1 /*
2  * Copyright (C) 2008 IBM Corporation
3  * Author: Mimi Zohar <zohar@us.ibm.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License as published by
7  * the Free Software Foundation, version 2 of the License.
8  *
9  * ima_policy.c
10  *	- initialize default measure policy rules
11  *
12  */
13 #include <linux/module.h>
14 #include <linux/list.h>
15 #include <linux/security.h>
16 #include <linux/magic.h>
17 #include <linux/parser.h>
18 #include <linux/slab.h>
19 #include <linux/genhd.h>
20 
21 #include "ima.h"
22 
23 /* flags definitions */
24 #define IMA_FUNC	0x0001
25 #define IMA_MASK	0x0002
26 #define IMA_FSMAGIC	0x0004
27 #define IMA_UID		0x0008
28 #define IMA_FOWNER	0x0010
29 #define IMA_FSUUID	0x0020
30 
31 #define UNKNOWN		0
32 #define MEASURE		0x0001	/* same as IMA_MEASURE */
33 #define DONT_MEASURE	0x0002
34 #define APPRAISE	0x0004	/* same as IMA_APPRAISE */
35 #define DONT_APPRAISE	0x0008
36 #define AUDIT		0x0040
37 
38 #define MAX_LSM_RULES 6
39 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
40 	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
41 };
42 
43 struct ima_rule_entry {
44 	struct list_head list;
45 	int action;
46 	unsigned int flags;
47 	enum ima_hooks func;
48 	int mask;
49 	unsigned long fsmagic;
50 	u8 fsuuid[16];
51 	kuid_t uid;
52 	kuid_t fowner;
53 	struct {
54 		void *rule;	/* LSM file metadata specific */
55 		void *args_p;	/* audit value */
56 		int type;	/* audit type */
57 	} lsm[MAX_LSM_RULES];
58 };
59 
60 /*
61  * Without LSM specific knowledge, the default policy can only be
62  * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
63  */
64 
65 /*
66  * The minimum rule set to allow for full TCB coverage.  Measures all files
67  * opened or mmap for exec and everything read by root.  Dangerous because
68  * normal users can easily run the machine out of memory simply building
69  * and running executables.
70  */
71 static struct ima_rule_entry default_rules[] = {
72 	{.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
73 	{.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
74 	{.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
75 	{.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
76 	{.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
77 	{.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
78 	{.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
79 	{.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
80 	{.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
81 	 .flags = IMA_FUNC | IMA_MASK},
82 	{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
83 	 .flags = IMA_FUNC | IMA_MASK},
84 	{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
85 	 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
86 	{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
87 };
88 
89 static struct ima_rule_entry default_appraise_rules[] = {
90 	{.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
91 	{.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
92 	{.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
93 	{.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC},
94 	{.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC},
95 	{.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC},
96 	{.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC},
97 	{.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC},
98 	{.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
99 	{.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
100 	{.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
101 };
102 
103 static LIST_HEAD(ima_default_rules);
104 static LIST_HEAD(ima_policy_rules);
105 static struct list_head *ima_rules;
106 
107 static DEFINE_MUTEX(ima_rules_mutex);
108 
109 static bool ima_use_tcb __initdata;
110 static int __init default_measure_policy_setup(char *str)
111 {
112 	ima_use_tcb = 1;
113 	return 1;
114 }
115 __setup("ima_tcb", default_measure_policy_setup);
116 
117 static bool ima_use_appraise_tcb __initdata;
118 static int __init default_appraise_policy_setup(char *str)
119 {
120 	ima_use_appraise_tcb = 1;
121 	return 1;
122 }
123 __setup("ima_appraise_tcb", default_appraise_policy_setup);
124 
125 /*
126  * Although the IMA policy does not change, the LSM policy can be
127  * reloaded, leaving the IMA LSM based rules referring to the old,
128  * stale LSM policy.
129  *
130  * Update the IMA LSM based rules to reflect the reloaded LSM policy.
131  * We assume the rules still exist; and BUG_ON() if they don't.
132  */
133 static void ima_lsm_update_rules(void)
134 {
135 	struct ima_rule_entry *entry, *tmp;
136 	int result;
137 	int i;
138 
139 	mutex_lock(&ima_rules_mutex);
140 	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
141 		for (i = 0; i < MAX_LSM_RULES; i++) {
142 			if (!entry->lsm[i].rule)
143 				continue;
144 			result = security_filter_rule_init(entry->lsm[i].type,
145 							   Audit_equal,
146 							   entry->lsm[i].args_p,
147 							   &entry->lsm[i].rule);
148 			BUG_ON(!entry->lsm[i].rule);
149 		}
150 	}
151 	mutex_unlock(&ima_rules_mutex);
152 }
153 
154 /**
155  * ima_match_rules - determine whether an inode matches the measure rule.
156  * @rule: a pointer to a rule
157  * @inode: a pointer to an inode
158  * @func: LIM hook identifier
159  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
160  *
161  * Returns true on rule match, false on failure.
162  */
163 static bool ima_match_rules(struct ima_rule_entry *rule,
164 			    struct inode *inode, enum ima_hooks func, int mask)
165 {
166 	struct task_struct *tsk = current;
167 	const struct cred *cred = current_cred();
168 	int i;
169 
170 	if ((rule->flags & IMA_FUNC) &&
171 	    (rule->func != func && func != POST_SETATTR))
172 		return false;
173 	if ((rule->flags & IMA_MASK) &&
174 	    (rule->mask != mask && func != POST_SETATTR))
175 		return false;
176 	if ((rule->flags & IMA_FSMAGIC)
177 	    && rule->fsmagic != inode->i_sb->s_magic)
178 		return false;
179 	if ((rule->flags & IMA_FSUUID) &&
180 	    memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
181 		return false;
182 	if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
183 		return false;
184 	if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
185 		return false;
186 	for (i = 0; i < MAX_LSM_RULES; i++) {
187 		int rc = 0;
188 		u32 osid, sid;
189 		int retried = 0;
190 
191 		if (!rule->lsm[i].rule)
192 			continue;
193 retry:
194 		switch (i) {
195 		case LSM_OBJ_USER:
196 		case LSM_OBJ_ROLE:
197 		case LSM_OBJ_TYPE:
198 			security_inode_getsecid(inode, &osid);
199 			rc = security_filter_rule_match(osid,
200 							rule->lsm[i].type,
201 							Audit_equal,
202 							rule->lsm[i].rule,
203 							NULL);
204 			break;
205 		case LSM_SUBJ_USER:
206 		case LSM_SUBJ_ROLE:
207 		case LSM_SUBJ_TYPE:
208 			security_task_getsecid(tsk, &sid);
209 			rc = security_filter_rule_match(sid,
210 							rule->lsm[i].type,
211 							Audit_equal,
212 							rule->lsm[i].rule,
213 							NULL);
214 		default:
215 			break;
216 		}
217 		if ((rc < 0) && (!retried)) {
218 			retried = 1;
219 			ima_lsm_update_rules();
220 			goto retry;
221 		}
222 		if (!rc)
223 			return false;
224 	}
225 	return true;
226 }
227 
228 /*
229  * In addition to knowing that we need to appraise the file in general,
230  * we need to differentiate between calling hooks, for hook specific rules.
231  */
232 static int get_subaction(struct ima_rule_entry *rule, int func)
233 {
234 	if (!(rule->flags & IMA_FUNC))
235 		return IMA_FILE_APPRAISE;
236 
237 	switch (func) {
238 	case MMAP_CHECK:
239 		return IMA_MMAP_APPRAISE;
240 	case BPRM_CHECK:
241 		return IMA_BPRM_APPRAISE;
242 	case MODULE_CHECK:
243 		return IMA_MODULE_APPRAISE;
244 	case FILE_CHECK:
245 	default:
246 		return IMA_FILE_APPRAISE;
247 	}
248 }
249 
250 /**
251  * ima_match_policy - decision based on LSM and other conditions
252  * @inode: pointer to an inode for which the policy decision is being made
253  * @func: IMA hook identifier
254  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
255  *
256  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
257  * conditions.
258  *
259  * (There is no need for locking when walking the policy list,
260  * as elements in the list are never deleted, nor does the list
261  * change.)
262  */
263 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
264 		     int flags)
265 {
266 	struct ima_rule_entry *entry;
267 	int action = 0, actmask = flags | (flags << 1);
268 
269 	list_for_each_entry(entry, ima_rules, list) {
270 
271 		if (!(entry->action & actmask))
272 			continue;
273 
274 		if (!ima_match_rules(entry, inode, func, mask))
275 			continue;
276 
277 		action |= entry->flags & IMA_ACTION_FLAGS;
278 
279 		action |= entry->action & IMA_DO_MASK;
280 		if (entry->action & IMA_APPRAISE)
281 			action |= get_subaction(entry, func);
282 
283 		if (entry->action & IMA_DO_MASK)
284 			actmask &= ~(entry->action | entry->action << 1);
285 		else
286 			actmask &= ~(entry->action | entry->action >> 1);
287 
288 		if (!actmask)
289 			break;
290 	}
291 
292 	return action;
293 }
294 
295 /**
296  * ima_init_policy - initialize the default measure rules.
297  *
298  * ima_rules points to either the ima_default_rules or the
299  * the new ima_policy_rules.
300  */
301 void __init ima_init_policy(void)
302 {
303 	int i, measure_entries, appraise_entries;
304 
305 	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
306 	measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
307 	appraise_entries = ima_use_appraise_tcb ?
308 			 ARRAY_SIZE(default_appraise_rules) : 0;
309 
310 	for (i = 0; i < measure_entries + appraise_entries; i++) {
311 		if (i < measure_entries)
312 			list_add_tail(&default_rules[i].list,
313 				      &ima_default_rules);
314 		else {
315 			int j = i - measure_entries;
316 
317 			list_add_tail(&default_appraise_rules[j].list,
318 				      &ima_default_rules);
319 		}
320 	}
321 
322 	ima_rules = &ima_default_rules;
323 }
324 
325 /**
326  * ima_update_policy - update default_rules with new measure rules
327  *
328  * Called on file .release to update the default rules with a complete new
329  * policy.  Once updated, the policy is locked, no additional rules can be
330  * added to the policy.
331  */
332 void ima_update_policy(void)
333 {
334 	static const char op[] = "policy_update";
335 	const char *cause = "already exists";
336 	int result = 1;
337 	int audit_info = 0;
338 
339 	if (ima_rules == &ima_default_rules) {
340 		ima_rules = &ima_policy_rules;
341 		cause = "complete";
342 		result = 0;
343 	}
344 	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
345 			    NULL, op, cause, result, audit_info);
346 }
347 
348 enum {
349 	Opt_err = -1,
350 	Opt_measure = 1, Opt_dont_measure,
351 	Opt_appraise, Opt_dont_appraise,
352 	Opt_audit,
353 	Opt_obj_user, Opt_obj_role, Opt_obj_type,
354 	Opt_subj_user, Opt_subj_role, Opt_subj_type,
355 	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner,
356 	Opt_appraise_type, Opt_fsuuid, Opt_permit_directio
357 };
358 
359 static match_table_t policy_tokens = {
360 	{Opt_measure, "measure"},
361 	{Opt_dont_measure, "dont_measure"},
362 	{Opt_appraise, "appraise"},
363 	{Opt_dont_appraise, "dont_appraise"},
364 	{Opt_audit, "audit"},
365 	{Opt_obj_user, "obj_user=%s"},
366 	{Opt_obj_role, "obj_role=%s"},
367 	{Opt_obj_type, "obj_type=%s"},
368 	{Opt_subj_user, "subj_user=%s"},
369 	{Opt_subj_role, "subj_role=%s"},
370 	{Opt_subj_type, "subj_type=%s"},
371 	{Opt_func, "func=%s"},
372 	{Opt_mask, "mask=%s"},
373 	{Opt_fsmagic, "fsmagic=%s"},
374 	{Opt_fsuuid, "fsuuid=%s"},
375 	{Opt_uid, "uid=%s"},
376 	{Opt_fowner, "fowner=%s"},
377 	{Opt_appraise_type, "appraise_type=%s"},
378 	{Opt_permit_directio, "permit_directio"},
379 	{Opt_err, NULL}
380 };
381 
382 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
383 			     substring_t *args, int lsm_rule, int audit_type)
384 {
385 	int result;
386 
387 	if (entry->lsm[lsm_rule].rule)
388 		return -EINVAL;
389 
390 	entry->lsm[lsm_rule].args_p = match_strdup(args);
391 	if (!entry->lsm[lsm_rule].args_p)
392 		return -ENOMEM;
393 
394 	entry->lsm[lsm_rule].type = audit_type;
395 	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
396 					   Audit_equal,
397 					   entry->lsm[lsm_rule].args_p,
398 					   &entry->lsm[lsm_rule].rule);
399 	if (!entry->lsm[lsm_rule].rule) {
400 		kfree(entry->lsm[lsm_rule].args_p);
401 		return -EINVAL;
402 	}
403 
404 	return result;
405 }
406 
407 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
408 {
409 	audit_log_format(ab, "%s=", key);
410 	audit_log_untrustedstring(ab, value);
411 	audit_log_format(ab, " ");
412 }
413 
414 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
415 {
416 	struct audit_buffer *ab;
417 	char *p;
418 	int result = 0;
419 
420 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
421 
422 	entry->uid = INVALID_UID;
423 	entry->fowner = INVALID_UID;
424 	entry->action = UNKNOWN;
425 	while ((p = strsep(&rule, " \t")) != NULL) {
426 		substring_t args[MAX_OPT_ARGS];
427 		int token;
428 		unsigned long lnum;
429 
430 		if (result < 0)
431 			break;
432 		if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
433 			continue;
434 		token = match_token(p, policy_tokens, args);
435 		switch (token) {
436 		case Opt_measure:
437 			ima_log_string(ab, "action", "measure");
438 
439 			if (entry->action != UNKNOWN)
440 				result = -EINVAL;
441 
442 			entry->action = MEASURE;
443 			break;
444 		case Opt_dont_measure:
445 			ima_log_string(ab, "action", "dont_measure");
446 
447 			if (entry->action != UNKNOWN)
448 				result = -EINVAL;
449 
450 			entry->action = DONT_MEASURE;
451 			break;
452 		case Opt_appraise:
453 			ima_log_string(ab, "action", "appraise");
454 
455 			if (entry->action != UNKNOWN)
456 				result = -EINVAL;
457 
458 			entry->action = APPRAISE;
459 			break;
460 		case Opt_dont_appraise:
461 			ima_log_string(ab, "action", "dont_appraise");
462 
463 			if (entry->action != UNKNOWN)
464 				result = -EINVAL;
465 
466 			entry->action = DONT_APPRAISE;
467 			break;
468 		case Opt_audit:
469 			ima_log_string(ab, "action", "audit");
470 
471 			if (entry->action != UNKNOWN)
472 				result = -EINVAL;
473 
474 			entry->action = AUDIT;
475 			break;
476 		case Opt_func:
477 			ima_log_string(ab, "func", args[0].from);
478 
479 			if (entry->func)
480 				result = -EINVAL;
481 
482 			if (strcmp(args[0].from, "FILE_CHECK") == 0)
483 				entry->func = FILE_CHECK;
484 			/* PATH_CHECK is for backwards compat */
485 			else if (strcmp(args[0].from, "PATH_CHECK") == 0)
486 				entry->func = FILE_CHECK;
487 			else if (strcmp(args[0].from, "MODULE_CHECK") == 0)
488 				entry->func = MODULE_CHECK;
489 			else if ((strcmp(args[0].from, "FILE_MMAP") == 0)
490 				|| (strcmp(args[0].from, "MMAP_CHECK") == 0))
491 				entry->func = MMAP_CHECK;
492 			else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
493 				entry->func = BPRM_CHECK;
494 			else
495 				result = -EINVAL;
496 			if (!result)
497 				entry->flags |= IMA_FUNC;
498 			break;
499 		case Opt_mask:
500 			ima_log_string(ab, "mask", args[0].from);
501 
502 			if (entry->mask)
503 				result = -EINVAL;
504 
505 			if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
506 				entry->mask = MAY_EXEC;
507 			else if (strcmp(args[0].from, "MAY_WRITE") == 0)
508 				entry->mask = MAY_WRITE;
509 			else if (strcmp(args[0].from, "MAY_READ") == 0)
510 				entry->mask = MAY_READ;
511 			else if (strcmp(args[0].from, "MAY_APPEND") == 0)
512 				entry->mask = MAY_APPEND;
513 			else
514 				result = -EINVAL;
515 			if (!result)
516 				entry->flags |= IMA_MASK;
517 			break;
518 		case Opt_fsmagic:
519 			ima_log_string(ab, "fsmagic", args[0].from);
520 
521 			if (entry->fsmagic) {
522 				result = -EINVAL;
523 				break;
524 			}
525 
526 			result = kstrtoul(args[0].from, 16, &entry->fsmagic);
527 			if (!result)
528 				entry->flags |= IMA_FSMAGIC;
529 			break;
530 		case Opt_fsuuid:
531 			ima_log_string(ab, "fsuuid", args[0].from);
532 
533 			if (memchr_inv(entry->fsuuid, 0x00,
534 				       sizeof(entry->fsuuid))) {
535 				result = -EINVAL;
536 				break;
537 			}
538 
539 			result = blk_part_pack_uuid(args[0].from,
540 						    entry->fsuuid);
541 			if (!result)
542 				entry->flags |= IMA_FSUUID;
543 			break;
544 		case Opt_uid:
545 			ima_log_string(ab, "uid", args[0].from);
546 
547 			if (uid_valid(entry->uid)) {
548 				result = -EINVAL;
549 				break;
550 			}
551 
552 			result = kstrtoul(args[0].from, 10, &lnum);
553 			if (!result) {
554 				entry->uid = make_kuid(current_user_ns(), (uid_t)lnum);
555 				if (!uid_valid(entry->uid) || (((uid_t)lnum) != lnum))
556 					result = -EINVAL;
557 				else
558 					entry->flags |= IMA_UID;
559 			}
560 			break;
561 		case Opt_fowner:
562 			ima_log_string(ab, "fowner", args[0].from);
563 
564 			if (uid_valid(entry->fowner)) {
565 				result = -EINVAL;
566 				break;
567 			}
568 
569 			result = kstrtoul(args[0].from, 10, &lnum);
570 			if (!result) {
571 				entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum);
572 				if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum))
573 					result = -EINVAL;
574 				else
575 					entry->flags |= IMA_FOWNER;
576 			}
577 			break;
578 		case Opt_obj_user:
579 			ima_log_string(ab, "obj_user", args[0].from);
580 			result = ima_lsm_rule_init(entry, args,
581 						   LSM_OBJ_USER,
582 						   AUDIT_OBJ_USER);
583 			break;
584 		case Opt_obj_role:
585 			ima_log_string(ab, "obj_role", args[0].from);
586 			result = ima_lsm_rule_init(entry, args,
587 						   LSM_OBJ_ROLE,
588 						   AUDIT_OBJ_ROLE);
589 			break;
590 		case Opt_obj_type:
591 			ima_log_string(ab, "obj_type", args[0].from);
592 			result = ima_lsm_rule_init(entry, args,
593 						   LSM_OBJ_TYPE,
594 						   AUDIT_OBJ_TYPE);
595 			break;
596 		case Opt_subj_user:
597 			ima_log_string(ab, "subj_user", args[0].from);
598 			result = ima_lsm_rule_init(entry, args,
599 						   LSM_SUBJ_USER,
600 						   AUDIT_SUBJ_USER);
601 			break;
602 		case Opt_subj_role:
603 			ima_log_string(ab, "subj_role", args[0].from);
604 			result = ima_lsm_rule_init(entry, args,
605 						   LSM_SUBJ_ROLE,
606 						   AUDIT_SUBJ_ROLE);
607 			break;
608 		case Opt_subj_type:
609 			ima_log_string(ab, "subj_type", args[0].from);
610 			result = ima_lsm_rule_init(entry, args,
611 						   LSM_SUBJ_TYPE,
612 						   AUDIT_SUBJ_TYPE);
613 			break;
614 		case Opt_appraise_type:
615 			if (entry->action != APPRAISE) {
616 				result = -EINVAL;
617 				break;
618 			}
619 
620 			ima_log_string(ab, "appraise_type", args[0].from);
621 			if ((strcmp(args[0].from, "imasig")) == 0)
622 				entry->flags |= IMA_DIGSIG_REQUIRED;
623 			else
624 				result = -EINVAL;
625 			break;
626 		case Opt_permit_directio:
627 			entry->flags |= IMA_PERMIT_DIRECTIO;
628 			break;
629 		case Opt_err:
630 			ima_log_string(ab, "UNKNOWN", p);
631 			result = -EINVAL;
632 			break;
633 		}
634 	}
635 	if (!result && (entry->action == UNKNOWN))
636 		result = -EINVAL;
637 	else if (entry->func == MODULE_CHECK)
638 		ima_appraise |= IMA_APPRAISE_MODULES;
639 	audit_log_format(ab, "res=%d", !result);
640 	audit_log_end(ab);
641 	return result;
642 }
643 
644 /**
645  * ima_parse_add_rule - add a rule to ima_policy_rules
646  * @rule - ima measurement policy rule
647  *
648  * Uses a mutex to protect the policy list from multiple concurrent writers.
649  * Returns the length of the rule parsed, an error code on failure
650  */
651 ssize_t ima_parse_add_rule(char *rule)
652 {
653 	static const char op[] = "update_policy";
654 	char *p;
655 	struct ima_rule_entry *entry;
656 	ssize_t result, len;
657 	int audit_info = 0;
658 
659 	/* Prevent installed policy from changing */
660 	if (ima_rules != &ima_default_rules) {
661 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
662 				    NULL, op, "already exists",
663 				    -EACCES, audit_info);
664 		return -EACCES;
665 	}
666 
667 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
668 	if (!entry) {
669 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
670 				    NULL, op, "-ENOMEM", -ENOMEM, audit_info);
671 		return -ENOMEM;
672 	}
673 
674 	INIT_LIST_HEAD(&entry->list);
675 
676 	p = strsep(&rule, "\n");
677 	len = strlen(p) + 1;
678 
679 	if (*p == '#') {
680 		kfree(entry);
681 		return len;
682 	}
683 
684 	result = ima_parse_rule(p, entry);
685 	if (result) {
686 		kfree(entry);
687 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
688 				    NULL, op, "invalid policy", result,
689 				    audit_info);
690 		return result;
691 	}
692 
693 	mutex_lock(&ima_rules_mutex);
694 	list_add_tail(&entry->list, &ima_policy_rules);
695 	mutex_unlock(&ima_rules_mutex);
696 
697 	return len;
698 }
699 
700 /* ima_delete_rules called to cleanup invalid policy */
701 void ima_delete_rules(void)
702 {
703 	struct ima_rule_entry *entry, *tmp;
704 	int i;
705 
706 	mutex_lock(&ima_rules_mutex);
707 	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
708 		for (i = 0; i < MAX_LSM_RULES; i++)
709 			kfree(entry->lsm[i].args_p);
710 
711 		list_del(&entry->list);
712 		kfree(entry);
713 	}
714 	mutex_unlock(&ima_rules_mutex);
715 }
716