1// SPDX-License-Identifier: GPL-2.0
2/*
3 * security/tomoyo/gc.c
4 *
5 * Copyright (C) 2005-2011  NTT DATA CORPORATION
6 */
7
8#include "common.h"
9#include <linux/kthread.h>
10#include <linux/slab.h>
11
12/**
13 * tomoyo_memory_free - Free memory for elements.
14 *
15 * @ptr:  Pointer to allocated memory.
16 *
17 * Returns nothing.
18 *
19 * Caller holds tomoyo_policy_lock mutex.
20 */
21static inline void tomoyo_memory_free(void *ptr)
22{
23	tomoyo_memory_used[TOMOYO_MEMORY_POLICY] -= ksize(ptr);
24	kfree(ptr);
25}
26
27/* The list for "struct tomoyo_io_buffer". */
28static LIST_HEAD(tomoyo_io_buffer_list);
29/* Lock for protecting tomoyo_io_buffer_list. */
30static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);
31
32/**
33 * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
34 *
35 * @element: Pointer to "struct list_head".
36 *
37 * Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
38 * false otherwise.
39 */
40static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
41{
42	struct tomoyo_io_buffer *head;
43	bool in_use = false;
44
45	spin_lock(&tomoyo_io_buffer_list_lock);
46	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
47		head->users++;
48		spin_unlock(&tomoyo_io_buffer_list_lock);
49		mutex_lock(&head->io_sem);
50		if (head->r.domain == element || head->r.group == element ||
51		    head->r.acl == element || &head->w.domain->list == element)
52			in_use = true;
53		mutex_unlock(&head->io_sem);
54		spin_lock(&tomoyo_io_buffer_list_lock);
55		head->users--;
56		if (in_use)
57			break;
58	}
59	spin_unlock(&tomoyo_io_buffer_list_lock);
60	return in_use;
61}
62
63/**
64 * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.
65 *
66 * @string: String to check.
67 *
68 * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,
69 * false otherwise.
70 */
71static bool tomoyo_name_used_by_io_buffer(const char *string)
72{
73	struct tomoyo_io_buffer *head;
74	const size_t size = strlen(string) + 1;
75	bool in_use = false;
76
77	spin_lock(&tomoyo_io_buffer_list_lock);
78	list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
79		int i;
80
81		head->users++;
82		spin_unlock(&tomoyo_io_buffer_list_lock);
83		mutex_lock(&head->io_sem);
84		for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {
85			const char *w = head->r.w[i];
86
87			if (w < string || w > string + size)
88				continue;
89			in_use = true;
90			break;
91		}
92		mutex_unlock(&head->io_sem);
93		spin_lock(&tomoyo_io_buffer_list_lock);
94		head->users--;
95		if (in_use)
96			break;
97	}
98	spin_unlock(&tomoyo_io_buffer_list_lock);
99	return in_use;
100}
101
102/**
103 * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
104 *
105 * @element: Pointer to "struct list_head".
106 *
107 * Returns nothing.
108 */
109static inline void tomoyo_del_transition_control(struct list_head *element)
110{
111	struct tomoyo_transition_control *ptr =
112		container_of(element, typeof(*ptr), head.list);
113
114	tomoyo_put_name(ptr->domainname);
115	tomoyo_put_name(ptr->program);
116}
117
118/**
119 * tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
120 *
121 * @element: Pointer to "struct list_head".
122 *
123 * Returns nothing.
124 */
125static inline void tomoyo_del_aggregator(struct list_head *element)
126{
127	struct tomoyo_aggregator *ptr =
128		container_of(element, typeof(*ptr), head.list);
129
130	tomoyo_put_name(ptr->original_name);
131	tomoyo_put_name(ptr->aggregated_name);
132}
133
134/**
135 * tomoyo_del_manager - Delete members in "struct tomoyo_manager".
136 *
137 * @element: Pointer to "struct list_head".
138 *
139 * Returns nothing.
140 */
141static inline void tomoyo_del_manager(struct list_head *element)
142{
143	struct tomoyo_manager *ptr =
144		container_of(element, typeof(*ptr), head.list);
145
146	tomoyo_put_name(ptr->manager);
147}
148
149/**
150 * tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
151 *
152 * @element: Pointer to "struct list_head".
153 *
154 * Returns nothing.
155 */
156static void tomoyo_del_acl(struct list_head *element)
157{
158	struct tomoyo_acl_info *acl =
159		container_of(element, typeof(*acl), list);
160
161	tomoyo_put_condition(acl->cond);
162	switch (acl->type) {
163	case TOMOYO_TYPE_PATH_ACL:
164		{
165			struct tomoyo_path_acl *entry
166				= container_of(acl, typeof(*entry), head);
167			tomoyo_put_name_union(&entry->name);
168		}
169		break;
170	case TOMOYO_TYPE_PATH2_ACL:
171		{
172			struct tomoyo_path2_acl *entry
173				= container_of(acl, typeof(*entry), head);
174			tomoyo_put_name_union(&entry->name1);
175			tomoyo_put_name_union(&entry->name2);
176		}
177		break;
178	case TOMOYO_TYPE_PATH_NUMBER_ACL:
179		{
180			struct tomoyo_path_number_acl *entry
181				= container_of(acl, typeof(*entry), head);
182			tomoyo_put_name_union(&entry->name);
183			tomoyo_put_number_union(&entry->number);
184		}
185		break;
186	case TOMOYO_TYPE_MKDEV_ACL:
187		{
188			struct tomoyo_mkdev_acl *entry
189				= container_of(acl, typeof(*entry), head);
190			tomoyo_put_name_union(&entry->name);
191			tomoyo_put_number_union(&entry->mode);
192			tomoyo_put_number_union(&entry->major);
193			tomoyo_put_number_union(&entry->minor);
194		}
195		break;
196	case TOMOYO_TYPE_MOUNT_ACL:
197		{
198			struct tomoyo_mount_acl *entry
199				= container_of(acl, typeof(*entry), head);
200			tomoyo_put_name_union(&entry->dev_name);
201			tomoyo_put_name_union(&entry->dir_name);
202			tomoyo_put_name_union(&entry->fs_type);
203			tomoyo_put_number_union(&entry->flags);
204		}
205		break;
206	case TOMOYO_TYPE_ENV_ACL:
207		{
208			struct tomoyo_env_acl *entry =
209				container_of(acl, typeof(*entry), head);
210
211			tomoyo_put_name(entry->env);
212		}
213		break;
214	case TOMOYO_TYPE_INET_ACL:
215		{
216			struct tomoyo_inet_acl *entry =
217				container_of(acl, typeof(*entry), head);
218
219			tomoyo_put_group(entry->address.group);
220			tomoyo_put_number_union(&entry->port);
221		}
222		break;
223	case TOMOYO_TYPE_UNIX_ACL:
224		{
225			struct tomoyo_unix_acl *entry =
226				container_of(acl, typeof(*entry), head);
227
228			tomoyo_put_name_union(&entry->name);
229		}
230		break;
231	case TOMOYO_TYPE_MANUAL_TASK_ACL:
232		{
233			struct tomoyo_task_acl *entry =
234				container_of(acl, typeof(*entry), head);
235
236			tomoyo_put_name(entry->domainname);
237		}
238		break;
239	}
240}
241
242/**
243 * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
244 *
245 * @element: Pointer to "struct list_head".
246 *
247 * Returns nothing.
248 *
249 * Caller holds tomoyo_policy_lock mutex.
250 */
251static inline void tomoyo_del_domain(struct list_head *element)
252{
253	struct tomoyo_domain_info *domain =
254		container_of(element, typeof(*domain), list);
255	struct tomoyo_acl_info *acl;
256	struct tomoyo_acl_info *tmp;
257
258	/*
259	 * Since this domain is referenced from neither
260	 * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
261	 * elements without checking for is_deleted flag.
262	 */
263	list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
264		tomoyo_del_acl(&acl->list);
265		tomoyo_memory_free(acl);
266	}
267	tomoyo_put_name(domain->domainname);
268}
269
270/**
271 * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
272 *
273 * @element: Pointer to "struct list_head".
274 *
275 * Returns nothing.
276 */
277void tomoyo_del_condition(struct list_head *element)
278{
279	struct tomoyo_condition *cond = container_of(element, typeof(*cond),
280						     head.list);
281	const u16 condc = cond->condc;
282	const u16 numbers_count = cond->numbers_count;
283	const u16 names_count = cond->names_count;
284	const u16 argc = cond->argc;
285	const u16 envc = cond->envc;
286	unsigned int i;
287	const struct tomoyo_condition_element *condp
288		= (const struct tomoyo_condition_element *) (cond + 1);
289	struct tomoyo_number_union *numbers_p
290		= (struct tomoyo_number_union *) (condp + condc);
291	struct tomoyo_name_union *names_p
292		= (struct tomoyo_name_union *) (numbers_p + numbers_count);
293	const struct tomoyo_argv *argv
294		= (const struct tomoyo_argv *) (names_p + names_count);
295	const struct tomoyo_envp *envp
296		= (const struct tomoyo_envp *) (argv + argc);
297
298	for (i = 0; i < numbers_count; i++)
299		tomoyo_put_number_union(numbers_p++);
300	for (i = 0; i < names_count; i++)
301		tomoyo_put_name_union(names_p++);
302	for (i = 0; i < argc; argv++, i++)
303		tomoyo_put_name(argv->value);
304	for (i = 0; i < envc; envp++, i++) {
305		tomoyo_put_name(envp->name);
306		tomoyo_put_name(envp->value);
307	}
308}
309
310/**
311 * tomoyo_del_name - Delete members in "struct tomoyo_name".
312 *
313 * @element: Pointer to "struct list_head".
314 *
315 * Returns nothing.
316 */
317static inline void tomoyo_del_name(struct list_head *element)
318{
319	/* Nothing to do. */
320}
321
322/**
323 * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
324 *
325 * @element: Pointer to "struct list_head".
326 *
327 * Returns nothing.
328 */
329static inline void tomoyo_del_path_group(struct list_head *element)
330{
331	struct tomoyo_path_group *member =
332		container_of(element, typeof(*member), head.list);
333
334	tomoyo_put_name(member->member_name);
335}
336
337/**
338 * tomoyo_del_group - Delete "struct tomoyo_group".
339 *
340 * @element: Pointer to "struct list_head".
341 *
342 * Returns nothing.
343 */
344static inline void tomoyo_del_group(struct list_head *element)
345{
346	struct tomoyo_group *group =
347		container_of(element, typeof(*group), head.list);
348
349	tomoyo_put_name(group->group_name);
350}
351
352/**
353 * tomoyo_del_address_group - Delete members in "struct tomoyo_address_group".
354 *
355 * @element: Pointer to "struct list_head".
356 *
357 * Returns nothing.
358 */
359static inline void tomoyo_del_address_group(struct list_head *element)
360{
361	/* Nothing to do. */
362}
363
364/**
365 * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
366 *
367 * @element: Pointer to "struct list_head".
368 *
369 * Returns nothing.
370 */
371static inline void tomoyo_del_number_group(struct list_head *element)
372{
373	/* Nothing to do. */
374}
375
376/**
377 * tomoyo_try_to_gc - Try to kfree() an entry.
378 *
379 * @type:    One of values in "enum tomoyo_policy_id".
380 * @element: Pointer to "struct list_head".
381 *
382 * Returns nothing.
383 *
384 * Caller holds tomoyo_policy_lock mutex.
385 */
386static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
387			     struct list_head *element)
388{
389	/*
390	 * __list_del_entry() guarantees that the list element became no longer
391	 * reachable from the list which the element was originally on (e.g.
392	 * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
393	 * list element became no longer referenced by syscall users.
394	 */
395	__list_del_entry(element);
396	mutex_unlock(&tomoyo_policy_lock);
397	synchronize_srcu(&tomoyo_ss);
398	/*
399	 * However, there are two users which may still be using the list
400	 * element. We need to defer until both users forget this element.
401	 *
402	 * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}
403	 * and "struct tomoyo_io_buffer"->w.domain forget this element.
404	 */
405	if (tomoyo_struct_used_by_io_buffer(element))
406		goto reinject;
407	switch (type) {
408	case TOMOYO_ID_TRANSITION_CONTROL:
409		tomoyo_del_transition_control(element);
410		break;
411	case TOMOYO_ID_MANAGER:
412		tomoyo_del_manager(element);
413		break;
414	case TOMOYO_ID_AGGREGATOR:
415		tomoyo_del_aggregator(element);
416		break;
417	case TOMOYO_ID_GROUP:
418		tomoyo_del_group(element);
419		break;
420	case TOMOYO_ID_PATH_GROUP:
421		tomoyo_del_path_group(element);
422		break;
423	case TOMOYO_ID_ADDRESS_GROUP:
424		tomoyo_del_address_group(element);
425		break;
426	case TOMOYO_ID_NUMBER_GROUP:
427		tomoyo_del_number_group(element);
428		break;
429	case TOMOYO_ID_CONDITION:
430		tomoyo_del_condition(element);
431		break;
432	case TOMOYO_ID_NAME:
433		/*
434		 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]
435		 * forget this element.
436		 */
437		if (tomoyo_name_used_by_io_buffer
438		    (container_of(element, typeof(struct tomoyo_name),
439				  head.list)->entry.name))
440			goto reinject;
441		tomoyo_del_name(element);
442		break;
443	case TOMOYO_ID_ACL:
444		tomoyo_del_acl(element);
445		break;
446	case TOMOYO_ID_DOMAIN:
447		/*
448		 * Don't kfree() until all "struct cred"->security forget this
449		 * element.
450		 */
451		if (atomic_read(&container_of
452				(element, typeof(struct tomoyo_domain_info),
453				 list)->users))
454			goto reinject;
455		break;
456	case TOMOYO_MAX_POLICY:
457		break;
458	}
459	mutex_lock(&tomoyo_policy_lock);
460	if (type == TOMOYO_ID_DOMAIN)
461		tomoyo_del_domain(element);
462	tomoyo_memory_free(element);
463	return;
464reinject:
465	/*
466	 * We can safely reinject this element here because
467	 * (1) Appending list elements and removing list elements are protected
468	 *     by tomoyo_policy_lock mutex.
469	 * (2) Only this function removes list elements and this function is
470	 *     exclusively executed by tomoyo_gc_mutex mutex.
471	 * are true.
472	 */
473	mutex_lock(&tomoyo_policy_lock);
474	list_add_rcu(element, element->prev);
475}
476
477/**
478 * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
479 *
480 * @id:          One of values in "enum tomoyo_policy_id".
481 * @member_list: Pointer to "struct list_head".
482 *
483 * Returns nothing.
484 */
485static void tomoyo_collect_member(const enum tomoyo_policy_id id,
486				  struct list_head *member_list)
487{
488	struct tomoyo_acl_head *member;
489	struct tomoyo_acl_head *tmp;
490
491	list_for_each_entry_safe(member, tmp, member_list, list) {
492		if (!member->is_deleted)
493			continue;
494		member->is_deleted = TOMOYO_GC_IN_PROGRESS;
495		tomoyo_try_to_gc(id, &member->list);
496	}
497}
498
499/**
500 * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
501 *
502 * @list: Pointer to "struct list_head".
503 *
504 * Returns nothing.
505 */
506static void tomoyo_collect_acl(struct list_head *list)
507{
508	struct tomoyo_acl_info *acl;
509	struct tomoyo_acl_info *tmp;
510
511	list_for_each_entry_safe(acl, tmp, list, list) {
512		if (!acl->is_deleted)
513			continue;
514		acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
515		tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
516	}
517}
518
519/**
520 * tomoyo_collect_entry - Try to kfree() deleted elements.
521 *
522 * Returns nothing.
523 */
524static void tomoyo_collect_entry(void)
525{
526	int i;
527	enum tomoyo_policy_id id;
528	struct tomoyo_policy_namespace *ns;
529
530	mutex_lock(&tomoyo_policy_lock);
531	{
532		struct tomoyo_domain_info *domain;
533		struct tomoyo_domain_info *tmp;
534
535		list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,
536					 list) {
537			tomoyo_collect_acl(&domain->acl_info_list);
538			if (!domain->is_deleted || atomic_read(&domain->users))
539				continue;
540			tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
541		}
542	}
543	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
544		for (id = 0; id < TOMOYO_MAX_POLICY; id++)
545			tomoyo_collect_member(id, &ns->policy_list[id]);
546		for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
547			tomoyo_collect_acl(&ns->acl_group[i]);
548	}
549	{
550		struct tomoyo_shared_acl_head *ptr;
551		struct tomoyo_shared_acl_head *tmp;
552
553		list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,
554					 list) {
555			if (atomic_read(&ptr->users) > 0)
556				continue;
557			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
558			tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);
559		}
560	}
561	list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
562		for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
563			struct list_head *list = &ns->group_list[i];
564			struct tomoyo_group *group;
565			struct tomoyo_group *tmp;
566
567			switch (i) {
568			case 0:
569				id = TOMOYO_ID_PATH_GROUP;
570				break;
571			case 1:
572				id = TOMOYO_ID_NUMBER_GROUP;
573				break;
574			default:
575				id = TOMOYO_ID_ADDRESS_GROUP;
576				break;
577			}
578			list_for_each_entry_safe(group, tmp, list, head.list) {
579				tomoyo_collect_member(id, &group->member_list);
580				if (!list_empty(&group->member_list) ||
581				    atomic_read(&group->head.users) > 0)
582					continue;
583				atomic_set(&group->head.users,
584					   TOMOYO_GC_IN_PROGRESS);
585				tomoyo_try_to_gc(TOMOYO_ID_GROUP,
586						 &group->head.list);
587			}
588		}
589	}
590	for (i = 0; i < TOMOYO_MAX_HASH; i++) {
591		struct list_head *list = &tomoyo_name_list[i];
592		struct tomoyo_shared_acl_head *ptr;
593		struct tomoyo_shared_acl_head *tmp;
594
595		list_for_each_entry_safe(ptr, tmp, list, list) {
596			if (atomic_read(&ptr->users) > 0)
597				continue;
598			atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
599			tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
600		}
601	}
602	mutex_unlock(&tomoyo_policy_lock);
603}
604
605/**
606 * tomoyo_gc_thread - Garbage collector thread function.
607 *
608 * @unused: Unused.
609 *
610 * Returns 0.
611 */
612static int tomoyo_gc_thread(void *unused)
613{
614	/* Garbage collector thread is exclusive. */
615	static DEFINE_MUTEX(tomoyo_gc_mutex);
616
617	if (!mutex_trylock(&tomoyo_gc_mutex))
618		goto out;
619	tomoyo_collect_entry();
620	{
621		struct tomoyo_io_buffer *head;
622		struct tomoyo_io_buffer *tmp;
623
624		spin_lock(&tomoyo_io_buffer_list_lock);
625		list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
626					 list) {
627			if (head->users)
628				continue;
629			list_del(&head->list);
630			kfree(head->read_buf);
631			kfree(head->write_buf);
632			kfree(head);
633		}
634		spin_unlock(&tomoyo_io_buffer_list_lock);
635	}
636	mutex_unlock(&tomoyo_gc_mutex);
637out:
638	/* This acts as do_exit(0). */
639	return 0;
640}
641
642/**
643 * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
644 *
645 * @head:        Pointer to "struct tomoyo_io_buffer".
646 * @is_register: True if register, false if unregister.
647 *
648 * Returns nothing.
649 */
650void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
651{
652	bool is_write = false;
653
654	spin_lock(&tomoyo_io_buffer_list_lock);
655	if (is_register) {
656		head->users = 1;
657		list_add(&head->list, &tomoyo_io_buffer_list);
658	} else {
659		is_write = head->write_buf != NULL;
660		if (!--head->users) {
661			list_del(&head->list);
662			kfree(head->read_buf);
663			kfree(head->write_buf);
664			kfree(head);
665		}
666	}
667	spin_unlock(&tomoyo_io_buffer_list_lock);
668	if (is_write)
669		kthread_run(tomoyo_gc_thread, NULL, "GC for TOMOYO");
670}
671