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TOMOYO Linux Cross Reference
Linux/security/tomoyo/gc.c

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  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  */
 21 static 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". */
 28 static LIST_HEAD(tomoyo_io_buffer_list);
 29 /* Lock for protecting tomoyo_io_buffer_list. */
 30 static 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  */
 40 static 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  */
 71 static 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  */
109 static 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  */
125 static 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  */
141 static 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  */
156 static 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  */
251 static 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  */
277 void 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  */
317 static 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  */
329 static 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  */
344 static 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  */
359 static 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  */
371 static 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  */
386 static 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;
464 reinject:
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  */
485 static 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  */
506 static 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  */
524 static 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  */
612 static 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);
637 out:
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  */
650 void 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 

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