security/tomoyo/gc.c

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