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On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:
[mmotm.git] / kernel / auditfilter.c
blobf5e4cae5ad8285c31de8a23342b280e63554e575
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/security.h>
31 #include "audit.h"
32
33 /*
34 * Locking model:
35 *
36 * audit_filter_mutex:
37 * Synchronizes writes and blocking reads of audit's filterlist
38 * data. Rcu is used to traverse the filterlist and access
39 * contents of structs audit_entry, audit_watch and opaque
40 * LSM rules during filtering. If modified, these structures
41 * must be copied and replace their counterparts in the filterlist.
42 * An audit_parent struct is not accessed during filtering, so may
43 * be written directly provided audit_filter_mutex is held.
44 */
45
46 /* Audit filter lists, defined in <linux/audit.h> */
47 struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
48 LIST_HEAD_INIT(audit_filter_list[0]),
49 LIST_HEAD_INIT(audit_filter_list[1]),
50 LIST_HEAD_INIT(audit_filter_list[2]),
51 LIST_HEAD_INIT(audit_filter_list[3]),
52 LIST_HEAD_INIT(audit_filter_list[4]),
53 LIST_HEAD_INIT(audit_filter_list[5]),
54 #if AUDIT_NR_FILTERS != 6
55 #error Fix audit_filter_list initialiser
56 #endif
57 };
58 static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
59 LIST_HEAD_INIT(audit_rules_list[0]),
60 LIST_HEAD_INIT(audit_rules_list[1]),
61 LIST_HEAD_INIT(audit_rules_list[2]),
62 LIST_HEAD_INIT(audit_rules_list[3]),
63 LIST_HEAD_INIT(audit_rules_list[4]),
64 LIST_HEAD_INIT(audit_rules_list[5]),
65 };
66
67 DEFINE_MUTEX(audit_filter_mutex);
68
69 static inline void audit_free_rule(struct audit_entry *e)
70 {
71 int i;
72 struct audit_krule *erule = &e->rule;
73
74 /* some rules don't have associated watches */
75 if (erule->watch)
76 audit_put_watch(erule->watch);
77 if (erule->fields)
78 for (i = 0; i < erule->field_count; i++) {
79 struct audit_field *f = &erule->fields[i];
80 kfree(f->lsm_str);
81 security_audit_rule_free(f->lsm_rule);
82 }
83 kfree(erule->fields);
84 kfree(erule->filterkey);
85 kfree(e);
86 }
87
88 void audit_free_rule_rcu(struct rcu_head *head)
89 {
90 struct audit_entry *e = container_of(head, struct audit_entry, rcu);
91 audit_free_rule(e);
92 }
93
94 /* Initialize an audit filterlist entry. */
95 static inline struct audit_entry *audit_init_entry(u32 field_count)
96 {
97 struct audit_entry *entry;
98 struct audit_field *fields;
99
100 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
101 if (unlikely(!entry))
102 return NULL;
103
104 fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
105 if (unlikely(!fields)) {
106 kfree(entry);
107 return NULL;
108 }
109 entry->rule.fields = fields;
110
111 return entry;
112 }
113
114 /* Unpack a filter field's string representation from user-space
115 * buffer. */
116 char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
117 {
118 char *str;
119
120 if (!*bufp || (len == 0) || (len > *remain))
121 return ERR_PTR(-EINVAL);
122
123 /* Of the currently implemented string fields, PATH_MAX
124 * defines the longest valid length.
125 */
126 if (len > PATH_MAX)
127 return ERR_PTR(-ENAMETOOLONG);
128
129 str = kmalloc(len + 1, GFP_KERNEL);
130 if (unlikely(!str))
131 return ERR_PTR(-ENOMEM);
132
133 memcpy(str, *bufp, len);
134 str[len] = 0;
135 *bufp += len;
136 *remain -= len;
137
138 return str;
139 }
140
141 /* Translate an inode field to kernel respresentation. */
142 static inline int audit_to_inode(struct audit_krule *krule,
143 struct audit_field *f)
144 {
145 if (krule->listnr != AUDIT_FILTER_EXIT ||
146 krule->watch || krule->inode_f || krule->tree ||
147 (f->op != Audit_equal && f->op != Audit_not_equal))
148 return -EINVAL;
149
150 krule->inode_f = f;
151 return 0;
152 }
153
154 static __u32 *classes[AUDIT_SYSCALL_CLASSES];
155
156 int __init audit_register_class(int class, unsigned *list)
157 {
158 __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
159 if (!p)
160 return -ENOMEM;
161 while (*list != ~0U) {
162 unsigned n = *list++;
163 if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
164 kfree(p);
165 return -EINVAL;
166 }
167 p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
168 }
169 if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
170 kfree(p);
171 return -EINVAL;
172 }
173 classes[class] = p;
174 return 0;
175 }
176
177 int audit_match_class(int class, unsigned syscall)
178 {
179 if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
180 return 0;
181 if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
182 return 0;
183 return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
184 }
185
186 #ifdef CONFIG_AUDITSYSCALL
187 static inline int audit_match_class_bits(int class, u32 *mask)
188 {
189 int i;
190
191 if (classes[class]) {
192 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
193 if (mask[i] & classes[class][i])
194 return 0;
195 }
196 return 1;
197 }
198
199 static int audit_match_signal(struct audit_entry *entry)
200 {
201 struct audit_field *arch = entry->rule.arch_f;
202
203 if (!arch) {
204 /* When arch is unspecified, we must check both masks on biarch
205 * as syscall number alone is ambiguous. */
206 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
207 entry->rule.mask) &&
208 audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
209 entry->rule.mask));
210 }
211
212 switch(audit_classify_arch(arch->val)) {
213 case 0: /* native */
214 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
215 entry->rule.mask));
216 case 1: /* 32bit on biarch */
217 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
218 entry->rule.mask));
219 default:
220 return 1;
221 }
222 }
223 #endif
224
225 /* Common user-space to kernel rule translation. */
226 static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
227 {
228 unsigned listnr;
229 struct audit_entry *entry;
230 int i, err;
231
232 err = -EINVAL;
233 listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
234 switch(listnr) {
235 default:
236 goto exit_err;
237 case AUDIT_FILTER_USER:
238 case AUDIT_FILTER_TYPE:
239 #ifdef CONFIG_AUDITSYSCALL
240 case AUDIT_FILTER_ENTRY:
241 case AUDIT_FILTER_EXIT:
242 case AUDIT_FILTER_TASK:
243 #endif
244 ;
245 }
246 if (unlikely(rule->action == AUDIT_POSSIBLE)) {
247 printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n");
248 goto exit_err;
249 }
250 if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
251 goto exit_err;
252 if (rule->field_count > AUDIT_MAX_FIELDS)
253 goto exit_err;
254
255 err = -ENOMEM;
256 entry = audit_init_entry(rule->field_count);
257 if (!entry)
258 goto exit_err;
259
260 entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
261 entry->rule.listnr = listnr;
262 entry->rule.action = rule->action;
263 entry->rule.field_count = rule->field_count;
264
265 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
266 entry->rule.mask[i] = rule->mask[i];
267
268 for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
269 int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
270 __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
271 __u32 *class;
272
273 if (!(*p & AUDIT_BIT(bit)))
274 continue;
275 *p &= ~AUDIT_BIT(bit);
276 class = classes[i];
277 if (class) {
278 int j;
279 for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
280 entry->rule.mask[j] |= class[j];
281 }
282 }
283
284 return entry;
285
286 exit_err:
287 return ERR_PTR(err);
288 }
289
290 static u32 audit_ops[] =
291 {
292 [Audit_equal] = AUDIT_EQUAL,
293 [Audit_not_equal] = AUDIT_NOT_EQUAL,
294 [Audit_bitmask] = AUDIT_BIT_MASK,
295 [Audit_bittest] = AUDIT_BIT_TEST,
296 [Audit_lt] = AUDIT_LESS_THAN,
297 [Audit_gt] = AUDIT_GREATER_THAN,
298 [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
299 [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
300 };
301
302 static u32 audit_to_op(u32 op)
303 {
304 u32 n;
305 for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
306 ;
307 return n;
308 }
309
310
311 /* Translate struct audit_rule to kernel's rule respresentation.
312 * Exists for backward compatibility with userspace. */
313 static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
314 {
315 struct audit_entry *entry;
316 int err = 0;
317 int i;
318
319 entry = audit_to_entry_common(rule);
320 if (IS_ERR(entry))
321 goto exit_nofree;
322
323 for (i = 0; i < rule->field_count; i++) {
324 struct audit_field *f = &entry->rule.fields[i];
325 u32 n;
326
327 n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
328
329 /* Support for legacy operators where
330 * AUDIT_NEGATE bit signifies != and otherwise assumes == */
331 if (n & AUDIT_NEGATE)
332 f->op = Audit_not_equal;
333 else if (!n)
334 f->op = Audit_equal;
335 else
336 f->op = audit_to_op(n);
337
338 entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1;
339
340 f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
341 f->val = rule->values[i];
342
343 err = -EINVAL;
344 if (f->op == Audit_bad)
345 goto exit_free;
346
347 switch(f->type) {
348 default:
349 goto exit_free;
350 case AUDIT_PID:
351 case AUDIT_UID:
352 case AUDIT_EUID:
353 case AUDIT_SUID:
354 case AUDIT_FSUID:
355 case AUDIT_GID:
356 case AUDIT_EGID:
357 case AUDIT_SGID:
358 case AUDIT_FSGID:
359 case AUDIT_LOGINUID:
360 case AUDIT_PERS:
361 case AUDIT_MSGTYPE:
362 case AUDIT_PPID:
363 case AUDIT_DEVMAJOR:
364 case AUDIT_DEVMINOR:
365 case AUDIT_EXIT:
366 case AUDIT_SUCCESS:
367 /* bit ops are only useful on syscall args */
368 if (f->op == Audit_bitmask || f->op == Audit_bittest)
369 goto exit_free;
370 break;
371 case AUDIT_ARG0:
372 case AUDIT_ARG1:
373 case AUDIT_ARG2:
374 case AUDIT_ARG3:
375 break;
376 /* arch is only allowed to be = or != */
377 case AUDIT_ARCH:
378 if (f->op != Audit_not_equal && f->op != Audit_equal)
379 goto exit_free;
380 entry->rule.arch_f = f;
381 break;
382 case AUDIT_PERM:
383 if (f->val & ~15)
384 goto exit_free;
385 break;
386 case AUDIT_FILETYPE:
387 if ((f->val & ~S_IFMT) > S_IFMT)
388 goto exit_free;
389 break;
390 case AUDIT_INODE:
391 err = audit_to_inode(&entry->rule, f);
392 if (err)
393 goto exit_free;
394 break;
395 }
396 }
397
398 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
399 entry->rule.inode_f = NULL;
400
401 exit_nofree:
402 return entry;
403
404 exit_free:
405 audit_free_rule(entry);
406 return ERR_PTR(err);
407 }
408
409 /* Translate struct audit_rule_data to kernel's rule respresentation. */
410 static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
411 size_t datasz)
412 {
413 int err = 0;
414 struct audit_entry *entry;
415 void *bufp;
416 size_t remain = datasz - sizeof(struct audit_rule_data);
417 int i;
418 char *str;
419
420 entry = audit_to_entry_common((struct audit_rule *)data);
421 if (IS_ERR(entry))
422 goto exit_nofree;
423
424 bufp = data->buf;
425 entry->rule.vers_ops = 2;
426 for (i = 0; i < data->field_count; i++) {
427 struct audit_field *f = &entry->rule.fields[i];
428
429 err = -EINVAL;
430
431 f->op = audit_to_op(data->fieldflags[i]);
432 if (f->op == Audit_bad)
433 goto exit_free;
434
435 f->type = data->fields[i];
436 f->val = data->values[i];
437 f->lsm_str = NULL;
438 f->lsm_rule = NULL;
439 switch(f->type) {
440 case AUDIT_PID:
441 case AUDIT_UID:
442 case AUDIT_EUID:
443 case AUDIT_SUID:
444 case AUDIT_FSUID:
445 case AUDIT_GID:
446 case AUDIT_EGID:
447 case AUDIT_SGID:
448 case AUDIT_FSGID:
449 case AUDIT_LOGINUID:
450 case AUDIT_PERS:
451 case AUDIT_MSGTYPE:
452 case AUDIT_PPID:
453 case AUDIT_DEVMAJOR:
454 case AUDIT_DEVMINOR:
455 case AUDIT_EXIT:
456 case AUDIT_SUCCESS:
457 case AUDIT_ARG0:
458 case AUDIT_ARG1:
459 case AUDIT_ARG2:
460 case AUDIT_ARG3:
461 break;
462 case AUDIT_ARCH:
463 entry->rule.arch_f = f;
464 break;
465 case AUDIT_SUBJ_USER:
466 case AUDIT_SUBJ_ROLE:
467 case AUDIT_SUBJ_TYPE:
468 case AUDIT_SUBJ_SEN:
469 case AUDIT_SUBJ_CLR:
470 case AUDIT_OBJ_USER:
471 case AUDIT_OBJ_ROLE:
472 case AUDIT_OBJ_TYPE:
473 case AUDIT_OBJ_LEV_LOW:
474 case AUDIT_OBJ_LEV_HIGH:
475 str = audit_unpack_string(&bufp, &remain, f->val);
476 if (IS_ERR(str))
477 goto exit_free;
478 entry->rule.buflen += f->val;
479
480 err = security_audit_rule_init(f->type, f->op, str,
481 (void **)&f->lsm_rule);
482 /* Keep currently invalid fields around in case they
483 * become valid after a policy reload. */
484 if (err == -EINVAL) {
485 printk(KERN_WARNING "audit rule for LSM "
486 "\'%s\' is invalid\n", str);
487 err = 0;
488 }
489 if (err) {
490 kfree(str);
491 goto exit_free;
492 } else
493 f->lsm_str = str;
494 break;
495 case AUDIT_WATCH:
496 str = audit_unpack_string(&bufp, &remain, f->val);
497 if (IS_ERR(str))
498 goto exit_free;
499 entry->rule.buflen += f->val;
500
501 err = audit_to_watch(&entry->rule, str, f->val, f->op);
502 if (err) {
503 kfree(str);
504 goto exit_free;
505 }
506 break;
507 case AUDIT_DIR:
508 str = audit_unpack_string(&bufp, &remain, f->val);
509 if (IS_ERR(str))
510 goto exit_free;
511 entry->rule.buflen += f->val;
512
513 err = audit_make_tree(&entry->rule, str, f->op);
514 kfree(str);
515 if (err)
516 goto exit_free;
517 break;
518 case AUDIT_INODE:
519 err = audit_to_inode(&entry->rule, f);
520 if (err)
521 goto exit_free;
522 break;
523 case AUDIT_FILTERKEY:
524 err = -EINVAL;
525 if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
526 goto exit_free;
527 str = audit_unpack_string(&bufp, &remain, f->val);
528 if (IS_ERR(str))
529 goto exit_free;
530 entry->rule.buflen += f->val;
531 entry->rule.filterkey = str;
532 break;
533 case AUDIT_PERM:
534 if (f->val & ~15)
535 goto exit_free;
536 break;
537 case AUDIT_FILETYPE:
538 if ((f->val & ~S_IFMT) > S_IFMT)
539 goto exit_free;
540 break;
541 default:
542 goto exit_free;
543 }
544 }
545
546 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
547 entry->rule.inode_f = NULL;
548
549 exit_nofree:
550 return entry;
551
552 exit_free:
553 audit_free_rule(entry);
554 return ERR_PTR(err);
555 }
556
557 /* Pack a filter field's string representation into data block. */
558 static inline size_t audit_pack_string(void **bufp, const char *str)
559 {
560 size_t len = strlen(str);
561
562 memcpy(*bufp, str, len);
563 *bufp += len;
564
565 return len;
566 }
567
568 /* Translate kernel rule respresentation to struct audit_rule.
569 * Exists for backward compatibility with userspace. */
570 static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
571 {
572 struct audit_rule *rule;
573 int i;
574
575 rule = kzalloc(sizeof(*rule), GFP_KERNEL);
576 if (unlikely(!rule))
577 return NULL;
578
579 rule->flags = krule->flags | krule->listnr;
580 rule->action = krule->action;
581 rule->field_count = krule->field_count;
582 for (i = 0; i < rule->field_count; i++) {
583 rule->values[i] = krule->fields[i].val;
584 rule->fields[i] = krule->fields[i].type;
585
586 if (krule->vers_ops == 1) {
587 if (krule->fields[i].op == Audit_not_equal)
588 rule->fields[i] |= AUDIT_NEGATE;
589 } else {
590 rule->fields[i] |= audit_ops[krule->fields[i].op];
591 }
592 }
593 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];
594
595 return rule;
596 }
597
598 /* Translate kernel rule respresentation to struct audit_rule_data. */
599 static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
600 {
601 struct audit_rule_data *data;
602 void *bufp;
603 int i;
604
605 data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
606 if (unlikely(!data))
607 return NULL;
608 memset(data, 0, sizeof(*data));
609
610 data->flags = krule->flags | krule->listnr;
611 data->action = krule->action;
612 data->field_count = krule->field_count;
613 bufp = data->buf;
614 for (i = 0; i < data->field_count; i++) {
615 struct audit_field *f = &krule->fields[i];
616
617 data->fields[i] = f->type;
618 data->fieldflags[i] = audit_ops[f->op];
619 switch(f->type) {
620 case AUDIT_SUBJ_USER:
621 case AUDIT_SUBJ_ROLE:
622 case AUDIT_SUBJ_TYPE:
623 case AUDIT_SUBJ_SEN:
624 case AUDIT_SUBJ_CLR:
625 case AUDIT_OBJ_USER:
626 case AUDIT_OBJ_ROLE:
627 case AUDIT_OBJ_TYPE:
628 case AUDIT_OBJ_LEV_LOW:
629 case AUDIT_OBJ_LEV_HIGH:
630 data->buflen += data->values[i] =
631 audit_pack_string(&bufp, f->lsm_str);
632 break;
633 case AUDIT_WATCH:
634 data->buflen += data->values[i] =
635 audit_pack_string(&bufp,
636 audit_watch_path(krule->watch));
637 break;
638 case AUDIT_DIR:
639 data->buflen += data->values[i] =
640 audit_pack_string(&bufp,
641 audit_tree_path(krule->tree));
642 break;
643 case AUDIT_FILTERKEY:
644 data->buflen += data->values[i] =
645 audit_pack_string(&bufp, krule->filterkey);
646 break;
647 default:
648 data->values[i] = f->val;
649 }
650 }
651 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
652
653 return data;
654 }
655
656 /* Compare two rules in kernel format. Considered success if rules
657 * don't match. */
658 static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
659 {
660 int i;
661
662 if (a->flags != b->flags ||
663 a->listnr != b->listnr ||
664 a->action != b->action ||
665 a->field_count != b->field_count)
666 return 1;
667
668 for (i = 0; i < a->field_count; i++) {
669 if (a->fields[i].type != b->fields[i].type ||
670 a->fields[i].op != b->fields[i].op)
671 return 1;
672
673 switch(a->fields[i].type) {
674 case AUDIT_SUBJ_USER:
675 case AUDIT_SUBJ_ROLE:
676 case AUDIT_SUBJ_TYPE:
677 case AUDIT_SUBJ_SEN:
678 case AUDIT_SUBJ_CLR:
679 case AUDIT_OBJ_USER:
680 case AUDIT_OBJ_ROLE:
681 case AUDIT_OBJ_TYPE:
682 case AUDIT_OBJ_LEV_LOW:
683 case AUDIT_OBJ_LEV_HIGH:
684 if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
685 return 1;
686 break;
687 case AUDIT_WATCH:
688 if (strcmp(audit_watch_path(a->watch),
689 audit_watch_path(b->watch)))
690 return 1;
691 break;
692 case AUDIT_DIR:
693 if (strcmp(audit_tree_path(a->tree),
694 audit_tree_path(b->tree)))
695 return 1;
696 break;
697 case AUDIT_FILTERKEY:
698 /* both filterkeys exist based on above type compare */
699 if (strcmp(a->filterkey, b->filterkey))
700 return 1;
701 break;
702 default:
703 if (a->fields[i].val != b->fields[i].val)
704 return 1;
705 }
706 }
707
708 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
709 if (a->mask[i] != b->mask[i])
710 return 1;
711
712 return 0;
713 }
714
715 /* Duplicate LSM field information. The lsm_rule is opaque, so must be
716 * re-initialized. */
717 static inline int audit_dupe_lsm_field(struct audit_field *df,
718 struct audit_field *sf)
719 {
720 int ret = 0;
721 char *lsm_str;
722
723 /* our own copy of lsm_str */
724 lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
725 if (unlikely(!lsm_str))
726 return -ENOMEM;
727 df->lsm_str = lsm_str;
728
729 /* our own (refreshed) copy of lsm_rule */
730 ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
731 (void **)&df->lsm_rule);
732 /* Keep currently invalid fields around in case they
733 * become valid after a policy reload. */
734 if (ret == -EINVAL) {
735 printk(KERN_WARNING "audit rule for LSM \'%s\' is "
736 "invalid\n", df->lsm_str);
737 ret = 0;
738 }
739
740 return ret;
741 }
742
743 /* Duplicate an audit rule. This will be a deep copy with the exception
744 * of the watch - that pointer is carried over. The LSM specific fields
745 * will be updated in the copy. The point is to be able to replace the old
746 * rule with the new rule in the filterlist, then free the old rule.
747 * The rlist element is undefined; list manipulations are handled apart from
748 * the initial copy. */
749 struct audit_entry *audit_dupe_rule(struct audit_krule *old)
750 {
751 u32 fcount = old->field_count;
752 struct audit_entry *entry;
753 struct audit_krule *new;
754 char *fk;
755 int i, err = 0;
756
757 entry = audit_init_entry(fcount);
758 if (unlikely(!entry))
759 return ERR_PTR(-ENOMEM);
760
761 new = &entry->rule;
762 new->vers_ops = old->vers_ops;
763 new->flags = old->flags;
764 new->listnr = old->listnr;
765 new->action = old->action;
766 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
767 new->mask[i] = old->mask[i];
768 new->prio = old->prio;
769 new->buflen = old->buflen;
770 new->inode_f = old->inode_f;
771 new->field_count = old->field_count;
772
773 /*
774 * note that we are OK with not refcounting here; audit_match_tree()
775 * never dereferences tree and we can't get false positives there
776 * since we'd have to have rule gone from the list *and* removed
777 * before the chunks found by lookup had been allocated, i.e. before
778 * the beginning of list scan.
779 */
780 new->tree = old->tree;
781 memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
782
783 /* deep copy this information, updating the lsm_rule fields, because
784 * the originals will all be freed when the old rule is freed. */
785 for (i = 0; i < fcount; i++) {
786 switch (new->fields[i].type) {
787 case AUDIT_SUBJ_USER:
788 case AUDIT_SUBJ_ROLE:
789 case AUDIT_SUBJ_TYPE:
790 case AUDIT_SUBJ_SEN:
791 case AUDIT_SUBJ_CLR:
792 case AUDIT_OBJ_USER:
793 case AUDIT_OBJ_ROLE:
794 case AUDIT_OBJ_TYPE:
795 case AUDIT_OBJ_LEV_LOW:
796 case AUDIT_OBJ_LEV_HIGH:
797 err = audit_dupe_lsm_field(&new->fields[i],
798 &old->fields[i]);
799 break;
800 case AUDIT_FILTERKEY:
801 fk = kstrdup(old->filterkey, GFP_KERNEL);
802 if (unlikely(!fk))
803 err = -ENOMEM;
804 else
805 new->filterkey = fk;
806 }
807 if (err) {
808 audit_free_rule(entry);
809 return ERR_PTR(err);
810 }
811 }
812
813 if (old->watch) {
814 audit_get_watch(old->watch);
815 new->watch = old->watch;
816 }
817
818 return entry;
819 }
820
821 /* Find an existing audit rule.
822 * Caller must hold audit_filter_mutex to prevent stale rule data. */
823 static struct audit_entry *audit_find_rule(struct audit_entry *entry,
824 struct list_head **p)
825 {
826 struct audit_entry *e, *found = NULL;
827 struct list_head *list;
828 int h;
829
830 if (entry->rule.inode_f) {
831 h = audit_hash_ino(entry->rule.inode_f->val);
832 *p = list = &audit_inode_hash[h];
833 } else if (entry->rule.watch) {
834 /* we don't know the inode number, so must walk entire hash */
835 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
836 list = &audit_inode_hash[h];
837 list_for_each_entry(e, list, list)
838 if (!audit_compare_rule(&entry->rule, &e->rule)) {
839 found = e;
840 goto out;
841 }
842 }
843 goto out;
844 } else {
845 *p = list = &audit_filter_list[entry->rule.listnr];
846 }
847
848 list_for_each_entry(e, list, list)
849 if (!audit_compare_rule(&entry->rule, &e->rule)) {
850 found = e;
851 goto out;
852 }
853
854 out:
855 return found;
856 }
857
858 static u64 prio_low = ~0ULL/2;
859 static u64 prio_high = ~0ULL/2 - 1;
860
861 /* Add rule to given filterlist if not a duplicate. */
862 static inline int audit_add_rule(struct audit_entry *entry)
863 {
864 struct audit_entry *e;
865 struct audit_watch *watch = entry->rule.watch;
866 struct audit_tree *tree = entry->rule.tree;
867 struct list_head *list;
868 int err;
869 #ifdef CONFIG_AUDITSYSCALL
870 int dont_count = 0;
871
872 /* If either of these, don't count towards total */
873 if (entry->rule.listnr == AUDIT_FILTER_USER ||
874 entry->rule.listnr == AUDIT_FILTER_TYPE)
875 dont_count = 1;
876 #endif
877
878 mutex_lock(&audit_filter_mutex);
879 e = audit_find_rule(entry, &list);
880 if (e) {
881 mutex_unlock(&audit_filter_mutex);
882 err = -EEXIST;
883 /* normally audit_add_tree_rule() will free it on failure */
884 if (tree)
885 audit_put_tree(tree);
886 goto error;
887 }
888
889 if (watch) {
890 /* audit_filter_mutex is dropped and re-taken during this call */
891 err = audit_add_watch(&entry->rule, &list);
892 if (err) {
893 mutex_unlock(&audit_filter_mutex);
894 goto error;
895 }
896 }
897 if (tree) {
898 err = audit_add_tree_rule(&entry->rule);
899 if (err) {
900 mutex_unlock(&audit_filter_mutex);
901 goto error;
902 }
903 }
904
905 entry->rule.prio = ~0ULL;
906 if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
907 if (entry->rule.flags & AUDIT_FILTER_PREPEND)
908 entry->rule.prio = ++prio_high;
909 else
910 entry->rule.prio = --prio_low;
911 }
912
913 if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
914 list_add(&entry->rule.list,
915 &audit_rules_list[entry->rule.listnr]);
916 list_add_rcu(&entry->list, list);
917 entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
918 } else {
919 list_add_tail(&entry->rule.list,
920 &audit_rules_list[entry->rule.listnr]);
921 list_add_tail_rcu(&entry->list, list);
922 }
923 #ifdef CONFIG_AUDITSYSCALL
924 if (!dont_count)
925 audit_n_rules++;
926
927 if (!audit_match_signal(entry))
928 audit_signals++;
929 #endif
930 mutex_unlock(&audit_filter_mutex);
931
932 return 0;
933
934 error:
935 if (watch)
936 audit_put_watch(watch); /* tmp watch, matches initial get */
937 return err;
938 }
939
940 /* Remove an existing rule from filterlist. */
941 static inline int audit_del_rule(struct audit_entry *entry)
942 {
943 struct audit_entry *e;
944 struct audit_watch *watch = entry->rule.watch;
945 struct audit_tree *tree = entry->rule.tree;
946 struct list_head *list;
947 int ret = 0;
948 #ifdef CONFIG_AUDITSYSCALL
949 int dont_count = 0;
950
951 /* If either of these, don't count towards total */
952 if (entry->rule.listnr == AUDIT_FILTER_USER ||
953 entry->rule.listnr == AUDIT_FILTER_TYPE)
954 dont_count = 1;
955 #endif
956
957 mutex_lock(&audit_filter_mutex);
958 e = audit_find_rule(entry, &list);
959 if (!e) {
960 mutex_unlock(&audit_filter_mutex);
961 ret = -ENOENT;
962 goto out;
963 }
964
965 if (e->rule.watch)
966 audit_remove_watch_rule(&e->rule);
967
968 if (e->rule.tree)
969 audit_remove_tree_rule(&e->rule);
970
971 list_del_rcu(&e->list);
972 list_del(&e->rule.list);
973 call_rcu(&e->rcu, audit_free_rule_rcu);
974
975 #ifdef CONFIG_AUDITSYSCALL
976 if (!dont_count)
977 audit_n_rules--;
978
979 if (!audit_match_signal(entry))
980 audit_signals--;
981 #endif
982 mutex_unlock(&audit_filter_mutex);
983
984 out:
985 if (watch)
986 audit_put_watch(watch); /* match initial get */
987 if (tree)
988 audit_put_tree(tree); /* that's the temporary one */
989
990 return ret;
991 }
992
993 /* List rules using struct audit_rule. Exists for backward
994 * compatibility with userspace. */
995 static void audit_list(int pid, int seq, struct sk_buff_head *q)
996 {
997 struct sk_buff *skb;
998 struct audit_krule *r;
999 int i;
1000
1001 /* This is a blocking read, so use audit_filter_mutex instead of rcu
1002 * iterator to sync with list writers. */
1003 for (i=0; i<AUDIT_NR_FILTERS; i++) {
1004 list_for_each_entry(r, &audit_rules_list[i], list) {
1005 struct audit_rule *rule;
1006
1007 rule = audit_krule_to_rule(r);
1008 if (unlikely(!rule))
1009 break;
1010 skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
1011 rule, sizeof(*rule));
1012 if (skb)
1013 skb_queue_tail(q, skb);
1014 kfree(rule);
1015 }
1016 }
1017 skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
1018 if (skb)
1019 skb_queue_tail(q, skb);
1020 }
1021
1022 /* List rules using struct audit_rule_data. */
1023 static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
1024 {
1025 struct sk_buff *skb;
1026 struct audit_krule *r;
1027 int i;
1028
1029 /* This is a blocking read, so use audit_filter_mutex instead of rcu
1030 * iterator to sync with list writers. */
1031 for (i=0; i<AUDIT_NR_FILTERS; i++) {
1032 list_for_each_entry(r, &audit_rules_list[i], list) {
1033 struct audit_rule_data *data;
1034
1035 data = audit_krule_to_data(r);
1036 if (unlikely(!data))
1037 break;
1038 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
1039 data, sizeof(*data) + data->buflen);
1040 if (skb)
1041 skb_queue_tail(q, skb);
1042 kfree(data);
1043 }
1044 }
1045 skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1046 if (skb)
1047 skb_queue_tail(q, skb);
1048 }
1049
1050 /* Log rule additions and removals */
1051 static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid,
1052 char *action, struct audit_krule *rule,
1053 int res)
1054 {
1055 struct audit_buffer *ab;
1056
1057 if (!audit_enabled)
1058 return;
1059
1060 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1061 if (!ab)
1062 return;
1063 audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid);
1064 if (sid) {
1065 char *ctx = NULL;
1066 u32 len;
1067 if (security_secid_to_secctx(sid, &ctx, &len))
1068 audit_log_format(ab, " ssid=%u", sid);
1069 else {
1070 audit_log_format(ab, " subj=%s", ctx);
1071 security_release_secctx(ctx, len);
1072 }
1073 }
1074 audit_log_format(ab, " op=");
1075 audit_log_string(ab, action);
1076 audit_log_key(ab, rule->filterkey);
1077 audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1078 audit_log_end(ab);
1079 }
1080
1081 /**
1082 * audit_receive_filter - apply all rules to the specified message type
1083 * @type: audit message type
1084 * @pid: target pid for netlink audit messages
1085 * @uid: target uid for netlink audit messages
1086 * @seq: netlink audit message sequence (serial) number
1087 * @data: payload data
1088 * @datasz: size of payload data
1089 * @loginuid: loginuid of sender
1090 * @sessionid: sessionid for netlink audit message
1091 * @sid: SE Linux Security ID of sender
1092 */
1093 int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
1094 size_t datasz, uid_t loginuid, u32 sessionid, u32 sid)
1095 {
1096 struct task_struct *tsk;
1097 struct audit_netlink_list *dest;
1098 int err = 0;
1099 struct audit_entry *entry;
1100
1101 switch (type) {
1102 case AUDIT_LIST:
1103 case AUDIT_LIST_RULES:
1104 /* We can't just spew out the rules here because we might fill
1105 * the available socket buffer space and deadlock waiting for
1106 * auditctl to read from it... which isn't ever going to
1107 * happen if we're actually running in the context of auditctl
1108 * trying to _send_ the stuff */
1109
1110 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1111 if (!dest)
1112 return -ENOMEM;
1113 dest->pid = pid;
1114 skb_queue_head_init(&dest->q);
1115
1116 mutex_lock(&audit_filter_mutex);
1117 if (type == AUDIT_LIST)
1118 audit_list(pid, seq, &dest->q);
1119 else
1120 audit_list_rules(pid, seq, &dest->q);
1121 mutex_unlock(&audit_filter_mutex);
1122
1123 tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1124 if (IS_ERR(tsk)) {
1125 skb_queue_purge(&dest->q);
1126 kfree(dest);
1127 err = PTR_ERR(tsk);
1128 }
1129 break;
1130 case AUDIT_ADD:
1131 case AUDIT_ADD_RULE:
1132 if (type == AUDIT_ADD)
1133 entry = audit_rule_to_entry(data);
1134 else
1135 entry = audit_data_to_entry(data, datasz);
1136 if (IS_ERR(entry))
1137 return PTR_ERR(entry);
1138
1139 err = audit_add_rule(entry);
1140 audit_log_rule_change(loginuid, sessionid, sid, "add rule",
1141 &entry->rule, !err);
1142
1143 if (err)
1144 audit_free_rule(entry);
1145 break;
1146 case AUDIT_DEL:
1147 case AUDIT_DEL_RULE:
1148 if (type == AUDIT_DEL)
1149 entry = audit_rule_to_entry(data);
1150 else
1151 entry = audit_data_to_entry(data, datasz);
1152 if (IS_ERR(entry))
1153 return PTR_ERR(entry);
1154
1155 err = audit_del_rule(entry);
1156 audit_log_rule_change(loginuid, sessionid, sid, "remove rule",
1157 &entry->rule, !err);
1158
1159 audit_free_rule(entry);
1160 break;
1161 default:
1162 return -EINVAL;
1163 }
1164
1165 return err;
1166 }
1167
1168 int audit_comparator(u32 left, u32 op, u32 right)
1169 {
1170 switch (op) {
1171 case Audit_equal:
1172 return (left == right);
1173 case Audit_not_equal:
1174 return (left != right);
1175 case Audit_lt:
1176 return (left < right);
1177 case Audit_le:
1178 return (left <= right);
1179 case Audit_gt:
1180 return (left > right);
1181 case Audit_ge:
1182 return (left >= right);
1183 case Audit_bitmask:
1184 return (left & right);
1185 case Audit_bittest:
1186 return ((left & right) == right);
1187 default:
1188 BUG();
1189 return 0;
1190 }
1191 }
1192
1193 /* Compare given dentry name with last component in given path,
1194 * return of 0 indicates a match. */
1195 int audit_compare_dname_path(const char *dname, const char *path,
1196 int *dirlen)
1197 {
1198 int dlen, plen;
1199 const char *p;
1200
1201 if (!dname || !path)
1202 return 1;
1203
1204 dlen = strlen(dname);
1205 plen = strlen(path);
1206 if (plen < dlen)
1207 return 1;
1208
1209 /* disregard trailing slashes */
1210 p = path + plen - 1;
1211 while ((*p == '/') && (p > path))
1212 p--;
1213
1214 /* find last path component */
1215 p = p - dlen + 1;
1216 if (p < path)
1217 return 1;
1218 else if (p > path) {
1219 if (*--p != '/')
1220 return 1;
1221 else
1222 p++;
1223 }
1224
1225 /* return length of path's directory component */
1226 if (dirlen)
1227 *dirlen = p - path;
1228 return strncmp(p, dname, dlen);
1229 }
1230
1231 static int audit_filter_user_rules(struct netlink_skb_parms *cb,
1232 struct audit_krule *rule,
1233 enum audit_state *state)
1234 {
1235 int i;
1236
1237 for (i = 0; i < rule->field_count; i++) {
1238 struct audit_field *f = &rule->fields[i];
1239 int result = 0;
1240
1241 switch (f->type) {
1242 case AUDIT_PID:
1243 result = audit_comparator(cb->creds.pid, f->op, f->val);
1244 break;
1245 case AUDIT_UID:
1246 result = audit_comparator(cb->creds.uid, f->op, f->val);
1247 break;
1248 case AUDIT_GID:
1249 result = audit_comparator(cb->creds.gid, f->op, f->val);
1250 break;
1251 case AUDIT_LOGINUID:
1252 result = audit_comparator(cb->loginuid, f->op, f->val);
1253 break;
1254 }
1255
1256 if (!result)
1257 return 0;
1258 }
1259 switch (rule->action) {
1260 case AUDIT_NEVER: *state = AUDIT_DISABLED; break;
1261 case AUDIT_ALWAYS: *state = AUDIT_RECORD_CONTEXT; break;
1262 }
1263 return 1;
1264 }
1265
1266 int audit_filter_user(struct netlink_skb_parms *cb)
1267 {
1268 enum audit_state state = AUDIT_DISABLED;
1269 struct audit_entry *e;
1270 int ret = 1;
1271
1272 rcu_read_lock();
1273 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
1274 if (audit_filter_user_rules(cb, &e->rule, &state)) {
1275 if (state == AUDIT_DISABLED)
1276 ret = 0;
1277 break;
1278 }
1279 }
1280 rcu_read_unlock();
1281
1282 return ret; /* Audit by default */
1283 }
1284
1285 int audit_filter_type(int type)
1286 {
1287 struct audit_entry *e;
1288 int result = 0;
1289
1290 rcu_read_lock();
1291 if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
1292 goto unlock_and_return;
1293
1294 list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
1295 list) {
1296 int i;
1297 for (i = 0; i < e->rule.field_count; i++) {
1298 struct audit_field *f = &e->rule.fields[i];
1299 if (f->type == AUDIT_MSGTYPE) {
1300 result = audit_comparator(type, f->op, f->val);
1301 if (!result)
1302 break;
1303 }
1304 }
1305 if (result)
1306 goto unlock_and_return;
1307 }
1308 unlock_and_return:
1309 rcu_read_unlock();
1310 return result;
1311 }
1312
1313 static int update_lsm_rule(struct audit_krule *r)
1314 {
1315 struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1316 struct audit_entry *nentry;
1317 int err = 0;
1318
1319 if (!security_audit_rule_known(r))
1320 return 0;
1321
1322 nentry = audit_dupe_rule(r);
1323 if (IS_ERR(nentry)) {
1324 /* save the first error encountered for the
1325 * return value */
1326 err = PTR_ERR(nentry);
1327 audit_panic("error updating LSM filters");
1328 if (r->watch)
1329 list_del(&r->rlist);
1330 list_del_rcu(&entry->list);
1331 list_del(&r->list);
1332 } else {
1333 if (r->watch || r->tree)
1334 list_replace_init(&r->rlist, &nentry->rule.rlist);
1335 list_replace_rcu(&entry->list, &nentry->list);
1336 list_replace(&r->list, &nentry->rule.list);
1337 }
1338 call_rcu(&entry->rcu, audit_free_rule_rcu);
1339
1340 return err;
1341 }
1342
1343 /* This function will re-initialize the lsm_rule field of all applicable rules.
1344 * It will traverse the filter lists serarching for rules that contain LSM
1345 * specific filter fields. When such a rule is found, it is copied, the
1346 * LSM field is re-initialized, and the old rule is replaced with the
1347 * updated rule. */
1348 int audit_update_lsm_rules(void)
1349 {
1350 struct audit_krule *r, *n;
1351 int i, err = 0;
1352
1353 /* audit_filter_mutex synchronizes the writers */
1354 mutex_lock(&audit_filter_mutex);
1355
1356 for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1357 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1358 int res = update_lsm_rule(r);
1359 if (!err)
1360 err = res;
1361 }
1362 }
1363 mutex_unlock(&audit_filter_mutex);
1364
1365 return err;
1366 }
mm of the moment repository