security/tomoyo/gc.c

   1 /*
   2  * security/tomoyo/gc.c
   3  *
   4  * Implementation of the Domain-Based Mandatory Access Control.
   5  *
   6  * Copyright (C) 2005-2010  NTT DATA CORPORATION
   7  *
   8  */
   9
  10 #include "common.h"
  11 #include <linux/kthread.h>
  12 #include <linux/slab.h>
  13
  14 enum tomoyo_gc_id {
  15         TOMOYO_ID_PATH_GROUP,
  16         TOMOYO_ID_PATH_GROUP_MEMBER,
  17         TOMOYO_ID_NUMBER_GROUP,
  18         TOMOYO_ID_NUMBER_GROUP_MEMBER,
  19         TOMOYO_ID_DOMAIN_INITIALIZER,
  20         TOMOYO_ID_DOMAIN_KEEPER,
  21         TOMOYO_ID_ALIAS,
  22         TOMOYO_ID_GLOBALLY_READABLE,
  23         TOMOYO_ID_PATTERN,
  24         TOMOYO_ID_NO_REWRITE,
  25         TOMOYO_ID_MANAGER,
  26         TOMOYO_ID_NAME,
  27         TOMOYO_ID_ACL,
  28         TOMOYO_ID_DOMAIN
  29 };
  30
  31 struct tomoyo_gc_entry {
  32         struct list_head list;
  33         int type;
  34         void *element;
  35 };
  36 static LIST_HEAD(tomoyo_gc_queue);
  37 static DEFINE_MUTEX(tomoyo_gc_mutex);
  38
  39 /* Caller holds tomoyo_policy_lock mutex. */
  40 static bool tomoyo_add_to_gc(const int type, void *element)
  41 {
  42         struct tomoyo_gc_entry *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
  43         if (!entry)
  44                 return false;
  45         entry->type = type;
  46         entry->element = element;
  47         list_add(&entry->list, &tomoyo_gc_queue);
  48         return true;
  49 }
  50
  51 static void tomoyo_del_allow_read
  52 (struct tomoyo_globally_readable_file_entry *ptr)
  53 {
  54         tomoyo_put_name(ptr->filename);
  55 }
  56
  57 static void tomoyo_del_file_pattern(struct tomoyo_pattern_entry *ptr)
  58 {
  59         tomoyo_put_name(ptr->pattern);
  60 }
  61
  62 static void tomoyo_del_no_rewrite(struct tomoyo_no_rewrite_entry *ptr)
  63 {
  64         tomoyo_put_name(ptr->pattern);
  65 }
  66
  67 static void tomoyo_del_domain_initializer
  68 (struct tomoyo_domain_initializer_entry *ptr)
  69 {
  70         tomoyo_put_name(ptr->domainname);
  71         tomoyo_put_name(ptr->program);
  72 }
  73
  74 static void tomoyo_del_domain_keeper(struct tomoyo_domain_keeper_entry *ptr)
  75 {
  76         tomoyo_put_name(ptr->domainname);
  77         tomoyo_put_name(ptr->program);
  78 }
  79
  80 static void tomoyo_del_alias(struct tomoyo_alias_entry *ptr)
  81 {
  82         tomoyo_put_name(ptr->original_name);
  83         tomoyo_put_name(ptr->aliased_name);
  84 }
  85
  86 static void tomoyo_del_manager(struct tomoyo_policy_manager_entry *ptr)
  87 {
  88         tomoyo_put_name(ptr->manager);
  89 }
  90
  91 static void tomoyo_del_acl(struct tomoyo_acl_info *acl)
  92 {
  93         switch (acl->type) {
  94         case TOMOYO_TYPE_PATH_ACL:
  95                 {
  96                         struct tomoyo_path_acl *entry
  97                                 = container_of(acl, typeof(*entry), head);
  98                         tomoyo_put_name_union(&entry->name);
  99                 }
 100                 break;
 101         case TOMOYO_TYPE_PATH2_ACL:
 102                 {
 103                         struct tomoyo_path2_acl *entry
 104                                 = container_of(acl, typeof(*entry), head);
 105                         tomoyo_put_name_union(&entry->name1);
 106                         tomoyo_put_name_union(&entry->name2);
 107                 }
 108                 break;
 109         case TOMOYO_TYPE_PATH_NUMBER_ACL:
 110                 {
 111                         struct tomoyo_path_number_acl *entry
 112                                 = container_of(acl, typeof(*entry), head);
 113                         tomoyo_put_name_union(&entry->name);
 114                         tomoyo_put_number_union(&entry->number);
 115                 }
 116                 break;
 117         case TOMOYO_TYPE_PATH_NUMBER3_ACL:
 118                 {
 119                         struct tomoyo_path_number3_acl *entry
 120                                 = container_of(acl, typeof(*entry), head);
 121                         tomoyo_put_name_union(&entry->name);
 122                         tomoyo_put_number_union(&entry->mode);
 123                         tomoyo_put_number_union(&entry->major);
 124                         tomoyo_put_number_union(&entry->minor);
 125                 }
 126                 break;
 127         case TOMOYO_TYPE_MOUNT_ACL:
 128                 {
 129                         struct tomoyo_mount_acl *entry
 130                                 = container_of(acl, typeof(*entry), head);
 131                         tomoyo_put_name_union(&entry->dev_name);
 132                         tomoyo_put_name_union(&entry->dir_name);
 133                         tomoyo_put_name_union(&entry->fs_type);
 134                         tomoyo_put_number_union(&entry->flags);
 135                 }
 136                 break;
 137         default:
 138                 printk(KERN_WARNING "Unknown type\n");
 139                 break;
 140         }
 141 }
 142
 143 static bool tomoyo_del_domain(struct tomoyo_domain_info *domain)
 144 {
 145         struct tomoyo_acl_info *acl;
 146         struct tomoyo_acl_info *tmp;
 147         /*
 148          * Since we don't protect whole execve() operation using SRCU,
 149          * we need to recheck domain->users at this point.
 150          *
 151          * (1) Reader starts SRCU section upon execve().
 152          * (2) Reader traverses tomoyo_domain_list and finds this domain.
 153          * (3) Writer marks this domain as deleted.
 154          * (4) Garbage collector removes this domain from tomoyo_domain_list
 155          *     because this domain is marked as deleted and used by nobody.
 156          * (5) Reader saves reference to this domain into
 157          *     "struct linux_binprm"->cred->security .
 158          * (6) Reader finishes SRCU section, although execve() operation has
 159          *     not finished yet.
 160          * (7) Garbage collector waits for SRCU synchronization.
 161          * (8) Garbage collector kfree() this domain because this domain is
 162          *     used by nobody.
 163          * (9) Reader finishes execve() operation and restores this domain from
 164          *     "struct linux_binprm"->cred->security.
 165          *
 166          * By updating domain->users at (5), we can solve this race problem
 167          * by rechecking domain->users at (8).
 168          */
 169         if (atomic_read(&domain->users))
 170                 return false;
 171         list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
 172                 tomoyo_del_acl(acl);
 173                 tomoyo_memory_free(acl);
 174         }
 175         tomoyo_put_name(domain->domainname);
 176         return true;
 177 }
 178
 179
 180 static void tomoyo_del_name(const struct tomoyo_name_entry *ptr)
 181 {
 182 }
 183
 184 static void tomoyo_del_path_group_member(struct tomoyo_path_group_member
 185                                          *member)
 186 {
 187         tomoyo_put_name(member->member_name);
 188 }
 189
 190 static void tomoyo_del_path_group(struct tomoyo_path_group *group)
 191 {
 192         tomoyo_put_name(group->group_name);
 193 }
 194
 195 static void tomoyo_del_number_group_member(struct tomoyo_number_group_member
 196                                            *member)
 197 {
 198 }
 199
 200 static void tomoyo_del_number_group(struct tomoyo_number_group *group)
 201 {
 202         tomoyo_put_name(group->group_name);
 203 }
 204
 205 static void tomoyo_collect_entry(void)
 206 {
 207         if (mutex_lock_interruptible(&tomoyo_policy_lock))
 208                 return;
 209         {
 210                 struct tomoyo_globally_readable_file_entry *ptr;
 211                 list_for_each_entry_rcu(ptr, &tomoyo_globally_readable_list,
 212                                         list) {
 213                         if (!ptr->is_deleted)
 214                                 continue;
 215                         if (tomoyo_add_to_gc(TOMOYO_ID_GLOBALLY_READABLE, ptr))
 216                                 list_del_rcu(&ptr->list);
 217                         else
 218                                 break;
 219                 }
 220         }
 221         {
 222                 struct tomoyo_pattern_entry *ptr;
 223                 list_for_each_entry_rcu(ptr, &tomoyo_pattern_list, list) {
 224                         if (!ptr->is_deleted)
 225                                 continue;
 226                         if (tomoyo_add_to_gc(TOMOYO_ID_PATTERN, ptr))
 227                                 list_del_rcu(&ptr->list);
 228                         else
 229                                 break;
 230                 }
 231         }
 232         {
 233                 struct tomoyo_no_rewrite_entry *ptr;
 234                 list_for_each_entry_rcu(ptr, &tomoyo_no_rewrite_list, list) {
 235                         if (!ptr->is_deleted)
 236                                 continue;
 237                         if (tomoyo_add_to_gc(TOMOYO_ID_NO_REWRITE, ptr))
 238                                 list_del_rcu(&ptr->list);
 239                         else
 240                                 break;
 241                 }
 242         }
 243         {
 244                 struct tomoyo_domain_initializer_entry *ptr;
 245                 list_for_each_entry_rcu(ptr, &tomoyo_domain_initializer_list,
 246                                         list) {
 247                         if (!ptr->is_deleted)
 248                                 continue;
 249                         if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_INITIALIZER, ptr))
 250                                 list_del_rcu(&ptr->list);
 251                         else
 252                                 break;
 253                 }
 254         }
 255         {
 256                 struct tomoyo_domain_keeper_entry *ptr;
 257                 list_for_each_entry_rcu(ptr, &tomoyo_domain_keeper_list, list) {
 258                         if (!ptr->is_deleted)
 259                                 continue;
 260                         if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN_KEEPER, ptr))
 261                                 list_del_rcu(&ptr->list);
 262                         else
 263                                 break;
 264                 }
 265         }
 266         {
 267                 struct tomoyo_alias_entry *ptr;
 268                 list_for_each_entry_rcu(ptr, &tomoyo_alias_list, list) {
 269                         if (!ptr->is_deleted)
 270                                 continue;
 271                         if (tomoyo_add_to_gc(TOMOYO_ID_ALIAS, ptr))
 272                                 list_del_rcu(&ptr->list);
 273                         else
 274                                 break;
 275                 }
 276         }
 277         {
 278                 struct tomoyo_policy_manager_entry *ptr;
 279                 list_for_each_entry_rcu(ptr, &tomoyo_policy_manager_list,
 280                                         list) {
 281                         if (!ptr->is_deleted)
 282                                 continue;
 283                         if (tomoyo_add_to_gc(TOMOYO_ID_MANAGER, ptr))
 284                                 list_del_rcu(&ptr->list);
 285                         else
 286                                 break;
 287                 }
 288         }
 289         {
 290                 struct tomoyo_domain_info *domain;
 291                 list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
 292                         struct tomoyo_acl_info *acl;
 293                         list_for_each_entry_rcu(acl, &domain->acl_info_list,
 294                                                 list) {
 295                                 switch (acl->type) {
 296                                 case TOMOYO_TYPE_PATH_ACL:
 297                                         if (container_of(acl,
 298                                          struct tomoyo_path_acl,
 299                                                          head)->perm)
 300                                                 continue;
 301                                         break;
 302                                 case TOMOYO_TYPE_PATH2_ACL:
 303                                         if (container_of(acl,
 304                                          struct tomoyo_path2_acl,
 305                                                          head)->perm)
 306                                                 continue;
 307                                         break;
 308                                 case TOMOYO_TYPE_PATH_NUMBER_ACL:
 309                                         if (container_of(acl,
 310                                          struct tomoyo_path_number_acl,
 311                                                          head)->perm)
 312                                                 continue;
 313                                         break;
 314                                 case TOMOYO_TYPE_PATH_NUMBER3_ACL:
 315                                         if (container_of(acl,
 316                                          struct tomoyo_path_number3_acl,
 317                                                          head)->perm)
 318                                                 continue;
 319                                         break;
 320                                 default:
 321                                         continue;
 322                                 }
 323                                 if (tomoyo_add_to_gc(TOMOYO_ID_ACL, acl))
 324                                         list_del_rcu(&acl->list);
 325                                 else
 326                                         break;
 327                         }
 328                         if (!domain->is_deleted || atomic_read(&domain->users))
 329                                 continue;
 330                         /*
 331                          * Nobody is referring this domain. But somebody may
 332                          * refer this domain after successful execve().
 333                          * We recheck domain->users after SRCU synchronization.
 334                          */
 335                         if (tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, domain))
 336                                 list_del_rcu(&domain->list);
 337                         else
 338                                 break;
 339                 }
 340         }
 341         {
 342                 int i;
 343                 for (i = 0; i < TOMOYO_MAX_HASH; i++) {
 344                         struct tomoyo_name_entry *ptr;
 345                         list_for_each_entry_rcu(ptr, &tomoyo_name_list[i],
 346                                                 list) {
 347                                 if (atomic_read(&ptr->users))
 348                                         continue;
 349                                 if (tomoyo_add_to_gc(TOMOYO_ID_NAME, ptr))
 350                                         list_del_rcu(&ptr->list);
 351                                 else {
 352                                         i = TOMOYO_MAX_HASH;
 353                                         break;
 354                                 }
 355                         }
 356                 }
 357         }
 358         {
 359                 struct tomoyo_path_group *group;
 360                 list_for_each_entry_rcu(group, &tomoyo_path_group_list, list) {
 361                         struct tomoyo_path_group_member *member;
 362                         list_for_each_entry_rcu(member, &group->member_list,
 363                                                 list) {
 364                                 if (!member->is_deleted)
 365                                         continue;
 366                                 if (tomoyo_add_to_gc(TOMOYO_ID_PATH_GROUP_MEMBER,
 367                                                      member))
 368                                         list_del_rcu(&member->list);
 369                                 else
 370                                         break;
 371                         }
 372                         if (!list_empty(&group->member_list) ||
 373                             atomic_read(&group->users))
 374                                 continue;
 375                         if (tomoyo_add_to_gc(TOMOYO_ID_PATH_GROUP, group))
 376                                 list_del_rcu(&group->list);
 377                         else
 378                                 break;
 379                 }
 380         }
 381         {
 382                 struct tomoyo_number_group *group;
 383                 list_for_each_entry_rcu(group, &tomoyo_number_group_list, list) {
 384                         struct tomoyo_number_group_member *member;
 385                         list_for_each_entry_rcu(member, &group->member_list,
 386                                                 list) {
 387                                 if (!member->is_deleted)
 388                                         continue;
 389                                 if (tomoyo_add_to_gc(TOMOYO_ID_NUMBER_GROUP_MEMBER,
 390                                                      member))
 391                                         list_del_rcu(&member->list);
 392                                 else
 393                                         break;
 394                         }
 395                         if (!list_empty(&group->member_list) ||
 396                             atomic_read(&group->users))
 397                                 continue;
 398                         if (tomoyo_add_to_gc(TOMOYO_ID_NUMBER_GROUP, group))
 399                                 list_del_rcu(&group->list);
 400                         else
 401                                 break;
 402                 }
 403         }
 404         mutex_unlock(&tomoyo_policy_lock);
 405 }
 406
 407 static void tomoyo_kfree_entry(void)
 408 {
 409         struct tomoyo_gc_entry *p;
 410         struct tomoyo_gc_entry *tmp;
 411
 412         list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
 413                 switch (p->type) {
 414                 case TOMOYO_ID_DOMAIN_INITIALIZER:
 415                         tomoyo_del_domain_initializer(p->element);
 416                         break;
 417                 case TOMOYO_ID_DOMAIN_KEEPER:
 418                         tomoyo_del_domain_keeper(p->element);
 419                         break;
 420                 case TOMOYO_ID_ALIAS:
 421                         tomoyo_del_alias(p->element);
 422                         break;
 423                 case TOMOYO_ID_GLOBALLY_READABLE:
 424                         tomoyo_del_allow_read(p->element);
 425                         break;
 426                 case TOMOYO_ID_PATTERN:
 427                         tomoyo_del_file_pattern(p->element);
 428                         break;
 429                 case TOMOYO_ID_NO_REWRITE:
 430                         tomoyo_del_no_rewrite(p->element);
 431                         break;
 432                 case TOMOYO_ID_MANAGER:
 433                         tomoyo_del_manager(p->element);
 434                         break;
 435                 case TOMOYO_ID_NAME:
 436                         tomoyo_del_name(p->element);
 437                         break;
 438                 case TOMOYO_ID_ACL:
 439                         tomoyo_del_acl(p->element);
 440                         break;
 441                 case TOMOYO_ID_DOMAIN:
 442                         if (!tomoyo_del_domain(p->element))
 443                                 continue;
 444                         break;
 445                 case TOMOYO_ID_PATH_GROUP_MEMBER:
 446                         tomoyo_del_path_group_member(p->element);
 447                         break;
 448                 case TOMOYO_ID_PATH_GROUP:
 449                         tomoyo_del_path_group(p->element);
 450                         break;
 451                 case TOMOYO_ID_NUMBER_GROUP_MEMBER:
 452                         tomoyo_del_number_group_member(p->element);
 453                         break;
 454                 case TOMOYO_ID_NUMBER_GROUP:
 455                         tomoyo_del_number_group(p->element);
 456                         break;
 457                 default:
 458                         printk(KERN_WARNING "Unknown type\n");
 459                         break;
 460                 }
 461                 tomoyo_memory_free(p->element);
 462                 list_del(&p->list);
 463                 kfree(p);
 464         }
 465 }
 466
 467 static int tomoyo_gc_thread(void *unused)
 468 {
 469         daemonize("GC for TOMOYO");
 470         if (mutex_trylock(&tomoyo_gc_mutex)) {
 471                 int i;
 472                 for (i = 0; i < 10; i++) {
 473                         tomoyo_collect_entry();
 474                         if (list_empty(&tomoyo_gc_queue))
 475                                 break;
 476                         synchronize_srcu(&tomoyo_ss);
 477                         tomoyo_kfree_entry();
 478                 }
 479                 mutex_unlock(&tomoyo_gc_mutex);
 480         }
 481         do_exit(0);
 482 }
 483
 484 void tomoyo_run_gc(void)
 485 {
 486         struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
 487                                                   "GC for TOMOYO");
 488         if (!IS_ERR(task))
 489                 wake_up_process(task);
 490 }