summaryrefslogtreecommitdiffstats
path: root/security/integrity/ima/ima_policy.c
blob: 93873a450ff720ff47bf5ec92b23b179bb0628dd (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
/*
 * Copyright (C) 2008 IBM Corporation
 * Author: Mimi Zohar <zohar@us.ibm.com>
 *
 * 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 of the License.
 *
 * ima_policy.c
 *	- initialize default measure policy rules
 *
 */
#include <linux/module.h>
#include <linux/list.h>
#include <linux/security.h>
#include <linux/magic.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/genhd.h>

#include "ima.h"

/* flags definitions */
#define IMA_FUNC	0x0001
#define IMA_MASK	0x0002
#define IMA_FSMAGIC	0x0004
#define IMA_UID		0x0008
#define IMA_FOWNER	0x0010
#define IMA_FSUUID	0x0020

#define UNKNOWN		0
#define MEASURE		0x0001	/* same as IMA_MEASURE */
#define DONT_MEASURE	0x0002
#define APPRAISE	0x0004	/* same as IMA_APPRAISE */
#define DONT_APPRAISE	0x0008
#define AUDIT		0x0040

#define MAX_LSM_RULES 6
enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
};

struct ima_rule_entry {
	struct list_head list;
	int action;
	unsigned int flags;
	enum ima_hooks func;
	int mask;
	unsigned long fsmagic;
	u8 fsuuid[16];
	kuid_t uid;
	kuid_t fowner;
	struct {
		void *rule;	/* LSM file metadata specific */
		void *args_p;	/* audit value */
		int type;	/* audit type */
	} lsm[MAX_LSM_RULES];
};

/*
 * Without LSM specific knowledge, the default policy can only be
 * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
 */

/*
 * The minimum rule set to allow for full TCB coverage.  Measures all files
 * opened or mmap for exec and everything read by root.  Dangerous because
 * normal users can easily run the machine out of memory simply building
 * and running executables.
 */
static struct ima_rule_entry default_rules[] = {
	{.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
	{.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
	 .flags = IMA_FUNC | IMA_MASK},
	{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
	 .flags = IMA_FUNC | IMA_MASK},
	{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
	 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
	{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
};

static struct ima_rule_entry default_appraise_rules[] = {
	{.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
	{.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
};

static LIST_HEAD(ima_default_rules);
static LIST_HEAD(ima_policy_rules);
static struct list_head *ima_rules;

static DEFINE_MUTEX(ima_rules_mutex);

static bool ima_use_tcb __initdata;
static int __init default_measure_policy_setup(char *str)
{
	ima_use_tcb = 1;
	return 1;
}
__setup("ima_tcb", default_measure_policy_setup);

static bool ima_use_appraise_tcb __initdata;
static int __init default_appraise_policy_setup(char *str)
{
	ima_use_appraise_tcb = 1;
	return 1;
}
__setup("ima_appraise_tcb", default_appraise_policy_setup);

/*
 * Although the IMA policy does not change, the LSM policy can be
 * reloaded, leaving the IMA LSM based rules referring to the old,
 * stale LSM policy.
 *
 * Update the IMA LSM based rules to reflect the reloaded LSM policy.
 * We assume the rules still exist; and BUG_ON() if they don't.
 */
static void ima_lsm_update_rules(void)
{
	struct ima_rule_entry *entry, *tmp;
	int result;
	int i;

	mutex_lock(&ima_rules_mutex);
	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
		for (i = 0; i < MAX_LSM_RULES; i++) {
			if (!entry->lsm[i].rule)
				continue;
			result = security_filter_rule_init(entry->lsm[i].type,
							   Audit_equal,
							   entry->lsm[i].args_p,
							   &entry->lsm[i].rule);
			BUG_ON(!entry->lsm[i].rule);
		}
	}
	mutex_unlock(&ima_rules_mutex);
}

/**
 * ima_match_rules - determine whether an inode matches the measure rule.
 * @rule: a pointer to a rule
 * @inode: a pointer to an inode
 * @func: LIM hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 *
 * Returns true on rule match, false on failure.
 */
static bool ima_match_rules(struct ima_rule_entry *rule,
			    struct inode *inode, enum ima_hooks func, int mask)
{
	struct task_struct *tsk = current;
	const struct cred *cred = current_cred();
	int i;

	if ((rule->flags & IMA_FUNC) &&
	    (rule->func != func && func != POST_SETATTR))
		return false;
	if ((rule->flags & IMA_MASK) &&
	    (rule->mask != mask && func != POST_SETATTR))
		return false;
	if ((rule->flags & IMA_FSMAGIC)
	    && rule->fsmagic != inode->i_sb->s_magic)
		return false;
	if ((rule->flags & IMA_FSUUID) &&
	    memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
		return false;
	if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
		return false;
	if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
		return false;
	for (i = 0; i < MAX_LSM_RULES; i++) {
		int rc = 0;
		u32 osid, sid;
		int retried = 0;

		if (!rule->lsm[i].rule)
			continue;
retry:
		switch (i) {
		case LSM_OBJ_USER:
		case LSM_OBJ_ROLE:
		case LSM_OBJ_TYPE:
			security_inode_getsecid(inode, &osid);
			rc = security_filter_rule_match(osid,
							rule->lsm[i].type,
							Audit_equal,
							rule->lsm[i].rule,
							NULL);
			break;
		case LSM_SUBJ_USER:
		case LSM_SUBJ_ROLE:
		case LSM_SUBJ_TYPE:
			security_task_getsecid(tsk, &sid);
			rc = security_filter_rule_match(sid,
							rule->lsm[i].type,
							Audit_equal,
							rule->lsm[i].rule,
							NULL);
		default:
			break;
		}
		if ((rc < 0) && (!retried)) {
			retried = 1;
			ima_lsm_update_rules();
			goto retry;
		}
		if (!rc)
			return false;
	}
	return true;
}

/*
 * In addition to knowing that we need to appraise the file in general,
 * we need to differentiate between calling hooks, for hook specific rules.
 */
static int get_subaction(struct ima_rule_entry *rule, int func)
{
	if (!(rule->flags & IMA_FUNC))
		return IMA_FILE_APPRAISE;

	switch (func) {
	case MMAP_CHECK:
		return IMA_MMAP_APPRAISE;
	case BPRM_CHECK:
		return IMA_BPRM_APPRAISE;
	case MODULE_CHECK:
		return IMA_MODULE_APPRAISE;
	case FILE_CHECK:
	default:
		return IMA_FILE_APPRAISE;
	}
}

/**
 * ima_match_policy - decision based on LSM and other conditions
 * @inode: pointer to an inode for which the policy decision is being made
 * @func: IMA hook identifier
 * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
 *
 * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
 * conditions.
 *
 * (There is no need for locking when walking the policy list,
 * as elements in the list are never deleted, nor does the list
 * change.)
 */
int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
		     int flags)
{
	struct ima_rule_entry *entry;
	int action = 0, actmask = flags | (flags << 1);

	list_for_each_entry(entry, ima_rules, list) {

		if (!(entry->action & actmask))
			continue;

		if (!ima_match_rules(entry, inode, func, mask))
			continue;

		action |= entry->flags & IMA_ACTION_FLAGS;

		action |= entry->action & IMA_DO_MASK;
		if (entry->action & IMA_APPRAISE)
			action |= get_subaction(entry, func);

		if (entry->action & IMA_DO_MASK)
			actmask &= ~(entry->action | entry->action << 1);
		else
			actmask &= ~(entry->action | entry->action >> 1);

		if (!actmask)
			break;
	}

	return action;
}

/**
 * ima_init_policy - initialize the default measure rules.
 *
 * ima_rules points to either the ima_default_rules or the
 * the new ima_policy_rules.
 */
void __init ima_init_policy(void)
{
	int i, measure_entries, appraise_entries;

	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
	measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
	appraise_entries = ima_use_appraise_tcb ?
			 ARRAY_SIZE(default_appraise_rules) : 0;

	for (i = 0; i < measure_entries + appraise_entries; i++) {
		if (i < measure_entries)
			list_add_tail(&default_rules[i].list,
				      &ima_default_rules);
		else {
			int j = i - measure_entries;

			list_add_tail(&default_appraise_rules[j].list,
				      &ima_default_rules);
		}
	}

	ima_rules = &ima_default_rules;
}

/**
 * ima_update_policy - update default_rules with new measure rules
 *
 * Called on file .release to update the default rules with a complete new
 * policy.  Once updated, the policy is locked, no additional rules can be
 * added to the policy.
 */
void ima_update_policy(void)
{
	static const char op[] = "policy_update";
	const char *cause = "already exists";
	int result = 1;
	int audit_info = 0;

	if (ima_rules == &ima_default_rules) {
		ima_rules = &ima_policy_rules;
		cause = "complete";
		result = 0;
	}
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
			    NULL, op, cause, result, audit_info);
}

enum {
	Opt_err = -1,
	Opt_measure = 1, Opt_dont_measure,
	Opt_appraise, Opt_dont_appraise,
	Opt_audit,
	Opt_obj_user, Opt_obj_role, Opt_obj_type,
	Opt_subj_user, Opt_subj_role, Opt_subj_type,
	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner,
	Opt_appraise_type, Opt_fsuuid
};

static match_table_t policy_tokens = {
	{Opt_measure, "measure"},
	{Opt_dont_measure, "dont_measure"},
	{Opt_appraise, "appraise"},
	{Opt_dont_appraise, "dont_appraise"},
	{Opt_audit, "audit"},
	{Opt_obj_user, "obj_user=%s"},
	{Opt_obj_role, "obj_role=%s"},
	{Opt_obj_type, "obj_type=%s"},
	{Opt_subj_user, "subj_user=%s"},
	{Opt_subj_role, "subj_role=%s"},
	{Opt_subj_type, "subj_type=%s"},
	{Opt_func, "func=%s"},
	{Opt_mask, "mask=%s"},
	{Opt_fsmagic, "fsmagic=%s"},
	{Opt_fsuuid, "fsuuid=%s"},
	{Opt_uid, "uid=%s"},
	{Opt_fowner, "fowner=%s"},
	{Opt_appraise_type, "appraise_type=%s"},
	{Opt_err, NULL}
};

static int ima_lsm_rule_init(struct ima_rule_entry *entry,
			     substring_t *args, int lsm_rule, int audit_type)
{
	int result;

	if (entry->lsm[lsm_rule].rule)
		return -EINVAL;

	entry->lsm[lsm_rule].args_p = match_strdup(args);
	if (!entry->lsm[lsm_rule].args_p)
		return -ENOMEM;

	entry->lsm[lsm_rule].type = audit_type;
	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
					   Audit_equal,
					   entry->lsm[lsm_rule].args_p,
					   &entry->lsm[lsm_rule].rule);
	if (!entry->lsm[lsm_rule].rule) {
		kfree(entry->lsm[lsm_rule].args_p);
		return -EINVAL;
	}

	return result;
}

static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
{
	audit_log_format(ab, "%s=", key);
	audit_log_untrustedstring(ab, value);
	audit_log_format(ab, " ");
}

static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
{
	struct audit_buffer *ab;
	char *p;
	int result = 0;

	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);

	entry->uid = INVALID_UID;
	entry->fowner = INVALID_UID;
	entry->action = UNKNOWN;
	while ((p = strsep(&rule, " \t")) != NULL) {
		substring_t args[MAX_OPT_ARGS];
		int token;
		unsigned long lnum;

		if (result < 0)
			break;
		if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
			continue;
		token = match_token(p, policy_tokens, args);
		switch (token) {
		case Opt_measure:
			ima_log_string(ab, "action", "measure");

			if (entry->action != UNKNOWN)
				result = -EINVAL;

			entry->action = MEASURE;
			break;
		case Opt_dont_measure:
			ima_log_string(ab, "action", "dont_measure");

			if (entry->action != UNKNOWN)
				result = -EINVAL;

			entry->action = DONT_MEASURE;
			break;
		case Opt_appraise:
			ima_log_string(ab, "action", "appraise");

			if (entry->action != UNKNOWN)
				result = -EINVAL;

			entry->action = APPRAISE;
			break;
		case Opt_dont_appraise:
			ima_log_string(ab, "action", "dont_appraise");

			if (entry->action != UNKNOWN)
				result = -EINVAL;

			entry->action = DONT_APPRAISE;
			break;
		case Opt_audit:
			ima_log_string(ab, "action", "audit");

			if (entry->action != UNKNOWN)
				result = -EINVAL;

			entry->action = AUDIT;
			break;
		case Opt_func:
			ima_log_string(ab, "func", args[0].from);

			if (entry->func)
				result = -EINVAL;

			if (strcmp(args[0].from, "FILE_CHECK") == 0)
				entry->func = FILE_CHECK;
			/* PATH_CHECK is for backwards compat */
			else if (strcmp(args[0].from, "PATH_CHECK") == 0)
				entry->func = FILE_CHECK;
			else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
				entry->func = MODULE_CHECK;
			else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
				|| (strcmp(args[0].from, "MMAP_CHECK") == 0))
				entry->func = MMAP_CHECK;
			else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
				entry->func = BPRM_CHECK;
			else
				result = -EINVAL;
			if (!result)
				entry->flags |= IMA_FUNC;
			break;
		case Opt_mask:
			ima_log_string(ab, "mask", args[0].from);

			if (entry->mask)
				result = -EINVAL;

			if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
				entry->mask = MAY_EXEC;
			else if (strcmp(args[0].from, "MAY_WRITE") == 0)
				entry->mask = MAY_WRITE;
			else if (strcmp(args[0].from, "MAY_READ") == 0)
				entry->mask = MAY_READ;
			else if (strcmp(args[0].from, "MAY_APPEND") == 0)
				entry->mask = MAY_APPEND;
			else
				result = -EINVAL;
			if (!result)
				entry->flags |= IMA_MASK;
			break;
		case Opt_fsmagic:
			ima_log_string(ab, "fsmagic", args[0].from);

			if (entry->fsmagic) {
				result = -EINVAL;
				break;
			}

			result = kstrtoul(args[0].from, 16, &entry->fsmagic);
			if (!result)
				entry->flags |= IMA_FSMAGIC;
			break;
		case Opt_fsuuid:
			ima_log_string(ab, "fsuuid", args[0].from);

			if (memchr_inv(entry->fsuuid, 0x00,
				       sizeof(entry->fsuuid))) {
				result = -EINVAL;
				break;
			}

			result = blk_part_pack_uuid(args[0].from,
						    entry->fsuuid);
			if (!result)
				entry->flags |= IMA_FSUUID;
			break;
		case Opt_uid:
			ima_log_string(ab, "uid", args[0].from);

			if (uid_valid(entry->uid)) {
				result = -EINVAL;
				break;
			}

			result = kstrtoul(args[0].from, 10, &lnum);
			if (!result) {
				entry->uid = make_kuid(current_user_ns(), (uid_t)lnum);
				if (!uid_valid(entry->uid) || (((uid_t)lnum) != lnum))
					result = -EINVAL;
				else
					entry->flags |= IMA_UID;
			}
			break;
		case Opt_fowner:
			ima_log_string(ab, "fowner", args[0].from);

			if (uid_valid(entry->fowner)) {
				result = -EINVAL;
				break;
			}

			result = kstrtoul(args[0].from, 10, &lnum);
			if (!result) {
				entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
				if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
					result = -EINVAL;
				else
					entry->flags |= IMA_FOWNER;
			}
			break;
		case Opt_obj_user:
			ima_log_string(ab, "obj_user", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_OBJ_USER,
						   AUDIT_OBJ_USER);
			break;
		case Opt_obj_role:
			ima_log_string(ab, "obj_role", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_OBJ_ROLE,
						   AUDIT_OBJ_ROLE);
			break;
		case Opt_obj_type:
			ima_log_string(ab, "obj_type", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_OBJ_TYPE,
						   AUDIT_OBJ_TYPE);
			break;
		case Opt_subj_user:
			ima_log_string(ab, "subj_user", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_SUBJ_USER,
						   AUDIT_SUBJ_USER);
			break;
		case Opt_subj_role:
			ima_log_string(ab, "subj_role", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_SUBJ_ROLE,
						   AUDIT_SUBJ_ROLE);
			break;
		case Opt_subj_type:
			ima_log_string(ab, "subj_type", args[0].from);
			result = ima_lsm_rule_init(entry, args,
						   LSM_SUBJ_TYPE,
						   AUDIT_SUBJ_TYPE);
			break;
		case Opt_appraise_type:
			if (entry->action != APPRAISE) {
				result = -EINVAL;
				break;
			}

			ima_log_string(ab, "appraise_type", args[0].from);
			if ((strcmp(args[0].from, "imasig")) == 0)
				entry->flags |= IMA_DIGSIG_REQUIRED;
			else
				result = -EINVAL;
			break;
		case Opt_err:
			ima_log_string(ab, "UNKNOWN", p);
			result = -EINVAL;
			break;
		}
	}
	if (!result && (entry->action == UNKNOWN))
		result = -EINVAL;
	else if (entry->func == MODULE_CHECK)
		ima_appraise |= IMA_APPRAISE_MODULES;
	audit_log_format(ab, "res=%d", !result);
	audit_log_end(ab);
	return result;
}

/**
 * ima_parse_add_rule - add a rule to ima_policy_rules
 * @rule - ima measurement policy rule
 *
 * Uses a mutex to protect the policy list from multiple concurrent writers.
 * Returns the length of the rule parsed, an error code on failure
 */
ssize_t ima_parse_add_rule(char *rule)
{
	static const char op[] = "update_policy";
	char *p;
	struct ima_rule_entry *entry;
	ssize_t result, len;
	int audit_info = 0;

	/* Prevent installed policy from changing */
	if (ima_rules != &ima_default_rules) {
		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
				    NULL, op, "already exists",
				    -EACCES, audit_info);
		return -EACCES;
	}

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
				    NULL, op, "-ENOMEM", -ENOMEM, audit_info);
		return -ENOMEM;
	}

	INIT_LIST_HEAD(&entry->list);

	p = strsep(&rule, "\n");
	len = strlen(p) + 1;

	if (*p == '#') {
		kfree(entry);
		return len;
	}

	result = ima_parse_rule(p, entry);
	if (result) {
		kfree(entry);
		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
				    NULL, op, "invalid policy", result,
				    audit_info);
		return result;
	}

	mutex_lock(&ima_rules_mutex);
	list_add_tail(&entry->list, &ima_policy_rules);
	mutex_unlock(&ima_rules_mutex);

	return len;
}

/* ima_delete_rules called to cleanup invalid policy */
void ima_delete_rules(void)
{
	struct ima_rule_entry *entry, *tmp;
	int i;

	mutex_lock(&ima_rules_mutex);
	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
		for (i = 0; i < MAX_LSM_RULES; i++)
			kfree(entry->lsm[i].args_p);

		list_del(&entry->list);
		kfree(entry);
	}
	mutex_unlock(&ima_rules_mutex);
}