linux/security/tomoyo/gc.c
<<
>>
Prefs
   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/**
  12 * tomoyo_memory_free - Free memory for elements.
  13 *
  14 * @ptr:  Pointer to allocated memory.
  15 *
  16 * Returns nothing.
  17 *
  18 * Caller holds tomoyo_policy_lock mutex.
  19 */
  20static inline void tomoyo_memory_free(void *ptr)
  21{
  22        tomoyo_memory_used[TOMOYO_MEMORY_POLICY] -= ksize(ptr);
  23        kfree(ptr);
  24}
  25
  26/* The list for "struct tomoyo_io_buffer". */
  27static LIST_HEAD(tomoyo_io_buffer_list);
  28/* Lock for protecting tomoyo_io_buffer_list. */
  29static DEFINE_SPINLOCK(tomoyo_io_buffer_list_lock);
  30
  31/**
  32 * tomoyo_struct_used_by_io_buffer - Check whether the list element is used by /sys/kernel/security/tomoyo/ users or not.
  33 *
  34 * @element: Pointer to "struct list_head".
  35 *
  36 * Returns true if @element is used by /sys/kernel/security/tomoyo/ users,
  37 * false otherwise.
  38 */
  39static bool tomoyo_struct_used_by_io_buffer(const struct list_head *element)
  40{
  41        struct tomoyo_io_buffer *head;
  42        bool in_use = false;
  43
  44        spin_lock(&tomoyo_io_buffer_list_lock);
  45        list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
  46                head->users++;
  47                spin_unlock(&tomoyo_io_buffer_list_lock);
  48                mutex_lock(&head->io_sem);
  49                if (head->r.domain == element || head->r.group == element ||
  50                    head->r.acl == element || &head->w.domain->list == element)
  51                        in_use = true;
  52                mutex_unlock(&head->io_sem);
  53                spin_lock(&tomoyo_io_buffer_list_lock);
  54                head->users--;
  55                if (in_use)
  56                        break;
  57        }
  58        spin_unlock(&tomoyo_io_buffer_list_lock);
  59        return in_use;
  60}
  61
  62/**
  63 * tomoyo_name_used_by_io_buffer - Check whether the string is used by /sys/kernel/security/tomoyo/ users or not.
  64 *
  65 * @string: String to check.
  66 *
  67 * Returns true if @string is used by /sys/kernel/security/tomoyo/ users,
  68 * false otherwise.
  69 */
  70static bool tomoyo_name_used_by_io_buffer(const char *string)
  71{
  72        struct tomoyo_io_buffer *head;
  73        const size_t size = strlen(string) + 1;
  74        bool in_use = false;
  75
  76        spin_lock(&tomoyo_io_buffer_list_lock);
  77        list_for_each_entry(head, &tomoyo_io_buffer_list, list) {
  78                int i;
  79                head->users++;
  80                spin_unlock(&tomoyo_io_buffer_list_lock);
  81                mutex_lock(&head->io_sem);
  82                for (i = 0; i < TOMOYO_MAX_IO_READ_QUEUE; i++) {
  83                        const char *w = head->r.w[i];
  84                        if (w < string || w > string + size)
  85                                continue;
  86                        in_use = true;
  87                        break;
  88                }
  89                mutex_unlock(&head->io_sem);
  90                spin_lock(&tomoyo_io_buffer_list_lock);
  91                head->users--;
  92                if (in_use)
  93                        break;
  94        }
  95        spin_unlock(&tomoyo_io_buffer_list_lock);
  96        return in_use;
  97}
  98
  99/**
 100 * tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
 101 *
 102 * @element: Pointer to "struct list_head".
 103 *
 104 * Returns nothing.
 105 */
 106static inline void tomoyo_del_transition_control(struct list_head *element)
 107{
 108        struct tomoyo_transition_control *ptr =
 109                container_of(element, typeof(*ptr), head.list);
 110        tomoyo_put_name(ptr->domainname);
 111        tomoyo_put_name(ptr->program);
 112}
 113
 114/**
 115 * tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
 116 *
 117 * @element: Pointer to "struct list_head".
 118 *
 119 * Returns nothing.
 120 */
 121static inline void tomoyo_del_aggregator(struct list_head *element)
 122{
 123        struct tomoyo_aggregator *ptr =
 124                container_of(element, typeof(*ptr), head.list);
 125        tomoyo_put_name(ptr->original_name);
 126        tomoyo_put_name(ptr->aggregated_name);
 127}
 128
 129/**
 130 * tomoyo_del_manager - Delete members in "struct tomoyo_manager".
 131 *
 132 * @element: Pointer to "struct list_head".
 133 *
 134 * Returns nothing.
 135 */
 136static inline void tomoyo_del_manager(struct list_head *element)
 137{
 138        struct tomoyo_manager *ptr =
 139                container_of(element, typeof(*ptr), head.list);
 140        tomoyo_put_name(ptr->manager);
 141}
 142
 143/**
 144 * tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
 145 *
 146 * @element: Pointer to "struct list_head".
 147 *
 148 * Returns nothing.
 149 */
 150static void tomoyo_del_acl(struct list_head *element)
 151{
 152        struct tomoyo_acl_info *acl =
 153                container_of(element, typeof(*acl), list);
 154        tomoyo_put_condition(acl->cond);
 155        switch (acl->type) {
 156        case TOMOYO_TYPE_PATH_ACL:
 157                {
 158                        struct tomoyo_path_acl *entry
 159                                = container_of(acl, typeof(*entry), head);
 160                        tomoyo_put_name_union(&entry->name);
 161                }
 162                break;
 163        case TOMOYO_TYPE_PATH2_ACL:
 164                {
 165                        struct tomoyo_path2_acl *entry
 166                                = container_of(acl, typeof(*entry), head);
 167                        tomoyo_put_name_union(&entry->name1);
 168                        tomoyo_put_name_union(&entry->name2);
 169                }
 170                break;
 171        case TOMOYO_TYPE_PATH_NUMBER_ACL:
 172                {
 173                        struct tomoyo_path_number_acl *entry
 174                                = container_of(acl, typeof(*entry), head);
 175                        tomoyo_put_name_union(&entry->name);
 176                        tomoyo_put_number_union(&entry->number);
 177                }
 178                break;
 179        case TOMOYO_TYPE_MKDEV_ACL:
 180                {
 181                        struct tomoyo_mkdev_acl *entry
 182                                = container_of(acl, typeof(*entry), head);
 183                        tomoyo_put_name_union(&entry->name);
 184                        tomoyo_put_number_union(&entry->mode);
 185                        tomoyo_put_number_union(&entry->major);
 186                        tomoyo_put_number_union(&entry->minor);
 187                }
 188                break;
 189        case TOMOYO_TYPE_MOUNT_ACL:
 190                {
 191                        struct tomoyo_mount_acl *entry
 192                                = container_of(acl, typeof(*entry), head);
 193                        tomoyo_put_name_union(&entry->dev_name);
 194                        tomoyo_put_name_union(&entry->dir_name);
 195                        tomoyo_put_name_union(&entry->fs_type);
 196                        tomoyo_put_number_union(&entry->flags);
 197                }
 198                break;
 199        case TOMOYO_TYPE_ENV_ACL:
 200                {
 201                        struct tomoyo_env_acl *entry =
 202                                container_of(acl, typeof(*entry), head);
 203
 204                        tomoyo_put_name(entry->env);
 205                }
 206                break;
 207        case TOMOYO_TYPE_INET_ACL:
 208                {
 209                        struct tomoyo_inet_acl *entry =
 210                                container_of(acl, typeof(*entry), head);
 211
 212                        tomoyo_put_group(entry->address.group);
 213                        tomoyo_put_number_union(&entry->port);
 214                }
 215                break;
 216        case TOMOYO_TYPE_UNIX_ACL:
 217                {
 218                        struct tomoyo_unix_acl *entry =
 219                                container_of(acl, typeof(*entry), head);
 220
 221                        tomoyo_put_name_union(&entry->name);
 222                }
 223                break;
 224        case TOMOYO_TYPE_MANUAL_TASK_ACL:
 225                {
 226                        struct tomoyo_task_acl *entry =
 227                                container_of(acl, typeof(*entry), head);
 228                        tomoyo_put_name(entry->domainname);
 229                }
 230                break;
 231        }
 232}
 233
 234/**
 235 * tomoyo_del_domain - Delete members in "struct tomoyo_domain_info".
 236 *
 237 * @element: Pointer to "struct list_head".
 238 *
 239 * Returns nothing.
 240 *
 241 * Caller holds tomoyo_policy_lock mutex.
 242 */
 243static inline void tomoyo_del_domain(struct list_head *element)
 244{
 245        struct tomoyo_domain_info *domain =
 246                container_of(element, typeof(*domain), list);
 247        struct tomoyo_acl_info *acl;
 248        struct tomoyo_acl_info *tmp;
 249        /*
 250         * Since this domain is referenced from neither
 251         * "struct tomoyo_io_buffer" nor "struct cred"->security, we can delete
 252         * elements without checking for is_deleted flag.
 253         */
 254        list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
 255                tomoyo_del_acl(&acl->list);
 256                tomoyo_memory_free(acl);
 257        }
 258        tomoyo_put_name(domain->domainname);
 259}
 260
 261/**
 262 * tomoyo_del_condition - Delete members in "struct tomoyo_condition".
 263 *
 264 * @element: Pointer to "struct list_head".
 265 *
 266 * Returns nothing.
 267 */
 268void tomoyo_del_condition(struct list_head *element)
 269{
 270        struct tomoyo_condition *cond = container_of(element, typeof(*cond),
 271                                                     head.list);
 272        const u16 condc = cond->condc;
 273        const u16 numbers_count = cond->numbers_count;
 274        const u16 names_count = cond->names_count;
 275        const u16 argc = cond->argc;
 276        const u16 envc = cond->envc;
 277        unsigned int i;
 278        const struct tomoyo_condition_element *condp
 279                = (const struct tomoyo_condition_element *) (cond + 1);
 280        struct tomoyo_number_union *numbers_p
 281                = (struct tomoyo_number_union *) (condp + condc);
 282        struct tomoyo_name_union *names_p
 283                = (struct tomoyo_name_union *) (numbers_p + numbers_count);
 284        const struct tomoyo_argv *argv
 285                = (const struct tomoyo_argv *) (names_p + names_count);
 286        const struct tomoyo_envp *envp
 287                = (const struct tomoyo_envp *) (argv + argc);
 288        for (i = 0; i < numbers_count; i++)
 289                tomoyo_put_number_union(numbers_p++);
 290        for (i = 0; i < names_count; i++)
 291                tomoyo_put_name_union(names_p++);
 292        for (i = 0; i < argc; argv++, i++)
 293                tomoyo_put_name(argv->value);
 294        for (i = 0; i < envc; envp++, i++) {
 295                tomoyo_put_name(envp->name);
 296                tomoyo_put_name(envp->value);
 297        }
 298}
 299
 300/**
 301 * tomoyo_del_name - Delete members in "struct tomoyo_name".
 302 *
 303 * @element: Pointer to "struct list_head".
 304 *
 305 * Returns nothing.
 306 */
 307static inline void tomoyo_del_name(struct list_head *element)
 308{
 309        /* Nothing to do. */
 310}
 311
 312/**
 313 * tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
 314 *
 315 * @element: Pointer to "struct list_head".
 316 *
 317 * Returns nothing.
 318 */
 319static inline void tomoyo_del_path_group(struct list_head *element)
 320{
 321        struct tomoyo_path_group *member =
 322                container_of(element, typeof(*member), head.list);
 323        tomoyo_put_name(member->member_name);
 324}
 325
 326/**
 327 * tomoyo_del_group - Delete "struct tomoyo_group".
 328 *
 329 * @element: Pointer to "struct list_head".
 330 *
 331 * Returns nothing.
 332 */
 333static inline void tomoyo_del_group(struct list_head *element)
 334{
 335        struct tomoyo_group *group =
 336                container_of(element, typeof(*group), head.list);
 337        tomoyo_put_name(group->group_name);
 338}
 339
 340/**
 341 * tomoyo_del_address_group - Delete members in "struct tomoyo_address_group".
 342 *
 343 * @element: Pointer to "struct list_head".
 344 *
 345 * Returns nothing.
 346 */
 347static inline void tomoyo_del_address_group(struct list_head *element)
 348{
 349        /* Nothing to do. */
 350}
 351
 352/**
 353 * tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
 354 *
 355 * @element: Pointer to "struct list_head".
 356 *
 357 * Returns nothing.
 358 */
 359static inline void tomoyo_del_number_group(struct list_head *element)
 360{
 361        /* Nothing to do. */
 362}
 363
 364/**
 365 * tomoyo_try_to_gc - Try to kfree() an entry.
 366 *
 367 * @type:    One of values in "enum tomoyo_policy_id".
 368 * @element: Pointer to "struct list_head".
 369 *
 370 * Returns nothing.
 371 *
 372 * Caller holds tomoyo_policy_lock mutex.
 373 */
 374static void tomoyo_try_to_gc(const enum tomoyo_policy_id type,
 375                             struct list_head *element)
 376{
 377        /*
 378         * __list_del_entry() guarantees that the list element became no longer
 379         * reachable from the list which the element was originally on (e.g.
 380         * tomoyo_domain_list). Also, synchronize_srcu() guarantees that the
 381         * list element became no longer referenced by syscall users.
 382         */
 383        __list_del_entry(element);
 384        mutex_unlock(&tomoyo_policy_lock);
 385        synchronize_srcu(&tomoyo_ss);
 386        /*
 387         * However, there are two users which may still be using the list
 388         * element. We need to defer until both users forget this element.
 389         *
 390         * Don't kfree() until "struct tomoyo_io_buffer"->r.{domain,group,acl}
 391         * and "struct tomoyo_io_buffer"->w.domain forget this element.
 392         */
 393        if (tomoyo_struct_used_by_io_buffer(element))
 394                goto reinject;
 395        switch (type) {
 396        case TOMOYO_ID_TRANSITION_CONTROL:
 397                tomoyo_del_transition_control(element);
 398                break;
 399        case TOMOYO_ID_MANAGER:
 400                tomoyo_del_manager(element);
 401                break;
 402        case TOMOYO_ID_AGGREGATOR:
 403                tomoyo_del_aggregator(element);
 404                break;
 405        case TOMOYO_ID_GROUP:
 406                tomoyo_del_group(element);
 407                break;
 408        case TOMOYO_ID_PATH_GROUP:
 409                tomoyo_del_path_group(element);
 410                break;
 411        case TOMOYO_ID_ADDRESS_GROUP:
 412                tomoyo_del_address_group(element);
 413                break;
 414        case TOMOYO_ID_NUMBER_GROUP:
 415                tomoyo_del_number_group(element);
 416                break;
 417        case TOMOYO_ID_CONDITION:
 418                tomoyo_del_condition(element);
 419                break;
 420        case TOMOYO_ID_NAME:
 421                /*
 422                 * Don't kfree() until all "struct tomoyo_io_buffer"->r.w[]
 423                 * forget this element.
 424                 */
 425                if (tomoyo_name_used_by_io_buffer
 426                    (container_of(element, typeof(struct tomoyo_name),
 427                                  head.list)->entry.name))
 428                        goto reinject;
 429                tomoyo_del_name(element);
 430                break;
 431        case TOMOYO_ID_ACL:
 432                tomoyo_del_acl(element);
 433                break;
 434        case TOMOYO_ID_DOMAIN:
 435                /*
 436                 * Don't kfree() until all "struct cred"->security forget this
 437                 * element.
 438                 */
 439                if (atomic_read(&container_of
 440                                (element, typeof(struct tomoyo_domain_info),
 441                                 list)->users))
 442                        goto reinject;
 443                break;
 444        case TOMOYO_MAX_POLICY:
 445                break;
 446        }
 447        mutex_lock(&tomoyo_policy_lock);
 448        if (type == TOMOYO_ID_DOMAIN)
 449                tomoyo_del_domain(element);
 450        tomoyo_memory_free(element);
 451        return;
 452reinject:
 453        /*
 454         * We can safely reinject this element here bacause
 455         * (1) Appending list elements and removing list elements are protected
 456         *     by tomoyo_policy_lock mutex.
 457         * (2) Only this function removes list elements and this function is
 458         *     exclusively executed by tomoyo_gc_mutex mutex.
 459         * are true.
 460         */
 461        mutex_lock(&tomoyo_policy_lock);
 462        list_add_rcu(element, element->prev);
 463}
 464
 465/**
 466 * tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
 467 *
 468 * @id:          One of values in "enum tomoyo_policy_id".
 469 * @member_list: Pointer to "struct list_head".
 470 *
 471 * Returns nothing.
 472 */
 473static void tomoyo_collect_member(const enum tomoyo_policy_id id,
 474                                  struct list_head *member_list)
 475{
 476        struct tomoyo_acl_head *member;
 477        struct tomoyo_acl_head *tmp;
 478        list_for_each_entry_safe(member, tmp, member_list, list) {
 479                if (!member->is_deleted)
 480                        continue;
 481                member->is_deleted = TOMOYO_GC_IN_PROGRESS;
 482                tomoyo_try_to_gc(id, &member->list);
 483        }
 484}
 485
 486/**
 487 * tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
 488 *
 489 * @list: Pointer to "struct list_head".
 490 *
 491 * Returns nothing.
 492 */
 493static void tomoyo_collect_acl(struct list_head *list)
 494{
 495        struct tomoyo_acl_info *acl;
 496        struct tomoyo_acl_info *tmp;
 497        list_for_each_entry_safe(acl, tmp, list, list) {
 498                if (!acl->is_deleted)
 499                        continue;
 500                acl->is_deleted = TOMOYO_GC_IN_PROGRESS;
 501                tomoyo_try_to_gc(TOMOYO_ID_ACL, &acl->list);
 502        }
 503}
 504
 505/**
 506 * tomoyo_collect_entry - Try to kfree() deleted elements.
 507 *
 508 * Returns nothing.
 509 */
 510static void tomoyo_collect_entry(void)
 511{
 512        int i;
 513        enum tomoyo_policy_id id;
 514        struct tomoyo_policy_namespace *ns;
 515        mutex_lock(&tomoyo_policy_lock);
 516        {
 517                struct tomoyo_domain_info *domain;
 518                struct tomoyo_domain_info *tmp;
 519                list_for_each_entry_safe(domain, tmp, &tomoyo_domain_list,
 520                                         list) {
 521                        tomoyo_collect_acl(&domain->acl_info_list);
 522                        if (!domain->is_deleted || atomic_read(&domain->users))
 523                                continue;
 524                        tomoyo_try_to_gc(TOMOYO_ID_DOMAIN, &domain->list);
 525                }
 526        }
 527        list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
 528                for (id = 0; id < TOMOYO_MAX_POLICY; id++)
 529                        tomoyo_collect_member(id, &ns->policy_list[id]);
 530                for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
 531                        tomoyo_collect_acl(&ns->acl_group[i]);
 532        }
 533        {
 534                struct tomoyo_shared_acl_head *ptr;
 535                struct tomoyo_shared_acl_head *tmp;
 536                list_for_each_entry_safe(ptr, tmp, &tomoyo_condition_list,
 537                                         list) {
 538                        if (atomic_read(&ptr->users) > 0)
 539                                continue;
 540                        atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
 541                        tomoyo_try_to_gc(TOMOYO_ID_CONDITION, &ptr->list);
 542                }
 543        }
 544        list_for_each_entry(ns, &tomoyo_namespace_list, namespace_list) {
 545                for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
 546                        struct list_head *list = &ns->group_list[i];
 547                        struct tomoyo_group *group;
 548                        struct tomoyo_group *tmp;
 549                        switch (i) {
 550                        case 0:
 551                                id = TOMOYO_ID_PATH_GROUP;
 552                                break;
 553                        case 1:
 554                                id = TOMOYO_ID_NUMBER_GROUP;
 555                                break;
 556                        default:
 557                                id = TOMOYO_ID_ADDRESS_GROUP;
 558                                break;
 559                        }
 560                        list_for_each_entry_safe(group, tmp, list, head.list) {
 561                                tomoyo_collect_member(id, &group->member_list);
 562                                if (!list_empty(&group->member_list) ||
 563                                    atomic_read(&group->head.users) > 0)
 564                                        continue;
 565                                atomic_set(&group->head.users,
 566                                           TOMOYO_GC_IN_PROGRESS);
 567                                tomoyo_try_to_gc(TOMOYO_ID_GROUP,
 568                                                 &group->head.list);
 569                        }
 570                }
 571        }
 572        for (i = 0; i < TOMOYO_MAX_HASH; i++) {
 573                struct list_head *list = &tomoyo_name_list[i];
 574                struct tomoyo_shared_acl_head *ptr;
 575                struct tomoyo_shared_acl_head *tmp;
 576                list_for_each_entry_safe(ptr, tmp, list, list) {
 577                        if (atomic_read(&ptr->users) > 0)
 578                                continue;
 579                        atomic_set(&ptr->users, TOMOYO_GC_IN_PROGRESS);
 580                        tomoyo_try_to_gc(TOMOYO_ID_NAME, &ptr->list);
 581                }
 582        }
 583        mutex_unlock(&tomoyo_policy_lock);
 584}
 585
 586/**
 587 * tomoyo_gc_thread - Garbage collector thread function.
 588 *
 589 * @unused: Unused.
 590 *
 591 * Returns 0.
 592 */
 593static int tomoyo_gc_thread(void *unused)
 594{
 595        /* Garbage collector thread is exclusive. */
 596        static DEFINE_MUTEX(tomoyo_gc_mutex);
 597        if (!mutex_trylock(&tomoyo_gc_mutex))
 598                goto out;
 599        tomoyo_collect_entry();
 600        {
 601                struct tomoyo_io_buffer *head;
 602                struct tomoyo_io_buffer *tmp;
 603
 604                spin_lock(&tomoyo_io_buffer_list_lock);
 605                list_for_each_entry_safe(head, tmp, &tomoyo_io_buffer_list,
 606                                         list) {
 607                        if (head->users)
 608                                continue;
 609                        list_del(&head->list);
 610                        kfree(head->read_buf);
 611                        kfree(head->write_buf);
 612                        kfree(head);
 613                }
 614                spin_unlock(&tomoyo_io_buffer_list_lock);
 615        }
 616        mutex_unlock(&tomoyo_gc_mutex);
 617out:
 618        /* This acts as do_exit(0). */
 619        return 0;
 620}
 621
 622/**
 623 * tomoyo_notify_gc - Register/unregister /sys/kernel/security/tomoyo/ users.
 624 *
 625 * @head:        Pointer to "struct tomoyo_io_buffer".
 626 * @is_register: True if register, false if unregister.
 627 *
 628 * Returns nothing.
 629 */
 630void tomoyo_notify_gc(struct tomoyo_io_buffer *head, const bool is_register)
 631{
 632        bool is_write = false;
 633
 634        spin_lock(&tomoyo_io_buffer_list_lock);
 635        if (is_register) {
 636                head->users = 1;
 637                list_add(&head->list, &tomoyo_io_buffer_list);
 638        } else {
 639                is_write = head->write_buf != NULL;
 640                if (!--head->users) {
 641                        list_del(&head->list);
 642                        kfree(head->read_buf);
 643                        kfree(head->write_buf);
 644                        kfree(head);
 645                }
 646        }
 647        spin_unlock(&tomoyo_io_buffer_list_lock);
 648        if (is_write) {
 649                struct task_struct *task = kthread_create(tomoyo_gc_thread,
 650                                                          NULL,
 651                                                          "GC for TOMOYO");
 652                if (!IS_ERR(task))
 653                        wake_up_process(task);
 654        }
 655}
 656
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.