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path: root/kernel/auditfilter.c (plain)
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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
23
24#include <linux/kernel.h>
25#include <linux/audit.h>
26#include <linux/kthread.h>
27#include <linux/mutex.h>
28#include <linux/fs.h>
29#include <linux/namei.h>
30#include <linux/netlink.h>
31#include <linux/sched.h>
32#include <linux/slab.h>
33#include <linux/security.h>
34#include <net/net_namespace.h>
35#include <net/sock.h>
36#include "audit.h"
37
38/*
39 * Locking model:
40 *
41 * audit_filter_mutex:
42 * Synchronizes writes and blocking reads of audit's filterlist
43 * data. Rcu is used to traverse the filterlist and access
44 * contents of structs audit_entry, audit_watch and opaque
45 * LSM rules during filtering. If modified, these structures
46 * must be copied and replace their counterparts in the filterlist.
47 * An audit_parent struct is not accessed during filtering, so may
48 * be written directly provided audit_filter_mutex is held.
49 */
50
51/* Audit filter lists, defined in <linux/audit.h> */
52struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
53 LIST_HEAD_INIT(audit_filter_list[0]),
54 LIST_HEAD_INIT(audit_filter_list[1]),
55 LIST_HEAD_INIT(audit_filter_list[2]),
56 LIST_HEAD_INIT(audit_filter_list[3]),
57 LIST_HEAD_INIT(audit_filter_list[4]),
58 LIST_HEAD_INIT(audit_filter_list[5]),
59#if AUDIT_NR_FILTERS != 6
60#error Fix audit_filter_list initialiser
61#endif
62};
63static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
64 LIST_HEAD_INIT(audit_rules_list[0]),
65 LIST_HEAD_INIT(audit_rules_list[1]),
66 LIST_HEAD_INIT(audit_rules_list[2]),
67 LIST_HEAD_INIT(audit_rules_list[3]),
68 LIST_HEAD_INIT(audit_rules_list[4]),
69 LIST_HEAD_INIT(audit_rules_list[5]),
70};
71
72DEFINE_MUTEX(audit_filter_mutex);
73
74static void audit_free_lsm_field(struct audit_field *f)
75{
76 switch (f->type) {
77 case AUDIT_SUBJ_USER:
78 case AUDIT_SUBJ_ROLE:
79 case AUDIT_SUBJ_TYPE:
80 case AUDIT_SUBJ_SEN:
81 case AUDIT_SUBJ_CLR:
82 case AUDIT_OBJ_USER:
83 case AUDIT_OBJ_ROLE:
84 case AUDIT_OBJ_TYPE:
85 case AUDIT_OBJ_LEV_LOW:
86 case AUDIT_OBJ_LEV_HIGH:
87 kfree(f->lsm_str);
88 security_audit_rule_free(f->lsm_rule);
89 }
90}
91
92static inline void audit_free_rule(struct audit_entry *e)
93{
94 int i;
95 struct audit_krule *erule = &e->rule;
96
97 /* some rules don't have associated watches */
98 if (erule->watch)
99 audit_put_watch(erule->watch);
100 if (erule->fields)
101 for (i = 0; i < erule->field_count; i++)
102 audit_free_lsm_field(&erule->fields[i]);
103 kfree(erule->fields);
104 kfree(erule->filterkey);
105 kfree(e);
106}
107
108void audit_free_rule_rcu(struct rcu_head *head)
109{
110 struct audit_entry *e = container_of(head, struct audit_entry, rcu);
111 audit_free_rule(e);
112}
113
114/* Initialize an audit filterlist entry. */
115static inline struct audit_entry *audit_init_entry(u32 field_count)
116{
117 struct audit_entry *entry;
118 struct audit_field *fields;
119
120 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
121 if (unlikely(!entry))
122 return NULL;
123
124 fields = kcalloc(field_count, sizeof(*fields), GFP_KERNEL);
125 if (unlikely(!fields)) {
126 kfree(entry);
127 return NULL;
128 }
129 entry->rule.fields = fields;
130
131 return entry;
132}
133
134/* Unpack a filter field's string representation from user-space
135 * buffer. */
136char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
137{
138 char *str;
139
140 if (!*bufp || (len == 0) || (len > *remain))
141 return ERR_PTR(-EINVAL);
142
143 /* Of the currently implemented string fields, PATH_MAX
144 * defines the longest valid length.
145 */
146 if (len > PATH_MAX)
147 return ERR_PTR(-ENAMETOOLONG);
148
149 str = kmalloc(len + 1, GFP_KERNEL);
150 if (unlikely(!str))
151 return ERR_PTR(-ENOMEM);
152
153 memcpy(str, *bufp, len);
154 str[len] = 0;
155 *bufp += len;
156 *remain -= len;
157
158 return str;
159}
160
161/* Translate an inode field to kernel representation. */
162static inline int audit_to_inode(struct audit_krule *krule,
163 struct audit_field *f)
164{
165 if (krule->listnr != AUDIT_FILTER_EXIT ||
166 krule->inode_f || krule->watch || krule->tree ||
167 (f->op != Audit_equal && f->op != Audit_not_equal))
168 return -EINVAL;
169
170 krule->inode_f = f;
171 return 0;
172}
173
174static __u32 *classes[AUDIT_SYSCALL_CLASSES];
175
176int __init audit_register_class(int class, unsigned *list)
177{
178 __u32 *p = kcalloc(AUDIT_BITMASK_SIZE, sizeof(__u32), GFP_KERNEL);
179 if (!p)
180 return -ENOMEM;
181 while (*list != ~0U) {
182 unsigned n = *list++;
183 if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
184 kfree(p);
185 return -EINVAL;
186 }
187 p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
188 }
189 if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
190 kfree(p);
191 return -EINVAL;
192 }
193 classes[class] = p;
194 return 0;
195}
196
197int audit_match_class(int class, unsigned syscall)
198{
199 if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
200 return 0;
201 if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
202 return 0;
203 return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
204}
205
206#ifdef CONFIG_AUDITSYSCALL
207static inline int audit_match_class_bits(int class, u32 *mask)
208{
209 int i;
210
211 if (classes[class]) {
212 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
213 if (mask[i] & classes[class][i])
214 return 0;
215 }
216 return 1;
217}
218
219static int audit_match_signal(struct audit_entry *entry)
220{
221 struct audit_field *arch = entry->rule.arch_f;
222
223 if (!arch) {
224 /* When arch is unspecified, we must check both masks on biarch
225 * as syscall number alone is ambiguous. */
226 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
227 entry->rule.mask) &&
228 audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
229 entry->rule.mask));
230 }
231
232 switch(audit_classify_arch(arch->val)) {
233 case 0: /* native */
234 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
235 entry->rule.mask));
236 case 1: /* 32bit on biarch */
237 return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
238 entry->rule.mask));
239 default:
240 return 1;
241 }
242}
243#endif
244
245/* Common user-space to kernel rule translation. */
246static inline struct audit_entry *audit_to_entry_common(struct audit_rule_data *rule)
247{
248 unsigned listnr;
249 struct audit_entry *entry;
250 int i, err;
251
252 err = -EINVAL;
253 listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
254 switch(listnr) {
255 default:
256 goto exit_err;
257#ifdef CONFIG_AUDITSYSCALL
258 case AUDIT_FILTER_ENTRY:
259 if (rule->action == AUDIT_ALWAYS)
260 goto exit_err;
261 case AUDIT_FILTER_EXIT:
262 case AUDIT_FILTER_TASK:
263#endif
264 case AUDIT_FILTER_USER:
265 case AUDIT_FILTER_TYPE:
266 ;
267 }
268 if (unlikely(rule->action == AUDIT_POSSIBLE)) {
269 pr_err("AUDIT_POSSIBLE is deprecated\n");
270 goto exit_err;
271 }
272 if (rule->action != AUDIT_NEVER && rule->action != AUDIT_ALWAYS)
273 goto exit_err;
274 if (rule->field_count > AUDIT_MAX_FIELDS)
275 goto exit_err;
276
277 err = -ENOMEM;
278 entry = audit_init_entry(rule->field_count);
279 if (!entry)
280 goto exit_err;
281
282 entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
283 entry->rule.listnr = listnr;
284 entry->rule.action = rule->action;
285 entry->rule.field_count = rule->field_count;
286
287 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
288 entry->rule.mask[i] = rule->mask[i];
289
290 for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
291 int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
292 __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
293 __u32 *class;
294
295 if (!(*p & AUDIT_BIT(bit)))
296 continue;
297 *p &= ~AUDIT_BIT(bit);
298 class = classes[i];
299 if (class) {
300 int j;
301 for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
302 entry->rule.mask[j] |= class[j];
303 }
304 }
305
306 return entry;
307
308exit_err:
309 return ERR_PTR(err);
310}
311
312static u32 audit_ops[] =
313{
314 [Audit_equal] = AUDIT_EQUAL,
315 [Audit_not_equal] = AUDIT_NOT_EQUAL,
316 [Audit_bitmask] = AUDIT_BIT_MASK,
317 [Audit_bittest] = AUDIT_BIT_TEST,
318 [Audit_lt] = AUDIT_LESS_THAN,
319 [Audit_gt] = AUDIT_GREATER_THAN,
320 [Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
321 [Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
322};
323
324static u32 audit_to_op(u32 op)
325{
326 u32 n;
327 for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
328 ;
329 return n;
330}
331
332/* check if an audit field is valid */
333static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
334{
335 switch(f->type) {
336 case AUDIT_MSGTYPE:
337 if (entry->rule.listnr != AUDIT_FILTER_TYPE &&
338 entry->rule.listnr != AUDIT_FILTER_USER)
339 return -EINVAL;
340 break;
341 };
342
343 switch(f->type) {
344 default:
345 return -EINVAL;
346 case AUDIT_UID:
347 case AUDIT_EUID:
348 case AUDIT_SUID:
349 case AUDIT_FSUID:
350 case AUDIT_LOGINUID:
351 case AUDIT_OBJ_UID:
352 case AUDIT_GID:
353 case AUDIT_EGID:
354 case AUDIT_SGID:
355 case AUDIT_FSGID:
356 case AUDIT_OBJ_GID:
357 case AUDIT_PID:
358 case AUDIT_PERS:
359 case AUDIT_MSGTYPE:
360 case AUDIT_PPID:
361 case AUDIT_DEVMAJOR:
362 case AUDIT_DEVMINOR:
363 case AUDIT_EXIT:
364 case AUDIT_SUCCESS:
365 case AUDIT_INODE:
366 /* bit ops are only useful on syscall args */
367 if (f->op == Audit_bitmask || f->op == Audit_bittest)
368 return -EINVAL;
369 break;
370 case AUDIT_ARG0:
371 case AUDIT_ARG1:
372 case AUDIT_ARG2:
373 case AUDIT_ARG3:
374 case AUDIT_SUBJ_USER:
375 case AUDIT_SUBJ_ROLE:
376 case AUDIT_SUBJ_TYPE:
377 case AUDIT_SUBJ_SEN:
378 case AUDIT_SUBJ_CLR:
379 case AUDIT_OBJ_USER:
380 case AUDIT_OBJ_ROLE:
381 case AUDIT_OBJ_TYPE:
382 case AUDIT_OBJ_LEV_LOW:
383 case AUDIT_OBJ_LEV_HIGH:
384 case AUDIT_WATCH:
385 case AUDIT_DIR:
386 case AUDIT_FILTERKEY:
387 break;
388 case AUDIT_LOGINUID_SET:
389 if ((f->val != 0) && (f->val != 1))
390 return -EINVAL;
391 /* FALL THROUGH */
392 case AUDIT_ARCH:
393 if (f->op != Audit_not_equal && f->op != Audit_equal)
394 return -EINVAL;
395 break;
396 case AUDIT_PERM:
397 if (f->val & ~15)
398 return -EINVAL;
399 break;
400 case AUDIT_FILETYPE:
401 if (f->val & ~S_IFMT)
402 return -EINVAL;
403 break;
404 case AUDIT_FIELD_COMPARE:
405 if (f->val > AUDIT_MAX_FIELD_COMPARE)
406 return -EINVAL;
407 break;
408 case AUDIT_EXE:
409 if (f->op != Audit_not_equal && f->op != Audit_equal)
410 return -EINVAL;
411 if (entry->rule.listnr != AUDIT_FILTER_EXIT)
412 return -EINVAL;
413 break;
414 };
415 return 0;
416}
417
418/* Translate struct audit_rule_data to kernel's rule representation. */
419static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
420 size_t datasz)
421{
422 int err = 0;
423 struct audit_entry *entry;
424 void *bufp;
425 size_t remain = datasz - sizeof(struct audit_rule_data);
426 int i;
427 char *str;
428 struct audit_fsnotify_mark *audit_mark;
429
430 entry = audit_to_entry_common(data);
431 if (IS_ERR(entry))
432 goto exit_nofree;
433
434 bufp = data->buf;
435 for (i = 0; i < data->field_count; i++) {
436 struct audit_field *f = &entry->rule.fields[i];
437
438 err = -EINVAL;
439
440 f->op = audit_to_op(data->fieldflags[i]);
441 if (f->op == Audit_bad)
442 goto exit_free;
443
444 f->type = data->fields[i];
445 f->val = data->values[i];
446
447 /* Support legacy tests for a valid loginuid */
448 if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) {
449 f->type = AUDIT_LOGINUID_SET;
450 f->val = 0;
451 entry->rule.pflags |= AUDIT_LOGINUID_LEGACY;
452 }
453
454 err = audit_field_valid(entry, f);
455 if (err)
456 goto exit_free;
457
458 err = -EINVAL;
459 switch (f->type) {
460 case AUDIT_LOGINUID:
461 case AUDIT_UID:
462 case AUDIT_EUID:
463 case AUDIT_SUID:
464 case AUDIT_FSUID:
465 case AUDIT_OBJ_UID:
466 f->uid = make_kuid(current_user_ns(), f->val);
467 if (!uid_valid(f->uid))
468 goto exit_free;
469 break;
470 case AUDIT_GID:
471 case AUDIT_EGID:
472 case AUDIT_SGID:
473 case AUDIT_FSGID:
474 case AUDIT_OBJ_GID:
475 f->gid = make_kgid(current_user_ns(), f->val);
476 if (!gid_valid(f->gid))
477 goto exit_free;
478 break;
479 case AUDIT_ARCH:
480 entry->rule.arch_f = f;
481 break;
482 case AUDIT_SUBJ_USER:
483 case AUDIT_SUBJ_ROLE:
484 case AUDIT_SUBJ_TYPE:
485 case AUDIT_SUBJ_SEN:
486 case AUDIT_SUBJ_CLR:
487 case AUDIT_OBJ_USER:
488 case AUDIT_OBJ_ROLE:
489 case AUDIT_OBJ_TYPE:
490 case AUDIT_OBJ_LEV_LOW:
491 case AUDIT_OBJ_LEV_HIGH:
492 str = audit_unpack_string(&bufp, &remain, f->val);
493 if (IS_ERR(str))
494 goto exit_free;
495 entry->rule.buflen += f->val;
496
497 err = security_audit_rule_init(f->type, f->op, str,
498 (void **)&f->lsm_rule);
499 /* Keep currently invalid fields around in case they
500 * become valid after a policy reload. */
501 if (err == -EINVAL) {
502 pr_warn("audit rule for LSM \'%s\' is invalid\n",
503 str);
504 err = 0;
505 }
506 if (err) {
507 kfree(str);
508 goto exit_free;
509 } else
510 f->lsm_str = str;
511 break;
512 case AUDIT_WATCH:
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_to_watch(&entry->rule, str, f->val, f->op);
519 if (err) {
520 kfree(str);
521 goto exit_free;
522 }
523 break;
524 case AUDIT_DIR:
525 str = audit_unpack_string(&bufp, &remain, f->val);
526 if (IS_ERR(str))
527 goto exit_free;
528 entry->rule.buflen += f->val;
529
530 err = audit_make_tree(&entry->rule, str, f->op);
531 kfree(str);
532 if (err)
533 goto exit_free;
534 break;
535 case AUDIT_INODE:
536 err = audit_to_inode(&entry->rule, f);
537 if (err)
538 goto exit_free;
539 break;
540 case AUDIT_FILTERKEY:
541 if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
542 goto exit_free;
543 str = audit_unpack_string(&bufp, &remain, f->val);
544 if (IS_ERR(str))
545 goto exit_free;
546 entry->rule.buflen += f->val;
547 entry->rule.filterkey = str;
548 break;
549 case AUDIT_EXE:
550 if (entry->rule.exe || f->val > PATH_MAX)
551 goto exit_free;
552 str = audit_unpack_string(&bufp, &remain, f->val);
553 if (IS_ERR(str)) {
554 err = PTR_ERR(str);
555 goto exit_free;
556 }
557 entry->rule.buflen += f->val;
558
559 audit_mark = audit_alloc_mark(&entry->rule, str, f->val);
560 if (IS_ERR(audit_mark)) {
561 kfree(str);
562 err = PTR_ERR(audit_mark);
563 goto exit_free;
564 }
565 entry->rule.exe = audit_mark;
566 break;
567 }
568 }
569
570 if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
571 entry->rule.inode_f = NULL;
572
573exit_nofree:
574 return entry;
575
576exit_free:
577 if (entry->rule.tree)
578 audit_put_tree(entry->rule.tree); /* that's the temporary one */
579 if (entry->rule.exe)
580 audit_remove_mark(entry->rule.exe); /* that's the template one */
581 audit_free_rule(entry);
582 return ERR_PTR(err);
583}
584
585/* Pack a filter field's string representation into data block. */
586static inline size_t audit_pack_string(void **bufp, const char *str)
587{
588 size_t len = strlen(str);
589
590 memcpy(*bufp, str, len);
591 *bufp += len;
592
593 return len;
594}
595
596/* Translate kernel rule representation to struct audit_rule_data. */
597static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
598{
599 struct audit_rule_data *data;
600 void *bufp;
601 int i;
602
603 data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
604 if (unlikely(!data))
605 return NULL;
606 memset(data, 0, sizeof(*data));
607
608 data->flags = krule->flags | krule->listnr;
609 data->action = krule->action;
610 data->field_count = krule->field_count;
611 bufp = data->buf;
612 for (i = 0; i < data->field_count; i++) {
613 struct audit_field *f = &krule->fields[i];
614
615 data->fields[i] = f->type;
616 data->fieldflags[i] = audit_ops[f->op];
617 switch(f->type) {
618 case AUDIT_SUBJ_USER:
619 case AUDIT_SUBJ_ROLE:
620 case AUDIT_SUBJ_TYPE:
621 case AUDIT_SUBJ_SEN:
622 case AUDIT_SUBJ_CLR:
623 case AUDIT_OBJ_USER:
624 case AUDIT_OBJ_ROLE:
625 case AUDIT_OBJ_TYPE:
626 case AUDIT_OBJ_LEV_LOW:
627 case AUDIT_OBJ_LEV_HIGH:
628 data->buflen += data->values[i] =
629 audit_pack_string(&bufp, f->lsm_str);
630 break;
631 case AUDIT_WATCH:
632 data->buflen += data->values[i] =
633 audit_pack_string(&bufp,
634 audit_watch_path(krule->watch));
635 break;
636 case AUDIT_DIR:
637 data->buflen += data->values[i] =
638 audit_pack_string(&bufp,
639 audit_tree_path(krule->tree));
640 break;
641 case AUDIT_FILTERKEY:
642 data->buflen += data->values[i] =
643 audit_pack_string(&bufp, krule->filterkey);
644 break;
645 case AUDIT_EXE:
646 data->buflen += data->values[i] =
647 audit_pack_string(&bufp, audit_mark_path(krule->exe));
648 break;
649 case AUDIT_LOGINUID_SET:
650 if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) {
651 data->fields[i] = AUDIT_LOGINUID;
652 data->values[i] = AUDIT_UID_UNSET;
653 break;
654 }
655 /* fallthrough if set */
656 default:
657 data->values[i] = f->val;
658 }
659 }
660 for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];
661
662 return data;
663}
664
665/* Compare two rules in kernel format. Considered success if rules
666 * don't match. */
667static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
668{
669 int i;
670
671 if (a->flags != b->flags ||
672 a->pflags != b->pflags ||
673 a->listnr != b->listnr ||
674 a->action != b->action ||
675 a->field_count != b->field_count)
676 return 1;
677
678 for (i = 0; i < a->field_count; i++) {
679 if (a->fields[i].type != b->fields[i].type ||
680 a->fields[i].op != b->fields[i].op)
681 return 1;
682
683 switch(a->fields[i].type) {
684 case AUDIT_SUBJ_USER:
685 case AUDIT_SUBJ_ROLE:
686 case AUDIT_SUBJ_TYPE:
687 case AUDIT_SUBJ_SEN:
688 case AUDIT_SUBJ_CLR:
689 case AUDIT_OBJ_USER:
690 case AUDIT_OBJ_ROLE:
691 case AUDIT_OBJ_TYPE:
692 case AUDIT_OBJ_LEV_LOW:
693 case AUDIT_OBJ_LEV_HIGH:
694 if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
695 return 1;
696 break;
697 case AUDIT_WATCH:
698 if (strcmp(audit_watch_path(a->watch),
699 audit_watch_path(b->watch)))
700 return 1;
701 break;
702 case AUDIT_DIR:
703 if (strcmp(audit_tree_path(a->tree),
704 audit_tree_path(b->tree)))
705 return 1;
706 break;
707 case AUDIT_FILTERKEY:
708 /* both filterkeys exist based on above type compare */
709 if (strcmp(a->filterkey, b->filterkey))
710 return 1;
711 break;
712 case AUDIT_EXE:
713 /* both paths exist based on above type compare */
714 if (strcmp(audit_mark_path(a->exe),
715 audit_mark_path(b->exe)))
716 return 1;
717 break;
718 case AUDIT_UID:
719 case AUDIT_EUID:
720 case AUDIT_SUID:
721 case AUDIT_FSUID:
722 case AUDIT_LOGINUID:
723 case AUDIT_OBJ_UID:
724 if (!uid_eq(a->fields[i].uid, b->fields[i].uid))
725 return 1;
726 break;
727 case AUDIT_GID:
728 case AUDIT_EGID:
729 case AUDIT_SGID:
730 case AUDIT_FSGID:
731 case AUDIT_OBJ_GID:
732 if (!gid_eq(a->fields[i].gid, b->fields[i].gid))
733 return 1;
734 break;
735 default:
736 if (a->fields[i].val != b->fields[i].val)
737 return 1;
738 }
739 }
740
741 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
742 if (a->mask[i] != b->mask[i])
743 return 1;
744
745 return 0;
746}
747
748/* Duplicate LSM field information. The lsm_rule is opaque, so must be
749 * re-initialized. */
750static inline int audit_dupe_lsm_field(struct audit_field *df,
751 struct audit_field *sf)
752{
753 int ret = 0;
754 char *lsm_str;
755
756 /* our own copy of lsm_str */
757 lsm_str = kstrdup(sf->lsm_str, GFP_KERNEL);
758 if (unlikely(!lsm_str))
759 return -ENOMEM;
760 df->lsm_str = lsm_str;
761
762 /* our own (refreshed) copy of lsm_rule */
763 ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
764 (void **)&df->lsm_rule);
765 /* Keep currently invalid fields around in case they
766 * become valid after a policy reload. */
767 if (ret == -EINVAL) {
768 pr_warn("audit rule for LSM \'%s\' is invalid\n",
769 df->lsm_str);
770 ret = 0;
771 }
772
773 return ret;
774}
775
776/* Duplicate an audit rule. This will be a deep copy with the exception
777 * of the watch - that pointer is carried over. The LSM specific fields
778 * will be updated in the copy. The point is to be able to replace the old
779 * rule with the new rule in the filterlist, then free the old rule.
780 * The rlist element is undefined; list manipulations are handled apart from
781 * the initial copy. */
782struct audit_entry *audit_dupe_rule(struct audit_krule *old)
783{
784 u32 fcount = old->field_count;
785 struct audit_entry *entry;
786 struct audit_krule *new;
787 char *fk;
788 int i, err = 0;
789
790 entry = audit_init_entry(fcount);
791 if (unlikely(!entry))
792 return ERR_PTR(-ENOMEM);
793
794 new = &entry->rule;
795 new->flags = old->flags;
796 new->pflags = old->pflags;
797 new->listnr = old->listnr;
798 new->action = old->action;
799 for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
800 new->mask[i] = old->mask[i];
801 new->prio = old->prio;
802 new->buflen = old->buflen;
803 new->inode_f = old->inode_f;
804 new->field_count = old->field_count;
805
806 /*
807 * note that we are OK with not refcounting here; audit_match_tree()
808 * never dereferences tree and we can't get false positives there
809 * since we'd have to have rule gone from the list *and* removed
810 * before the chunks found by lookup had been allocated, i.e. before
811 * the beginning of list scan.
812 */
813 new->tree = old->tree;
814 memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);
815
816 /* deep copy this information, updating the lsm_rule fields, because
817 * the originals will all be freed when the old rule is freed. */
818 for (i = 0; i < fcount; i++) {
819 switch (new->fields[i].type) {
820 case AUDIT_SUBJ_USER:
821 case AUDIT_SUBJ_ROLE:
822 case AUDIT_SUBJ_TYPE:
823 case AUDIT_SUBJ_SEN:
824 case AUDIT_SUBJ_CLR:
825 case AUDIT_OBJ_USER:
826 case AUDIT_OBJ_ROLE:
827 case AUDIT_OBJ_TYPE:
828 case AUDIT_OBJ_LEV_LOW:
829 case AUDIT_OBJ_LEV_HIGH:
830 err = audit_dupe_lsm_field(&new->fields[i],
831 &old->fields[i]);
832 break;
833 case AUDIT_FILTERKEY:
834 fk = kstrdup(old->filterkey, GFP_KERNEL);
835 if (unlikely(!fk))
836 err = -ENOMEM;
837 else
838 new->filterkey = fk;
839 break;
840 case AUDIT_EXE:
841 err = audit_dupe_exe(new, old);
842 break;
843 }
844 if (err) {
845 if (new->exe)
846 audit_remove_mark(new->exe);
847 audit_free_rule(entry);
848 return ERR_PTR(err);
849 }
850 }
851
852 if (old->watch) {
853 audit_get_watch(old->watch);
854 new->watch = old->watch;
855 }
856
857 return entry;
858}
859
860/* Find an existing audit rule.
861 * Caller must hold audit_filter_mutex to prevent stale rule data. */
862static struct audit_entry *audit_find_rule(struct audit_entry *entry,
863 struct list_head **p)
864{
865 struct audit_entry *e, *found = NULL;
866 struct list_head *list;
867 int h;
868
869 if (entry->rule.inode_f) {
870 h = audit_hash_ino(entry->rule.inode_f->val);
871 *p = list = &audit_inode_hash[h];
872 } else if (entry->rule.watch) {
873 /* we don't know the inode number, so must walk entire hash */
874 for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
875 list = &audit_inode_hash[h];
876 list_for_each_entry(e, list, list)
877 if (!audit_compare_rule(&entry->rule, &e->rule)) {
878 found = e;
879 goto out;
880 }
881 }
882 goto out;
883 } else {
884 *p = list = &audit_filter_list[entry->rule.listnr];
885 }
886
887 list_for_each_entry(e, list, list)
888 if (!audit_compare_rule(&entry->rule, &e->rule)) {
889 found = e;
890 goto out;
891 }
892
893out:
894 return found;
895}
896
897static u64 prio_low = ~0ULL/2;
898static u64 prio_high = ~0ULL/2 - 1;
899
900/* Add rule to given filterlist if not a duplicate. */
901static inline int audit_add_rule(struct audit_entry *entry)
902{
903 struct audit_entry *e;
904 struct audit_watch *watch = entry->rule.watch;
905 struct audit_tree *tree = entry->rule.tree;
906 struct list_head *list;
907 int err = 0;
908#ifdef CONFIG_AUDITSYSCALL
909 int dont_count = 0;
910
911 /* If either of these, don't count towards total */
912 if (entry->rule.listnr == AUDIT_FILTER_USER ||
913 entry->rule.listnr == AUDIT_FILTER_TYPE)
914 dont_count = 1;
915#endif
916
917 mutex_lock(&audit_filter_mutex);
918 e = audit_find_rule(entry, &list);
919 if (e) {
920 mutex_unlock(&audit_filter_mutex);
921 err = -EEXIST;
922 /* normally audit_add_tree_rule() will free it on failure */
923 if (tree)
924 audit_put_tree(tree);
925 return err;
926 }
927
928 if (watch) {
929 /* audit_filter_mutex is dropped and re-taken during this call */
930 err = audit_add_watch(&entry->rule, &list);
931 if (err) {
932 mutex_unlock(&audit_filter_mutex);
933 /*
934 * normally audit_add_tree_rule() will free it
935 * on failure
936 */
937 if (tree)
938 audit_put_tree(tree);
939 return err;
940 }
941 }
942 if (tree) {
943 err = audit_add_tree_rule(&entry->rule);
944 if (err) {
945 mutex_unlock(&audit_filter_mutex);
946 return err;
947 }
948 }
949
950 entry->rule.prio = ~0ULL;
951 if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
952 if (entry->rule.flags & AUDIT_FILTER_PREPEND)
953 entry->rule.prio = ++prio_high;
954 else
955 entry->rule.prio = --prio_low;
956 }
957
958 if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
959 list_add(&entry->rule.list,
960 &audit_rules_list[entry->rule.listnr]);
961 list_add_rcu(&entry->list, list);
962 entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
963 } else {
964 list_add_tail(&entry->rule.list,
965 &audit_rules_list[entry->rule.listnr]);
966 list_add_tail_rcu(&entry->list, list);
967 }
968#ifdef CONFIG_AUDITSYSCALL
969 if (!dont_count)
970 audit_n_rules++;
971
972 if (!audit_match_signal(entry))
973 audit_signals++;
974#endif
975 mutex_unlock(&audit_filter_mutex);
976
977 return err;
978}
979
980/* Remove an existing rule from filterlist. */
981int audit_del_rule(struct audit_entry *entry)
982{
983 struct audit_entry *e;
984 struct audit_tree *tree = entry->rule.tree;
985 struct list_head *list;
986 int ret = 0;
987#ifdef CONFIG_AUDITSYSCALL
988 int dont_count = 0;
989
990 /* If either of these, don't count towards total */
991 if (entry->rule.listnr == AUDIT_FILTER_USER ||
992 entry->rule.listnr == AUDIT_FILTER_TYPE)
993 dont_count = 1;
994#endif
995
996 mutex_lock(&audit_filter_mutex);
997 e = audit_find_rule(entry, &list);
998 if (!e) {
999 ret = -ENOENT;
1000 goto out;
1001 }
1002
1003 if (e->rule.watch)
1004 audit_remove_watch_rule(&e->rule);
1005
1006 if (e->rule.tree)
1007 audit_remove_tree_rule(&e->rule);
1008
1009 if (e->rule.exe)
1010 audit_remove_mark_rule(&e->rule);
1011
1012#ifdef CONFIG_AUDITSYSCALL
1013 if (!dont_count)
1014 audit_n_rules--;
1015
1016 if (!audit_match_signal(entry))
1017 audit_signals--;
1018#endif
1019
1020 list_del_rcu(&e->list);
1021 list_del(&e->rule.list);
1022 call_rcu(&e->rcu, audit_free_rule_rcu);
1023
1024out:
1025 mutex_unlock(&audit_filter_mutex);
1026
1027 if (tree)
1028 audit_put_tree(tree); /* that's the temporary one */
1029
1030 return ret;
1031}
1032
1033/* List rules using struct audit_rule_data. */
1034static void audit_list_rules(__u32 portid, int seq, struct sk_buff_head *q)
1035{
1036 struct sk_buff *skb;
1037 struct audit_krule *r;
1038 int i;
1039
1040 /* This is a blocking read, so use audit_filter_mutex instead of rcu
1041 * iterator to sync with list writers. */
1042 for (i=0; i<AUDIT_NR_FILTERS; i++) {
1043 list_for_each_entry(r, &audit_rules_list[i], list) {
1044 struct audit_rule_data *data;
1045
1046 data = audit_krule_to_data(r);
1047 if (unlikely(!data))
1048 break;
1049 skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES,
1050 0, 1, data,
1051 sizeof(*data) + data->buflen);
1052 if (skb)
1053 skb_queue_tail(q, skb);
1054 kfree(data);
1055 }
1056 }
1057 skb = audit_make_reply(portid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
1058 if (skb)
1059 skb_queue_tail(q, skb);
1060}
1061
1062/* Log rule additions and removals */
1063static void audit_log_rule_change(char *action, struct audit_krule *rule, int res)
1064{
1065 struct audit_buffer *ab;
1066 uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));
1067 unsigned int sessionid = audit_get_sessionid(current);
1068
1069 if (!audit_enabled)
1070 return;
1071
1072 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
1073 if (!ab)
1074 return;
1075 audit_log_format(ab, "auid=%u ses=%u" ,loginuid, sessionid);
1076 audit_log_task_context(ab);
1077 audit_log_format(ab, " op=");
1078 audit_log_string(ab, action);
1079 audit_log_key(ab, rule->filterkey);
1080 audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
1081 audit_log_end(ab);
1082}
1083
1084/**
1085 * audit_rule_change - apply all rules to the specified message type
1086 * @type: audit message type
1087 * @portid: target port id for netlink audit messages
1088 * @seq: netlink audit message sequence (serial) number
1089 * @data: payload data
1090 * @datasz: size of payload data
1091 */
1092int audit_rule_change(int type, __u32 portid, int seq, void *data,
1093 size_t datasz)
1094{
1095 int err = 0;
1096 struct audit_entry *entry;
1097
1098 switch (type) {
1099 case AUDIT_ADD_RULE:
1100 entry = audit_data_to_entry(data, datasz);
1101 if (IS_ERR(entry))
1102 return PTR_ERR(entry);
1103 err = audit_add_rule(entry);
1104 audit_log_rule_change("add_rule", &entry->rule, !err);
1105 break;
1106 case AUDIT_DEL_RULE:
1107 entry = audit_data_to_entry(data, datasz);
1108 if (IS_ERR(entry))
1109 return PTR_ERR(entry);
1110 err = audit_del_rule(entry);
1111 audit_log_rule_change("remove_rule", &entry->rule, !err);
1112 break;
1113 default:
1114 WARN_ON(1);
1115 return -EINVAL;
1116 }
1117
1118 if (err || type == AUDIT_DEL_RULE) {
1119 if (entry->rule.exe)
1120 audit_remove_mark(entry->rule.exe);
1121 audit_free_rule(entry);
1122 }
1123
1124 return err;
1125}
1126
1127/**
1128 * audit_list_rules_send - list the audit rules
1129 * @request_skb: skb of request we are replying to (used to target the reply)
1130 * @seq: netlink audit message sequence (serial) number
1131 */
1132int audit_list_rules_send(struct sk_buff *request_skb, int seq)
1133{
1134 u32 portid = NETLINK_CB(request_skb).portid;
1135 struct net *net = sock_net(NETLINK_CB(request_skb).sk);
1136 struct task_struct *tsk;
1137 struct audit_netlink_list *dest;
1138 int err = 0;
1139
1140 /* We can't just spew out the rules here because we might fill
1141 * the available socket buffer space and deadlock waiting for
1142 * auditctl to read from it... which isn't ever going to
1143 * happen if we're actually running in the context of auditctl
1144 * trying to _send_ the stuff */
1145
1146 dest = kmalloc(sizeof(struct audit_netlink_list), GFP_KERNEL);
1147 if (!dest)
1148 return -ENOMEM;
1149 dest->net = get_net(net);
1150 dest->portid = portid;
1151 skb_queue_head_init(&dest->q);
1152
1153 mutex_lock(&audit_filter_mutex);
1154 audit_list_rules(portid, seq, &dest->q);
1155 mutex_unlock(&audit_filter_mutex);
1156
1157 tsk = kthread_run(audit_send_list, dest, "audit_send_list");
1158 if (IS_ERR(tsk)) {
1159 skb_queue_purge(&dest->q);
1160 kfree(dest);
1161 err = PTR_ERR(tsk);
1162 }
1163
1164 return err;
1165}
1166
1167int audit_comparator(u32 left, u32 op, u32 right)
1168{
1169 switch (op) {
1170 case Audit_equal:
1171 return (left == right);
1172 case Audit_not_equal:
1173 return (left != right);
1174 case Audit_lt:
1175 return (left < right);
1176 case Audit_le:
1177 return (left <= right);
1178 case Audit_gt:
1179 return (left > right);
1180 case Audit_ge:
1181 return (left >= right);
1182 case Audit_bitmask:
1183 return (left & right);
1184 case Audit_bittest:
1185 return ((left & right) == right);
1186 default:
1187 BUG();
1188 return 0;
1189 }
1190}
1191
1192int audit_uid_comparator(kuid_t left, u32 op, kuid_t right)
1193{
1194 switch (op) {
1195 case Audit_equal:
1196 return uid_eq(left, right);
1197 case Audit_not_equal:
1198 return !uid_eq(left, right);
1199 case Audit_lt:
1200 return uid_lt(left, right);
1201 case Audit_le:
1202 return uid_lte(left, right);
1203 case Audit_gt:
1204 return uid_gt(left, right);
1205 case Audit_ge:
1206 return uid_gte(left, right);
1207 case Audit_bitmask:
1208 case Audit_bittest:
1209 default:
1210 BUG();
1211 return 0;
1212 }
1213}
1214
1215int audit_gid_comparator(kgid_t left, u32 op, kgid_t right)
1216{
1217 switch (op) {
1218 case Audit_equal:
1219 return gid_eq(left, right);
1220 case Audit_not_equal:
1221 return !gid_eq(left, right);
1222 case Audit_lt:
1223 return gid_lt(left, right);
1224 case Audit_le:
1225 return gid_lte(left, right);
1226 case Audit_gt:
1227 return gid_gt(left, right);
1228 case Audit_ge:
1229 return gid_gte(left, right);
1230 case Audit_bitmask:
1231 case Audit_bittest:
1232 default:
1233 BUG();
1234 return 0;
1235 }
1236}
1237
1238/**
1239 * parent_len - find the length of the parent portion of a pathname
1240 * @path: pathname of which to determine length
1241 */
1242int parent_len(const char *path)
1243{
1244 int plen;
1245 const char *p;
1246
1247 plen = strlen(path);
1248
1249 if (plen == 0)
1250 return plen;
1251
1252 /* disregard trailing slashes */
1253 p = path + plen - 1;
1254 while ((*p == '/') && (p > path))
1255 p--;
1256
1257 /* walk backward until we find the next slash or hit beginning */
1258 while ((*p != '/') && (p > path))
1259 p--;
1260
1261 /* did we find a slash? Then increment to include it in path */
1262 if (*p == '/')
1263 p++;
1264
1265 return p - path;
1266}
1267
1268/**
1269 * audit_compare_dname_path - compare given dentry name with last component in
1270 * given path. Return of 0 indicates a match.
1271 * @dname: dentry name that we're comparing
1272 * @path: full pathname that we're comparing
1273 * @parentlen: length of the parent if known. Passing in AUDIT_NAME_FULL
1274 * here indicates that we must compute this value.
1275 */
1276int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
1277{
1278 int dlen, pathlen;
1279 const char *p;
1280
1281 dlen = strlen(dname);
1282 pathlen = strlen(path);
1283 if (pathlen < dlen)
1284 return 1;
1285
1286 parentlen = parentlen == AUDIT_NAME_FULL ? parent_len(path) : parentlen;
1287 if (pathlen - parentlen != dlen)
1288 return 1;
1289
1290 p = path + parentlen;
1291
1292 return strncmp(p, dname, dlen);
1293}
1294
1295int audit_filter(int msgtype, unsigned int listtype)
1296{
1297 struct audit_entry *e;
1298 int ret = 1; /* Audit by default */
1299
1300 rcu_read_lock();
1301 if (list_empty(&audit_filter_list[listtype]))
1302 goto unlock_and_return;
1303 list_for_each_entry_rcu(e, &audit_filter_list[listtype], list) {
1304 int i, result = 0;
1305
1306 for (i = 0; i < e->rule.field_count; i++) {
1307 struct audit_field *f = &e->rule.fields[i];
1308 pid_t pid;
1309 u32 sid;
1310
1311 switch (f->type) {
1312 case AUDIT_PID:
1313 pid = task_pid_nr(current);
1314 result = audit_comparator(pid, f->op, f->val);
1315 break;
1316 case AUDIT_UID:
1317 result = audit_uid_comparator(current_uid(), f->op, f->uid);
1318 break;
1319 case AUDIT_GID:
1320 result = audit_gid_comparator(current_gid(), f->op, f->gid);
1321 break;
1322 case AUDIT_LOGINUID:
1323 result = audit_uid_comparator(audit_get_loginuid(current),
1324 f->op, f->uid);
1325 break;
1326 case AUDIT_LOGINUID_SET:
1327 result = audit_comparator(audit_loginuid_set(current),
1328 f->op, f->val);
1329 break;
1330 case AUDIT_MSGTYPE:
1331 result = audit_comparator(msgtype, f->op, f->val);
1332 break;
1333 case AUDIT_SUBJ_USER:
1334 case AUDIT_SUBJ_ROLE:
1335 case AUDIT_SUBJ_TYPE:
1336 case AUDIT_SUBJ_SEN:
1337 case AUDIT_SUBJ_CLR:
1338 if (f->lsm_rule) {
1339 security_task_getsecid(current, &sid);
1340 result = security_audit_rule_match(sid,
1341 f->type, f->op, f->lsm_rule, NULL);
1342 }
1343 break;
1344 default:
1345 goto unlock_and_return;
1346 }
1347 if (result < 0) /* error */
1348 goto unlock_and_return;
1349 if (!result)
1350 break;
1351 }
1352 if (result > 0) {
1353 if (e->rule.action == AUDIT_NEVER || listtype == AUDIT_FILTER_TYPE)
1354 ret = 0;
1355 break;
1356 }
1357 }
1358unlock_and_return:
1359 rcu_read_unlock();
1360 return ret;
1361}
1362
1363static int update_lsm_rule(struct audit_krule *r)
1364{
1365 struct audit_entry *entry = container_of(r, struct audit_entry, rule);
1366 struct audit_entry *nentry;
1367 int err = 0;
1368
1369 if (!security_audit_rule_known(r))
1370 return 0;
1371
1372 nentry = audit_dupe_rule(r);
1373 if (entry->rule.exe)
1374 audit_remove_mark(entry->rule.exe);
1375 if (IS_ERR(nentry)) {
1376 /* save the first error encountered for the
1377 * return value */
1378 err = PTR_ERR(nentry);
1379 audit_panic("error updating LSM filters");
1380 if (r->watch)
1381 list_del(&r->rlist);
1382 list_del_rcu(&entry->list);
1383 list_del(&r->list);
1384 } else {
1385 if (r->watch || r->tree)
1386 list_replace_init(&r->rlist, &nentry->rule.rlist);
1387 list_replace_rcu(&entry->list, &nentry->list);
1388 list_replace(&r->list, &nentry->rule.list);
1389 }
1390 call_rcu(&entry->rcu, audit_free_rule_rcu);
1391
1392 return err;
1393}
1394
1395/* This function will re-initialize the lsm_rule field of all applicable rules.
1396 * It will traverse the filter lists serarching for rules that contain LSM
1397 * specific filter fields. When such a rule is found, it is copied, the
1398 * LSM field is re-initialized, and the old rule is replaced with the
1399 * updated rule. */
1400int audit_update_lsm_rules(void)
1401{
1402 struct audit_krule *r, *n;
1403 int i, err = 0;
1404
1405 /* audit_filter_mutex synchronizes the writers */
1406 mutex_lock(&audit_filter_mutex);
1407
1408 for (i = 0; i < AUDIT_NR_FILTERS; i++) {
1409 list_for_each_entry_safe(r, n, &audit_rules_list[i], list) {
1410 int res = update_lsm_rule(r);
1411 if (!err)
1412 err = res;
1413 }
1414 }
1415 mutex_unlock(&audit_filter_mutex);
1416
1417 return err;
1418}
1419
generated by cgit at 2024-05-18 13:50:27 (GMT)