kernel/audit_tree.c

   1 #include "audit.h"
   2 #include <linux/fsnotify_backend.h>
   3 #include <linux/namei.h>
   4 #include <linux/mount.h>
   5 #include <linux/kthread.h>
   6 #include <linux/slab.h>
   7
   8 struct audit_tree;
   9 struct audit_chunk;
  10
  11 struct audit_tree {
  12         atomic_t count;
  13         int goner;
  14         struct audit_chunk *root;
  15         struct list_head chunks;
  16         struct list_head rules;
  17         struct list_head list;
  18         struct list_head same_root;
  19         struct rcu_head head;
  20         char pathname[];
  21 };
  22
  23 struct audit_chunk {
  24         struct list_head hash;
  25         struct fsnotify_mark mark;
  26         struct list_head trees;         /* with root here */
  27         int dead;
  28         int count;
  29         atomic_long_t refs;
  30         struct rcu_head head;
  31         struct node {
  32                 struct list_head list;
  33                 struct audit_tree *owner;
  34                 unsigned index;         /* index; upper bit indicates 'will prune' */
  35         } owners[];
  36 };
  37
  38 static LIST_HEAD(tree_list);
  39 static LIST_HEAD(prune_list);
  40 static struct task_struct *prune_thread;
  41
  42 /*
  43  * One struct chunk is attached to each inode of interest.
  44  * We replace struct chunk on tagging/untagging.
  45  * Rules have pointer to struct audit_tree.
  46  * Rules have struct list_head rlist forming a list of rules over
  47  * the same tree.
  48  * References to struct chunk are collected at audit_inode{,_child}()
  49  * time and used in AUDIT_TREE rule matching.
  50  * These references are dropped at the same time we are calling
  51  * audit_free_names(), etc.
  52  *
  53  * Cyclic lists galore:
  54  * tree.chunks anchors chunk.owners[].list                      hash_lock
  55  * tree.rules anchors rule.rlist                                audit_filter_mutex
  56  * chunk.trees anchors tree.same_root                           hash_lock
  57  * chunk.hash is a hash with middle bits of watch.inode as
  58  * a hash function.                                             RCU, hash_lock
  59  *
  60  * tree is refcounted; one reference for "some rules on rules_list refer to
  61  * it", one for each chunk with pointer to it.
  62  *
  63  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
  64  * of watch contributes 1 to .refs).
  65  *
  66  * node.index allows to get from node.list to containing chunk.
  67  * MSB of that sucker is stolen to mark taggings that we might have to
  68  * revert - several operations have very unpleasant cleanup logics and
  69  * that makes a difference.  Some.
  70  */
  71
  72 static struct fsnotify_group *audit_tree_group;
  73
  74 static struct audit_tree *alloc_tree(const char *s)
  75 {
  76         struct audit_tree *tree;
  77
  78         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
  79         if (tree) {
  80                 atomic_set(&tree->count, 1);
  81                 tree->goner = 0;
  82                 INIT_LIST_HEAD(&tree->chunks);
  83                 INIT_LIST_HEAD(&tree->rules);
  84                 INIT_LIST_HEAD(&tree->list);
  85                 INIT_LIST_HEAD(&tree->same_root);
  86                 tree->root = NULL;
  87                 strcpy(tree->pathname, s);
  88         }
  89         return tree;
  90 }
  91
  92 static inline void get_tree(struct audit_tree *tree)
  93 {
  94         atomic_inc(&tree->count);
  95 }
  96
  97 static inline void put_tree(struct audit_tree *tree)
  98 {
  99         if (atomic_dec_and_test(&tree->count))
 100                 kfree_rcu(tree, head);
 101 }
 102
 103 /* to avoid bringing the entire thing in audit.h */
 104 const char *audit_tree_path(struct audit_tree *tree)
 105 {
 106         return tree->pathname;
 107 }
 108
 109 static void free_chunk(struct audit_chunk *chunk)
 110 {
 111         int i;
 112
 113         for (i = 0; i < chunk->count; i++) {
 114                 if (chunk->owners[i].owner)
 115                         put_tree(chunk->owners[i].owner);
 116         }
 117         kfree(chunk);
 118 }
 119
 120 void audit_put_chunk(struct audit_chunk *chunk)
 121 {
 122         if (atomic_long_dec_and_test(&chunk->refs))
 123                 free_chunk(chunk);
 124 }
 125
 126 static void __put_chunk(struct rcu_head *rcu)
 127 {
 128         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
 129         audit_put_chunk(chunk);
 130 }
 131
 132 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
 133 {
 134         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 135         call_rcu(&chunk->head, __put_chunk);
 136 }
 137
 138 static struct audit_chunk *alloc_chunk(int count)
 139 {
 140         struct audit_chunk *chunk;
 141         size_t size;
 142         int i;
 143
 144         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
 145         chunk = kzalloc(size, GFP_KERNEL);
 146         if (!chunk)
 147                 return NULL;
 148
 149         INIT_LIST_HEAD(&chunk->hash);
 150         INIT_LIST_HEAD(&chunk->trees);
 151         chunk->count = count;
 152         atomic_long_set(&chunk->refs, 1);
 153         for (i = 0; i < count; i++) {
 154                 INIT_LIST_HEAD(&chunk->owners[i].list);
 155                 chunk->owners[i].index = i;
 156         }
 157         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
 158         chunk->mark.mask = FS_IN_IGNORED;
 159         return chunk;
 160 }
 161
 162 enum {HASH_SIZE = 128};
 163 static struct list_head chunk_hash_heads[HASH_SIZE];
 164 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
 165
 166 /* Function to return search key in our hash from inode. */
 167 static unsigned long inode_to_key(const struct inode *inode)
 168 {
 169         return (unsigned long)inode;
 170 }
 171
 172 /*
 173  * Function to return search key in our hash from chunk. Key 0 is special and
 174  * should never be present in the hash.
 175  */
 176 static unsigned long chunk_to_key(struct audit_chunk *chunk)
 177 {
 178         return (unsigned long)chunk->mark.inode;
 179 }
 180
 181 static inline struct list_head *chunk_hash(unsigned long key)
 182 {
 183         unsigned long n = key / L1_CACHE_BYTES;
 184         return chunk_hash_heads + n % HASH_SIZE;
 185 }
 186
 187 /* hash_lock & entry->lock is held by caller */
 188 static void insert_hash(struct audit_chunk *chunk)
 189 {
 190         unsigned long key = chunk_to_key(chunk);
 191         struct list_head *list;
 192
 193         if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED))
 194                 return;
 195         list = chunk_hash(key);
 196         list_add_rcu(&chunk->hash, list);
 197 }
 198
 199 /* called under rcu_read_lock */
 200 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
 201 {
 202         unsigned long key = inode_to_key(inode);
 203         struct list_head *list = chunk_hash(key);
 204         struct audit_chunk *p;
 205
 206         list_for_each_entry_rcu(p, list, hash) {
 207                 if (chunk_to_key(p) == key) {
 208                         atomic_long_inc(&p->refs);
 209                         return p;
 210                 }
 211         }
 212         return NULL;
 213 }
 214
 215 bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
 216 {
 217         int n;
 218         for (n = 0; n < chunk->count; n++)
 219                 if (chunk->owners[n].owner == tree)
 220                         return true;
 221         return false;
 222 }
 223
 224 /* tagging and untagging inodes with trees */
 225
 226 static struct audit_chunk *find_chunk(struct node *p)
 227 {
 228         int index = p->index & ~(1U<<31);
 229         p -= index;
 230         return container_of(p, struct audit_chunk, owners[0]);
 231 }
 232
 233 static void untag_chunk(struct node *p)
 234 {
 235         struct audit_chunk *chunk = find_chunk(p);
 236         struct fsnotify_mark *entry = &chunk->mark;
 237         struct audit_chunk *new = NULL;
 238         struct audit_tree *owner;
 239         int size = chunk->count - 1;
 240         int i, j;
 241
 242         fsnotify_get_mark(entry);
 243
 244         spin_unlock(&hash_lock);
 245
 246         if (size)
 247                 new = alloc_chunk(size);
 248
 249         mutex_lock(&entry->group->mark_mutex);
 250         spin_lock(&entry->lock);
 251         if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
 252                 spin_unlock(&entry->lock);
 253                 mutex_unlock(&entry->group->mark_mutex);
 254                 if (new)
 255                         free_chunk(new);
 256                 goto out;
 257         }
 258
 259         owner = p->owner;
 260
 261         if (!size) {
 262                 chunk->dead = 1;
 263                 spin_lock(&hash_lock);
 264                 list_del_init(&chunk->trees);
 265                 if (owner->root == chunk)
 266                         owner->root = NULL;
 267                 list_del_init(&p->list);
 268                 list_del_rcu(&chunk->hash);
 269                 spin_unlock(&hash_lock);
 270                 spin_unlock(&entry->lock);
 271                 mutex_unlock(&entry->group->mark_mutex);
 272                 fsnotify_destroy_mark(entry, audit_tree_group);
 273                 goto out;
 274         }
 275
 276         if (!new)
 277                 goto Fallback;
 278
 279         if (fsnotify_add_mark_locked(&new->mark, entry->group, entry->inode,
 280                                      NULL, 1)) {
 281                 fsnotify_put_mark(&new->mark);
 282                 goto Fallback;
 283         }
 284
 285         chunk->dead = 1;
 286         spin_lock(&hash_lock);
 287         list_replace_init(&chunk->trees, &new->trees);
 288         if (owner->root == chunk) {
 289                 list_del_init(&owner->same_root);
 290                 owner->root = NULL;
 291         }
 292
 293         for (i = j = 0; j <= size; i++, j++) {
 294                 struct audit_tree *s;
 295                 if (&chunk->owners[j] == p) {
 296                         list_del_init(&p->list);
 297                         i--;
 298                         continue;
 299                 }
 300                 s = chunk->owners[j].owner;
 301                 new->owners[i].owner = s;
 302                 new->owners[i].index = chunk->owners[j].index - j + i;
 303                 if (!s) /* result of earlier fallback */
 304                         continue;
 305                 get_tree(s);
 306                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
 307         }
 308
 309         list_replace_rcu(&chunk->hash, &new->hash);
 310         list_for_each_entry(owner, &new->trees, same_root)
 311                 owner->root = new;
 312         spin_unlock(&hash_lock);
 313         spin_unlock(&entry->lock);
 314         mutex_unlock(&entry->group->mark_mutex);
 315         fsnotify_destroy_mark(entry, audit_tree_group);
 316         fsnotify_put_mark(&new->mark);  /* drop initial reference */
 317         goto out;
 318
 319 Fallback:
 320         // do the best we can
 321         spin_lock(&hash_lock);
 322         if (owner->root == chunk) {
 323                 list_del_init(&owner->same_root);
 324                 owner->root = NULL;
 325         }
 326         list_del_init(&p->list);
 327         p->owner = NULL;
 328         put_tree(owner);
 329         spin_unlock(&hash_lock);
 330         spin_unlock(&entry->lock);
 331         mutex_unlock(&entry->group->mark_mutex);
 332 out:
 333         fsnotify_put_mark(entry);
 334         spin_lock(&hash_lock);
 335 }
 336
 337 static int create_chunk(struct inode *inode, struct audit_tree *tree)
 338 {
 339         struct fsnotify_mark *entry;
 340         struct audit_chunk *chunk = alloc_chunk(1);
 341         if (!chunk)
 342                 return -ENOMEM;
 343
 344         entry = &chunk->mark;
 345         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
 346                 fsnotify_put_mark(entry);
 347                 return -ENOSPC;
 348         }
 349
 350         spin_lock(&entry->lock);
 351         spin_lock(&hash_lock);
 352         if (tree->goner) {
 353                 spin_unlock(&hash_lock);
 354                 chunk->dead = 1;
 355                 spin_unlock(&entry->lock);
 356                 fsnotify_destroy_mark(entry, audit_tree_group);
 357                 fsnotify_put_mark(entry);
 358                 return 0;
 359         }
 360         chunk->owners[0].index = (1U << 31);
 361         chunk->owners[0].owner = tree;
 362         get_tree(tree);
 363         list_add(&chunk->owners[0].list, &tree->chunks);
 364         if (!tree->root) {
 365                 tree->root = chunk;
 366                 list_add(&tree->same_root, &chunk->trees);
 367         }
 368         insert_hash(chunk);
 369         spin_unlock(&hash_lock);
 370         spin_unlock(&entry->lock);
 371         fsnotify_put_mark(entry);       /* drop initial reference */
 372         return 0;
 373 }
 374
 375 /* the first tagged inode becomes root of tree */
 376 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 377 {
 378         struct fsnotify_mark *old_entry, *chunk_entry;
 379         struct audit_tree *owner;
 380         struct audit_chunk *chunk, *old;
 381         struct node *p;
 382         int n;
 383
 384         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
 385         if (!old_entry)
 386                 return create_chunk(inode, tree);
 387
 388         old = container_of(old_entry, struct audit_chunk, mark);
 389
 390         /* are we already there? */
 391         spin_lock(&hash_lock);
 392         for (n = 0; n < old->count; n++) {
 393                 if (old->owners[n].owner == tree) {
 394                         spin_unlock(&hash_lock);
 395                         fsnotify_put_mark(old_entry);
 396                         return 0;
 397                 }
 398         }
 399         spin_unlock(&hash_lock);
 400
 401         chunk = alloc_chunk(old->count + 1);
 402         if (!chunk) {
 403                 fsnotify_put_mark(old_entry);
 404                 return -ENOMEM;
 405         }
 406
 407         chunk_entry = &chunk->mark;
 408
 409         mutex_lock(&old_entry->group->mark_mutex);
 410         spin_lock(&old_entry->lock);
 411         if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
 412                 /* old_entry is being shot, lets just lie */
 413                 spin_unlock(&old_entry->lock);
 414                 mutex_unlock(&old_entry->group->mark_mutex);
 415                 fsnotify_put_mark(old_entry);
 416                 free_chunk(chunk);
 417                 return -ENOENT;
 418         }
 419
 420         if (fsnotify_add_mark_locked(chunk_entry, old_entry->group,
 421                                      old_entry->inode, NULL, 1)) {
 422                 spin_unlock(&old_entry->lock);
 423                 mutex_unlock(&old_entry->group->mark_mutex);
 424                 fsnotify_put_mark(chunk_entry);
 425                 fsnotify_put_mark(old_entry);
 426                 return -ENOSPC;
 427         }
 428
 429         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
 430         spin_lock(&chunk_entry->lock);
 431         spin_lock(&hash_lock);
 432
 433         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
 434         if (tree->goner) {
 435                 spin_unlock(&hash_lock);
 436                 chunk->dead = 1;
 437                 spin_unlock(&chunk_entry->lock);
 438                 spin_unlock(&old_entry->lock);
 439                 mutex_unlock(&old_entry->group->mark_mutex);
 440
 441                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
 442
 443                 fsnotify_put_mark(chunk_entry);
 444                 fsnotify_put_mark(old_entry);
 445                 return 0;
 446         }
 447         list_replace_init(&old->trees, &chunk->trees);
 448         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
 449                 struct audit_tree *s = old->owners[n].owner;
 450                 p->owner = s;
 451                 p->index = old->owners[n].index;
 452                 if (!s) /* result of fallback in untag */
 453                         continue;
 454                 get_tree(s);
 455                 list_replace_init(&old->owners[n].list, &p->list);
 456         }
 457         p->index = (chunk->count - 1) | (1U<<31);
 458         p->owner = tree;
 459         get_tree(tree);
 460         list_add(&p->list, &tree->chunks);
 461         list_replace_rcu(&old->hash, &chunk->hash);
 462         list_for_each_entry(owner, &chunk->trees, same_root)
 463                 owner->root = chunk;
 464         old->dead = 1;
 465         if (!tree->root) {
 466                 tree->root = chunk;
 467                 list_add(&tree->same_root, &chunk->trees);
 468         }
 469         spin_unlock(&hash_lock);
 470         spin_unlock(&chunk_entry->lock);
 471         spin_unlock(&old_entry->lock);
 472         mutex_unlock(&old_entry->group->mark_mutex);
 473         fsnotify_destroy_mark(old_entry, audit_tree_group);
 474         fsnotify_put_mark(chunk_entry); /* drop initial reference */
 475         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
 476         return 0;
 477 }
 478
 479 static void audit_tree_log_remove_rule(struct audit_krule *rule)
 480 {
 481         struct audit_buffer *ab;
 482
 483         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
 484         if (unlikely(!ab))
 485                 return;
 486         audit_log_format(ab, "op=remove_rule");
 487         audit_log_format(ab, " dir=");
 488         audit_log_untrustedstring(ab, rule->tree->pathname);
 489         audit_log_key(ab, rule->filterkey);
 490         audit_log_format(ab, " list=%d res=1", rule->listnr);
 491         audit_log_end(ab);
 492 }
 493
 494 static void kill_rules(struct audit_tree *tree)
 495 {
 496         struct audit_krule *rule, *next;
 497         struct audit_entry *entry;
 498
 499         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
 500                 entry = container_of(rule, struct audit_entry, rule);
 501
 502                 list_del_init(&rule->rlist);
 503                 if (rule->tree) {
 504                         /* not a half-baked one */
 505                         audit_tree_log_remove_rule(rule);
 506                         if (entry->rule.exe)
 507                                 audit_remove_mark(entry->rule.exe);
 508                         rule->tree = NULL;
 509                         list_del_rcu(&entry->list);
 510                         list_del(&entry->rule.list);
 511                         call_rcu(&entry->rcu, audit_free_rule_rcu);
 512                 }
 513         }
 514 }
 515
 516 /*
 517  * finish killing struct audit_tree
 518  */
 519 static void prune_one(struct audit_tree *victim)
 520 {
 521         spin_lock(&hash_lock);
 522         while (!list_empty(&victim->chunks)) {
 523                 struct node *p;
 524
 525                 p = list_entry(victim->chunks.next, struct node, list);
 526
 527                 untag_chunk(p);
 528         }
 529         spin_unlock(&hash_lock);
 530         put_tree(victim);
 531 }
 532
 533 /* trim the uncommitted chunks from tree */
 534
 535 static void trim_marked(struct audit_tree *tree)
 536 {
 537         struct list_head *p, *q;
 538         spin_lock(&hash_lock);
 539         if (tree->goner) {
 540                 spin_unlock(&hash_lock);
 541                 return;
 542         }
 543         /* reorder */
 544         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
 545                 struct node *node = list_entry(p, struct node, list);
 546                 q = p->next;
 547                 if (node->index & (1U<<31)) {
 548                         list_del_init(p);
 549                         list_add(p, &tree->chunks);
 550                 }
 551         }
 552
 553         while (!list_empty(&tree->chunks)) {
 554                 struct node *node;
 555
 556                 node = list_entry(tree->chunks.next, struct node, list);
 557
 558                 /* have we run out of marked? */
 559                 if (!(node->index & (1U<<31)))
 560                         break;
 561
 562                 untag_chunk(node);
 563         }
 564         if (!tree->root && !tree->goner) {
 565                 tree->goner = 1;
 566                 spin_unlock(&hash_lock);
 567                 mutex_lock(&audit_filter_mutex);
 568                 kill_rules(tree);
 569                 list_del_init(&tree->list);
 570                 mutex_unlock(&audit_filter_mutex);
 571                 prune_one(tree);
 572         } else {
 573                 spin_unlock(&hash_lock);
 574         }
 575 }
 576
 577 static void audit_schedule_prune(void);
 578
 579 /* called with audit_filter_mutex */
 580 int audit_remove_tree_rule(struct audit_krule *rule)
 581 {
 582         struct audit_tree *tree;
 583         tree = rule->tree;
 584         if (tree) {
 585                 spin_lock(&hash_lock);
 586                 list_del_init(&rule->rlist);
 587                 if (list_empty(&tree->rules) && !tree->goner) {
 588                         tree->root = NULL;
 589                         list_del_init(&tree->same_root);
 590                         tree->goner = 1;
 591                         list_move(&tree->list, &prune_list);
 592                         rule->tree = NULL;
 593                         spin_unlock(&hash_lock);
 594                         audit_schedule_prune();
 595                         return 1;
 596                 }
 597                 rule->tree = NULL;
 598                 spin_unlock(&hash_lock);
 599                 return 1;
 600         }
 601         return 0;
 602 }
 603
 604 static int compare_root(struct vfsmount *mnt, void *arg)
 605 {
 606         return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
 607                (unsigned long)arg;
 608 }
 609
 610 void audit_trim_trees(void)
 611 {
 612         struct list_head cursor;
 613
 614         mutex_lock(&audit_filter_mutex);
 615         list_add(&cursor, &tree_list);
 616         while (cursor.next != &tree_list) {
 617                 struct audit_tree *tree;
 618                 struct path path;
 619                 struct vfsmount *root_mnt;
 620                 struct node *node;
 621                 int err;
 622
 623                 tree = container_of(cursor.next, struct audit_tree, list);
 624                 get_tree(tree);
 625                 list_del(&cursor);
 626                 list_add(&cursor, &tree->list);
 627                 mutex_unlock(&audit_filter_mutex);
 628
 629                 err = kern_path(tree->pathname, 0, &path);
 630                 if (err)
 631                         goto skip_it;
 632
 633                 root_mnt = collect_mounts(&path);
 634                 path_put(&path);
 635                 if (IS_ERR(root_mnt))
 636                         goto skip_it;
 637
 638                 spin_lock(&hash_lock);
 639                 list_for_each_entry(node, &tree->chunks, list) {
 640                         struct audit_chunk *chunk = find_chunk(node);
 641                         /* this could be NULL if the watch is dying else where... */
 642                         node->index |= 1U<<31;
 643                         if (iterate_mounts(compare_root,
 644                                            (void *)chunk_to_key(chunk),
 645                                            root_mnt))
 646                                 node->index &= ~(1U<<31);
 647                 }
 648                 spin_unlock(&hash_lock);
 649                 trim_marked(tree);
 650                 drop_collected_mounts(root_mnt);
 651 skip_it:
 652                 put_tree(tree);
 653                 mutex_lock(&audit_filter_mutex);
 654         }
 655         list_del(&cursor);
 656         mutex_unlock(&audit_filter_mutex);
 657 }
 658
 659 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
 660 {
 661
 662         if (pathname[0] != '/' ||
 663             rule->listnr != AUDIT_FILTER_EXIT ||
 664             op != Audit_equal ||
 665             rule->inode_f || rule->watch || rule->tree)
 666                 return -EINVAL;
 667         rule->tree = alloc_tree(pathname);
 668         if (!rule->tree)
 669                 return -ENOMEM;
 670         return 0;
 671 }
 672
 673 void audit_put_tree(struct audit_tree *tree)
 674 {
 675         put_tree(tree);
 676 }
 677
 678 static int tag_mount(struct vfsmount *mnt, void *arg)
 679 {
 680         return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
 681 }
 682
 683 /*
 684  * That gets run when evict_chunk() ends up needing to kill audit_tree.
 685  * Runs from a separate thread.
 686  */
 687 static int prune_tree_thread(void *unused)
 688 {
 689         for (;;) {
 690                 if (list_empty(&prune_list)) {
 691                         set_current_state(TASK_INTERRUPTIBLE);
 692                         schedule();
 693                 }
 694
 695                 mutex_lock(&audit_cmd_mutex);
 696                 mutex_lock(&audit_filter_mutex);
 697
 698                 while (!list_empty(&prune_list)) {
 699                         struct audit_tree *victim;
 700
 701                         victim = list_entry(prune_list.next,
 702                                         struct audit_tree, list);
 703                         list_del_init(&victim->list);
 704
 705                         mutex_unlock(&audit_filter_mutex);
 706
 707                         prune_one(victim);
 708
 709                         mutex_lock(&audit_filter_mutex);
 710                 }
 711
 712                 mutex_unlock(&audit_filter_mutex);
 713                 mutex_unlock(&audit_cmd_mutex);
 714         }
 715         return 0;
 716 }
 717
 718 static int audit_launch_prune(void)
 719 {
 720         if (prune_thread)
 721                 return 0;
 722         prune_thread = kthread_run(prune_tree_thread, NULL,
 723                                 "audit_prune_tree");
 724         if (IS_ERR(prune_thread)) {
 725                 pr_err("cannot start thread audit_prune_tree");
 726                 prune_thread = NULL;
 727                 return -ENOMEM;
 728         }
 729         return 0;
 730 }
 731
 732 /* called with audit_filter_mutex */
 733 int audit_add_tree_rule(struct audit_krule *rule)
 734 {
 735         struct audit_tree *seed = rule->tree, *tree;
 736         struct path path;
 737         struct vfsmount *mnt;
 738         int err;
 739
 740         rule->tree = NULL;
 741         list_for_each_entry(tree, &tree_list, list) {
 742                 if (!strcmp(seed->pathname, tree->pathname)) {
 743                         put_tree(seed);
 744                         rule->tree = tree;
 745                         list_add(&rule->rlist, &tree->rules);
 746                         return 0;
 747                 }
 748         }
 749         tree = seed;
 750         list_add(&tree->list, &tree_list);
 751         list_add(&rule->rlist, &tree->rules);
 752         /* do not set rule->tree yet */
 753         mutex_unlock(&audit_filter_mutex);
 754
 755         if (unlikely(!prune_thread)) {
 756                 err = audit_launch_prune();
 757                 if (err)
 758                         goto Err;
 759         }
 760
 761         err = kern_path(tree->pathname, 0, &path);
 762         if (err)
 763                 goto Err;
 764         mnt = collect_mounts(&path);
 765         path_put(&path);
 766         if (IS_ERR(mnt)) {
 767                 err = PTR_ERR(mnt);
 768                 goto Err;
 769         }
 770
 771         get_tree(tree);
 772         err = iterate_mounts(tag_mount, tree, mnt);
 773         drop_collected_mounts(mnt);
 774
 775         if (!err) {
 776                 struct node *node;
 777                 spin_lock(&hash_lock);
 778                 list_for_each_entry(node, &tree->chunks, list)
 779                         node->index &= ~(1U<<31);
 780                 spin_unlock(&hash_lock);
 781         } else {
 782                 trim_marked(tree);
 783                 goto Err;
 784         }
 785
 786         mutex_lock(&audit_filter_mutex);
 787         if (list_empty(&rule->rlist)) {
 788                 put_tree(tree);
 789                 return -ENOENT;
 790         }
 791         rule->tree = tree;
 792         put_tree(tree);
 793
 794         return 0;
 795 Err:
 796         mutex_lock(&audit_filter_mutex);
 797         list_del_init(&tree->list);
 798         list_del_init(&tree->rules);
 799         put_tree(tree);
 800         return err;
 801 }
 802
 803 int audit_tag_tree(char *old, char *new)
 804 {
 805         struct list_head cursor, barrier;
 806         int failed = 0;
 807         struct path path1, path2;
 808         struct vfsmount *tagged;
 809         int err;
 810
 811         err = kern_path(new, 0, &path2);
 812         if (err)
 813                 return err;
 814         tagged = collect_mounts(&path2);
 815         path_put(&path2);
 816         if (IS_ERR(tagged))
 817                 return PTR_ERR(tagged);
 818
 819         err = kern_path(old, 0, &path1);
 820         if (err) {
 821                 drop_collected_mounts(tagged);
 822                 return err;
 823         }
 824
 825         mutex_lock(&audit_filter_mutex);
 826         list_add(&barrier, &tree_list);
 827         list_add(&cursor, &barrier);
 828
 829         while (cursor.next != &tree_list) {
 830                 struct audit_tree *tree;
 831                 int good_one = 0;
 832
 833                 tree = container_of(cursor.next, struct audit_tree, list);
 834                 get_tree(tree);
 835                 list_del(&cursor);
 836                 list_add(&cursor, &tree->list);
 837                 mutex_unlock(&audit_filter_mutex);
 838
 839                 err = kern_path(tree->pathname, 0, &path2);
 840                 if (!err) {
 841                         good_one = path_is_under(&path1, &path2);
 842                         path_put(&path2);
 843                 }
 844
 845                 if (!good_one) {
 846                         put_tree(tree);
 847                         mutex_lock(&audit_filter_mutex);
 848                         continue;
 849                 }
 850
 851                 failed = iterate_mounts(tag_mount, tree, tagged);
 852                 if (failed) {
 853                         put_tree(tree);
 854                         mutex_lock(&audit_filter_mutex);
 855                         break;
 856                 }
 857
 858                 mutex_lock(&audit_filter_mutex);
 859                 spin_lock(&hash_lock);
 860                 if (!tree->goner) {
 861                         list_del(&tree->list);
 862                         list_add(&tree->list, &tree_list);
 863                 }
 864                 spin_unlock(&hash_lock);
 865                 put_tree(tree);
 866         }
 867
 868         while (barrier.prev != &tree_list) {
 869                 struct audit_tree *tree;
 870
 871                 tree = container_of(barrier.prev, struct audit_tree, list);
 872                 get_tree(tree);
 873                 list_del(&tree->list);
 874                 list_add(&tree->list, &barrier);
 875                 mutex_unlock(&audit_filter_mutex);
 876
 877                 if (!failed) {
 878                         struct node *node;
 879                         spin_lock(&hash_lock);
 880                         list_for_each_entry(node, &tree->chunks, list)
 881                                 node->index &= ~(1U<<31);
 882                         spin_unlock(&hash_lock);
 883                 } else {
 884                         trim_marked(tree);
 885                 }
 886
 887                 put_tree(tree);
 888                 mutex_lock(&audit_filter_mutex);
 889         }
 890         list_del(&barrier);
 891         list_del(&cursor);
 892         mutex_unlock(&audit_filter_mutex);
 893         path_put(&path1);
 894         drop_collected_mounts(tagged);
 895         return failed;
 896 }
 897
 898
 899 static void audit_schedule_prune(void)
 900 {
 901         wake_up_process(prune_thread);
 902 }
 903
 904 /*
 905  * ... and that one is done if evict_chunk() decides to delay until the end
 906  * of syscall.  Runs synchronously.
 907  */
 908 void audit_kill_trees(struct list_head *list)
 909 {
 910         mutex_lock(&audit_cmd_mutex);
 911         mutex_lock(&audit_filter_mutex);
 912
 913         while (!list_empty(list)) {
 914                 struct audit_tree *victim;
 915
 916                 victim = list_entry(list->next, struct audit_tree, list);
 917                 kill_rules(victim);
 918                 list_del_init(&victim->list);
 919
 920                 mutex_unlock(&audit_filter_mutex);
 921
 922                 prune_one(victim);
 923
 924                 mutex_lock(&audit_filter_mutex);
 925         }
 926
 927         mutex_unlock(&audit_filter_mutex);
 928         mutex_unlock(&audit_cmd_mutex);
 929 }
 930
 931 /*
 932  *  Here comes the stuff asynchronous to auditctl operations
 933  */
 934
 935 static void evict_chunk(struct audit_chunk *chunk)
 936 {
 937         struct audit_tree *owner;
 938         struct list_head *postponed = audit_killed_trees();
 939         int need_prune = 0;
 940         int n;
 941
 942         if (chunk->dead)
 943                 return;
 944
 945         chunk->dead = 1;
 946         mutex_lock(&audit_filter_mutex);
 947         spin_lock(&hash_lock);
 948         while (!list_empty(&chunk->trees)) {
 949                 owner = list_entry(chunk->trees.next,
 950                                    struct audit_tree, same_root);
 951                 owner->goner = 1;
 952                 owner->root = NULL;
 953                 list_del_init(&owner->same_root);
 954                 spin_unlock(&hash_lock);
 955                 if (!postponed) {
 956                         kill_rules(owner);
 957                         list_move(&owner->list, &prune_list);
 958                         need_prune = 1;
 959                 } else {
 960                         list_move(&owner->list, postponed);
 961                 }
 962                 spin_lock(&hash_lock);
 963         }
 964         list_del_rcu(&chunk->hash);
 965         for (n = 0; n < chunk->count; n++)
 966                 list_del_init(&chunk->owners[n].list);
 967         spin_unlock(&hash_lock);
 968         mutex_unlock(&audit_filter_mutex);
 969         if (need_prune)
 970                 audit_schedule_prune();
 971 }
 972
 973 static int audit_tree_handle_event(struct fsnotify_group *group,
 974                                    struct inode *to_tell,
 975                                    struct fsnotify_mark *inode_mark,
 976                                    struct fsnotify_mark *vfsmount_mark,
 977                                    u32 mask, const void *data, int data_type,
 978                                    const unsigned char *file_name, u32 cookie)
 979 {
 980         return 0;
 981 }
 982
 983 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
 984 {
 985         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
 986
 987         evict_chunk(chunk);
 988
 989         /*
 990          * We are guaranteed to have at least one reference to the mark from
 991          * either the inode or the caller of fsnotify_destroy_mark().
 992          */
 993         BUG_ON(atomic_read(&entry->refcnt) < 1);
 994 }
 995
 996 static const struct fsnotify_ops audit_tree_ops = {
 997         .handle_event = audit_tree_handle_event,
 998         .freeing_mark = audit_tree_freeing_mark,
 999 };
1000
1001 static int __init audit_tree_init(void)
1002 {
1003         int i;
1004
1005         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
1006         if (IS_ERR(audit_tree_group))
1007                 audit_panic("cannot initialize fsnotify group for rectree watches");
1008
1009         for (i = 0; i < HASH_SIZE; i++)
1010                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
1011
1012         return 0;
1013 }
1014 __initcall(audit_tree_init);