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blkcg: use double locking instead of RCU for blkg synchronization
[linux-2.6.git] / kernel / auditfilter.c
bloba6c3f1abd206c9d9736cbe5834483e36fd1d62ff
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
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
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. */
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. */
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. */
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
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
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
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
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. */
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
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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. */
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 */
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 */
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
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. */
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
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
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
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
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. */
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 }
Linus' kernel tree