xHCI: set USB2 hardware LPM
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / security / tomoyo / gc.c
blobae135fbbbe955b922c0fe3dbe6d8d158dc6fa9d1
1 /*
2 * security/tomoyo/gc.c
4 * Copyright (C) 2005-2011 NTT DATA CORPORATION
5 */
7 #include "common.h"
8 #include <linux/kthread.h>
9 #include <linux/slab.h>
11 /* The list for "struct tomoyo_io_buffer". */
12 static LIST_HEAD(tomoyo_io_buffer_list);
13 /* Lock for protecting tomoyo_io_buffer_list. */
14 static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);
16 /* Size of an element. */
17 static const u8 tomoyo_element_size[TOMOYO_MAX_POLICY] = {
18 [TOMOYO_ID_GROUP] = sizeof(struct tomoyo_group),
19 [TOMOYO_ID_PATH_GROUP] = sizeof(struct tomoyo_path_group),
20 [TOMOYO_ID_NUMBER_GROUP] = sizeof(struct tomoyo_number_group),
21 [TOMOYO_ID_AGGREGATOR] = sizeof(struct tomoyo_aggregator),
22 [TOMOYO_ID_TRANSITION_CONTROL] =
23 sizeof(struct tomoyo_transition_control),
24 [TOMOYO_ID_MANAGER] = sizeof(struct tomoyo_manager),
25 /* [TOMOYO_ID_CONDITION] = "struct tomoyo_condition"->size, */
26 /* [TOMOYO_ID_NAME] = "struct tomoyo_name"->size, */
27 /* [TOMOYO_ID_ACL] =
28 tomoyo_acl_size["struct tomoyo_acl_info"->type], */
29 [TOMOYO_ID_DOMAIN] = sizeof(struct tomoyo_domain_info),
32 /* Size of a domain ACL element. */
33 static const u8 tomoyo_acl_size[] = {
34 [TOMOYO_TYPE_PATH_ACL] = sizeof(struct tomoyo_path_acl),
35 [TOMOYO_TYPE_PATH2_ACL] = sizeof(struct tomoyo_path2_acl),
36 [TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl),
37 [TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl),
38 [TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl),
41 /**
42 * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
44 * @element: Pointer to "struct list_head".
46 * Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
47 * false otherwise.
49 static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
51 struct tomoyo_io_buffer *head;
52 bool in_use = false;
54 spin_lock(&tomoyo_io_buffer_list_lock);
55 list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
56 head->users++;
57 spin_unlock(&tomoyo_io_buffer_list_lock);
58 if (mutex_lock_interruptible(&head->io_sem)) {
59 in_use = true;
60 goto out;
62 if (head->r.domain == element || head->r.group == element ||
63 head->r.acl == element || &head->w.domain->list == element)
64 in_use = true;
65 mutex_unlock(&head->io_sem);
66 out:
67 spin_lock(&tomoyo_io_buffer_list_lock);
68 head->users--;
69 if (in_use)
70 break;
72 spin_unlock(&tomoyo_io_buffer_list_lock);
73 return in_use;
76 /**
77 * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.
79 * @string: String to check.
80 * @size: Memory allocated for @string .
82 * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,
83 * false otherwise.
85 static bool tomoyo_name_used_by_io_buffer(const char *string,
86 const size_t size)
88 struct tomoyo_io_buffer *head;
89 bool in_use = false;
91 spin_lock(&tomoyo_io_buffer_list_lock);
92 list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
93 int i;
94 head->users++;
95 spin_unlock(&tomoyo_io_buffer_list_lock);
96 if (mutex_lock_interruptible(&head->io_sem)) {
97 in_use = true;
98 goto out;
100 for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {
101 const char *w = head->r.w[i];
102 if (w < string || w > string + size)
103 continue;
104 in_use = true;
105 break;
107 mutex_unlock(&head->io_sem);
108 out:
109 spin_lock(&tomoyo_io_buffer_list_lock);
110 head->users--;
111 if (in_use)
112 break;
114 spin_unlock(&tomoyo_io_buffer_list_lock);
115 return in_use;
118 /* Structure for garbage collection. */
119 struct tomoyo_gc {
120 struct list_head list;
121 enum tomoyo_policy_id type;
122 size_t size;
123 struct list_head *element;
125 /* List of entries to be deleted. */
126 static LIST_HEAD(tomoyo_gc_list);
127 /* Length of tomoyo_gc_list. */
128 static int tomoyo_gc_list_len;
131 * tomoyo_add_to_gc - Add an entry to to be deleted list.
133 * @type: One of values in "enum tomoyo_policy_id".
134 * @element: Pointer to "struct list_head".
136 * Returns true on success, false otherwise.
138 * Caller holds tomoyo_policy_lock mutex.
140 * Adding an entry needs kmalloc(). Thus, if we try to add thousands of
141 * entries at once, it will take too long time. Thus, do not add more than 128
142 * entries per a scan. But to be able to handle worst case where all entries
143 * are in-use, we accept one more entry per a scan.
145 * If we use singly linked list using "struct list_head"->prev (which is
146 * LIST_POISON2), we can avoid kmalloc().
148 static bool tomoyo_add_to_gc(const int type, struct list_head *element)
150 struct tomoyo_gc *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
151 if (!entry)
152 return false;
153 entry->type = type;
154 if (type == TOMOYO_ID_ACL)
155 entry->size = tomoyo_acl_size[
156 container_of(element,
157 typeof(struct tomoyo_acl_info),
158 list)->type];
159 else if (type == TOMOYO_ID_NAME)
160 entry->size = strlen(container_of(element,
161 typeof(struct tomoyo_name),
162 head.list)->entry.name) + 1;
163 else if (type == TOMOYO_ID_CONDITION)
164 entry->size =
165 container_of(element, typeof(struct tomoyo_condition),
166 head.list)->size;
167 else
168 entry->size = tomoyo_element_size[type];
169 entry->element = element;
170 list_add(&entry->list, &tomoyo_gc_list);
171 list_del_rcu(element);
172 return tomoyo_gc_list_len++ < 128;
176 * tomoyo_element_linked_by_gc - Validate next element of an entry.
178 * @element: Pointer to an element.
179 * @size: Size of @element in byte.
181 * Returns true if @element is linked by other elements in the garbage
182 * collector's queue, false otherwise.
184 static bool tomoyo_element_linked_by_gc(const u8 *element, const size_t size)
186 struct tomoyo_gc *p;
187 list_for_each_entry(p, &tomoyo_gc_list, list) {
188 const u8 *ptr = (const u8 *) p->element->next;
189 if (ptr < element || element + size < ptr)
190 continue;
191 return true;
193 return false;
197 * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
199 * @element: Pointer to "struct list_head".
201 * Returns nothing.
203 static void tomoyo_del_transition_control(struct list_head *element)
205 struct tomoyo_transition_control *ptr =
206 container_of(element, typeof(*ptr), head.list);
207 tomoyo_put_name(ptr->domainname);
208 tomoyo_put_name(ptr->program);
212 * tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
214 * @element: Pointer to "struct list_head".
216 * Returns nothing.
218 static void tomoyo_del_aggregator(struct list_head *element)
220 struct tomoyo_aggregator *ptr =
221 container_of(element, typeof(*ptr), head.list);
222 tomoyo_put_name(ptr->original_name);
223 tomoyo_put_name(ptr->aggregated_name);
227 * tomoyo_del_manager - Delete members in "struct tomoyo_manager".
229 * @element: Pointer to "struct list_head".
231 * Returns nothing.
233 static void tomoyo_del_manager(struct list_head *element)
235 struct tomoyo_manager *ptr =
236 container_of(element, typeof(*ptr), head.list);
237 tomoyo_put_name(ptr->manager);
241 * tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
243 * @element: Pointer to "struct list_head".
245 * Returns nothing.
247 static void tomoyo_del_acl(struct list_head *element)
249 struct tomoyo_acl_info *acl =
250 container_of(element, typeof(*acl), list);
251 tomoyo_put_condition(acl->cond);
252 switch (acl->type) {
253 case TOMOYO_TYPE_PATH_ACL:
255 struct tomoyo_path_acl *entry
256 = container_of(acl, typeof(*entry), head);
257 tomoyo_put_name_union(&entry->name);
259 break;
260 case TOMOYO_TYPE_PATH2_ACL:
262 struct tomoyo_path2_acl *entry
263 = container_of(acl, typeof(*entry), head);
264 tomoyo_put_name_union(&entry->name1);
265 tomoyo_put_name_union(&entry->name2);
267 break;
268 case TOMOYO_TYPE_PATH_NUMBER_ACL:
270 struct tomoyo_path_number_acl *entry
271 = container_of(acl, typeof(*entry), head);
272 tomoyo_put_name_union(&entry->name);
273 tomoyo_put_number_union(&entry->number);
275 break;
276 case TOMOYO_TYPE_MKDEV_ACL:
278 struct tomoyo_mkdev_acl *entry
279 = container_of(acl, typeof(*entry), head);
280 tomoyo_put_name_union(&entry->name);
281 tomoyo_put_number_union(&entry->mode);
282 tomoyo_put_number_union(&entry->major);
283 tomoyo_put_number_union(&entry->minor);
285 break;
286 case TOMOYO_TYPE_MOUNT_ACL:
288 struct tomoyo_mount_acl *entry
289 = container_of(acl, typeof(*entry), head);
290 tomoyo_put_name_union(&entry->dev_name);
291 tomoyo_put_name_union(&entry->dir_name);
292 tomoyo_put_name_union(&entry->fs_type);
293 tomoyo_put_number_union(&entry->flags);
295 break;
300 * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
302 * @element: Pointer to "struct list_head".
304 * Returns true if deleted, false otherwise.
306 static bool tomoyo_del_domain(struct list_head *element)
308 struct tomoyo_domain_info *domain =
309 container_of(element, typeof(*domain), list);
310 struct tomoyo_acl_info *acl;
311 struct tomoyo_acl_info *tmp;
313 * Since we don't protect whole execve() operation using SRCU,
314 * we need to recheck domain->users at this point.
316 * (1) Reader starts SRCU section upon execve().
317 * (2) Reader traverses tomoyo_domain_list and finds this domain.
318 * (3) Writer marks this domain as deleted.
319 * (4) Garbage collector removes this domain from tomoyo_domain_list
320 * because this domain is marked as deleted and used by nobody.
321 * (5) Reader saves reference to this domain into
322 * "struct linux_binprm"->cred->security .
323 * (6) Reader finishes SRCU section, although execve() operation has
324 * not finished yet.
325 * (7) Garbage collector waits for SRCU synchronization.
326 * (8) Garbage collector kfree() this domain because this domain is
327 * used by nobody.
328 * (9) Reader finishes execve() operation and restores this domain from
329 * "struct linux_binprm"->cred->security.
331 * By updating domain->users at (5), we can solve this race problem
332 * by rechecking domain->users at (8).
334 if (atomic_read(&domain->users))
335 return false;
336 list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
337 tomoyo_del_acl(&acl->list);
338 tomoyo_memory_free(acl);
340 tomoyo_put_name(domain->domainname);
341 return true;
345 * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
347 * @element: Pointer to "struct list_head".
349 * Returns nothing.
351 void tomoyo_del_condition(struct list_head *element)
353 struct tomoyo_condition *cond = container_of(element, typeof(*cond),
354 head.list);
355 const u16 condc = cond->condc;
356 const u16 numbers_count = cond->numbers_count;
357 const u16 names_count = cond->names_count;
358 const u16 argc = cond->argc;
359 const u16 envc = cond->envc;
360 unsigned int i;
361 const struct tomoyo_condition_element *condp
362 = (const struct tomoyo_condition_element *) (cond + 1);
363 struct tomoyo_number_union *numbers_p
364 = (struct tomoyo_number_union *) (condp + condc);
365 struct tomoyo_name_union *names_p
366 = (struct tomoyo_name_union *) (numbers_p + numbers_count);
367 const struct tomoyo_argv *argv
368 = (const struct tomoyo_argv *) (names_p + names_count);
369 const struct tomoyo_envp *envp
370 = (const struct tomoyo_envp *) (argv + argc);
371 for (i = 0; i < numbers_count; i++)
372 tomoyo_put_number_union(numbers_p++);
373 for (i = 0; i < names_count; i++)
374 tomoyo_put_name_union(names_p++);
375 for (i = 0; i < argc; argv++, i++)
376 tomoyo_put_name(argv->value);
377 for (i = 0; i < envc; envp++, i++) {
378 tomoyo_put_name(envp->name);
379 tomoyo_put_name(envp->value);
384 * tomoyo_del_name - Delete members in "struct tomoyo_name".
386 * @element: Pointer to "struct list_head".
388 * Returns nothing.
390 static void tomoyo_del_name(struct list_head *element)
392 const struct tomoyo_name *ptr =
393 container_of(element, typeof(*ptr), head.list);
397 * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
399 * @element: Pointer to "struct list_head".
401 * Returns nothing.
403 static void tomoyo_del_path_group(struct list_head *element)
405 struct tomoyo_path_group *member =
406 container_of(element, typeof(*member), head.list);
407 tomoyo_put_name(member->member_name);
411 * tomoyo_del_group - Delete "struct tomoyo_group".
413 * @element: Pointer to "struct list_head".
415 * Returns nothing.
417 static void tomoyo_del_group(struct list_head *element)
419 struct tomoyo_group *group =
420 container_of(element, typeof(*group), head.list);
421 tomoyo_put_name(group->group_name);
425 * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
427 * @element: Pointer to "struct list_head".
429 * Returns nothing.
431 static void tomoyo_del_number_group(struct list_head *element)
433 struct tomoyo_number_group *member =
434 container_of(element, typeof(*member), head.list);
438 * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
440 * @id: One of values in "enum tomoyo_policy_id".
441 * @member_list: Pointer to "struct list_head".
443 * Returns true if some elements are deleted, false otherwise.
445 static bool tomoyo_collect_member(const enum tomoyo_policy_id id,
446 struct list_head *member_list)
448 struct tomoyo_acl_head *member;
449 list_for_each_entry(member, member_list, list) {
450 if (!member->is_deleted)
451 continue;
452 if (!tomoyo_add_to_gc(id, &member->list))
453 return false;
455 return true;
459 * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
461 * @list: Pointer to "struct list_head".
463 * Returns true if some elements are deleted, false otherwise.
465 static bool tomoyo_collect_acl(struct list_head *list)
467 struct tomoyo_acl_info *acl;
468 list_for_each_entry(acl, list, list) {
469 if (!acl->is_deleted)
470 continue;
471 if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))
472 return false;
474 return true;
478 * tomoyo_collect_entry - Scan lists for deleted elements.
480 * Returns nothing.
482 static void tomoyo_collect_entry(void)
484 int i;
485 enum tomoyo_policy_id id;
486 struct tomoyo_policy_namespace *ns;
487 int idx;
488 if (mutex_lock_interruptible(&tomoyo_policy_lock))
489 return;
490 idx = tomoyo_read_lock();
492 struct tomoyo_domain_info *domain;
493 list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
494 if (!tomoyo_collect_acl(&domain->acl_info_list))
495 goto unlock;
496 if (!domain->is_deleted || atomic_read(&domain->users))
497 continue;
499 * Nobody is referring this domain. But somebody may
500 * refer this domain after successful execve().
501 * We recheck domain->users after SRCU synchronization.
503 if (!tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, &domain->list))
504 goto unlock;
507 list_for_each_entry_rcu(ns, &tomoyo_namespace_list, namespace_list) {
508 for (id = 0; id < TOMOYO_MAX_POLICY; id++)
509 if (!tomoyo_collect_member(id, &ns->policy_list[id]))
510 goto unlock;
511 for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
512 if (!tomoyo_collect_acl(&ns->acl_group[i]))
513 goto unlock;
514 for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
515 struct list_head *list = &ns->group_list[i];
516 struct tomoyo_group *group;
517 switch (i) {
518 case 0:
519 id = TOMOYO_ID_PATH_GROUP;
520 break;
521 default:
522 id = TOMOYO_ID_NUMBER_GROUP;
523 break;
525 list_for_each_entry(group, list, head.list) {
526 if (!tomoyo_collect_member
527 (id, &group->member_list))
528 goto unlock;
529 if (!list_empty(&group->member_list) ||
530 atomic_read(&group->head.users))
531 continue;
532 if (!tomoyo_add_to_gc(TOMOYO_ID_GROUP,
533 &group->head.list))
534 goto unlock;
538 id = TOMOYO_ID_CONDITION;
539 for (i = 0; i < TOMOYO_MAX_HASH + 1; i++) {
540 struct list_head *list = !i ?
541 &tomoyo_condition_list : &tomoyo_name_list[i - 1];
542 struct tomoyo_shared_acl_head *ptr;
543 list_for_each_entry(ptr, list, list) {
544 if (atomic_read(&ptr->users))
545 continue;
546 if (!tomoyo_add_to_gc(id, &ptr->list))
547 goto unlock;
549 id = TOMOYO_ID_NAME;
551 unlock:
552 tomoyo_read_unlock(idx);
553 mutex_unlock(&tomoyo_policy_lock);
557 * tomoyo_kfree_entry - Delete entries in tomoyo_gc_list.
559 * Returns true if some entries were kfree()d, false otherwise.
561 static bool tomoyo_kfree_entry(void)
563 struct tomoyo_gc *p;
564 struct tomoyo_gc *tmp;
565 bool result = false;
567 list_for_each_entry_safe(p, tmp, &tomoyo_gc_list, list) {
568 struct list_head *element = p->element;
571 * list_del_rcu() in tomoyo_add_to_gc() guarantees that the
572 * list element became no longer reachable from the list which
573 * the element was originally on (e.g. tomoyo_domain_list).
574 * Also, synchronize_srcu() in tomoyo_gc_thread() guarantees
575 * that the list element became no longer referenced by syscall
576 * users.
578 * However, there are three users which may still be using the
579 * list element. We need to defer until all of these users
580 * forget the list element.
582 * Firstly, defer until "struct tomoyo_io_buffer"->r.{domain,
583 * group,acl} and "struct tomoyo_io_buffer"->w.domain forget
584 * the list element.
586 if (tomoyo_struct_used_by_io_buffer(element))
587 continue;
589 * Secondly, defer until all other elements in the
590 * tomoyo_gc_list list forget the list element.
592 if (tomoyo_element_linked_by_gc((const u8 *) element, p->size))
593 continue;
594 switch (p->type) {
595 case TOMOYO_ID_TRANSITION_CONTROL:
596 tomoyo_del_transition_control(element);
597 break;
598 case TOMOYO_ID_AGGREGATOR:
599 tomoyo_del_aggregator(element);
600 break;
601 case TOMOYO_ID_MANAGER:
602 tomoyo_del_manager(element);
603 break;
604 case TOMOYO_ID_CONDITION:
605 tomoyo_del_condition(element);
606 break;
607 case TOMOYO_ID_NAME:
609 * Thirdly, defer until all "struct tomoyo_io_buffer"
610 * ->r.w[] forget the list element.
612 if (tomoyo_name_used_by_io_buffer(
613 container_of(element, typeof(struct tomoyo_name),
614 head.list)->entry.name, p->size))
615 continue;
616 tomoyo_del_name(element);
617 break;
618 case TOMOYO_ID_ACL:
619 tomoyo_del_acl(element);
620 break;
621 case TOMOYO_ID_DOMAIN:
622 if (!tomoyo_del_domain(element))
623 continue;
624 break;
625 case TOMOYO_ID_PATH_GROUP:
626 tomoyo_del_path_group(element);
627 break;
628 case TOMOYO_ID_GROUP:
629 tomoyo_del_group(element);
630 break;
631 case TOMOYO_ID_NUMBER_GROUP:
632 tomoyo_del_number_group(element);
633 break;
634 case TOMOYO_MAX_POLICY:
635 break;
637 tomoyo_memory_free(element);
638 list_del(&p->list);
639 kfree(p);
640 tomoyo_gc_list_len--;
641 result = true;
643 return result;
647 * tomoyo_gc_thread - Garbage collector thread function.
649 * @unused: Unused.
651 * In case OOM-killer choose this thread for termination, we create this thread
652 * as a short live thread whenever /sys/kernel/security/tomoyo/ interface was
653 * close()d.
655 * Returns 0.
657 static int tomoyo_gc_thread(void *unused)
659 /* Garbage collector thread is exclusive. */
660 static DEFINE_MUTEX(tomoyo_gc_mutex);
661 if (!mutex_trylock(&tomoyo_gc_mutex))
662 goto out;
663 daemonize("GC for TOMOYO");
664 do {
665 tomoyo_collect_entry();
666 if (list_empty(&tomoyo_gc_list))
667 break;
668 synchronize_srcu(&tomoyo_ss);
669 } while (tomoyo_kfree_entry());
671 struct tomoyo_io_buffer *head;
672 struct tomoyo_io_buffer *tmp;
674 spin_lock(&tomoyo_io_buffer_list_lock);
675 list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
676 list) {
677 if (head->users)
678 continue;
679 list_del(&head->list);
680 kfree(head->read_buf);
681 kfree(head->write_buf);
682 kfree(head);
684 spin_unlock(&tomoyo_io_buffer_list_lock);
686 mutex_unlock(&tomoyo_gc_mutex);
687 out:
688 /* This acts as do_exit(0). */
689 return 0;
693 * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
695 * @head: Pointer to "struct tomoyo_io_buffer".
696 * @is_register: True if register, false if unregister.
698 * Returns nothing.
700 void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
702 bool is_write = false;
704 spin_lock(&tomoyo_io_buffer_list_lock);
705 if (is_register) {
706 head->users = 1;
707 list_add(&head->list, &tomoyo_io_buffer_list);
708 } else {
709 is_write = head->write_buf != NULL;
710 if (!--head->users) {
711 list_del(&head->list);
712 kfree(head->read_buf);
713 kfree(head->write_buf);
714 kfree(head);
717 spin_unlock(&tomoyo_io_buffer_list_lock);
718 if (is_write) {
719 struct task_struct *task = kthread_create(tomoyo_gc_thread,
720 NULL,
721 "GC for TOMOYO");
722 if (!IS_ERR(task))
723 wake_up_process(task);