, sizeof(u32), 1, fp);
	}
	if (rc)
		return rc;
	return 0;
}

int avtab_write(struct policydb *p, struct avtab *a, void *fp)
{
	unsigned int i;
	int rc = 0;
	struct avtab_node *cur;
	__le32 buf[1];

	buf[0] = cpu_to_le32(a->nel);
	rc = put_entry(buf, sizeof(u32), 1, fp);
	if (rc)
		return rc;

	for (i = 0; i < a->nslot; i++) {
		for (cur = flex_array_get_ptr(a->htable, i); cur;
		     cur = cur->next) {
			rc = avtab_write_item(p, cur, fp);
			if (rc)
				return rc;
		}
	}

	return rc;
}

void __init avtab_cache_init(void)
{
	avtab_node_cachep = kmem_cache_create("avtab_node",
					      sizeof(struct avtab_node),
					      0, SLAB_PANIC, NULL);
	avtab_xperms_cachep = kmem_cache_create("avtab_extended_perms",
						sizeof(struct avtab_extended_perms),
						0, SLAB_PANIC, NULL);
}