aboutsummaryrefslogtreecommitdiffstats
path: root/security/selinux/ss/conditional.c
blob: daf2880074607fd535080ed6a08bebd3a36a3082 (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
/* Authors: Karl MacMillan <kmacmillan@tresys.com>
 *          Frank Mayer <mayerf@tresys.com>
 *
 * Copyright (C) 2003 - 2004 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.
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <asm/semaphore.h>
#include <linux/slab.h>

#include "security.h"
#include "conditional.h"

/*
 * cond_evaluate_expr evaluates a conditional expr
 * in reverse polish notation. It returns true (1), false (0),
 * or undefined (-1). Undefined occurs when the expression
 * exceeds the stack depth of COND_EXPR_MAXDEPTH.
 */
static int cond_evaluate_expr(struct policydb *p, struct cond_expr *expr)
{

	struct cond_expr *cur;
	int s[COND_EXPR_MAXDEPTH];
	int sp = -1;

	for (cur = expr; cur != NULL; cur = cur->next) {
		switch (cur->expr_type) {
		case COND_BOOL:
			if (sp == (COND_EXPR_MAXDEPTH - 1))
				return -1;
			sp++;
			s[sp] = p->bool_val_to_struct[cur->bool - 1]->state;
			break;
		case COND_NOT:
			if (sp < 0)
				return -1;
			s[sp] = !s[sp];
			break;
		case COND_OR:
			if (sp < 1)
				return -1;
			sp--;
			s[sp] |= s[sp + 1];
			break;
		case COND_AND:
			if (sp < 1)
				return -1;
			sp--;
			s[sp] &= s[sp + 1];
			break;
		case COND_XOR:
			if (sp < 1)
				return -1;
			sp--;
			s[sp] ^= s[sp + 1];
			break;
		case COND_EQ:
			if (sp < 1)
				return -1;
			sp--;
			s[sp] = (s[sp] == s[sp + 1]);
			break;
		case COND_NEQ:
			if (sp < 1)
				return -1;
			sp--;
			s[sp] = (s[sp] != s[sp + 1]);
			break;
		default:
			return -1;
		}
	}
	return s[0];
}

/*
 * evaluate_cond_node evaluates the conditional stored in
 * a struct cond_node and if the result is different than the
 * current state of the node it sets the rules in the true/false
 * list appropriately. If the result of the expression is undefined
 * all of the rules are disabled for safety.
 */
int evaluate_cond_node(struct policydb *p, struct cond_node *node)
{
	int new_state;
	struct cond_av_list* cur;

	new_state = cond_evaluate_expr(p, node->expr);
	if (new_state != node->cur_state) {
		node->cur_state = new_state;
		if (new_state == -1)
			printk(KERN_ERR "security: expression result was undefined - disabling all rules.\n");
		/* turn the rules on or off */
		for (cur = node->true_list; cur != NULL; cur = cur->next) {
			if (new_state <= 0) {
				cur->node->key.specified &= ~AVTAB_ENABLED;
			} else {
				cur->node->key.specified |= AVTAB_ENABLED;
			}
		}

		for (cur = node->false_list; cur != NULL; cur = cur->next) {
			/* -1 or 1 */
			if (new_state) {
				cur->node->key.specified &= ~AVTAB_ENABLED;
			} else {
				cur->node->key.specified |= AVTAB_ENABLED;
			}
		}
	}
	return 0;
}

int cond_policydb_init(struct policydb *p)
{
	p->bool_val_to_struct = NULL;
	p->cond_list = NULL;
	if (avtab_init(&p->te_cond_avtab))
		return -1;

	return 0;
}

static void cond_av_list_destroy(struct cond_av_list *list)
{
	struct cond_av_list *cur, *next;
	for (cur = list; cur != NULL; cur = next) {
		next = cur->next;
		/* the avtab_ptr_t node is destroy by the avtab */
		kfree(cur);
	}
}

static void cond_node_destroy(struct cond_node *node)
{
	struct cond_expr *cur_expr, *next_expr;

	for (cur_expr = node->expr; cur_expr != NULL; cur_expr = next_expr) {
		next_expr = cur_expr->next;
		kfree(cur_expr);
	}
	cond_av_list_destroy(node->true_list);
	cond_av_list_destroy(node->false_list);
	kfree(node);
}

static void cond_list_destroy(struct cond_node *list)
{
	struct cond_node *next, *cur;

	if (list == NULL)
		return;

	for (cur = list; cur != NULL; cur = next) {
		next = cur->next;
		cond_node_destroy(cur);
	}
}

void cond_policydb_destroy(struct policydb *p)
{
	kfree(p->bool_val_to_struct);
	avtab_destroy(&p->te_cond_avtab);
	cond_list_destroy(p->cond_list);
}

int cond_init_bool_indexes(struct policydb *p)
{
	kfree(p->bool_val_to_struct);
	p->bool_val_to_struct = (struct cond_bool_datum**)
		kmalloc(p->p_bools.nprim * sizeof(struct cond_bool_datum*), GFP_KERNEL);
	if (!p->bool_val_to_struct)
		return -1;
	return 0;
}

int cond_destroy_bool(void *key, void *datum, void *p)
{
	kfree(key);
	kfree(datum);
	return 0;
}

int cond_index_bool(void *key, void *datum, void *datap)
{
	struct policydb *p;
	struct cond_bool_datum *booldatum;

	booldatum = datum;
	p = datap;

	if (!booldatum->value || booldatum->value > p->p_bools.nprim)
		return -EINVAL;

	p->p_bool_val_to_name[booldatum->value - 1] = key;
	p->bool_val_to_struct[booldatum->value -1] = booldatum;

	return 0;
}

static int bool_isvalid(struct cond_bool_datum *b)
{
	if (!(b->state == 0 || b->state == 1))
		return 0;
	return 1;
}

int cond_read_bool(struct policydb *p, struct hashtab *h, void *fp)
{
	char *key = NULL;
	struct cond_bool_datum *booldatum;
	__le32 buf[3];
	u32 len;
	int rc;

	booldatum = kmalloc(sizeof(struct cond_bool_datum), GFP_KERNEL);
	if (!booldatum)
		return -1;
	memset(booldatum, 0, sizeof(struct cond_bool_datum));

	rc = next_entry(buf, fp, sizeof buf);
	if (rc < 0)
		goto err;

	booldatum->value = le32_to_cpu(buf[0]);
	booldatum->state = le32_to_cpu(buf[1]);

	if (!bool_isvalid(booldatum))
		goto err;

	len = le32_to_cpu(buf[2]);

	key = kmalloc(len + 1, GFP_KERNEL);
	if (!key)
		goto err;
	rc = next_entry(key, fp, len);
	if (rc < 0)
		goto err;
	key[len] = 0;
	if (hashtab_insert(h, key, booldatum))
		goto err;

	return 0;
err:
	cond_destroy_bool(key, booldatum, NULL);
	return -1;
}

struct cond_insertf_data
{
	struct policydb *p;
	struct cond_av_list *other;
	struct cond_av_list *head;
	struct cond_av_list *tail;
};

static int cond_insertf(struct avtab *a, struct avtab_key *k, struct avtab_datum *d, void *ptr)
{
	struct cond_insertf_data *data = ptr;
	struct policydb *p = data->p;
	struct cond_av_list *other = data->other, *list, *cur;
	struct avtab_node *node_ptr;
	u8 found;


	/*
	 * For type rules we have to make certain there aren't any
	 * conflicting rules by searching the te_avtab and the
	 * cond_te_avtab.
	 */
	if (k->specified & AVTAB_TYPE) {
		if (avtab_search(&p->te_avtab, k)) {
			printk("security: type rule already exists outside of a conditional.");
			goto err;
		}
		/*
		 * If we are reading the false list other will be a pointer to
		 * the true list. We can have duplicate entries if there is only
		 * 1 other entry and it is in our true list.
		 *
		 * If we are reading the true list (other == NULL) there shouldn't
		 * be any other entries.
		 */
		if (other) {
			node_ptr = avtab_search_node(&p->te_cond_avtab, k);
			if (node_ptr) {
				if (avtab_search_node_next(node_ptr, k->specified)) {
					printk("security: too many conflicting type rules.");
					goto err;
				}
				found = 0;
				for (cur = other; cur != NULL; cur = cur->next) {
					if (cur->node == node_ptr) {
						found = 1;
						break;
					}
				}
				if (!found) {
					printk("security: conflicting type rules.\n");
					goto err;
				}
			}
		} else {
			if (avtab_search(&p->te_cond_avtab, k)) {
				printk("security: conflicting type rules when adding type rule for true.\n");
				goto err;
			}
		}
	}

	node_ptr = avtab_insert_nonunique(&p->te_cond_avtab, k, d);
	if (!node_ptr) {
		printk("security: could not insert rule.");
		goto err;
	}

	list = kmalloc(sizeof(struct cond_av_list), GFP_KERNEL);
	if (!list)
		goto err;
	memset(list, 0, sizeof(*list));

	list->node = node_ptr;
	if (!data->head)
		data->head = list;
	else
		data->tail->next = list;
	data->tail = list;
	return 0;

err:
	cond_av_list_destroy(data->head);
	data->head = NULL;
	return -1;
}

static int cond_read_av_list(struct policydb *p, void *fp, struct cond_av_list **ret_list, struct cond_av_list *other)
{
	int i, rc;
	__le32 buf[1];
	u32 len;
	struct cond_insertf_data data;

	*ret_list = NULL;

	len = 0;
	rc = next_entry(buf, fp, sizeof(u32));
	if (rc < 0)
		return -1;

	len = le32_to_cpu(buf[0]);
	if (len == 0) {
		return 0;
	}

	data.p = p;
	data.other = other;
	data.head = NULL;
	data.tail = NULL;
	for (i = 0; i < len; i++) {
		rc = avtab_read_item(fp, p->policyvers, &p->te_cond_avtab, cond_insertf, &data);
		if (rc)
			return rc;

	}

	*ret_list = data.head;
	return 0;
}

static int expr_isvalid(struct policydb *p, struct cond_expr *expr)
{
	if (expr->expr_type <= 0 || expr->expr_type > COND_LAST) {
		printk("security: conditional expressions uses unknown operator.\n");
		return 0;
	}

	if (expr->bool > p->p_bools.nprim) {
		printk("security: conditional expressions uses unknown bool.\n");
		return 0;
	}
	return 1;
}

static int cond_read_node(struct policydb *p, struct cond_node *node, void *fp)
{
	__le32 buf[2];
	u32 len, i;
	int rc;
	struct cond_expr *expr = NULL, *last = NULL;

	rc = next_entry(buf, fp, sizeof(u32));
	if (rc < 0)
		return -1;

	node->cur_state = le32_to_cpu(buf[0]);

	len = 0;
	rc = next_entry(buf, fp, sizeof(u32));
	if (rc < 0)
		return -1;

	/* expr */
	len = le32_to_cpu(buf[0]);

	for (i = 0; i < len; i++ ) {
		rc = next_entry(buf, fp, sizeof(u32) * 2);
		if (rc < 0)
			goto err;

		expr = kmalloc(sizeof(struct cond_expr), GFP_KERNEL);
		if (!expr) {
			goto err;
		}
		memset(expr, 0, sizeof(struct cond_expr));

		expr->expr_type = le32_to_cpu(buf[0]);
		expr->bool = le32_to_cpu(buf[1]);

		if (!expr_isvalid(p, expr)) {
			kfree(expr);
			goto err;
		}

		if (i == 0) {
			node->expr = expr;
		} else {
			last->next = expr;
		}
		last = expr;
	}

	if (cond_read_av_list(p, fp, &node->true_list, NULL) != 0)
		goto err;
	if (cond_read_av_list(p, fp, &node->false_list, node->true_list) != 0)
		goto err;
	return 0;
err:
	cond_node_destroy(node);
	return -1;
}

int cond_read_list(struct policydb *p, void *fp)
{
	struct cond_node *node, *last = NULL;
	__le32 buf[1];
	u32 i, len;
	int rc;

	rc = next_entry(buf, fp, sizeof buf);
	if (rc < 0)
		return -1;

	len = le32_to_cpu(buf[0]);

	for (i = 0; i < len; i++) {
		node = kmalloc(sizeof(struct cond_node), GFP_KERNEL);
		if (!node)
			goto err;
		memset(node, 0, sizeof(struct cond_node));

		if (cond_read_node(p, node, fp) != 0)
			goto err;

		if (i == 0) {
			p->cond_list = node;
		} else {
			last->next = node;
		}
		last = node;
	}
	return 0;
err:
	cond_list_destroy(p->cond_list);
	p->cond_list = NULL;
	return -1;
}

/* Determine whether additional permissions are granted by the conditional
 * av table, and if so, add them to the result
 */
void cond_compute_av(struct avtab *ctab, struct avtab_key *key, struct av_decision *avd)
{
	struct avtab_node *node;

	if(!ctab || !key || !avd)
		return;

	for(node = avtab_search_node(ctab, key); node != NULL;
				node = avtab_search_node_next(node, key->specified)) {
		if ( (u16) (AVTAB_ALLOWED|AVTAB_ENABLED) ==
		     (node->key.specified & (AVTAB_ALLOWED|AVTAB_ENABLED)))
			avd->allowed |= node->datum.data;
		if ( (u16) (AVTAB_AUDITDENY|AVTAB_ENABLED) ==
		     (node->key.specified & (AVTAB_AUDITDENY|AVTAB_ENABLED)))
			/* Since a '0' in an auditdeny mask represents a
			 * permission we do NOT want to audit (dontaudit), we use
			 * the '&' operand to ensure that all '0's in the mask
			 * are retained (much unlike the allow and auditallow cases).
			 */
			avd->auditdeny &= node->datum.data;
		if ( (u16) (AVTAB_AUDITALLOW|AVTAB_ENABLED) ==
		     (node->key.specified & (AVTAB_AUDITALLOW|AVTAB_ENABLED)))
			avd->auditallow |= node->datum.data;
	}
	return;
}

Privacy Policy