1 /* auditfilter.c -- filtering of audit events
2  *
3  * Copyright 2003-2004 Red Hat, Inc.
4  * Copyright 2005 Hewlett-Packard Development Company, L.P.
5  * Copyright 2005 IBM Corporation
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/audit.h>
24 #include <linux/kthread.h>
25 #include <linux/mutex.h>
26 #include <linux/fs.h>
27 #include <linux/namei.h>
28 #include <linux/netlink.h>
29 #include <linux/sched.h>
30 #include <linux/slab.h>
31 #include <linux/security.h>
32 #include "audit.h"
33 
34 /*
35  * Locking model:
36  *
37  * audit_filter_mutex:
38  * 		Synchronizes writes and blocking reads of audit's filterlist
39  * 		data.  Rcu is used to traverse the filterlist and access
40  * 		contents of structs audit_entry, audit_watch and opaque
41  * 		LSM rules during filtering.  If modified, these structures
42  * 		must be copied and replace their counterparts in the filterlist.
43  * 		An audit_parent struct is not accessed during filtering, so may
44  * 		be written directly provided audit_filter_mutex is held.
45  */
46 
47 /* Audit filter lists, defined in <linux/audit.h> */
48 struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
49 	LIST_HEAD_INIT(audit_filter_list[0]),
50 	LIST_HEAD_INIT(audit_filter_list[1]),
51 	LIST_HEAD_INIT(audit_filter_list[2]),
52 	LIST_HEAD_INIT(audit_filter_list[3]),
53 	LIST_HEAD_INIT(audit_filter_list[4]),
54 	LIST_HEAD_INIT(audit_filter_list[5]),
55 #if AUDIT_NR_FILTERS != 6
56 #error Fix audit_filter_list initialiser
57 #endif
58 };
59 static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
60 	LIST_HEAD_INIT(audit_rules_list[0]),
61 	LIST_HEAD_INIT(audit_rules_list[1]),
62 	LIST_HEAD_INIT(audit_rules_list[2]),
63 	LIST_HEAD_INIT(audit_rules_list[3]),
64 	LIST_HEAD_INIT(audit_rules_list[4]),
65 	LIST_HEAD_INIT(audit_rules_list[5]),
66 };
67 
68 DEFINE_MUTEX(audit_filter_mutex);
69 
audit_free_rule(struct audit_entry * e)70 static inline void audit_free_rule(struct audit_entry *e)
71 {
72 	int i;
73 	struct audit_krule *erule = &e->rule;
74 
75 	/* some rules don't have associated watches */
76 	if (erule->watch)
77 		audit_put_watch(erule->watch);
78 	if (erule->fields)
79 		for (i = 0; i < erule->field_count; i++) {
80 			struct audit_field *f = &erule->fields[i];
81 			kfree(f->lsm_str);
82 			security_audit_rule_free(f->lsm_rule);
83 		}
84 	kfree(erule->fields);
85 	kfree(erule->filterkey);
86 	kfree(e);
87 }
88 
audit_free_rule_rcu(struct rcu_head * head)89 void audit_free_rule_rcu(struct rcu_head *head)
90 {
91 	struct audit_entry *e = container_of(head, struct audit_entry, rcu);
92 	audit_free_rule(e);
93 }
94 
95 /* Initialize an audit filterlist entry. */
audit_init_entry(u32 field_count)96 static inline struct audit_entry *audit_init_entry(u32 field_count)
97 {
98 	struct audit_entry *entry;
99 	struct audit_field *fields;
100 
101 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
102 	if (unlikely(!entry))
103 		return NULL;
104 
105 	fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
106 	if (unlikely(!fields)) {
107 		kfree(entry);
108 		return NULL;
109 	}
110 	entry->rule.fields = fields;
111 
112 	return entry;
113 }
114 
115 /* Unpack a filter field's string representation from user-space
116  * buffer. */
audit_unpack_string(void ** bufp,size_t * remain,size_t len)117 char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
118 {
119 	char *str;
120 
121 	if (!*bufp || (len == 0) || (len > *remain))
122 		return ERR_PTR(-EINVAL);
123 
124 	/* Of the currently implemented string fields, PATH_MAX
125 	 * defines the longest valid length.
126 	 */
127 	if (len > PATH_MAX)
128 		return ERR_PTR(-ENAMETOOLONG);
129 
130 	str = kmalloc(len + 1, GFP_KERNEL);
131 	if (unlikely(!str))
132 		return ERR_PTR(-ENOMEM);
133 
134 	memcpy(str, *bufp, len);
135 	str[len] = 0;
136 	*bufp += len;
137 	*remain -= len;
138 
139 	return str;
140 }
141 
142 /* Translate an inode field to kernel respresentation. */
audit_to_inode(struct audit_krule * krule,struct audit_field * f)143 static inline int audit_to_inode(struct audit_krule *krule,
144 				 struct audit_field *f)
145 {
146 	if (krule->listnr != AUDIT_FILTER_EXIT ||
147 	    krule->watch || krule->inode_f || krule->tree ||
148 	    (f->op != Audit_equal && f->op != Audit_not_equal))
149 		return -EINVAL;
150 
151 	krule->inode_f = f;
152 	return 0;
153 }
154 
155 static __u32 *classes[AUDIT_SYSCALL_CLASSES];
156 
audit_register_class(int class,unsigned * list)157 int __init audit_register_class(int class, unsigned *list)
158 {
159 	__u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
160 	if (!p)
161 		return -ENOMEM;
162 	while (*list != ~0U) {
163 		unsigned n = *list++;
164 		if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
165 			kfree(p);
166 			return -EINVAL;
167 		}
168 		p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
169 	}
170 	if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
171 		kfree(p);
172 		return -EINVAL;
173 	}
174 	classes[class] = p;
175 	return 0;
176 }
177 
audit_match_class(int class,unsigned syscall)178 int audit_match_class(int class, unsigned syscall)
179 {
180 	if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
181 		return 0;
182 	if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
183 		return 0;
184 	return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
185 }
186 
187 #ifdef CONFIG_AUDITSYSCALL
audit_match_class_bits(int class,u32 * mask)188 static inline int audit_match_class_bits(int class, u32 *mask)
189 {
190 	int i;
191 
192 	if (classes[class]) {
193 		for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
194 			if (mask[i] & classes[class][i])
195 				return 0;
196 	}
197 	return 1;
198 }
199 
audit_match_signal(struct audit_entry * entry)200 static int audit_match_signal(struct audit_entry *entry)
201 {
202 	struct audit_field *arch = entry->rule.arch_f;
203 
204 	if (!arch) {
205 		/* When arch is unspecified, we must check both masks on biarch
206 		 * as syscall number alone is ambiguous. */
207 		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
208 					       entry->rule.mask) &&
209 			audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
210 					       entry->rule.mask));
211 	}
212 
213 	switch(audit_classify_arch(arch->val)) {
214 	case 0: /* native */
215 		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
216 					       entry->rule.mask));
217 	case 1: /* 32bit on biarch */
218 		return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
219 					       entry->rule.mask));
220 	default:
221 		return 1;
222 	}
223 }
224 #endif
225 
226 /* Common user-space to kernel rule translation. */
audit_to_entry_common(struct audit_rule * rule)227 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
228 {
229 	unsigned listnr;
230 	struct audit_entry *entry;
231 	int i, err;
232 
233 	err = -EINVAL;
234 	listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
235 	switch(listnr) {
236 	default:
237 		goto exit_err;
238 #ifdef CONFIG_AUDITSYSCALL
239 	case AUDIT_FILTER_ENTRY:
240 		if (rule->action == AUDIT_ALWAYS)
241 			goto exit_err;
242 	case AUDIT_FILTER_EXIT:
243 	case AUDIT_FILTER_TASK:
244 #endif
245 	case AUDIT_FILTER_USER:
246 	case AUDIT_FILTER_TYPE:
247 		;
248 	}
249 	if (unlikely(rule->action == AUDIT_POSSIBLE)) {
250 		printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n");
251 		goto exit_err;
252 	}
253 	if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
254 		goto exit_err;
255 	if (rule->field_count > AUDIT_MAX_FIELDS)
256 		goto exit_err;
257 
258 	err = -ENOMEM;
259 	entry = audit_init_entry(rule->field_count);
260 	if (!entry)
261 		goto exit_err;
262 
263 	entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
264 	entry->rule.listnr = listnr;
265 	entry->rule.action = rule->action;
266 	entry->rule.field_count = rule->field_count;
267 
268 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
269 		entry->rule.mask[i] = rule->mask[i];
270 
271 	for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
272 		int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
273 		__u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
274 		__u32 *class;
275 
276 		if (!(*p & AUDIT_BIT(bit)))
277 			continue;
278 		*p &= ~AUDIT_BIT(bit);
279 		class = classes[i];
280 		if (class) {
281 			int j;
282 			for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
283 				entry->rule.mask[j] |= class[j];
284 		}
285 	}
286 
287 	return entry;
288 
289 exit_err:
290 	return ERR_PTR(err);
291 }
292 
293 static u32 audit_ops[] =
294 {
295 	[Audit_equal] = AUDIT_EQUAL,
296 	[Audit_not_equal] = AUDIT_NOT_EQUAL,
297 	[Audit_bitmask] = AUDIT_BIT_MASK,
298 	[Audit_bittest] = AUDIT_BIT_TEST,
299 	[Audit_lt] = AUDIT_LESS_THAN,
300 	[Audit_gt] = AUDIT_GREATER_THAN,
301 	[Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
302 	[Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
303 };
304 
audit_to_op(u32 op)305 static u32 audit_to_op(u32 op)
306 {
307 	u32 n;
308 	for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
309 		;
310 	return n;
311 }
312 
313 
314 /* Translate struct audit_rule to kernel's rule respresentation.
315  * Exists for backward compatibility with userspace. */
audit_rule_to_entry(struct audit_rule * rule)316 static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
317 {
318 	struct audit_entry *entry;
319 	int err = 0;
320 	int i;
321 
322 	entry = audit_to_entry_common(rule);
323 	if (IS_ERR(entry))
324 		goto exit_nofree;
325 
326 	for (i = 0; i < rule->field_count; i++) {
327 		struct audit_field *f = &entry->rule.fields[i];
328 		u32 n;
329 
330 		n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
331 
332 		/* Support for legacy operators where
333 		 * AUDIT_NEGATE bit signifies != and otherwise assumes == */
334 		if (n & AUDIT_NEGATE)
335 			f->op = Audit_not_equal;
336 		else if (!n)
337 			f->op = Audit_equal;
338 		else
339 			f->op = audit_to_op(n);
340 
341 		entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1;
342 
343 		f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
344 		f->val = rule->values[i];
345 
346 		err = -EINVAL;
347 		if (f->op == Audit_bad)
348 			goto exit_free;
349 
350 		switch(f->type) {
351 		default:
352 			goto exit_free;
353 		case AUDIT_PID:
354 		case AUDIT_UID:
355 		case AUDIT_EUID:
356 		case AUDIT_SUID:
357 		case AUDIT_FSUID:
358 		case AUDIT_GID:
359 		case AUDIT_EGID:
360 		case AUDIT_SGID:
361 		case AUDIT_FSGID:
362 		case AUDIT_LOGINUID:
363 		case AUDIT_PERS:
364 		case AUDIT_MSGTYPE:
365 		case AUDIT_PPID:
366 		case AUDIT_DEVMAJOR:
367 		case AUDIT_DEVMINOR:
368 		case AUDIT_EXIT:
369 		case AUDIT_SUCCESS:
370 			/* bit ops are only useful on syscall args */
371 			if (f->op == Audit_bitmask || f->op == Audit_bittest)
372 				goto exit_free;
373 			break;
374 		case AUDIT_ARG0:
375 		case AUDIT_ARG1:
376 		case AUDIT_ARG2:
377 		case AUDIT_ARG3:
378 			break;
379 		/* arch is only allowed to be = or != */
380 		case AUDIT_ARCH:
381 			if (f->op != Audit_not_equal && f->op != Audit_equal)
382 				goto exit_free;
383 			entry->rule.arch_f = f;
384 			break;
385 		case AUDIT_PERM:
386 			if (f->val & ~15)
387 				goto exit_free;
388 			break;
389 		case AUDIT_FILETYPE:
390 			if (f->val & ~S_IFMT)
391 				goto exit_free;
392 			break;
393 		case AUDIT_INODE:
394 			err = audit_to_inode(&entry->rule, f);
395 			if (err)
396 				goto exit_free;
397 			break;
398 		}
399 	}
400 
401 	if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
402 		entry->rule.inode_f = NULL;
403 
404 exit_nofree:
405 	return entry;
406 
407 exit_free:
408 	audit_free_rule(entry);
409 	return ERR_PTR(err);
410 }
411 
412 /* Translate struct audit_rule_data to kernel's rule respresentation. */
audit_data_to_entry(struct audit_rule_data * data,size_t datasz)413 static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
414 					       size_t datasz)
415 {
416 	int err = 0;
417 	struct audit_entry *entry;
418 	void *bufp;
419 	size_t remain = datasz - sizeof(struct audit_rule_data);
420 	int i;
421 	char *str;
422 
423 	entry = audit_to_entry_common((struct audit_rule *)data);
424 	if (IS_ERR(entry))
425 		goto exit_nofree;
426 
427 	bufp = data->buf;
428 	entry->rule.vers_ops = 2;
429 	for (i = 0; i < data->field_count; i++) {
430 		struct audit_field *f = &entry->rule.fields[i];
431 
432 		err = -EINVAL;
433 
434 		f->op = audit_to_op(data->fieldflags[i]);
435 		if (f->op == Audit_bad)
436 			goto exit_free;
437 
438 		f->type = data->fields[i];
439 		f->val = data->values[i];
440 		f->lsm_str = NULL;
441 		f->lsm_rule = NULL;
442 		switch(f->type) {
443 		case AUDIT_PID:
444 		case AUDIT_UID:
445 		case AUDIT_EUID:
446 		case AUDIT_SUID:
447 		case AUDIT_FSUID:
448 		case AUDIT_GID:
449 		case AUDIT_EGID:
450 		case AUDIT_SGID:
451 		case AUDIT_FSGID:
452 		case AUDIT_LOGINUID:
453 		case AUDIT_PERS:
454 		case AUDIT_MSGTYPE:
455 		case AUDIT_PPID:
456 		case AUDIT_DEVMAJOR:
457 		case AUDIT_DEVMINOR:
458 		case AUDIT_EXIT:
459 		case AUDIT_SUCCESS:
460 		case AUDIT_ARG0:
461 		case AUDIT_ARG1:
462 		case AUDIT_ARG2:
463 		case AUDIT_ARG3:
464 		case AUDIT_OBJ_UID:
465 		case AUDIT_OBJ_GID:
466 			break;
467 		case AUDIT_ARCH:
468 			entry->rule.arch_f = f;
469 			break;
470 		case AUDIT_SUBJ_USER:
471 		case AUDIT_SUBJ_ROLE:
472 		case AUDIT_SUBJ_TYPE:
473 		case AUDIT_SUBJ_SEN:
474 		case AUDIT_SUBJ_CLR:
475 		case AUDIT_OBJ_USER:
476 		case AUDIT_OBJ_ROLE:
477 		case AUDIT_OBJ_TYPE:
478 		case AUDIT_OBJ_LEV_LOW:
479 		case AUDIT_OBJ_LEV_HIGH:
480 			str = audit_unpack_string(&bufp, &remain, f->val);
481 			if (IS_ERR(str))
482 				goto exit_free;
483 			entry->rule.buflen += f->val;
484 
485 			err = security_audit_rule_init(f->type, f->op, str,
486 						       (void **)&f->lsm_rule);
487 			/* Keep currently invalid fields around in case they
488 			 * become valid after a policy reload. */
489 			if (err == -EINVAL) {
490 				printk(KERN_WARNING "audit rule for LSM "
491 				       "\'%s\' is invalid\n",  str);
492 				err = 0;
493 			}
494 			if (err) {
495 				kfree(str);
496 				goto exit_free;
497 			} else
498 				f->lsm_str = str;
499 			break;
500 		case AUDIT_WATCH:
501 			str = audit_unpack_string(&bufp, &remain, f->val);
502 			if (IS_ERR(str))
503 				goto exit_free;
504 			entry->rule.buflen += f->val;
505 
506 			err = audit_to_watch(&entry->rule, str, f->val, f->op);
507 			if (err) {
508 				kfree(str);
509 				goto exit_free;
510 			}
511 			break;
512 		case AUDIT_DIR:
513 			str = audit_unpack_string(&bufp, &remain, f->val);
514 			if (IS_ERR(str))
515 				goto exit_free;
516 			entry->rule.buflen += f->val;
517 
518 			err = audit_make_tree(&entry->rule, str, f->op);
519 			kfree(str);
520 			if (err)
521 				goto exit_free;
522 			break;
523 		case AUDIT_INODE:
524 			err = audit_to_inode(&entry->rule, f);
525 			if (err)
526 				goto exit_free;
527 			break;
528 		case AUDIT_FILTERKEY:
529 			if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
530 				goto exit_free;
531 			str = audit_unpack_string(&bufp, &remain, f->val);
532 			if (IS_ERR(str))
533 				goto exit_free;
534 			entry->rule.buflen += f->val;
535 			entry->rule.filterkey = str;
536 			break;
537 		case AUDIT_PERM:
538 			if (f->val & ~15)
539 				goto exit_free;
540 			break;
541 		case AUDIT_FILETYPE:
542 			if (f->val & ~S_IFMT)
543 				goto exit_free;
544 			break;
545 		case AUDIT_FIELD_COMPARE:
546 			if (f->val > AUDIT_MAX_FIELD_COMPARE)
547 				goto exit_free;
548 			break;
549 		default:
550 			goto exit_free;
551 		}
552 	}
553 
554 	if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
555 		entry->rule.inode_f = NULL;
556 
557 exit_nofree:
558 	return entry;
559 
560 exit_free:
561 	audit_free_rule(entry);
562 	return ERR_PTR(err);
563 }
564 
565 /* Pack a filter field's string representation into data block. */
audit_pack_string(void ** bufp,const char * str)566 static inline size_t audit_pack_string(void **bufp, const char *str)
567 {
568 	size_t len = strlen(str);
569 
570 	memcpy(*bufp, str, len);
571 	*bufp += len;
572 
573 	return len;
574 }
575 
576 /* Translate kernel rule respresentation to struct audit_rule.
577  * Exists for backward compatibility with userspace. */
audit_krule_to_rule(struct audit_krule * krule)578 static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
579 {
580 	struct audit_rule *rule;
581 	int i;
582 
583 	rule = kzalloc(sizeof(*rule), GFP_KERNEL);
584 	if (unlikely(!rule))
585 		return NULL;
586 
587 	rule->flags = krule->flags | krule->listnr;
588 	rule->action = krule->action;
589 	rule->field_count = krule->field_count;
590 	for (i = 0; i < rule->field_count; i++) {
591 		rule->values[i] = krule->fields[i].val;
592 		rule->fields[i] = krule->fields[i].type;
593 
594 		if (krule->vers_ops == 1) {
595 			if (krule->fields[i].op == Audit_not_equal)
596 				rule->fields[i] |= AUDIT_NEGATE;
597 		} else {
598 			rule->fields[i] |= audit_ops[krule->fields[i].op];
599 		}
600 	}
601 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];
602 
603 	return rule;
604 }
605 
606 /* Translate kernel rule respresentation to struct audit_rule_data. */
audit_krule_to_data(struct audit_krule * krule)607 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
608 {
609 	struct audit_rule_data *data;
610 	void *bufp;
611 	int i;
612 
613 	data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
614 	if (unlikely(!data))
615 		return NULL;
616 	memset(data, 0, sizeof(*data));
617 
618 	data->flags = krule->flags | krule->listnr;
619 	data->action = krule->action;
620 	data->field_count = krule->field_count;
621 	bufp = data->buf;
622 	for (i = 0; i < data->field_count; i++) {
623 		struct audit_field *f = &krule->fields[i];
624 
625 		data->fields[i] = f->type;
626 		data->fieldflags[i] = audit_ops[f->op];
627 		switch(f->type) {
628 		case AUDIT_SUBJ_USER:
629 		case AUDIT_SUBJ_ROLE:
630 		case AUDIT_SUBJ_TYPE:
631 		case AUDIT_SUBJ_SEN:
632 		case AUDIT_SUBJ_CLR:
633 		case AUDIT_OBJ_USER:
634 		case AUDIT_OBJ_ROLE:
635 		case AUDIT_OBJ_TYPE:
636 		case AUDIT_OBJ_LEV_LOW:
637 		case AUDIT_OBJ_LEV_HIGH:
638 			data->buflen += data->values[i] =
639 				audit_pack_string(&bufp, f->lsm_str);
640 			break;
641 		case AUDIT_WATCH:
642 			data->buflen += data->values[i] =
643 				audit_pack_string(&bufp,
644 						  audit_watch_path(krule->watch));
645 			break;
646 		case AUDIT_DIR:
647 			data->buflen += data->values[i] =
648 				audit_pack_string(&bufp,
649 						  audit_tree_path(krule->tree));
650 			break;
651 		case AUDIT_FILTERKEY:
652 			data->buflen += data->values[i] =
653 				audit_pack_string(&bufp, krule->filterkey);
654 			break;
655 		default:
656 			data->values[i] = f->val;
657 		}
658 	}
659 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
660 
661 	return data;
662 }
663 
664 /* Compare two rules in kernel format.  Considered success if rules
665  * don't match. */
audit_compare_rule(struct audit_krule * a,struct audit_krule * b)666 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
667 {
668 	int i;
669 
670 	if (a->flags != b->flags ||
671 	    a->listnr != b->listnr ||
672 	    a->action != b->action ||
673 	    a->field_count != b->field_count)
674 		return 1;
675 
676 	for (i = 0; i < a->field_count; i++) {
677 		if (a->fields[i].type != b->fields[i].type ||
678 		    a->fields[i].op != b->fields[i].op)
679 			return 1;
680 
681 		switch(a->fields[i].type) {
682 		case AUDIT_SUBJ_USER:
683 		case AUDIT_SUBJ_ROLE:
684 		case AUDIT_SUBJ_TYPE:
685 		case AUDIT_SUBJ_SEN:
686 		case AUDIT_SUBJ_CLR:
687 		case AUDIT_OBJ_USER:
688 		case AUDIT_OBJ_ROLE:
689 		case AUDIT_OBJ_TYPE:
690 		case AUDIT_OBJ_LEV_LOW:
691 		case AUDIT_OBJ_LEV_HIGH:
692 			if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
693 				return 1;
694 			break;
695 		case AUDIT_WATCH:
696 			if (strcmp(audit_watch_path(a->watch),
697 				   audit_watch_path(b->watch)))
698 				return 1;
699 			break;
700 		case AUDIT_DIR:
701 			if (strcmp(audit_tree_path(a->tree),
702 				   audit_tree_path(b->tree)))
703 				return 1;
704 			break;
705 		case AUDIT_FILTERKEY:
706 			/* both filterkeys exist based on above type compare */
707 			if (strcmp(a->filterkey, b->filterkey))
708 				return 1;
709 			break;
710 		default:
711 			if (a->fields[i].val != b->fields[i].val)
712 				return 1;
713 		}
714 	}
715 
716 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
717 		if (a->mask[i] != b->mask[i])
718 			return 1;
719 
720 	return 0;
721 }
722 
723 /* Duplicate LSM field information.  The lsm_rule is opaque, so must be
724  * re-initialized. */
audit_dupe_lsm_field(struct audit_field * df,struct audit_field * sf)725 static inline int audit_dupe_lsm_field(struct audit_field *df,
726 					   struct audit_field *sf)
727 {
728 	int ret = 0;
729 	char *lsm_str;
730 
731 	/* our own copy of lsm_str */
732 	lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
733 	if (unlikely(!lsm_str))
734 		return -ENOMEM;
735 	df->lsm_str = lsm_str;
736 
737 	/* our own (refreshed) copy of lsm_rule */
738 	ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
739 				       (void **)&df->lsm_rule);
740 	/* Keep currently invalid fields around in case they
741 	 * become valid after a policy reload. */
742 	if (ret == -EINVAL) {
743 		printk(KERN_WARNING "audit rule for LSM \'%s\' is "
744 		       "invalid\n", df->lsm_str);
745 		ret = 0;
746 	}
747 
748 	return ret;
749 }
750 
751 /* Duplicate an audit rule.  This will be a deep copy with the exception
752  * of the watch - that pointer is carried over.  The LSM specific fields
753  * will be updated in the copy.  The point is to be able to replace the old
754  * rule with the new rule in the filterlist, then free the old rule.
755  * The rlist element is undefined; list manipulations are handled apart from
756  * the initial copy. */
audit_dupe_rule(struct audit_krule * old)757 struct audit_entry *audit_dupe_rule(struct audit_krule *old)
758 {
759 	u32 fcount = old->field_count;
760 	struct audit_entry *entry;
761 	struct audit_krule *new;
762 	char *fk;
763 	int i, err = 0;
764 
765 	entry = audit_init_entry(fcount);
766 	if (unlikely(!entry))
767 		return ERR_PTR(-ENOMEM);
768 
769 	new = &entry->rule;
770 	new->vers_ops = old->vers_ops;
771 	new->flags = old->flags;
772 	new->listnr = old->listnr;
773 	new->action = old->action;
774 	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
775 		new->mask[i] = old->mask[i];
776 	new->prio = old->prio;
777 	new->buflen = old->buflen;
778 	new->inode_f = old->inode_f;
779 	new->field_count = old->field_count;
780 
781 	/*
782 	 * note that we are OK with not refcounting here; audit_match_tree()
783 	 * never dereferences tree and we can't get false positives there
784 	 * since we'd have to have rule gone from the list *and* removed
785 	 * before the chunks found by lookup had been allocated, i.e. before
786 	 * the beginning of list scan.
787 	 */
788 	new->tree = old->tree;
789 	memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
790 
791 	/* deep copy this information, updating the lsm_rule fields, because
792 	 * the originals will all be freed when the old rule is freed. */
793 	for (i = 0; i < fcount; i++) {
794 		switch (new->fields[i].type) {
795 		case AUDIT_SUBJ_USER:
796 		case AUDIT_SUBJ_ROLE:
797 		case AUDIT_SUBJ_TYPE:
798 		case AUDIT_SUBJ_SEN:
799 		case AUDIT_SUBJ_CLR:
800 		case AUDIT_OBJ_USER:
801 		case AUDIT_OBJ_ROLE:
802 		case AUDIT_OBJ_TYPE:
803 		case AUDIT_OBJ_LEV_LOW:
804 		case AUDIT_OBJ_LEV_HIGH:
805 			err = audit_dupe_lsm_field(&new->fields[i],
806 						       &old->fields[i]);
807 			break;
808 		case AUDIT_FILTERKEY:
809 			fk = kstrdup(old->filterkey, GFP_KERNEL);
810 			if (unlikely(!fk))
811 				err = -ENOMEM;
812 			else
813 				new->filterkey = fk;
814 		}
815 		if (err) {
816 			audit_free_rule(entry);
817 			return ERR_PTR(err);
818 		}
819 	}
820 
821 	if (old->watch) {
822 		audit_get_watch(old->watch);
823 		new->watch = old->watch;
824 	}
825 
826 	return entry;
827 }
828 
829 /* Find an existing audit rule.
830  * Caller must hold audit_filter_mutex to prevent stale rule data. */
audit_find_rule(struct audit_entry * entry,struct list_head ** p)831 static struct audit_entry *audit_find_rule(struct audit_entry *entry,
832 					   struct list_head **p)
833 {
834 	struct audit_entry *e, *found = NULL;
835 	struct list_head *list;
836 	int h;
837 
838 	if (entry->rule.inode_f) {
839 		h = audit_hash_ino(entry->rule.inode_f->val);
840 		*p = list = &audit_inode_hash[h];
841 	} else if (entry->rule.watch) {
842 		/* we don't know the inode number, so must walk entire hash */
843 		for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
844 			list = &audit_inode_hash[h];
845 			list_for_each_entry(e, list, list)
846 				if (!audit_compare_rule(&entry->rule, &e->rule)) {
847 					found = e;
848 					goto out;
849 				}
850 		}
851 		goto out;
852 	} else {
853 		*p = list = &audit_filter_list[entry->rule.listnr];
854 	}
855 
856 	list_for_each_entry(e, list, list)
857 		if (!audit_compare_rule(&entry->rule, &e->rule)) {
858 			found = e;
859 			goto out;
860 		}
861 
862 out:
863 	return found;
864 }
865 
866 static u64 prio_low = ~0ULL/2;
867 static u64 prio_high = ~0ULL/2 - 1;
868 
869 /* Add rule to given filterlist if not a duplicate. */
audit_add_rule(struct audit_entry * entry)870 static inline int audit_add_rule(struct audit_entry *entry)
871 {
872 	struct audit_entry *e;
873 	struct audit_watch *watch = entry->rule.watch;
874 	struct audit_tree *tree = entry->rule.tree;
875 	struct list_head *list;
876 	int err;
877 #ifdef CONFIG_AUDITSYSCALL
878 	int dont_count = 0;
879 
880 	/* If either of these, don't count towards total */
881 	if (entry->rule.listnr == AUDIT_FILTER_USER ||
882 		entry->rule.listnr == AUDIT_FILTER_TYPE)
883 		dont_count = 1;
884 #endif
885 
886 	mutex_lock(&audit_filter_mutex);
887 	e = audit_find_rule(entry, &list);
888 	if (e) {
889 		mutex_unlock(&audit_filter_mutex);
890 		err = -EEXIST;
891 		/* normally audit_add_tree_rule() will free it on failure */
892 		if (tree)
893 			audit_put_tree(tree);
894 		goto error;
895 	}
896 
897 	if (watch) {
898 		/* audit_filter_mutex is dropped and re-taken during this call */
899 		err = audit_add_watch(&entry->rule, &list);
900 		if (err) {
901 			mutex_unlock(&audit_filter_mutex);
902 			goto error;
903 		}
904 	}
905 	if (tree) {
906 		err = audit_add_tree_rule(&entry->rule);
907 		if (err) {
908 			mutex_unlock(&audit_filter_mutex);
909 			goto error;
910 		}
911 	}
912 
913 	entry->rule.prio = ~0ULL;
914 	if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
915 		if (entry->rule.flags & AUDIT_FILTER_PREPEND)
916 			entry->rule.prio = ++prio_high;
917 		else
918 			entry->rule.prio = --prio_low;
919 	}
920 
921 	if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
922 		list_add(&entry->rule.list,
923 			 &audit_rules_list[entry->rule.listnr]);
924 		list_add_rcu(&entry->list, list);
925 		entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
926 	} else {
927 		list_add_tail(&entry->rule.list,
928 			      &audit_rules_list[entry->rule.listnr]);
929 		list_add_tail_rcu(&entry->list, list);
930 	}
931 #ifdef CONFIG_AUDITSYSCALL
932 	if (!dont_count)
933 		audit_n_rules++;
934 
935 	if (!audit_match_signal(entry))
936 		audit_signals++;
937 #endif
938 	mutex_unlock(&audit_filter_mutex);
939 
940  	return 0;
941 
942 error:
943 	if (watch)
944 		audit_put_watch(watch); /* tmp watch, matches initial get */
945 	return err;
946 }
947 
948 /* Remove an existing rule from filterlist. */
audit_del_rule(struct audit_entry * entry)949 static inline int audit_del_rule(struct audit_entry *entry)
950 {
951 	struct audit_entry  *e;
952 	struct audit_watch *watch = entry->rule.watch;
953 	struct audit_tree *tree = entry->rule.tree;
954 	struct list_head *list;
955 	int ret = 0;
956 #ifdef CONFIG_AUDITSYSCALL
957 	int dont_count = 0;
958 
959 	/* If either of these, don't count towards total */
960 	if (entry->rule.listnr == AUDIT_FILTER_USER ||
961 		entry->rule.listnr == AUDIT_FILTER_TYPE)
962 		dont_count = 1;
963 #endif
964 
965 	mutex_lock(&audit_filter_mutex);
966 	e = audit_find_rule(entry, &list);
967 	if (!e) {
968 		mutex_unlock(&audit_filter_mutex);
969 		ret = -ENOENT;
970 		goto out;
971 	}
972 
973 	if (e->rule.watch)
974 		audit_remove_watch_rule(&e->rule);
975 
976 	if (e->rule.tree)
977 		audit_remove_tree_rule(&e->rule);
978 
979 	list_del_rcu(&e->list);
980 	list_del(&e->rule.list);
981 	call_rcu(&e->rcu, audit_free_rule_rcu);
982 
983 #ifdef CONFIG_AUDITSYSCALL
984 	if (!dont_count)
985 		audit_n_rules--;
986 
987 	if (!audit_match_signal(entry))
988 		audit_signals--;
989 #endif
990 	mutex_unlock(&audit_filter_mutex);
991 
992 out:
993 	if (watch)
994 		audit_put_watch(watch); /* match initial get */
995 	if (tree)
996 		audit_put_tree(tree);	/* that's the temporary one */
997 
998 	return ret;
999 }
1000 
1001 /* List rules using struct audit_rule.  Exists for backward
1002  * compatibility with userspace. */
audit_list(int pid,int seq,struct sk_buff_head * q)1003 static void audit_list(int pid, int seq, struct sk_buff_head *q)
1004 {
1005 	struct sk_buff *skb;
1006 	struct audit_krule *r;
1007 	int i;
1008 
1009 	/* This is a blocking read, so use audit_filter_mutex instead of rcu
1010 	 * iterator to sync with list writers. */
1011 	for (i=0; i<AUDIT_NR_FILTERS; i++) {
1012 		list_for_each_entry(r, &audit_rules_list[i], list) {
1013 			struct audit_rule *rule;
1014 
1015 			rule = audit_krule_to_rule(r);
1016 			if (unlikely(!rule))
1017 				break;
1018 			skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
1019 					 rule, sizeof(*rule));
1020 			if (skb)
1021 				skb_queue_tail(q, skb);
1022 			kfree(rule);
1023 		}
1024 	}
1025 	skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
1026 	if (skb)
1027 		skb_queue_tail(q, skb);
1028 }
1029 
1030 /* List rules using struct audit_rule_data. */
audit_list_rules(int pid,int seq,struct sk_buff_head * q)1031 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
1032 {
1033 	struct sk_buff *skb;
1034 	struct audit_krule *r;
1035 	int i;
1036 
1037 	/* This is a blocking read, so use audit_filter_mutex instead of rcu
1038 	 * iterator to sync with list writers. */
1039 	for (i=0; i<AUDIT_NR_FILTERS; i++) {
1040 		list_for_each_entry(r, &audit_rules_list[i], list) {
1041 			struct audit_rule_data *data;
1042 
1043 			data = audit_krule_to_data(r);
1044 			if (unlikely(!data))
1045 				break;
1046 			skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
1047 					 data, sizeof(*data) + data->buflen);
1048 			if (skb)
1049 				skb_queue_tail(q, skb);
1050 			kfree(data);
1051 		}
1052 	}
1053 	skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1054 	if (skb)
1055 		skb_queue_tail(q, skb);
1056 }
1057 
1058 /* Log rule additions and removals */
audit_log_rule_change(uid_t loginuid,u32 sessionid,u32 sid,char * action,struct audit_krule * rule,int res)1059 static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid,
1060 				  char *action, struct audit_krule *rule,
1061 				  int res)
1062 {
1063 	struct audit_buffer *ab;
1064 
1065 	if (!audit_enabled)
1066 		return;
1067 
1068 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1069 	if (!ab)
1070 		return;
1071 	audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid);
1072 	if (sid) {
1073 		char *ctx = NULL;
1074 		u32 len;
1075 		if (security_secid_to_secctx(sid, &ctx, &len))
1076 			audit_log_format(ab, " ssid=%u", sid);
1077 		else {
1078 			audit_log_format(ab, " subj=%s", ctx);
1079 			security_release_secctx(ctx, len);
1080 		}
1081 	}
1082 	audit_log_format(ab, " op=");
1083 	audit_log_string(ab, action);
1084 	audit_log_key(ab, rule->filterkey);
1085 	audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1086 	audit_log_end(ab);
1087 }
1088 
1089 /**
1090  * audit_receive_filter - apply all rules to the specified message type
1091  * @type: audit message type
1092  * @pid: target pid for netlink audit messages
1093  * @uid: target uid for netlink audit messages
1094  * @seq: netlink audit message sequence (serial) number
1095  * @data: payload data
1096  * @datasz: size of payload data
1097  * @loginuid: loginuid of sender
1098  * @sessionid: sessionid for netlink audit message
1099  * @sid: SE Linux Security ID of sender
1100  */
audit_receive_filter(int type,int pid,int uid,int seq,void * data,size_t datasz,uid_t loginuid,u32 sessionid,u32 sid)1101 int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
1102 			 size_t datasz, uid_t loginuid, u32 sessionid, u32 sid)
1103 {
1104 	struct task_struct *tsk;
1105 	struct audit_netlink_list *dest;
1106 	int err = 0;
1107 	struct audit_entry *entry;
1108 
1109 	switch (type) {
1110 	case AUDIT_LIST:
1111 	case AUDIT_LIST_RULES:
1112 		/* We can't just spew out the rules here because we might fill
1113 		 * the available socket buffer space and deadlock waiting for
1114 		 * auditctl to read from it... which isn't ever going to
1115 		 * happen if we're actually running in the context of auditctl
1116 		 * trying to _send_ the stuff */
1117 
1118 		dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1119 		if (!dest)
1120 			return -ENOMEM;
1121 		dest->pid = pid;
1122 		skb_queue_head_init(&dest->q);
1123 
1124 		mutex_lock(&audit_filter_mutex);
1125 		if (type == AUDIT_LIST)
1126 			audit_list(pid, seq, &dest->q);
1127 		else
1128 			audit_list_rules(pid, seq, &dest->q);
1129 		mutex_unlock(&audit_filter_mutex);
1130 
1131 		tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1132 		if (IS_ERR(tsk)) {
1133 			skb_queue_purge(&dest->q);
1134 			kfree(dest);
1135 			err = PTR_ERR(tsk);
1136 		}
1137 		break;
1138 	case AUDIT_ADD:
1139 	case AUDIT_ADD_RULE:
1140 		if (type == AUDIT_ADD)
1141 			entry = audit_rule_to_entry(data);
1142 		else
1143 			entry = audit_data_to_entry(data, datasz);
1144 		if (IS_ERR(entry))
1145 			return PTR_ERR(entry);
1146 
1147 		err = audit_add_rule(entry);
1148 		audit_log_rule_change(loginuid, sessionid, sid, "add rule",
1149 				      &entry->rule, !err);
1150 
1151 		if (err)
1152 			audit_free_rule(entry);
1153 		break;
1154 	case AUDIT_DEL:
1155 	case AUDIT_DEL_RULE:
1156 		if (type == AUDIT_DEL)
1157 			entry = audit_rule_to_entry(data);
1158 		else
1159 			entry = audit_data_to_entry(data, datasz);
1160 		if (IS_ERR(entry))
1161 			return PTR_ERR(entry);
1162 
1163 		err = audit_del_rule(entry);
1164 		audit_log_rule_change(loginuid, sessionid, sid, "remove rule",
1165 				      &entry->rule, !err);
1166 
1167 		audit_free_rule(entry);
1168 		break;
1169 	default:
1170 		return -EINVAL;
1171 	}
1172 
1173 	return err;
1174 }
1175 
audit_comparator(u32 left,u32 op,u32 right)1176 int audit_comparator(u32 left, u32 op, u32 right)
1177 {
1178 	switch (op) {
1179 	case Audit_equal:
1180 		return (left == right);
1181 	case Audit_not_equal:
1182 		return (left != right);
1183 	case Audit_lt:
1184 		return (left < right);
1185 	case Audit_le:
1186 		return (left <= right);
1187 	case Audit_gt:
1188 		return (left > right);
1189 	case Audit_ge:
1190 		return (left >= right);
1191 	case Audit_bitmask:
1192 		return (left & right);
1193 	case Audit_bittest:
1194 		return ((left & right) == right);
1195 	default:
1196 		BUG();
1197 		return 0;
1198 	}
1199 }
1200 
1201 /* Compare given dentry name with last component in given path,
1202  * return of 0 indicates a match. */
audit_compare_dname_path(const char * dname,const char * path,int * dirlen)1203 int audit_compare_dname_path(const char *dname, const char *path,
1204 			     int *dirlen)
1205 {
1206 	int dlen, plen;
1207 	const char *p;
1208 
1209 	if (!dname || !path)
1210 		return 1;
1211 
1212 	dlen = strlen(dname);
1213 	plen = strlen(path);
1214 	if (plen < dlen)
1215 		return 1;
1216 
1217 	/* disregard trailing slashes */
1218 	p = path + plen - 1;
1219 	while ((*p == '/') && (p > path))
1220 		p--;
1221 
1222 	/* find last path component */
1223 	p = p - dlen + 1;
1224 	if (p < path)
1225 		return 1;
1226 	else if (p > path) {
1227 		if (*--p != '/')
1228 			return 1;
1229 		else
1230 			p++;
1231 	}
1232 
1233 	/* return length of path's directory component */
1234 	if (dirlen)
1235 		*dirlen = p - path;
1236 	return strncmp(p, dname, dlen);
1237 }
1238 
audit_filter_user_rules(struct netlink_skb_parms * cb,struct audit_krule * rule,enum audit_state * state)1239 static int audit_filter_user_rules(struct netlink_skb_parms *cb,
1240 				   struct audit_krule *rule,
1241 				   enum audit_state *state)
1242 {
1243 	int i;
1244 
1245 	for (i = 0; i < rule->field_count; i++) {
1246 		struct audit_field *f = &rule->fields[i];
1247 		int result = 0;
1248 		u32 sid;
1249 
1250 		switch (f->type) {
1251 		case AUDIT_PID:
1252 			result = audit_comparator(cb->creds.pid, f->op, f->val);
1253 			break;
1254 		case AUDIT_UID:
1255 			result = audit_comparator(cb->creds.uid, f->op, f->val);
1256 			break;
1257 		case AUDIT_GID:
1258 			result = audit_comparator(cb->creds.gid, f->op, f->val);
1259 			break;
1260 		case AUDIT_LOGINUID:
1261 			result = audit_comparator(audit_get_loginuid(current),
1262 						  f->op, f->val);
1263 			break;
1264 		case AUDIT_SUBJ_USER:
1265 		case AUDIT_SUBJ_ROLE:
1266 		case AUDIT_SUBJ_TYPE:
1267 		case AUDIT_SUBJ_SEN:
1268 		case AUDIT_SUBJ_CLR:
1269 			if (f->lsm_rule) {
1270 				security_task_getsecid(current, &sid);
1271 				result = security_audit_rule_match(sid,
1272 								   f->type,
1273 								   f->op,
1274 								   f->lsm_rule,
1275 								   NULL);
1276 			}
1277 			break;
1278 		}
1279 
1280 		if (!result)
1281 			return 0;
1282 	}
1283 	switch (rule->action) {
1284 	case AUDIT_NEVER:    *state = AUDIT_DISABLED;	    break;
1285 	case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
1286 	}
1287 	return 1;
1288 }
1289 
audit_filter_user(struct netlink_skb_parms * cb)1290 int audit_filter_user(struct netlink_skb_parms *cb)
1291 {
1292 	enum audit_state state = AUDIT_DISABLED;
1293 	struct audit_entry *e;
1294 	int ret = 1;
1295 
1296 	rcu_read_lock();
1297 	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
1298 		if (audit_filter_user_rules(cb, &e->rule, &state)) {
1299 			if (state == AUDIT_DISABLED)
1300 				ret = 0;
1301 			break;
1302 		}
1303 	}
1304 	rcu_read_unlock();
1305 
1306 	return ret; /* Audit by default */
1307 }
1308 
audit_filter_type(int type)1309 int audit_filter_type(int type)
1310 {
1311 	struct audit_entry *e;
1312 	int result = 0;
1313 
1314 	rcu_read_lock();
1315 	if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
1316 		goto unlock_and_return;
1317 
1318 	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
1319 				list) {
1320 		int i;
1321 		for (i = 0; i < e->rule.field_count; i++) {
1322 			struct audit_field *f = &e->rule.fields[i];
1323 			if (f->type == AUDIT_MSGTYPE) {
1324 				result = audit_comparator(type, f->op, f->val);
1325 				if (!result)
1326 					break;
1327 			}
1328 		}
1329 		if (result)
1330 			goto unlock_and_return;
1331 	}
1332 unlock_and_return:
1333 	rcu_read_unlock();
1334 	return result;
1335 }
1336 
update_lsm_rule(struct audit_krule * r)1337 static int update_lsm_rule(struct audit_krule *r)
1338 {
1339 	struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1340 	struct audit_entry *nentry;
1341 	int err = 0;
1342 
1343 	if (!security_audit_rule_known(r))
1344 		return 0;
1345 
1346 	nentry = audit_dupe_rule(r);
1347 	if (IS_ERR(nentry)) {
1348 		/* save the first error encountered for the
1349 		 * return value */
1350 		err = PTR_ERR(nentry);
1351 		audit_panic("error updating LSM filters");
1352 		if (r->watch)
1353 			list_del(&r->rlist);
1354 		list_del_rcu(&entry->list);
1355 		list_del(&r->list);
1356 	} else {
1357 		if (r->watch || r->tree)
1358 			list_replace_init(&r->rlist, &nentry->rule.rlist);
1359 		list_replace_rcu(&entry->list, &nentry->list);
1360 		list_replace(&r->list, &nentry->rule.list);
1361 	}
1362 	call_rcu(&entry->rcu, audit_free_rule_rcu);
1363 
1364 	return err;
1365 }
1366 
1367 /* This function will re-initialize the lsm_rule field of all applicable rules.
1368  * It will traverse the filter lists serarching for rules that contain LSM
1369  * specific filter fields.  When such a rule is found, it is copied, the
1370  * LSM field is re-initialized, and the old rule is replaced with the
1371  * updated rule. */
audit_update_lsm_rules(void)1372 int audit_update_lsm_rules(void)
1373 {
1374 	struct audit_krule *r, *n;
1375 	int i, err = 0;
1376 
1377 	/* audit_filter_mutex synchronizes the writers */
1378 	mutex_lock(&audit_filter_mutex);
1379 
1380 	for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1381 		list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1382 			int res = update_lsm_rule(r);
1383 			if (!err)
1384 				err = res;
1385 		}
1386 	}
1387 	mutex_unlock(&audit_filter_mutex);
1388 
1389 	return err;
1390 }
1391